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Gasser Model RC Helicopters > Ever deviate from the pure linier pitch curve ??
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Was thinking if I flattened my my pitch curve just a tad at the hover point I might reduce a bit of the reaction and soften the collective a bit by getting a wee more stick travel. Kinda like a mecahnical Expo.


Had to ask !

OK X GAs let me have it !!!

Hey F3C Franny !!!! Wake up from yer NAp - whacha think ??

greyeagle
07-24-2008 02:29 AM
 
 
playfair
Key Veteran
Location: Rochester, NY

I sort of did this to my Trex450 in one of the idle up modes.
I tried to put some "expo" around the inverted and upright hover points (pt2-3,5-6) using the 7pt curve of my 9303. Limited sucess, as I usually prefer the "linear" feel.

On another bird I actually calculated what the blade pitch should be at each of the 7 points along the curve, and fine tuned the values to match. Variation from the "straight line" was give or take a few points. Overall, it probably wasn't worth the effort.


The sky is our canvas
07-24-2008 02:36 AM
HOMEPAGE  
 
 
Toadster25
Veteran
Location: Iowa

I kind of do that for my first position flight mode. I don't need very much negative pitch in normal mode because I don't ever plan to flip it upside down and if I do it will be bad anyway since the engine will go to idle. If you don't put very much negative pitch that can give you more stick travel. I don't usually fly in normal mode though.
07-24-2008 04:17 AM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

I got plenty of head speed

Recent Tach on the 1005, SE Hanson came right in at solid 1780 rpm and I got a pretty fat transistion through the low speed circuit into the HS on the 167. I think the carb puddles a bit during the circuit change over.


RPM is right at the sweet spot with the SAB"s 680's I just want a smoother collective as I transition out of FFF cause I'm always too high.

To me it's kinda like a small block with a touchy cam, I'm always ahead of it, a little stick goes a long long way's " Good stuff "

greyeagle
07-24-2008 04:28 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Gees Grey, it has been over a year now since I suggested it and now you are finally coming around. I have no idea where your points are now but back then they were in this range. Don’t go to shallow around hover or it will feel like you are loosing your stick.


I will also recommend again that you set your hover at midstick because you only have 5 points to work with and you are obviously not a stick banger or you wouldn’t be looking to smooth out the hover point.

Ace
What could be more fun?
07-24-2008 11:23 PM
 
 
Wa11banger
Elite Veteran
Location: Huntsville, Al

I have one model with it, I am experimenting with hurricane looking pitch curves that are not expo in the middle but hyper sensitive. So far I am liking it but it has taken some getting used to. It has increased the pop efficiently a little and made for some interesting manuevers as I get used to how little the stick has to travel to do the same job.

RIck

Proud member of the Quick UK, Duralite Flight Systems, V-Blade, KBDD & Compass Model teams
07-24-2008 11:28 PM
HOMEPAGE  
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Thanx Ace

I had to print it - We played around with this what maybe a year ago ??

For a while I was having trouble dialing in the head speed till I discovered the flat plateau throttle curve and a good buddy purchased a tach - now their spooled right up their with a bit more room to go.

Now that I got the head speed up, it's a question of feel I'd like.

For one : I know I have too much cyclic at 6 degree " non- binding" and even with 15% expo it 's still a little balancey.

The soft plateau around the hover point has lots of merit and I'm going to really chase it for awhile to see if I caan get what I'm looking for. THANX : Sincerely as I'm adding your plotto the others I keep on file. Good Stuff to see it physically.

I'm trying to achieve the feel of an old school pattern ship for Ffing
FF and once I get- it I'm sure I can pile in the + = - pitch curves till I reach the motor limits then back em off a bit. I'mm thinking of trying to get to axial roll's and Big round loop's some day.

I really look forward to when I can come in on a fast low approach and don't balloon.


Thanx !

greyeagle
07-25-2008 02:01 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
I really look forward to when I can come in on a fast low approach and don't balloon.

I don't think this has to do with pitch curves. It has more to do with pilot skill. Just like a plank, if you burn your way into the runway and nose up at the end it is going to puff up like crazy. In a heli you have the advantage of pitching the blades so if you nose up at the end of a high speed pass you have to counteract the lift with negative collective to keep it from rising.

If you give me what your pitch curve is right now I can plot it and suggest some numbers for a soft hover. I need the numbers out of your radio and the collective swing (lowest neg degree and highest positive degree of the blades).

Ace
What could be more fun?
07-25-2008 01:39 PM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Take a peek at these - both of my gassers's

Info is from my last data card's :

MA SE 1005 w /Hanson 5/3/08
Pitch Curve

1 48% -5
2 65% = 0
3 80% +4
4 89.5% + 7
5 95% + 9

Throttle Curve
1 = 8%
2= 55%
3= 67%
4= 72.5%
5= 95.5%


MA 1005 Sort of Stock 4/22/08

Pitch Curve

1 40.5% -6
2 49.5% -1
3 62.5% +3
4 79.5% +7
5 94% +9


Throttle curve

1 = 8.5 %
2 = 27.5%
3 = 33.5%
4 = 53%
5 = 97.5%



Thanx in advance !

greyeagle
07-25-2008 09:30 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Well Grey, I got some good news and some bad news.

Good news: Your plotted points agree graphically with what you stated for MA SE 1005. The percentages in the radio come pretty close to the actual pitch angle. Notice the scale on the right agreeing with the plotted points.

Bad news: This is a very bad mechanical setup in my view or your radio has a very funky programming scheme. It looks to me that you have given up over ½ of the resolution of the servo with your negative pitch starting at 48%. I would guess that you have a control arm on your servo that is too long and then you compensated for that by backing off with the ATV settings.

Before I recommend how to soften the hover point I would like you to redo the mechanicals so 0% = -5 and 100% = +10. I thing most of your pogo effect is cause by your mechanical setup.




Ace
What could be more fun?
07-28-2008 05:54 PM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

I'll check it again, pretty sure that's got to be it.

Your correct in that the Stock 1005 doesn't have the Pogo feel as much as the SE.

It' started after I installed the SE carbon front end, and at the same time installing a Pro Head. It's got to be in a linkage or arm length some wear in the geometry.


I'll go in, check the 90 degree centers the arms, total collective mecanical travel " - = + " Zero out, and then see what happens to the linkage further up- stream.

It goes back I'm sure to day one cause Iv'e chased it a coiple of times with limited success.

May end up posting a request for linkage lengths of another pro head / SE front end owner

greyeagle
07-28-2008 06:32 PM
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

This is kinda silly

But, why isn't your pitch curve linear?

If you set it to -10, -5, 0, +5, +10 in NO time you'll get used to it and the heli will fly smoother than ever. If you need more pitch you can increase the ATV's to 110/110 120/120 and it will change it to something like -11, -5.5, 0, +5.5, +11.

Linear is the way. 0 pitch should be at 50%. The easy setup is leave all pitch curves "stock" meaning 0, inh, 50, inh, 100 and setup the bird mechanically to do this.

I'm pretty sure I've explained how to do this before, but someone it wasn't done due to fear of too much negative pitch at the lower stick level. In time (fairly quickly actually), you'll realize that its not so scary after all.

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
07-28-2008 08:16 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
Linear is the way. 0 pitch should be at 50%. The easy setup is leave all pitch curves "stock" meaning 0, inh, 50, inh, 100 and setup the bird mechanically to do this.

He can do that if he wants to. It would be better than what he has right now. But I suspect he has no desire to do all out 3D and knowing that he has only a 5 point radio he would be better getting all the resolution that he can get and not worry about hovering at the ¾ stick point. The fact is if you use a symmetrical linear curve your hover point will be where ever it wants to be based on headspeed. You also have no chance of softening the hover point if you hover at ¾ stick which is the fourth point on a five point curve.

I will let Grey deside what he wants to do before I make any further suggestions

Ace
What could be more fun?
07-28-2008 10:26 PM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

I agree both senerios are shaking hands -

Both samples have merit - and are very close to shaking hands on the symptoms and the agreement for solution. Easy kids let's solve this thing cause I have something WRONG period.

I know it's got to be a combination of my servo arm length and the mechanical resolution of the linkages. We have kicked this bucket and beat this horse since the day I converted the front end. I have been thru it several times. It's known as the Ra's / or Ray's Rule of 90- ing out your collective arm's at 0 / pitch at Zero and then go back and set total collective mechanical travel, then dial in what you need.

I'm going to tear into it again !

On this bird I have the old black style four point swash, " non -Fury".

I also have the very nice, hard to get, M/A Knurled, left hand and right hand threaded, rods going up to the head.

Going to check the collective servo ATV and arm to make sure it's centered at the 90 of travel which is buried inside the frame.

Ceter the 90 degree T - type tiller arm

Going to 90 out the arms going to the collective lift on the swash.

See if I can get total mechanical pitch +11 - 11

0 Pitch at mid range of the mechanical.

Either I got rods that are too long, or theirs a elevation difference between the old style swash and a fury swash.

Have yet to discover any rod lenght documentation on a SE conversion or running a pro head and a Older swash.

Please bear with me as it's more fustrating than you can imagine !



greyeagle
07-29-2008 01:39 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
Going to check the collective servo ATV and arm to make sure it's centered at the 90 of travel which is buried inside the frame.

Ceter the 90 degree T - type tiller arm

Going to 90 out the arms going to the collective lift on the swash.

See if I can get total mechanical pitch +11 - 11

0 Pitch at mid range of the mechanical.

OK you made your selection and that is fine with me so here are my suggestions:

1. Set your ATV’s to 100% right now. Don’t worry about being perfectly 90 at 0 degrees pitch until your full range of motion is set.
2. Because you will end up with 14 degrees of pitch motion (-5 to +9) aim for 20 (-10 to +10) instead of 22 degrees. You will set this by changing the length of the servo arm not by adjusting end points or ATV’s.
3. Once you have the total swing set you can then center or zero the arm at 90 degrees by rotating the servo arm one tooth at a time to get it close and use subtrim to make it bang on. Yeah I know, subtrim is a bad word for some people. Get over it.

Assumptions:
1. You took my suggestion and made your mechanical set up -10 to +10.
2. You still want -5 to +9 for your stick travel.
3. Your hover occurs at +5 degrees.

A soft hover curve will be 25, 65, 75, 85, 95 percent with the hover point occurring at midstick.

A straight line curve will be 25, 43, 60, 77, 95 percent or 25, INH, INH, INH, 95 with the hover point at almost ¾ stick.

BTW this mechanical setup will yield a 13% gain in resolution of the servos. Had you chose a biased mechanical set up of -5 to +9 you would gain an additional 30% in resolution. However, I am not familiar with this head design to know if this would create a can of worms for the cyclic. For the Predator it doesn’t create a problem.



Ace
What could be more fun?
07-29-2008 05:41 PM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Talk about a scarey resolution almost matches !!! the prediction !

Two nites and 6 hrs of wrenching here's the lastest -

By the way I discoverd a few other things - a few short shoulder - MA ball's where their should of been long shoulder ones. Found them on my 90 arms. " I didn't put them their, bout the only part I never touched !

I had every trick I know, from my inclonometer, line levals, swash lock, fly bar lock, Pitch guage, and pendulum protactor on this thing before I even started. Not to exclude my digital caliper.
Was able to achieve -10+10. Talk about chasing a linkage train- must of been up and down the complete line including swash 4 times
Good thing is that it tested by idle fail safe at 11 P.M.

I'll clean the bench later !

Here's the new ones and talk about being close to the new graph !
I'm not at homeplate completley - but Safe enough to test.

THANX a Bunch !!! I got fire up the printer

Pitch

1 35.5% -6
2 57.5% 0
3 72.5% +4
4 84% +9
5 95.5% +10


Throttle

1 = 8%
2 = 55%
3 = 67%
4 = 72%
5 = 95%

greyeagle
07-30-2008 02:50 AM
 
 
TooBizzy
Senior Heliman
Location: Georgetown, Ohio USA

55% throttle @ 0° pitch Might want to have a tach ready!

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...
07-30-2008 03:11 AM
 
 
GREYEAGLE
Key Veteran
Location: Sioux City IA

Good Point ! Thanx !

Yup we got one ! and glad you spotted it whew !

Latley I've been hovering right around 1680 and smooth.

I'll sneak up on it and be ready to dial here back. Thanx !

greyeagle
07-30-2008 03:38 AM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Your gaining …


Notice the right hand scale is your mechanical setup and the yellow left hand scale is what you created within your radio. I suspect that you did not set your ATV’s to 100% and then shorten you servo arms. That’s what is causing the crunching of the scale and where you loose some resolution.

Ok if you were to stay with this setup my only suggestion for softening the curve (yellow) would be to raise the second point to 62.5 and lower the fourth point to 80.5. You will also have to bring your throttle up and down respectively for these two points.

TooBizzy he had 60% throttle @0 pitch when he was flying this before! With the different carb and what he might have on the mechanical / radio setup of the throttle it is not alarming to me.

Ace
What could be more fun?
07-30-2008 09:12 PM
 
 
TooBizzy
Senior Heliman
Location: Georgetown, Ohio USA

Quote 
TooBizzy he had 60% throttle @0 pitch when he was flying this before! With the different carb and what he might have on the mechanical / radio setup of the throttle it is not alarming to me.

I hope you understand why that doesn't make sense to me when my Predator hovers (1650 HS) at 28% throttle and 0° collective is about 18-19% throttle (1650 HS). I've seen Raja post his curves on here before and his is within a few points of mine, so something doesn't sound right with Grey's setup....

I guess it's possible that if he has a lot of mechanical expo built in to his servo arm it would raise his throttle curves, but he hasn't posted that this is what he's doing. Could it possibly raise the T-curve to 60% @ 0° ??

P-Gasser Se, Raptor 50 Se Hyper, Raptor 30v2, Trex450se, 3dx450...
07-31-2008 03:34 AM
 
 
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Gasser Model RC Helicopters > Ever deviate from the pure linier pitch curve ??
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