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Helicopter
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Blade
Other › insufficient lift problem
12-03-2005 04:29 PM  12 years agoPost 1
jonellison13

rrNovice

Charlotte, NC - USA

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I'm a new CP owner and after a couple weeks of practice and crashes, I'm finally hovering... now I've got a problem I just can't seem to figure out. After a recent re-build, the heli's lift is not responding correctly. Previously, heli was becoming "light on the skids" at 50% throttle and really taking off at 70-80%! Now, I'm at 80% at liftoff, and when I push even harder to 90-100% the motor sounds like it's bogging down, and the heli loses altitude. The pitch on the rotors is set to start at about 2 degrees and push to 12 degrees (no pitch gauge, just guessing). They are set a little higher than factory because at the factory settings, I can't even get off the ground at full throttle. The ENTIRE head including paddles and rotors appear to be in perfect alignment (as much as plastic parts will allow) and well lubricated with a synthetic bearing grease. My only guess would be the main motor, but it just doesn't seem like I could've worn it out so quickly. Any Ideas? (p.s. yes, all batteries are in good condition with proper output.) Thank you guys for the support!!!

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12-03-2005 04:38 PM  12 years agoPost 2
slider46

rrProfessor

Ocala Florida

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Sounds like you need to buy a pitch guage and find out exactly what pitch you have now. Then you can make the proper adjustments to the pitch so the heli will fly correctly... You can't set the pitch by eye and be accurate enough for a good flying heli.....

Tom..... No "D" flying....

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12-03-2005 04:49 PM  12 years agoPost 3
bwarkent

rrApprentice

Houston Tx

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Pitch gauge is pretty much a necessity. Verify that the pitch curve matches the one in the manual, 0 at 0 stick and 5.5 at half stick. Next take a look at blade tracking. If it is off significantly this will absolutely kill lift! I put a set of unbalanced night blades on a brushless helicopter and got very little lift out of them. If the blades are dinged up, rebalance them or replace.

This assumes that the feathering shaft is not bent. Also verify that one of your pitch arm links has not popped off towards the inside of the ball thus changing the pitch of one of the blades.

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12-03-2005 05:31 PM  12 years agoPost 4
Wa11banger

rrElite Veteran

Huntsville, Al

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One of the best ways I have found to reset the heli after a tear down is to unplug both the main and tail motors and turn it on.. Set the switch in Idle up, put the throttle at center stick and adjust the blades until they are zero degrees at center. Done.. Now when you take it out of throttle up the built in mixing will be back to normal plus you will have equal travel positive and negative in throttle up. The heli flys very well this way.

Just my .02
Rick

Proud member of the Quick UK, Duralite Flight Systems, V-Blade, & KBDD team

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12-03-2005 06:10 PM  12 years agoPost 5
BikeNBoatN

rrVeteran

Santa Ana, CA USA

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Make sure the covering material on your rotor blades is not torn or flapping anywhere. If it is, it will kill lift and you'll never get off the ground. I use a little CA to glue it down and wrap my fingers in a plastic bag so I can press the covering down without sticking to everything.

Otherwise, check the threads for sticky collective fix. There's two parts: the main blade grips mod and the rotor hub/spindle have to slide up/down absolutely freely with no binding. If you crashed recently, my guess is that the hub is binding somewhere on the spindle. Often times the flybar will bend around and cause gouges on the spindle shaft where the slot is.

Replacing the 0.039" steel shear pin with 0.032" brass rod will allow the shear pin to actually shear during crashes. This saves a lot of parts from damage. Also prevents the shear pin hole in the main shaft from becoming egg-shaped.

Brent.

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12-04-2005 12:00 AM  12 years agoPost 6
jonellison13

rrNovice

Charlotte, NC - USA

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Some additional questions

Well, this brings up a couple additional questions I have:

The general concensus (including the manual) shows that the pitch on the main rotors should travel from 0-10 degrees (or -10 - 10 in idle up mode). Does anyone have any experience with a pitch greater than 10 degrees at 100% throttle... i.e. does the pitch of the rotor actually start to defeat the lift(ing) of the rotor?

Second question in response to BikeNBoatN's post... if the shear pin in the head of the main gear has bent and worn out the hole through the shaft, effectively giving it that dreadfull egg-shaped likeness (and enough slop to feed a herd of pigs), is that going to effect the lift of the heli? I would think it would only contribute to sloppy throttle changes, but I really can't wager much more than a guess.

Thank you guys for responding so quickly!

"how much can you know about yourself if you've never been in a fight?"

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12-04-2005 12:45 AM  12 years agoPost 7
c mark smith

rrApprentice

Mt Vernon, Indiana

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A loose drive pin won't be noticed until it fails completely.

The drag of the rotor and the torque of the motor will always keep it loaded in one diretcion only.

A blade that has way too much pitch will be stalled, with a tremendous amount of drag and a redyced lift. This will likely slow the motor substantialy,,,,,,,

Adding a bunch of extra weight, such as heavy lipos, swash and othert parts of aluminum, brushless motors, extar ESC's, etc, may require more lift than the blades can produce without more RPM than the motor can provuide. Longer vlades and a tooth les on the drive pinion may be the only solution.

Stock is best,,,,,,,,,,,,,,,,,,,,,,,,

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12-12-2005 02:45 PM  12 years agoPost 8
jonellison13

rrNovice

Charlotte, NC - USA

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still insufficient lift!!!

Well, I've taken the blade apart... rebuilt the head (with new parts) checked for binding... checks okay... checked for binding at ALL friction points... checks okay... replaced the main motor (on advice from horizon hobby), installed heat sink... leveled swashplate, new rotor blades, leveled rotors, tracked rotors, set pitch to zero... lightly oiled all friction points... still only minimal lift at 75% and a bogged down sound and even less lift at 100%. I put a voltage meter on the main rotor plug (without motor plugged in, but with rear motor plugged in) got 10.7 Volts at 50% throttle and 10.3 Volts at 100% throttle. WHATS HAPPENING!!! ITS DRIVING ME CRAZY!!!

"how much can you know about yourself if you've never been in a fight?"

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12-12-2005 03:55 PM  12 years agoPost 9
nuts4rc

rrNovice

Vancouver, Wa USA

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One thing I ran into on a rebuild is that somehow I messed up the length of the swash links to the servos and when the swash would travel downward it would actually cause binding making the servos work harder and drawing more power. I noticed this when the sliding portion of the head was not centered between the top and bottom of the center hub and spindle while at zero throttle and trim it was actually lower which made it closer to the bottom of the center hub and would actually hit the bottom before full power. The other thing that I had issues with was the blade tracking and whne I made the adjustments noted in the manual I had much more lift and stability. The final thing I have had happen is that the flybar paddles were not at 0 degrees when compared to the paddle control frame. Good luck and I hope this helps.

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12-12-2005 04:28 PM  12 years agoPost 10
bwarkent

rrApprentice

Houston Tx

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Which head parts did you replace? Did you use a pitch gauge to measure your blade angles? What is your measurement at half stick in normal mode?

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12-12-2005 04:31 PM  12 years agoPost 11
Awais

rrApprentice

Mississauga, Ontario - Canada

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I put a voltage meter on the main rotor plug (without motor plugged in, but with rear motor plugged in) got 10.7 Volts at 50% throttle and 10.3 Volts at 100% throttle.
That sounds about right to me. Your servos are working harder at 100% throttle comparing to only 50% throttle. So thats why the voltage on the battery is dropping under load. Someone correct me if I'm wrong.

Did you check how much pitch you get at full throttle? Could it be the main shaft bearings worn out causing the drag/friction. Take off the main blades and spin up, see if the motor bogs down. It shouldn't too much.

Awais

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12-12-2005 04:42 PM  12 years agoPost 12
saahbs

rrApprentice

Aurora, IL.

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Awais,

I don't think servos could account for that much drop unless all of them are _binding_. What I think is happening, is increased current (I) at 100% throttle causing the battery pack voltage to drop due to it's internal resistance. Quite normal and healthy behaviour.

Mike

--
I fly airplanes, sailplanes, helis; nitro and electric.

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12-12-2005 05:00 PM  12 years agoPost 13
Awais

rrApprentice

Mississauga, Ontario - Canada

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saahbs,

I thought of that, he said the motor wasn't hooked up. Even if the throttle was increased, it really didnt have any load on it, so the voltage shouldn't drop. Although he did mention he had the tail motor plugged in (just re-read the post). If he can try checking the voltage with the tail motor unhooked, that might explain it.

Awais

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12-12-2005 05:34 PM  12 years agoPost 14
jonellison13

rrNovice

Charlotte, NC - USA

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voltage without the rear motor plugged in is as follows:
0-50% throttle 10.7V
50-60% throttle 10.6V
60-80% throttle 10.5V
80-100% throttle 10.4V

The Pitch is set as near 0 degrees as possible (at 0% throttle or 50% throttle in idle up). I cannot find any binding anywhere including bearing sets in main shaft. I can't imagine the 4-in-1 would cause this problem. Next chance I get, I'll remove the main rotors and spin it up... this won't burn out my main motor will it? (well, I guess I have an extra one now anyway... grrrrr.)

thanks guys and gals...

"how much can you know about yourself if you've never been in a fight?"

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12-12-2005 06:37 PM  12 years agoPost 15
bwarkent

rrApprentice

Houston Tx

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If you are using the stock transmitter then hovering will happen at half stick. You should see 5 degrees at half stick. Get a pitch gauge and measure it on both blades at half stick. Don't forget that the flybar has to be level. If your pitch measurement is off by two or three degrees(which by eye it very well could be) then this could be the difference between hovering and not.

Did you replace the feathering shaft? If it wasn't replaced then check it on a piece of glass. If it is bent then the blades may appear to be in track at one pitch and then go out of track when the pitch changes.

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12-12-2005 06:57 PM  12 years agoPost 16
c mark smith

rrApprentice

Mt Vernon, Indiana

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If you have the flat bottomed blades, they will create lift even with a zero angle of attack.

Symetrical blades will produce no lift at zero.


I tried some symetrical and had to increase the static angle/pitch

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12-12-2005 07:17 PM  12 years agoPost 17
jonellison13

rrNovice

Charlotte, NC - USA

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well, I did eyeball the pitch in, and experimented with the pitch arms by a half turn three steps in both directions. I took the rotor blade off and spun up the heli and didn't get any binding even at full throttle. I also went to put the volt meter on the main motor to measure voltage, but it interfered with the 4-in-1 and started going crazy... i wouldn't recommend anyone doing that (just about got a rotor to the face). I'm stumped... when the rotors go back on, I get the same bogging down noise and lose lift at 90-100% throttle and liftoff is still at 65-70% throttle. Its crazy man... maybe I'll rebuild the head again...

"how much can you know about yourself if you've never been in a fight?"

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12-12-2005 07:21 PM  12 years agoPost 18
Awais

rrApprentice

Mississauga, Ontario - Canada

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Are your blades balanced (ie. center of gravity of both blades is the same and they both weigh the same). Make sure the plastic protective covering on the blades is intact cuz it could cause drag. If its ripped off from somewhere put some tape on it and balance the other blade by putting the same amount of tape at the same location.

Also did you notice any vibration in the heli with and without the main blades?

Awais

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12-12-2005 08:45 PM  12 years agoPost 19
midwestpilot

rrElite Veteran

Crystal Lake, IL

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You need to consider...

the 4 in 1 is toast...
Crashing with power on can cause an amp surge to the 4 in 1...

If you can find a buddy with a blade...swap out 4 in 1's and see what happens...

In life there is no spacebar!

Rich Erikson AMA 6175

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12-12-2005 10:46 PM  12 years agoPost 20
jonellison13

rrNovice

Charlotte, NC - USA

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I surrender!

Unless you guys can think of any other possibilities, I think I'm going to wave the white flag and send it in to Horizon. Spoke with product support and exhasted those resources... its probably something I'm completely missing like having the rotors on backwards or I used the wrong diameter lead pipe on the skids... ARRGGG! (I really think the 4-in-1 is acting up... and I hesitate to be the guy that just blames the electronics I don't understand... i.e. "the hard drive is broke. - "that's not a hard drive. - "oh".

"how much can you know about yourself if you've never been in a fight?"

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Helicopter
e-
Blade
Other › insufficient lift problem
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