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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Bob Reeves on October 20, 2014, 03:29:51 PM
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Brett made a statement in the general section that the electric guys are moving away from Reverse Rotation I would like to know more details as to the reasons for this trend. I have been flying a reverse rotation 4 stroke for a few years and like everything about it. What am I missing?
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Brett made a statement in the general section that the electric guys are moving away from Reverse Rotation I would like to know more details as to the reasons for this trend. I have been flying a reverse rotation 4 stroke for a few years and like everything about it. What am I missing?
You beat me to it Bob. I'm interested too.
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4 planes that I tried with tractor and pusher props all liked the pusher prop.This years build is going to be designed with a pusher up front.
Bob
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I'm also very interested in hearing the reason why. Everything we have ever tested with ECL power seems to work better with reverse rotation.
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Only thing that comes to mind is prop selection. However the pusher prop choices is quite large.
n~
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Brett made a statement in the general section that the electric guys are moving away from Reverse Rotation I would like to know more details as to the reasons for this trend. I have been flying a reverse rotation 4 stroke for a few years and like everything about it. What am I missing?
Igor Burger mentioned it in a few post..
http://stunthanger.com/smf/index.php/topic,35516.0.html (http://stunthanger.com/smf/index.php/topic,35516.0.html)
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From what I understand some planes like tractor some like pusher you just have to try it both ways.
MM
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Only thing that comes to mind is prop selection. However the pusher prop choices is quite large.
I know that Paul Walker recommended it to Mike Haverly on one of his profiles, for reasons of trim. So it's not just a prop choice thing.
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I plan to try a standard prop on my new electric. The reverse rotation props I'm using pull my arm off.
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Not an engineer, but fortunate to fly with several very knowledgeable types...and I'll toss in a bit of personal observation, so here goes.Seems that the pusher provides a welcome margin of control in that the aircraft will -upon loss of line tension created by one's own wake , turbulence or a wind gust, fly back out; allowing the aircraft to regain line tension in time (hopefully) before disaster strikes .Key is the air spiral created by the pusher around the rudder/vertical fin .
Tractors don't offer a similar outcome . As one would expect, they have the opposite effect upon the air spiral around the rudder/vertical fin, so one is left having to add rudder and/or motor offset ( control-line 101). Plenty of line tension, but not the quite the same...
I know of an electric flyer who flies clockwise and has benefitted from switching back to tractor. Can't say that is a general rule; just worked better for his particular aircraft.
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Last year's airplane flew OK with a backwards (negative rotation about the airplane X axis) prop. This year's didn't. The most awful thing it did was a perverted lomcevak at the top of the hourglass. Switching to a normal (positive rotation about the X axis) prop made it OK. Could be that our airplanes were initially optimized for positive-rotation props, and we haven't yet figured out motor orientation, vertical tail position, and stuff like that for backwards props. One cool thing is that you can get matched pairs of quadrotor props cheap and try both ways.
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i tried counter clockwise props on two of my elecs and both gave me trouble in the HR glass switched back to clockwise and problem went away
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i tried counter clockwise props on two of my elecs and both gave me trouble in the HR glass switched back to clockwise and problem went away
Clockwise and counter clockwise looking from the front or from the back?
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In flight ground school, they told me that prop rotation was from the viewpoint of a pilot, sitting in the cockpit.
Floyd
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And referred to as "Right Hand" or "Left Hand" when they're on the front, pulling the plane. They are NOT "pusher" props when pulling the airplane. n1 Steve
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Think of starting an engine from in front of the plane. Would you use your right or left hand fo the best flip?
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I plan to try a standard prop on my new electric. The reverse rotation props I'm using pull my arm off.
And that's it right there, my Vector 40 with a 12-6P pulls like a truck on lines, switched to a standard and it's much better now. I'm thinking others are doing the same.
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Interesting comments on the hourglass and completely different from my experience. The two stunt ships I changed to reverse rotation (Left hand rotation from the cockpit) showed a significant improvement in line tension at the top of the hourglass and vertical eight. No detectable loss of control or line tension on insides just improvements on outsides. I didn't change the normal 2deg of engine right thrust I always put in and do not have any engine down thrust in either airplane. The ships were re-trimmed to turn flat with a small tip weight and leadout position tweak but even before the re-trim I noticed the improvement in hard outsides.
Wished I could put a reverse crank in the ST 51 in my Skylark, it has always had issues with outside line tension. I've managed to trim most of it out but have no doubts a reverse rotating engine would fix it.
I also don't get the two comments on line tension, overall line tension can be trimmed somewhat with leadout position and tip weight but it really depends on the airplane's speed and weight which doesn't (or shouldn't) magically change just because you are turning the prop the other direction.
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Guys, if you change prop, you must completaly RETRIM model, so simple exchange only shows for which prop is model trimmed. If model pulls somewhere and somewhere not, it is simply not trimmed (or even designed) properly :- ))
As I wrote already in that other thread, I did not get as good trim with pusher as I got with tractor prop, also several other guys reported the same. However it is true for classic models type like my Maxes. I can imagine that inliners will not show such differecnece or al least no so visibly. However in any case, the trick is and always will be prop with low presession :- ))) the larger is not always the better :- ))