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Author Topic: Modern stabilisation and free-flight  (Read 1030 times)
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3view
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« on: March 06, 2018, 12:04:48 PM »

https://vimeo.com/258823020

I've finally got some video of my low-wing test model.  It has wing-levelling by using a R/C stabiliser on the ailerons only.

Steve
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Modern stabilisation and free-flight
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BG
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Me with F1B - epic retrieval (flew 10km after DT)


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« Reply #1 on: March 06, 2018, 12:23:49 PM »

interesting idea. Could you elaborate on the system you are using?
thx
B
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F1B guy but its not my fault, Tony made me do it.
3view
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« Reply #2 on: March 06, 2018, 12:46:15 PM »

The Flight stabliser used is an Eagletree Guardian, however this stabiliser still needs R/C type inputs (sticks centred) to work for free flight.  These inputs are provided by some electronics of my manufacture.

Steve

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PeeTee
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« Reply #3 on: March 06, 2018, 01:59:29 PM »

Steve

Is this like your system for your jets?

Peter
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3view
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« Reply #4 on: March 06, 2018, 04:38:36 PM »

https://vimeo.com/24019743

Peter,

I've only ever used a mechanical pendulum on a FJ-4, see above.  Pendulum ailerons worked well on this model but the sweptback wing must have helped a lot.

Steve
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« Reply #5 on: March 08, 2018, 05:41:23 AM »

https://vimeo.com/245742661

The above link shows 3-axes stabilisation using this system, however this is now entering drone rather than free-flight territory?  So I see the natural home for stabilisation is on a large scale model that needs help with lateral stability (wing levellng)

There is a full description of how the system works in the latest (March 18) Aeromodeller.

PM me if you are interested.

Steve
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« Reply #6 on: March 19, 2018, 02:16:44 PM »

For free-flight scale competition I would like to see modern stabilisation allowed, however, with a negative bonus system in place.

Something like this..............

1 axis stabilised ............ -15% flight score deducted
2 axes stabilised ...........  -30%
3 axes stabilised...........  -45%

K factors remain unchanged.............. simple!

What are your thoughts?


Steve 
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billdennis747
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« Reply #7 on: March 19, 2018, 03:36:02 PM »

Hi Steve,
As you know, the Scale Tech Committee (to which I am loosely attached as outdoor FF rep) have briefly discussed this and decided to do nothing yet and see what happens. It's tricky - it's really just an extension of pendulums, but it works.
My personal view is that one axis only (lateral) should be allowed. Most models can be trimmed in the other axes so that's down to trimming skill, but as you have found, something like a Hurricane with scale dihedral just will not work. I'm not sure a negative bonus is necessary and I would resist adding anything to the rules, which are nice and simple.
Bill
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« Reply #8 on: March 19, 2018, 05:51:04 PM »

Steve/Bill

We have the same issue with motor flight profilers on electric models for starting, power phase time and motor run down time.
Essentially it is an on board controller which is unavailable to other types of power (rubber, CO2, Rapier/jetex).
The STC decided to do nothing and see what emerged - there have, to my knowledge, been no complaints, protests or disputes over their usage - yet.

So, taking this to the ultimate stage of controlling, - if someone uses an on-board 3 axis gyro with servo control of all the surfaces, is it logical tech progression that we all embrace?  Or, does it get handicapped in the rules to "level the playing field" with those models in the same competition which are flown "au naturel"?

It is a difficult balance to achieve and will certainly require a couple of years to arrive at the "correct" amount of handicapping as we are seeing in the larger RC classes of F4C and F4H.  Last year K factor of 1 for gyro use vs. the K.15 of a non gyro equipped model.  This proved too much of a scoring handicap for the gyro user, so this year it is K7.5 vs K15 and there are 12 or 15 competitions though the year for us to review the scores and see what the trend is. 

Free flight is somewhat trickier, as with RC we sort of know how good certain pilots are and the regular models they fly. 
FF can be a lottery, as they are much more affected by wind gusts, thermals etc.

Just some of my thoughts - it ain't as easy to please everyone as it might seem.

John M (STC)
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« Reply #9 on: March 19, 2018, 10:04:12 PM »

Steven,
          This is something I have been pondering ever since I watched your Hurricane at Barkston. One rational is that mechanical system has been replaced by an electronic system that is inherently more sensitive and faster in response. You can also add other control laws as part of the system. This is all part of the changing capability that can allow us to build models that would not otherwise be possible as they are inherently unstable, at the cost of complexity and the need of in depth knowledge turning it into another skill dominated event. Three axis control is essentially an autopilot. The idea of a handicap I think is a good one and can at least be modified after experience and should be implemented with dispatch and idea that it may require modification. I wonder what the takeup will be given the lack of large electric models!
Clearly none of this will be easy, but the tide of change is not going to go away, and surely using the good to improve flight experiences must be a good idea .
At the moment the leveling of the CO2 and electric classes would be a good start, by setting an energy level allowed by electric motors. 
   Ricky
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Prosper
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« Reply #10 on: March 20, 2018, 02:31:26 PM »

Quote from: billdennis747
I'm not sure a negative bonus is necessary. . .

Funnily enough, I just came across this here little parable - it was scribbled on a piece of paper that was acting as a bookmark in a Br'er Rabbit book:

Sidney Snodgrass entered his model Hawker Hurricane with scale dihedral and active ailerons in a flying competition. Percy Prendergast entered his Hurricane which was the same size but had fixed ailerons and an extra 3° dihedral on each wing.

Both models flew the same durations and the judge gave them the same flight realism scores. Then the judge looked at the wings of Percy's model and said, "this looks bloody awful, this extra dihedral on a Hurricane. Ten points off. Sidney Snodgrass is the winnahh."

Percy looked shocked and blurted to the judge, "but if I may be so bold, O Great Majesty; that Sid Snodgrass is a worm and a low cheat. He has sneakily hidden auto-stabilisation in his wings."

Sidney turned quickly to the judge and responded, "O Mighty and Infallible One, may I respectfully point out that that snivelling cur, Percy Prendergast, also has auto-stabilisation in his wings but it's not hidden (more's the pity): it's that extra dihedral, which has just as powerful a stabilisation effect as my ailerons."

The handsome and intelligent old judge frowned, and. . .


Sadly the paper was torn off here, but I did get the gist of the dilemma. Dihedral is a stabilisation feature of an aeroplane, as is a tail. I don't know how severely judges penalise over-scale dihedral in competitions, but I don't see why they should feel moved to penalise active ailerons (or other surfaces) at all, so long as the dihedral and the ailerons are to scale. If a model with active controls is considered somehow less 'free flight' than a fixed-control model, well then a model with extra added dihedral is less 'free flight' also. For a given scale subject, and all else being equal, there is a value of extra added dihedral of one model which matches the efficacy of an active-aileron system of another that has scale dihedral. That's a slight simplification since dihedral and active ailerons don't act in exactly the same fashion, but it seems a good starting point to me.

3view Steve may have perfected his system to the point where a low-dihedral model can fly 'on rails' even in blustery bumpy conditions. If that's so then it's still a free flight model IMO. Observers, including judges, might decry the fitment of micro-electronic gizmology to a luvverly stick-and-tissue creation but that's not the point. Steve has no influence over his model after launch, any more than a builder who's added some tail area to his model and stuck a big trim tab on the wing. It's free flight. It's scale. So why handicap it?

Jus' my thoughts,
Stephen.
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DHnut
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« Reply #11 on: March 20, 2018, 03:30:58 PM »

Stephen,
            That sums the whole issue up very well. there is another wease that is used that I am sure you have seen when the wing fixing allows the wings to assume more dihedral when under flight loads to assist stability. Is that always detected or penalised? Does it matter if it results in a satifactory flight. I think the capability will improve and give us another option.
      Ricky 
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« Reply #12 on: March 20, 2018, 05:41:19 PM »

Stephen

A well reasoned out argument for not penalising the use of auto stabilisation.

The problem will be when competitors who can't afford, don't understand the tech, or just don't want to change, either complain or protest the competitors who do adopt the new technology.  Then the STC has to make a rules adjustment which then pisses off one group or the other and entries fall because "its not fair" or "its not a level playing field" and then the STC get the blame.

How about having Sidney and Percy sit on the STC and come up with a sensible agreement of rules changes which will then suit all competitors?
That's the hard part.

John M (STC)
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« Reply #13 on: March 21, 2018, 05:28:47 AM »

Thanks for some interesting discussion.  Doing nothing until, god forbid, a stabilised model wins Superscale, sounds good to me.

Steve
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DHnut
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« Reply #14 on: March 21, 2018, 05:55:09 AM »

Now that would really start a debate!
Ricky
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