Veron Chilton DW1

oh and

The only modifications permitted from the original kit are those associated with fitting an
alternative power source, a replacement propeller (including for rubber), wheels and
moving the rear motor peg for rubber powered models

Quite correct Chris, the power can be changed from the kit original to CO2, electric or rubber as appropriate.

Two things for you Nigel,

The big advantage of CO2 over rubber is that you can throttle the engine. So if you have too much power, throttle it back. And if you still have too much torque, reduce the pitch (and/or the diameter) of the prop.

The original Telcos (made by Ticket Equipment Limited...hence TELco) were the best, the next batch issued after Micro Mould took them over were pretty useless. Micro Mould's final issue were an improvement, but they were never as good as the originals.

The pic below shows my current two motors. The one on the right is an original, purchased in Norwich in 1976. It has a bronze coloured cylinder and the adjusting plate on the front is circular with a flat for the adjusting spanner. The motor on the left is from the Micro Mould's first batch, purchased in the early 1980s direct from the manufacturer. The adjusting plate is hexagonal and the cylinder is aluminium with rather course fins. The final batch were similar to Chris's in his first posts, with finer cooling fins.

The motor on the left also shows my own mod to extend the gas capacity....

Probably a silly question but here goes, what is co2, and how does it power an engine? remember I know nothing about rc flying, boz

Boz
CO2 is a gas that results from the combustion of carbon.
It occurs naturally in the atmosphere (all animals breath it out) at low concentrations. It is pretty chemically inert (it is used as a fire extinguisher) so it is safe to compress to high levels and it actually changes its state when it is.
The result is a relatively small container can contain a lot of gas which can be used to power what is in effect a cold 'steam' engine.
This is what a CO2 powered plane uses and as it does not require a boiler or heat it is quite a light and relatively safe power unit.

Thanks for that clarification on the rules, I had them round my neck somehow. Damned if I can ever remember how to evaluate a dm2 though - is it 10cm2 or 10cm x 10cm ?!?

The one on the right is an original, purchased in Norwich in 1976. It has a bronze coloured cylinder and the adjusting plate on the front is circular with a flat for the adjusting spanner. The motor on the left is from the Micro Mould's first batch, purchased in the early 1980s direct from the manufacturer. The adjusting plate is hexagonal and the cylinder is aluminium with rather course fins. The final batch were similar to Chris's in his first posts, with finer cooling fins.

Thanks Andy I did not realise they varied so much. Pretty sure I bought mine in 1981/2 new.

Nigel I've never got dm2 either. I use ozs sq ft and a conversion ap on my phone

also two tanks in series is a pretty neat trick, I hadn't thought of that

A square decimetre (dm²) is a square with 10 centimetre sides. i.e 1 sq dm = 100 sq cm. Do not confuse it with a square decemetre (Dm²), which has sides of 10 metres.

CO2 is carbon dioxide. It's a relatively heavy gas that can be purchased over the counter in a compressed form, either as a gas source for Sodastream drinks makers or as a power source for gas powered air rifles. The CO2 motors are effectively a steam engine that operates on compressed gas rather than steam. The gas is stored in a tank, charged from a source such as a Sodastream bottle. There's normally a pin on top of the piston that moves a ball valve in the cylinder head out of the way to allow the gas to flow into the cylinder. Altering the throw of the piston in respect to the cylinder head allows rudimentary throttling of the motor.

The result is a clean power source that sounds really good in operation. The downside is that they are expensive and require a lot of maintenance. They can also be a bit temperamental. In recent years, and with the advent of reliable LiPo cells, profilers and brushless motors, electric power has taken over as the prime power source for small scale models. As a consequence, both CO2 motors and their spares are now very hard to come by.

Carbon Dioxide Boz..The bubble gas in lemonade and your beer. I think well covered in other posts.

Thanks for the detailed explanation, I had an internal combustion engine in mind, but could not figure out how it would work, it's a gas!, but works like steam!, learnt something today.

There is another reason Co2 is used as when it is compressed above 75 psi at room temperature it becomes a liquid! Those little bottles are actually full of liquid CO2. This means that even though gas is being released it will maintain a constant 75 psi until all the liquid in the bottle has 'boiled off'.

So constant engine power until all the liquid is used then it drops off rapidly, which just about the perfect power cycle for free flight!

Hi Boz found this for you www.google.co.uk/search?q=Diagram+of+a+C...1776&bih=870#imgrc=_

It's a very long time since I had a CO2 motor - can't even remember what it was - Shark? Wasn't there a way that you could give the motor just a gas charge so that it only had a short run?
Mike

That's right, simply hold the charger nozzle up while charging so that only gas transfers to the on-board tank.
In fact the power profile can be even better than Quorneng describes - because the boiling liquid CO2 takes heat from the surrounding air, it can cool the CO2 so that it boils more slowly. in effect, you can set the power high for a take off boost then let the cooling slow it for cruise. When it gets to gas it descends. At least, that's the theory
(I'm thinking that might help a scale model flight profile, it probably isn't good for a duration model)

Firewood, thanks for that illustration, now I know why I'm a truck driver, I can read maps, lol.