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Old Nov 23, 2014, 01:49 AM
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Pakistan, Punjab, Lahore
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Engine Mounting Orientation For Multicopter

I am attempting to build an engine powered Quad-copter and I wanted to ask if I mounted a DLE engine in such a way that the axis of propeller thrust was exactly opposite to the direction of gravity (refer to picture), would the engine work fine or would there be problems waiting for me ?
I intend to run my engine most of the time at 60-80% throttle.


Plus the quadcopter can rotate along x and y axis upto +/-30 degrees, would this imply any further precautions to fuel tank mounting than the conventional way in an RC plane ?
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Old Nov 23, 2014, 07:16 AM
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With the two stroke engines we use, the engine orientation is pretty much anything you want to use. About the only thing to complicated it, is that in some orientations it may be harder to prime the engine to get it to start. But other than that, the engine orientation is anything you want to use. It will not hurt the engine any. The engine doesn't care.

Interesting project. Do let us know how it goes and post some pics too.
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Old Nov 23, 2014, 11:33 AM
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Earl I'm all for helping a fellow modeler, However with the FAA busy looking at all our activities while figuring out how to regulate the masses of drones I have been cautious and a bit skeptical when I see a post like this. We see an individual that has only one post, does not identify his location, does not state why he wants to build such a large vehicle. IMO it would be safer to stay away from this one until the OP provides more information.
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Old Nov 24, 2014, 07:27 AM
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Quote:
Originally Posted by earlwb View Post
With the two stroke engines we use, the engine orientation is pretty much anything you want to use. About the only thing to complicated it, is that in some orientations it may be harder to prime the engine to get it to start. But other than that, the engine orientation is anything you want to use. It will not hurt the engine any. The engine doesn't care.

Interesting project. Do let us know how it goes and post some pics too.
Thanks a lot for clearing that out.
I am currently at initial stages. I have assessed around 7-8 possible hybrid configurations and dumped about 3 CAD designs but haven't started practical work yet.
Will surely post some pics once it gets practical.
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Old Nov 24, 2014, 12:25 PM
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There have been several people that built hybrid multirotor aircraft. Some of them were using them to spray the farm crops. et cetera. So it is doable.

First application of hybrid multirotor . (2 min 40 sec)
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Old Nov 27, 2014, 12:32 PM
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Yup .. it is definitely doable ... I am trying to employ a different technique..
I've attached a basic sketch of the concept
The general idea is to try and maintain equal rpms of the both engines using digital tachometers and PID control. Any slight differences in torques due to fluctuations in Engine RPMs will be overcome by the electric motors and flight control unit. This way the space in the center can be used for a payload that won't experience direct air turbulence.

The only challenge I can't seem to solve is ... where to get hold of a near identical counter rotating Engine.
The engine I selected is DLE 55 and I 've searched extensively throughout this forum to find someone who has successively reversed this engine ... but none did I find.
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Old Nov 27, 2014, 06:49 PM
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Quote:
Originally Posted by mjerrar View Post

The only challenge I can't seem to solve is ... where to get hold of a near identical counter rotating Engine.
The engine I selected is DLE 55 and I 've searched extensively throughout this forum to find someone who has successively reversed this engine ... but none did I find.
Very few people need to reverse the engine direction so you wouldn't find much about it.

I don't know what the ignition timing is on the DLE 55. Lets say it is 30 degrees Before Top Dead Center. You would move the magnet and hall sensor to 30 degrees after top dead center, that way when you turn the engine in the reverse direction the ignition is now 30 degrees BTDC.
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Old Nov 27, 2014, 07:00 PM
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Yes like 600Bob stated, you only need to move the timing sensor, so it is on the opposite side. Then you can run the engine in reverse. You normally don't need to move the magnet. Just position the hall effect timing sensor so it is 30 degrees after Top Dead Center, which is them 30 degrees Before Top Dead center when you run the engine in reverse.
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Old Nov 27, 2014, 08:07 PM
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Yeah, I guess the magnet would be inline with the crank pin so just move the hall sensor. Guess I was over thinking it LOL.
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Old Nov 27, 2014, 08:43 PM
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Ummmm..., don't those ignitions have a built in advance/retard??
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Old Nov 27, 2014, 09:53 PM
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Ummmm..., don't those ignitions have a built in advance/retard??
I think most have some amount of variable timing built in. So?????????
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Old Nov 27, 2014, 10:08 PM
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Yeah, I guess the advance/retard curve (whatever it is) would be the same, regardless of rotation.
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Old Nov 27, 2014, 10:13 PM
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So an engine running in the opposite direction is going to be advancing/retarding opposite the direction it needs to?
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Old Nov 27, 2014, 10:26 PM
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So an engine running in the opposite direction is going to be advancing/retarding opposite the direction it needs to?
The ignition doesn't know which way the crank is turning, The timing is determined by engine RPM.
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Old Nov 28, 2014, 08:07 AM
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Agreed. It's going to do the same thing, but, now that we have an engine turning in the opposite direction, isn't the advance/retard still going to move the same way it did originally?

Maybe too much turkey yesterday. Struggling to get my head wrapped around this...
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