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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Robert Dible on October 14, 2009, 10:54:36 PM
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I'm just wondering, is a stooge required if a timer is controlling the esc?
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There are people flying electric without stooges or helpers - but it kinda creeps me out! It is a little easier on concrete because the bird can roll easier as the motor comes up to speed. However there have also been airplanes damaged becuase they got tangled in the grass as the motor was still spooling up.
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I'm glad you asked this important safety question. We all need to get the word out on this issue.
The short ans is: .... NO it is not required. BUT, we should all use a stooge or helper on every ECL flight!.
I agree with what Dennis said.
Even if we ECL flyers know that our systems are very reliable and we have our set 30 sec. of no motor run before spool up we should still use a stooge or helper when flying. It really is unsettling for the non E CL flyer to see our planes "unattended" before Take off, and it is not fair of us to make them feel ill at ease. And it also makes us "look" unsafe in our procedures, even if we think we are safe. Appearances are still important. (in CL more than most places ;-).
A few years ago, before I discovered (stumbled on it actually ;-) the sloooow spool up (and went on a compain to convince everyone to use it) we used to have our motors go from idle to full power almost instantly. This allowed easy grass starts, just like a full power up wet system.
Now that we all use the slooow spool up, which gives outstanding scale like high scoring take offs, you MUST use a stooge or helper to avoid almost a sure prop strike on grass. I let my motor spool up to about 1/2 power (depends on length of grass) before pulling the stooge string. In about 350 stooge flights on grass I have never had a prop strike.
Like Dennis said, on pavement there is not this problem. At contests with pavement, I have the helper hold it until I am holding the handle. Then I give him the signal to release (and I have told him before hand to back away from the circle on this signal) then about 15 sec later the plane starts to move all by itself for it's slow taxi and take off. This looks cool and very scale like to start the flight. :-)
IMHO: For both safety, and for appearances, we all should use a stooge or a helper, on grass AND on pavement.
Again, thanks for bringing up this important safety issue.
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>>>you MUST use a stooge or helper to avoid almost a sure prop strike on grass<<<
I use 3 second long spool up ... and I NEVER had wrong start on grass, while I remember many broken props on wet power train released from hads of helper VD~
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If you guys would use trike gear you wouldn't have to worry about prop strikes ;D
My last ship was my first trike and do believe everyone after this will also be a trike. Only thing you have to get use to is to not try to raise the nose before it has enough speed to keep the lines tight. Too early and it could very well chase you around the circle.
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It has been almost 40 years since my last circle burner. Reading about reverse rotation props to improve line tension got me reading about the subject again. Since I didn't have a stooge way back when, it alway was a problem finding a helper. I did bribe my youngest sister (5 years old at the time) into the effort for quite a while and she blames that for hearing loss all these years later. Though in full disclosure, it only seems like she can't hear men, especially her husband. ;)
Anyway, after many years of RC it's time for an "new" challenge to get reconnected. I'm sure that you have heard this many times before.
As far as safety, I am aware of what can go wrong with electronics, since I am a semi-retired Electrical Engineer. A tiny bit more electronics would resolve any concern of launch before the pilot is on the handle.
I guess the question is, would using a left hand prop make the take-off reliable without a stooge or helper?
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A LH rotation propellor allows the prop torque reaction to make the airplane roll to the right, away from the pliot (if you are flying CCW) It is a good thing.
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>>>torque reaction to make the airplane roll to the right<<<
and just opposite in reverse flight :-)
I think the only place where the pusher prop helps is hourglass (second and third corner) and vertical eight - the precession helps to pint the nose out instead of in.
That is all nice, but how you guys want solve all other issues of precession and P factor. Our models are asymetric to conterballance those forces, if you change the rotation, you have to change whole layout of stunter.
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Hi All,
It's not the roll, it's the spiral airflow induced yaw, which is now outboard with a left-hand prop.
Asymmetry? That's why the first thing Hunt and I discussed was a couter-rotating twin. The pusher prop works so well that we may not bother.
later,
Dean
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:-)
does not matter if it is reaction roll or induced yaw, both needs to be ballanced by either flaps or rudder ... so where is the difference? VD~
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sorry not flaps AND rudder
flaps AND rudder ... I think if I change the rotation, I need to to change both to puth the model to previouse position ... at least that is what I had to do when I tested pusher prop
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A LH rotation propellor allows the prop torque reaction to make the airplane roll to the right
I assumed by this, Dennis meant that the airplane would turn right away from the pilot and thus keep the lines tight on takeoff.
The reaction in the air during turns is "above my pay grade".
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Rob
Just when the airplane is accelerating to flight speed it can be at risk (too strong a word really) to torque. Rolling in (outboard wing up) can ruin your whole day, rolling out (o/b wing down) Is a lot easier to deal with.
Normally with IC with a launch helper or a stooge the engine is running full speed at launch and the airplane quickly gets to flying speed - and airspeed usually masks the torque effect. We've been launching our electrics while the motor is still spooling up (see Rudy's post above) so it comes up to speed slower and is also exposed to torque effects - you can see the o'b wing riding high on take-off.
Of course once you get airborne then you can start doing tricks on PURPOSE!
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Dennis - IC engine at full power staying on ground has much higher torque that slowly spooling prop :-) ... I never had any trouble on take off with slowly accelerating electric, but I remember many with IC engine :-)
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I think the real issue, having it actually happen to me, is that when the plane starts rolling slowly, it is prone to any field imperfection which can easily turn it in towards you or bump the nose down and cause a prop strike :'(. So yes you need to be careful about the spool ups being too slow. Thats why I have my ESC set to spool up as fast as possible.
To stooge or not to stooge, the question depends on the field condition. If we just cut it and it is nice and smooth, then maybe I'll risk it. If it needs cutting, then I'll use the stooge.
I have flown plenty of IC planes (the Fox 35 powered Skyray tests last week for example) with one main wheel. Here the torque rolls the inboard wing into the ground making it easy for the leadouts to snag --now that is scary at any power setting! So even with a stooge (or a launcher) I am backing up pretty fast with my hand held up high to try and keep the leadouts above snag level.
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Dennis - IC engine at full power staying on ground has much higher torque that slowly spooling prop :-) ... I never had any trouble on take off with slowly accelerating electric, but I remember many with IC engine :-)
Of course, but thrust is also much higher and accel to flight speed is very fast - torque reaction very short lived. EXCEPT I remember some Rat Racers that did some beautiful rolls on takeoff, the worst actually did about 3/4 of a roll before.... :X