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Old Jun 02, 2012, 10:32 PM
The Crash King
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United States, OH, Richfield
Joined Mar 2010
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Do you think this will work for a mild aerobatics flight pattern?
Elevator: HS-82MG
Rudder: T-Pro MG-90s
Ailerons: T-Pro MG-90s

Do you think the rudder should be a better servo?
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Old Jun 03, 2012, 01:24 AM
Retired USAF
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USA, SD, Piedmont
Joined Jul 2005
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I've never used the TP servos but the specs look plenty good, as long as you're happy with the resolution and centering--go for it! FWIW, the HS-82MG has the same electronics as the HS-81MG...still don't understand why Hitec blew an opportunity to improve what should be a great servo by not improving the centering. Might be a cost issue but the price difference between the -81 and the -85 is not that much. The HS-81 is strong, reliable and inexpensive...but I've stopped using them for elevator servos. See how yours centers and use it if it's one of the good ones.
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Old Jun 03, 2012, 09:27 AM
The Crash King
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United States, OH, Richfield
Joined Mar 2010
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Quote:
Originally Posted by THX-181 View Post
The vibration issue seems to stem from two areas...
1) Prop/motor balance
2) Weak nose structure/motor mount

Check out page 134 post 2000 of this thread for the fix I used.
Also,
Some folks are using metal motor mounts alone with good results.
Here's a link... http://www.headsuprc.com/servlet/the...ltiplex/Detail

Enjoy
Eric
So does that wooden motor mount stay together in flight and work well? Also, does it remove all the vibration?
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Old Jun 04, 2012, 06:40 AM
lownslow
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United States, FL, Cape Canaveral
Joined Nov 2011
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Quote:
Originally Posted by cynjon View Post
The MPX-recommended servos (and how the molded servo pockets are sized) is for HS-81 or HS-85 in the fuse for R/E, and HS-55 for the ailerons. However, I personally believe that the HS-55 is marginal at best with the huge ailerons. I would recommend a HS-65 or HS-65MG for those. HS-81 is adequate for the fuselage, but they're notorious for poor centering--unless you want to be chasing a changing pitch trim setting, I'd recommend the HS-85 or HS-85MG. Just my $.02--I've been very happy with my HS-65HB/HS-85 servos.
+1 great combo for this plane
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Old Jun 04, 2012, 06:48 AM
lownslow
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United States, FL, Cape Canaveral
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Quote:
Originally Posted by RCDestroyer View Post
So does that wooden motor mount stay together in flight and work well? Also, does it remove all the vibration?
When you pull the nose off a parkzone T28, P47, F4F, Extra300, you have a sturdy little motor mount attached to a huge firewall. IMO on this plane it appears both the firewall (yup there is none) and the motor mount depend in that small slice of foam across the top and bottom of the nose to provide rigidity (not gonna happen)..............peace
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Old Jun 04, 2012, 04:11 PM
The Crash King
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United States, OH, Richfield
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Quote:
Originally Posted by windrnone View Post
When you pull the nose off a parkzone T28, P47, F4F, Extra300, you have a sturdy little motor mount attached to a huge firewall. IMO on this plane it appears both the firewall (yup there is none) and the motor mount depend in that small slice of foam across the top and bottom of the nose to provide rigidity (not gonna happen)..............peace
Thanks!!!! Thats a huge help!
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Old Jun 04, 2012, 06:26 PM
Air Cooled VW mechanic
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Quote:
Originally Posted by RCDestroyer View Post
So does that wooden motor mount stay together in flight and work well? Also, does it remove all the vibration?
I added the boxed light ply (Wooden) crutch to my AcroMaster and I love it.
Zero vibrations and, yes, it stays together quite nicely even after a couple nasty landings.

Keep in mind, you still have to balance those props ;-)

Use 20 minute epoxy for the wood assembly and thick CA for attachment to the fuse. And test fit, test fit and test fit before gluing anything.

Eric
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Old Jun 04, 2012, 06:32 PM
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Also.. the PDF for the crutch is in post 2010 of this same thread.

Eric
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Old Jun 04, 2012, 06:45 PM
Bay Area Prop Buster
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If you happen upon other Multiplex threads you will hear a very common theme of nose/airframe vibration due to the poor motor mounting system. My MPX FunCub is one of them even with an after market aluminum motor mount.

Blu
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Old Jun 04, 2012, 09:35 PM
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Alberta,Canada
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Are you comparing the amp draws to the power being made by each prop?

Would you spin these props from 28-36k?

I run APC,I don't mind balancing them.
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Old Jun 04, 2012, 11:50 PM
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I have had good luck using the new "white" gorilla glue (or Sumo glue) on elapor, especially for the motor mounts. It doesn't foam too much, just enough to fill any gaps there might be and it's not as brittle as CA. Make sure you sand the contact areas and wipe down with denatured alcohol to get rid of any mold release (and that "greasy" feel) which will give you a better bond no matter what glue you use. Do the same to the plywood if you go the "crutch" route. I've flown the snot out of my AM, with the stock mount, and have never had the MOOOO...ymmv.
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Old Jun 05, 2012, 07:00 AM
lownslow
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United States, FL, Cape Canaveral
Joined Nov 2011
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Quote:
Originally Posted by Bluhammer View Post
If you happen upon other Multiplex threads you will hear a very common theme of nose/airframe vibration due to the poor motor mounting system. My MPX FunCub is one of them even with an after market aluminum motor mount.

Blu
+1 yup buddy w FunCub went to slo fly props to stop his MOO.
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Old Jun 10, 2012, 06:31 PM
Aeronaught
United States, OR, Sherwood
Joined Oct 2007
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Motor mount vibrations

I've read on the various threads about the 'hard to cure' motor mount noise and built in several of the mods as well as using the after market Aluminum mount. One thing I have found that I think is a prime cause is the mount screws not being well tightened. I've flown my Acromaster a good few times and was pleasantly suprised how QUIET it was....until this morning. I did check the mount screws before and after the (very short) flight and judged they were fine, however when I got back home ready to tear into the problem I picked up a 'real' screwdriver...not one of those dinky electronic/modeling ones and surprise-surprise...the two screws that mount the aluminum mount to the plastic bulkhead took at least two turns to snug them up. The dinky electronic size screwdriver was not up to the task....but one with a real grip showed right away that 'tight' has a couple of different versions, apparently.
Running up to full throttle was as quiet as ever, though 1/2 to 3/4 was as far as I could get before snugging up the bulkhead screws. The nose on this model has plenty of carbon cloth/pultrusions and tape CA'ed into it and seems quite solid.....the cause in this instance was definately failure to check the fastenings.

Hope this helps someone.....It's been great reading all the contributions here.
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Old Jun 19, 2012, 12:13 PM
The Crash King
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United States, OH, Richfield
Joined Mar 2010
209 Posts
I just finished my AcroMaster today!
Heres my powersystem:

FirePower 15 motor
Exceed RC 60A ESC
Exceed RC 3A BEC
Hitec HS-82MG for Elevator
Hitec HS-81 for Rudder
Emax ES08MA for Ailerons
Gens Ace 2500MAh 3s 25C
DX8 w/AR6210

I have a couple concerns. THe HS-82MG servos is always buzzing. Is that normal for that servos. To stop it from buzzing, i just move the elevator alittle bit.
Also, im having trouble getting the correct CG. It is suposed to be 110mm from the leading edge. I can only get mine 100mm.


Here is the paint scheme! Let me know what you think!
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Old Jun 19, 2012, 05:59 PM
Registered User
United States, CA, Pleasanton
Joined Apr 2002
455 Posts
Yet Anothet Turnigy Motor Question....

Hi Guys,

I was so impressed with the quality and fly-ability of my MPX Fun Cub that I have decided to build an AM.

I have a spare TR 3635-1100 that I'd like to use with the scads of 2200 - 2650 3S batteries I have on hand.

I do not intend to use the AM for 3D, but mostly as an aerobatic trainer (pattern type flying) , if you will.

The motor weight 101 grams.

So, two quick questions:

Do you think this will perform OK for my needs turning something like a 12x6 prop, and any issues with the CG given the relatively low weight of the motor.

TIA for any thoughts.

:harry
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