C of G For Control line models

[Former Member]

[This posting has been removed]

[Malcolm Fisher]

I made a number of similar all sheet C/L planes based on the KK Champ and the Jasco Trojan, the main differences being the upright engine on the Champ and a "sidewinder" installation on the Trojan which I preferred. I didn't bother with any sort of undercarriage. Engines used were always diesels as I found these needed much less of a support system and at the time I started with power models the fuel cost was the same - half a crown for a half pint can or bottle in some cases. Many of these planes were flown on fifty foot lines which gave a longer circuit time so less dizziness although on windy days this could lead to loss of line tension on the upwind side of the circle.

When teaching school pupils, I made a sort of rigid wrist from a length of plastic 4" dia pipe. It was a bit heavy bit did the job and allowed the use of a conventional handle.

Malcolm

[mal brewer]

Hi Danny,

sorry but you're completely wrong with what you are saying,I can only assume you misunderstood what you have read or heard from other c/l fliers.The bellcrank position is most important to the model,as it is the pivot for the model's flight attitude. The bellcrank pivot MUST be behind the c/g,and the lead-outs should be at 90 degrees to the flight path of the model.Having said that,a small amount of of lead-out sweep-back will do no harm.The further forward the c/g,the more line tension will be generated,and conversly,the further back the c/g,the less line tension,plus of course the model becomes more sensitive to elevator.................................Mal.

[Mike Etheridge 1]

Danny,

What size of engine is going in the Chipmunk ?

Some years ago at the Sandown Park display there was a performance given by two combat teams with planes called Aerostars . The Aerostars looked like large Peacemakers and were powered I think by 40 sized glo-motors. I can remember seeing the display on a Saturday with one team dressed in red and the other blue and the planes in coordinated colours. Then the following week I was amazed to see the Aerostars on TV flying on the Wembley pitch prior to the FA cup final.

The Aerostars were eventually acquired by my nephew Nigel and his friends who were all top combat flyers . Nigel confirmed that flying these combat models certainly gave him arm ache when he flew them at Sandown Park where he introduced me to the former team manager of the original teams. The team manager explained to me that the performances at Wembley and similar places became non-viable due to insurance costs. He even claimed that some of the footballers including Jimmy Greaves wanted to fly the planes!

[SDF]

Lets not perpetuate this nonsense. Danny is completely correct and Mal is wholly wrong. It is the leadout position wrt the CofG that matters the belcrank within reason can go anywhere. It is, however, usual to try to place the belcrank such that the rake of the lines is tangential to the arc of the lines in flight. This avoids a bend in the leadouts where they exit the wing.