C of G For Control line models

[Steve Porter 1]

Hi All, I was given a control line model over the weekend,c/w PAW 2.49 Diesel engine, i was told the model is a Hallam Shorty but the C of G position was unknown hence the engine hanging on by the fuel tubing (fuselage broke clean off in front of wing, i have very little knowledge of control line models apart from flying a Keil Kraft Champ in the early 70s. Could any shed some light on where the CofG should be?

Many thanks.

Steve

[mal brewer]

Hi Steve,

the normal place for a safe c/g position on a c/l model is on the front line position { i.e. level with the front lead-out from the bellcrank}. I think you will find that to be a satisfactory position...............Mal.

[Keith Evans 3]

Hi Steve

R .G. Moulton's COTROL LINE MANUAL suggest it should be on or slightly in front of the front line at the bell crank position . the further forward ,the more stable it is and conversely if moved further back .

Make sure you off set the motor towards the out side of the flying circle together with rudder off set to achieve the same effect . Add tip weight to the outer wing and if you can , rake the front line back about half an inch at the tip .This all designed to keep line tension so you have control .

Best of luck .

[IanN]

to all the above. Always worked for us

[Steve Porter 1]

Thanks guys, Just pushed it all back together it seems to balance aprox 1/2" in front of leading edge!? which puts it way to far forward from the ballcrank, some serious rethinking needed here then! May try to move engine back / lengthen the tail a bit? thanks for your speedy replies!

Steve.

[Martyn Johnston]

Last time I flew control-line was in the mid 70s.

I remember the borrowed, fuel-soaked plane just getting up to full-speed and then catching fire.

It scared the crap out of me, and all my mates just ran off and left me in the middle of the circle !

[Josip Vrandecic -Mes]

@Hi Martin , those were the days....

Cheers

Jo

[Former Member]

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[John Privett]

Sorry Martyn, I shouldn't laugh, but that's hilarious!

I got into R/C via C/L many, many years ago, and whilst we certainly had a few fires (some accidental, mostly not) I don't think any of us ever had a mid-air fire! We'd frequently incinerate the wreckage of badly-crashed planes, and sometimes get spilt fuel burning on a model whilst starting the engine - at least on models with glow-motors and open exhausts.)

And oh yes, the memories of good old Nitrex 15 in little half-pint and pint tins.

[Mike Etheridge 1]

Before my nephew Nigel moved north to Bolton he was a member of the Three Kings control line club . As I have mentioned before Nigel was expert at CL flying and entered the top competitions. He could fly planes behind his back without looking.

I seem to remember if the CG was too far forward then a plane would not stunt well so it was always a case of moving the CG as far back as you could to the point where the plane became unstable.

Why not try contacting Steve Waller at the Three Kings Club ?

Model flying club specialising in control-line models. The Club has its own flying site at The Old Croydon Aerodrome, Purley Way, Croydon. PRO: Steve Waller, e-mail: [email protected] tel: 020 8310 6101

[Keith Evans 3]

Hi Steve

You will need some 50 foot light lines . You can still get these from P.A.W.

Don't forget to take off with your model and your self with back to the wind to get maximum line tension when the plane lifts off in front of you .

[Steve Porter 1]

Hi all, Thanks for all your help, managed to reconnect front fuselage last evening then decided to recover it, cofg now just in front of front line on bellcrank as suggested. Back to work tomorrow so probably finish it at weekend then try to fly it without getting dizzy and falling over LOL

Steve.

[Peter Miller]

Try to keep your arm and wrist straight while learning to fly, Later you can move arm, wrist and should in a smooth movement. Point you whole arm where you want your model to fly. Providing the elevators are neutral when your arm is pointed straight at the model this works well.

If you c an find an experienced control line pilot get them to stand behind you and guide your hand, real dual control.

[Mike Etheridge 1]

i have to admit to being a poor CL flyer. Despite starting my nephew on the hobby it took him to analyse why I was having so many crashes on take-off . Basically if the lines were slack on take off i was lifting my arm and running backwards when I should have kept my arm straight and have run backwards if that makes sense. I just about got the knack of it after Nigel my nephew cleared off to Bolton. I now have about 5 CL models in the loft and an own design trainer in the garage that I made over 30 years ago. Due to family commitments Nigel gave up the hobby about 8 years ago, but he sent me a picture a few days ago of his young son holding an RC foamy Spitfire so i suppose CL flying will come next ?

[Keith Evans 3]

If I remember correctly there was the RIGID WRIST published years ago in some magazine or book I once read .

It was either made from hardboard or ply.

It was the length of ones fore arm to your natural grip .It was strapped to your fore arm ,was about 6 inches wide ,with a wide slot by you hand for your fingers to grip around the HANDLE .I can draw this easily but I havn't got a clue yet as to how I can get it in this text .

A major project for next year !!!!

The whole idea was to lock your arm and wrist so the only way to guide the model was to move your whole arm from the elbow thus restricting control movement .

[Steve Porter 1]

Thanks Peter, really looking forward to flying this,will make a change from RC Planes & boats, trying to find my collection of Keil Kraft 'Bendy Props' for the PAW, might last longer than an APC?

Steve.

[PatMc]

Keith, I think the Rigid Wrist was an article with dimensioned drawings accompanying the free plan of a beginners profile fuselage C/L model called Bouncer. IIRC the model's fuselage was from 3/16 ply & the wings from sheet balsa.

I made the model, but not the RW, for my 2 youngest brothers & tried to teach them to fly C/L with it at the time. We flew it at RAF Ouston when the SMAE Nationals were held there (1965 ?).

[PatMc]

From AM Dec 1961 the Rigidrist as mentioned above :

[Keith Evans 3]

That's the one .

Thanks Pat

Keith

[Former Member]

[This posting has been removed]

[Mike Etheridge 1]

The Bouncer , I made one and it was hopelessly under powered with an ED Hornet . Later I fitted a PAW 149 and it made a lot of difference . My friend and I decided to reduce the size of the wings etc to see whether we could make it go faster which may have been the case but it became more unstable. I also made the special handle which did not overcome my taking-off problems. I have no idea what happened to the plane or handle.

Some years later I agreed to make a C/L model for a a young friend . I had lost the bouncer plan but still had the aeromodeller magazine that featured the plane so it was easy to design a similar plane and make it. The only engine available at the time was a new DC Sabre which like the Hornet was not powerful enough . However the plane did fly in the late 1970's. The young friend (Now in his 40's) found the plane in his loft recently with the seized-up DC Sabre so he gave the plane and engine back to me to get it working again. The Sabre took some time to free-up but rather than install it back in the plane, I have acquired a PAW 149 as an alternative. I just need to get around to finishing the plane and making up some 35 foot lines.

[Danny Fenton]

I am doing a Dennis Bryant 68" Chipmunk and that will be for scale control line, I have had advice from past British and US Champions and funnily enough their ideas differ. Some fly with a really nose heavy model as its smoother, others bring the c of g back to a more normal (to RC) position.

All the stuff about lead out angles is as far as i can gather correct. However the bellcrank can go almost anywhere, its the leadouts that matter. When the model is hung with an even tension on the lines, the nose should point slightly down/out to assist with line tension, also the model wing tips should be verical when hung from the lines. The front leadout at the tip, must be behind the c of g or the model will come towards you and the lines go slack, when the front line is under most tension it will be at its worst.

The bellcrank position has more to do with the leadout angle and friction it seems. Friction in the leads you don't want.

I have gathered all this info chatting to the guys at the Nats and from a doc produced by a US scale control line competitor, Fred Cronenwett. His 133 page guides is here, but it is for scale not stunt, they do things slightly differently.

There is a great and very helpful forum in the States, Stunthanger.com

Hope this all helps

Cheers

Danny

 

 

Edited By Danny Fenton on 14/11/2014 00:14:36

[Former Member]

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[Danny Fenton]

Hi Percy, I am led to believe, if you get the lead-out angles right (and make them adjustable) then hopefully you can reduce it to a point where your arm stays in its socket The trick seems to be increase the pull the stronger the wind you are flying in......

60 ft insulated lines, I am feeding PPM signals up the lines to control the throttle and flaps, so they mustn't short out

Cheers

Danny

[Steve Porter 1]

Hi Danny,That sounds like its going to get very complicated?! Think ill stick to the shorty for now, 2 lines although my control handle has a 3rd line connection for throttle if needed, Weather permitting hope to try it out on Sunday and if all goes well ill try to post some photos.

Steve