Contest – Build Off: 60” wingspan Tupolev ANT-25 - RC Groups
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Jan 07, 2007, 01:16 PM
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jsfrench's Avatar
Contest

Contest – Build Off: 60” wingspan Tupolev ANT-25


I decided to try this after watching a History Channel program on the Russian aircraft industry in the ‘30s and ‘40s. They showed the ANT-25 and it looked like a good project.
This plane set a non-stop record from Moscow to North America in 1937.
See the following for a brief history of the plane:
http://www.oldbeacon.com/gallery/bat...tchelor-18.htm

So far I have found a 3-view but no fuselage cross sections.
The wingspan is 111 feet and the length is 43 feet!
I guess I will use a sailplane airfoil for the wing using Compufoil.

Thanks to portablevcb of www.manzanolaser.com for sponsoring the buildoff.
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Jan 07, 2007, 01:29 PM
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http://mkmagazin.almanacwhf.ru/avia/ant_25.htm

Here is a link with superb drawings. Good luck with the project!

Istvan
Jan 07, 2007, 02:12 PM
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jsfrench's Avatar
Quote:
Originally Posted by Istvan Noszvai
http://mkmagazin.almanacwhf.ru/avia/ant_25.htm

Here is a link with superb drawings. Good luck with the project!

Istvan
Istvan:
Большое спасибо!!
This is great site! Now I have no excuse for not jumping right in to this project. (After the American football playoffs of course.)
John
Jan 07, 2007, 02:52 PM
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Kiwi's Avatar
Have a look on "The Plan Page" also for help on the cross sections.
Jan 08, 2007, 10:57 AM
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jsfrench's Avatar
Quote:
Originally Posted by Kiwi
Have a look on "The Plan Page" also for help on the cross sections.
Thanks Kiwi, I can use all the help I can get. Looking forward to your "Mystery" entry.
John
Jan 08, 2007, 01:46 PM
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Kiwi's Avatar
There was also a book I read about this flight which included quite a few photos. The title was something like "How Russia Fooled The World" or something along those lines, it's basic plot was that the whole thing was hoax and there were two aircraft, one which started the flight and another which ended it after having taken off close to the US coast.
I'm too slow a builder to join in!
Jan 19, 2007, 04:13 PM
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jsfrench's Avatar

adding 1/8 in breaks for the laser cutter.


This is the first time I have tired making plans to be laser cut. I am using Turbocad v12 and I was having a devil of a time adding the 1/8 in breaks that hold the parts to the sheets until I found this thread:
https://www.rcgroups.com/forums/showthread.php?t=286490

The rubber stamp circle method by Jim Robinson works great.
Jan 20, 2007, 04:39 AM
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John,

a very pretty solution I was looking for. I'm a TCad user as well and I'll try the method.

Prekrasnij camolot! (I have no cyrillic keybord)

The Ant 25 is one of my favourites and I hope to have time to build one too.

Istvan
Jan 29, 2007, 09:40 PM
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jsfrench's Avatar

working on the Wing.


The Compufoil package creates a plan of the wing and a set of ribs. But I have to make the spars and webs and wing tips. I have tired some 3D packages and RHINO looks pretty good. I tried the demo and then did the ribs and spars as an exercise. I plan on using RHINO on the fuselage. This computer work is taking a lot longer than just cutting the parts by hand, but it is kind of fun. I am trying for a self aligning wing, with the jigs being the front and rear spars.
Feb 03, 2007, 12:27 PM
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Martin Hunter's Avatar
You're saving me the time of designing one of these myself It's nice to see another fan of Tupolev's work. What's your target weight? I forget the exact numbers, but I recall working out the wing area at 60" and it was fairly miniscule - like 220 sq in or something. Keep the wing loading down and you won't have to worry about tip-stalls even with that tapered wing planform, though.

Martin
Feb 03, 2007, 03:37 PM
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jsfrench's Avatar
Quote:
Originally Posted by Martin Hunter
You're saving me the time of designing one of these myself It's nice to see another fan of Tupolev's work. What's your target weight? I forget the exact numbers, but I recall working out the wing area at 60" and it was fairly miniscule - like 220 sq in or something. Keep the wing loading down and you won't have to worry about tip-stalls even with that tapered wing planform, though.

Martin
Martin,
>What's your target weight?
The short answer is I don't know, I am a rookie.
I am just going to try and build as light as possible, weigh it, MotoCalc it , then add a motor and battery.
I was thinking of this plane as a glider. Due to crashing experience, I am putting in 2 degrees of washout and plan on having the leading edge blunter at the tip end. Also 2 aileron servos so I can do spoilerons. I have done a few plans-built planes, and scratch wings, but this is the first time I have tried designing a complete airplane. For ideas, I am relying on, amomg others, rcgroups , my first laser-cut kit - a Balsacraft fw-190, a Skyshark kit and Keith Shaw's ideas(http://members.aol.com/kmyersefo/page3.htm).
John
Feb 16, 2007, 09:30 PM
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jsfrench's Avatar
Well, I'm finding out that getting a 3-view into CAD is not so easy. Since this is a learning experience I am in no hurry. I am making some progress on the fuse but there is still a lot of work to do. I was wondering, is anybody using a version control to handle the drawing changes? After a while it is hard to keep track of which is the correct drawing change.
Feb 16, 2007, 10:50 PM
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portablevcb's Avatar
Version control is almost a personal thing. I found that putting the date on them works best.

charlie
Mar 08, 2007, 01:26 PM
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jsfrench's Avatar
Still working on CAD. Learning more about snaps and trim-line. This is the 3rd time on this rear wing spar and I think that I will have one that fits this time. I are using a straight top wing surface so the notches will be perpendicular to the top of the spar(which I didn't do the first time). Also the spar is not perpendicular to the ribs so I added a slight amount to the notch width.( which I didn't do the second time) .
Apr 02, 2007, 04:29 PM
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jsfrench's Avatar

finished with CAD


Finished with the design work and sent of the dxf files to Charlie.
Since I don't have much room in the fuse, I decided to pick the power unit first and ask questions later.

I am going to use a 28mm outrunner at 100 watts.
WING AREA = 281 sq in. = 1.95 sq feet
Flying weight = 24 oz / 1.95 = 12.3 oz / sq ft
power = 100 watts / 1.5 # = 66.6 watts/#

Weight so far for radio rcvr, motor, ESC with connector, prop, prop adp, spinner, tp1320 bat with connector,dime bag of servos,wheels,axles,
1/16 x 36 music wire(should cover linkage weight),
and 2 servo extensions = 9.8 oz

balsa assume full sheet 10 pound weight
1 sheet 1/32 x 4 x 24 balsa = .28 oz
4 sheets 1/16 x 4 x 24 balsa = .56 x 4 = 2.24 oz
2 sheets 3/32 x 4 x 24 balsa = .83 x 2 = 1.66 oz
1 sheet 1/8 x 4 x 24 balsa = .56 x 4 = 2.5 oz

aircraft plywood
1 sheet 1/64 x 4 x 24 balsa = 1.00 oz
1 sheet 1/32 x 4 x 24 balsa = 1.42 oz
1 sheet 1/16 x 4 x 24 balsa = 2.31 oz

covering
Econocote 500 sq in x .00165 oz/sq in =.825 oz ~ 1.0 oz
Total = 12.41 oz
hardware + wood + covering =12.41 + 9.8 = 22.21 oz
.5 oz fiberglass fuse = = 2 oz?
Total = 24.21 oz?
allowance for over estimate of wood = glue used?


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