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Model Forum / Radio Controlled / Helicopters / October 2007tail problems after Raptor 30 V2 electric conversion
Hi, I have a RAPTOR 30 V2 which I recently converted to electric (using the TPPACKs conversion kit.) You may assume that this heli has flown for 3 years like a dream as a gasser. The conversion kit also came with a new MAIN GEAR (111 tooth, versus the orginal 95 tooth) but now all of a sudden the heli wants to spin around as the throttle comes up. I have the rudder over HARD and the tail still wants to spin around; albeit slowly ;<>) All other aspects of the Raptor are all original/stock... main blades, tail blades, tail drive/belt/gear, etc... I assume that with the new larger main gear there is a new ratio between MAIN and TAIL, but I can't seem to compensate using just the tail blades offset since they are already at the "stops" and can't go any further ! I must assume that with a larger MAIN GEAR that I now need a larger belt gear underneath.... OR maybe there is something else I'm missing here??? I am considering just putting the original MAIN GEAR back on ... any suggestions??? thanks, tob > Hi, > [quoted text clipped - 21 lines] > I am considering just putting the original MAIN GEAR back on ... any > suggestions??? Longer and wider tail blades would be the easiest first step to take and if that doesn't work make a calculation to see IF the tails are turning at a different ratio to the original. I can't see TT making THAT much of a f.ck up, but nothing surprises me anymore and it's a simple job to work out the ratios.  SignatureBeav VN 750 Zed 1000 OMF# 19 > <t...@sourcecode-inc.com> wrote in message > [quoted text clipped - 39 lines] > Zed 1000 > OMF# 19 Thanks, Beav... I actually did try the old, original MAIN GEAR, but (silly me) it hasn't got a snow-ball's chance to work since its WAY TOO small a circle (and the brushless motor and mount can't be "pushed in" any farther... ) so the new larger MAIN GEAR must be used. I think overall larger blades on the tail is the simplest thing to try.... But here's a thought (and I know you've flown everything that has swings a prop so perhaps this will make sense to you?) What about taking some of the pitch OUT of the main blades that way they grab "less air" (and I am hoping) therefore "pushing" the frame underneath less rigorously than they do now?? And thanks for taking a stab at this! tob >> <t...@sourcecode-inc.com> wrote in message >> [quoted text clipped - 52 lines] > > tob The size of the maingear should have nothing to do with the speed of the tailblades. The size of the maingear and the pinion gear determines the gear ratio. 9 something for 30 size, 8 something for the 50. Whatever for the electric as it depends on the Kv (RPM/V) of the electric motor. The rpm of the maingear -and therefore the tail- should be the same between the 50 and the electric version since that determines the headspeed. You need to check the headspeed. Around 1800 rpm is good for a 50. If it is too low either increase the throttle curve, increase the battery voltage or change the pinion gear size. Fritz > t...@sourcecode-inc.com wrote: > >> <t...@sourcecode-inc.com> wrote in message [quoted text clipped - 66 lines] > > Fritz At the moment I do not recall the specs of the motor (I'm away from home) but I think your idea regarding headspeed is in the same vein of my thought to The Beav regarding pitch... it boils down to a notion of the main blades currently imparting (more) rotation to the frame than I had when the V2 was a gasser; and so the tail rotational speed is not adequate anymore to keep up with the rotational torque. In 10 years of flying helis I can honestly say that I never had to "worry" about headspeed before (and so never purchased even so much as an RPM meter!) the kits all came out of the box, went together, and flew wonderfully ... I guess I'm paying for that now. That being said, perhaps I could ask for a little more education regarding headspeed. I'm guessing that since the tail can not even keep up when the heli is BELOW hover that means the throttle curve is already "too high". If I were to change the throttle curve to lessen the headspeed in the area below and up to the "hover point" on the stick, doesn't that just "move" the problem up into the higher end (i.e at higher throttle?) Unless you mean for me to take the ENTIRE CURVE down (i.e. all 5- points get moved to lower throttle point. And if this is true then won't I move the "hover" point up away from around center stick to "more" stick? Pls bear with me if these questions seem silly.... thanks, guys, tob > t...@sourcecode-inc.com wrote: > >> <t...@sourcecode-inc.com> wrote in message [quoted text clipped - 66 lines] > > Fritz At the moment I do not recall the specs of the motor (I'm away from home) but I think your idea regarding headspeed is in the same vein of my thought to The Beav regarding pitch... it boils down to a notion of the main blades currently imparting (more) rotation to the frame than I had when the V2 was a gasser; and so the tail rotational speed is not adequate anymore to keep up with the rotational torque. In 10 years of flying helis I can honestly say that I never had to "worry" about headspeed before (and so never purchased even so much as an RPM meter!) the kits all came out of the box, went together, and flew wonderfully ... I guess I'm paying for that now. That being said, perhaps I could ask for a little more education regarding headspeed. I'm guessing that since the tail can not even keep up when the heli is BELOW hover that means the throttle curve is already "too high". If I were to change the throttle curve to lessen the headspeed in the area below and up to the "hover point" on the stick, doesn't that just "move" the problem up into the higher end (i.e at higher throttle?) Unless you mean for me to take the ENTIRE CURVE down (i.e. all 5- points get moved to lower throttle point. And if this is true then won't I move the "hover" point up away from around center stick to "more" stick? Pls bear with me if these questions seem silly.... thanks, guys, tob >> t...@sourcecode-inc.com wrote: >>>> <t...@sourcecode-inc.com> wrote in message [quoted text clipped - 85 lines] > thanks, guys, > tob A heli hovers at a certain pitch at a certain headspeed. Common #s are 5 deg pitch and 1800 rpm. If you go to a higher headspeed, you need less pitch to hover i.e. 4 deg at 2000 rpm. And vice versa 6 deg at 1600 rpm. The speed of the tailrotor is a multiple of the mainrotor rpm. With the Raptor it is 4.56. So at 1800 mainrotor rpm, the tail turns at 8208 rpm. If the mainrotor turns too slow, the pitch required to hover is greater producing increased counter torque. Then the tailrotor is not spinning as fast reducing the efficiency of the tail down to a point where the tailthrust is not enough to overcome mainrotor torque. You need to set the mainrotor speed at a minimum of 1700 for a R30 to get a working tail. Since it's electric, you need to use a heli tach to measure the speed and adjust the throttle curve. Most electric helis have throttle curves of: Normal: 0, 40, 80, 90, 90. Idle Up: 90,85, 75, 85, 90. This is of course totally different from a nitro powered heli. If you can't get to a minimum of 1700rpm then you need to change some parameters in the power train. More voltage, bigger pinion gear, a higher Kv motor. My electric heli setup is like this. Normal Pitch curve is: 50,50,50,50,50% or 0 deg pitch all across. Normal Throttle curve is: 0, 35, 80, 80, 80 where 80 is the desired headspeed. It can be any number above 75% to 100%. This Normal setup is used for spooling up the rotors. IdleUp pitch: 0, 25, 50, 75, 100% linear curve, -12deg, mid 0 deg, high +12 deg. IdleUp Throttle 80, 80, 70, 80, 80. again the 80% is the # that will give you the desired headspeed. Fritz > Thanks, Beav... > [quoted text clipped - 11 lines] > "less air" (and I am hoping) therefore "pushing" the frame underneath > less rigorously than they do now?? You can do that, but the rotor revs will be higher, maybe even TOO high and of course as the battery dies off, you'll need to compensate for the loss of revs with more pitch and eventually you're back at square one. > And thanks for taking a stab at this! No probs. SignatureBeav VN 750 Zed 1000 OMF# 19 > <t...@sourcecode-inc.com> wrote in message > [quoted text clipped - 30 lines] > Zed 1000 > OMF# 19 I think overall all of this discussion has convinced me I need to take a good look at all rotor aspects of this converted ship... main blade static pitch (-3 to +something), headspeed, pitch and throttle curves, tail rotor size, etc... Even though I've been flying helis for a while, I have never had to worry (seemingly) about alot of this stuff when it was a gasser. The flat pitch curves (out of the box), minimal blade adjustments (mostly for getting a flat "plate", and sometimes having to adjust balance.) But these electric motors are a whole new experience, so I think I'll just take everyone's word for it that they don't fly right out of the box, and need attention to the details. Thanks to all for your ideas and suggestions! tob >Hi, > [quoted text clipped - 24 lines] >thanks, >tob My guess is the head's not turning as fast as it used to so the TR is now slower and just can't provide the thrust to overcome the torque. You DID massage your throttle and pitch curves after the swap, right??? You need to get the motor spinning around 80-90% for best efficiency and to keep the amp draw and temps down. Lugging the motor at 60% at 5 degrees of pitch will implode your batteries and potentially cook both the motor and the speed controller. All of my electrics helis (5 of 'em) run pitch and throttle curves similar to this: NORM: P - 40, 45, 50, 75, 100 (-3 to +10 collective w/0 at mid stick) T - 0, 60, 80, 90, 100 IDL1: P - 0, 25, 50, 75, 100 (+/-10 or more depending on the heli and how I fly it) T - 100, 95, 90, 95, 100 I play with pinion sizes to get the HS where I want it. The little helis (450 sized all run around 2800 RPM on the mains and the 50 sized bird runs right at 2100RPM in Idle up) None of these helis ever get the electronics hot. Highest temp I've seen was on a 92F ambient day and the motor got to a whopping 121F. Typical temps are in the low 100'sF for packs, ESC and motor. Fritz, why the throttle limitation in your curves, especially above mid-stick? Your pitch is coming up so you'll need more power to maintain headspeed... Are you using a governed ESC and leaving the top end limited so the governor has room to work? On Oct 8, 1:54 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia "DOT" net> wrote: > >Hi, > [quoted text clipped - 58 lines] > maintain headspeed... Are you using a governed ESC and leaving the > top end limited so the governor has room to work? Hi (Other) Kevin , I am really new to the electrics so thanks for all ( and to all !) for the great data regarding temps, speeds, and the like. So I assume that when you speak of 80-90% you mean at the HOVER point (if one does ALOT of hovering) and some throttle point slightly higher if I want to punch hi-speed holes in the sky in forward flight... thanks, tob >Hi (Other) Kevin , > >I am really new to the electrics so thanks for all ( and to all !) for >the great data regarding temps, speeds, and the like. Yeah, the electrics are set up a bit differently than the nitro birds. All but 2 of my helis are electrics so I'm most familiar with that type of setup. >So I assume that when you speak of 80-90% you mean at the HOVER point >(if one does ALOT of hovering) and some throttle point slightly higher >if I want to punch hi-speed holes in the sky in forward flight... Inb any flight condition you want that motor rippin' along at 80-90% of it's max RPM and you want to keep it there. When you spin 'em up, they suck as many amps and everything keeps cooler. The increase in throttle compensates for the increased pitch as you add collective. Some people even add a custom mix to add throttle as cyclic is applied to compensate for that additional pitch although it's easy enough just to feed in a bit more collective as you roll into a maneuver. I don't like the governor mode in my current ESCs so I use the throttle curves to keep headspeed at a steady level throughout the flight.. It's not perfect, but the variance is never more than about 300 RPM. Just think of the mains as a big constant speed propellor... ('cuz that's what is is...) Just out of curiosity, what motor/batts are you runnin' with that conversion? On Oct 8, 4:20 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia "DOT" net> wrote: > >Hi (Other) Kevin , > [quoted text clipped - 27 lines] > Just out of curiosity, what motor/batts are you runnin' with that > conversion? Interesting, since as a gasser, I keep the throttle and pitch locked together (they both go UP and DOWN) ... So electrics really want to operate like "constant RPM" props, then just vary pitch; I think I can see that. I have a Raptor 30 V2 converted using an ACE-65A (its the 'heli' version) ESC, a Z50A-800 brushless, and 10s a123 (Lithium Iron Phosphate) cells (from a dewalt battery pack!) thanks again for all the great info. tob I have the "governor" mode disabled on the ESC. >Interesting, since as a gasser, I keep the throttle and pitch locked >together (they both go UP and DOWN) ... So electrics really want to >operate like "constant RPM" props, then just vary pitch; I think I can >see that. Gas, electric, rubber band, nuclear, doesn't matter. As you change pitch, the power required to maintain that headspeed increases so you've got to add throttle as the pitch increases and decrease throttle as the pitch decreases - which prompted my question to fritz re: his throttle curve setup not adding power as pitch increases. >I have a Raptor 30 V2 converted using an ACE-65A (its the 'heli' >version) ESC, a Z50A-800 brushless, and 10s a123 (Lithium Iron >Phosphate) cells (from a dewalt battery pack!) I gotta try those A123 cells one of these days. $300/pack for my Trex600 is ridiculous. On Oct 9, 10:04 am, The OTHER Kevin in San Diego <skiddz "AT" adelphia "DOT" net> wrote: > >Interesting, since as a gasser, I keep the throttle and pitch locked > >together (they both go UP and DOWN) ... So electrics really want to [quoted text clipped - 13 lines] > I gotta try those A123 cells one of these days. $300/pack for my > Trex600 is ridiculous. this deal with getting them on ebay gets you a 10s (36v) for about $10/ cell. And all it takes is 10 minutes (and a dremmel tool !) and you've got yourself a nice, pre-soldered pack On Oct 8, 4:20 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia "DOT" net> wrote: > >Hi (Other) Kevin , > [quoted text clipped - 27 lines] > Just out of curiosity, what motor/batts are you runnin' with that > conversion? Interesting, since as a gasser, I keep the throttle and pitch locked together (they both go UP and DOWN) ... So electrics really want to operate like "constant RPM" props, then just vary pitch; I think I can see that. I have a Raptor 30 V2 converted using an ACE-65A (its the 'heli' version) ESC, a Z50A-800 brushless, and 10s a123 (Lithium Iron Phosphate) cells (from a dewalt battery pack!) thanks again for all the great info. tob I have the "governor" mode disabled on the ESC. On Oct 8, 6:43 pm, t...@sourcecode-inc.com wrote: > On Oct 8, 4:20 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia > [quoted text clipped - 45 lines] > > I have the "governor" mode disabled on the ESC. And I have a 110 tooth MAIN, with 9 tooth pinion on the motor.... the tail belt gear under the main is a 45 (or maybe a 41) tooth.... and I have NO IDEA what gearing is in the tail assembly to turn the tail blades. On Oct 8, 6:43 pm, t...@sourcecode-inc.com wrote: > On Oct 8, 4:20 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia > [quoted text clipped - 45 lines] > > I have the "governor" mode disabled on the ESC. And I have a 110 tooth MAIN, with 9 tooth pinion on the motor.... the tail belt gear under the main is a 45 (or maybe a 41) tooth.... and I have NO IDEA what gearing is in the tail assembly to turn the tail blades. > On Oct 8, 6:43 pm, t...@sourcecode-inc.com wrote: >> On Oct 8, 4:20 pm, The OTHER Kevin in San Diego <skiddz "AT" adelphia [quoted text clipped - 43 lines] > have NO IDEA what gearing is in the tail assembly to turn the tail > blades. It sounds like you need to get an idea of the tail rotor gearing. You may want to contact the folks who made the conversion kit. IMHO, it almost sounds like they forgot to send you something for the tail rotor. But that's just me, since I fly completely different birds than what you are talking about. marco |
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