Upscaling a Hasbrouck engine

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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fredrosse
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Re: Upscaling a Hasbrouck engine

Post by fredrosse » Sun Jan 30, 2022 5:35 pm

Your boiler is rated for 25 kW (985,000 BTU/hr) & 32 kg per hour steam output (71 Pounds per Hour),so it will fall a somewhat short of the boiler requirements to get the 2-1/2 horsepower engine output. I would expect this capability to support only about 1-1/2 horsepower output, however I do not know the specifics of your boiler rating. One way to significantly increase boiler steam output is to use an engine exhaust feedwater heater, a simple, small device increasing boiler output by about 10%, heating feedwater close to exhaust temperature. My feedwater heater gives 195F (90C) feedwater temperature with an atmospheric exhaust engine.

From the FAQ Section of this Forum:

TYPICAL STEAM LAUNCH ENGINES STEAM CONSUMPTION of the Engine

Steam consumption of an engine can vary by wide margins, depending on the engine design, as well as steam inlet and exhaust conditions.

A well designed engine, with properly sized steam passages will give nominal performance. Multiple valve engines (Corliss Type), and even better, Uniflow engines, can use less steam per horsepower developed, assuming that these machines are properly designed and constructed.

Steam conditions also play here, generally higher steam pressure/temperature, and lower exhaust pressure, provides better efficiency. Steam superheat can significantly reduce engine steam consumption, as does high vacuum in the exhaust.

For small steam launch engines, these are the typical values:

Brake horsepower, ranging from 0.5 to 15 horsepower, with the great majority between 1 and 5 horsepower.

Main steam pressure, 75 to 150 PSIG, very little or no superheat

Exhaust conditions, atmospheric pressure or moderate vacuum.

Steam consumption is typically expressed in “Pounds per Hour” (PPH), and an approximate function, fairly good for typical steam launch plants, states that nominal steam consumption is 30 PPH plus 30 PPH for each horsepower produced.

For example:
A 2-1/2 horsepower steam plant would require 30 + 2.5 x 30 = 105 PPH Steam Flow. That is roughly 105,000 BTU per hour Boiler output, = 31 kW thermal

A 1-1/2 horsepower steam plant would require 30 + 1.5 x 30 = 75 PPH Steam Flow. That is roughly 75,000 BTU per hour Boiler output, = 22 kW thermal

These are nominal numbers, and a high efficiency steam plant might use only about 65% of the nominal steam consumption, while a more basic machine designed and built without efficient design could use 150% of the nominal values.
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Re: Upscaling a Hasbrouck engine

Post by fredrosse » Sun Jan 30, 2022 6:07 pm

Your proposed boat, about 19 feet waterline length, one ton (2240 pounds) displacement at slightly over 5 knots will require about 1-1/2 horsepower for propulsion. Pushing this hull faster would use power increasing as the 5th power function of speed, and around 5 knots is the practical hull speed limit.

For practical reasons I would recommend an 18 inch diameter x 22 inch pitch propeller, running at about 375 RPM. The Hasbrouck #10 engine is capable of this output at 375 RPM, using the parameters provided in the last few posts, and this is close to your boiler's output capability. This also assumes adequate engine steam port sizing for this proper RPM, but I do not have details here.

You can play with the parameters provided in the FAQ Sections of this Forum to hone in on the design. In My view I would only increase the size of the #10 engine to about 1.5 x the design power, which is 1.144 scaling factor dimensions, giving 2.58 inch bore x 3.43 stroke. 1-1/2 real horsepower at 375 RPM, direct propeller drive. The original size Hasbrouck #10 engine could also provide this performance without scaling up, but if you are building the engine, I would recommend scaling up by about 15%

Good luck and best wishes for your project.
Last edited by fredrosse on Mon Feb 07, 2022 12:47 am, edited 1 time in total.
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Re: Upscaling a Hasbrouck engine

Post by NorwegianOlav » Mon Jan 31, 2022 6:34 pm

Thanks a lot to everyone for their input! :D

I seemingly I have quite a lot to learn! I am very happy I found this forum. Haven't found a single steam launch interested person in Norway to discuss this about.

I have nothing to add to all the calculation that have been made in this thread. But I do am confused to why Mora Marineteknikk (manufacturer of my boiler) recommends a 5 HP engine to the boiler I have chosen. Seems really odd, like if they are calculating HP in a different way in Sweden.. On their site (Its Swedish) you can see their boilers under "Ångpannor" and machines under "Ångmaskiner".

Be certain I will return with more questions when time comes..!
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Re: Upscaling a Hasbrouck engine

Post by marinesteam » Tue Feb 01, 2022 7:40 pm

If your not already a member of the SBA (Steamboat Association of Great Britain). I would suggest becoming a member for the purpose of being able to access the register. I find it very useful to be able to check design numbers against existing, operational steamboats. For example, John Winn's Chimera is a bit smaller than what you are looking to build but the boiler is about the same output wise (if I have followed the thread properly). Use this data to extrapolate the engine size to a single and bump up a bit for the increased hull length and I think you would be in the ballpark. Also go through the register and find similar 19' hulls and see what the boiler and engine combos are to compare against your equipment.

You would also get access to the membership list which lists 5 members in Norway.

Cheers

Ken
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Re: Upscaling a Hasbrouck engine

Post by fredrosse » Wed Feb 02, 2022 4:58 am

One of the most typically exaggerated numbers I see in my many years of engineering practice is the horsepower of an engine. The published number is almost always higher than truth. From the calculations performed below, the engine described on the website you mention (Mora Marineteknikk) is more reasonably described as a 2.5 to 3.0 horsepower engine if using main steam at 9 Barg (130 PSIG). The boiler described on the same website however can only support about 1.7 horsepower engine output. That is OK, because the hull you are considering will be able to comfortably cruise at a little over 5 knots with this horsepower. The basis for these conclusions is detailed below for your review if you wish:

From the website information, the described boat, 5.5 meters long, 1.65 beam (18ft x 5.4 ft) has a maximum speed of 5 knots, with the boiler suitable for about 1 ton total displacement. The boat is driven with the 25 kW boiler (85,000 BTU per hour), supplying steam at 9 Barg (130 PSIG) to the 90mm bore x 82mm stroke (3.54 x 3.23 inch) steam engine, driving a propeller 500mm diameter x 700mm pitch (19.7 x 27.5 inch).
Using this data, and assuming a propeller slip of 25%, the engine rotation is calculated to 290 RPM. All of this is very close to the data generated in my calculations of performance in previous posts here, except I had assumed a smaller propeller pitch, with a higher RPM.
The website claims 5 horsepower for this engine, which I suspect to be a very exaggerated number. Using the classic PLAN/33,000 = Horsepower, and assuming 5 HP @ 290 RPM, the Mean cylinder pressure required is 107 PSI (7.4 Bar) which is a number far too high if one has main steam pressure of 130 PSIG (9 Barg). The engine Mean Effective cylinder Pressure is 82% of main steam pressure, which is far too high for reasonable economic engine running.
Reasonable engine BMEP (Brake Main Effective Pressure) for a simple engine should be about 40% to 50% of the main steam pressure, as shown in the FAQ section of this forum. Using the reasonable BMEP for this engine at 290 RPM, the calculated horsepower capability is 2.4 to 3 horsepower, which is a more reasonable result for the website engine.
To get 2.4 horsepower from the website engine, you need enough boiler capacity to produce about 100 Pounds per Hour (PPH) main steam flow (46 kg/hr), according to this website’s FAQ Section. However the boiler of the website is stated to produce only 70 PPH (32 kg/hr), which would only support about 1.68 horsepower
Compare this steamboat power plant, at 1.68 horsepower capability to the horsepower requirement I calculated in post (Jan30, 4:29PM) of this forum thread at 5.3 Knots = 1.75 HP, 5.0 knots = 1.50 horsepower is required.
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Re: Upscaling a Hasbrouck engine

Post by fredrosse » Wed Feb 02, 2022 6:14 am

Now to go back and examine the scaling of the Hasbrouck No. 10 engine to power your boat (which is very similar to the boat described on the website (Mora Marineteknikk), as well as the boat I had assumed for the calculations on my Jan30, 4:29PM post.
My recommendation is for a scaling factor of the Hasbrouck No. 10 Engine dimensions as 1.125, or slightly larger if you wish, running at 300 RPM, 9 Barg (130 PSIG) Main Steam Pressure, giving 1.7 Horsepower. 5 Knots speed, use a propeller of 27.5 inch pitch (700mm).

Ray Hasbrouck, 2003
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Re: Upscaling a Hasbrouck engine

Post by DetroiTug » Wed Feb 02, 2022 12:59 pm

I ordered a set of plans for the Hasbrouck #10 engine from Ray back around 1981? They were like $7 and they came with a photograph of a completed engine and a letter from Ray thanking me for the purchase and to please send progress pictures. Never built. Still have the packet somewhere. Found his ad in Popular Mechanics.

I think the theoretic engine hp ratings are based on what the engine is capable of delivering with an appropriate boiler. Without a boiler an engine is 0 hp. It is true that sellers tend to exaggerate the output based on simply pressure and not PPH production. That HP rating likely originates with the designer of the engine and then the boiler numbers get trimmed by the seller to fit in a realistic application i.e. 250 psi max hobby use.

Ron
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Re: Upscaling a Hasbrouck engine

Post by NorwegianOlav » Wed Feb 02, 2022 8:39 pm

marinesteam wrote:
Tue Feb 01, 2022 7:40 pm
If your not already a member of the SBA (Steamboat Association of Great Britain). I would suggest becoming a member for the purpose of being able to access the register. I find it very useful to be able to check design numbers against existing, operational steamboats.

Thanks Ken, that sounds like a good idea. I have seen their site but not the register. Will definitively check it out!

fredrosse wrote:
Wed Feb 02, 2022 6:14 am
Now to go back and examine the scaling of the Hasbrouck No. 10 engine to power your boat (which is very similar to the boat described on the website (Mora Marineteknikk), as well as the boat I had assumed for the calculations on my Jan30, 4:29PM post.
My recommendation is for a scaling factor of the Hasbrouck No. 10 Engine dimensions as 1.125, or slightly larger if you wish, running at 300 RPM, 9 Barg (130 PSIG) Main Steam Pressure, giving 1.7 Horsepower. 5 Knots speed, use a propeller of 27.5 inch pitch (700mm).

Ray Hasbrouck, 2003

Thank you very much Fred for all you're replies, appreciate it! This thread have answered many question for me. Machining and engineering is at the moment just a new hobby I have started with during the pandemic. On a daily basis I work with post-production on film and television, which is quite far from engineering.. But I do have a great interest in learning more of it. I have studied technical drawing and CAD modeling, which will come in handy during this project.

dampfspieler wrote:
Thu Jan 27, 2022 7:09 pm

To broaden your knowledge of a HASBROUK #10 you can check out this thread where I show my modifications to the design to come up with a smooth running and low steam consuming engine.

Best wishes
Dietrich
Thank you Dietrich, I certainly will have a look at you're work! Looks superb.

Best wishes
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Re: Upscaling a Hasbrouck engine

Post by NorwegianOlav » Sun Feb 06, 2022 9:19 pm

fredrosse wrote:
Wed Feb 02, 2022 6:14 am
... use a propeller of 27.5 inch pitch (700mm).
So for example an 3 x 17 x 26 prop. would be adequate? Or would you recommend an 2 or 4 blade prop?

Olav
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Re: Upscaling a Hasbrouck engine

Post by Kelly Anderson » Sun Feb 06, 2022 11:10 pm

cyberbadger wrote:
Thu Jan 27, 2022 2:41 am
Somehow I don't know how that calculation can come out to 5.

Here is an actual example of a PLAN calculation of a 2 cylinder double acting engine (1902 Toledo)
RPM = 220
200 PSI Boiler Pressure
3" Bore
4" Stroke

You could try to increase the RPM for example, but depending on the size of the propeller and any gearing you might have in between, a large propeller (18"-21" diameter) will limit your max rpm. The faster I spin my prop, the bigger the load on the engine. I am not able to run my engine as high as 400rpm, so putting 400rpm into PLAN will yield an implausible result.
Sounds to me like you answered your own question regarding horsepower. Holding the engine back to 220 RPM is of course going to reduce the HP by about half compared to the same engine when allowed to run are a maximum speed of 500 RPM, which is common for engines with a 4” stroke.

In my experience most cruising is done with the engine running easy at about around 300 to 350 RPM. There are many examples of Elliott Bay hulls powered by 3”x4” single engines with Elliott Bay 20”x30” propellors that match the above performance. If your engine isn’t able to achieve 400 RPM, I would guess that your prop is grossly over pitched or has way too much blade area for your hull/engine combination.
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