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Crow Brakes

Piece of String question

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Alex Leigh22/06/2011 21:24:51
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Love crow brakes. Still not absolutely sure I've mastered their use tho. Because those who have seem to drop the model at their feet at walking pace, where I'm either out the back out of sight somewhere, back over the front or having to retrieve the model from an emergency bracken burial.
 
Okay it's not that bad, but I do have some questions
 
1) Is "optimal" crow when the model is pushing forward slightly but basically just coming straight down.
2) On the Bird, I need more down elevator (proportionally) for the first half of the crow than the second. So if I left it programmed as a standard mix from 0mm to 5mm comp for about 70 deg max of crow, it'll rear up until half way and then settle down. I've used a mix to tame it and checked all the movements, it just seems odd.
3) Is it really as simple as "get it into wind, wind in the crow"?
4) I guess this is wind / slope dependendant, but is it better to start with less crow and build it up if you feel you're overshooting or dump the lot and modulate back from there? I find I get a bit "thumb confused" trying to fine tune lots of things in quite a short amount of time!
 
I still feel like most of the time I'm coming in too fast. I need to trust the crow will slow the model down but it won't tip stall (that's how I wrecked my Luna). Every landing is different, most of them are okay, some quite good and I've not wrecked a model for a while but I really want to be able to nail it everytime.

So any advice useful. Happy to chuck/circuit/land for practice.
Tom Satinet23/06/2011 11:41:04
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Alex,
 
I think it depends on the circumstances in terms of the best approach. on some LZs in some conditions you can basically park the model and come down vertically or even backwards, but that approach can backfire if it's a bit more turbulent.
 
What you can find is that the model will fly slower with the crow out than with it in. What can happen is the the model stalls when you put the crow away. usually what happens is that you do a small belly flop just before you touch down, because this is when you usually put the brakes back quickly.
 
In terms of the non linear response of the pitch change (it's not that odd for it to be like that BTW) - try moving the stick more slowly. I guess it depends on the point that the flaps stop increase in the lift and have move of and effect of increasing drag. Also you might find that one pair of servos moves somewhat faster than the other(s) (or the tail). When setting up crow you basically usually try for "plenty" of down flap - try altering the amount of up aileron - sometimes it can work well with quite a lot, in my experience. Every model is indeed different.
 
What tends to happen if you are not careful on crow landings is that you chuck in a load of crow and then realise that it's too much (your going to be short), you put them away again, then you think, i'm overshooting, then you put them out again etc. This can lead to going to slow and falling on the wing, etc. I find it is generally better to try and put it in gradually, although sometimes I like to slow the model up with crow (esp. if there is some height), take them off again then bring it in.
 
As you say it is a question of working the 4th axis which takes a little getting used to if you are not used to crow brakes (I guess if you are a power flier it is easier, i don't know). I tend to try and fly a circle of square approach and use the brakes when the model is in to the wind, but you can use them to control the model a bit coming in to the slope, e.g on a slope side landing.
 
What I would say is a good idea, just in my experience, is to pick an exact spot that you want to land on and try and get near it. Sometimes I find that landings can be a bit aimless if you don't actually set out to achieve a specific target. I.e you tend to dump it in a general area if you are being reactive rather than proactive. Well i found it helped me improve anyway. If you are flying somewhere like the mynd this can be the case because you can basically land anywhere.
 
I think it is just a case of settings tweaking and practice really. I think in landing you have to be honest with yourself and ask yourself "was it really a good landing?" rather than being happy if you got away with it or taking the view that any landing with no damage is a good one (which it is in a way of course!).
 
As I say, try changing the aileron settings and don't worry about the model flying slowly (not too slow though, if it's rough!).
 
hth
 
Tom
 

Lee Morgan23/06/2011 12:19:06
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I agree with Tom ( make note you won't see me say that very often lol )
I must say I learnt most from doing F3F, You have to launch and land quite a lot . Also there's an amount of disgust if you need to go round again .
 
Easiest answer : Go to the slope with one goal , risky as it might be but go with the sole intention of launching and landing . You will get used to how each of you models behaves ( that day/weather/wind ) and you will normally find the one you like most .
The hard bit is getting all of your models to where you feel is best landing setup. As Tom says each model is different .
 
Have fun , get it sorted and you will benefit loads due to not having to do so many repairs
 
Lee
Ben B23/06/2011 12:21:52
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Just remember that reflexing up the airelons in crow braking increasing the chance of a tip stall so make sure the air speed stays up enough. Adding and removing crow braking sounds a good way to induce a tip stall!
Alex Leigh23/06/2011 13:06:43
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Thanks Tom/All. That's really useful advice. I shall go practice landing "on a spot". I did try that last week but was frustrated on how useless I was! I think the idea of bringing the crow in more gently and adjusting it gradually makes a lot of sense.
 
I need to fly a squarer circuit as well. Because I'm always really rushed on landing. Final turn is a bit tight, then I'm flying towards myself so I'm just not getting a feel for distance, then - generally - it's all a bit of a panic.
 
Funny now, flying isn't an issue mostly. I can feel myself improving. But all the time I'm thinking "got to land this thing soon" and it's a bit off-putting!
 
Practise then. Bird is a tough old *er* bird. Even so let's hope I learn fast eh?
Tom Satinet23/06/2011 15:05:05
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Posted by Ben B on 23/06/2011 12:21:52:
Just remember that reflexing up the airelons in crow braking increasing the chance of a tip stall so make sure the air speed stays up enough. Adding and removing crow braking sounds a good way to induce a tip stall!
 
Ben, if that were true then washout wouldn't be something which they put in some model (e.g gentle lady) to improve low speed handling.
 
 
Tom Satinet23/06/2011 15:06:38
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Posted by Alex Leigh on 23/06/2011 13:06:43:
Thanks Tom/All. That's really useful advice. I shall go practice landing "on a spot". I did try that last week but was frustrated on how useless I was! I think the idea of bringing the crow in more gently and adjusting it gradually makes a lot of sense.
 
I need to fly a squarer circuit as well. Because I'm always really rushed on landing. Final turn is a bit tight, then I'm flying towards myself so I'm just not getting a feel for distance, then - generally - it's all a bit of a panic.
 
Funny now, flying isn't an issue mostly. I can feel myself improving. But all the time I'm thinking "got to land this thing soon" and it's a bit off-putting!
 
Practise then. Bird is a tough old *er* bird. Even so let's hope I learn fast eh?
 
You'll be surprised just how far back you can go and still make it to the lip (slope dependant) with a mouldie/efficient model.
 

Alex Leigh23/06/2011 15:09:59
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I always assumed ailerons up was to prevent tip stall as well! Yes I've noticed how wooshy the mouldies are. Then I go and fly my old middle phase and it ends up miles away!
Isoaritfirst23/06/2011 23:27:31
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When ever I have put curves into the elevator response to the crow, I have some time later taken them out and found it better.
 
Curves can be to conditions dependent, just put a nice linear compensation in and try adjusting the amount of up aileron, and learn just how to apply the brakes.
I usually add them in slowly untill full brake then having killed some speed back it off to the right amount to allow the model to fly to roughly where i want it to be.
 
I do try to land it where I intend to but do not mind if I end up safely down some distance back from the planned spot. Especially if the conditions are rough or I am carrying a lot of ballast.
 
Don't try to stretch the glide unless you are very sure that the conditions are good for it.
 
Trying to stretch a glide path out may mean you end up nose high with no speed and heading into trouble. If the model is good to land then land it and walk.
 
Hit the spot you aim for by good planning early in the approach not by dragging it out.
Alex Leigh24/06/2011 14:48:26
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Thanks Mike. More good advice. I'll go back to a linear comp then and try to be a little less punchy on the stick.
Lee Morgan24/06/2011 19:24:14
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Alex just as an example watch my vec vid to the end and youll see me putting the brakes on and off to end up with it landing almost at my feet
 
 
Lee
Alan Dunstan26/06/2011 08:40:46
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We all manage a lucky one every now and then don't we Lee....
 
Alan
Lee Morgan26/06/2011 09:10:55
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I think if you look through your video archive you'll find lots of lucky one's of my landings lol your only jealous mate
 
Lee
Chris van Schoor26/06/2011 10:30:28
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Posted by Lee Morgan on 23/06/2011 12:19:06:
Also there's an amount of disgust if you need to go round again .
Lee

That's very unfortunate, Lee. I find that that mind-set can result in many a crash if one is still practicing to get your landings "pat". I think's it's a vital part of your mind-set that you can go around as many times as you want - rather do that than "force" the model to land when things aren't quite "right"...

Tom Satinet26/06/2011 14:34:51
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I've had to do plenty of landings where a go round is not an option due to lack of lift/sink!
Chris van Schoor26/06/2011 16:51:14
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Weird slopes you fly at Tom (or is it that you just have to automatically gainsay everything I say?)!
Tom Satinet26/06/2011 19:23:09
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that wasn't my intention Chris.
 
I have done a few down winders as well in my time. All good clean fun!
Alex Leigh27/06/2011 08:27:42
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Nice vid that Lee. I have something to aspire too.

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