Paul's KR-2S .. my Space Modulator

KR-3

2011-10-08T01:03:00.001-07:00

KR2S Instrument Panel 03

2011-06-22T03:16:00.001-07:00

Just thought I'd throw up the latest work on the instrument panel.

I have added the Dynon AP74 autopilot controller to the right of the 2 circular cutouts and an engraved switch decal. This decal I am very impressed with. I used the same drawing I used for the waterjet cutting of the panel so I knew the holes would line up.

Most of the switches are the standard ON-OFF type including:

Master (battery relay)

Emergency (battery relay)

Bus Tie (relay to tie the two batteries together for emergency start)

Avionics

Gen 1 and 2 (field) (only #1 operational at the moment)

Nav, Landing Instrument and interior lights

The next ones get a little tricky:

the "Primer" is momentary on for an electric prime solenoid

Fuel (pump) #1 and #2 are centre off, Up for main battery and down for emergency battery

The next 4 switches are clustered close to my right hand so I can get to them fast and without much movement of my right hand while flying with my left. During the more dangerous phases of flight I like to rest my right hand on the throttle which makes these switches very handy.

"Trim Isolate" and "AP isolate" switches remove all power from control surfaces.

"Trim" is a momentary switch right beside the throttle. I can operate it while controlling the throttle during landing.

"Flaps" is a momentary down / locking up type switch. I did the non-momentary up so I can dump the flaps if I need to go around (my flaps are split flaps and will be used mainly for drag).

The row of holes above the switched are for LEDs. The one above the avionics switch has the LED inserted.

Some will be Red warning lights like the starter engaged, alternator fail, bus tie, AP and Trim Isolate. Most of the others will be Green for normal operations.

KR-2S Elevator Trim Tab 01

2011-06-06T01:10:00.001-07:00

This installment covers the build of my elevator trim tab.

In this first shot you can see I have already cut the tab out almost to plans. I chose to run the hinge perpendicular to the inner rib to keep the gap fine and ensure no binding. You can see the exit of a cable outer that was already embedded in the elevator. I tried to reuse this but the cable would have had too tight a bend. Have decided to embed a Mac servo in the horizontal tail to maintain a straight run and shallow angle.

This is roughly where I will place the servo. This will be done later when I flip the fuselage over again.

Cut back the foam ready to bond in a false rib.

Here the rib is trial fitted, It is made from an offcut from the instrument panel, Carbon/Ineggra sandwich.

Both ribs in place and the hinge tube is dry fitted. I got 2 brass tubes from the hobby store, one 8mm and one 7mm both with 0.5mm wall thickness. They nest in one another perfectly, a little silicon grease and there will be no play (important to stop flutter).

Here's a closer shot of the inner tube in place.

Here is the whole assembly. The two shorter sections will be bonded in the elevator, the inner tube will be free to rotate.

Here I have made a control horn out of 2 pieces of light angle bonded into a "T".

I have bonded the control horn in a pocket under the skin with epoxy and flox. I have also bonded in the hinge tube.

And this one shows the finished tab. I have filled between the ribs with micro/epoxy and sanded to a smooth radius. This will fit into a similar radius formed in the elevator later. You can also see 2 brass washers to ensure there is no lateral movement to cause binding.

Now to finish the elevator. One side of the opening is on the real rib, the outer side needs a false rib. The plans call for you to just embed the outer rod in the foam and glass over, I think this is much stronger.

To get the 12" inner tube out you need to remove the rudder (if it was already fitted like mine was) and drill a small hole in the opposing rib.

The 2 smaller lengths of outer tube can now be bonded into the elevator ribs ensuring perfect alignment till the flox sets.

The finished tab, works superbly. All I need to do now is to mount the servo and the real control rod.

KR2S Engine Cowl work 08

2011-04-29T03:10:00.000-07:00

First fitting ... I'm really pleased with the lines

Oil access door ended up exactly where I wanted it.

Mmmmmm....

Compare this ...

To how it started. The two spinners are the same article.

KR2S Engine Cowl work 07

2011-04-25T22:49:00.001-07:00

Easter long weekend, great excuse to do a little more work. Last post was the upper deck of the engine cowl, this time I tackle the lower half.

This first shot shows the upper deck repositioned in the mould with double sided tape. The edges were taped to ensure the joggle would release, I will be laying 1.5" over the top deck edge. I found this stretchy duct tape shrank away from the corners so I ended up replacing it with masking tape.

I decided to leave the 3rd mould part off to begin with to make it easier to reach the nose area. This proved to be a good decision and ensured a good layup in this crucial area. Note I have covered with peel-ply to assist with bonding in the next process.

All the materials ready to lay the outer skin ... fine layer of glass to start followed by a single layer of 200gsm CF (45' biased), peel ply, bleeder (vac bag not shown).
Ready to lay up the outer skin.
Outer skin done (sorry, no shots of the vacuum process this time). Note the joggle being formed in place.
Same as last time, marking up for the 3mm foam core-mat. The circle is where I will make a cutout for the carby ram air scoop and will be hardened with CF only (4 layers). The tombstone shape will be a cutout for the nose gear leg.
This foam is quite dense and very rigid but can be moulded slightly by applying heat, as seen here.
Here the foam bonded in with a micro slurry. I did this the same way as last time, weighed down with damp sand over a plastic sheet. Also as before I have left 3" around the edges to harden them in preparation for the fixings. These will have a total of 4 layers of 200gsm when finished.
The end result ... gorgeous ... weighing in at 2.9kg for a total so far of 4.7kg. With a little more trimming to do and the addition of the ram air scoop I'm right on my 5kg target. Note the slight damage demoulding it. Actually there were 2 scares getting it out of the mould, the second was that, with the small round air inlets, it didn't want to let go of the nose mould. Remembered a trick a wise old gent told me and let it soak in water for a few hours ... little more persuasion and out she popped.
This shot shows how well the joggle is formed and those pesky round inlets.
The joggle trimmed up, I will be using a piano hinge along the sides and just one screw each between the inlets and the spinner. This CF sandwich method sure is stiff when finished.

KR2S Engine Cowl work 06

2011-03-13T21:42:00.001-07:00

Yes it's been a long time between posts, life seems to have a habit of getting in the way.
This next series of shots is the start of laying up the actual engine cowl from the mould I made earlier. You will remember I made extensive modifications to a donor cowl because I didn't like the lines, inlets and general fit. I then took a 3 part mould off this plug and am now making the final part(s).

I have decided (based on the advice of another builder) to make the cowl in 3 parts. First the oil access door, then the upper deck with a built in joggle for the oil door and last the lower cowl part, once again with built in joggle for the upper deck. Goal weight 5kg (11 pounds) For a comparison see Mark Langford's @ 3.7lbs http://www.n56ml.com/cowling.html. I think even Mark would agree this is a little too light as it gives when you sand it.

Here you can see the results of vacuum bagging the oil door. I took measurements from the oil filler neck on the engine by extending the line of the neck with a broom handle and measuring where it would meet the surface of the cowl. This became the centre of my door.

Door trimmed to size and then covered with several layers of tape to allow for the thickness of paint later on.

First attempt at vacuum bagging the top deck. I failed to get a proper vacuum on the bag as I slopped a little resin on the tacky-tape in one corner. You have to be impeccably clean when you do this. I could have salvaged it but it would have taken a little more filler and was already resin rich. A good learning experience ... isn't that what it's all about.

One of the other things I didn't like about the first attempt is that I filleted around the door edge with flox which subsequently cracked when I lifted the deck out of the mould. This and the sharp corner at the prop flange would take a little more care next time.

What I did, around the door and the prop flange, is to first lay some rovings tight into the corner. I then built the surrounding material up close to the height of the door with some scrap.

I then laid one complete layer of 45' bi-axial carbon (stitched not woven like cloth)
This time (nervous I guess) I didn't attempt to vacuum it, rather spending the extra time ensuring the right bond and resin ration by hand. Didn't come out as well as you would have expected from Vacuum but still acceptable.

In this shot I have given the peel-ply surface a light sanding and marked it up for the core-mat.

I used 3mm high density foam as my core-mat as it does not soak up resin and remains light. As you can see, very stiff right out of the box. The agent said it could be moulded with a heat gun.

Well he was right, it does mould nicely ...

And holds it's shape once cool.

I bonded the foam in with a light micro slurry and weighted the whole thing down with wet sand. This worked remarkably well.

The final (inner) layer was built up as follows:

- Around the edges 2 strips of 45' CF

- Through the centre 2 strips of CF uni

- Then one more layer of the 45' bi-axial CF over the lot.

This time I successfully vacuum bagged this stage and the result was fantastic

As you can see I have 5 layers of CF around the edges and through the centre and 2 layers with 3mm foam everywhere else. The result is a very stiff assembly that only weighs 1.8kg (under 4lb). I'm happy with that.

Oh and the door looks real flash too.

KR2S O-200 Second Engine Run

2011-03-13T21:30:00.000-07:00

No more sitting in the plane pretending and making vroooom noises.

I have real vroom noises.

KR2S VHF COM Antenna

2011-03-13T20:44:00.000-07:00

Radio antennas in wood or composite aircraft can be easily installed internally as follows
Here I am cutting copper tape from a kit from RST in the states. I think I have enough for a hundred more tries. I will have one element up the vertical tail fin and the down element bonded to a stick of balsa and mounted in the tail structure,

This is the upper element in place. I will later cover it with a thin strip of FG tape.

Ferrite toroids in place following Jim Weir's instructions. Apparently the first blocks 90% of reflected power, the second 90% of the remainder and the third 90% again. Theoretically 99.9% blocking ... close enough for KR work =)

This shot shows both elements in place.

Cable end preparation tidied up. I put another layer of heat-shrink over the toroids after this shot was taken.

All done.

KR2S Prop Clearance

2011-03-13T19:34:00.001-07:00

Here is my Propeller clearance check ... this shot with the NLG tyre deflated and showing a healthy 7" clearance.

FAR Part23 section 23.925 states that “There must be a clearance of at least seven inches (for each airplane with nose wheel landing gear) … between each propeller and the ground with landing gear statically deflected and in the level takeoff, or taxiing attitude, whichever is most critical.” I have 9.5" so I think I'm sweet.

FAR 23 goes on to say “In addition, there must be positive clearance between the propeller and the ground when in the level takeoff attitude with the critical [tire(s)] completely deflated and the corresponding landing gear strut bottomed.” Positive clearance ... I still have 7" with the NLG tyre completely deflated so I'm sure this passes.

KR2S Forward Deck

2010-07-30T01:32:00.001-07:00

Welcome to the segment where the forward Deck is first built then heavily modified.

The first few are from the original builder, this one shaping the foam between a temporary template and the firewall.

And this one from the builder showing the building of a fuel tank. This work had already been stripped out when I took over the project.

I have a couple of concerns with the KR2 design; 1. there is little or no baggage room, and 2. they tend to be a bit tail heavy (mine probably more so with the larger tail and the extra stretch). I needed some way of addressing both of these so I came up with a forward locker concept. With this and a small space behind the seats I could move luggage around to balance out the plane while loading it. The W&B should remain relatively stable in flight as the fuel is in the wings.

This one then is me mocking up the space I can use. I settled on allowing 200mm behind the instrument panel as this was more than enough for my plan to fit a Dynon D180 and Microair radios. This would bite me later on (see the second instrument panel post).

I made a simple male mould out of ply (sorry no photos) and then covered this with a couple of layers of glass to make the outside skin of the locker box.

And this is what it looked like once removed from the mould. In the foreground you can see the start of the centre wall.

Yours truly preparing a piece of foam ready to attach to the inside of one of the walls. Later I will fillet the edges and then line the inside with a layer of glass.

Here is the locker finished and sitting in place ready to be bonded under the FWD deck lid. Note the inspirational poster on the wall =).

Still not attached but checking the fit into the aircraft.

Here I am working out how large I need to make the hatch. My original thought was a pair but eventually settled for just the one. Also note the step built into the deck to line up with a beautifully created canopy frame thanks to the original builder.

This is just before I bonded it, the forward cutout I added to improve access to a tiny bit more space in front of the locker and a small piano hinge in front of the midpoint locker bulkhead. This pin will lock down the front edge of the deck, the sides will also be pinned as you can see.

Deck pinned in and locker ready to flox into place. As mentioned earlier the deck is held by piano hinges forward and sides and the aft edge is attached to the instrument panel with a few screws. This baby is not coming off in flight but will be easily removed on the ground to help with access for maintenance

All bonded in and the door cut out. I should be able to fit a small hiking tent and a sleeping bag in there.

KR2S Instrument Panel 02

2010-07-28T03:24:00.001-07:00

It's been a while since my last post ... been buying a 12 acre property for our future retirement and setting it up for tenants.

In an earlier post on my instrument panel it finished off looking like this, a mock up of the instrument panel. I had decided to mould it out of carbon fibre firstly because it looks good and secondly because I wanted to curve and roll the lower edge under.

Here I've glued a stack of MDF to create a mould for the lower edge of the panel. Hardest thing is to remember to work in reverse. As they say ... think it through 30 times, measure 20 times and cut once (hopefully only once).

Painting and sanding to a smooth finish.

This is my stack under vacuum. 1st a nice looking twill CF then a second CF this time biaxial then 4 layers of Inegera (new fibre like Kevlar but cheaper and easier to use). This then followed up with 2 more layers of the biaxial. I had a seal problem that took a while to sort out so the result wasn't as perfect as I wanted but it will do. {Learning all the time} (the CF on top of the stack is a dodgy old piece I was using to help absorb excess resin)

Out of the mould and trimmed slightly. Doesn't look half bad =).

More trimming and fitted in the aircraft. Looking better all the time. Can't wait to have all the hardware in it.

Next is a drawing in Autosketch (baby brother to Autocad) most of these lines were sent to a waterjet contractor to do the cutting for me.

This is a trial run of the watrejet. had to make a few adjustments but pleased with the accuracy of the result.

Final cut and populated with hardware. Ain't she pretty?

and one installed in the plane.

Here I an filling a few pinholes with a mixture of epoxy and carbon black. I will paint the panel later with urethane.

Bonding the D180 mount with epoxy/flox. It doesn't need to be overly strong as the instrument will pull it into the panel. I didn't want rivets or screws showing.

These warning lights are dual colored LEDs. They will be soft green when the switch is on and the fuse is OK but will glare bright red if the fuse blows.

One of my pet gripes about panels with steam gauges in smaller aircraft is there is no room for a glovebox to chuck the ERSA, a chocolate bar and a drink into. So I went for a glass panel and built myself a glovebox.

A close look at the glovebox.

As you can see I left plenty of space between the instruments and the locker for cabling and connectors ... or so I thought.

As you can see instead of the Microair transponder I planned for (180mm deep installed) I ended up sourcing a Becker at a good price. The Becker is 240mm installed and I had allowed only 200mm behind the panel.

The offending Becker transponder installed, nice pair!

Well something had to give, and I wasn't about to go backwards and install a Microair transponder. Some slight modifications to the locker were in order. Mark up a relief ...

and cut along the dotted line. Oh how I hate cutting already finished =(

Reverse the piece just cut out and I almost have it sorted.

Next I need to flox some captive nuts into the edge of the forward deck so I can fasten the instrument panel to it. I twisted the wings up on these panel nuts for better resistance to twisting and loosened the crimped in threads a bit. Stood off to the correct depth with brass tubing left over from the pitot tube. This tube will remain bonded in place and act as a guide for the screw. Tape is so the flox won't bond to the panel and you can just see I have painted release agent on the tip of the screw so no epoxy can get down the threads. Worked a treat.

I carved pockets in the forward deck, filled them with flox and then strapped the panel in place. Whan the flox went off I removed the screws and let the whole thing harden.

The result looks great, I went to great lengths to get black 6-32 hex head screws and with the orange fibre washers under then I think they look a treat.

Couldn't resist loading up the panel to see what it looks like. I am very pleased with the result. The space to the right of the radios is for my GPS.

KR2S Engine Cowl work 05

2010-04-03T21:22:00.000-07:00

Well it's been a lot of work but I finally pulled the mould off the plug I made. This is where I left off last time, the plug almost finished in primer.

Next I added a few coats of gloss to act as the base for waxing. This really shows the imperfections. I wet sanded this down to about 400 grit then polished with auto cutting compound then several coats of mould release.

Here I am setting up the flanges for the top 1/3 of my 3 part mould. I'm making it 3 part for ease of handling but the final cowl will be only 2 parts. As suggested by a fellow KR builder I will build the oil door first in the middle of the top 1/3 of the mould. Once set I'll trim it to size then hot glue back into the mould. Attach the nose 1/3 to the top 1/3 then I'll then build the upper cowl with a joggle over the oil door. Once again I'll remove the top cowl and trim it to size then return it to the mould, now adding the final 1/3 and then lay up the lower cowl with a joggle over the edge of the top cowl. A lot of up front work but it will save time down the road.

Notice I have used builders plastic to protect the forward deck, this will bite me later.

Here I have added non hardening hobby clay to the gaps in my formwork and trimmed it to form a perfect edge to the plug. The white dots are domed plastic hemispheres that have nails in them. They are used in the legs of furniture to protect them and make ideal locator sockets in the first mould flange. Once removed a corresponding dome is formed in the mating surface of the second mould flange when it is laid up.

Tooling gel-coat added, this one was spray on.

After the gel set up I filleted the acute angles with micro then 3 layers of CSM. Notice the polyester has wrinkled the builders plastic. lucky this is only in the flange area added for bagging and will not affect the final part.

Here I have added formwork for the lower flange. Again I have used the domed plastic hemispheres to make locators in the mould half.

I did not take any photos of laying up the lower 1/3 but trust me it was a real b!tc#. Wet layup upside down is no fun at all, resin drips everywhere, gets on your skin and runs down your wrists. I had those plasticated overalls on and the resin still soaked through them and burned my back. I found a neat 3" mini paint roller that was fantastic for wetting out the glass. The hairy ones are only a couple of bucks each and will wash out in acetone without falling apart.

First 1/3 removed, cleaned and trimmed. Notice the neat indents from those dome things.

Top and bottom thirds all finished.

The nose 1/3 was a simple layup but because of it's complex curved it was difficult to remove it from the plug. So much so that I had to partially destroy the plug to get them apart (hope the moulds are good ... no going back).

All 3 parts keyed together with neat little domes and corresponding sockets.

Now all I gotta do is pull the final cowl, yeah?????

KR2S Engine Cowl work 04

2009-11-17T02:19:00.000-08:00

Back on the cowl again. If you have been following this blog this is where I left off last time. I was given a basic O-200 cowl and took to it with a saw as I thought it was draggy and ugly (and it didn't fit my mount length either). I'd narrowed the inlets from over 5" to 3" and tapered the spinner face from 13" to 10". All in all it was starting to take on a shape I was pleased with. BUT ... I am far from taking a mould off it yet.

Here I am checking the symmetry of the sides just behind the inlets. Made a template out of MDF then flipped it over to check the other side.

Close but just a little off. I made indicator blocks out of MDF ...

Then glued them in place to show me where to fill.

Started filling (I'm going to soon get sick of that word ... filling)

Some time has passed and I have the new profile on the underside of the belly (other post).

This is the first time I have offered the modified cowl up to the fuse. I have been relying on a template on an engine stand. The shape of the cowl bottom does not quite line up with the belly so some more adjusting is needed.

Experimenting with potters clay. This produced a remarkably good profile quickly but had the disadvantage of drying out. Later on I found I had to cut this out in strips and back fill with a polyester filler.

Resulting profile taking shape.

And the finished clay model. Note the plastic to keep it moist.

I've now finished with the belly mods and have flipped the KR back onto her wheels ... well the 2 mains anyway. I left the nose leg off so I could finish the cowl plug without it getting in the way. Trial fit the prop to check the ground clearance. I have 3.5" here but she is sitting in a nose down attitude. Hope to get 6 to 7" clearance when finished (even if it means trimming the tips again).

Another view of the plug taking shape.

Strapped an RV-6 Ram air inlet to see how it looks. later I will fit this but will be tapering the training edge flush with the belly.

Some final shaping of the bottom of the cowl. Even with the 2.5" lower belly the oil tank on the O-200 protrudes a little. Eventually this will be covered by the ram air scoop but I still need a reasonably good shape to pull the mould off. You never know, somebody else may want a cowl out of the mould and choose not to add the Ram air.

Sanding and filling and sanding and filling and sanding and filling and sanding and filling and sanding and filling. Gawd it makes an awful mess. See how the dust is picked up in the flash.

WOW! now I'm getting closer. Put a coat of fast dry primer on it so I can see all the flaws invisible when you have the mottled appearance of many layers of fill and old paint.

Certainly starting to look the business, still some minor fill jobs to make it perfect.

And just to remind you why I am doing all of this, here is what I started with.

KR2S Instrument Panel 01

2009-09-13T01:39:00.000-07:00

Here is my journey to work out the instrument panel layout. KR-2 has limited panel space so the options are to fill the entire panel with conventional "steam" gauges or go electronic and get a MFD. I chose the second because I wanted a neater setup and some well needed storage space.

This is some early work the previous owner did on the panel.

As you can imagine, slip a transponder, some switches, circuit breakers and lights and there isn't space for much else. Adding weight to my decision was that only a couple of the gauges you see here came with the panel. Time to modernise.

This is the first attempt at an instrument panel. Grabbed some cheap ply and started cutting. Whatever didn't look much like instrument panel went in the scrap bin.

First attempt is a little squeezy.

Second attempt a little better after chopping the sides out a bit.

A friend challenged me to think asymmetric. I'm 5'8" but If i were to take a taller passenger they would need more knee room. So after a little more trimming the final shape is this.

Starting to lay out components leaving sufficient room for a generous Glove box/map locker.

Components from Top L to Btm R are:

ASX-2 combined ASI/Alt as a backup.

Daynon D-180 EFIS and Engine monitor

Master Warning Lamp

Flightcom LSA (2 place) intercom

Microair 760 Com

Transponder (TBD)

GPS moving map (initially a PDA running OziExplorer later a 7" LCD running off a laptop)

Glovebox with power and computer connections inside

Air vent

Start Master/Start switch

13 toggle switches with polyfuse protection and dual color LEDs to show normal or fail modes

Carby Heat

Throttle

Mixture

(passenger side has an air vent, 12v outlet and an audio input jack wired to the intercom.

Here it is with real or simulated components in it. Ill play around with the placement a little before I cut the real thing. Actually went with the 2.25" ASX-1 as the digits are only 1mm shorter than the ASX-2.

And a little more mockup work

Suggestions anybody???

KR2S Spinner #2 part 1

2009-09-13T00:07:00.000-07:00

Some time ago I had a go at shaping a spinner plug by stacking polyurethane foam on a base and shaping it on my lathe. Although this was somewhat successful (and an excellent training exercise) I wasn't happy to use this as a flyable component. The problem was with different material density/hardness of the foam to glue, creating slight bumps near all the glue lines. This first unit served me well as a dummy spinner to help shape the cowl but now it is time to build the real one.

Call in another favour from my mate Gordon who has a flash lathe (mine is a lightweight toy). I got Gordon to build me a similar plug to the first this time out of MDF. The shape and finish of this one was almost perfect, good enough for a non commercial build.

What you see below is the plug with a couple of coats of clear polyurethane varnish. Once this hardened I sanded the fur of and applied several additional coats, sanding between each.

Several coats of varnish later she is looking great. the tip was a bit off so I slapped a little epoxy/micro on it and sanded to shape.

Waxed several times and painted with release agent it is ready to attack with gel-coat and polyester.

Eeeek green goo. I thought tooling gel was orange. Oh well as long as it works. Big flange to allow me to vacuum bag the spinner later on. I received mixed advice about whether to make this a split mould or not. As you can see I went with the "not" option as there were no negative curves to stop the cast part from coming out. Later I will tell you how this was almost a failure for me.

Let the gel-coat set up till just tacky then start laying up the first layer of glass to stabilize the gel. I'm using CSM and polyester resin for this. Cheap and easy to use.

Once the entire surface has been covered take to it with a roller to work out any trapped air and to incorporate the resin and glass matrix.

Let the first layer set, knock the surface down with rough abrasive and then add several layers more. This is the finished mould.

Add strips of ply to stop it from rolling around when laying in the final part. I set these in a bed of flox and polyester.

Add a few scraps of glass to ensure nothing moves and let it set.

Now this is where the decision not to do a split mould came back to bite me. You see I had built an extremely strong mould (as you should) and the MDF plug was equally robust. There was going to be no way on earth either was going to move even the slightest amount so I could work them apart. After much huffing and puffing and head scratching I decided the only way out was to cut my lovely plug out of the mould. Carefully hacking at the soft MDF it only took a few hours to remove all the plug and the result looks like this. Yes that is a scratch ... damn it. It'll polish out.

KR2S (re)Drilling the Prop

2009-08-21T02:48:00.001-07:00

Just a short post to show you how I got precise alignment when re-drilling my propeller. You see I got a second hand 72"*66" Bishton prop for a good price but it was off a Lyc O-320. Same centre hub but different bolt PCD and of course too long. Had a local prop builder cut it down from 66" to 60" and fill the original holes and drill them to suit the O-200. Some how this ended up being a fraction off and the bolts would not cleanly line up with the flange.

This photo shows the prop sitting cleanly on the Saber extension I have. Two of the bolts were a clean, drop in fit, two would go with a "little" persuasion and the last two not at all.

Solution ... refill the holes and re-drill them. I came up with a highly precise alignment tool. The 6" Saber extension is CNC machined so it couldn't be off at all. I filled the holes part way up leaving the dowel holes as these ends were already correct.

I had a friend run a 1/4" drill through the centre of two AN6 bolts on a lathe and then inserted these in either end of the extension. Now when I passed this extra-long 1/4" drill through these guides it was held at two points about 6" apart and precisely aligned. When finished 5 bolts dropped straight home and the last went home with a slight push. Happy with this result.

KR2S Flaps 03

2009-08-21T01:19:00.000-07:00

When we left the last post I had finished shaping the flap, it has a very strong spar and now has the hinge spar attached.

Next it is time to encapsulate the hinge spar and harden the outer surface. Here I am tracing the outline of the pieces of glass I need onto a piece of builders plastic.

Here is the underside all glassed over. Note the rib extensions I had on there earlier to ensure I replicated the original placement have been cut away. The hinge now serves this purpose.

Here is the top surface (will be facing down when fitted). You can see a little 3m sanding guide coat (the black areas) to help ensure a perfectly flat surface.

This shot shows the relief I added to ensure the flap did not interfere with the aileron cable.

I have marked two lines to indicate the flap extension limits. The one on the right aligns with the flap surface when deflected to 60degrees, the left one where the top of the new fillet will be. What I am trying to do here is mock up the end of the fillet so that it can slide in behind the fillet on the wing as it deploys.

Here is the fillet partially formed. I will attach it before finishing the shape.

This is where I formed the back surface to support the fillet up against the fuse side. There are a number of layers of packing tape against the fuse to ensure adequate clearance.

2 things in this shot. 1st the back surface of the fillet is facing down, will back this up with a little flox later. 2nd I have marked out where I will cut the spar and lower surface back to to attach the rod end.

Nicely prepared and ready for the rod attachment bolt that will be floxed into the centre of the spar.

This is the rod end I will be using. It will be embedded 2.25" into the spar and floxed in place. Plenty strong enough.

This block was to align the pivot bolt parallel to the spar centre line. It is covered with packing tape to ensure I can get it off when the epoxy sets.

The final result ... a thing of beauty. Believe me you could lift a truck on this (well almost).

This next one is a mock up of the actuating arrangement. It will be embedded within the trailing edge fillet once finished. The pivot is 1/2 way along the 11" flap, ie. 5.5" from the hinge. To raise the flap 60 degrees i will need to lift the pivot about 5.5". To retain reasonable alignment on the arm without going over centre at either end of this travel I need at least 7" of arm. If I faced the arm the other way I will be on top of the aft spar of the wing, this way I am in a clear area in the first bay behind this spar. Later I will fabricate a torque tube from this side to the other and actuate it with a 12v linear actuator something like the like the Jabiru. http://www.sky-craft.co.uk/pdfs/21aFitElectricFlaps.pdf

Here it is in the extended position. (in the background the 3m guide coat powder)

Fillet foam and front glass attached.

In place this time. With a little filling and sanding it will look as if it all belongs. I'm pleased with the result. Now all I have to do is build another just like it.

KR2S Flaps 02

2009-07-21T02:42:00.000-07:00

Since last post I have filled in the last couple of panels into the flap skeleton. You can see where I had to thin the outer panel to clear the bell-crank (which it does by a millimeter or 2) The recess for the hinge spar is also cut.

Here I am preparing the hinge and spar with captive nuts. The nuts are bonded onto the spar and a small pin driven into the spar ensures they do not rotate.

In this one I have cut reliefs for the captive nuts. I protected the back of the nuts with a little sealer to stop the flox from getting inside. I will be cutting away most of the triangular portion of the ribs to lighten them up. they were there to ensure the flap was mounted accurately.

Hinge mounted to wing with packing to allow for the final thickness of glass. I am going to apply 2 layers of bid over the flap surface and wrap it around the hinge spar to ensure a strong mounting for the hinge.

The hinge spar floxed into place.

Ah ... success. Once set and cleaned up the flap was an almost perfect fit. Here it is set up to simulate the maximum deflection of 60 degrees.

Another view of that 60' down.

More soon.

KR2S Flaps 01

2009-07-11T03:09:00.000-07:00

Well this is a little unnerving, modifying work that had already been completed.
The previous builder decided to build the stub wings without flaps (KISS), but by all accounts the KR2 is a slippery little rocket and can benefit from additional drag in the landing profile to shorten up the landing roll and to help with visibility over the nose. I have decided the simplest and probably the most drag producing solution is a split flap arrangement. Hinged off the aft spar there is sufficient room for 2 * 600mm by 285mm (23" * 11") flaps giving a total of 3.5 sq feet of flap. Hopefully if I dangle them enough this should be enough. I've seen a report that split flaps are affective up to 60 to 70 degrees down, I'm going to go for 50 to 60. They will be actuated via a torque tube acting on the inboard end much like another builder here in Australia Darren Crompton. I'm thinking also of an electric actuator to simplify mechanical linkages.
This first photo has me cutting out the existing lower skin. As you can see I have left the hardened trailing edge in place to support the upper surface.

Here it is with the lid off. To get my flap as big as possible I will extend it all the way from the wing joint to the fuselage skin. You can see the original builder has put a PVC guide for the aileron cable near the root but if you look closely it is actually in contact with the cable. As I will need a space between this and the new flap skin I will have to displace this guide, fixing this small problem along the way.

Another shot of that guide, note the lightning hole that the cable was meant to go through, I will make a little filler to allow me to mount the guide lower.

Here I have hardened the inner skin just to protect it a little and to firm up the upper surface.

This is how I sandwiched a 10mm sheet of foam on both sides with a single layer of BID. I will use this in many places but for the flaps I will be using it for ribs and the centre spar.

Two spars cut from the foam sandwich. For now they are the full height of the aft wing spar but later I will trim them down to the height of the hinge. I have done it this way so I can get an exact profile of the original ribs before cutting them down a little.

This is a picture to remind me of where I have positioned the flap spar 5" out from the hinge gives me an almost 50/50 split fore and aft of where I will be applying the force to actuate the flap. My calculations show that I should be able to get almost 60 deg. drop by moving this point down 5" to 6". I should be able to hide the torque arm inside the wing fillet @ 6" travel.

Trial fit of the flap spar.

Spar and ribs trial fitted into place. Scrap foam has been set up to support a 10mm sheet of foam for the flap surface. (I later changed this to 27mm, the same as the hinge and the spar to simplify glassing it later.)

Hinge in place. You can see here I have dropped that PVC cable guide.

Here is the spar and the ribs bonded together. To strengthen all the edges and joints I removed about 5mm of foam and filled it with flox. Very strong and only 155 grams at this stage.

Here the centre section has been filled with foam. You may see the subtle curve which is the same as the original profile of the wing in that area.

Dry fit the hinge spar in place. It is made of 6mm (1/4") Hoop Pine marine 5 ply. I'll use the same materials on the Ailerons when I cut them out.

Cutting back the wing ribs so I can run the flap across the top of them. Amazingly there is still plenty of support for the upper skin and trailing edge.

A shot of the outer end cut down also. I will have to thin the flap around the aileron bell-crank mount but it should fit OK.

Here I'm starting to fill in the outer portions of the flap.

That is it for now, don't forget to send any comments you nay have. I always appreciate feedback.

KR2S Exhaust Augmentors 02

2009-07-11T02:01:00.000-07:00

I apologise for the long time between posts, been busy.

When I left off last time I had built the two channels for the augmentors and lined them with fibrefrax.

Next I covered the fubrefrax with 2 layers of BID using high temp vinyl ester resin. This stuff stinks like crazy, need plenty of ventilation.
A little post cure to harden things up.

Now it's time to make sills to attach the cap to. I reused the chunk of foam I cut out of this slot and dropped the top surface a little to allow for the thickness of the cap and rounded the edges for a generous fillet. Packing tape allows easy release and ensures a smooth finish when I cut the foam out later.

FAILURE number ??? (too many to remember them all). You see I have been working almost exclusively with Epoxies but for this fillet I was using VE. I mixed VE with flox to make the 900mm long ledges but as they started to harden they started to shrink. Over the 900mm length a 2.5% shrink amounts to a shortening of the top edges by 25 to 30mm. This was enough to start bending the existing channel up out of it's bedding. The cracking noises as energy was pulling the edges away was quite alarming. S#!+ what do I do now....? I pulled out a grinder and cut out the semi-hard resin, I'll have to come up with a recovery plan. Had I known about this earlier I would have done 2" segments 2" apart, let them set then come back and do the other set of 2" segments. Oh well experimental category is for education.

Well I mixed up a batch of resin and bonded the channel back into place. Changed the plans to have the cap extend past and over the channel edges rather than inside it. This is a sheet of BID & VE I made up on a piece of glass. Nice and flat.

This is a shot up the augmentor with the cap bonded into place. I will come back later and fillet the joints once the aircraft is back on it's wheels.

This shows the transition from augmentor to the exit ramps.

Here I'm trying out my vacuum bagging rig. I'm making a wide sheet of Glass and will later cut it into strips and stack them together to make a sturdy strip to harden the front edge of the augmentors and for a place to attach piano hinge for the cowl.

Strips bonded together.

and bonded to the front lip. You wouldn't believe how tough this is now.

I've fared back from the lip and have started to attach the hinge. I will cover the whole lot later with a final couple of layers of glass to protect it from stone damage.

2 layers if glass and peelply

Trimmed, sanded and a couple of layers of epoxy primer. I will come back much later and do a little bit of filling and sanding but for now I just want to flip her back the right way up so I can start the final push for the finish line.

KR2S Exhaust Augmentors 01

2009-04-12T19:56:00.000-07:00

Long time between posts, got distracted with other priorities. Back now.

Time for an update. At the end of the last post I had the top and sides of the cowl 80% complete but couldn't finish the bottom because I couldn't match the cowl up to the belly. The reason for this was I was going to extend the belly down ~60mm to incorporate augmentors and to better cater for the O-200 oil tank.

But first I needed to flip her over. I chose the rollover "D" as I was already on wheels and it seemed safer.

Flip over was easy with a few extra hands for safety. Roll her onto the drive, check for power lines then over she goes. You can just see a pair of trolley wheels to help roll it back into the garage.

This shot of the belly profile I want.

And this is what I achieved. But I've stepped forward to show this. Back to building it.

First I Extended the firewall bottom edge by the 60mm I needed. Note the fillet I built up to strengthen the corner (flox in this case).

Next I laid out 3 sheets of 20mm polyester foam to meet the profile I wanted. This technique is based on work Mark Langford had done before, modified slightly based on his learnings and other web research. I did away with NACA type walls as they added little in reverse. I will also close in the first 36" to make 2 true augmentor ducts 6.3" * 2.4" * 36" long. This gives me a 1:1 inlet to outlet area, more than enough. I've seen an RV4 with 2.7" in and 78% out with no cooling problems.

Here they are glued in and trimmed to size.

Next shape the ramp from new belly to aft fuselage.

1/2 hour of sanding and nearly done. Love converting foam into dust.

Shaping finished, side edges rounded, front edge cut back and hardened with a fillet of flox. This will help attach the layer of glass to come.

Laying out the cut lines for the augmentors. Don't need to bond the glass between the lines as I will be removing this foam.

One layer of glass to protect the foam.

then cut away the foam inside the augmentors. To help the removal of this foam I did not glue under this area.

The partially finished channels.

Here I have hardened the edges with flox for when I glass the inside of the duct. You can just see a fillet on the bottom corners, I decided these were not generous enough so later added to it with micro filler.

For the ducts I will be working with high temp VE. I needed an accurate means of measuring below the 1g my scales were capable of. came up with this balance lever which now gives me 1/4g accuracy.

1st step in finishing the augmentor ducts was to insulate with Fibrefrax. I carried this up the sides a way to add to the level of protection.
More soon.

KR2S Engine Cowl work 03

2009-02-02T02:29:00.000-08:00

When I finished the last post I had two new inlets made and trial fitted them.
This edition sees me attaching the inlets and filling and sanding and filling and sanding and ... you get the idea.

This photo is of the jig I made to ensure the inlets were parallel to the prop flange which is parallel to the firewall. It also aligns them equidistant from the centre line and aligned vertically. Don't worry about it looking off in this photo, I hadn't done the final align yet.

Perfect opportunity to practice mixing flox. If you haven't done it before this is roughly the consistency you are looking for.

A little flox applied to the inlets to bond them in place. Note the size of the original inlet, 5" each. Enough to cool a big six not my small 4.

Bond completed, just let it go off then we can start filling.

The first of many applications of filler. This one is epoxy and micro, I found it to be the easiest by far to work. It doesn't go off too quick (especially in our Aussie heat) and it doesn't set to a concrete-like consistency. I tried other fillers, poly resins and even auto body filler and came back ti the micro. In later photos you may see the different colours as I experimented. That's why they call these things 'Experimentals'.

First layer roughly smoothed back. This is really starting to take on a pleasing shape. After a while you learn to 'read' the contours of the filler with your hands. Sometimes closing my eyes helps to concentrate and feel the subtle changes in profile. matching one side to the other will be a challenge.

This is the method I employed to check the curve from firewall to spinner. I will reattach the plug to the airframe soon to finish the final shaping.

Mock spinner, she's really looking good. If it's pleasing to the eye and pleasing under the hands it must be efficient in the air ... and fast I hope.

Curves from the other side.

Can you recall what I started with??? More soon.

KR2S Engine Cowl work 02

2008-12-27T23:22:00.000-08:00

Just to recap where I got to in the last post, I had extended the cowl at the rear and necked down the spinner flange from 13" to 10" diameter. I was still left with an ugly gap between spinner and flange. (don't worry this spinner is a mock up. I will either make or buy a better one later)

Here is the infill I made, the next few photos show how I did it.

Cut a few pieces of MDF roughly to size.

Stick them in the lathe.

Work them till the shape is what you want.

Cut the centre out with a fly-cutter to suit the prop hub.

The end result, a neat fit and it helps to hold the cowl firm from the front while I attach the chin parts permanently.

Looking good I must say. The photo above is a stack of 3 x 12mm MDF. in the photo below you can see I have added 2 additional disks to locate the stack forward and aft, exactly lining up with the front face of the hub. When the plug is finished the first stack will form part of the plug sitting 12 mm aft of the front face of the hub. I hope this will be enough clearance for the prop and spinner.

Next I wanted to work on the underside of the lower cowl. If you remember I have dropped the firewall 2.5" below the belly to allow for augmented outlets. The original cowl came with an outlet that protruded below this so more surgery was required. Previously I had made a template to bend my SS firewall ears around. Mounted to an engine stand it now makes a handy mount for working on the plug.

First job, glass a strap to stabilise the chin area of the lower cowl.

Next I marked where I needed to cut the original exit ramp. As you can see even with my 2.5" lower edge it would have protruded well below the lower edge.

Apply some temporary straps and then cut it off. I love composites, you can cut stuff away that you don't want and add things that you do.

I'm going to fill this area with foam so I built a flat sheet of glass to support it. Also in this photo you can see I have attached the lower flange to the cowl with tape straps. I will later add some more on the inside to make sure it doesn't move.

2 cans of gap filler later... I used aerosol rather than hand mixes as it is more controllable and less cleaning up. WARNING here. this stuff is air cured and goes off by drawing in humidity. If you put too thick a layer it will take a while to go off. Not a biggie, I cut through exposing a soft spot, let it cure for another 1/2 day ind it was fine. I ran out of foam, will be filling in the rest when I can get back to the shops.

A shot from the back showing how it expands. I laid it level with the wood and is slowly rose as it set.

Grab a saw and start carving.

Amazing how quickly it starts to take shape.

Here is a side profile part way through.

I will leave the belly for a while till I can get more foam.

Next job is making up a template so a friend can turn some plugs to reduce the air inlets from 5" to 3". I cut a sheet of MDF to fit the current shape and then drew on what I thought the final shape might look like. This one obviously too sharp.
3 options for the final shape.
- Just the original rounded to the 3" size,
- Mid-length, small amount of filling required.
- Longest gets the opening close to the prop but I think it will look ugly.
Comments here, I think the mid size looks the best, what do you think?
Here is a longer view.

A friend (thanks for the fantastic job Gordon) turned plugs for me based on the template I drew earlier. First a reminder of the openings as they were.
Here with the plugs inserted. I still have to line them up properly, bond them into position and then the shaping can get serious.

KR2S Engine Cowl work 01

2008-12-06T22:13:00.000-08:00

What follows is the development of the Engine Cowl.

You may have noticed in earlier posts that when I bought the aircraft it already had some work done on a scrathbuilt engine cowl plug. Here are a couple of shots of this early work.

Although this was a great start I wanted to change a few things
Several things hapened early on,
1. I wanted to make changes to this design to lower the firewall bottom edge to line up with an augmentor system based on Mark Langford's work
2. the air inlet had to be made more aerodynamic so the C150 box had to go
3. I got given an old cowl off a KR-2/O-200 to work with.

So off came the early work, the C150 air box went back to it's owner and I started sizing up the O-200 cowl.

After many measurements it became obvious this cowl was meant to be used with a 3" prop extension. If I lined the spinner face up with the prop flange the cowl wouldn't fit over the rocker covers.

If I pulled it forward to clear the covers the prop flange was inside by 3". Also the spinner flange was nearly 13" diameter and looket all out of proportion on a KR2. In an earlier post I built a spinner mockup (as practice) based on a C152 shape and 10" diameter (same as Langford's)

Next the inlets were over 5" diameter each, enough air to cool a high power 6 not a 100hp 4 cylinder. Target for this (considering I'm doing augmentation and plenums) is 3" as shown.

I found inlet bellmouths that were made for turbochargers on drag cars. These were 3" and made from spun aluminium. Later I may bond them in but for now they give a good idea of the final size. Also I have a 10" spinner blank in place as a reference to future cutting and shunting. Also note the ram air inlet, I think it is ugly so it too has to go. Yes I will be keeping some of this cowl.

So here is the starting point, the mock spinner is in the right location on it's mock 6" extension. The cowl is in the right location, pulled forward enough to clear the rocker covers by 1/2". I now have a 3" gap at the back and 3" to work with at the front.

But that spinner flange is way too big. A piece of electrical conduit is used as a guide to check the curve I would like to end up with. If you look at the earlier photo is doesn't curve and doesn't look at all aerodynamic.

Another shot of that step.

First of all I need to fill in that aft 3" gap. I started by using the old cowl as a plug and laid up a cpuple of layers of CSM.

After that was cured I made a cut 1" in frm the aft edge and inserted the piece I just made. This shot is the popcicle sticks hot glued into place to make a frame to hold the new piece while I glass it.

Here you can see the insert in place.

Extended top cowl in place now supports the lower cowl. It is quite obvious from this one how much I had to move the cowl forward.

I had a friend cut me some MDF disks in 1/4 inch sizes from 10" to 11" to use to stabilise the spinner flange as a neck it down.

Here is the layout for the cuts I intend to make to neck the flange down from ~13" to ~10".

A Sabre 6" extension is now in place and is the reference for this work.

Starting on the top cowl I made my cuts. I wanted to start the curve down to the spinner quite a way aft so the centre cuts were quite long.

Here I have clecoed the flange into it's new location. There is quite a lot of spring in the glass as the builder of this cowl built it too strong (and heavy hence the reason it is not on a flying KR-2)

Side view of the new profile. Starting to look good already. Roll back to the start to remind yourself of what it started like. As you can see the bottom cowl is still to be done.

Glass on the inside to hold the fingers in place.

Layout on the lower cowl.

Lower cowl cut and clecoed into place.

After cutting the spinner flange away and also loosing that ugly ram air inlet the remaining piece I left to hold the cowl together is obviously not going to fit into the new profile. It will have to go as well, but before I cut it away I will have to add another brace.

Here I have added another internal brace and cut the old one out.

Now it's really starting to look sleek.

Here's a flashback to remind you where I started ... ...

More soon ... ...

KR2S Fuel Tanks

2008-07-02T04:09:00.001-07:00

This set of photos were taken while the wing tanks were being build by the previous owner. Once again a great job.

This first photo shows the left wing inverted with the raw foam on the upper wing surface and some of the foam ribs.

Here is another angle of the early foam work. You can see tubes used to join the two cells together. The lower on in this photo is actually the upper one once the wing is upright. It allows air to move freely. Later the lower ones were replaced with simple cutouts. In this shot the ribs are still the full height of the spars. they will need to be lowered to allow room for the foam and glass lower skin.

This shows the rib dropped to the correct depth, those tubes are now in the way and will be removed. You can see a ledge has been built to support the lower skin along the spar.

I think this one shows the foam glassed over. Note the tubes have been removed and passages allow fuel to move between bays at any angle of attack.

This is a shot looking outboard at the filler opening.

Another shot of the filler neck. Just in front of that is a pale looking spot. This is actually a small depression in the roof of the tank. After the tank is sealed a small vent tube will be inserted through the lower wing skin and sit up into this depression to act as the vent.

Fuel pickup in place. The first hole @ 51/4" is an earlier trial fit that didn't work too well.

This shot is looking inboard and aft in the wing tank after it had been placed upright You can see it has been fully sealed inside to prevent any chance of a leak. The pickup is temporarily plugged.

This shot shows access holes in the upper surface used to seal the tank. One of them will be used for a mechanical gauge, the other 2 sealed off.

This is the fuel gauge components. Simple and effective. I should be able to just look out over the wing and confirm what is on board. I intend to run an electronic fuel flow totaliser but it's always good to be able to physically see what you have on board. I believe with the 2 bays in both wings it should top out at about 140 litres (38gal).

Here is the gauge in position. I will fill around it when I finish the wing later.

This last shot puts it all into perspective. Filler on the outermost corner, 2 access panels filled and glassed.

KR2S Pitot/Static/AOA probe

2008-06-23T02:02:00.001-07:00

This Post is all about my design and build of a Pitot/Static/Angle-of-Attack probe.
My design includes the well used twin tube P/S probe in the first diagram with that of the AOA probe in the second.

The AOA works by measuring changes in pressure of two pressure ports. one facing at an angle above the relative airflow and one at an angle below it. As the angle of attack increases the pressure in the lower port increases as the pressure in the upper port drops. This change can be measured on a differential pressure gauge calibrated for various speeds and AOAs ie. approaching the stall.

The upper port can be tapped off the pitot line, in my design the pitot line feeds both the ASI and the AOA. The other side of the AOA is a port facing 45' down, the same as the commercial probe above and I included a static probe to complete the set.

First I manufactured the tubes out of 5mm brass tubing from the local hobby supply. Bent to 45' with a break line bender and soldered together with spacers made of brass offcuts.

Here is the 3 tubes soldered together. I chose to put the pitot in the middle so it was in undisturbed air at all angles of attack. The lower tube will later be trimmed flush with the bottom of the probe (roughly in line with the bend in the pitot tube). It doesn't really matter if the static is in turbulent air.

Here it is again complete.

Here you can see the piece of steel aerofoil tubing I used as a plug to make my mould. I contemplated laying FG over the steel tube and then withdrawing it after curing but thought it would be more difficult to set the probes in place.

Used plaster to make the first half of the mould. What I haven't shown is how I made this first half. I buried the steel tube as close to 1/2 deep in clay as I could and then covered with the first half of the plaster. When this was dry I inverted it, removed the clay, painted with petroleum jelly as a release agent and then filled with plaster again.

Here is a shot of the second plaster in place.

Once dry I turned it out and split the two halves apart and removed the steel plug.

I then carved a relief in both halves so I had some meat and flat surfaces to enable me to mount it. Can you see the obvious stuff-up (the first of many I'm sure)

Yes the carved reliefs are on the same side where they should be opposing.

Easily fixed with a little more carving and some clay to fill the OOPS.

Tube assembly in place, aligned and stopped with clay.

Stood up and ready to fill. Extra holes in the top to make it simpler to fill.

Not a 100% seal on those tubes, this dripped for nearly 2 hours while the resin went off. At the beginning I just scooped it up and put it back in at the top. This filler is non structural.

Yours truly scooping, and scooping and ... ... ...
Open up the mould to have a look. I like what I see. Now all I have to do is pry it out of the other half without damaging it. Clearly visible is the clay plug at the bottom to stop the resin falling through.

End profile showing the aerofoil cross section. Even more efficient when you think I'm attaching it at 45' to the airflow.

Out of the Mould and smoothed to shape. will cover with a couple of light layers of BID for strength.

This is roughly where it will be located. I am trying to maximise the distance away from the influence of the wing while protecting it from too many bumps from onlookers by sitting it behind the leading edge.

Covered with a couple of layers of BID for added strength and now installed.

And another from the front showing the AOA inlet.

KR2S Wing Shaping

2008-06-19T02:38:00.000-07:00

This series of photos shows how the wing profile is built. These photos and the wonderful workmanship courtesy of the former owner.

This first photo shows the spars attached and aligned and the 2" foam ribs have been glued into place.

These ribs are then sanded to profile with a long straight sanding board against a plywood profile at the wingtip and another at the root. Due to the wing's taper these are different sizes.

This shot clearly shows the washout that is built into these wings.

These ribs are sanded a further 3/4" below the profile to allow for a sheet of 1" foam to be placed between the spars from root to tip. The photo below shows the lower panel being glued but the top is similar. Aft of the spar is filled in similar fashion, forward of the spar larger blocks of foam are glued into place.
The whole assembly is then sanded to shape.

And sanded some more...

Until eventually you finish up with a surface like this. Ain't she a beauty?

Another angle of the finished surface.

And another ...

The instruction manual has the builder lay 2 layers of BID on the bias on this top surface at this stage. I have no photos of this but this is what it looks like once finished.

Next the whole fuselage and wing assembly is flipped over upside down, re-levelled and the whole process is repeated. View of the ribs from underneath. At this stage you can see the wing tanks have been put in place. I will do a separate post on the tanks.

Glue on more foam...
Sand to profile and cover with glass.
In this last shot you can just see the diagonal line where the edges of the glass overlap after being laid on the bias. You can also see some conduit for wing tip lights etc.

KR2S Prop Extension mock-up

2008-06-13T03:46:00.000-07:00

This set shows my mocked up prop extension.

PROBLEM ... I was given an engine cowl built to suit the O-200 engine but to fit it over the rocker covers I had to move it 4" forward as you can see in this first photo. So I knew I needed at least 4" but if I'm going to get an extension anyway would 4" be best or should I get a 6" one or even 8"? What would look the best and be more streamlined? "I feel the need for speed"

My first guess was 6". So I grabbed a length of steel pipe and a couple of these fittings from the local hardware. They are used for attaching fence posts onto concrete slabs. Luck would have it that the 2 drilled holes exactly matched the PCD of my prop flange and the larger circle fit nicely over the centre boss.

A half hour of hacking and hot metal gluing ( I wouldn't go so far as calling it welding for obvious reasons) and you have a mocked-up prop extension.

Here it is attached to the engine with the top cowl in place.

Here's another shot, this time without the cowl. As you can see I am using a length of rigid PVC conduit to test the curvature I need on the cowl. I think this is going to be really close. A bit of modification on the cowl, fill in the extra 2" at the front and it should SLICE through the air like an arrow ... well hoping so.

Here is what the real extension will look like. It is manufactured be Saber in the US.

KR2S Firewall 01

2008-06-13T02:58:00.000-07:00

This set is showing how I built the stainless steel firewall, later it will be removed and backed with Fibrefrax fire retardant sheet. I don't want a fire to burn through into the cabin structure.

This first photo shows a ply blank I made 5mm smaller than the aircraft's actual firewall. The intention is to bend SS tabs forward as a means of attaching the engine cowl. I have placed the engine mount in place as I am using it as a reference for the final layout.

This one shows the layout drawn on the SS. I later discarded every second tab as a weight saving exercise.

Measure twice, cut once.

Cut to shape...

And bend the ears forward. Before I did this I used the router to round the inner edge of my template so I didn't set up a stress in the SS while bending it.

This one shows one of the the augmenter openings and the firewall extending below the original belly line. I intend to carry a 2" deeper false floor to enclose the augmenters and it produces a pleasing line from the bottom of the cowl.

This last one just shows the Throttle and mixture cables being mocked in. In the previous you can see the gascolator temporarily placed. I left the ply in place so I can mock in all other firewall attachments by screwing into the wood prior to actually drilling the SS behind it. Measure twice, cut once....

KR2S Spinner

2008-06-13T02:09:00.000-07:00

This is my first attempt at making something out of foam and glass. I did this for two reasons. Firstly to teach myself how to work with these materials and secondly as an aid to designing modifications to a cowl I've been give.
This first shot shows a print of an existing spinner I liked the design of. I scaled it up to 10" dia and 12" long. this was glued to a piece of ply and a template cut as a guide to working the foam later on. Also in this photo is the 10" base plate I used. This was accurately centered and attached to my little home lathe.

Next I stacked a pile of polyurethane foal 12"high attaching them with either hot glue or aerosol foam filler. Both of these proved to be a poor choice as the elasticity played havoc with tooling and sanding. It was later suggested (by a FRP instructor) to use a small amount of auto body filler as an adhesive.

Here you can see I have partially finished working the foam. In the foreground you can see the template.

The finished bare foam spinner. Doesn't it look great. After this I filled the pores and any gaps with household plaster and sanded to a smooth finish.

Duct tape as a release agent, trying not to overlap is almost impossible. I learned to live with a little imperfection.

Glass cloth wetted out and cut on a template made out of builders plastic. 2 of these were made of 4oz cloth but in hindsight it turned out a little thin. Next time I'll try 6oz. {"Experimental = Education & Recreation"}

Glass and peel-ply on. The glass was a little tricky around the complex curve and I could have allowed a little more overlap.

Peel-ply off. Notice the tip where the glass bunches up. I filled this with resin/flox mixture and sanded it back.

The finished spinner in place on a mocked up prop extension. Quite pleased with this as a first attempt.

KR2S Wheels & Brakes

2008-06-09T01:48:00.001-07:00

Here are the components of the brakes. The disk, axle and mounts are all hand made by the former owner. Fantastic handy-work Gav.

Here they are all put together ...

and attached to the gear. I believe the calipers are out of a Kawasaki quad-bike.

KR2S Main Landing Gear

2008-06-09T01:29:00.000-07:00

Here you can see the main landing gear leg. It was made by laying up 40 to 50 layers of uni. Take it from me these are extremely tough. Note the brake line running internally down the leading edge.

Here is how the gear legs are attached to the forward spar.

KR2S Nose Landing Gear

2008-06-09T01:04:00.000-07:00

These first few from the previous owner.
The first (below) seems to be at a shallow angle.

This second one loks as it does now, the angle more accute.

Below is the engine mount showing how the NLG is integrates with it.

This is a more recent photo but shows the assembly installed.

KR2S Stub Wings

2008-05-28T04:26:00.000-07:00

More wonderful work from the original builder.

Attaching foam

Sanding the foam to contour.

Left wing with wing-walk showing

Wing-walk from underneath

Flip the fuse upside down and repeat.

KR2S Building the Spars

2008-05-28T04:11:00.000-07:00

Once again the wonderful work of the previous owner.

Laying out and glueing.

one side web attached

Attaching the second web.

Setting the dihedral

the full set finished

Inner spars installed.

KR2S Building the Fuselage

2008-05-23T19:02:00.000-07:00

I have added this for continuity from the start. Much of this excellent work was done by the original owner, thanks for the fantastic start Gav.

(to view larger simply click on any of the images)

KR2S Purchase and Transport

2008-05-23T18:43:00.000-07:00

Here are some photos of what the KR-2S project looked when I first purchased it. This post also includes the photos of us transporting the plane to its new home!

(to view larger simply click on any of the images)

These first two photos shot the state the original builder got to and the condition I bought it in. As you can see quite an advanced state.
The next few show us loading it onto the flatbed trailer. The mains are 7.5' wide, the trailer only 7' so I had to extend it with some wooden beams. You can also see that the cowl had been started, later I was given a pre-made cowl so this work will be lost.

Arrival at it's new home. It travelled well on the highway and suffered no damage.