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Kitty Hawk Flying Flapjack.

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  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Kitty Hawk Flying Flapjack.
Posted by Don Stauffer on Friday, July 06, 2018 9:31 AM

The KH 1:48 Vought XF5U has finally made it to my modeling bench. 

This experimental plane was a way to achieve more efficiency from a low aspect ratio wing, ordinarily not that efficient due to high induced drag.  The high drag is ordinarily due to very strong tip vortices from low aspect ratio wings.  On the other hand, short wings lead to good roll rates, and easier storage on carriers.  Vought attempted to reduce the tip vortices with huge geared props on the wing tips turning in the opposite direction to the tip vortices.  Top speed was predicted to be over 500 mph!

The plane was in the pre-production prototype phase, only a few aircraft produced, late in war, when it was undone by the rapid progress in US jets.  In spite of all those TV and book stuff, US did have fantastic prototypes as wierd as anything the Germans had.

Like typical KH kits, it seems to be a nice kit- good fit, little flash, good detail.  However, it has the typical problem with good detail- large sprue attachment points to very thin parts.  I broke one of the rudder pedal (with hangers) trying to cut it loose from the sprue :-(   Scratched another one okay and proceding on!

Don Stauffer in Minnesota

  • Member since
    November, 2009
  • From: SW Virginia
Posted by Gamera on Friday, July 06, 2018 11:16 AM

Oh that's awesome Don! I've got a kit from some limited run company, I forget which one at present that I haven't had the guts to tackle yet.

Cockpit looks good! Sucks about the broken part but glad to hear you were able to replace it. 

 

PS: Yeah, the Germans may have had the most insane secret projects but the Allies and Japan weren't too far behind..... 

"I dream in fire but work in clay." -Arthur Machen

 

  • Member since
    March, 2015
  • From: Streetsboro, Ohio
Posted by Toshi on Friday, July 06, 2018 11:25 AM

This should be a unique build.  Looking forward to more.

Your friend, Toshi

On The Bench: Revell 1/48 B-25 Mitchell

 

Married to the most caring, loving, understanding, and beautiful wife in the world.  Mrs. Toshi

 

 

  • Member since
    June, 2014
Posted by BrandonK on Friday, July 06, 2018 1:29 PM

Very cool. I've been waiting for someone to build one of these. Watching with interest.

BK

On the bench: 1/48 Kinetics E-2C Hawkeye

1/25 MPC Deserter GMC 4x4.   2%

On Deck: 1/48 Italeri Tornado IDS "Black Panthers"

 

  • Member since
    December, 2010
  • From: Salem, Oregon
Posted by 1943Mike on Friday, July 06, 2018 1:51 PM

Very interesting subject.

Even if jet powered aircraft hadn't doomed the project I would imagine the complexity of the gearing/transmission would have.

Mike

"Le temps est un grand maître, mais malheureusement, il tue tous ses élèves."

Hector Berlioz

  • Member since
    May, 2011
  • From: Honolulu, Hawaii
Posted by Real G on Friday, July 06, 2018 5:16 PM

Vought built the V-173 as a full-scale demonstrator to validate the STOL capabilities.  Although underpowered, it did prove the concept.  But when you scale up the weight, add 2X 2,000 HP engines plus "flapping" props hubs to the equation, things could have turned out not so well.  Yeah, and those big engines transmitting all that power through two 90 degree gearboxes...

A fascinating design nevertheless.  I have the Pegasus abomination and the much better Hasegawa version in 1/72.  Look forward to seeing yours built!

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Saturday, July 07, 2018 9:42 AM

Real G

Vought built the V-173 as a full-scale demonstrator to validate the STOL capabilities.  Although underpowered, it did prove the concept.  But when you scale up the weight, add 2X 2,000 HP engines plus "flapping" props hubs to the equation, things could have turned out not so well.  Yeah, and those big engines transmitting all that power through two 90 degree gearboxes...

A fascinating design nevertheless.  I have the Pegasus abomination and the much better Hasegawa version in 1/72.  Look forward to seeing yours built!

 

I have thought that the concept would work for human powered aircraft.  The aspect ratio needed for human flight is awesome.  The resulting structure has to have awesome technology.  I think a simple cable drive turning both props at same speed but counter-rotating wouldn't be that complex or heavy.  Low aspect ratio structures seem to be simpler to build.

 

Don Stauffer in Minnesota

  • Member since
    June, 2017
  • From: Winter Park, FL
Posted by fotofrank on Saturday, July 07, 2018 5:19 PM

Saw the kit today at the hobby shop where had our build day. I stroked my chin and thought "hmmm, could be fun." I'll be watching, Don.

OK. On the bench:

Way too much to build in one lifetime...

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Monday, July 23, 2018 8:32 AM

Had the first coat on main assembly yesterday, and was airbrushing second coat.  Dropped it on floor!  Knocked off both elevons!  Don't know if there was any more damage- body and elevons were wet, of course.  Hurried them into drying box to avoid damaging paint any further.

Had intended to do pix of progress- that will have to wait till I get elevons back on main body- is that the wing or fuselage on that craft- and any other damage repaired.

Don Stauffer in Minnesota

  • Member since
    November, 2013
Posted by BrynnWryttur on Monday, July 23, 2018 2:22 PM
Can't wait! This kit is on my "Want to build" list.

Prohibeo Mediocritatis

Forbid Mediocrity

  • Member since
    September, 2012
Posted by GMorrison on Monday, July 23, 2018 3:23 PM

Surviving an engine failure would have been difficult.

  • Member since
    June, 2018
Posted by E Baker on Monday, July 23, 2018 4:39 PM

GMorrison
Surviving an engine failure would have been difficult.

I was thinking the same thing. One engine goes out, and you have an instant flat-spin. Not a good situation.

  • Member since
    September, 2012
Posted by GMorrison on Monday, July 23, 2018 5:54 PM

E Baker

 

 
GMorrison
Surviving an engine failure would have been difficult.

 

I was thinking the same thing. One engine goes out, and you have an instant flat-spin. Not a good situation.

 

And the unpowered wing would dump all of its lift.

  • Member since
    November, 2005
  • From: Formerly Bryan, now Arlington, Texas
Posted by CapnMac82 on Monday, July 23, 2018 7:25 PM

Alledgedly, that's addressed with the cross-shaft, so both propellors are still turning, just with only one powerplant's worth of horsepower input.

V-22 has a similar set up, just with a much, much, longer cross-shaft.

  • Member since
    September, 2012
Posted by GMorrison on Monday, July 23, 2018 7:57 PM

Yes, one 7000 hp turboshaft engine is still potent, so long as the wing rotation transmission still functions. Otherwise, from level flight it's an interesting landing.

As I said before, a good friend of mine was a Navy test pilot, flew the F-4, F-14 and whatever else. Also flew operations from CVN-65.

Retired soon after he flew the Osprey; enough was enough.

  • Member since
    September, 2012
Posted by GMorrison on Monday, July 23, 2018 8:06 PM

Don, I really look forward to seeing more of your build.

Vought did have some innovative stuff, for sure. Rex Beisel was a gifted designer- I don't remember if he designed your subject.

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Thursday, July 26, 2018 8:52 AM

Okay, here is picture after I sanded all the junk off after dropping it on the floor. I decided to not put the tailplanes in place again (the fall impact knocked them off).  I think it will be easier to sand out successive coats of paint without them. I will finish tailplanes seperately and glue them in place after everything is finished.  Sorry for the poor depth of field- I gues f/11 was not enough.

 

Don Stauffer in Minnesota

  • Member since
    March, 2015
Posted by JohnnyK on Thursday, July 26, 2018 10:08 AM

Boy, that is one odd looking aircraft. It's hard to believe that an airplane designer would think that thing could fly.

  • Member since
    June, 2014
  • From: New Braunfels , Texas
Posted by Tanker - Builder on Thursday, July 26, 2018 12:01 PM

Aw C'mon Don !

 Do you really think I'll fall for that ? Putting a cockpit canopy on a failed pancake and painting it dark Blue ?  I'll bet your Missus was engaged in laughter after you showed her what you took out of the kitchen .

 Besides I don't think it flew well did it ?

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Friday, July 27, 2018 8:32 AM

Got another coat on yesterday.  Also made a holding rack to get a better grip on it while I airbrush, and it also works to hold it while it is drying!  This may be the penultimate coat- maybe a cleanup with a 2000 grit pad and one last coat.  Working on the props now too.  Eight big blades, wood grained!

Don Stauffer in Minnesota

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Friday, July 27, 2018 8:38 AM

Tanker - Builder

Aw C'mon Don !

 Do you really think I'll fall for that ? Putting a cockpit canopy on a failed pancake and painting it dark Blue ?  I'll bet your Missus was engaged in laughter after you showed her what you took out of the kitchen .

 Besides I don't think it flew well did it ?

 

 

My understanding is that it flew okay once you got it off the ground.  Landing it was also a pain.  I wonder how it handled at low speed.  Anyway, who needed a 500 mph prop plane when jets were approaching 600 mph.  A number of US prop fighter experiments went nowhere.  All of these things were just hedges in case the jets didn't really prove out.

 

Don Stauffer in Minnesota

  • Member since
    December, 2010
  • From: Salem, Oregon
Posted by 1943Mike on Friday, July 27, 2018 12:15 PM

Don,

My old neurons seem to recall that plane from way back when - either I read about it or saw it in a newsreel (unlikely since I was only 4 in 1947). This is a strange looking aircraft for sure! I'm following with interest.

BTW, F/11 would have been about as small an aperture as you would have wanted to use. Diffraction begins to creep in at that opening albeit not usually too noticeably. I'm assuming you're using a digital device to capture your images. The image you suggest does not have enough depth of field may suffer from camera/phone movement and/or lack of focus. One or both of the latter is probably the problem - not the f stop.

Mike

"Le temps est un grand maître, mais malheureusement, il tue tous ses élèves."

Hector Berlioz

  • Member since
    January, 2010
Posted by CrashTestDummy on Friday, July 27, 2018 12:42 PM

Tanker - Builder

Aw C'mon Don !

 Do you really think I'll fall for that ? Putting a cockpit canopy on a failed pancake and painting it dark Blue ?  I'll bet your Missus was engaged in laughter after you showed her what you took out of the kitchen .

 Besides I don't think it flew well did it ?

 Don, I think Tanker was referring to your specific example.  I'm sure it 'flew' well when being flipped on the griddle, but that final hard landing made some noise.  So the pilot couldn't see around all that wet paint?!?  Wink
 
Can't wait to see the finished kit.  I've almost ordered this kit several times.
 
Regards,
 
Gene Beaird,
Pearland, Texas

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Saturday, July 28, 2018 6:35 AM

1943Mike

Don,

My old neurons seem to recall that plane from way back when - either I read about it or saw it in a newsreel (unlikely since I was only 4 in 1947). This is a strange looking aircraft for sure! I'm following with interest.

BTW, F/11 would have been about as small an aperture as you would have wanted to use. Diffraction begins to creep in at that opening albeit not usually too noticeably. I'm assuming you're using a digital device to capture your images. The image you suggest does not have enough depth of field may suffer from camera/phone movement and/or lack of focus. One or both of the latter is probably the problem - not the f stop.

 

No, the camera was on a tripod.  And, this was a flash shot- at the distance I was at with my flash attachment the exposure was pretty short!  And, I found out when I went to take the next picture next day, the camera had accidentally been set (aperture priority) to f/5.6 (wide open).  I must have bumped the control wheel during setup.

 

Don Stauffer in Minnesota

  • Member since
    December, 2010
  • From: Salem, Oregon
Posted by 1943Mike on Saturday, July 28, 2018 10:29 AM

Don,

Not to belabor this OT subject but there's nothing in the image you posted to which we're referring that IS in focus. That, to me anyway, means that A) the tripod setup was bumped or moved somehow when the shutter was released or, B) the camera/phone did not focus properly for the exposure or, C) My eyes are playing tricks on me.

Anyway, interesting thread. With your skills at this game it'll turn out to be a fascinating model.

Mike

"Le temps est un grand maître, mais malheureusement, il tue tous ses élèves."

Hector Berlioz

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Sunday, July 29, 2018 11:05 AM

Discovered something in the instructions regarding the prop blades.  There are two sets of blades, obviously a different set for the two different prop shaft housing and hubs.  But, even though you build two different sets, when you glue those assemblies to the aircraft it does not say which goes on the right and which on the left.  The lower numbered (36-39) blades are on the unit that mounts on the left side, the higher numbered (40-43) go on the unit on the right.

 

Don Stauffer in Minnesota

  • Member since
    May, 2011
  • From: Honolulu, Hawaii
Posted by Real G on Sunday, July 29, 2018 4:29 PM

The props on the XF5U counter rotated; the port unit clockwise, the starboard anti-clockwise when viewed head-on.  The purpose was to cancel out tip vortices to cut drag and get better low speed control.

The prop blades were staggered because they were set up like a helicopter rotor; i.e. they were designed to allow the prop "disc" to tilt out of the plane perpendicular to the driveshaft.  This was to improve the thrust line for the extreme approach angles for takeoff and landing.

BTW, on the actual aircraft, the starboard prop did not have the oval Hamilton Standard logos for some reason.  All prop blades had the stenciling on the cuffs as well as the white tracking diamonds on the wood sections.

HTH 

  • Member since
    April, 2015
Posted by Mopar Madness on Sunday, July 29, 2018 7:24 PM

And I thought the Germans had some crazy looking ideas!  Surprise Nice build thus far! 

Chad

God, Family, Models...

At the plate: 1/48 GWH Fw 189 A-1 Nachtjager

On deck: 1/48 Bronco IF-17

In the hole: Who knows!  

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Monday, July 30, 2018 8:06 AM

Real G

The props on the XF5U counter rotated; the port unit clockwise, the starboard anti-clockwise when viewed head-on.  The purpose was to cancel out tip vortices to cut drag and get better low speed control.

The prop blades were staggered because they were set up like a helicopter rotor; i.e. they were designed to allow the prop "disc" to tilt out of the plane perpendicular to the driveshaft.  This was to improve the thrust line for the extreme approach angles for takeoff and landing.

BTW, on the actual aircraft, the starboard prop did not have the oval Hamilton Standard logos for some reason.  All prop blades had the stenciling on the cuffs as well as the white tracking diamonds on the wood sections.

HTH 

 

Oh, nuts!  I just put the decals on the starboard props and sealed them with glosscoat!

 

Don Stauffer in Minnesota

  • Member since
    May, 2011
  • From: Honolulu, Hawaii
Posted by Real G on Monday, July 30, 2018 11:50 AM

Don,

Don't sweat it; symmetry is prettier!  Just enjoy building your wacky model and we'll look forward to seeing it at completion!

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