Hasbrouck #7 Double Size.

[VANYA]

Hi.

I am new to this forum but want to ask if the Hasbrouck #7 steam engine can be constructed at 2 or 3X the original model size so as to make it suitable for a small ( 11 or 12 foot two person ) live steamboat.

I need a 1HP engine, bigger than a Stuart #4 but smaller than  ST 5A.

I do not have the boiler yet or the hull. I just want it very simple setup and not too heavy. I am not interested in passenger hauling but making wood or coal into steam propulsion.

Can a Hasbrouck 7 be easily made with it supposedly simple fwd/reverse method.

I welcome any input from engine builders with previous knowledge of this  engine.

Thank you.

[steamer]

Hey Vanya,

Why not drop the bore on a number 10 ?   A single will take up less cockpit space than a double.

Additionally, I would recommend nothing smaller than 20 feet for a steamboat.    The powerplant just takes up too much space.

My 25 footer is just big enough for me and my family.

A number 10 in a 20 footer would be great!

Dave

[steamer]

http://www.modelenginemaker.com/index.php/topic,249.0.html

[VANYA]

Steamer.

I thank you for your comments.

The intention of this first project can be thought of along the lines of a steam canoe, rather than an lake cruising boat or offshore big steam boat.

I have the castings for a 5A to hand, a pair in fact for a twin swan but this is too big for what I am intending. I do not want a large trailerable steam boat just yet and just want a small engine and boiler system to propel a simple boat at 3-4 mph up a still meandering waterway or around the edge of a lake. You could liken it is a small 3 1/2 inch or small tank engine loco hauling one passenger in model railway terms.

This being the first introduction to building an engine and boat, the boiler will be made by a professional but the rest I want to experience myself. I have the machinery, lathes and mill for cutting metal and the plans for a Hasbrouck #10 so I see what the big engine is like. My friend has one complete and at present I am not going there, it and the boat are too big.

I just need to know if the Hasbrouck #7 can be scaled up or the #10 scaled down.

Are there any other 1-1.5 HP engine designs out there which might be an option??

Regards

VANYA

[steamer]

The short answer is yes they can Vanya...

Dave

[VANYA]

Thanks,

That sounds promising.

Do you know much about the Hasbrouck #7 with that version of reversing.

I have ordered the #7drawings from Ron Ginger anyway, whether I build the engine or not, and at whatever size so maybe a forum member may have some knowledge of it. I know it may not be as popular as the bigger # 10 but if it works it is good.

Thank you for your immediate response, much appreciated.

VANYA

[steamer]

If you doubled that engine, it would probably work...any bigger, and I'd say go for the Hasbrouck 5.

Dave

[RonGinger]

#7 is a nice little engine for a model boat. I have one almost finished, but its been almost finished for 3 or 4 years now. In fact I started it while Ray was still alive and he sent me an extra  cylinder block he had made.

I do not think it would be suitable for scaling up to a real working engine. The piston valve part ought to be fine, but I would not do the port reversing as in the model. Some external valves might work.

But as Dave said, I think #5 is my favorite engine for a small launch, with #10 second choice if you want only 1 cylinder. However, a lot of guys seem to like the #8 V-twin. To me V engines are IC, not steam, but thats just my view. Any of these were designed by Ray to power boats, and many dozens (hundreds?) have been built over the years and proven to work. You are going to put a lot of time and money into a project like this, and unless you have the experience to design it right you may be in for a disappointment, Follow some good plans for your first boat, then later maybe design your own.

I also support Daves words about bigger boats- I built a 17ft with a #5 and it was way to small to be fun to use. (Maybe I was a bit to big) But think about sitting in the 'drivers' position, and trying to reach all the things like valves, pump handles, wood supply etc, and keeping hot things, like valves and pipes off your knees and arms. It just was not fun.

[VANYA]

Ron.

Thank you and take on board what you have said.

I have ordered the #7 drawing set anyway from you and in time will have fun making a little engine and expanding my skills.

I have read about a 1/2 size #5 build so will take a look at that as a place to start.

Can you tell me please, is there a formula for estimatimg the power output of a steam engine based on its physical dimensions and design, eg Bore, Stroke etc. I guess mathematically if you make a half size version of say a #10 it is not likely to be just half the output. Would I be correct there??

Lots to learn for me.

VANYA,

New Zealand

[steamer]

Ron.

Thank you and take on board what you have said.

I have ordered the #7 drawing set anyway from you and in time will have fun making a little engine and expanding my skills.

I have read about a 1/2 size #5 build so will take a look at that as a place to start.

Can you tell me please, is there a formula for estimatimg the power output of a steam engine based on its physical dimensions and design, eg Bore, Stroke etc. I guess mathematically if you make a half size version of say a #10 it is not likely to be just half the output. Would I be correct there??

Lots to learn for me.

VANYA,

New Zealand

Yes....half size is not half the power...

IHP = PLAN/33000   

P= MEP  in psi
L=stroke ( in feet)
A= Piston area....becareful....if it's double acting!  ( in square inches)
N= RPM

P for all intents and purposes will be the same regardless.
If we say....a #10 is 2 INDICATED Horsepower....solve for P

(2.0 /(2* (3/12 x (3.14159*(2.25**2)/4) x 400)*33000)= 83 psi  with a boiler pressure of 125...that sounds about right if your pipes are good sized

Now you have a stake in the ground for MEP.    Mess with the bore and stroke to get 1 HP = 33000 ft lbs/min

You will find it is not half....

In Round numbers.....a 2 x 2.25 single, double acting...so not that much smaller than a #10.

Dave

[VANYA]

I thought it might be like Quantum mechanical theory.

And they did the calculations way back when without Mr IBM.

This is interesting stuff.

Is there a good internet site that goes into this sort of stuff, the mathematical theory, or is it in the books of old??

Thanks.

[steamer]

"The Thermodynamics of the Steam Engine" by Peabody....do a google book search...

Dave

[steamer]

I thought it might be like Quantum mechanical theory.
.

Nope...just basic Mechanical Engineering......

[mklotz]

It's straight-forward freshman physics...

power = energy / time = energy per stroke * strokes per minute = stroke energy * rpm
energy = force * distance = piston force * stroke
force = pressure * piston area

power = pressure * area * stroke * rpm

The 33000 arises from the use of the Inferial system of measurement.  [1 hp = 33000 ft-lbf/min]

In double-acting engines the effective area of the piston on the return stroke is reduced by the area of the connecting rod.

My STEAMHP program will do the calculations for you if you're intimidated by the arithmetic.

[steamer]

To say nothing of making sure your valve cut off is appropriate for the engine...as that affects MEP.

If you have Ray's drawings, the timing is easily determined.   I would suggest using the same cut-off's he used for a marine application.

Nice Program Marv!

Dave