High Speed Steam Engine

[lohring]

Thanks for posting the video. Have you always used a Scotch Yoke pump drive? It's very compact. Are there any issues compared to a connecting rod drive?

Lohring Miller

 

[windy]

Thanks for posting the video. Have you always used a Scotch Yoke pump drive? It's very compact. Are there any issues compared to a connecting rod drive?

Lohring Miller

I used to use a con rod like Bobs but the Scotch Yoke is more compact I am also running pumps at 4.8 engine speed compared to Bobs 6 to 1.

There has been no problems apart from renewing the bronze block at times.

The pump rams supporting bushes are also longer.

Stroke can also be set very fine compared to a series of holes at different diameters.

 

[windy]

That's some pitch you have there on the propeller. Never seen one as coarse as that before.

Paul.

The engine has a great deal of torque once at race speed.
The start can be awkward if the prop is too deep in the water or you don't launch it level.
Amazingly it recovered from this bad launch and did 119 mph the engine was on form on the previous run it did 129 mph.
On stripping the engine found the cam for steam inlet had twisted locating key and retarded the timing also a leaking cylinder head which now has been resolved for 2014.

 

[windy]

At last Sundays runs of 128plus mph a slight problem has to be solved.
The prop UJ a simple pin and slot that was replaced for these runs is experiencing excessive wear on the slotted body 0.5625" diameter with 0.375" bore the pin out of piano wire is very good.
Have used case hardening steel, en24t, air hardening steel and others as can be seen it's like an impact wrench with the loads that's involved.
Ideas on a simple UJ design capable of taking the loads and speeds involved from a high torque engine and keeping to the dimensions quoted.

 

[lohring]

We stopped using that type of propeller drive a long time ago. Most boats use a flexible cable drive that allows a lot of variation in strut angle. The gasoline engined boats run 1/4" cable. I've never broken one, but you develop more torque. The other drive system is a wire drive. There a solid shaft running in ball bearings is slightly bent as needed. We considered running as large as 3/16" music wire on our gasoline engined boats, but stuck with the cable. Wire drives are very popular with electrics. They can have huge starting torques like steam. Check out this site for both types of drives.
http://www.rcraceboat.com/Storewiredrive.html

You will need a heavier duty version of either type. The 1/4" cables might work. They can attach to the engine with either a square or collet. I've used both and prefer the collet for ease of removing the shaft. The cable runs in a stuffing tube that can be Teflon lined. I use a piece of brass tube between that tube and the prop shaft as a bearing. See the list below for parts:
Drive Dog - http://www.insaneboats.com/mm5/merc...ategory_Code=Driveline-Parts&Product_Code=D13
Collet (engine end for Zenoah engines) - http://www.insaneboats.com/mm5/merc...ategory_Code=Driveline-Parts&Product_Code=D17
Prop shaft bushing - http://www.insaneboats.com/mm5/merc...ategory_Code=Driveline-Parts&Product_Code=D22
Cable & prop shaft - http://www.insaneboats.com/mm5/merc...iveline-Parts&Product_Code=34-WeldedPropCable

You would need a length of brass tubing that the bushing slides into for the stuffing box. A cable drive absorbs the cylinder pulsations and is pretty tough. The big advantage is the range of angles for engine and strut setup. Aeromaring makes a lot of collets for various engine crankshafts.
http://aeromarinerc.myshopify.com/collections/collets/products/nitro-flex-collets

Lohring Miller

 

[windy]

Here is the steamer in take off mode at 120plus mph at last weekends 2 days regatta at Rowden.
Picture courtesy of M Biddle

 

[AnvilJack]

Great photo, great project.

What a brilliant engineering experience.

Well done.

 

[windy]

Sadly John Benson has passed away he was co writer with AA Rayman of experimental flash steam.
He was still competing this year with his Son helping him.
His book gave me inspiration and was a Bible to me when I started building a flash steam hydroplane.
A link to his life with model hydroplanes.
**LINK**
Paul

 

[KBC]

Sadly John Benson has passed away he was co writer with AA Rayman of experimental flash steam.
He was still competing this year with his Son helping him.
His book gave me inspiration and was a Bible to me when I started building a flash steam hydroplane.
A link to his life with model hydroplanes.
**LINK**
Paul

Paul,
Thanks for the update on John, it's sad to hear of his passing, like you EXPERIMENTAL FLASHSTEAM was an inspiration to me as well.
Without the book and the help from R.Kirtley I would never have managed to get my project of the ground.

He must have been in his 90's and Alan Rayman can't be far behind, a great book for anybody contemplating a Flashsteam plant.

George.

 

[windy]

2015 test at P.E.E.M.S. club of repaired steam generator after last years burst plus checking redesigned piston.

[ame]https://www.youtube.com/watch?v=mwb6gyV2i2I[/ame]

Paul

 

[lohring]

Have you considered loading the prop by submerging it in a closed can of water? I believe Jim Bamford used this method in a simple brake dyno.

Lohring Miller

 

[windy]

Have you considered loading the prop by submerging it in a closed can of water? I believe Jim Bamford used this method in a simple brake dyno.

Lohring Miller

It has been tried in a pond but needs forced air as well to get efficient combustion.
I have a powerful leaf blower but matching air speed and prop loading needs very fine tuning.
The slightest variation on many things related to hydroplanes at 130mph upsets all the settings i.e. weight, CG, prop depth in water when running at speed, angles of skeg, engine settings and type of load on engine.
Too much load and engine plus generator can overheat.
Light load and excess fuel and water cools it all.
Matching bench tests even with a dyno to actual competition speeds and conditions is not easy.
IC engines do not have as many problems compared to high speed flash steam power plants.


Paul

 

[lohring]

I obviously have a lot to learn, but that's what makes it fun. Could you explain what changes you made to your piston? I was considering a two piece aluminum with a cast iron top, but decided proven construction was a better place to start.

Lohring Miller

 

[windy]

I obviously have a lot to learn, but that's what makes it fun. Could you explain what changes you made to your piston? I was considering a two piece aluminum with a cast iron top, but decided proven construction was a better place to start.

Lohring Miller

Dimensions of original piston is based on Bob Kirtley design after just breaking Bobs record for the following year the piston became a slipper type an increase of over 6mph with laps in the 130mph bracket.

The problem for a long running engine would be loss of lube through the uniflow exhaust ports.

I use mainly solid lubrication and get a run of about 19 100 metre laps depending on the hydroplane performance.

The 2015 slipper piston has to be tested in competition as there could be problems it is more of a design of a early F1 piston.



Paul

 

[windy]

I'm rebuilding all my damaged steam generators that because of overheating and bursts made them too short for efficient steam production.
Now having a Tig Welder decided to try to reclaim them as the stainless tube is getting expensive.
The prove of the pudding will be when they are under competition conditions with heat and pressure.
Sorry some of pictures not that clear.

 

[KBC]

I'm rebuilding all my damaged steam generators that because of overheating and bursts made them too short for efficient steam production.
Now having a Tig Welder decided to try to reclaim them as the stainless tube is getting expensive.
The prove of the pudding will be when they are under competition conditions with heat and pressure.
Sorry some of pictures not that clear.

Paul,
Do you feel that a butt joined T.I.G. weld will hold at the high temp and pressure of competition speeds.

I could only find 6m lengths of St/St tube so to get the 32ft length of coil It was tig welded but I made a sleave about 1" long and had it T.I.G. welded at both ends with the tube inserted 1/2" from both ends and never had any trouble but then I was not running at the speeds you are, I have no knowledge of what my Temps and Pressures are.

Best wishes on your quest for speed.

George.

 

[windy]

Paul,
Do you feel that a butt joined T.I.G. weld will hold at the high temp and pressure of competition speeds.

I could only find 6m lengths of St/St tube so to get the 32ft length of coil It was tig welded but I made a sleave about 1" long and had it T.I.G. welded at both ends with the tube inserted 1/2" from both ends and never had any trouble but then I was not running at the speeds you are, I have no knowledge of what my Temps and Pressures are.

Best wishes on your quest for speed.

George.

They are swaged into a top hat configuration and fuse welded into the tube outer diameter it is a test.
The 3/16 inserted into the 1/4 diameter tube was fuse welded on 3 of my original generators including the 129mph one with no problems by a race car Tig welder when using filler rod on test pieces we found inclusion into the internal diameter.
Admittedly competition will decide if OK but has been hydraulically tested to over 300 bar which is no way near the pressures of competition but heat might be the downfall?

Paul

 

[lohring]

I can't find any tables for 316 stainless tubing at temperatures above 1000 degrees F. At that temperature the burst strength is about 3/4 that at room temperature. The tensile strength of 316 stainless is around 1/3 the room temperature value at 1500 degrees and 1/50 the room temperature value at 2000 degrees. I bet the tubing failures are mostly over temperature problems since the strength falls off a cliff much above 1200 degrees.

Lohring Miller

 

[windy]

Know doubt high temperatures are the downfall of the tubing if you reduce water feed the tube at a hot spot will balloon and burst.

After a pressure fault last year the 321 tubing degraded with the intense heat and when the pressure fault was rectified tubing failed with little pressure.

Paul

 

[windy]

Had the steamer out for my first meeting of 2015 at Kingsbury Water Park trying various modifications after last years trials and tribulations.
First run did 121 mph I was personally disappointed thinking the repaired steam generator was a possible culprit or the redesigned piston not up to expectations.
On inspection found the pump drive screw had worked loose it is normally locktighted but thought it was tight enough as it is awkward to adjust the stroke when locktighted.
2nd run it did 124mph but was slow accelerating if timed a few laps later 130 mph was a possibility.
Final run under bad weather it did 127.8 mph average speed on stripping the engine found the retaining pin was missing that stops the curved cam follower rotating a part that I diligently check is tight.
For July meeting will redo that pin to be fool proof the repaired steam generator that I had Tig welded (my first attempt at stainless tube Tig welding) was successful I now have a few reclaimed ones now as spares.
The shortened slipper piston was OK apart from some carbon near the ring gap at top of cylinder bore.
The next time out I will have competition from Bobs steamer which is good for development.