The Steamboating Forum

Dear John and Edward,

MAGNIFICENT!

I was delighted to see the engine running on the brake and with the results you achieved under preliminary conditions.

I am pleased to see that you incorporated my modification to the valve gear to move the wayshaft to port. It really makes a remarkable difference to the geometry. There is much less link jump.

It's interesting that your engine runs clockwise (from Aft) with the regulator arms close to the engine and the quadrants to starboard. Mine runs clockwise with the regulator arms away from the engine and the quadrants to port.

Any particular reason???

My engine was run on a brake on 3 occasions, the following are the results ( I wasn't able to format the table to work on the forum so you will have to juggle the figures under their correct headings):

Chest Pressures
Date RPM Boiler lbs at brake Horsepower HP IP LP Vacuum (in)
19.3.05 227 150 28 2.42 130 75 22 0
315 180 42 5.04 160 78 20 0
26.3.05 300 185 63 7.20 185 75 20 10
250 185 56 5.33 180 75 16 8
28.4.05 300 160 63 7.20 155 56 11

Here is a photo of the brake arrangement:
Here's one of the brake showing the inboard condenser:
Here's another view:
On each occasion I had some difficulty balancing a big enough fire to keep the pressure up and the need for stopping and starting the engine to tend to the burning brake. I ended up with a smallish fire and extensive use of the blower to avoid the safety blowing and annoying the neighbours. I found that the pressure dropped fairly quickly when the engine was under full load. I reckon another horsepower or so was probably there if I had been able to maintain a roaring fire.

If you can decipher the table you will see that the maximum pressure on the brake was 63 lbs at a radius of 24" giving a brake horsepower of 7.2 @ 300rpm and 185psi.

My original valve calculations gave an estimated horsepower of 7.4 @300rpm so I was very pleased with the outcome on the brake. Those calculations gave an IHP of 11.4 and I used a card factor of 0.66 to estimate the BHP.

The same spreadsheet suggests that, at my maximum revolutions in the boat of 380, the engine is probably producing about 9.5 BHP

I am looking forward to more news of your progress.

Kind regards,

Peter Cowie
Sydney
SL Witch of Endor

Peter, what was the vacuum you got on the last run on the 28th April?

Ref the comments by Peter,

I only really did the brake tests to put some load on the engine; I do not think the results are very accurate or in fact very important. What is really wanted is to get the engine in the boat and loaded up while taking a “set of cards” this is the only way to know what’s going on in each cylinder regarding particularly the valve settings and the engine cylinders can be balanced for power, if properly designed it should produce about the same IHP on each cylinder.
I have an engine indicator but this would probably suffer from “cord whip” at 400 RPM. Modern large engines now use computers to do this, measuring the pressure in each cylinder and using a devise to locate the crank position & speed they produce very accurate diagrams and log the various parameters and indicated power.
I expect somewhere out there somebody has the software which could produce a simplified version.

Weigh shaft position: Study of the drawings supplied by Elliott Bay soon showed that something was very wrong here, I suspect the following: - the weigh shaft position was put in an arbitory place mainly to suit the pivot lugs conveniently incorporated with the valve cover castings. Having drawn in the links I suspect they then realized the reversing arms would foul the links and so increased the length of the drag links to compensate, this of course throws the whole geometry out leading to a large amount of “link slip”.
It is often the case that people who should know better do this kind of thing; the weigh shaft position has to be part of the overall link geometry.
What is really puzzling is that a couple of engines have been built with this obvious error. I submitted a diagram in the old forum which shows the correct theoretical position of the weight shaft etc. which I use on all engines with Stephenson gear.
Regarding the reversing arms, EB’s publicity makes much of the independent cut off arrangements, however the angle of the adjustment slot is incorrect and I believe such items are only required on ocean going vessels I have therefore not fitted these.
The reason that my links are opposite to Peter’s is that I have assembled the engine with “open rods” instead of “crossed” I always prefer to use “open rods” this is because these allow the lead to increase when “linking up” instead of decreasing. The engine can therefore be arranged with a fairly small lead in full gear. Also “crossed rods” make the valve travel reduce considerably when linking up causing wire-drawing.
Regarding the aux. pumps these were designed and the castings supplied by Bill Lowe of the U.S.A. and are driven by a reduction gear of about 1:3, the pumps themselves are ok although air pumps should always be vertical single acting to reduce air being trapped in the clearance volumes which maybe a problem with this horizontal pump.
The drive system however was a very poor setup and has taken a lot of re-designing.

I would like to thank everyone who has admired the engine on this forum as it has taken me many hours of re-designing to get it sorted not to mention many hours in my workshop although to be fair I came to the project after the cylinder block had been machined and a few other items started.
Regards Jack

Nicely Done Jack!

.....and when is she going into the boat?....


Dave

The finished engine:

Some of us on this site are not and probably will not be machinists. Sure we may learn to turn a machine on-maybe-but we will never achieve this level! This is beyond machining,this is art! Well done! In showing us these projects it allows us to dream and learn. Upon finishing a house in a luxury neighbourhood I had a realtor comment "It's amazing what you can do with a few pieces of wood!" I found the comment humourous but I have never forgot it. So I pass the compliment to you "It's amazing what you can do with a few pieces of metal!" Nice work. Den

All I can say is WOW

What you need to do is incorporate as a "not for profit", get recognition of the engine as a "national heritage" and then apply to the appropriate government agency for funding to house it properly - probably in a 28 foot torpedo style launch with a "duck tail" stern and Almy type boiler - and in a good weatherproof and floating (no Cumbria floods for you) boat house.

That's a work of art! Amazing!

-Mike

28 foot torpedo style launch with a "duck tail" stern and Almy type boiler

We're going for 32 foot.