View Full Version : Tail Control authority
Hey guys, I've got a Raptor 50 running a headspead of 1800 that I can't seem to get enough speed (control speed) on the tail with. I can bury the rudder stick left or right, but I just can't get it to really whip around like I would think it should. I'm running a GY401 gyro and I have the limits set to allow me as much travel as possible. Should I be running a higher headspeed in order to get more authority over the tail?
Thanks much
=JaitiCsa.k
Eric Lis
07-31-2006, 12:26 AM
probably need to set the atv higher the 401 is capable of spinning it faster then you can count well almost..... :)
flyinfool
07-31-2006, 09:29 AM
A faster tail speed will help.
You can either up the head speed or put in a tail speed up gear, (http://www.gohbee.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=50139&Category_Code=1100) or experiment with different tail blades.
But there is likely a setup problem in your 401, as Eric said it can spin awfully fast.
ClayK
07-31-2006, 09:49 AM
Define "fast" :dontknow
Mine has been a bit sluggish as well.....
Eric Lis
07-31-2006, 10:14 AM
fast would be 2 -3 revolutions per SECOND not where you would run it but capable of doing it.
ClayK
07-31-2006, 10:17 AM
hmmm.... mine's slow then. Mine's about 1-2 revolutions per second. Obviously quicker one way over the other.
BarracudaHockey
07-31-2006, 10:30 AM
Could be one of two problems, those plastic tail blades aren't very stiff but I've seen one spin like a blender with the stock blades so it can be done.
Also if you subscribe to the theory of running up the gyro gain until it wags then backing off a hair you need to do it correctly, that is just enough gain to hold in the most demanding manuver you are capable of (your servo will thank you for this)
But assuming your gyro is setup correctly upping the atv's will increase the piro rate, take it slowly, anything over 100 starts to really ramp things up, I'd go 5 percent at a time.
Clay you can off set the atvs on the rudder to get symetrical piro rate.
Mine is maybe 1 to 1.5/second. I don't know what could be holding it back in the 401 though... I have the limit set to go to full extention on the pitch, the delay set to 0 (9254 servo), and about 85% on the gain. I do have my ATVs reduced on the rudder channel though... they are setup so that when I reach full throw on the transmitter I also reach full throw on the servo. In other words, it is set so that I don't reach the end of the servos range way before the end of my stick range. This making any sense???
Could it be that the gain needs to be lower or something??
-Lee
Eric Lis
07-31-2006, 10:17 PM
syn like Andy, and I both have said set the rudder atv to 100 and then see the difference adjust as necessary. It doesn`t sound like you have the end points set properly if you are using atv to limit travel. What radio are you using?
flyinfool
07-31-2006, 11:46 PM
it is set so that I don't reach the end of the servos range way before the end of my stick range.
That is your problem.
You use the ATV to set your piro speed and the 401 to control how far the servo moves.
The rudder does not work like the other channels, the TX does not tell the servo how far to move. The TX tells the gyro how fast you want to turn and the gyro then does whatever is necessary to the servo to make it happen.
Crank up your ATV. to at least 100% and make sure that the tail pitch slider can get to the stop in both directions.
I'm using a JR 8103, but I'm not using the ATVs to limit travel... that is being done via the gyro. I was just usign the ATVs to make it so that when I went full stick on the transmitter the servo was at full throw then also. Without using ATV, the servo reaches full throw (as limited by the gyro) at about 1/4 of the throw on the transmitter stick. Maybe I just need to make a video to describe this... :mrgreen:
In any case, I'll go fly it tomorrow without any ATV on the tail and see how it does... I'll let everyone know.
-Lee
flyinfool
08-01-2006, 09:29 AM
I am not familiar with the JR radios so I am not sure exactly what you are doing.
But if you are limiting travel from the TX, that is not right.
It is correct and normal for the servo to reach full travel long before the stick gets to the ends of its travel.
Like I said above, the stick on the TX does not control the servo, The stick on the TX only tells the gyro that you want to turn, and how fast you want to turn.
So what you are seeing is that you give a stick input and the gyro gives a servo input, but because the heli is on the bench the gyro keeps giving more servo input trying to overcome whatever is keeping the heli from turning, that is why the servo gets to the end much faster than the stick.
This is both hard to explain and tricky to understand.
spork
08-01-2006, 09:43 AM
This is both hard to explain and tricky to understand.
Here's a real easy way to see what's going on. Have the wife hold your TX with the rudder stick full-over. Your servo is at the limit because you set the 401 limits properly. It also took nearly full stick to get it there because you set your ATV's that way.
Now, hold the bird and spin around as fast as you can - you and the bird. I think you'll see the rudder servo is nowhere near the end of it's travel while you and the bird are rotating. This is what happens in flight.
Now if you increase your ATV's a bit so the servo reaches its limits before full stick deflection, you'll find that it still does the same thing when spinning, but gets closer to the limit while you and the bird are spinning. Increase ATV's enough and you'll be able to reach the limits even when spinning.
The easiest way to understand this is to think of what the gyro does in non-HH mode. It is simply a proportional negative feedback device. In other words the faster the heli is rotating the harder the gyro tries to make it stop. It doesn't matter if the heli is spinning because you told it to, or because the wind is blowing it around. In order to get full rotation you have to tell it to spin much faster than you really want, because when the gyro senses the spin, it's going to slow it down a good bit.
RC
flyinfool,
Looks like our posts crossed, i posted my last reply before reading yours... Now after reading the posts that you and spork made I completely understand. I'm heading to my "test flying spot" right now to give it a try. Will report asap. :)
-syn
HAHA!!! That did it. I was actually wrong when I told you guys I was limiting it on the radio though... apparently I had taken that out and set it back to 100% at some point. Still though, your advice helped because I just jacked it on up to 150%... now that is freaking fast. :) I can't wait to get back out to the field with this joker now. Too bad I gotta fix this high frequency rattle that it developed. :arggg:
-syn
flyinfool
08-01-2006, 10:52 AM
There is another trick you can use to get insane piro speed.
Set up the radio wit a P-Mix of rudder as master and gyro gain channel as slave.
Set this to work only in non heading hold mode.
Set up the mix so that as you increase the rudder input the gyro gain goes down.
What this will do is to prevent the gyro from fighting the rotation.
You will find that the piro rate can get to faster than you can see the heli spin.
If you try this make very sure that you will not launch the RX or Battery from the centrifugal force (It is real exciting when that happens)
flyinfool
08-01-2006, 10:55 AM
Now that's a flying field.
You went from posting here to a test flight and post the results in just 14 minutes.
I'm impressed.
ClayK
08-01-2006, 11:00 AM
My solution is pretty easy.... I hand it over to Charles and say "Fix it!" :glasses2:
His response is usually "Why do you think it's not working" :arggg: He wants me to learn or something.....
My ATV's are at 100%. I'll have to check it out when I get home. Hard to say what it is from memory, but I'm pretty sure it's just crappy setup. I might need to have that gyro class again....
no no, that is the "test flying field".... or my back yard, whichever you wanna call it! :) I just picked it up, did a piro, put it down to set the ATVs to 150, did another, then landed giggling like a school girl. :mrgreen:
-syn
flyinfool
08-01-2006, 01:30 PM
Clay we'll get you spining at IRCHA.
Syn-
Glad to hear it's better now.
If you use the P-Mix I mentioned above it will get even faster.
ClayK
08-01-2006, 02:18 PM
I hope to be back up in the air this evening. The "itch" is back at me again. I plan to be working on the Spectra a little bit while this intense heat is upon me. After dinner, I'll take Rappy back out for a spin.
BarracudaHockey
08-01-2006, 03:09 PM
Take a look at your gain now.
Fly as fast as you can sideways and or backwards, use only enough gain to hold the tail. Any more than that and you are over working your servo.
Ok, so now that I have this thing spinning like a top, I've got another question on the setup for the cyclic servos. This is what I have been told to do so far:
- set everything up nice and even with the swash leveled using a swash leveler
- disconnect the collective linkage from the servo so that the arm can be moved up and down by hand.
- turn on the radio and put the cyclic stick in one of the corners
- try to move the collective arm, if it binds, then you have too much cyclic throw.
Ok, knowing that is all good and well, but how should I approach fixing it? Currently, I just reduced my throws on the two cyclic servos until it didn't bind. Is there some approved method for doing this? Should I reduce the throw on the "aileron" and "elevator" channels by the same amount until binding stops, or should one be reduced more than the other? Is there a way to measure how much throw I'm getting to see if it falls within the range of "normal"? Can one of you gurus just move to my neighborhood so I don't have to keep posting all these questions? :mrgreen:
-syn
Will do barracuda, thanks for the tip. ...I've got a lot to learn in a little bit of time when it comes to setup. It appears my constant obsession with computers and simulators has my flying skills ahead of my building skills. haha
-syn
BarracudaHockey
08-01-2006, 03:55 PM
Cylic setup.
Level your swash, set mid stick (0 degrees pitch) and put a pitch gauge on.
Check for 0 degrees at several points about the rotoation, this will ensure your swash is level.
Set the blades straight out and back, give full right aileron and measure the pitch, any more than 6 or 7 degrees (at the most) reduce your atv's till its there, turn the blades 90 degrees and do the same thing with the elevator.
If you have to go too far with the atvs say 80 or so, move the balls in one hole, put the atvs back to 100 and start over.
More swash throw isn't always better.