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Old Jun 06, 2012, 05:08 AM
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Joined Jan 2012
124 Posts
Tech One EPP P51 = terrible plane

I got a Tech One Fun Trainer and a Tech One P51 figuring that they would allow a pick it up and fly after crash experience. That has not been the case. The Fun Trainer will break in a crash due to the weak nose. The P51 won't break now that I have repaired it with CF, but it flys so poorly that I wish it would!

The Fun Trainer I have eventually gotten to fly well and it is now fun to fly. Overall, I am not impressed with the fun trainer. I doubt that a true beginner would be able to get it to fly well without help, but it can be adjusted to fly ok. (The most important modification is to hold the battery in and back by wrapping the tape all the way around - the battery holder won't last long.) The Fun Trainer can do some aerobatics. My son likes to watch the wing dihedral change from nearly folding up on normal loops to going flat on outside loops. I have a lot of aileron throw which allows rolls and flying upside down. Those are fun things to do with the Fun Trainer. Take off and landing practice is also fun and that is why I got the plane. The Fun Trainer is actually fun to fly now even though it is not very crash tolerant due to the weak nose. The P51, however, is a different story.

The P51 has been very disappointing. First, it was quickly apparent that the ailerons are too stiff. If you do build one, leave off the servo arm extension. I had to take mine off after a few flights and it is not as easy to do after assembly. Later I cut the hing line in short sections to allow more motion - that helped a lot in allowing the ailerons to move, but did not help the plane fly well. Now to the flying - It can fly ok just gently flying it around, but pulling any g forces causes a spiral dive. The second such incident broke the nose off and I stiffened the fusalage with CF and it has not broken since. Still, the same thing happened - It was not possible to recover from the dive, even by expert pilot friends, so we looked for reasons and found them. The main reason was that one wing was much stiffer that the other. This causes the aileron on one side to change angle more than the other under stress. Hence any significant g forces cause variable differential wing lift and that results in a death spiral into the ground.

I stiffened the wings with CF and added diagonal bracing top and bottom. The modifications reduced the problem to the point that flight was possible and and recovery from the spiral dive was possible with adequate altitude and spin recovery technique. I also found that moving the battery back so that the CG is just behind the main spar helped. Still the plane could not do a loop without rolling out. I stiffened the tail. That helped some, but the plane still rolled out of loops. It is really not fun to fly a plane that cannot pull some g forces without instability

Yesterday it nosed in wildly shortly after takeoff from the second flight of the day - inadequate altitude to recover this time. Well the plane survived, as it has many times since I reinforced it, but this was the last straw for the motor. I have broken a lot of props and now a motor and spent a lot of time. This plane was not worth the carbon strips I wasted on it except as a lesson in how important stiffness is in airplane flight quality. Although the plane is durable now that I have reinforced everything, it is not fun to fly and will never be a dog fighter as it was intended to be. I will be taking the components out of it.

I tried posting reviews on Nitro Planes site twice over the last couple of weeks and they were never posted. I made the second one at least sound a bit favorable by noting the durability and the fact that just flying around gently is fine. I called them about this - they only post reviews they like. They suggested posting elsewhere, so here it is... Lesson learned - never buy a plane unless it has a lot of great reviews. No reviews likely means that the plane has problems and negative reviews have probably been rejected.

I may have gotten a lemon with the big difference in stiffness between the right and left wing, but even after fixing that, the plane was just poor. Poor aileron design and implementation. Poor quality control to have such difference in wing flex. A flexy and small tail. I doubt many people looking for reviews on this plane will find this post, but I felt that some warning should be posted.

I would guess from the fact that people seem to like the Tech One 3D planes that they are better. It appears that they fly more slowly and have larger wing and tail area per weight carried would help a lot with the stress/flex and control situation. Clearly they are better designed than this Tech One P51.
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Last edited by xcski; Jun 06, 2012 at 05:13 AM. Reason: need to clarify that this is for the Tech One P51
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Old Jun 06, 2012, 05:12 AM
manual flying apologist
Adidas4275's Avatar
United States, CA, Fresno
Joined Mar 2011
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Thanks for the heads up on the trainer

I can fly 4 ch no problems.

How did you reinforce the nose?
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Old Jun 08, 2012, 02:06 AM
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United States, CA, Pleasanton
Joined Apr 2002
435 Posts
TechOne Metal Motor Mount ?

Guys,

I'll be ordering either the SU-31 or Yak from NP.

I am looking for a US dealer that stocks the optional aluminum motor mount.

Any ideas appreciated.

TIA.

:harry
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Old Jun 10, 2012, 09:26 PM
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Bloosee's Avatar
United States, CA, San Diego
Joined Jan 2012
2,508 Posts
The 35 inch Yak54 is VERY fast! It flies pretty good but is a real handful to 3D fly, I must say though other than the wood motor mount, it's durable.. I've since ordered the SU-31 and the 35 inch Extra. They are cheap planes, go together quick and are basically disposable practice planes.
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Old Jun 11, 2012, 10:38 AM
Former Futaba employee
Joined Aug 2006
1,178 Posts
I am working on a swift this week and could use a little help, what glue for the canopy?, replace 1 or both of the carbon rods in the wing for a couple little thicker carbon tubes? I really want 26 gram servo's in it and have some of the solar d658's that I am thinking of using?
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Old Jun 11, 2012, 12:29 PM
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Kansas City, MO
Joined Jan 2000
696 Posts
I just ordered the 43 inch yak form nitroplanes. How well do the control surface hinges work?
Any mods needed?
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Old Jun 11, 2012, 12:45 PM
Registered User
United States, PA, Catawissa
Joined Jul 2011
359 Posts
Quote:
Originally Posted by Jerry Brown View Post
I just ordered the 43 inch yak form nitroplanes. How well do the control surface hinges work?
Any mods needed?
Hinges works fine once you lose them up a bit by flexing them back and forth. Sleeve carbon tubes over elevator and rudder rods for better control. Also check the main wing airfoil, make sure its not flat on the top. I used to work for epphobby and we found this issue once.
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Old Jun 11, 2012, 12:47 PM
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United States, PA, Catawissa
Joined Jul 2011
359 Posts
Quote:
Originally Posted by Adidas4275 View Post
Thanks for the heads up on the trainer

I can fly 4 ch no problems.

How did you reinforce the nose?
Brush or smear thin epoxy glue on the inside part of the nose and firewall.
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Old Jun 11, 2012, 02:57 PM
WickedFunRC's Avatar
Utah USA
Joined Jun 2002
2,232 Posts
To loosen up the EPP hinges on these even further I mask or mark about 2" sections at the ends and a couple in the center on the back side of the ailerons hinges. I'll then lightly sand the unmasked/marked areas being careful not to sand through them. I then smear a bit of Goop glue at the extreme ends of the aileron hinges to help prevent a tear from starting. I smear the glue on the extreme ends of the rudder and elevator hinges too.

The rudder hinge is really prone to tearing. Once the glue is dry I'll apply a small strip of Scotch Extreme tape across the ends of the hinge while the aileron is fully deflected so that there is a bit of slack in the tape.
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Old Jun 11, 2012, 03:25 PM
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United States, PA, Catawissa
Joined Jul 2011
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Quote:
Originally Posted by khen View Post
To loosen up the EPP hinges on these even further I mask or mark about 2" sections at the ends and a couple in the center on the back side of the ailerons hinges. I'll then lightly sand the unmasked/marked areas being careful not to sand through them. I then smear a bit of Goop glue at the extreme ends of the aileron hinges to help prevent a tear from starting. I smear the glue on the extreme ends of the rudder and elevator hinges too.

The rudder hinge is really prone to tearing. Once the glue is dry I'll apply a small strip of Scotch Extreme tape across the ends of the hinge while the aileron is fully deflected so that there is a bit of slack in the tape.
Great tips, thanks!
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Old Jun 11, 2012, 04:19 PM
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United States, PA, Philadelphia
Joined Dec 2011
2,176 Posts
Hey Wolfewinde, I am not stalking you but TechOne and GWS are both my favorite planes in my fleet!

Just found this thread, no wonder you spent less time on the GWS thread!
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Old Jun 12, 2012, 09:03 AM
My Co-Pilots Rock!!
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United States, FL, Clearwater
Joined May 2011
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Heya, Vince

Good to see you over here

On the Swift - I crashed mine once at about a 45 degree angle - the carbon rods were fine but the motor mount failed, so I would reinforce that and not worry about the carbon rods

Wolfe
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Old Jun 12, 2012, 11:08 AM
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United States, OR, Salem
Joined Jan 2012
287 Posts
The motor mount on my Yak (ARF) failed the first time it took an easy nose first "landing." I cut out the old one, made one out of 3/16 ply and moved it and the battery tray back .5 inch to give the motor a bit more protection. I changed to a 1300 lipo and the COG is back where it should be. I have knocked the mount loose but it has not broken since. I also had to cut parts of the aileron hinges to make them flexible enough. Before I cut them I was stripping out servos every flight which usually ended in another nose first landing. No problem now since I switched to MG servos.
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Old Jun 12, 2012, 11:10 AM
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United States, PA, Philadelphia
Joined Dec 2011
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I also had trouble loosening up the live hinges in my 44" Yak. It resulted uneven throws on two ailerons. I did the similar thing as khen mentioned, I marked 1.5" sections at the beginning/end of the ailerons and two 1" sections in the middle, but I actually cut through the unmarked sections, and then applied hinge tape on the back (up) sides of both ailerons. But hinge tape does not stick well on the TechOne's EPP. This mod give me a lot of throw on ailerons, I can do 2 to 3 rolls in a second if I want to. I have maybe 20 flights so far and the mod holds.

Last Sunday while I was building the 36" Yak for my friend, I used the tips shown in the build video from Nitroplanes. I just simply folded the ailerons all the way up and then put some books on top of them to keep them in the back to back position for 5 minutes. The result is satisfactory, she has more throws than needed. I set the high rate at 80% on aileron and she is still handful in high speed, but a lot of fun!
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Old Jun 12, 2012, 11:23 AM
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United States, PA, Philadelphia
Joined Dec 2011
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Yes, the motor mounts on the two Yaks I built also broke. A piece of RC grade ply wood took care of that easily.

Also, the recommended CG on the 44" Yak is way too forward. I used a 71g motor, 60A ESC, 3S 1600mah battery, and 2oz of lead to achieve the recommended CG. She flew okay but would not hover and was difficult to do a harrier landing, which resulted a slightly nose-in that broke the motor mount. So I removed all the lead, downsize to a 40A ESC, removed the LG and now the CG is about 1" behind the recommended spot. She flies much better.
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