Taylor engine castings

[Mike Rometer]

A long, long time since I studied that stuff at tech school Mike, but that works for me.

It's an odd concept from the beginning as there never was such a thing as a standard horse.

[Metaltrades01]

Yes Mike I understand and agree with all you have said, and one can never give too much information

The power output from the piston to the end of the crank is obviously reliant on how the engine is engineered/designed (and the build accuracy) , assuming that both of these are done within good practice, i would have thought that their would be an (approximate) factor that could be used to work out the power at the end of the crank.

Martin

[Lopez Mike]

I think that Watt was the first person to come up with an estimate of the useful power of a horse as a way to rate his engines. As a matter of mild interest, a horse can put out many horse power for shorter periods of time. The 550 ft. Lbs. per second was based on a full day for a horse doing some sort of fairly continuous work I believe. World class bicyclists have put out around one H.P. for an hour. Athletes running up short flights of stairs for a few seconds can put out over ten H.P. It's simple to measure the weight of the person and the height difference and the elapsed time and do the arithmetic.

As far as coming up with a ratio of b.h.p. to i.h.p., good luck. The pressure on the piston is not constant during the stroke. The geometry of the con rod and it's angularity are surprisingly complex. Our engines have variable valve timing. Horrid problem. I stand by my advice about experience and claims. The only numbers I've seen have been for fairly large engines.

Unless one strays too far from common practice, most boats perform quite well. Maybe some experimenting with the prop after things get sorted out. I went from an 18 x 20 to an 18 x 24 with an engine rated by the builder at 5 h.p at 500 rpm. I can reach 485 r.p.m. at full snort.

The things that are much harder to predict are whether the engine and boat and motor mounting will all work well together to produce a smooth and relatively vibration free cruise speed. My boat has room for much improvement in this area at higher speeds.

[steamboatjack]

All the above is ok,
I made a prony brake for the Elliott Bay triple but the wood blocks got over heated very quickly, you need some form of cooling. I have toyed with the idea of making a torsion meter either optical like the “Hopkinson-Thring” or similar. Modern torsion meters are of course electronic using the strain gauge principle, I am waiting for number one son to think about it! With a torsion meter you would still need some way to load up the engine, probably a large electric motor is best, “braked” electrically, not my field.
Any way the answer the question the difference between indicated power and brake (or shaft) power is known as the mechanical efficiency, in other words losses between the two as explained above. This of course is widely variable and is significantly higher with a slide valve engine than with a piston valve one due to the friction load of the slide valves.
Other factors are bearing friction, piston ring friction etc. etc.
The losses I would take a wild guess, at about 15% of the indicated power for piston valves and 20% for slide valves but it is only a guess.
Regards
Jack

[Lopez Mike]

I wondered about those drawings I used to see of Prony brakes with wood blocks. It looked like a recipe for smoke.

The dynamometer I used to own for I.C. engine testing used a common gear hydraulic pump. The oil ran in a closed loop through a control needle valve and a fairly large tank for cooling. It cost me more for all that oil than it did for the used pump.

The pump was free to twist a bit on its axis (flexible hoses and two pillow blocks) and was constrained by a common spring scale hooked to the pump with an arm one foot long from the center of the drive shaft. I had a mechanical tach on the drive shaft and an assistant to write down the numbers. Very important as I had one hand on the throttle and the other on the hydraulic valve.

The readings I got were repeatable. The sessions were limited by engine heat on the I.C. engines though the ten gallon hydraulic tank did get stinking hot. Fifty h.p. is. after all, nearly 40 kilowatts of heat energy. Between the waste heat from the engine and the dyno heat, it was an activity for cold Winter evenings. The noise was, of course, frightful.

The data I got was of somewhat limited utility in motorcycle racing as just getting a big number often narrowed the power band such that the required number of gears produced slower laps times and grumbling from the rider.

I would love to see a power curve for a small steam plant. Not the numbers necessarily but the shape of it. Up to a point it might be a fairly linear thing. The question would be whether it would begin to level off before bits of the engine began to fly about the shop. At some point one would certainly exceed the capabilities of the boiler, of course. Not on my engine, thank you!

[Kees95]

For a steamlaunch, i'm looking for castings of a compound engine. I know the bore/stroke of the Taylor compound engine, that's perfect for this launch.

Last year I saw in this topic the castings of some Taylor engine will soon be available again. But I can't find any information about when it's available and where I can but it.

Does anyone know more about it?

[RGSP]

For a steamlaunch, i'm looking for castings of a compound engine. I know the bore/stroke of the Taylor compound engine, that's perfect for this launch.

Last year I saw in this topic the castings of some Taylor engine will soon be available again. But I can't find any information about when it's available and where I can but it.

Does anyone know more about it?

Richard Havard of the SBA is the guy who will definitely know, and indeed sometimes has full or partial sets of castings for sale. His e-mail and address etc. are in the SBA membership list (I'm a bit reluctant to post them on an open forum).

[fredrosse]

The typical definition, Indicated Horsepower vs Brake Horsepower, for very large engines in good condition would give mechanical efficiencies in the low 90's percentage points. Of course for smaller engines one would typically expect somewhat lower efficiency, probably 85% being a reasonable number for a launch engine in excellent condition. BHP/IHP = 0.85

A common slide valve with poor lubrication can seriously lower the mechanical efficiency, as well as tight piston rod packings, which can eat considerable power.

I have run a prony brake on steam engines, and running water over the wood blocks is a standard way of keeping things cool.

[ron parola]

just as a footnote Watt leased (not sold) his engines on the number of horses it REPLACED, not the "horsepower" an engine produced. Since the mines had to be kept clear of water 24 hours a day the horses ( which ran the pumps) had to be used in shifts. So indeed you may have needed only one or two horses to pump at any one time, you had to have a fleet of the darn things on standby for relieving every few hours. So an engine that may produce 2 HP was rated at 8 or so horses. So there really isn't a horse power, yeah 33000 pounds/ one minute, but a derived value based on torque, ever wonder why horsepower and torque curves ALWAYS cross around 5200 rpm (if you can spin that high) it's calculated! rp

[Oilking]

Just an FYI,
Horse power is horse power until it's boiler horse power!
There are 746 watts/mechanical HP, and 9811 watts/boiler HP! Should one size a boiler using boiler HP to match the engine HP the boiler would likely be ten times larger than you'd need. Boiler HP, commonly the USA for rating the out put of boilers in HVAC service and other industrial uses, but other than Australia and New Zealand, is not common world wide.

I've heard but don't remember the why and how the boiler HP standard came about so I'll leave it at that.

Good discussion

Dave