The Fleabike

[kasper]

And the query on undercarriage position is relatively variable for you - you can make up a second set of undercarriage tripods to move the wheel positions later if you find them too far back.  Moving 100mm would be relatively easy with a set up you have drawn.  

[duncan_rtfm]

Hi Kasper,

I briefly considered a wing tank, but dismissed the idea because I thought it would affect the wing movement in flight.  But if, as you say, this is not the case, then I'll definitely look into this.  What would be a good material for this?  There is a thread on one of the other forums about plywood gas tanks - suitably sealed, of course.  Lots of varying opinions.  Major drawback seems to be weight.  But I guess aluminium would be preferable, except that I have no sheet ali skills or tools.

 

Thanks.

Edited July 9, 2021 by duncan_rtfm

[duncan_rtfm]

I spoke to Jared Smith from RAAus yesterday about the Fleabike, and he put me on to Bill Oakes who doesn't live too far from me.  I'll contact him on Monday and discuss when would be a good time for him to drop by and inspect the fuselage.

 

Duncan

[kgwilson]

Moulded fuel tanks from glass reinforced vinylester resin are easy to make to whatever shape you need. Make it in 2 pieces, the base being what holds all the fuel and a fairly flat top with the peak being where the filler cap and fuel gauge sender is if you want one. If the tank is able to be seen the fuel level can also be seen. You can make baffles to reduce sloshing and mould a sump for the offtake and drain.

[facthunter]

If there's room between your legs and under the seat why not put the tank there? It's close to your C of G and easy to fill etc and relatively safe.. If it's done in sheet ally it could be structural and easily removed. You will need a small fuel pump for take off back up Slosh baffles are always a good idea. it's also low down and fits in with the fleas "no ailerons" philosophy. Nev

[onetrack]

Doesn't sound like a good position for a fuel tank to me. In the back of my mind, you always need to be aware of what might happen in a crash - and having a fuel tank some distance away from yourself, and the engine, has to offer an improved level of safety. Even just being covered in raw petrol, without it actually being ignited, is painful.

[facthunter]

You don't have much choice but any twin you fly has heaps of fuel plumbing below your seat n the wing carry through. Behind the motor has to be close to the worst place possible. A conventional high wing  has the best options but the flea wing move s  and is very high up compared to most things, tending to tip it on the  ground like a double decker bus.. Nev

[duncan_rtfm]

I've been looking at the fuselage, and yes, there is plenty of space directly in line with the CG inside the box.  Easy filler cap jutting through the fuse side comfortably below the knee joint.  And since the seat is screwed on (not bonded), I should be able to get the tank in/out.  This will work.  Now I just have to Google how to make a composite tank.  Ha ha.

 

Thank you so much for these gotchas guys.  I really appreciate it.

[facthunter]

I'd make it out of sheet AL  tig welded with baffles and shaped to not oil  can.. Can be quite light weight . Shape the bottom so all fuel is used regardless of attitude(within reason) Nev.