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Old May 19, 2011, 01:50 PM
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Build Log
Tu-134

I'd like to start a 1/20 scale Tu-134A project. And keep this blog to organize my thoughts and references for myself.

General Plan:
- rough prototype first to test flight characteristics, CG, power requirements, weight lifting capabilities, building technologies. The prototype can use simple props.
- then start modifying the prototype to finalize the technology for various components and the power system, test things like retracts, flaps.
- once all decisions are finalized, make the final clean version.

Inspiration
- Neffwaffe's planes. Unfortunately he only publishes on Youtube, very limited info.
- A bunch of demondriver's planes. These are simple but probably too heavy for 55mm EDFs:
-- DC-9-51 http://www.rcgroups.com/forums/showthread.php?t=1175678, 4.2lb, 70mm HET typhoons from EJF.com, not yet flown
-- DC-9-32 http://www.rcgroups.com/forums/showthread.php?t=1422967 len: 62", ws: 48", AUW 3.5 to 4lbs, above EDFs, not finished yet
-- BAC 1-11 http://www.rcgroups.com/forums/showthread.php?t=1178995 len: 69", ws: 69", AUW 5.5lb, above EDFs
- MD-83 http://www.rcgroups.com/forums/showthread.php?t=1310441. This one is nice and very close, unfortunately unfinished. Plans or at least instructions at http://www.scale-parkflyer.de/out/PD...83%20Teil1.pdf, http://www.scale-parkflyer.de/out/PDF%20MD83%281%29.pdf. Ws: 1300mm (51"), len: 1670mm (65"), AUW 1100g (39oz), ELE 55mm with 4100kv. In the instructions and video they user 3600kv.
- B727 http://www.rcgroups.com/forums/showthread.php?t=976207. Very close, 2mm depron, and actually flies. Ws: 1.4m, len: 1.6m, AUW: 1.16kg, started with C20 3600kv on GWS55 on 3s 3000mAh 2X10.5A draw 560g static thrust; then moved to 4S 2200mAh, GWS EDF55, 3900kv BLM005.
- A319 http://www.rcgroups.com/forums/showthread.php?t=418206, GWS50 of Feigao 5300, flight post 702, retracts, AUW 690g with a 3S 1500mAh. Also another variant with HACKER E10 28L 5500kv.
- A320 3mm depron http://www.rcgroups.com/forums/showthread.php?t=336041. Bigger but nice technique. Len 1.90m, ws 1.70m, AUW 1.5kg,
- MD-83, excellent technique: http://www.rcgroups.com/forums/showthread.php?t=1300995, photos at http://rpmtech.smugmug.com/Other/Md-83 worth studying in details.

Plans, etc.
- Workaround photos http://scalemodels.ru/modules/photo/...t_cid_557.html, http://scalemodels.ru/modules/photo/...t_cid_137.html
- VR workaround http://www.google.com/url?sa=t&sourc...sSyIag&cad=rja
- paper model http://www.avsimrus.com/f/paper-mode...134-19688.html (also http://www.paper-avia.com/en/modelz/wars/ww3_t/191#top3 but that might be behind a paywall). It is fairly useless as the proportions are all wrong
- Photoshop PSD files 600dpi http://only-paper.ru/forum/75-7405-1 (the actual files http://rapidshare.com/files/439053622/Tu-134_01.psd
http://rapidshare.com/files/439053855/Tu-134_02.psd). These came from magazine Aviation and Time (Авиация и Время) March 2010 http://journal.knigka.info/2010/05/0...el-2010g..html
- A Sketchup model by MindTheGap http://sketchup.google.com/3dwarehou...2b42a5&ct=mdrm. This guy also has a few more color schemes. Could be a good start to develop design in sketchup.

Specs for the model
- Wing span: 29m/20=1450mm
- wing area: 115m^2/400=28.75dm^2
- length: 37.1m/20=1855mm (fuselage length 33.17m/20=1658mm)
- weight hopefully 1.1kg, aim under 1.3kg
- wing loading 1100kg/28.75dm^2=38g/dm^2; max: 1300g/28.75=45g/dm^2
(UPDATE: Yeah right. More like 1800g in reality)

Power system considerations
- Scale intake diameter: 45mm
- scale exhaust diameter: 35mm
- scale max nacelle diameter: 61mm horizontal, 70mm vertical at the bulge (see post 77)
Q: with the above parameters, would 55mm be more efficient than 50mm despite the restrictions of the intake ?
- I'd like to have a fairly quiet fan. A clone of Wemo Midi 90mm on my EuroFighter is very nice in that respect. Wemo 50mm was quiet if I remember correctly.
- Hyperflow is not quiet, people say (should check with friends)
- http://www.bphobbies.com/view.asp?id...5&pid=A3507978 looks promising. Then for the motor http://www.hobbypartz.com/elite-400-...ess-motor.html or http://www.hobbyking.com/hobbyking/s...dProduct=10927 or http://www.hobbyking.com/hobbyking/s...dProduct=10932.
They also have similar motors at hobbypartz but with 3mm shaft.
- http://www.hobbypartz.com/88e-adf55-300l-kv4300.html is nice and light but has a lip - hard to imbed into a nacelle.
- Wemo 50mm with 4800kv Wicked motor http://www.donsrc.com/cart/index.php...d&productId=95

Various other decisions
- wheels:
mains: 930x305mm/20=46.5mm x 15mm
front: 660x200mm/20=33mm x 10mm

CG should be between 96mm and 60mm from the trailing edge of the wing post 79 (UPDATE: first flight was close to 120mm)
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Old Jun 23, 2011, 04:40 PM
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Power System

Purchased
Fans: http://www.bphobbies.com/view.asp?id...5&pid=A3507978
Motors: http://www.hobbypartz.com/elite-400-...ess-motor.html

Wheels:
Main http://www.bphobbies.com/view.asp?id...22&pid=T290733
Nose: had some lying around from AK-Models Zero
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Old Jun 23, 2011, 07:16 PM
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Bulding starts

After playing around with SketchUp and making some progress with the nose and its structure, I decided to start building to test the concept.
I decided to use the method very similar to the Scale-Parkflier model
http://www.rcgroups.com/forums/showthread.php?t=1310441

My intention is to eventually use 3mm Depron Aero, but for initial testing I'm going to use food tray covers (at least for the nose).

The internal structure is made with BPHobbies 5mm foam. It is covered on both sides with a thin plastic film, which makes it much more sturdy.

Not sure yet what to do with the nose cone, whether to sand it from a single block of foam or cover it with 4 pieces of food tray.

Next step is to sand the corners and start gluing some skin on.
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Old Jun 24, 2011, 12:15 AM
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Covering Nose

The inner structure is sanded, and I started covering the nose with skin.
Food box covers made from a tough foam with nice surface and it bends easily without breaking. And best of all - it is free, just harvest it during your lunch.
The weight at the end of the day is 28g.
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Old Jun 24, 2011, 01:08 AM
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Excellent work Sergey! Great progress!
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Old Jun 24, 2011, 11:55 PM
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Nose covered.

Another day, more progress.
The nose is completely covered. Now need to spackle it and sand a little. Then time to build the "chin" radar dome.
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Old Jun 25, 2011, 12:07 AM
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Wow Somebody's damm good at Bending & working with depron! I might have to give up sanding!
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Old Jun 25, 2011, 12:14 AM
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Depron is fairly brittle. But those food trays are really nice.
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Old Jun 25, 2011, 12:14 AM
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I see your going with the glass nose version Sergey.
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Old Jun 27, 2011, 08:15 PM
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The Radar Dome

I had a chance to work on the "chin". Actually, I think it looks more like a "beard". While making it, I noticed that the 3-views are incorrect. The photographs show the beard to be rectangular in plan, with parallel walls crossing the bottom panel lines. But on the plans, it is trapezoid in shape with front part more narrow and the walls being right on the panel lines.
That would explain the deviation I saw on the photo-matching. I will have to go back and fix it in the sketch-up model. But later.
It is more important now to continue forward and work out the middle and the rear sections of the fuselage. To do that I need to make a number of decisions:
- elevators or flying stab ? (that will determine the position of the servo)
- how to attach the nacelles ? (I'll need to provision some structure for that in the fuselage)
- one big wing or two plug-in consoles ? And in the second case - pug the wings at the fuselage or make a large center section up to the LG and plug the panels at the LG ?

Comments are welcome.
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Old Jun 28, 2011, 12:36 AM
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Quote:
Originally Posted by SergeyK View Post
I had a chance to work on the "chin". Actually, I think it looks more like a "beard". While making it, I noticed that the 3-views are incorrect. The photographs show the beard to be rectangular in plan, with parallel walls crossing the bottom panel lines. But on the plans, it is trapezoid in shape with front part more narrow and the walls being right on the panel lines.
That would explain the deviation I saw on the photo-matching. I will have to go back and fix it in the sketch-up model. But later.
It is more important now to continue forward and work out the middle and the rear sections of the fuselage. To do that I need to make a number of decisions:
- elevators or flying stab ? (that will determine the position of the servo)
- how to attach the nacelles ? (I'll need to provision some structure for that in the fuselage)
- one big wing or two plug-in consoles ? And in the second case - pug the wings at the fuselage or make a large center section up to the LG and plug the panels at the LG ?

Comments are welcome.
Looking superb Sergey! Mr Tupelov would be proud of you! As for a stabilizer or stabilator a stabilator will excert more control forces at the pivot point but be easier to link with just one servo. I don.t use stabilators because of my fear of overcorrection or too touchy up & down movements but if you program the right ammount of exponential in your radio & limit your travel or movment of the stabilator you should be fine Sir.
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Old Jul 01, 2011, 11:38 PM
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Sergey, awesome work.
looks like you will be done before my MD11 ver2.Havent worked on it in weeks. But dont worry I am still going to let you know before the maiden

I gotta get sketchup and mess with it.


SUBBED!!!
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Old Jul 07, 2011, 05:25 PM
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I agree with Him Sergey! ^

Any new pics?
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Old Jul 07, 2011, 08:18 PM
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A little progress with the SketchUp. Spent a lot of time thinking what to do with airfoils. After a lot of reading around decided to stick with NACA 2412 throughout the wing (a little stretched in some places), with +2 at the root through the LG (so that the flat bottom is almost horizontal), then uniformly turning to -2 at the tip.

Drew the wing, then struggled a lot with the LG gondola. Still does not look right in places. At the moment, it is not worth fixing it, better to figure out how to build it and adjust the foam with sandpaper.

The wing fairing was easier, but it is hard to tell how close it is to the prototype. I looked at a lot of photos, seems close enough given the different airfoil.

Now I need to decide on the wing spars and the foam structure of the LG gondola. I've decided to have two separate plug-in wings similar to the Airbus 320 construction (mentioned in the first post).
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Old Jul 07, 2011, 09:19 PM
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Quote:
Originally Posted by SergeyK View Post
A little progress with the SketchUp. Spent a lot of time thinking what to do with airfoils. After a lot of reading around decided to stick with NACA 2412 throughout the wing (a little stretched in some places), with +2 at the root through the LG (so that the flat bottom is almost horizontal), then uniformly turning to -2 at the tip.

Drew the wing, then struggled a lot with the LG gondola. Still does not look right in places. At the moment, it is not worth fixing it, better to figure out how to build it and adjust the foam with sandpaper.

The wing fairing was easier, but it is hard to tell how close it is to the prototype. I looked at a lot of photos, seems close enough given the different airfoil.

Now I need to decide on the wing spars and the foam structure of the LG gondola. I've decided to have two separate plug-in wings similar to the Airbus 320 construction (mentioned in the first post).


Marvelous work as always Sergey!

My God that's a huge TU-134 printout!
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