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» 2019 Llanfair TH Village Fete
Brakes up or down? Empty2019-07-12, 18:53 by Rich

» Proposals for Model aircraft flying ( CAA registration) April 2019
Brakes up or down? Empty2019-05-08, 17:49 by Gary M Jones

» Police crash
Brakes up or down? Empty2019-04-14, 15:36 by Roy

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Brakes up or down? Empty2019-04-13, 16:49 by Roy

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Brakes up or down? Empty2019-03-03, 23:44 by Charles E Cornes

Saturday 7/7/18

2018-07-07, 21:07 by Gary M Jones

I was at the field today between 14:00 & 15:00 all on my own , good flying too. There is a dead sheep along the fence line towards the gate from the pits, I saw the farmer so reported this to her. I hope no one had plans for a BBQ Smile .

Farmer …

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Brakes up or down?

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Brakes up or down? Empty Brakes up or down?

Post by Marty 2011-12-16, 11:42

I am in a quandary, I was under the impression that deploying the flaps down would act as a brake but a friend has told me that this will promote tipstall. He suggests that the Flaps should go up for brakes.
My Akcent wings have the flaps / ailerons hinged on the bottom so the up travel is limited but I would like to know peoples opinions on this.
Cheers,
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Post by Rich 2011-12-16, 12:14

For DLG down matey.

Down increases lift to an extent then drag after a certain amount of deflection, induce down elevator to increase the speed to prevent stall this is normally mixed in proportional to the amount of flap.

Up reduces lift & increases speed, you then have to induce up elevator to reduce the speed. Mixed in the same as above, only up elevator.

Read the instructions to get the throws exactly right

There will be a few mixes to setup
Launch, neutral, increased lift, reduced lift, landing etc

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Post by Rich 2011-12-16, 12:21

read this lot unless you already have

http://olgol.com/Akcent-2/build.html

I can't wait to have a go

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Post by Guest 2011-12-16, 12:29

Applying flaps/ailerons UP (spoilerons) will not slow the model - just will increase the descending rate (also usefull in some conditions) - as there is decreasing in creating the lift in fact will speed up the model in some cases - depends how much they will be UP - often used for termal gliding when you need to jump from lift to lift .
Applying flaps/ailerons DOWN (flaperons) - will create more lift - so the model can fly slower - it will create "some" braking force - but it's not gonna be a big enough difference to call it breaking Wink



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Post by Guest 2011-12-16, 12:31

bit to late ... Sad

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Post by Marty 2011-12-16, 12:41

Thanks or the replies. Rich,Thanks for that link but can resite it almost word for word lol .... everything I have read in my research comfirms exactly what you have said but I was in contact with the chap I bought my Garnet from who threw the "up flap to brake" spanner in the works ....... He's quite an exprienced DLGer so I began to doubt the info I had. He was saying that Down flaps for brakes is a sure way to tipstall.
I looked up the info for the Garnet and the specs say down flap for brakes, I'm just trying to understand why he would choose Up for brakes.
If it's "nice" weather on Boxing day I will bring the Akcent and garnet and you will be welcomne to have a go Rich Smile
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Post by Andy Sayle 2011-12-16, 15:28

Up flap for brakes is a load of tosh. Putting any control surface up on the trailing edge of the wing will only decrease the lift coefficient of the wing, decrease the effective angle of attack, and marginally (very marginally, depending on the particular aerofoil section employed) increase the drag coefficient. Translated into english, that means the plane will continue flying at the same speed, but start to head towards terrafirma faster. It is commonly used on sloper type models to imrpve landings because it effectively forces the model down quickly, reducing the need to fly close to the stall speed, and reducing the chances of overflying the slope edge.

Now down flap on the other hand, is just the ticket for braking, and it works wickedly well on lightly loaded models, such as a DLG (as well as heavily loaded models too). dropping the trailing edge down increases the lift coefficient of the wing considerably (the amount varies as per the aerofoil design, hinge position and amount of drop) increases the drag coefficent a fair bit, and also increases the effective angle of attack a fair bit too. The increased lift coefficient and increased effective angle of attack usually result in a sharp pitch up, which requires a healthy amount of down elevator to compensate (hence the need for the mix).

This tipstall alarky is a bit of an odd one too. tip stall is such a nothing description of what is going on. What is actually happening when a model flicks on you, is a an asymmetric stall, i.e. one wing entering a stalled condition before the other. The resulting asymetric lift distribution causes the funky gyrating and departure from controlled flight. This is bound to happen when you increase the effective angle of attack, beyond which the aerofoil design can cope with at a particular speed (i.e. when the flaps are dropped suddenly). The only way to deal with this, is the pilot correcting the flight by adding down elevator to counteract the effective increase in angle of attack. So someone complaining that a model is very tipstally, is usually trying to find a nice way of saying "I can't cope with flying this model, my level of piloting ability is not sufficient to deal with it's safe flight envelope". This is also why banging in the flaps on a switch is a bad idea, and gently feeding them in on a stick, lever or dial is much better. The gentle change in the effect aerofoil section (i.e. increase in angle of attack) can be managed by most pilots fairly easily, and the down elevator mixes actually stand a chance of working before the wing stalls.

I'm bored of typing now, I'm off to try and tame the tipstall on my vapor.... If only I had my portable whiteboard and selection of pens with me.....

Andy Smile

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Post by Mark Barnes 2011-12-16, 15:48

Andy Sayle wrote:Up flap for brakes is a load of tosh. Putting any control surface up on the trailing edge of the wing will only decrease the lift coefficient of the wing, decrease the effective angle of attack, and marginally (very marginally, depending on the particular aerofoil section employed) increase the drag coefficient. Translated into english, that means the plane will continue flying at the same speed, but start to head towards terrafirma faster. It is commonly used on sloper type models to imrpve landings because it effectively forces the model down quickly, reducing the need to fly close to the stall speed, and reducing the chances of overflying the slope edge.

Now down flap on the other hand, is just the ticket for braking, and it works wickedly well on lightly loaded models, such as a DLG (as well as heavily loaded models too). dropping the trailing edge down increases the lift coefficient of the wing considerably (the amount varies as per the aerofoil design, hinge position and amount of drop) increases the drag coefficent a fair bit, and also increases the effective angle of attack a fair bit too. The increased lift coefficient and increased effective angle of attack usually result in a sharp pitch up, which requires a healthy amount of down elevator to compensate (hence the need for the mix).

This tipstall alarky is a bit of an odd one too. tip stall is such a nothing description of what is going on. What is actually happening when a model flicks on you, is a an asymmetric stall, i.e. one wing entering a stalled condition before the other. The resulting asymetric lift distribution causes the funky gyrating and departure from controlled flight. This is bound to happen when you increase the effective angle of attack, beyond which the aerofoil design can cope with at a particular speed (i.e. when the flaps are dropped suddenly). The only way to deal with this, is the pilot correcting the flight by adding down elevator to counteract the effective increase in angle of attack. So someone complaining that a model is very tipstally, is usually trying to find a nice way of saying "I can't cope with flying this model, my level of piloting ability is not sufficient to deal with it's safe flight envelope". This is also why banging in the flaps on a switch is a bad idea, and gently feeding them in on a stick, lever or dial is much better. The gentle change in the effect aerofoil section (i.e. increase in angle of attack) can be managed by most pilots fairly easily, and the down elevator mixes actually stand a chance of working before the wing stalls.

I'm bored of typing now, I'm off to try and tame the tipstall on my vapor.... If only I had my portable whiteboard and selection of pens with me.....

Andy Smile

He's back Rolling Eyes

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Post by Rich 2011-12-16, 15:54

And in a long winded kind of way the same as I wrote, although Marty could understand my version

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Post by Andy Sayle 2011-12-16, 16:03

You missed me, didn't you?! Smile

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Post by Marty 2011-12-16, 16:07

Bloody Hell, I havn't heard from Andy in a couple of months but boy did he make up for it Razz
Thanks Andy. ans Yes, I for onw have missed you .........
Well this Brake up or down thing is, to my mind, cut and dried. I asked the same question on a couple of other forums and so far, (apart from the guy who originally yold me about up for brakes) it's 100% for down. that includes answers from UK, USA, Denmark & Switzerland so it's not just a reginal thing.
Thanks for the unput lads.
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Post by Andy Sayle 2011-12-16, 16:25

"unput". I like it Smile Smile


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Post by Marty 2011-12-16, 16:43

I don't understand all those typos?
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Post by Mark Barnes 2011-12-16, 16:55

Rich wrote:And in a long winded kind of way the same as I wrote,

Now there's a surprise Rolling Eyes

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Post by Brian Colclough 2011-12-16, 17:19

When I fly my Wasabi which is a two servo wing I drop both ailerons for landing and have never had a tipstall. This was on the advice of both the designer and "Mr Big" Andy Ellison. Wink

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Post by Allan Patrick 2011-12-16, 17:27

I find one up and the other down is a good compromise
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Post by Marty 2011-12-16, 17:31

I tried that aproach quiet a lot when I was begging to fly, the good was I always ended up landed, the bad was, not always in the postion or condition desired!
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