Flying Flapjacks

[Scott Kenny]

I saw in a video that the Skyrocket, a twin-engined pre-WW2-airplane where the props passed very close to each other, had difficulties when the props turned towards each other. It lost the efficiency of the mid-section of the wing. When they made the props turn away from each other, the problem was solved.

That also happened to the P-82 Twin Mustang. The props coming down onto the center wing completely negated the lift of the center wing!

I think to recall that the V-173 had also tests of the props turning to each other and away from each other. Any info known about the difference in performance for the V-173?

Not that I've seen, but I also haven't done any deep dives for it.

 

[Prophet141]

Looks like this concept;

http://www.secretprojects.co.uk/forum/index.php/topic,2925.210.html

Could a jet-flapjack have been made that exhausted cold gas from the compressor stage along the wingtips, sort of like a hovercraft, in order to act as a "virtual" winglet?

 

[Scott Kenny]

Could a jet-flapjack have been made that exhausted cold gas from the compressor stage along the wingtips, sort of like a hovercraft, in order to act as a "virtual" winglet?

Maybe?

That would have been a 1980s or 1990s development, IMO.

 

[Firefinder]

Maybe?

That would have been a 1980s or 1990s development, IMO.

It was first done in the 1950s on standard planes, the A5 Vigilante had it as well as the F4.

So it might have been possible.

Issue would have been getting the money and interest to do so.

 

[Prophet141]

Maybe?

That would have been a 1980s or 1990s development, IMO.

Oh, absolutely. I wasn't considering it as a 1940-50s era technology, though blown flaps and boundary layer control didn't take too long to emerge after that. I was considering it more in the context of a later ground attack flapjack for use by someone like the US Marines.

 

[Foo Fighter]

Looks like a very useful platform for an unmanned AWACS or umnanned subhunting mission.

 

[Scott Kenny]

It was first done in the 1950s on standard planes, the A5 Vigilante had it as well as the F4.

That's just flap blowing, which is very different from seeing a stream of blown air as a winglet or control surface all by itself.

IIRC that wasn't visualized until the F-18 HARV in the early 1990s.

Looks like a very useful platform for an unmanned AWACS or umnanned subhunting mission.

I've been very surprised that none of the companies working for the DARPA TERN and the USN follow-on program haven't used a Flapjack airframe.

 

[Firefinder]

That's just flap blowing, which is very different from seeing a stream of blown air as a winglet or control surface all by itself.

IIRC that wasn't visualized until the F-18 HARV in the early 1990s

Yeah both the A5 and F4 had air blowing both over the flaps.

And the FORWARD EDGES of the control surfaces, the A5 even had it on the rudder, to enhance their crappy low speed agility and lift into something that can land on a CV. Was an outright PITA to maintain which is while later planes lack it. With the Navy going so far as to tell Lockmart NO we don't want it on the F35C which is why that has a longer wing.

But the experience from those informed the HARV program in the mid to late 80s which was very much a Let See how Far we can push this type of program.