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Rolling a model twice

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Dave Bond 228/09/2015 11:54:20
14 forum posts

Hello all,

For the B certificate I see the requirement for rolling the model twice in both directions without pause in the middle.

I am flying a Cougar 2000 and though I appreciate that the B certificate is a measure of skill. I am finding rolling twice maintaining altitude much harder than I feel it should be. I see other people flying models and do not seem to be fighting their model half as much.

I can fly in level flight and inverted with very minimal correction using elevator. When trying to roll I always seem to be loosing altitude at the point of entry into the second roll. The cougar has a very thin sectioned fuselage, so at 90 deg I wonder if as there is no lift from the wings and minimal resistance from the fus I am loosing altitude at the four times the model is in this attitude.

So I am wondering what is the trick in getting this model to preform the roll nicely.

will -028/09/2015 12:08:20
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552 forum posts
19 photos

Usually it's a dab of down elevator as you pass through inverted.

Cheers

Jon Laughton28/09/2015 12:16:11
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1171 forum posts
104 photos

I originally had the same issue but to build confidence and control there is a cheat, albeit one recommended by the RC Flight school in the USA: a small dab of up elevator just before the rolls will help and if done correctly is hardly noticeable - also maximising the roll rate (i.e. aileron defection) to the fastest rate where you are comfortable will help but if this results the models rolling in a 'blur' it will not be considered acceptable by the examiners....so experiment if you can.

And good luck!

Edited By Jon Laughton on 28/09/2015 12:16:52

Andy Green28/09/2015 12:16:32
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2279 forum posts
67 photos
2 articles

What I would suggest is have a low rate set up, and when you are about to do the 2 rolls, switch to the low rate.

This rate should allow the model to roll suitably slowly with the stick hard over, then all you have to worry about is the timing of the dabs of down elevator.

A

iqon28/09/2015 12:20:09
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1437 forum posts
238 photos

Practice doing slower rolls

Dave Bran28/09/2015 13:01:29
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1898 forum posts
5 photos

I think with that model you have as you suggest the issue with the small area of the Fus when on wing tip, and to correct that you'd need to dab correcting rudder just like dabbing corrective elevator when inverted. The issue with the Cougar is that it's rudder is heavily cross linked to elevator, which will require adept stick handling.

Have you experimented with the effect of roll direction?

Bottom Line............The Cougar is a Fun Fly machine, designed to be thrown around, not do smooth aeros in the very specific "B" cert style.

As the country yokel said when asked what the best way was to get to Ashover, "if I were going there I wouldn't start from 'ere"...............................

(I own one)

Martin McIntosh28/09/2015 13:04:39
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2819 forum posts
1050 photos

Don`t expect a model to maintain height without using a little down elevator when inverted. The rules state that the use of elevator is demonstrated during the manoeuvre. Practice this doing three consecutive rolls, then two should be easy. Set your roll rate to three in five seconds. Anything quicker is really not acceptable but you may do these as slow as you wish.

ken anderson.28/09/2015 13:28:14
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8409 forum posts
772 photos

hello Dave...don't have too much movement on the controls ail round.....and don't fly too fast.......and a dab of down in when the model is inverted....i have a C2000...and it will roll from one end of the sky to other....bit of practice/standard settings -you will be ok.

ken anderson...ne...1 rolling dept.

john stones 128/09/2015 13:35:00
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10381 forum posts
1475 photos

Models fine for a B test, it's requires same as A test (safe and in control) but to a higher standard, took mine with a clipped wing cub. Sounds like you're not releasing dab of down correctly Dave or you're flying too slowly and it's killing airspeed with first roll. If you can do one roll you can do a dozen, it's just timing the dabs

John

Dave Bond 228/09/2015 13:38:27
14 forum posts

Thanks all, I will give it a go. There are some very good points here.

Mowerman28/09/2015 13:54:01
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1532 forum posts
105 photos

As will-O suggests, a dab of down elevator as the model pass through inverted. I practiced this on my sim until I was happy then used it on the real thing success.smiley

Percy Verance28/09/2015 14:08:32
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8067 forum posts
155 photos

I'd consider a different model personally. I don't rate the Cougar at all. It's an awful thing. Too light and too *flicky* to be a smooth aerobatic flyer in my opinion.

I would stress again, it's purely my opinion........

Edited By Percy Verance on 28/09/2015 14:09:20

Biggles' Elder Brother - Moderator28/09/2015 14:17:38
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15748 forum posts
1460 photos

John S is right, in essence! If you can do one roll you can do a dozen. But behind that statement lies a bit of an issue! When you do your first roll are you in reality exiting it just a little nose-down? You see in one roll that doesn't matter so much - you can get away with it. But when doing two rolls, one immediately following the other, its a big problem, because now you are entering the second roll slightly nose down and its really all going to go to hell in a hand cart from there on in!

I think the secret (if there is one wink 2) to doing a good double roll is to nail the first one spot on. Get that right and you enter the second roll in level flight - get it even slightly wrong and you have your work cut out to hold it all together.

So, what I would suggest is go back to practicing single rolls in both directions for a flight or two. Concentrate on being sure that you exit the roll absolutely level - don't accept even the slightest nose-down exit. As has been said the well timed "dab of down" when inverted is the key here.

Then add the second roll. Because you are now entering the second roll level you should find it easier. If still having problems consider a tiny dab of up elevator when the model is level bewteen the rolls so you actually enter the second roll very very slightly nose-up.

If the timing of the dabs is causing you problems it a very good idea to practice on the sim - but in slow time - say 50% to start with and gradually increase to 100% (real time).

BEB

John Muir28/09/2015 16:06:17
365 forum posts
1 photos

Lots of good advice there.

I'd second cutting the aileron movement right down so that the model rolls at the rate you want with the stick full over. You can then concentrate on getting the up/down inputs right without affecting the roll rate, especially if you're flying mode 2. On a fun-fly model the ailerons are almost certainly massively over-sensitive for smooth flying. I'd also go with a small dab of 'up' on entry, a slightly larger dab of 'down' when inverted, then another dab of 'up' for the second roll and so on for as many rolls as you want.

With a model of this sort I'd stay away from the rudder although, technically, using opposite rudder as the model passes through knife edge is the way to get a nice smooth roll. If the rudder induces a roll as a secondary effect though it won't help. You really want to be using the elevator to lift the nose after each turn through knife edge when it will inevitably drop. For a while the rolls will look 'lumpy' but with practice your timing will improve and it will all start to look smooth.

will -028/09/2015 16:38:10
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552 forum posts
19 photos

I could be wrong here, but I don't think the b test is meant to be a pattern competition, so use of rudder during the roll to produce a perfectly axial one is not expected, just the aforementioned elevator correction to prevent a dive developing.

John Muir28/09/2015 17:20:06
365 forum posts
1 photos

I only mentioned rudder in response to the OP's first post regarding the nose dropping when the model's on it's side. Top rudder would be the ideal way to compensate for that but it won't be any help if the plane has roll coupling to the rudder, which his funfly almost certainly will. And as I said, I wouldn't use the rudder, I'd stick to elevator in an 'up,down.up down' sequence, the point being that you need to lift the nose after every knife edge part of the roll, not just when the plane is inverted. If you only use 'down' when the plane's inverted you'll need to use almost twice as much input and things really do start to look lumpy then.

Willyuk28/09/2015 20:38:22
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176 forum posts
22 photos

Hi Dave,

I spent this year practising for the b test and i too found the two rolls difficult. I would recommend reading the thread on aerobatics by peter jenkins( just search for aerobatics and look for " ever thought of getting into......" ) it is really usefull. I too set my transmitter up to have a slow roll rate, i practised with a rate of 6 to 8 seconds to complete the two rolls. That is far slower than called for but does make one work at it! Then of course it has to be centeted. I left that until i had the rolls sorted, then adjusted to get the centre correct. Then adjusted again for wind. As said above the test calls for an obvious use of down elevator when inverted. A small amount of up before commencing the roll is acceptable i believe. MOST IMPORTANT the rolls are performed slowly but the aircraft is NOT flying slowly. I found i had to add speed prior to starting to roll, this stops the plane flopping about. Not too fast but above normal cruise i would say.

Good luck!

Tim Hooper28/09/2015 22:14:13
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2853 forum posts
2363 photos

Initially I'd split the procedure into three separate parts;

1. Roll

2. Inverted

3. Roll

Practice this, gradually decreasing the inverted phase until it all merges into one smooth progression.

tim

ben goodfellow 128/09/2015 22:30:59
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1069 forum posts
41 photos

nobody use else use rudder when rolling ?

Stuphedd28/09/2015 23:00:31
637 forum posts
338 photos

the two examiners I had said they would like to see the inputs during the rolls , and afterwards they said try it again and this time DONT make them so obvious.

I spent many months practicing and fine tuning the aircraft so it needed a minimum correction input from the pilot, like the "normal screw" when finishing the "bunt "

it was a pattern type .

cheers

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