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Old Oct 03, 2008, 06:59 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Build Log
257" B-36D Scratch Build 6 a turning and 4 a burning

Well,
This is the start of my thread on my B-36D project. I started the design 8 years ago with the intent of it be 256" with 6 gas engines, but after doing all the calcs I realized that the plane would weigh over 110 pounds because I would need 45 pounds of ballast to off-set the engines weight at the trialing edge of the wing. Now with electric motors I can build a 257" B-36D and hit about 51 pounds. I have drawn the entire plane in both 3D max, and AutoCAD so I can scale the drawings to any size I need. The plane will have 6 AXI 4130/20 Motors turning Zinger 3 blade 20" props, in testing I get about 5 minutes at full power and 12 at 65% cruise power. I have just got all of my plans printed out on my plotter to start cutting wood. The retracts are going to be Century Jet Models, Inc. and be Scale b-36 gears. I have been using Ecalc and it looks to be spot on with what I am seeing in testing.

Will try to update weekly or better.

Thanks, DAG
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Old Oct 03, 2008, 09:42 AM
Bi-Planes
Tim Farrar's Avatar
Houston Texas
Joined Apr 2006
1,589 Posts
I'm here Dag, !!!!

This is going to be awsome !!!!

Seeya, Tim
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Old Oct 03, 2008, 10:27 AM
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Warsaw - Poland
Joined Oct 2006
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Subscribed!

You are crazy DAG!
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Old Oct 03, 2008, 10:36 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Quote:
Originally Posted by alchemique
Subscribed!

You are crazy DAG!
Yes I am, but you may be talking about me hitting the 51 pounds. I had a 178" B-29 with 4 4-stroke engines, the whole thing with fuel only weighed in at 41 pounds. 236" with electric should be do-able.

I have ordered the plywood for aircraft spruce and will start cutting next week.

Thanks, DAG
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Old Oct 03, 2008, 10:37 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Quote:
Originally Posted by Tim Farrar
I'm here Dag, !!!!

This is going to be awsome !!!!

Seeya, Tim
Thanks Tim,
Just wondering, did you ever get your power back? Hope all is well.

DAG
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Old Oct 03, 2008, 03:10 PM
Aerodynamically challenged
3Deranged's Avatar
3D World, Florida
Joined May 2005
3,180 Posts
The real one was nicknamed" Aluminum Overcast" ,this one will be " Balsa Overcast"!
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Old Oct 03, 2008, 04:25 PM
SENTA A PUAAA!!!
Wilian Amaral's Avatar
Brazil, RJ, Miguel Pereira
Joined Apr 2007
919 Posts
Here I am too!!!

Anxious to see this project flyin'
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Old Oct 03, 2008, 07:56 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
This may sound crazy, but because I have 99% of all the parts drawn, there will not be much guess work, I plan on having this plane in the air by June 2009, that’s if the boss (my wife) does not catch how much I am spending, batteries and motors are over 2.5k

I will post more of the 3D renderings, what is vrey cool is every part I have drawn gets put into a 3D model then I build it in 3D, if the parts fit in 3D then they will fit when I cut the kit out of wood.

This is something very cool to me because I have wanted to build the B-36 for over 30 years, for the last 15 I have been getting drawings and photos, I even have this old control-line kit that was made in Japan (though I have never built it). And here I am now about a week from cutting wood.


Rock On!

DAG
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Old Oct 10, 2008, 02:13 PM
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Sabrejock's Avatar
Winnipeg, MB Canada
Joined Jan 2000
2,419 Posts
Would using a shaft from the motors to the T/E help with the awful prospect of so much ballast? A bearing at the rear and gimbal style motor mount at or ahead of max thickness would seem to be helpful. Tex.
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Old Oct 10, 2008, 02:33 PM
Bi-Planes
Tim Farrar's Avatar
Houston Texas
Joined Apr 2006
1,589 Posts
Hi Dag, What do you think of Tex's idea ?

That might be a good way to think about doing your motors so you dont have a bunch of nose weight.

You may have your own ideas already though...

I got my power back a week or two ago now !!!! Thank God !!!

I dont remember for sure because I am already taking advantage of it !!!!
You dont miss it until you dont have it !!!

Thanks for asking !!
Seeya, Tim
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Old Oct 10, 2008, 07:00 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Quote:
Originally Posted by Sabrejock
Would using a shaft from the motors to the T/E help with the awful prospect of so much ballast? A bearing at the rear and gimbal style motor mount at or ahead of max thickness would seem to be helpful. Tex.
Tex,
That is a great idea, I have thought about it on gas power to get the weight at the front of the wing. My wing loading at this point will be about 26oz, that's at 52 pounds so the plane is going to fly great, however if I end up over 55 pounds I will have to look into this. What makes me not like the idea is keeping everything straight so I don't end up with vibration from the shaft and the connections. Do you know of any shafting that would work at about 14” in lenght and turn an 18-12 3 blade prop?

Attached is my weight and moment chart. You can see the motors are kind of close to the CG that the true off-set is about 2 pounds of ballast, the rest of the ballast is from the main-L-gear, H-stab and the V-stab.

Tim,
Glad you are back with us that have power. I will post more 3D rendering of the nose, and hopefully show you some parts cut out by Monday.

Thanks all, DAG
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Last edited by dag214; Oct 10, 2008 at 08:07 PM.
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Old Oct 11, 2008, 07:22 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Welllll,
After thinking more about what Tex said about shafting the motors I think it is 110% the way to go. It is funny how you get tunnel vision after designing a plane for a bunch of years. The weight savings will be about 4.5 pounds taking my ballast down a ton. I had a design for shafting G-26 engines and these electrics can't be any harder than those.

Attached is the start of the re-design of the nacelles.

This site is cool because I get different eyes looking at my designs and builds.

Thanks, DAG
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Old Oct 11, 2008, 08:35 AM
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Sabrejock's Avatar
Winnipeg, MB Canada
Joined Jan 2000
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DAG, might I suggest that you look at the shaft/prop as a unit and connecting with a 1:1 (or whatever) ratio gearing or belt drive. I think this would make alignment and vibration conrol easier. Tex.
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Old Oct 11, 2008, 10:45 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,895 Posts
Quote:
Originally Posted by Sabrejock
DAG, might I suggest that you look at the shaft/prop as a unit and connecting with a 1:1 (or whatever) ratio gearing or belt drive. I think this would make alignment and vibration conrol easier. Tex.
Tex,
I tested a G-26 with soft mounts and a direct shaft on a prop hub I made myself. It had a 6061 T6 1/2" shaft. The shaft had 3 bearings and was 26" long. The soft mounts allowed the engine not to bind on the bearings. It kept things very light. With this layout, shaft, bearings, and extra bearing bulkheads I am saving 2.65 pounds of ballast. The G-26 did shake a bunch, but I think I will make a test nacelle and see what happens.

Thanks, DAG
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Old Oct 11, 2008, 01:12 PM
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AmpAce's Avatar
North by Northwest
Joined Nov 2003
2,422 Posts
Dag, I was having the same thoughts as Tex about gearing the prop drive down some with a belt drive. You could turn the scale props with a smaller motor, and probably save some more weight, overall. The belt drive system should also be easier to keep straight, and vibration free, since your connection to the prop shaft would be via a belt. You could just have a straight shaft running through the nacelle, with a bearing at each end, and probably one near the drive sprocket, if it doesn't end up near the end of the shaft. This kind of a system would give you more flexibility as to the size and type of motors you use. I've also heard that a belt drive system for electrics makes a much more realistic sound than a direct drive motor. I've never heard one, though.

There is a wealth of information available from SDP-SI I sent for their free catalogs, and was very pleased with the information and products they contain. Here's a link to their website: http://www.sdp-si.com/

What a magnificant project you have taken on! I remember as a kid, just after WW II, seeing B-36s flying over our house, out in the hills in western Oregon. Sometimes there were as many as six in a formation. The windows in the house would actually start vibrating before you could hear the engines in the house. The flights would usually go over quite low above the hills, so the noise was amazing.

Best of luck with this project, I'll be watching!

AmpAce
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