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RE: Airplane rudder gyro
Hello, I have a scale plane (sound familiar?) and I was wondering if a JR G770 3D was a good selection, and how to set it up so I can turn off the heading hold after lift off?
I would really appriacate the insight of those who have gone down the runway before. Sean |
RE: Airplane rudder gyro
Hi Sean,
Do you have the Dec issue of Model Aviation? I give the whole approach to do it in there. Look it over and if you still have questions come back to this forum and someone will have an answer! The JR G770 3D is a super gyro and I have three of them in airplanes that I value a lot. In airplanes that cost less a less expensive gyro would seem reasonable. Make the gyro cost proportional to the value of the airplane and how much it is worth to you. The HK 701 has gotten good reviews in this forum. Do a search for it. But do read the magazine article first. Also knowing the particular transmitter brand and name would be useful. Ben |
RE: Airplane rudder gyro
Thanks, I don't have that issue, I do beleive thats where I saw the suggestion. The transmitter I am using is a Spektrum DX -7,receivers are AR7000 with the dual receiver. I have currently a glider (learned on) an Ultra Stick 60 with an os max Surpass FS.91, a pattern plane I picked up at swap w/ same engine, (not finished yet) and a scale cub from an unkown manufacture thats a 1/4 body and 1/5 scale wings ( though its not a clipped wing cub). This is what I picked the gyro up for. I have seen other Cubs waddle and spin from even some seasoned pilots. This isn't reassuring for a guy flying for 5 mos.
So that's the story,I picked a Gyro up second hand for $80. (JR G770 3D) I uploaded the instructions from JR. Sean |
RE: Airplane rudder gyro
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hckyfntk,
I just installed a gyro into my cub on the rudder. I'm working on a video presentation showing a gyro installed on the rudder for what you are talking about. Thanks to Ben's article there has been an explosion of gyro use on Rudder. Although I'd done it on the rudder before. I'd mostly done it on the Ailerons for the wind. But I am at a grass field. There are others flying on pavement where it's much worse. I'm using a GY48V and a DX7 but Im going to try to keep the video generic as well. I have a little foam board with some servos mounted to it and gyro attached to something with mass. I hope to get the video up tomorrow. As Ben says, that gyro will do for that plane. It will mount lable side up. Find a surface to mount it parrallel to the horizontal plane and that will handle the YAW axis. Your gyro would be mounted like mine is for the Yaw(rudder) axis. Here is a pic of my gyro mounted in my cub for reference: |
RE: Airplane rudder gyro
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Hi Hckyfntck,
I am looking forward to the movie - they are hard to beat as far as learning stuff. Meanwhile in a summary version - you connect the gyro plug into the rudder output of the receiver. You connect the single wire from the gyro into the retract output of the receiver (you could also use any other switch on the transmitter). Plug the rudder servo into the gyro. These three wires can only be connected in one way. On the transmitter go to the landing gear ATV (servo travel limits or what ever it is called). When the gear switch is in one position the gyro will be in the Heading Hold mode (HH). When the gear switch is in the other position the gyro will be in the Rate Dampening mode (R). You will need to set the ATV for the HH mode to around 70 to start with and the ATV for the R mode to about 10. These are just beginning numbers but do seem to work - all they do is determine how effective the gyro is. When you turn off the gyro (set to the R mode) you really don't want it too effective but you also want a little to be sure the gyro has switched over to the R mode. On the HH mode side you will end up selecting a number that gives you the rudder throw that seem reasonable. Truthfully I have found that my airplanes have worked well with a host of different rudder throws in the HH mode. The gyro is always doing a better job than I can. Now you have to set the switch on the gyro to normal if the rudder servo is not a digital servo otherwise it will burn out the servo. Then you have to set the other switch to norm or reverse to get the response out of the gyro to the rudder servo right if the airplane nose swings right the commanded rudder is to make the airplane go left. You might have to reverse the landing gear switch too to get all of the things aligned OK. Note that this is the same kind of approach to settings that is used in setting up the gyro in helicopters. When you are finished you will be able to move the fuselage something like 15 degrees and the rudder will respond in the opposite direction to stop it. I'll attach some photos from the article. Three are the airplanes I tested and one is an example of the airplane yawing with the rudder response. email me at [email protected] and I'll send you a copy of the text since this beast is fighting me about it :-) Look in some of the past postings that I have made and you will find the movie made of the flight testing of the gyros. Ben |
RE: Airplane rudder gyro
ORIGINAL: otrcman I hesitate to write this, because I don't want to "take the bait" from those who have questioned the use of gyros in model airplanes. But there is a perfectly valid argument for the use of stability augmentation (gyros) in models, just as there is a valid argument for the same use in some full scale airplanes. First off, let me establish that I am fully qualified to make this argument. I am a retired flight test engineer, having been involved in testing airplanes from X-15 and Space Shuttle, down to simple light airplanes. A great portion of my career has been in studying the man-machine interface of a pilot flying an airplane. I have a bachelor's degree in Aero Engineering (Cal Poly 1964) and a Masters in Systems Engineering (USC, 1989). In addition, I am a commercial pilot and flight instructor, specializing in training pilots to fly full scale vintage tailwheel airplanes. I have made approximately 15,000 takeoffs and landings in various tailwheel airplanes. 1. Here is the bottom line reason why gyros can be useful to us in our scale models: Model airplanes are not real airplanes. But we modelers want our planes to behave in flight like their full sized counterparts. We work hard to make them look real statically and we want them to look real in flight. Gyros help us do that. 2. Why can't we just fly them like a full sized pilot flies his plane ? Scale models have the same shape as their real counterparts, but they do not have the same mass or size and therefore they move differently and look different when they move. Essentially, they have higher angular rates (less inertia, less damping) and they respond much more quickly to upsets such as atmospheric turbulence. 3. We model pilots are human beings just like the pilots of the real airplanes. We have pretty much the exact same response rates, accuracy, and lag times. Controls engineers call this "the human transfer function". Transfer function describes the way we respond to a task and how quickly we begin to lag in our responses as the task speeds up. The argument raged between test pilots and engineers for a long time that some pilots are more skilled than others. But today it's pretty much universally agreed that a human being who is trained for a task exhibits responses which can be mathematically modeled and are readily predictable. 4. The task of the model pilot is further hampered by the poorer visual cues. We can't look straight down the nose like a pilot of a full sized airplane. Visually, flying a model is more like shooting from the hip as opposed to sighting down the barrel of a rifle. 5. And the task of the model pilot is still further hampered by our lack of "feel" in the seat of our pants when the model airplane moves. So we model pilots are the same sort of human beings as full scale pilots, but the task is different. Therefore, the outcomes can't be matched. The gyro simply adds apparent size to the model in terms of body motions. The airplane swings more slowly, responds to gusts less, and doesn't overshoot in its response to our inputs. In short, the model becomes closer to the real airplane in its behavior. This enables us to interact with the model in a more realistic fashion and pleases us because the visual appearance in flight more closely matches the realistic static appearance. Are there folks who still don't get it ? Sure. I wrote this for those who appreciate what the gyros are doing for them and to help them understand WHY it helps. Can't help the others. Dick Fischer What you said about the behavior of our models is so true. Did you meet any of the topguns while fiddling around withthe X15 ? This thread is <u>really</u> interesting. Thanks everyone for your inputs. http://www.rcuniverse.com/forum/js/f.../thumbs_up.gif -Paul |
RE: Airplane rudder gyro
Installing Gyro in Rate mode on Rudder (revised)
Part 1 http://www.youtube.com/watch?v=rFXiImpRQV4 Part 2 http://www.youtube.com/watch?v=RPmoIz2Q8DE One more video is comming, plus I need to update the website too. |
RE: Airplane rudder gyro
More info vids. This covers less of the how to install and more on operation/theory/use/tips
Part 2 I think has the most usable content Part 1 http://www.youtube.com/watch?v=J4_q3NnDBu8 Part 2 http://www.youtube.com/watch?v=IEUl0Yyryb8 Part 3 http://www.youtube.com/watch?v=43uYHsioabY |
RE: Airplane rudder gyro
subscribed!
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RE: Airplane rudder gyro
Good videos - the only thing I would caution about is using HH mode on landing.
It is fairly easy to line up on the runway (if you are lucky enough to have one) and go to HH mode on takeoff, switching it off when a couple of feet in altitude. But on landing getting the fuselage aligned with the runway could be difficult and if you switch to HH mode too soon (say 20 ft high) you could find yourself landing in a cross runway direction or not having the ability to slip the airplane in to the runway. I don't know for sure since I haven't tried it personally - summer will get here soon though! This potential problem could be helped by waiting until the airplane was only a couple of feet off the ground and definitely going in the right direction - then going to HH mode, letting the rudder and eventually the tail wheel handle the landing/groundlooping chores. The sooner you could get weight-on-tailwheel the better the runout would be. Ben |
RE: Airplane rudder gyro
The videos are very good. One thing I would add is that you do not want to move the control stick when in HH mode. For example, when using HH mode on rudder on takeoff, do not move the rudder stick or you will get into trouble. You must let the gyro control the rudder until you move to the rate or off mode. I do this by programming a mix which in effect turns the rudder stick off when in HH mode and on in off or rate mode. On the Futaba radios I assign the mix to the same switch as controls the gyro mode and when in HH mode x and y are both set to -100 and when the switch is in the other positions x and y are both 0.
Bruce |
RE: Airplane rudder gyro
thx for the quick feedback. Those vids will be re-shot/edited so contribute all you can before I do that.
I'm not so sure about turning rudder off, especially on take off. If the wind is pushing you towards the pits, you may need the rudder to give yourself some yaw input w/o having to use ailerons, or in addition to ailerons. I have a grass runway, I see people lining themselves up incorrectly all the time. Since our runway is VERY wide, they get away with it. I learned RC on a paved runway that was like a 2 lane road and Pilots were on the edge. No room for error. w/o rudder input, once they get going, to say that they need to hold that nose heading till they take off and switch off I think may not be the best thing. Planning the take off is best, but I want to think about setting up the novice gyro pilot for something a little more foolproof and less to think about/program. HH mode, the gyro want the rudder input to tell it the rotation rate. This is how it was designed for helicopters. 1/2 stick (with 100% travel adjust) for example is a given rotation rate. The helicopter want to move at that rotation rate and will give what ever tail input is needed to achieve that. Helicopters can yaw/rotate MUCH faster than a fixed wing. So what I have found is that in HH mode, I often need some expo or dual rates or it will make the sticks REALLY sensitive. In the case of my last foamie with a gyro, I put in some dual rates on a switch as well as expo. I can give yaw/rudder input when I need it and it is not so sensitive that I get into trouble. I keep getting back to the idea that Rate mode (even on rudder) is probably the best way for someone to introduce themselves to a gyro on an airplane. Be it for yaw,pitch or roll axis. Except for putting your gain too high, it's much harder to get into trouble in Rate mode than HH mode. |
RE: Airplane rudder gyro
BTW, as far as rudder control on landing. Watch this video at 3:35 when the black DR1 lands
http://www.youtube.com/watch?v=1msZVTJqEBM This is a VERY experienced pilot. However, he does not fly that bipe that often. Not a great setup for the landing and it flips over. The other pilots who land after him fly less often, but fly their BIPES probably 10x more often than he does. The experienced pilots know the right airspeed for the landing approach, rate of decent etc and what to do with the rudder in the crosswind. I have got to believe that with a rudder on the tail in say Rate mode at least, the first pilots landing would have gone better. His Yaw turned into a hop and skip that then turned into a flop. It's on landing that I see more flops and such sometimes it's due to a gust messing up the roll axis, other times it's the crosswind gusts yawing the plane making its heading change just before touch down. |
RE: Airplane rudder gyro
dditch, I want to complement you on the videos that you have produced. They are well done and the video quality is superb. Very clear on my HD monitor in full screen. When you get the modifications made please post all of the links in one post. For what it's worth I would not feel comfortable killing the rudder stick in HH or landing in HH. On my plane HH (+70) is only used for takeoff. I always use Rate (-70) while flying.
BTW what name do you go by? |
RE: Airplane rudder gyro
Thx, Name is David.
I took the Cub out today and got about 6 flights on it. Nothing but testing pretty much. Up until now, I'd have to say that the planes I put gyros onto the Rudder did not really need it. I had been doing it for the sake of experience. Those planes typically had Gyros on the ailerons though for wind stability which being light, they found more use for. Well, the cub on the clumpy grass I fly at, made more use of the gyro than the other planes. I however DID NOT LIKE the gyro in heading hold mode. The trouble was that about 75%+ of the time, I HAD to make some corrections to the yaw axis during take off which resulted in a change in heading that screwed things up. The problem is that with the clumpy grass, sometimes one wheel can stick in the clump and yaw the plane, the speed is too slow for the rudder to take effect and on this plane, the tail wheel is a bit loose (I damaged it one day taking it out of the car and now there is some play in the wheel). So quite a number of times, I could NOT simply line it up, hit HH then just take off w/o touching the rudder. It simply took too much space before the gyro started to correct the heading being off 10,20 sometimes 30 degrees from center of the runway because of hitting those clumps as I started my take off roll. So I changed the programming to be RATE MODE/OFF instead. I went ahead and did some take offs/landings with the gyro off. I could see how I had to be very active on the rudder to compensate. Even so, there was some wiggle time to time as my reaction speed to visually picking up the yaw from a side prospective was not superhuman. I then turned the gyro to Rate mode and did some aborted take offs, adjusting the gain up a few times until I got to about 80% gain in rate mode. The response was awesome. Some corrections were needed from time to time to get the right heading, but it took off with significantly less input and that input was small corrections. I was able to do 2 wheel scale takeoffs/landings time after time. I'm sure things would be different if my tail wheel was better and/or if I was on a paved runway, but after today, I think I'm gonna re-shoot that video. I think that running Rate mode for the rudder on take off and landings is an easier way for someone trying out a gyro to start with. Because the Rate mode damps, having a low gain and working your way up, does no harm compared to when the gyro is not installed. If you run heading Hold and your gain is too low, I think some circumstanaces, it will make things worse. Especially if you have some slop in the controls or a rough surface to take off from. I shot some video showing the differences between with and without the gyro on take off and landings. I'll post that once edited. David |
RE: Airplane rudder gyro
Trust me, having it in heading hold with too much gain is worse :)
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RE: Airplane rudder gyro
The speed and torque of the servo also makes a difference. As does the location of the control rod ends in regards to their locations relative to the center of rotation - servo horn, and rotating axis of controlled surface.
These are just two items that can easily affect the response time and strength of the gyro controlled item. |
RE: Airplane rudder gyro
Videos in Post 556 have been revised
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RE: Airplane rudder gyro
ORIGINAL: Silverexpress The speed and torque of the servo also makes a difference. As does the location of the control rod ends in regards to their locations relative to the center of rotation - servo horn, and rotating axis of controlled surface. These are just two items that can easily affect the response time and strength of the gyro controlled item. thx |
RE: Airplane rudder gyro
The lumpy grass and the planes physical makeup takes it to the limit though - meaning a more powerful (and expensive) servo may not be of much help. Best to look at other variables.....such as a different surface (mow it, fill in the divits, lay down astro turf, plywood, plastic matt, asphalt...etc), lighten up the plane, rearrange the landing gear, put bigger wheels on it...etc...
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RE: Airplane rudder gyro
My comment was to agree that those things will affect general gyro performance. I agree they won't help me with my field very much.
Don't think I can control the divets and especially the clumps of deer poop that pops up (or drops down). Better servos, tighter linkages (no slop) and the right amount of mechanical movement has a great affect when putting a gyro on the ailerons. |
RE: Airplane rudder gyro
Man this is a lot to review!, I can't thank all enough and it seems this is a great topic!
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RE: Airplane rudder gyro
I just rec'd the 2.3g rate gyro from HK [link]http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=4320[/link] and tried it on the ailerons. It works great. I had the gain on lowest and I will be able to add a little more. It's in my Parkzone Extra 300 which is so solid and holds the bank easily now in 15mph winds. On low rates when I hit max elevator up or down, she just goes up or down and does not spin out any more. But on high rate max elevator causes some spin out, but not much. I've done the 3d tail sweep, it's so cool. And knife edge is easy. And inverted flat spin is the most awesome move yet. But I couldn't hold a hover, I'll try the 12/6 prop others say works better.
So I added the HK401b gyro on the rudder this time, and in a hover, it held the tail straight up very well. At the same time I put on the 12/6 prop and it helps 3d a lot, but is much slower than the 10.5/9 oem prop. But when I just flew straight, the rudder wagged a lot so the gain was too high, but this gyro doesn't have a gain control on the gyro itself like my 2.3g rate only gyro. It's meant for heli's so you have to do the gain control in the Rx. I didn't know that until a few days ago. I read here that on a DX7 you use the Travel Adjust on the channel you plug the extra lead into, in my case it's the gear. So I changed the Travel Adjust to +28% for the HH and -28% for the rate gyro. I mostly use the rate. I've used HH on takeoff and landings sometime, but I haven't needed it even in a strong cross wind. I have a very rough grass/weeds field to fly in. With the 12/6 prop and both gyros at about 30%, I can tail land the Parkzone Extra 300 now! I can also fly her VERY slow, nose up. I have all servos at max throw. Mike PkZn Extra 300 with 2 gyros, PkZn Wildcat, 3' Pitts Sukhoi BL upgraded 2 cells, 6' EZGlider with BL launch motor Super Cub BL wt moded ailerons, slo-v BL, Tx DX7 Function over ALL else my photography: http://BesPhoto.com |
RE: Airplane rudder gyro
new format to gyro info page:
http://www.mycoolrc.com/gyro/indexnew.html |
RE: Airplane rudder gyro
Boy I wish I would have found your posts a month ago when I tried the HK401b in my Parkzone Extra 300 on the ailerons. From what you've taught me I was in HH mode and was lucky enough to land and disable the gyro for the rest of the flights. I now think I'm setup good on ailerons (rate only) and rudder (gear switchable between rate and HH) and have had many great flights using them. I love to be able to fly in the wind without any problems. I live near Chicago, the windy city. Actually landing is easier in the wind than otherwise now.
Now I have to figure out if I can put the 2.3g gyro on my modded 60 g AUW two cell BL Parkzone Sukhoi su-26 (original). It is so wild in the wind, maybe I can tame her. Thank you Mike PkZn Extra 300, PkZn Wildcat, 3' Pitts sukhoi BL upgraded 2 cells, 6' EZGlider with BL launch motor Super Cub BL wt moded ailerons, slo-v BL, Tx DX7 Function over ALL else my photography: http://BesPhoto.com |
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