Throttle curve characteristics fixed wing IC

[Ron Gray]

20 minutes ago, john stones 1 - Moderator said:

I thought we encouraged people on here ?

Don’t know where that came from, can’t see that anyone is really ‘dissing’ F3A or non F3A (well apart from me querying why advanced electronic aids are now allowed). Mountains out of molehills springs to mind.

 

@Graham Bowersgreat to see that you’re getting more enjoyment from your flying having dipped your toe into ‘F3A’ . I did the same a few years ago but didn’t continue with it and feel that it helped improve my non F3A flying!

[Graham Bowers]

12 minutes ago, Ron Gray said:

Don’t know where that came from, can’t see that anyone is really ‘dissing’ F3A or non F3A (well apart from me querying why advanced electronic aids are now allowed). Mountains out of molehills springs to mind.

 

@Graham Bowersgreat to see that you’re getting more enjoyment from your flying having dipped your toe into ‘F3A’ . I did the same a few years ago but didn’t continue with it and feel that it helped improve my non F3A flying!

Thanks @Ron Gray. I can't agree more about the positive effect on other aspects of flying - ultimately all flight is about negotiating 3D space, it's just the outcomes sought that differ. Before doing this the only thing that stopped me putting my left hand in my pocket was I'd have dropped my transmitter* 😉 (Well, not quite that bad, however I'm sure the gist is clear).

 

*Mode II.

[Jon H]

Thanks for the background Graham, things make more sense now. 

 

Personally i would still not bother with a curve, but then again i base that upon the way i set up my own throttles mechanically as they give me a nice smooth and predictable power delivery doing it the way i do. How this compares to the setup others use i dont know so perhaps i just do it in such a way that there is no advantage? Not sure. Certainly i have never felt the need to add it as i have all the throttle control i need. 

 

As i already mentioned I applaud your efforts to improve your flying and aero's of any kind can be very good as a tool for learning a variety of techniques. I came at it from the other direction as i found my scale flying helped my aerobatic flying as i would tend to just wring the neck of my aerobatic models when i was young but warbirds taught me a little more patience and finesse! 

 

As a curiosity, what do we even mean by aerobatics? I can fly aerobatics with my Stampe, but they arent the same as the ones i fly with my WWII stuff, my AWXL or my spacewalker. I fly all them precisely, within the limits of the aircraft i am flying, but they arent precision aerobatics in the same way as an f3a setup is intended to be flown. Not all aerobatics are the same or require the same model set up. 

 

But i guess that is enough chat, time for some flying i think. My AWXL has not flown in more than 6 months, the engine needs a run and i need some practice as i felt rusty as an old nail flying yesterday. 

[Graham Bowers]

8 minutes ago, Jon - Laser Engines said:

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As a curiosity, what do we even mean by aerobatics?

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It is Precision Aerobatics I'm attempting to learn.

[Philip Lewis 3]

3 hours ago, Ron Gray said:

You’ve done a really good job in explaining it, many thanks. So it’s not like cruise control in a car which maintains your speed.

Cruise control is a perfect comparrison, that is what it does, however, a car has a perfect grip on the road so for every turn of the wheels it moves the circumfrance of the wheel forward which would also be true if the propeller had a perfect grip on the air, but it doesn't, a propeller suffers slippage and the harder the force it is trying to overcome (draggy airframe or gravity being two examples) the more slippage you get.

 

By way of the only (poor) example I can think of, it's an icy road, the grip of the tyres is however enough to maintain speed when the road is level but now it encounters a one in three hill, there is some grip but the wheels start to  lose traction and partially (spin), the wheels are still going the same speed but the car isn't and if the hill gets even steeper then at some point may actually come to a stop or even start moving backwards but the wheels are still going the same speed.

 

I hope that makes some sense?

[Matt Carlton]

On 08/04/2023 at 11:59, Philip Lewis 3 said:

propeller suffers slippage and the harder the force it is trying to overcome (draggy airframe or gravity being two examples) the more slippage you get.

 

That's true for a model sitting still, but the amount of slip varies with airspeed. Consequently, thrust is not equal throughtout the flight, even if the throttle isn't touched. Indeed, it is perfectly possible to exceed the net pitch speed and have a resultant thrust of zero. Therefore, whilst throttle curves etc can help create a more linear throttle response, that doesn't necessarily mean that the airspeed or thrust response is also linear.

At best, the throttle curve will be right in one area of the flight envelope, so for my dumb thumbs and creaky models, I make do with wiggling my thumb around to get the response I want from the model.