Member postings for Old School

It's great when they run for the time, well done. Now onto the next one.

This what I am making, cutting the profile out on my cnc machine and putting the groove round the outside on my manual mill. Got quite a few to do both sizes.

Edited By JasonB on 22/01/2020 12:56:33

My father was a working clockmaker so the brass was probably for making wheels, too thin for plates. Towards the end of his career he made skeleton orrery clocks in batches of five.

I will order some plate from m machine.

Jason

The plate was around 2.5mm thick which I machined down to 2mm the plate was from when I cleared my fathers workshop so it was for clockmaking.

I would quite happily use plate of the right thickness if I could find it.

Oliver

Where can I buy metric sized flat brass bar I need the following two sizes.

8mm x 2mm

10mm x 3mm

i need about 600mm of each.

i have tried milling brass plate to size but it ends up bent.

I like new toys what is a collet extender for/do?

My father was a clock maker made a living making clocks from scratch everything was done in the workshop at home . He used a Sievert type torch with a couple of different sized burners. I have it now and still use it. Not into clocks but still have most of his hand tools.

I had a Terrco gunstock copying machine it would do very accurate work but it wasn't cheap. I imported it from America.

Tug

The reason for the sloping bases of some twinshaft engines is the back of the cars they were fitted in the base of the car sloped up so when the engine was installed it was level in the car. Have a look in Oliver story book.

All the engines I have used have had a "U" shaped bracket to hold the engines in and retain the engines lugs see the cobra car picture.

Perhaps it might be worth thinking about the csr it's going into before you remove the lugs.

Oliver

On the subject of engine cooling, this is a modern 1.5cc tether car engine it has no cooling fins and the car has no flow of cooling air into it other than what the engine needs to breath.

Edited By Old School on 02/01/2020 13:23:38

Tug

On your engine drawing you have a bolt hole in the crankshaft for holding on the hubs. It's common practice to use a male thread. The wheels need our be done up tightly they have a nasty habit of coming loose.

Picture of the Oliver copy wheel hub.

Oliver

Pictures as promised

Tug

Tether cars run for a relatively short periods of time, currently the distance they are timed over is 500 metres plus the time to warm up and get to speed at the end of timed run the cars are shut off.

Most of the twinshaft cars are semi scale single seat racing cars grill in the front and vent out of the cockpit, like the Oliver Tiger two five car in the picture. The car is an aluminium casting which the engine is bolted to this works as a heat sink for additional cooling.

i don't think it is necessary to change the fins on the engines, I have never had a problem with any of my twinshaft powered cars and they run for quite long periods.

I will put the pictures up later got to nip to the dentist.

Jason

Yes it is a shut off, both cars have them operated by hitting the bristles of a brush.

Oliver

A Chinese copy of an Oliver Tiger Twinshaft and a Eureka engine same as the one in the Cobra car.

Not all my cars are fast the two in the pictures are ones I run at Great Carlton track, they are a simple flat plate chassis with a tinplate toy car fitted these are probably of Chinese origin.

The engine is 2.5cc diesel of Eastern European origin of modern construction ABC liner piston schnuerle porting ball raced crankshaft of normal aircraft construction.

The wheel hubs have been extended to fit the car body.

This is a 2.5cc diesel again but a Russian copy of an Oliver Tiger twinshaft with a bit of work they go well, this one needed the piston lapping to fit the liner way too tight.

The wheels are much closer together on this car, and the plit collets go straight into the wheel hub, same a model aircraft engine.

Tug

A 2.5 cc diesel would not be competitive in today's tether car racing they were capable of around 100 mph the current world record for a modern 2.5cc tether car is around 177 mph. The car and engine were built by by Torbjorn in his workshop at home a very skilled engineer.

Oliver

Tug

The car in the foreground is a replica of Ian Moore,s Shadow it is powered by a mk3 Oliver Tiger minus the mounting lugs.

The advantage that the gearbox gives you over a twin shaft engine is that you can run much bigger tyres for example on a twinshaft diesel 58mm diameter and on the shadow 70mm diameter. Gives you more freedom in designing the car and easier push starting of the car.

The only classes that exist at the moment are for the modern cars and they are restricted to a fuel with 80% methanol and 20% castor oil, so no diesels.

All is not lost a track is being built at the BMFA,s Buckminster site, it's being funded by tether car enthusiasts, the outer running track concrete has been poured and the apron and centre will be poured in the new year. SAM 35 has been involved and it is planned that initially old timer cars will be run, diesel, spark and glow engines classes 1.5cc, 2.5cc, 5cc and 10cc.

A new thread might be a good idea.

Oliver

Edited By Old School on 29/12/2019 18:57:52

Edited By Old School on 29/12/2019 18:58:49

John MC

The crankshaft and front bearing housing has not really changed from the Nalon Viper. The performance from the engines has significantly improved over the years. In the tether car world the crankcase is still aluminium but the front housings are steel with press fit bearings C3 or 4 clearance with ceramic balls.

Various designings of front housing are in use but they all seem to have a very similar performance. I am looking forward to seeing your engine design anything new is worth a try, I will build your front end and put it one my engines and run it on the test rig to see how it compares to what I am currently using.

John

Its one solution, if it was as good as you say it would be in use in miniature high performance engines but not everything scales as we would expect.

i would be very happy to be proved wrong. As for C3/4 bearings yes they are in the bearing manufactures catalogues but try buying a small quantity no chance.