26 replies to this topic

[Windbreaker]

CrispyCargo, on 01 February 2012 - 08:57 PM, said:

I was using 12mm CF booms on my hex with a similar MTM size as yours, and there were vibrations like CRAZY. When I switched to larger (size 500) aluminum booms, the vibrations went away.

I wonder if that's because carbon fiber is really stiff and transmits the energy efficiently or because they resonate readily?

[Windbreaker]

For motors and props, you could try what I did.

-- estimate what the total weight would be.
-- use the motor/prop data at Innov8tive Solutions to determine what combination would be the most efficient.

I chose Cobra motors and APC props because that's the only information I could find. Otherwise it would have been total guesswork.

Even with a spreadsheet, it's somewhat of a chicken-egg chase. The total weight depends upon which motors you use. And the motors you use depends on how much the quad weighs.

Another possibility is using eCalc to figure it out, but you'd have to enter individual motor/prop combinations one at a time, then sort out the results.

Something else to consider: Right before I switched to a quad, I was reading about how some people changed their 3s helicopters to 6s and found a significant improvement in efficiency. For a given amount of watts you draw fewer amps. That meant that everything ran cooler and the battery wires weren't being pushed to the limit.

This becomes another factor in finding the right motor as there aren't as many that operate at lower RPMs at 22 volts.

When I searched for motors, my first criteria was voltage. Then I started looking for combinations that provided the necessary thrust, lowest amperage draw, etc.

[actionplus]

I use the same arms on my tricopter.
But its not as big as yours. I cut it, so it about 500mm. Maybe I will switch it to a quad or a hex, now that I see your frame.

[johnnycat500]

actionplus, on 02 February 2012 - 02:50 PM, said:

I use the same arms on my tricopter.
But its not as big as yours. I cut it, so it about 500mm. Maybe I will switch it to a quad or a hex, now that I see your frame.

Do you have any flexing problems with yours?

[actionplus]

Nope. It's the most stable one I have. But again. I am only 500mm. Yours is going to be 800.

[CrispyCargo]

Another point is that my Hex was using the 500 booms, so my MTM distance was 1000mm. That could have added to the increased vibrations, but you are using aluminum, so i'm sure it will be plenty strong and rigid.

[johnnycat500]

I ordered motors and esc's and should get them tues. I have coming Cobra 2814-20 motors and Next level 40a esc's. I also have one landing gear done with 6 LED's on each side.I bought trex 500 booms and AGL Hobbies boom blocks. This frame with the 500 booms is 1000mm. I will make another frame with mounting holes for both 450 and 500 boom block holes. I am going to run 2 - 2200 4cell in parallel. The sad part is I don't have an OP board for it.   :-{

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