Hombebuilt B-29/Stratocruiser

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Workhorse

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Mar 6, 2010
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Southern Spain
I’ve been thinking if the engine I have could propel a downsized b-29. I mean, we have a 35 hp 4st direct driving a 48” propeller giving about 110 Kg (242lbs) static trhust I guess.
Let’s have an airframe with 6.8m (22.3ft) wingspan. 43 sqft (4sqm) wing area. Aspect ratio 11.35. MTOW 250 Kg ( 551lbs) giving a wing loading of 12.8 lbsqft (63kgm2). Empty weight is 100 Kg, 220lbs (engine itself 101 lbs, 46 Kgs). Pilot and parachute another 220 lbs. 68 l or 18 gal of fuel . Fuel burning from 8-10 l/h, 2.1-2.6 gph.
Let’s again imagine a stratocruiser airframe we can fit in. Remove engines and fit the one I have in a blunt nose alike a bearcat. Put a RV3 canopy, and an underseat full of bead foam. The stratocruiser airfame would give you about 18” in the waist, 29” tall without canopy, 25”wide and still a cushion of 12” under the seat between spars.http://39th.org/39TH/images/cutaway/cutaway.gif. Karman fairings blending wing root and fuselage. Single wheel retract.
We can see the root airfoil http://www.ae.illinois.edu/m-selig/ads/afplots/b29root.gif give us room enough for intended fuel.
My question is if I could build a composite airframe weighting 120 lbs. If I could have fowler flaps, wich would be the take off run, stall and cruise speed?. With given tip airfoil http://www.ae.illinois.edu/m-selig/ads/afplots/b29tip.gif would we need wing washout?.
For trim there would be an adjustable angle of incidence device for the fixed part of the horizontal stabilizer.

Thanks for watching.
 
Last edited:

Bart

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Apr 13, 2007
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Hmmm.

Show and tell us more about that engine and propeller combination, please.

I like the bead foam seat idea. Light, cheap, comfortable, keeps you warm at altitude, as long as you keep those pesky beads contained.
 

JimCovington

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Mar 30, 2009
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Burlington, VT
If you're asking, the answer is "no." Anyone with the extensive composite construction & design experience required to build a 120lb airframe (without engine) doesn't need to ask. It's a huge challenge.

Here are some comparable examples of very small airplanes (without engines):
Carbon dragon ~160 lbs
KR-1 ~220 lbs
Cassuutt racers ~300 lbs
AR-5 ~350 lbs

Two side notes:
To mimic the flight characteristics of a B-29, you can be a bit heavier - I'd guess up to a 180-200 lb airframe without engine.

Why not use that engine to make a 1500lb, 4 engine 140hp B-29 replica? THAT would be beyond cool. Wingspan would be closer to 35 feet or so - you could still fit in in a T-hangar, and take a friend along!
 

RacerCFIIDave

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Feb 8, 2008
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Asheville, NC
Hmmm.

Show and tell us more about that engine and propeller combination, please.

I like the bead foam seat idea. Light, cheap, comfortable, keeps you warm at altitude, as long as you keep those pesky beads contained.
The beads in bead foam is actually contained within a polyurethane matrix...

The beads only "get out" if you break it...and then only from the area of failure...

Dave
 

WonderousMountain

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Anyone can make a light airplane, with the right tools.

See what acheiving your goal would actually take before altering it on anyones advice.

Wonderous Mountain
 

JimCovington

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Anyone can make a light airplane, with the right tools.
If by "light airplane" you're referring to the proposed design, I disagree.

"Light airplane" and "120 lb carbon airplane capable of handling a 100lb 35 hp engine" are two completely different categories.

First, it's a challenge to DESIGN a 120lb carbon airframe - using any tools you want. Significant experience is required. That right there takes it out of the "anyone can do it" category.

Just because nobody has done it before doesn't mean it can't be done. But it's a really good indication that it's extraordinarily difficult, and it's very likely that it's not something that "anyone" can do.


Your daily dose of reality & eternal wet blanket,

Jim
 

lr27

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I think it won't look right with one engine in the front. Plus that engine is pretty heavy. Use 4 of something like what they use in a Cri Cri. I guess then you HAVE to make it an ultralight or you'd need a multi engine rating?

The canopy won't look right either. So do a Super Guppy and tint the canopy so it looks like the fuselage.
 

Dana

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Actually, a private pilot can fly any single seat experimental aircraft, whether he's rated for it or not.

Why not use four 20HP R/C model radial engines? Or six of them and four jets and build a B-36... :)

I still like my idea of a miniature single seat Hughes Hercules (Spruce Goose) with eight tiny engines...

-Dana

Thinking for yourself is like most addictive behaviour. It is frowned upon by all right thinking people and is bound to get you killed sooner or later.
 

JimCovington

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Actually, a private pilot can fly any single seat experimental aircraft, whether he's rated for it or not.
Getting waaay off topic...

Really? Didn't know that. Also didn't know the number of seats mattered more than the number of engines.

Didn't one of the EAA magazines run an article recently about getting required special pilot certification for turbine aircraft? Or was it Kitplanes?

I don't know the details; don't own any turbines.
 

Dana

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Well, it's only for experimentals. I don't know if it extends to anything requiring a type certificate, but, for example, a PP-ASEL can fly (not sure if the requirement is just solo or single seat) an experimental gyrocopter, or seaplane. Hmmm... that means I could fly a Cri-Cri without getting a multi rating... hmmm... :)

Ah, just found the link... you can do it if he aircraft's operation limitations don't mention any restriction:

The FAA regulations do not require a person flying solo in an experimental aircraft to hold the specific category/class rating for that aircraft. However, the operating limitations issued to the individual aircraft as a part of its airworthiness certificate may include the requirement for the pilot to hold the approprate category/class rating even when flying solo.

When carrying passengers, the pilot must hold the appropriate category/class rating or privilege for the aircraft.


-Dana

The missionaries go forth to Christianize the savages-- as if the savages weren't dangerous enough already.
 

lr27

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Somewhere on the web is a video of a development model by a British company for a large seaplane. I think the model is less than 50 foot span, as I recall, and carries only the pilot. Not very sure about the span.
snip

I still like my idea of a miniature single seat Hughes Hercules (Spruce Goose) with eight tiny engines...

-Dana

snip
 

K-Rigg

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Round Rock TX
Well, it's only for experimentals. I don't know if it extends to anything requiring a type certificate, but, for example, a PP-ASEL can fly (not sure if the requirement is just solo or single seat) an experimental gyrocopter, or seaplane. Hmmm... that means I could fly a Cri-Cri without getting a multi rating... hmmm... :)

Ah, just found the link... you can do it if he aircraft's operation limitations don't mention any restriction:

The FAA regulations do not require a person flying solo in an experimental aircraft to hold the specific category/class rating for that aircraft. However, the operating limitations issued to the individual aircraft as a part of its airworthiness certificate may include the requirement for the pilot to hold the approprate category/class rating even when flying solo.

When carrying passengers, the pilot must hold the appropriate category/class rating or privilege for the aircraft.


-Dana

The missionaries go forth to Christianize the savages-- as if the savages weren't dangerous enough already.

Another question:

If one was to use two engines to power a counter rotating propeller, does the pilot need a multi engine rating?
 

Dana

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Another question:
If one was to use two engines to power a counter rotating propeller, does the pilot need a multi engine rating?
Again, if it's a single seat experimental, no. If not, I suspect yes... though if you got your rating in such a plane it'd be limited to "centerline thrust".

-Dana

But it's NOT an ASSAULT Weapon, it's a DEFENSE weapon!
 

Workhorse

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First, thank you all for your replies. I've decided to put aside my project of a low aspect ratio flying wing given I doubt this powerplant could delivery power enough and there are some stability issues I'm not happy with also . I will post some photos as I receive some spares and start the first bench tests.

So, got one engine, a shop, and plenty of materials. The B-29 wing seems very interesting since there is a root thick airfoil wich can lead if I'm not wrong to a really stiff and light wing spars. But it is a complicated wing to build accurately.

Then I'm going for a Strojnik S-4 Laminar Magic alike.

I've designed a wing spar of a douglas fir core and gl1 plywood laminate. The upper beam is a 2x3 cm (about an inch) and the lower 2x2. There is a dihedral in the tappered section. Each side there are two 5mm (1/5 in), 5 inches tall plywood sheets, 2.7 m long. Then the outer sheets come in lenghts of 1.35 m, 1m, and 0.65m.
Part numbered 3 between beams is the same fir but vertical grain oriented along the first 0.65 m of the spar. Several vertical strips are also arranged along.
The total weight of wood with no glue is 6 Kg, 13.2 lbs.
The weight of ribs, hinges and counterweights can amount 2.5 kgs, 5.51 lbs else. Wing skings 8.8 kgs, 19.38 lbs. (these are four layers of 10 oz. fiberglass oriented 45º made over a glass, vinilester and postcured).

Total 17.3 Kgs, 38.14 lbs without glue

I plan to link both wings with 16 strips of 4130 in the first 0.3 m out of the wing in each one. These strips are 12/16 inch tall, 1/16 thick.
Two AN26 clevis used to make wings detachable.

Wingloading is 60 kg/m2 or 12.32 lbs/sqf. at mtow.
Each surface is 1.85 m2, 19.85 sqft. Span 5.4 m.
Total wing area 4.17 m2, 44sqft.
Mtow 250 Kg, 550 lbs.
Estimated empty weigth 120 Kg, 264 lbs.

I think I can accurately build it with a NACA 66-215 but, not being an engineer don't know if this spar disposition could stand a 66-212. Do you know a better airfoil for this purpose?, a climb rate of 300-500 fpm is far good for me, just want to go from A to B as fast as I can.

Any comments are welcome, and thank you in advance.
 

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57Marty

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Mar 11, 2007
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Central Coast of California
Have you seen this B-29 RC? It has about a 20'wing span, rudder is as tall as the "Pilot", 4 engines. The size of this would not have to be enlarged that much to make it big enough for a real pilot. [video=metacafe;804337/worlds_largest_model_rc_plane/]http://www.metacafe.com/watch/804337/worlds_largest_model_rc_plane/[/video]

Another one to take a look at is this 1/3 scale B-17 that is close to flying.
Pilot Building 1/3th Scale B-17 | Pacific Flyer

Interesting ideas.
Marty57
 

WonderousMountain

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Have you checked the elasticity modulus of wood compared to the fiberglass. I expect they'll be a lot different, and either the wood or the skin will end up carrying almost the entire load.

Also, Douglass fir is not my idea of a good aircraft wood. It's usually readily available and easily worked though.

Actually, this is one of the better propositions I've seen here so far.

Looks good.

Wonderous Mountain
 
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