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Stanley 30 Hp Rocket Engine

Posted by Rick.H 
Stanley 30 Hp Rocket Engine
November 17, 2021 07:21AM
Hi Rolly,
I'm starting a new thread about this engine. You know Billy Barnes, I'm working with him to model the 20 HP Engine in the H. He has some desire to use it for a new LSR...I can't say any more. As you know, this engine is a 3-5/8 X 5 engine. According to Fred Marriot, this was best and fastest engine. Not sure if his statement was before or after the K version with the 30 HP engine. I do think, my opinion, that the ratio of the 3-5/8 X 5 is excellent for expansion and operation of a steam engine.

For all, I wanted to confirm the 30 HP Rocket engine was 82 teeth engine to 42 teeth rear-end. Also to complete a calculation on engine rpm that the wheels were 33 inch outside diameter (OD)? For some reason, I thought that the wire wheels were at 30 inch OD. Please confirm.

Also, any information on the valve and ports on the 30 HP engine, i.e. what was the steam lap, exhaust lap and the angle of advance? Then if the engine had hook-up (reduced valve travel) along with if this was favored to the larger volume of the cylinder?

Example of my 10 HP valve model.

Kind regards,

Re: Stanley 30 Hp Rocket Engine
November 17, 2021 08:25AM
I wrote an article on the 1906-7 Rocket for the Bulletin. I don’t remember what volume it was in.

In the Scientific American magazines Feb 10 1906 The body is also listed to be eighteen inches from the bottom edge to the top edge before the top cowling is attached. With these numbers sixteen feet and eighteen inches it gives one a side profile of the car body with out the curved top sections. I draw in AutoCAD and started drawings based on these numbers. The wheel diameter is obtained by the tire size The rear or driving wheels are fitted with 34 x 3-1/2 and the front wheels with 34 x 3-inch standard G. & J. clincher tires. The wheelbase is listed in the early publications as one hundred inches. But where the wheels are located in relationship to the body needed to be established. Corburn Benson was kind enough to let me do CAD drawing of his early thirty horsepower narrow frame engine. With these dimension of the engine attached to the rear end a reasonable located of the rear wheels was able to be established and hence the front wheels. In the Scientific American magazines Feb 10 1906 it is reported the radius of the back is eight inches. This is wrong, as after installing the engine to scale the minimum I could get was ten and one half inch radius to clear the cylinder block.

The original engine was a piece of junk had no hookup and the steam ports right into the cylinder head very pour steam flow passages.


Re: Stanley 30 Hp Rocket Engine
November 18, 2021 05:57AM
Rick from my experience the Model H 3&5/8 x 5" engine is very fragile. The design is really structurally a dry 10hp and the frame rod lugs on the cylinder block easily fracture.

The frame rods themselves at 5/8" are skinny. I increased the frame rods to 3/4" rear of the crosshead, made a new block with better lugs, and designed some one piece box frames to replace the original flimsy setup. It's also worth making new piston rods with the cross head block machined in one piece to avoid breakage where the threaded rear end of the rod screws into the crosshead block. My revised engine is apparently still going strong with the current owner of the car.

Stanley did not know the benefit of filet radius on either the lugs on the block or on the frame rods. The continuation of the thread on the frame rod forward through the crankshaft bearing mounts to terminate with a threaded collar is particularly horrid - the original on my H broke at this point.

Stanley were brilliant with their design concept but a bit short on the technicalities of structure and machining.Their cars were not intended to last 115 years!

Having said all that and fixed all these issues, the H is a great car and huge fun to drive.

Re: Stanley 30 Hp Rocket Engine
November 18, 2021 06:59AM
Interesting to note...the wheels turned at 1,245 rpm at 126 mi/hr. With the 42/82 gear ratio, the engine spun at 638 rpm.

Interesting the torque of the steam engine. I would venture to say when Fred was going for the LSR, he was limited by boiler pressure and had room for engine speed to increase. We all know the fundamental feature of a steam engine is that pressure gives engine speed.

I've seen articles where Fred ran at 1,000 psi. I know Billy Barnes started at 1,000 psi on the boiler for his LSR. However, from a YouTube video of Billy's run, he was around 700 psi at speed.

Mike, thank you for that info...very valuable to me. Especially when evaluating my 10 HP Stanley dry engine.
Re: Stanley 30 Hp Rocket Engine
November 18, 2021 10:22AM
The early Stanley engines had a lot of faults compared to today standards.
They were only designed for cars that went 10 to 15 MPH on dirt roads.
Not the 40 to 50 MPH most guys I know are pushing them. Some like Brent to 75 to 80
With big Red and big Green his 30 HP cars. I once roar with him holding 70 MPH. Pressure never dropped. We were on a winding country road. I asked if he ever rolled the tires off the rimes, he said not on this car.

Lots of frame rods have broke and cylinder block hubs where they connect.

I have made lots of frame rods from 4340, 108,000T. Then I started making box frames
With three plates using water jet cut plates of 4140, 95,000T.
This stopped all twisting of the frame and saved the cross heads as well.

One problem with the narrow frame 30HP was the pure design of the overall engine and the cylinder block, the steam ports came into the threaded area of the cylinder heads. The threads were ground away on the heads in the area of the steam ports.
Look closely at the photo; three threads are gone for over three inches of the circumference.

My cylinder heads and other engine castings are all cast in Ductile 85-55-06.


Re: Stanley 30 Hp Rocket Engine
November 19, 2021 11:58AM
Hi Rolly,
A quick question about the 30 HP Rocket engine. I don't think there was ever a 42 tooth rear end for a Stanley. The smallest is a 50 tooth. Not sure there is enough room for 42 tooth w/cage and spiders. Perhaps the Rocket ran with a solid axel?

Hear say says there was one 48 tooth rear end...cannot validate it.

Re: Stanley 30 Hp Rocket Engine
November 19, 2021 01:43PM
Rick where did you get the 42 tooth count from
My drawing shows a 48 tooth gear on the reared.

Most of my research was from
Racing on the rim 1907
Philadelphia inquirer 1906-07-08
Scientific American 1906-1907
Motor Sport Magazine
The Boston Globe

A graphic account of the events of 1906 and the first Stanley speed
record was written by Ted Koopman, of Motorsport Magazine who
interviewed driver Fred Marriott during 1955.

From a Marriot Interview.

The wheelbase was 100 ins. and the thread 64 in. Front tyre's were 34 in. x 3 in. and the rear 34 in. x 3-1/2 in. The body was of wood. Sills were ash and panels of white wood. The top of the body was built like a canoe, cedar ribs covered with canvas. Cockpit was just large enough for the driver and steering was done with a tiller. The fire tube boiler was 30 in. diameter and 18 in' high and contained 7,478 tubes, 33/64 in. outside diameter. Fuel was gasoline and fed to the burner at 160 pounds pressure. Engine had two cylinders, was double-acting to give four power strokes to one revolution of the crankshaft, The bore was 4 1/2 in. and the stroke 6 l/2 in. and it was rated at 30 h.p. The driving or pinion gear had 82 teeth and the ring gear 48, giving 1 ¾ wheel revolutions for each revolution of the crankshaft. Engine speed was controlled by a hand
throttle. Two sets of brakes working together on the rear axle. During the record run I carried 1,000 pounds steam pressure and figure the engine was developing around 250


Edited 1 time(s). Last edit at 11/19/2021 01:48PM by Rolly.
Re: Stanley 30 Hp Rocket Engine
November 22, 2021 06:41AM
Sorry Rolly...I was going off a previous post:
The Rocket engine was geared 82 on the engine and 42 on the rearend
The engine you showed in the photo was a wet engine that would run in oil and was stronger bolts and larger bolt pattern.
The wet engine will be a great engine for the car.
I have drawings for a box frame for the 30 HP engine as I built for the 10, and 20 HP engine.

The Rocket engine had ball bearing crosshead and the cylinder heads had all but two threads ground of in the area of the steam ports as they came in on the edge of the heads. It’s a wonder it even ran and finished the first year in 1906


I'm imputing the new ratio and using 127 Mi/hr. for the speed. New calculation for engine speed:
Wheel rpm: 1,256
Engine rpm: 735

Rolly, I have that book Racing on the Rim. It seems to be accurate in its research. It also describes the wobble Bug, another Stanley powered speedster. Another story...

Kind regards,
Re: Stanley 30 Hp Rocket Engine
November 22, 2021 11:45AM
Closes enough at 127 MPH
My excel program gave me 734.9696 eng RPM and rear end RPM 1255.561
But on Ormond Beach there most likely was some wheel slip.
So who knows for sure?
When he crashed it was estimated speed of 160 MPH by the stop watch.
That would have given him engine RPM.s of 925.937 and wheel RPM of 1581.809
Kind of hard to believe knowing how fragile the engine was.

Re: Stanley 30 Hp Rocket Engine
November 23, 2021 11:50AM
Thank Rolly...I'm in the right ballpark.

I use excel a lot at work and performing these simulations. It works well for me. My simulation is up to 3 sheets and well over 100 lines per sheet. The picture attached earlier is just the beginning. It will take me a few weeks to complete the calculations and permutations. I'm measuring and re-measuring my 10 HP Stanley to verify numbers. I use pictures and then draw lines in paint brush to figure out stuff (example attached). I believe my Stanley Engine is around a 1904. I'm working with Billy Barnes on a 20 HP version that is more challenging.

An interesting note is that the 10 horse, I can use 16th of an inch as increments. And on the 20 horse, I need to use 32nd of an inch as increments.

Here is the next query...Fred must of run with Hook-Up or some type of reduced valve travel, cut off. Do you have any information on that?

Kind regards,

Re: Stanley 30 Hp Rocket Engine
November 23, 2021 03:22PM
The engine did not have hookup built on it, it did have reverse with the Stephenson links. But that does not mean a notched bar was not in the cockpit on the control arm. Some of the linkage is on display at the Nascar museum in NC. I have never found a notched bar for hookup.


Re: Stanley 30 Hp Rocket Engine
December 04, 2021 09:01AM
HI Rick,
Can you share Billy Barnes phone number, I have been calling his shop , but it never answers......we spoke at Hershey, but I need to reach him regarding H5 questions.
Tom Lahey 904-891-8302
Re: Stanley 30 Hp Rocket Engine
December 06, 2021 07:50AM
Hi Tom,
I sent you a text message with Billy's phone number. Also, you can call me if you would like.

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