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Model Forum / Radio Controlled / Helicopters / July 2007Trouble trying to hover
I have a Trex 450 SA. As the heli leaves the ground the head stays pointing in one direction and it stays level. The heli goes left, stays level and pointing straaight. Just like straffing in a video game. No yaw, no roll, not pitch - just left. Eventually the heli makes a circle. I can't figure out how to correct this. I have a gyro but not a heading lock. Thanks Doug > I have a Trex 450 SA. > [quoted text clipped - 14 lines] > > Doug right trim I should imagine, if you're looking at the skids and trying to trim all helicopters even full size hover with one skid lower than the other >> I have a Trex 450 SA. >> [quoted text clipped - 18 lines] > trim all helicopters even full size hover with one skid lower than the > other Absolutely! The tail rotor is producing a thrust to the left as it counters the torque reaction from the main rotor. If the main rotor is perfectly level, there will be no counter force to prevent the model from moving in the direction of the tail rotor thrust. The 1:1 scale pilots call this "translating tendancy." >>> I have a Trex 450 SA. >>> [quoted text clipped - 23 lines] > the direction of the tail rotor thrust. The 1:1 scale pilots call this > "translating tendancy." ah I knew they did but was unsure why, makes perfect sense now >>>> I have a Trex 450 SA. >>>> [quoted text clipped - 24 lines] >> call this "translating tendancy." > ah I knew they did but was unsure why, makes perfect sense now Yup! :-) Clockwise rotor rotation will always tilt slightly to the right. Counterclockwise rotation will tilt slightly to the left in a stable hover. It all has to do with which way the tail rotor is blowing! ;-) On the 1:1 scale pilots, you have to be carefull about refering to rotor direction as clockwise or counterclockwise. I got my arse hopped about that by one of them once. From their point of view (sitting in the bird), what we call a clockwise rotation is a "left to right" rotation because the rotor blades come into view from their left and move right. Our counterclockwise rotation will do the opposite. It's not a big deal one way or the other, just a bit of trivia info that I've come across through the years. Fly Safe, Steve R. >>> Absolutely! The tail rotor is producing a thrust to the left as it >>> counters the torque reaction from the main rotor. If the main rotor is >>> perfectly level, there will be no counter force to prevent the model from >>> moving in the direction of the tail rotor thrust. The 1:1 scale pilots >>> call this "translating tendancy." So do we model pilots. :) (Oh wait, I do both, so, um.. yeah!) >On the 1:1 scale pilots, you have to be carefull about refering to rotor >direction as clockwise or counterclockwise. I got my arse hopped about that [quoted text clipped - 3 lines] >rotation will do the opposite. It's not a big deal one way or the other, >just a bit of trivia info that I've come across through the years. What tight-assed chopper driver gave you crap for that? I've never used the term "right to left" or "left to right" in any of my hangar BS sessions (or in all of my studies) I've always used clockwise and counter-clockwise (or anti-clockwise when speaking to Eurocopter pilots) >>>> Absolutely! The tail rotor is producing a thrust to the left as it >>>> counters the torque reaction from the main rotor. If the main rotor is [quoted text clipped - 4 lines] > > So do we model pilots. :) (Oh wait, I do both, so, um.. yeah!) I only brought it up because most RC pilots I've met have never heard the term before. >>On the 1:1 scale pilots, you have to be carefull about refering to rotor >>direction as clockwise or counterclockwise. I got my arse hopped about [quoted text clipped - 12 lines] > counter-clockwise (or anti-clockwise when speaking to Eurocopter > pilots) It was a long time ago. I don't remember where or when I met the guy but we were talking helicopters in general and I, of course, was speaking from the RC pilots point of view and I remember mentioning something about the rotor system on my model turning clockwise. His response was something like, "What? Where do you get that from?" I explained that it was the direction the rotor system appeared to be turning when viewed from above, like when it's on the ground and we're spooling up for take-off. He responded that my point was irrelevant for "him" because from his point of view, he's not looking at it from that perspective. I don't think he was trying to be a horses arse about it but he was "very" matter of fact about it, almost to the point of being terse. I remember thinking, "yeah, right, Ok guy, whatever you say," but I didn't argue the point. It's just something that I've always remembered and it has altered the way I talk to 1:1 scale pilots when I've had the chance. I've never had a problem with any others I've talked to. There are a few of things that I've always found interesting, sometimes scary, when talking to 1:1 scale pilots. 1. I've always been surprised by the number of them I've met that didn't even know that the RC versions exist. 2. Of those that knew that RC model helicopters exist, it's amazing how little they know about their capabilities. As an example, a friend of mine just got back from a vacation in Florida and he had the opportunity to spend a significant amount of time with some local military heli pilots and he said that several of them were convinced that he was totally BSing them when he was talking about our models aerobatic capabilities. A couple of them were convinced that there was no way a helicopter, "any" helicopter, could fly in a sustained inverted mode. 3. While I'm no expert in rotorcraft dynamics, I have done a lot of reading through the years and I think I've got a pretty good grasp of how helicopters fly and why things like translational lift, settling with power (aka, vortex ring state), translating tendency, etc., occur. I've met a number of 1:1 scale pilots that didn't exactly give me the impression that they were on top of it with regards to such things. I could be wrong about that. :-) Fly Safe, Steve R. >I only brought it up because most RC pilots I've met have never heard the >term before. Yep. I'm amazed how bass-ackwards a lot of RC heli pilots are when it comes to the aerodynamics of the models. I've literally had people physically threaten me over things like THEIR perception of ground effect when I've tried to explain and educate them. >It was a long time ago. I don't remember where or when I met the guy but we >were talking helicopters in general and I, of course, was speaking from the [quoted text clipped - 11 lines] >when I've had the chance. I've never had a problem with any others I've >talked to. Damned heli pilots.. All ego. :) >There are a few of things that I've always found interesting, sometimes >scary, when talking to 1:1 scale pilots. > >1. I've always been surprised by the number of them I've met that didn't >even know that the RC versions exist. Too much Jet-A fumes or something.. Hey.. Av-Gas *IS* leaded.. :) >2. Of those that knew that RC model helicopters exist, it's amazing how >little they know about their capabilities. As an example, a friend of mine [quoted text clipped - 4 lines] >were convinced that there was no way a helicopter, "any" helicopter, could >fly in a sustained inverted mode. Sounds like a good opportunity for making some money with "bar bets" >3. While I'm no expert in rotorcraft dynamics, I have done a lot of reading >through the years and I think I've got a pretty good grasp of how [quoted text clipped - 3 lines] >they were on top of it with regards to such things. I could be wrong about >that. :-) I've met a few CFI-H's who didn't have a grasp of the basics and a few that knew their stuff, but couldn't explain it well enough to teach anyone. >>3. While I'm no expert in rotorcraft dynamics, I have done a lot of >>reading [quoted text clipped - 10 lines] > that knew their stuff, but couldn't explain it well enough to teach > anyone. And that's what blows me away. I can't understand how a person earns a CFI rating "without" having at least a basic grasp of such fundamentals. It's not "that" complicated when you get down to it and personally, I firmly believe that knowing what's happening to the rotor system helps when it comes time to control it. >And that's what blows me away. I can't understand how a person earns a CFI >rating "without" having at least a basic grasp of such fundamentals. It's >not "that" complicated when you get down to it and personally, I firmly >believe that knowing what's happening to the rotor system helps when it >comes time to control it. This is part of the reason I've "stalled" my full scale training. I can't find an instrument instructor worth a damn. They're either tattooed and pierced kids who have the cert, but no experience, or experienced but can't teach 'cuz they've forgotten the basics. >>And that's what blows me away. I can't understand how a person earns a >>CFI [quoted text clipped - 7 lines] > tattooed and pierced kids who have the cert, but no experience, or > experienced but can't teach 'cuz they've forgotten the basics. On the latter group, maybe you could trade some time with them. You teach them the aerodynamics and they get you through the IFR proceedures! :-) Thanks for the info. got stuck in the grass, thought it was a rocket then a rock. Parts on order. >>>>> I have a Trex 450 SA. >>>>> [quoted text clipped - 39 lines] >Fly Safe, >Steve R. Thanks for the info. got stuck in the grass, thought it was a rocket then a rock. Parts on order. >>>> I have a Trex 450 SA. >>>> [quoted text clipped - 25 lines] >> >ah I knew they did but was unsure why, makes perfect sense now Thanks for the info. got stuck in the grass, thought it was a rocket then a rock. Parts on order. >>> I have a Trex 450 SA. >>> [quoted text clipped - 24 lines] >the direction of the tail rotor thrust. The 1:1 scale pilots call this >"translating tendancy." Thanks for the info. got stuck in the grass, thought it was a rocket then a rock. Parts on order. >> I have a Trex 450 SA. >> [quoted text clipped - 17 lines] >to trim all helicopters even full size hover with one skid lower than >the other How about trying the radio?? >I have a Trex 450 SA. > [quoted text clipped - 14 lines] > >Doug |
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