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04-26-2014 05:34 PM  6 years ago
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mustang67ford

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Central Pennsylvania

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raptor 90 first run and questions
Was able to get the r90 gasser out today for the first time. I pre-set the needles to 1-1/2 for high and 1-3/8 on the low. Took the main blades off, and began to fill. This was my first problem. My fuel tank is set up with a 2nd clunk line going right to a fill/drain line. When I got it filled, because my fill line is down low, there was no way to stop the fuel from siphoning out before I got the plug back in. So:

1. Anybody know where I can get a fuel clamp that fits this fuel tubing? It is 1/4" OD/1/8" ID yellow stuff. I need to be able to shut the fuel off to get the plug in.

Maybe I should hange the fill/drain line to something more flexable like hayes black line or something. Ok, so now that I got fuel in it, I primed it and hit the starter (not using a pull starter) a couple times with the throttle closed. Opened the throttle to idle, hit the starter and it fired right up. Idled great, couldn't believe it and boy did it sound good. Let it idle briefly then shut it off and put the blades on. Fired right back up and I spooled it up. This time, I had a linear throttle curve, 0/25/50/75/100 and did see how it is different than a nitro. I reset the curve to 0/20/30/50/100. I know I was told my throttle curve should be 0/20/25/30/100, but the problem is, I typically hover at 75% stick meaning I would be at 30% throttle (100% on the curve = 100% carb open). If I give it a little more collective, now I will jup up to 100% throttle. So, question #2:

2. Do I really hover with 75% throttle stick and 30% on the throttle curve? just a little more stice will be quickly getting to 100% throttle.

Ok, so I decided to try to hover. Got it off the ground briefly, but the rudder would not hold. It wants to rotate clockwise; not instantly, but not slow either. I am using a GY520 with an align DS655 tail servo. I had the gain set to 50% in heading hold. My gyro is mounted on the tray above the boom behind the main shaft with 2 thick pads and the metal plate in between. I can't remember what setting I have it on in the gyro for the flight type. So question #3:

3. Anybody running this setup and what are your settings? Do I have enough gain and any advise on how to correct this?

All in all, it seemed to idle and spool up great, but was hesitant on hovering it. I also noticed, with a nitro, you can spool up and use the rudder to still turn while on the ground. The gasser is too heavy to do this with. It's in 1 piece so I consider it a success, but hopefully the next trip to the field will be better.
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04-26-2014 06:29 PM  6 years ago
jharkin

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Holliston, MA - USA

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1 If you can't find a clamp that works get a big pair of hemostats ( medical device, looks like a ratcheting needle nose pliers) I have one in my toolbox for just this purpose.

2 yes, you hover throttle will be that low. The butterfly plate throttle is very different from a nitro drum throttle like that, at 1/2 throttle if you look down the carb throat you will see that in terms of cross sectional area its almost wide open. Same as in you car..next time you drive consciously think about how much you press the gas pedal, I bet you don't push it more than 1/4 distance for 90% of your driving.

3 can't help much not a gyro expert. Have you tried turning up the gain a few points at a time till tail wag starts?
-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks
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04-26-2014 08:23 PM  6 years ago
Dappe Bronco

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Belgium

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For the gyro you probably need more gain. i would also try mounting the gyro on just a single pad in stead of the double you use now...
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04-26-2014 08:59 PM  6 years ago
mustang67ford

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Central Pennsylvania

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Hemostats is a good idea. So it is normal to be at 75% on the collective stick and at 30% on the curve with the next poin being 100%? I am just having trouble with that; going from 30 to 100 with only 1/4 stick.

I will try more gain on the gyro also. If i use only 1 pad, won't the vibration be worse?

Do you guys use any expo on the rudder to soften it? I have it set to none right now.
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04-27-2014 02:31 PM  6 years ago
jharkin

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I just copied my throttle curves from a local gasser expert this is with what I have:

Normal 0-20-25-30-100
ID1 100-35-26-25-100
-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks
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04-27-2014 02:39 PM  6 years ago
mustang67ford

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Ok, thanks. I will give that a try. Thinking out loud, does it even make sense to have a 100% throttle point, is it ever used?

I have another problem i think. When i checked my heli over, the rail servo (ds655) feels gritty or notchy. It is brand new. Now i need to see about exchaning it.
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04-27-2014 10:14 PM  6 years ago
RM3

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Killeen, Texas - USA

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does it even make sense to have a 100% throttle point, is it ever used
the answer to this is, it depends.

If you have physically set the throttle limits based on servo horn linkage...then yes...you would then got to 100% on your TX

But usually I try to stay away from actually going full WOT on the carb itself.

I have noticed on certin engines both modded and stock that WOT does not always mean max power...some engines actually drop in power a tiny bit at WOT.

now there is a way to get around this to some extent but its not perfect and thats with tuning the high needle....

but you have to remember that the high needle is not a perfect adjustment across the mid to high in terms of tuning performance...there is a compromise made between the mid range and high...so you basically have to find the sweet spot setting based on your helicopters pitch at that given RPM range to get the most from the engine at that point.
showing a preference will only get you into trouble, 90% of everything is crap...
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04-27-2014 10:23 PM  6 years ago
Lee O'Dell

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Gibsonville, North Carolina

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Gyro: Adjust TR linkage so you get no drift in Normal mode at somewhere around 50-60 % gain. Heading Hold mode doesn't engage until above 50% gain value... from memory. Been awhile since I used a reg Futaba gyro... but I am pretty sure GY 401, 601 and 520 setup is pretty much the same....keep flying it 'till the last part stops moving
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04-29-2014 12:14 AM  6 years ago
mustang67ford

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Central Pennsylvania

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I'll have to wait to try it again. Called align and i need to send them the tail servo.Team HeliProz - Retired
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04-29-2014 02:02 PM  6 years ago
BeltFedBrowning

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...
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05-09-2014 07:21 PM  6 years ago
mustang67ford

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Central Pennsylvania

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Got my replacement ds655 tail servo. Hope to get the heli back out this weekend. Lowered the throttle curve and took the gains up to 70%. Will see.Team HeliProz - Retired
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05-10-2014 10:07 PM  6 years ago
mustang67ford

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Got the gasser out today and hovered it for the first time. It seemed good so far with the revised throttle curve. regarding the gyro gain, at 75%, it would ossilate so once I got it back to 68%. In HH, it still wants to rotate clockwise, but in normal mode, I have it mechanically set and it holds solid.Team HeliProz - Retired
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05-13-2014 12:49 AM  6 years ago
mustang67ford

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Got some more flights in over the weekend, basically just hovering around. I noticed the heli seems to wobble some in the air even thought the tracking is great. I increased the throttle curve some; now at 35%. I am thinking if the head speed were a little higher it would smooth out some. Increasing the throttle curve some didn't seem to work. I am wondering that once the motor is broken in and i can lean it out some, if i'll get better performance. Also, how do i check the motor to see if it is runnig too hot?Team HeliProz - Retired
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