Tuesday, 26 January 2016

Week 233 - Cowling Part 7

Hours to date: 2168.75

Hi all and sorry for the lack of posts but I've been away on holiday and the resin only just arrived yesterday.

I got the final 3 layers of chopped strand mat on last night. 

Just got the wooden supports to make up and glue on and the top mold should be finished.

While it sets I will carry on with the long range fuel tank.

As I'm planning to fly this bird to Oshkosh she will need some more range so I've designed a 35 litre tank which will go just behind the pilots seat.

The fuel is simply pumped into the left wing tank when that is emptied (via the return line for that tank).

As far as weight and balance goes it should be okay as the tank is right up to the back of the pilots seat and only goes a little way into the baggage area so it should be like having a heavy pilot with a little more luggage type of feel when it is full.

Putting the fuel inboard means there is no parasitic drag penalty - unlike Pete's bomb which is external (although to be fair to him he has done this to comply with the LAA guidelines for it to be jetisonable - something I do not need to worry about as I will only be using it outside of UK airspace).

It is an approx rule that the drag penalty for external tanks is equal to 25% of the fuel that they carry. Of course when that fuel is burned you still have the same drag penalty. An internal tank gets around these inefficiencies but of course will still have a penalty when full with the reduced climb rate and slight increase in induced drag (due to the extra weight) but both of these disappear when the fuel is burned off.

Pete's bomb holds 25 litres, my tank will hold at least 35 litres and give a total no reserve range of over 700 nm which should be plenty for those long legs over Greenland and to Canada (headwinds permitting).

More about the tank when I start making it.

Tail up while I figure out the long range tank - looks like it will work!

Think I could be an extra on Star Wars? Just need that lightsaber...

Final 3 layers of chopped strand mat are on. Wooden supports to come next.