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Thread: When to throttle back? Reply to Thread

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[QUOTE=Billpilotca;1893985]Rick - sorry to frustrate you. This becomes a bit complicated but let's just say there are two related goals here.  Firstly to have the optimal throttle level to fly straight wind corrected lines (horizontal, vertical, 45 degree), and to fly the various elements within the maneuver (roll, point roll, snap etc), but also to manage "sound" and keep it down!!

I am glad you fly mostly at half throttle.  80% of the pilots in any club probably don't know what mid-throttle is.  That is likely overstating reality for effect, but when I watch pilots fly in my own club they tend to have two speeds - full bore and throttle back for landing.

Throttle management does not need to be perfectly linear.  I have an intentional flat spot programmed into my throttle curve so I can find a nice cruising speed as I fly the maneuvers.  I am aiming for a spectrum between full throttle - cruising speed - low throttle and idle.  I just try to effectively use the throttle spectrum to optimally present the geometry of the maneuvers.

Also throttle management in relation to sound is important in IMAC because it is a "judged criteria".  Pilots are assigned a "sound score" as part of the overall scoring of the flight.

Ripping the prop is not a positive thing in IMAC flying and we need to manage the left stick and match the prop to the engine to give us the necessary thrust but without creating supersonic speeds at the prop tips that causes the ripping noise.  A low sound score could lose you the contest.

Lots to talk about .....[/QUOTE]

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09-13-2014 08:44 PM

-Rick-

Re: When to throttle back?

Kinda funny, when I was flying nitro, I liked full bore. When I got into the gas planes I like to see them flying on the wings, not the motor.

The flat spot in your curve helps me understand. As you say, much to talk about and in my case, much to learn!

09-13-2014 08:17 PM

Billpilotca

Re: When to throttle back?

Quote:

Originally Posted by -Rick-

And that right there is something I totally do NOT understand! I generally fly at half throttle, very, very rarely do I go full. But I do use the throttle very much. I really can't understand how a setting on the throttle could make a difference. To make a throttle have a linear curve is beyond my understanding sorry to say. And why it is necessary.

Rick - sorry to frustrate you. This becomes a bit complicated but let's just say there are two related goals here. Firstly to have the optimal throttle level to fly straight wind corrected lines (horizontal, vertical, 45 degree), and to fly the various elements within the maneuver (roll, point roll, snap etc), but also to manage "sound" and keep it down!!

I am glad you fly mostly at half throttle. 80% of the pilots in any club probably don't know what mid-throttle is. That is likely overstating reality for effect, but when I watch pilots fly in my own club they tend to have two speeds - full bore and throttle back for landing.

Throttle management does not need to be perfectly linear. I have an intentional flat spot programmed into my throttle curve so I can find a nice cruising speed as I fly the maneuvers. I am aiming for a spectrum between full throttle - cruising speed - low throttle and idle. I just try to effectively use the throttle spectrum to optimally present the geometry of the maneuvers.

Also throttle management in relation to sound is important in IMAC because it is a "judged criteria". Pilots are assigned a "sound score" as part of the overall scoring of the flight.

Ripping the prop is not a positive thing in IMAC flying and we need to manage the left stick and match the prop to the engine to give us the necessary thrust but without creating supersonic speeds at the prop tips that causes the ripping noise. A low sound score could lose you the contest.

Lots to talk about .....

09-13-2014 07:37 PM

-Rick-

Re: When to throttle back?

Quote:

Originally Posted by Billpilotca

Throttle management got hammered into me early in my IMAC experience. Some guys have two speeds, full throttle and idle. You need to work the range in between especially finding a cruise speed between maneuvers. Just keep at it and it will get better.

Usually gas engines don't have a linear throttle curve. You might want to try 30-35% exponential on the throttle and that may give you a more linear feel. Higher end radios let you set points in the throttle curve. Give it a try and fix it if it does not feel right (more or less expo).

09-13-2014 07:30 PM

Billpilotca

Re: When to throttle back?

Quote:

Originally Posted by -Rick-

That is exactly what I am doing, coming over the top, in a near stall, having the wings "flop" around and losing my line for the 45. And keeping zero throttle on the way down...

If your plane does not have unlimited vertical, you will likely have to judge at what point the plane is slowing down and you need to start to pull into the radius for the 45 downline. You want to avoid the stall at the top and have enough momentum to carry you into the 45 downline and then maintain enough low throttle to keep the line straight. Practice, practice ... burn gas or electrons

09-13-2014 07:25 PM

Billpilotca

Re: When to throttle back?

Quote:

Originally Posted by thegr8david

This was an excellent question Rick, it has given me something to digest. Sounds like I have to work on my throttle control some more.
Thanks for the pointers guys.
Dave

09-13-2014 07:07 PM

-Rick-

Re: When to throttle back?

"The tendency is to back off too far on throttle and then you end up with a "sagging" 45 downline". You need a bit of "juice" to hold that line as you do the half roll back to upright."

That is exactly what I am doing, coming over the top, in a near stall, having the wings "flop" around and losing my line for the 45. And keeping zero throttle on the way down...

09-13-2014 06:28 PM

thegr8david

Re: When to throttle back?

This was an excellent question Rick, it has given me something to digest. Sounds like I have to work on my throttle control some more.
Thanks for the pointers guys.
Dave

09-13-2014 08:19 AM

Billpilotca

Re: When to throttle back?

Quote:

Originally Posted by -Rick-

I am talking of the shark tooth maneuver where I have most of my problems. I worry that if I come over the top to fast it sets me up coming down on the 45 degree to fast and it doesn't look right.

Rick - as I am sure you know it basically becomes a practice and "feel" thing. Just go out and fly the Shark's tooth for the whole flight and try it at different throttle settings. All planes and throttle curves are different so all you can do is practice it until it is right. You can do them at both ends so you are practicing both directions and just fly Sharks for the whole flight.

A regular Shark starts vertical up so you are likely going to be at full throttle on the upline. As you come to the top you keep the power on as you pull a nice radius to the 45 degree downline. Just work on it at different throttle settings with a bias towards more throttle than less. As you work the plane into the 45 downline you will be throttling back but not all the way to idle. Keep a bit of power on and try and draw a straight line.

The tendency is to back off too far on throttle and then you end up with a "sagging" 45 downline". You need a bit of "juice" to hold that line as you do the half roll back to upright.

Practice, practice, practice ...... and have fun

09-12-2014 11:56 PM

-Rick-

Re: When to throttle back?

Quote:

Originally Posted by itizme

I'd like to add to Bill's great advice. as you do come over the top be sure to ignore sound, you should hear the engine at full or partial throttle as you are entering the down line because of the distance. 100% visual, next year I am going to practice and this will be one of the things I am failing at in the past and not the future.

I should add, as Bill and Brent know that I'm just a beginner in IMAC. I am flying basic with a 30cc pilot Edge 540.

The above could be a big part of my problem, I'm waiting to hear the motor throttle back and maybe by the time I hear it I have lost so much forward momentum that I am almost in a stall situation as I come over.

I am talking of the shark tooth maneuver where I have most of my problems. I worry that if I come over the top to fast it sets me up coming down on the 45 degree to fast and it doesn't look right.

09-12-2014 09:05 AM

goneflyin

Re: When to throttle back?

The way I like to look at it is, you want to maintain a constant airspeed throughout the entire sequence. Uplines, downlines, horizontal etc, all thru the flight, the same airspeed. So use whatever throttle settings you need to accomplish this.
For example, thru a simple loop, you'd be starting from horizontal at midthrottle, and increase throttle to full for the climb, slowly taper off the power over the top, idle for the dive, slowly increase again as approaching the bottom and back to horizontal.
Imagine if there was an airspeed indicator on your transmitter, the needle would not move throughout the maneuver.
This method should make the flight controls have a constant feel/response thru all maneuvers, especially important when it comes to more complex snaprolls etc.

Don

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