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T28 Trojan

Old 01-13-2009, 04:09 AM
  #101  
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Originally Posted by benovisoff View Post
Well everyone says a 3-blade 10X7 has more power and pulls more amps, which I use both of, and they only pull max 23 amps. Maybe 11X5 might do the trick.

Yeah, an increase in pitch really starts to spike the amps.

just so happens I was doing this math earlier. Stock prop is 9.5x7.5 so using the PLF formula PLF = (D^2)P

9.5^2 x 7.5 = 676.875

So lets say a 10x7 has a prop loading factor of 700 (10 x 10 x 7) and works great right where you want it. An 11x5.5 would be even less (11^2 x 5.5 = 665.50) and you would have more thrust at the expense of less prop speed (high end).

A 10x10 would put you at 1000 - 30% more load than the 10x7 - which is danger dog territory IMO. Frankly I think you might stress the airplane at those speeds. When I yank and bank I alread see a little deformation - a 10x10 is a pylon racer prop and the airframe might just buckle.

Just a heads up, mang. No one wants to see you melt the front half of your plane off in mid flight
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Old 01-13-2009, 04:23 AM
  #102  
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alright. 12X10 it is! why on every post where it says flight it goes to a reference link?
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Old 01-13-2009, 04:28 AM
  #103  
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Originally Posted by benovisoff View Post
alright. 12X10 it is! why on every post where it says flight it goes to a reference link?
Mike Parsons, the head honcho around here - I think he is experimenting with a glossary modification that will link common words to a, well, a glossary of terms. Its an effort to improve the edumacationality of this intarwebsight directilly.

Actually all kidding aside I think its pretty cool. I've always said there are so many know it all fartypants around here that a Wiki would explode and grow like a fungus! They'd have to triple check my entries though lol

GRU
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Old 01-13-2009, 04:32 AM
  #104  
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LOL! I have finals now, so I don't get to fly, just study. I hate it. There should be a final on rc, I'd be the only passing grade!
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Old 01-14-2009, 01:58 AM
  #105  
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The pics won't work. I tried 9999999999999999999999999999 time to put my pics up, but it wont take, I and saw the specific thread from mike parsons about it, yet it still won't work.




look below. nevermind.....

Last edited by benovisoff; 01-14-2009 at 03:28 AM.
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Old 01-14-2009, 03:27 AM
  #106  
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These are a few pictures 'fore the maiden. But how do I post a vid, they are much better.
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Old 01-15-2009, 09:47 PM
  #107  
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Cool about the 3 blade prop, i want one on my Trojan but i also heard the ESC gets over ridden by the extra amp draw. I prefer to keep mine stock . Have not flown for about 3 days now, weather problems.

Ive lost 3 home made parachutists now using my bomb dropping device .

Happy Flying.
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Old 01-16-2009, 01:21 AM
  #108  
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No. Not at all! It pulls about 20 amps on the 30amp esc, so I just picked up a 12X8 prop at the lhs.
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Old 01-16-2009, 02:51 AM
  #109  
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Originally Posted by benovisoff View Post
No. Not at all! It pulls about 20 amps on the 30amp esc, so I just picked up a 12X8 prop at the lhs.
2Q -

1. How much current does stock prop draw?

2. How does performance differ with 3 blade 12 x 8?
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Old 01-16-2009, 03:10 AM
  #110  
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Stock about 19. I used the 12X8 on the T-28. I hit 25 amps and it shook violently. I have the same setup on my SS, yet it worked like a charm and only drew 22 amps? I don't get whats wrong?
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Old 01-16-2009, 03:58 AM
  #111  
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Originally Posted by benovisoff View Post
Stock about 19. I used the 12X8 on the T-28. I hit 25 amps and it shook violently. I have the same setup on my SS, yet it worked like a charm and only drew 22 amps? I don't get whats wrong?

22 amps on the same motor? Hard to imagine man. In fact only drawing 5 more amps after going from a 9.5x7.5 to a 12x8 is a little weird too.

The shaking is probably because the prop is out of balance.
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Old 01-16-2009, 04:03 AM
  #112  
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the five more is on the SS. It pulls 25 on the trojan at 7/8 throttle, yet shakes violently with that 30amp esc
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Old 01-16-2009, 07:18 AM
  #113  
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Originally Posted by benovisoff View Post
These are a few pictures 'fore the maiden. But how do I post a vid, they are much better.

post it to Vimeo.com first and then link it - they allow you to post in high quality so its better than YouTube.

GRU
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Old 01-17-2009, 12:22 AM
  #114  
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I have a big prob with it. I put the 12X8 prop on it with the 480 pz and 30 amp esc, and it shook violently. I tried 3 motors all 480s and 2 escs, and it all shook violenty. But one motor didn't even work although it worked on my ss...

Last edited by benovisoff; 01-17-2009 at 04:17 AM.
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Old 01-17-2009, 04:41 AM
  #115  
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Originally Posted by benovisoff View Post
I have a big prob with it. I put the 12X8 prop on it with the 480 pz and 30 amp esc, and it shook violently. I tried 3 motors all 480s and 2 escs, and it all shook violenty. But one motor didn't even work although it worked on my ss...
Seems like a lot of the T-28 even in stock trim have motor vibration at full throttle.

I have not had a chance to fly mine yet but it has the same vibration.

Anyone else had the vibration and solved it 100% ?


Clint
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Old 01-17-2009, 05:44 AM
  #116  
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figured it out! the prop was too big and drawing too much power that the motor mount was able to take, and it ripped it!
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Old 01-17-2009, 12:05 PM
  #117  
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Originally Posted by benovisoff View Post
figured it out! the prop was too big and drawing too much power that the motor mount was able to take, and it ripped it!
2Q

1. Was damage to motor mount obvious? (could you see damage or wiggle mount?)

2. Did you repair or replace mount?

I'll take a look at mine and report back.


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Old 01-17-2009, 03:45 PM
  #118  
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the motor mount did not move when I pulled on it myself. But the violent vibrating and eventual breaking of the motor mount only when I changed the prop from a 10X10 to a 12X8. When it started to do this with the 12X8, I changed it back to the 10X10 (I did not know the reason for the problem at the time). It wasn't literally until 1/2 a second after the motor mount ripped did I realize the problem. If you have the vibrating the motor mount is insecure or you have too much power for the motor mount to handle. I thought it was the motor so I changed the motor. It wasn't the motor. I thought it was the esc because it still did it, so I tested another esc. Still did it. I ripped the motor mount and knew what the problem was.
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Old 01-17-2009, 04:19 PM
  #119  
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2. So did you replace or repair the motor mount?
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Old 01-17-2009, 04:33 PM
  #120  
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I am going to get another plastic one today, but I am in the proccess of ordering an aluminium one. I am pretty sure that the motor mount couldn't handle the power, but I don't quite know if the motor mount couldn't handle it, or the screws it the fuse came apart. I will test this too when the aluminium one comes
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Old 01-17-2009, 04:41 PM
  #121  
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Originally Posted by benovisoff View Post
I am going to get another plastic one today, but I am in the proccess of ordering an aluminium one. I am pretty sure that the motor mount couldn't handle the power, but I don't quite know if the motor mount couldn't handle it, or the screws it the fuse came apart. I will test this too when the aluminium one comes

Got it - Thanks. If you get a chance, please post pics of where the old one broke so I can check the same location on mine for signs of stress or impending failure.


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Old 01-17-2009, 06:49 PM
  #122  
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here is where they broke.... The prop was the problem. I tried it again with another motor mount and same result. But if your battery won't even give full power, say it was down to 12.28 like mine, and you give full power, it will give more power than the 10X7, but just not enough to make it vibrate. If you don't care about flight time too much and like power but don't want to buy a new motor mount, prop, motor, and possibly esc, then drain the batt a little almost around 12.2, and then on full power a 12X8 will fly it like a 11X6. Drain it just by leaving it on, or putting it on half throttle while holding it will drain it quicker.
I drilled those extra holes myself because I thought the pz480 motor was the prob but the mount did not fit an eflite 480, and I didn't have an adapter so I drilled those holes myself
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Old 01-17-2009, 07:11 PM
  #123  
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Beginning to realize why there are so many vendors telling T-28 aluminum motor mounts.
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Old 01-17-2009, 07:35 PM
  #124  
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I'm gettin' one this week. Theres a man on rc groups who has them for sale for the eflite and pz motors, and for the spitfire. He posted his adress and email and paypal stuff on the thread though, not too smart....
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Old 01-18-2009, 05:53 AM
  #125  
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Originally Posted by cbatters View Post
Seems like a lot of the T-28 even in stock trim have motor vibration at full throttle.

I have not had a chance to fly mine yet but it has the same vibration.

Anyone else had the vibration and solved it 100% ?


Clint
Yes, I have solved it. Balance your props, even the stock ones. When you put a huge 3-blade 12x8" whomper on and it is out of balance, there is no big mystery why the motor mount gives out. 12x8 is kinda redonkulous from the start for a plane which is typically 30oz AUW, especially one that has such a purpose-built airframe (trainer).

GRU
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