Operational Pancake.

[PR19_Kit]

After finding a Hasegawa XF5U-1 Flying Pancake kit at the Scottish Nats, at a very good price I might add, I want to build an operational F5U-2 to pair up with the Whiffed two seater Pancake trainer I built during lockdown.



Naturally the operational version will have the same turbo-props as the two seater, but will need longer wings (of course.....) to lessen the form drag and to improve its range. 

The question is where do I increase the span, inside or outside the props? The two variants are shown below, in my scabbed together graphic of the real plastic part.



I have my own idea which version looks best but I'd pleased to hear what the rest of you think as well.

[AeroplaneDriver]

I would go for the increase outside the props.  Longer wing inside the props is going to have some potential negative handling effects, and at the very least would mean bigger rudders and V-stabs.  Plus I think it looks better! 

[Steel Penguin]

yurp, like what he said
outside the props looks cooler

[Dizzyfugu]

I'd also add span outside of the props. In real life, moving the props would mean changes in the gearboxes, higher torsioanal forces, and more or less a new construction. Just adding lift area outside of the aircraft's core makes IMHO most sense.

[Gondor]

I agree with all the above, also easier to do 

Gondor

[Wardukw-NZ]

Agreed with my colleagues 
It looks far cooler and its far simpler to do and as Dizzy said..a massive increase in work to basicly rebuild the entire air frame.
Go to with the outside Kit   

[PR19_Kit]

Wow, a pretty overwhelming vote there. Thanks very much. 

Needless to say I was going for increasing the span INSIDE the props. 

But I'll go with the majority, and I'll make the 'tips' more curvy, they're a bit block-like in my graphic.

[perttime]

Having the propellers at the wing tips would look cool (different? crazy?) - BUT model building and real world engineering issues might keep me from contemplating it too much.

[Flyer]

Wow, a pretty overwhelming vote there. Thanks very much. 

Needless to say I was going for increasing the span INSIDE the props. 

Well I for one am disagreeing with the majority, I much prefer the look of the inside the props version. Although I can see the problems pointed out by Dizzyfugu regarding the gearboxes etc... I can remember reading something about the prop rotation outside the wingtips eliminated the vortex of air spilling out from under the wing creating much extra lift as it was virtually increasing the wingspan anyhow. If there is any wing outside of the props you would loose some or even all of that benifit. Something to think about?

[PR19_Kit]

That was what I was thinking about when I wrote the techno-babble about '......lessen its form drag......'

Zimmerman's idea was to do exactly as you said Flyer, the props generated large vortices around the vestigial 'wing tips' and reduced the drag tremendously. And it really worked, as demonstrated by the small scale V-173. Sadly the real Pancake never got a chance to show how well it worked at full scale.

[McColm]

I disagree with the majority, go for the inner engines, then you can expand the wing area and add additional engines if required.  The second fuselage.
I know build one yourself McColm to prove the point.

[rickshaw]

I prefer the extended wing tips.  Why?  Because it would be easier to do.  You don't need to modify anything other than the airframe.  Otherwise you need the extend the drives from the engines and that brings with it torsional stresses which could get messy.

[PR19_Kit]

Of course if I was Tophe I'd do one side with the extension inside the props and the other side with it outside the props. 

[zenrat]

Inside.  Because it is less immediately noticeable.

[PR19_Kit]

Inside.  Because it is less immediately noticeable.

Hmm, I hadn't thought of that before, but you're right. 

And there wouldn't be THAT much more engineering for the prop drives. It'd just need the cross shafts extending a bit.

If it's displayed alongside my trainer Pancake the difference would be more noticable of course, unless the viewers were blinded by the trainer's  colour scheme. 

I haven't thought of a colour scheme for the operational Pancake yet, but it can't be Midnight Blue, that'd be too much like the OOB kit. Grey/white? Camo? Who knows?