Scale MD 500 E, 450 class

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bassslayer1960

Member
Good day to all,
I too,have a MD 500 News version that I aquirred use
I have been into heli's now for about 3.5 years.
Where did you find the info on rotor phasing of rc helis?
The Trex450pro that mine is built around has the 7210 also.
For power I am using Scorpion 1880kv on 6s, 121MG,11T Pin.
After I meticulously setup the head,+/- 10 deg pitch and 8deg cyclic pitch, the mechanics work perfectly to ~3 degrees + pitch,then stall out.
Nothing is binding or dragging .
The only way she will lift off, is to feather in some elevator.
This caused several crashes.
I have shelved this bird and moved onto another project, but would love to get her finished soon.
Any help in solving this problem would be greatly appreciated!
 
D.O.G.

D.O.G.

Goblin 380 Supporter
I'm not to sure but I think you need to have 6 degrees cyclic pitch instead of 8 degrees.
 
Boogs

Boogs

Member
D.O.G. said:
I'm not to sure but I think you need to have 6 degrees cyclic pitch instead of 8 degrees.
Click to expand...

Ivan is correct, you start out setting, or teaching the 7210 6 deg first, (step j) be sure to get the blue light before moving on to setting (step k) the amount of + - pitch you're after at set , Is that the 10 degrees you mentioned? You'll want a blue light for neg. pitch and a red for positive.
Of course you must be at 0 deg. mid stick before moving to the other settings.

Are you timing a four or five blade head? This link is for the 5 blade..https://www.youtube.com/watch?v=Apx9phI5Sek

Hope this helps.
https://www.youtube.com/watch?v=Apx9phI5Sek
 
B

bassslayer1960

Member
I thank you all for the help, but the 8deg cyclic was a typo.
I meant to say 6deg, just as the software describes.
I am leaning towards a phasing problem, but haven't had time to check it out yet.
The head is a 4 blade.
 
Boogs

Boogs

Member
Glad to help bassslayer. Out of time with the phasing will give very bad flight characteristics for sure.
 
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bassslayer1960

Member
Well I finally made time to do a once over of my head setup.
It was indeed out of phase.
After resetting the head in phase , and doing a bottom to top adjust, she still will NOT lift off!
I am using +/- 10 deg. collective and 6 deg. cyclic.
My pitch and throttle curves, are both linear.
Any help in solving this problem will be GREATLY appreciated.
I have read and watched all the info I can find on this problem.
HELLLLLLPPPP!!!!
 
Tony

Tony

Staff member
Try bumping it up to about 12.5º on the collective pitch and see what that does. Also, try running in an 85% flat throttle curve. It may need more head speed. Remember, with 4 blades you have double the resistance on the head so the motor has to work twice as hard to keep it going. This is theoretical, but still, there is more drag and more drag means a slower head at the same percentage.
 
Boogs

Boogs

Member
Tony said:
Try bumping it up to about 12.5º on the collective pitch and see what that does. Also, try running in an 85% flat throttle curve. It may need more head speed. Remember, with 4 blades you have double the resistance on the head so the motor has to work twice as hard to keep it going. This is theoretical, but still, there is more drag and more drag means a slower head at the same percentage.
Click to expand...
All of what Tony said, and maybe go up a tooth on the pinion gear.
 
Tony

Tony

Staff member
If there is more drag, you would actually want to go down a tooth so that the motor is not working as hard. I know what you are thinking though, add a tooth for higher head speed. But doing so will introduce more heat into the motor.
 
B

bassslayer1960

Member
Good day to all,
Today I raised the pitch to ~12.5 +/- collective first.
Then tested with the same results.
After I gave her an 85% throttle curve, it almost lifted off at full positive pitch.
Next I went with a 100% throttle curve with same results. (WTFFFFFFF!)
I lowered the throttle curve back to 85% and feathered in some up elevator, she took of like a rocket straight up!!!!!
I had no control of the collective or cyclic.
I engaged throttle hold, and autorotated back to terra firma.
Upon inspection, I noticed the swashplate was canted.
Two of the 3, Corona 919MG servos had a stripped PLASTIC gear inside.
So much for being MG, I will NOT be using them again.
My theory is the servos not having enough torque to drive the head under a load.
Does anyone else have an opinion?
Now I am waiting for the Align DS450M set to arrive.
By the way, the temp of the motor is 147F.
 
holtneil

holtneil

Active Member
4 bladed and above will be ok on a metal gear servo plastic never lasts long as it does have more loading on the head and swash , you also need to run a slower head speed as the following blade will hit dirty air from the leading blade , on the Trex 500 4 bladed head align does say drop a tooth on the pinion , a good governor also helps with collective loading
 
Tony

Tony

Staff member
Ah, the good ole corona servos. I have 3 of them and they are there only to remind me to never purchase them again lol. I didn't have the issue you are having (mine are metal gear), but the centering is just absolutely HORRIBLE on those servos. The Align's will do you just fine, but if I had gotten to this sooner, I would have suggested the ALZRC servos that I'm running. They are fantastic! And there are some other servos that are even cheaper that I used in my SE V2 that are great for the price at only $8 a piece.

Might want to go ahead and lower your pitch back down to 10 now that you have figured out the servos are just not powerful enough. They will be with Align, that's for sure.

Keep us posted.
 
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bassslayer1960

Member
Hey Tony,
Thanks for the input, but you didn't mention the part# for the ALZRC servos that you are using.
I should have my DS450M's, by mid week.
I'll keep everyone posted on my progress
By the way, I will NO LONGER be sparing the expense, when it comes to my toys!!!!!
Thanks again, Robert
 
Tony

Tony

Staff member
That is one of the hardest things to learn when it comes to these helicopters. Learning to get quality equipment and electronics, especially for the tail. I as well started out on the cheap, and every single time it bit me in the butt. And the reason I didn't put the link is because you ordered the Align servos. But below is the link to those just in case you want a backup set. I now have two sets of cyclic servos of these and so far, so good. Although I have not done much other than setup.

ALZRC Devil 380 420 480 Parts DS452MG 450 CCPM Mini Digital Metal Servo
 
Tony

Tony

Staff member
I don't. Time has not been on my side and all of my projects have been put on hold for a while.
 
B

bassslayer1960

Member
Very good Tony,
I got my DS450M's yesterday and I'm in the process of installing and doing another bottom to top adjust as we speak.
I'll keep everyone posted.
Robert
 
Tony

Tony

Staff member
Awesome! Let me know what you think of those servos. I have never run the 450's, all I have run is the 410's.
 
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