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Ailerons up or down


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Hi, l am finishing a 3.3m 4wing Servo sailplane,for general Slope soaring. My Tx is using a pre programme 6 channel   Sailplane set up .

l have set up the Spoi- Flap value and Flaps working fine. I now want to set up the Spoi- FPRN value for the Ailerons. I have seen sometimes both ailerons go up when Flaps deployed to act as a form of airbrake and otherwise ailerons drop so creating a full length flap. I want to obtain best control for losing height for landing

which is the better way to go ??? Many thanks.  Geoff 

 

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For thermalling the ailerons go down with the flaps, but only by a mm or two in general on a high performance mouldie. When braking though they go up (known as crow or butterfly braking) to wash out the wing and give lots of stability against tip stalling. In general most gliders of this type will have at least 60-70 degrees of down movement on the flap, but much less (maybe 10 degrees, 2-4mm) reflex on the ailerons. Remember also that as the ailerons go up you will want to reduce or even invert (i.e. go to more down than up) the differential you may have set in other flight modes. This will ensure you don't run out of aileron effectiveness when using large amounts of brake.

More info here on useful mixes for 4-servo wing gliders.

PS - I always put crow on the throttle stick to give instant analogue adjustment as you come in to land, and to make it easier to tuck the flaps away quickly just before touchdown to prevent stripped servo gears.

Edited by MattyB
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Thanks for replies.  Yes set up on Throttle stick .... closed in the up position and pulling down operates the Flaps, do easy to remember which way to operate and easy to push up to put Flaps away.

l easily get 60/70 degrees on Flaps but thank you for the information on 10 degrees up for Ailerons.... l would have gone for a lot more ???. By mistake.

so up it is ??

many thanks .. Geoff 

 

 

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17 hours ago, Geoff Daunt said:

Thanks for replies.  Yes set up on Throttle stick .... closed in the up position and pulling down operates the Flaps, do easy to remember which way to operate and easy to push up to put Flaps away.

l easily get 60/70 degrees on Flaps but thank you for the information on 10 degrees up for Ailerons.... l would have gone for a lot more ???. By mistake.

so up it is ??

many thanks .. Geoff 

NP. Having too much reflex on the ailerons is not a major issue tbh; it just means you will lose more aileron authority when brakes are active. Having ~10 degrees is generally a happy medium; it provides plenty of washout to eliminate any tendency of tip stalling, and all the drag you need is being generated by the flaps anyway. 

One final point... Don't forget to deploy crow at height first, as there will be a trim change when you do it. Try not to pull them straight out from high speed - let speed bleed off first, then pull it in gradually noting any trim change all the way to full brake. Models can require either up or down trim - it depends on a number of factors including wing section and tail moment - so doing it at height is highly recommended. You don't want your model nosing into the ground the first time you activate the brakes!

Edited by MattyB
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4 hours ago, MattyB said:

NP. Having too much reflex on the ailerons is not a major issue tbh; it just means you will lose more aileron authority when brakes are active. Having ~10 degrees is generally a happy medium; it provides plenty of washout to eliminate any tendency of tip stalling, . 

 

Having the ability to reduce differential as crow is applied can also offset this. 

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  • 2 weeks later...

Very interesting. I have the problem of losing aileron control with my Vladimir Models Graphite 2E when Crow Brakes are deployed. I have a Futaba 14SG Transmitter. I have never understood what programming you need to adjust the Aileron Differential when deploying Crow Brakes. How would that work?

 

I get the offset command which delays the deployment of down elevator until you use a certain percentage of the crow brake movement, and have tried that. I set it at 0% so that it comes in straight away.

 

There are other commands which I don't understand and the manual is written in Japanese English and is quite honestly mostly gibberish.

 

 

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Peter, Regarding losing aileron control when crow is deployed, it sounds to me as though you have too much up aileron. I normally have 10 to 15 degrees up as a maximum when I am at full crow braking and I use that figure for all my gliders from my 1.5 metre sports jobs to my 7 metre scalies.

I have crow braking set up on the throttle stick, so that I have precise control of the glide path on the approach to landing. The motor control I have on the left-hand side slider and that arrangement works perfectly for me, as the motor isn't used much, but juggling with the throttle stick is what's needed to achieve accurate landings.

 

BTW Peter, where will you be flying your Flamingo; will it be slope or flat-field? I mainly fly slope, but I am hoping to get to an aerotow meeting or two this year, pandemic rules permitting.

 

 

Definitely agree with you FlyinBrian. ?

 

I bought Malcom's book when I bought my 14SG a two or three years ago and he completely de-mystifies the whole process of programming the 14SG.

Well worth the five pounds and sixty seven pence that it will cost you.

 

As he says in the introduction, you don't need to read the whole book, just dip in for the bits of information that you need.

You will never need to look at the Futaba manual that comes with the radio again, and you will definitely thank Malcolm for that.

There is also  the added benefit that Malcolm frequents a number of forums and it is possible to submit questions to him.

 

https://www.amazon.co.uk/Futaba-14SG-Programming-Fixed-Aircraft-ebook/dp/B00BMM9J7A

 

Also read David Ashby's article on Crow braking in the May 2020 RCM&E.

Edited by Eric Friend 1
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15 hours ago, Peter Garsden said:

Very interesting. I have the problem of losing aileron control with my Vladimir Models Graphite 2E when Crow Brakes are deployed. I have a Futaba 14SG Transmitter. I have never understood what programming you need to adjust the Aileron Differential when deploying Crow Brakes. How would that work?

 

I get the offset command which delays the deployment of down elevator until you use a certain percentage of the crow brake movement, and have tried that. I set it at 0% so that it comes in straight away.

 

There are other commands which I don't understand and the manual is written in Japanese English and is quite honestly mostly gibberish.

 

 

Peter, reading the manual there is an option in the aileron differential setting to adjust aileron differential as the butterfly control is applied, page 120. So here you set the aileron differential for normal flight and how much it is reduced as you apply butterfly. In the Butterfly menu you set how much the ailerons are raised.

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This might also help, haven’t watched it all but it looks like it has a section on aileron diff....

 


i am imagining all you need to do is set the “butterfly adjust” percentage on the ail diff screen and you should be golden. Play with it and see.

 

CF6F59E7-027B-4095-9614-93A5B1B02022.jpeg

Edited by MattyB
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Thank you sooo much chaps. I have now read, slowly and carefully the chapter on Aileron Differential and Butterfly, and now understand completely the bits about fine tuning and Butterfly Adjust which were a complete mystery to me before. Such a good book.

 

I remember reading how Andy Ellison adjusts his Aileron Differential mid air to produce an axial roll but I had not idea how he did that - until now ie by assigning Fine Tuning to the LD knob type volume control at the top of the transmitter. I will do that now and experiment. Excellent.

 

Also it will be very useful to do the same with elevator compensation on applying Crow Brakes mid flight to make sure there is enough but not too much to land properly without crashing to get it right or applying the adjustment on the ground.

 

I am born again....but there again we are grounded at the moment aren't we? And can only talk in theory!.....? 

 

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On 26/02/2021 at 22:52, Eric Friend 1 said:

Peter, Regarding losing aileron control when crow is deployed, it sounds to me as though you have too much up aileron. I normally have 10 to 15 degrees up as a maximum when I am at full crow braking and I use that figure for all my gliders from my 1.5 metre sports jobs to my 7 metre scalies.

I have crow braking set up on the throttle stick, so that I have precise control of the glide path on the approach to landing. The motor control I have on the left-hand side slider and that arrangement works perfectly for me, as the motor isn't used much, but juggling with the throttle stick is what's needed to achieve accurate landings.

 

BTW Peter, where will you be flying your Flamingo; will it be slope or flat-field? I mainly fly slope, but I am hoping to get to an aerotow meeting or two this year, pandemic rules permitting.

 

 

Definitely agree with you FlyinBrian. ?

 

I bought Malcom's book when I bought my 14SG a two or three years ago and he completely de-mystifies the whole process of programming the 14SG.

Well worth the five pounds and sixty seven pence that it will cost you.

 

As he says in the introduction, you don't need to read the whole book, just dip in for the bits of information that you need.

You will never need to look at the Futaba manual that comes with the radio again, and you will definitely thank Malcolm for that.

There is also  the added benefit that Malcolm frequents a number of forums and it is possible to submit questions to him.

 

https://www.amazon.co.uk/Futaba-14SG-Programming-Fixed-Aircraft-ebook/dp/B00BMM9J7A

 

Also read David Ashby's article on Crow braking in the May 2020 RCM&E.

Thanks Eric. I have always dialled in more than 10 to 15% aileron but will now change to less for the Graphite which is the only plane where it seems to affect aileron and turning to such an extent that I was unable to use Crow for landing.

 

I fly only Slope but have just completed the Flamingo for which see my thread - because I would like to have a bash at Aerotowing, which Simon Cocker writes so much about.

 

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Thanks for your reply Peter, I'm pleased that my comments were of some help. Yes, I'm dedicated sloper as well and luckily here in Kent I can fly slopes in virtually every wind direction, with our main SW slope being less than 10 miles from my house. Some of the 'slopes' are cliffs and sea walls, but as long as there's wind blowing up and over it, then it will be flyable - Kent has a lot of coast facing the sea in various directions.

 

Yes, I have found that the percentage up aileron is determined by trial and error. I have often encountered situations where on a new model, crow is applied and it's a case of "Oops, I haven't any aileron control", quickly switch back to normal, land, reduce up aileron and try again. My latest little 'lockdown' slope mouldie doesn't have flaps, so it will be a case of up ailerons with up elevator to try and slow it down for landing - should be interesting!

 

I often see Simon Cocker at various events such as aerotow meetings at Middle Wallop, Baldock Tugs and Gliders and Ghost Squadron events at BMFA Buckminister. I also met with Simon at the scale meeting at Long Mynd a couple of years ago. As Simon lives somewhere 'up north', we don't see him on 'our' slopes in Kent and Sussex, however we do have the benefit of being able to fly regularly with David Ashby, now that he has become a sloping convert!

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