Member postings for Windy

Hi Meyrick, was told it would be supersonic by a friend who has just done nozzle tests on his full size flash steam generator.

We are both going down similar paths one miniature the other full size.

Ear defenders required, hope the neighbours are out its bad enough running the piston engine.

Windy

Edited By Windy on 14/02/2010 14:48:32

Edited By Windy on 14/02/2010 14:50:50

Thanks Stewart, a very useful link as was mentioned there are other ways to drill very small holes.

As one member of that link said (I need to drill 0.004" holes, and I think the recommended speed is around 95,000 rpm to keep the drill bit rigid enough without having to worry too much about the pressures that need to be applied for it to drill thru the piece part, drill bit speed is the secret to small hole drilling.)

To do it this way I would have to make a high speed-drilling spindle.

All the nozzles have now been done and have just the test stand to finish.

Hopefully next week there will be a test session to check pressures on combinations of nozzles, temperatures, speed of pumps and quantities of fluids used etc.

I have found that keeping a video record of testing has been very useful as sometimes with all the action of bench testing which is only for a limited time I can miss things that could cause problems when in competition.

Edited By Windy on 14/02/2010 10:05:27

Back again.

V8Eng mentions the gtba and I found them very good at giving practical advice.

I forgot to mention an article by D.H.Chaddock (21 December 1950) about a turbine blade copying attachment and another one by L.K.Blackmore (ME 31 January 1957) on turbine blade cutting for an experimental gas turbine.

The L.K.Blackmore attachment might be more suitable for your turbine, if you require the article I could send you a copy.

Edited By Windy on 11/02/2010 20:04:37

Hi James.

An old book that MAP used to sell (ISBN 0 85242 712 3) Model Boat Propellers has a chapter on ways to make marine props simply, also ways to calculate the various angles etc.

It does not answer your question how to mill one but gives the basics of design.

Another very old one The Book of Modern Engines has a volume devoted to all types of turbines

Edited By Windy on 11/02/2010 17:00:08

Edited By Windy on 11/02/2010 17:01:39

Hi James, I make 4"Ø 2 bladed props out of the solid for my hydroplane out of high tensile steel.

If you have an idea of the shape of the blades and the various angles you could machine a series of straight blades.

Set the blank at the root angle of the blades and use a cutter with a rounded end so no sharp corners. Using a dividing attachment mill the number of parallel-sided blades required making sure they are a bit longer than required.

Draw a diagram of the propeller, decide the pitch and measure the angles at various radiuses.

Make some sheet metal templates of the various angles.

Then twist the blades with a suitable tool checking the angles with the templates.

When satisfied turn to the diameter required and with rotary burrs, files etc. create an airfoil section to the blades.

You could set the blank at the angles required on a rotary table and go in steps with a round nose mill but that is very time consuming and will still have to finish by hand.

The material you use will have to be something that can be twisted without cracking.

Some of the turbines are cast or edm.

Hope this might be of some help.

Windy

Edited By Windy on 10/02/2010 13:46:20

Edited By Windy on 10/02/2010 13:46:58

Thanks Chris for the reply, Dag Browns article is very interesting.

You can get some very small carbide drills that the electronics industry use but they are as you say very brittle.

What I am making is a set of converging-diverging nozzles for a test rig to check if my steam generator will be adequate for my turbine, a problem the full size steam record car had.

I do step drill the nozzles then ream with a homemade taper reamer 0.1044ӯ to 0.015ӯ a bit like an injector.

If the small hole is not dead centre with the step-drilled holes the reamer suffers it is also in hexagon bar.

If I could trust the hexagon bar to be concentric it would be reversed in the chuck and the 0.02ӯ would not have to be as deep?

There are only a few more nozzles to make then I will be having a test firing, have been told that the steam from the nozzles can be very noisy and I will probably need ear defenders?

Windy

Edited By Windy on 10/02/2010 03:46:00

Edited By Windy on 10/02/2010 00:07:45

Edited By Windy on 10/02/2010 00:09:11

Edited By Windy on 24/01/2010 15:26:47

I must thank the Editor and All the contributors for an excellent magazine. I have just received No.4367. The mixture of articles is very good, as an amateur it is pleasant to see scratch built static scale models as well as fully working ones. The I/C Topics I found fascinating and the various steam powered model builds equally so. Addicted as I am to speed related machines both model and full-size I wonder if someone would write an article on performance tuning of model I/C racing engines. As there are some motorcycle enthusiasts amongst our model engineers one of my locals will be attempting to break the World Land Speed Record on two wheels hopefully in 2010 with a streamliner powered by a V 8 that has Hyabusa top ends, The record to break is 367.382mph set a few months ago by Denis Manning’s streamliner with a homebrewed V4. Thanks David for a great magazine and Website.

Windy

Edited By Windy on 13/12/2009 19:12:12