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Thunder Power RC ProModeler
motorrc

Senior Heliman

canton ohio usa

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I have a 46 v1 raptor that is bogging down on rolls. My pitch is -11 and +11 It has plenty of power on full power climb outs. My throttle curve is 90 77 62 77 90 on stunt 1 and 95 88 77 88 95 on stunt 2. There is no difference in performance in terms of bogging down between stunt one and two. I am using 550mm carbon 3D blades. My aileron throttle mixing is 25 percent. I am running 30 percent nitro. I have confirmed that the throttle is all the way open when the stick in all the way down in stunt 1 and 2. I don't think changing paddles would make a difference since there is plenty of power when the heli is upright and so it should have the same amount of power when inverted. Not sure where to go from here.

if it doesn't fit, make it fit.

07-03-2016 01:44 AM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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My guess would be that you are adding too much negative pitch during the inverted portion of the roll ....

Been there, done that and old enough to know better.....

07-03-2016 02:12 AM
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utahbob

Senior Heliman

St. George Utah

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I think AZ jr. coined the term..

Collective management

I do a great decending funnel!

07-03-2016 03:20 AM
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Cowjock

Veteran

Pa.

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^+1

Damn that ground is hard! When's the right time to get out of this money sucking hobby?

07-03-2016 03:28 AM
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Magnumeng

Veteran

29 Stumps, CA

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One thing i use to do on my little 30's was program mix in a little extra throttle with elevator and aileron stick movements... Think it was like 10%

TDR, Kontronik Kosmik Cool 200, Kontronik 750-56, CGY750,
Team KBDD

07-03-2016 05:58 AM
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Jeff polisena

Elite Veteran

westpalmbeachflorida usa

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When your rolling your adding pitch and overloading motor . You can change paddles and lower cyclic and it will help .

I stole it ,flew it and gave it back ;)

07-03-2016 03:42 PM
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oldfart

rrProfessor

Vancouver, Canada

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First you say that the top and bottom of stunt 1 throttle curve is 90, and those of your stunt 2 is 95. You also state that you checked and found the throttle barrel opens fully when the stick is at the top and bottom in each mode. If all a is set properly, then if a 95 setting does so, then the 90 setting would not be able to do so. I would certainly check that out.

Next, with the throttle at 1/2 stick on the bench, verify that when you do give an aileron or elevator input that you mixing does indeed open the throttle more and does not throttle lower instead. If it lowers it, then use the opposite mix numbers then you are using now.

Then add as much % of mix you need to keep it from bogging. In low power set-ups (OS32F in 30 Heli with 550 blades) in the past I have used as much as 100%.

Phil

07-04-2016 04:54 AM
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Richardmid1

rrProfessor

Leeds, England

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First check what Oldfart said. How quickly is it rolling? You could try lighter paddles so it rolls quicker at lower cyclic pitch. Also use very little negative pitch as it rolls over.

60% of the time, it works every time!

07-04-2016 11:35 AM
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Jeff polisena

Elite Veteran

westpalmbeachflorida usa

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When not using a throttle control device you will have a lag . Throttle curves are limited on precision . If you set curve for rolls and flips then it will seem to over rev on transitions or at hovers . You can get close with settings using different flight modes but will feel like your switching a lot . If this is something you want to keep look into a control device .
Throttle jockey makes a simple , small unit that will help with keeping consistent rpms.

When you load head using just curves you have no correction but with a gov/limit device it corrects as needed making better power ahead of load .

I stole it ,flew it and gave it back ;)

07-04-2016 01:10 PM
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Richardmid1

rrProfessor

Leeds, England

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You could also be running too rich. 77% throttle at mid stick should be screaming! When I used curves I found 50-60% was needed at mid stick to avoid over speeding.

60% of the time, it works every time!

07-04-2016 01:19 PM
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motorrc

Senior Heliman

canton ohio usa

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Thanks to everyone for the comments and help.
Throttle moves as it should when aileron or elevator inputs are given.
Doubt that I'm running too rich-back plate is hot using the 5 second test. Dialed negative pitch down to 9 degrees-plan to fly today to assess. To me, whatever is wrong should address just the inverted phase of flight, since it has plenty of power on full power climb outs and forward flight-that why I'm avoiding changing things that would effect regular forward flight like changing carburetor settings. I'll post results of test flight.

if it doesn't fit, make it fit.

07-04-2016 03:03 PM
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JuanRodriguez

Elite Veteran

The Villages, Florida

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Yes, it's a good idea to only change one thing at a time....

However, I would not change any of your setups just yet..... specially that 9 degrees of pitch thing you're planning on doing....

Go back to the initial suggestions in this thread....

I mentioned that you are probably adding too much pitch during the inverted portion of your rolls......

Next post after that is "collective management"...... which is exactly the same suggestion I gave......

Without making any changes, simply fly your model, get it into ff speed INTO the wind and SLIGHTLY pull your nose up just prior to commencing with the roll.....

Now, as the model rolls inverted, here is where your problem most likely lies...... When inverted, reduce your collective stick ONLY HALF WAY to approximately mid stick......

If you bang the stick all or most of the way down while inverted in your roll, you are going to bog the motor and the roll is going to look really ugly !!

The whole thing boils down to "technique" (collective management)

When I do my rolls, I can do three consecutive rolls before aborting to make my turn upwind.......

I do, however , use a governor but the technique as above would be the same.....

Been there, done that and old enough to know better.....

07-04-2016 03:56 PM
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Richardmid1

rrProfessor

Leeds, England

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...don't go by finger on back plate method when tuning an engine.

60% of the time, it works every time!

07-04-2016 05:41 PM
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oldfart

rrProfessor

Vancouver, Canada

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Relative to lean or rich while inverted: Note where the center line of your fuel tank is relative to your carbs needle valve when right side up, I would bet it is about 1/4" or so BELOW the needle valve. Then note where it is when inverted. I would bet it is now 1/4" or so ABOVE the needle valve. A higher tank will always run an engine richer then a lower one.

That said, during a single roll or loop, with proper collective management as mentioned by Juan, (with your stick only coming to half during the rather brief inverted section) and your needles are set correctly, there will be a difference in good to rich, but not enough to bog the engine - specially a 46 turning 550mm blades at even as high as a 2000 rotor speed.

If your roll rate is too slow, and you are using muffler pressure, then some installations can result in raw fuel feeding from the tank, through the pressure line into the muffler. Some of this raw fuel can, in turn, be sucked into the engine and cause a rich setting for a brief time.

Richard alluded to your throttle curve settings. Your S1 is 90/77/62/77/90. I must agree with him. If the idle/mid and main needles on your 46 are set properly, 62% would be a very high setting. As you would go through mid stick (0 pitch) you would definitely experience some increases in rotor speed.

Do you know what head speed you are turning or would like to turn?

Of course, as Juan and Jeff said, a governor is always a good way to help keep a constant head speed but they also will not work as advertised, if the engine is not tuned properly

For a basic understanding of how all of this relates, you may find these two articles of interest.

http://www.leisuretech.ca/index.php...rottle_-_pitch/

http://www.leisuretech.ca/index.php.../faster_cyclic/

Phil

07-04-2016 07:05 PM
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motorrc

Senior Heliman

canton ohio usa

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This is just a follow up as to what happened at the flying field today. I decided not the change the negative pitch setting to 9 (left it at 11) and from what was said earlier, when doing a roll and going inverted, just trying to stay at perhaps 2 or 3 degrees of negative pitch instead of bagging it down all the way as I was doing and getting 11 degrees negative. This definitely made a big difference in not bogging down the motor. The only bad thing now was the heli dropped some altitude in the maneuver. A more experienced pilot than me used the term collective management and felt that the drop in altitude was just a function of timing.(as in bad timing on moving the pitch stick) As a final test, he flew the heli and hovered it inverted with no problem (I was not sure it had enough power to hover inverted).He felt, and I get the feeling so do most of you, that the motor bogged on rolls because I was putting 9 degrees of aileron to roll and then adding 11 degrees of pitch was just too much for the engine to handle. So the summarize, it seems the problem is mostly with me at this point rather than with the machine.

I was a little surprised that the 5 second back plate test was frowned upon when trying to see if the machine is running too rich (back plate cool) or lean ( back plate hot) What in your opinion is a more reliable way to tell?

As far as head speed, I think 1800 would be good. I don't know what my headspeed is, but I do have an optical tachometer-I plan to check on my first opportunity.

if it doesn't fit, make it fit.

07-04-2016 09:30 PM
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Richardmid1

rrProfessor

Leeds, England

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Checking the back plate isn't very reliable as not everyone has the same sensitivity in their finger ends, the back plate will heat up after landing so it depends how quickly you check it, air temp and altitude will determine how the engine is tuned (richer or leaner) therefore engine temps between me flying in the UK at 10C and you flying in the US at 25-30C for example will be very different. Your back plate should be much hotter than mine.

The best way to tune is to go by sound and power and lastly the smoke trail but that can vary also.

P.S. try 1900 instead of 1800, it will roll quicker meaning you don't need to be as precise with the timing of the collective.

60% of the time, it works every time!

07-07-2016 11:48 AM
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