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F3J/F5J flap deployment setup.


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I presently have my flaps set up working in a fairly linear manner, on my "throttle" stick.

Having used flaps over the last few years, first on my 2m models and now on open class F5J models, I can't recall having had a real need to apply partial flaps at any point in my flights, but have had unwelcome and sometimes dramatic pitch changes due to flap deployment.       Given that, in my gliders, the pitching response can be proportionately higher than when full flap is deployed,  I'm wondering if I might benefit from making the flap operate as an "all or nothing" function (possibly by changing the curve to act very sharply from little or no flap to full, so that I can continue to use the stick for control).   

I realise that this is one of those things that is a personal preference,  but might the loss of partial flap positions create problems?    

(I don't mean to change camber/reflex control, that's a different function.)

 

 

 

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If you are describing flap use for braking or butterfly/crow braking then most transmitters have an elevator compensation mix or if not you could add one.

The pitch changes happen because the centre of pressure moves with flap angle (flaps down, CoP moves forward, nose pitches up).

Most of the pitch change happens in the first third of flap deployment so the curve is programmed to follow this.

It is possible to adjust the curve points in flight depending on the transmitter (launch high and use brakes, fly with the glider fuselage side on so that the pitch changes can be clearly seen).

    Gary

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Phil.Taylor

As Gary says - get your elevator compensation sorted out - usually quite a lot of down needed. A linear mix will work fine, a curve is better if you have a fancy tx.

Keep flaps/crow proportional on the throttle stick - use it to control the height/descent angle on landing approach.

Phil.

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I use a flap-elevator mix.  This needs work to arrive at a suitable amount of elevator for any given flap setting (if there is one).  Setting this up is a chore to say the least, it's a try it and see arrangement.    

Is a single braking flap position is desirable, rather than linear flap deployment that may require a non-linear mix with elevator?  

Does anyone use flaps in this way?

      

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Trying to answer but the forum is throwing an Error 403 Forbidden and blocking my IP address (I am logged in), will try again later.

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I'm obviously using too many words, if I keep it short it allows posting! The answer to the last question is no, not in F5J at least.

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Soaringjim1951

I am a fairly dreadful pilot and I need all the help I can get. I have a Taranis so I am free to do what I want. I use the throttle stick for Brakes and have 4 stages. Stage 1 is just a bit of down trim to make sure the glider flies smoothly and puposefully around the approach. Stage 2 is 25% brake, Stage 3 is 60% and Stage 4 is 100%. The Curve to drive it looks like a staircase, and so does the elevator compensation that goes with it. It sounds complicated but its a dream to fly. There's no guessing how far the stick has moved. Its obvious when you look at the approaching glider.

You can hear the howls from the pundits already, but it has improved my landing scores so I am deaf to them.

I do the same with the Flaps on a slider. 3 positons (Slow, Cruise, Fast) with appropriate elevator comp.

 

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1 hour ago, Gary B said:

Just sent my original answer as a PM which appeared to work.

I received the message Gary, thanks.      I was a little confused by the analogy with full sized glider control, maybe lockdown has dumbed me down too....   

I fully understood your message that a single position flap is not used within F5J.   Thanks. 

 

 

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32 minutes ago, Soaringjim1951 said:

I am a fairly dreadful pilot and I need all the help I can get. I have a Taranis so I am free to do what I want. I use the throttle stick for Brakes and have 4 stages. Stage 1 is just a bit of down trim to make sure the glider flies smoothly and puposefully around the approach. Stage 2 is 25% brake, Stage 3 is 60% and Stage 4 is 100%. The Curve to drive it looks like a staircase, and so does the elevator compensation that goes with it. It sounds complicated but its a dream to fly. There's no guessing how far the stick has moved. Its obvious when you look at the approaching glider.

You can hear the howls from the pundits already, but it has improved my landing scores so I am deaf to them.

I do the same with the Flaps on a slider. 3 positons (Slow, Cruise, Fast) with appropriate elevator comp.

 

Thanks for your input Soaringjim1951..      What you have done is along the same lines as my efforts/experiments.      I have tried flap deployment in two stages (plus zero flap), set up pretty much as you have described in OpenTx, but with two steps within a curve.  I had reckoned that two stages would be easier to apply suitable elevator compensation for.     So far, this setup is on one of my gliders (not flown very much this year).  I am considering "rolling" this out to my other gliders, but it occurred to me that this could make for a great deal of setting up, for each glider, all of which are likely to respond quite differently to varying amounts of flap, even two.    

Some of those flying in comps (those that I have watched during landing), seem to give stabs of full flap rather than a varying flap, but this is very difficult to see at any distance.... maybe I should ask them.     

One downside, I guess, is that applying full flap when at speed might not work quite as expected.    

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Cool, wonder if my post will work this time?!

In a powered aircraft the throttle control moves forward for more power, two other engine related controls also move forward for more power, fuel/air mixture control and constant speed propeller control (full forward is fine pitch).

In a glider the airbrake or spoiler control is usually held forward by an overcentre geometric lock, this is the closed position (full power!).

Unlocking the airbrake and pulling the handle rearwards applies more airbrake until full brake is reached (idle power).

With both types of aircraft approach airspeed is controlled by the elevator (right hand) and the rate of descent is controlled by the left hand (throttle or airbrake). 

The silver coloured lever on the left is the throttle of a Tiger Moth (in the idle position).

100_0926.thumb.JPG.225c87a57c01b906682bd8cb909d89ae.JPG

The grey lever with blue paint on the left is the airbrake control of a Mini-Nimbus (in the brakes close position)

100_0503.thumb.JPG.e1f68e5abcac1a7d5974764de7b4f3e9.JPG

 

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I recall that the glider spoiler is forwards to lock off.     During my glider trial lesson, my instructor told me of an incident he had recently read about, where student taking one of his first solo flights (launched onto a slope) had  decided not to use the cushion in the seat (I understand this, being a little too tall to fit well into the cockpit myself).    One of his pre-checks was to try all the controls for correct movement and feel). His new sitting position meant that he couldn't actually reach to the full spoiler off position and was too low and far back in his seat to be able to see the spoilers.  He managed to launch with the spoilers slightly deployed and ended up at the bottom of slope between trees and a formal investigation.   

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Phil.Taylor
1 hour ago, Gary B said:

 

1 hour ago, Gary B said:

With both types of aircraft approach airspeed is controlled by the elevator (right hand) and the rate of descent is controlled by the left hand (throttle or airbrake). 

 

But Gary - for many modellers, flaps/CROW/spoilers is "brakes" to slow the plane down 🙂 i.e. no notion of the concept of approach control, of controlling speed with elevator & height with CROW

I dont fly F5J (though theres a electric fus headed my way) - but doesnt F5J have a landing bonus? - so I would have thought that you'd want as much control over your landing approach as possible - putting flaps/CROW on a switch seems way too crude. I'm usually flying on a windy slope, so I need proportional approach control to get the plane down safely - I will be varying the CROW all the way down, which I can easily rely on because I've got the elevator compensation set right - and it really doesnt need a fancy curve - I flew for years with a linear mix until I got a fancy Tx.

Hope that makes sense?

Phil.

 

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As I was a full-size pilot long before I started RC flying I've always compared various techniques and used them if they work.

I couldn't loop a model very well initially because I was trying to not exceed (non-existent) G limits.

On my model glider approaches (to the last metre of the F5J landing tape for 50 points) the model is trimmed for approach speed early (by switching to a landing flight mode) and the descent rate/approach path controlled with the crow brake. What is missing here is a view of the landing area reference point, it's easy (once learnt) to recognise overshooting and undershooting in a full-size aircraft and correct it. Somehow I've learnt over the years to land a model accurately without that feedback.

My landing flight mode also removes roll control from the flaps, increases aileron movement and adds a large aileron/rudder coupling mix.

In F3J the top landing marks are 100 for the last 20 cm of the landing tape, I used to manage it occasionally but I'm not sure how I did it! 

I have seen accidents/lost comp flights with model flyers not having braking flap available in all flight modes, I don't really understand why flyers programme transmitters that way, on one occasion I was hit in the legs while timing/spotting, no injury or glider damage thankfully.

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Just re-read Phil's post. Controlling speed with airbrake/throttle is the wrong technique in full-size flying apart from loosing control in a cloud in a glider where opening the airbrakes fully is vital to prevent speed build up past structural limits (VNE - Velocity Never Exceed).

The drill for climbing is PAT (increase Power,  change Attitude, Trim) and descending is the reverse (APT).

There are times when I deliberately slow down a model glider on the approach and that is when I'm early (too many seconds left on the clock). In that case I close the 'brakes' and pitch nose up to slow down, having a headwind helps.  Don't do it often but it's satisfying if it works.

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  • 3 weeks later...

To practise landings, set up your flaps / ailerons for full crow movement on a switch.

Place a representation of the landing spot on the ground. (I like a white plastic bag) Simply switch on brakes and dive at spot.

How hard can it be to hit the centre of the bag. Done correctly you cannot slide away from the centre.

Here we are - landed to perfection.

PerfLand.thumb.JPG.f95bf71216bbb1d7ba6bed0786467d64.JPG

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isoaritfirst

😄 Do they measure depth past the spot??

After all anything above the spot wouldn't count. 

Seems only fair

 

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No, all measurements (about landing) are 3 dimentional - - Left and right, backward and forward and time.

The launch is 2 dimentional height and time and most of the flight is one dimentional - time.

Though meeting the ground early in the flight, probably makes that 2 dimentional.

On Planet Earth, in this universe, landing a foot above the spot is not an optional, just a transitional state.

 

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