pic R/C roto hovers 2" off ground

kellyo

kellyo

Pre-takeoff checklist
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kello
http://images.google.com/imgres?img...?q=aviation&start=280&svnum=10&hl=en&lr=&sa=N

helicopter3.jpg
 
i've never really studying rotocraft at all, not even sure how the aerodynamics work...regardless, this is pretty skillful
 
Unless they can reverse thrust, I don't see how this is anything but a photo titled "1 millisecond before the crash" ... am I wrong?
 
gkainz said:
Unless they can reverse thrust, I don't see how this is anything but a photo titled "1 millisecond before the crash" ... am I wrong?
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They've got to have fully feathering rotors to do that.
Wonder why they don't do it in full size choppers, that would be a kick.
 
gkainz said:
Unless they can reverse thrust, I don't see how this is anything but a photo titled "1 millisecond before the crash" ... am I wrong?
Click to expand...

Unlike full sized helicopters, scale models have the ability to fly with negative G's and thus can be flown inverted by a skillful "pilot". Right side up ain't easy and I suspect that "mowing the grass" requires serious skill.
 
lancefisher said:
Unlike full sized helicopters, scale models have the ability to fly with negative G's and thus can be flown inverted by a skillful "pilot". Right side up ain't easy and I suspect that "mowing the grass" requires serious skill.
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That's it, Lance. The real thing depends on gravity to keep the fusilage aligned properly with the rotor system. It may be that the models can't go fast enough to require blade flapping (I don't know that for a fact) and thus might be able to have a totally rigid Inon flapping) rotor blade system.

I recall reading somewhere about an aerobatic helicopter which had a rigid rotor system (the blades flap by flexing rather than through flapping hinges), but I don't know that it could be flown inverted. I doubt it though, because the collective would need to be able to reverse pitch. Which would certainly make autorotations interesting...
 
Dave Krall CFII said:
They've got to have fully feathering rotors to do that.
Wonder why they don't do it in full size choppers, that would be a kick.
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:hairraise: Holy Schnikes!! Thats crazy talk!! :yes: :eek:

I'd watch you do it though. :D
 
hey guys...that IS skill.

Piloted by Alan Szabo...cant remember if it was Jr. or Sr.

check this one out: http://www.helihobby.com/videos/SuperHeadLong.wmv

They've been flyin RC helis FOREVER!!! and they're still in thier teens if im not mistaken.

And yes, RC helis have both positive and negative Pitch...so inverted hovers are possible. You should try downloading some Heli competition's online...they're impressive to say the least. To think these guys are controlling all those movements with their fingers; hundreds of feet away (both below and aside) is AMAZING. Im still tryin to perfect smooth aerobatics with my helis, but its a treat to see the pros doing it.
 
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Dave Krall CFII said:
They've got to have fully feathering rotors to do that.
Wonder why they don't do it in full size choppers, that would be a kick.
Click to expand...

Well, um... you try first... :)
 
AirBaker said:
Well, um... you try first... :)
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OK, got a chopper with negative main rotor pitch for me ?

BTW: One of my private students was an RC "pilot" and he got his skills down for the PPL faster than anyone I've seen. Of course cost wise, it cost him more to learn on the RCs but he was just doing that for fun anyway.
 
Dave Krall CFII said:
Of course cost wise, it cost him more to learn on the RCs but he was just doing that for fun anyway.
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The American way!
 
kellyo said:
The American way!
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Indeed, or he had no medical.

The other highly significant factor that allows such maneuverability with these RC choppers is a nice and high thrust to weight ratio due largely to the fact of their lowpayload consisting only of very short range fuel and no pilot weight to speak of. That high thrust to weight ratio is the main reason that even with full feathering rotor, it would not be doable in say, an R22.

The upsidedown hover is actually more stable the closer to the ground it is performed due to the CG being essentially in the upper portion of an aerial, conoid force field of rotor wash spreading out below it while in ground effect. To start practicing the maneuver, the operator simply holds the RC chopper upside down until proficiency is attained enough to let it go. I have seen film of that maneuver done out of ground effect too.
 
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