KR2S Fuel Tanks

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 Wing Shaping

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.