Flash Steam tethered hydro's by Stan Poyser cont

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'Phoenix' ‘A’ & ‘B’ Class Flash Steam Tethered Hydroplanes (cont)

By Stan W Poyser.

Photo courtesy Jim Free

In 1991-2 design was started for a ‘B’ class flash steam hydro in an effort to increase the existing ‘B’ class flash steam record of about 60 something mph. The ‘B’ class engine embodied several departures from the original ‘A’ class unit in order to be lighter and to improve the construction. Every engine/boat builder incorporates their own interpretation of how it should be done, at the same time they should look at the competition and listen to their contemporaries, as they may have tried the proposed changes without success. With this in mind the original concept was maintained i.e. the valve-actuating cam mounted on the crankshaft, but the pump drive transferred to the forward end of the engine and driven by the crankpin. In addition, the drive gear would be machined to provide infinite adjustment to the pump stroke, as opposed to the time-honoured disc with a series of offset holes to facilitate adjustment.

At this point I feel I should inform the reader of my passion for machining metal, I find it to be satisfying to transform a solid chunk of metal into an operational component. During the design of the engine I decided that all major screw threads would be screw cut on the lathe to ensure concentricity, accuracy of thread form and correct alignment of components.

The engine is of conventional construction with a bore of 1 inch and stroke of 5/8 inch, which gives a capacity of a little over 8cc. The crankcase is machined from solid Dural, as are the crankshaft bearing housing, front crankcase cover which also carries the water and fuel pump drive gears and bearings. The crankshaft is machined from a lorry half shaft scrounged from the local garage and the crank pin is 3/8 inch dia. HSS tool-bit pressed into the crank-disc. The con-rod is machined from titanium and fitted with a phosphor bronze little end bush with a needle roller bearing fitted to the big end running on the tool steel crankpin.

Anatomy of a record breaking 'B' class flash steam hydroplane engine.

1 Steam inlet to poppet valve.

2 Oil feed to valve chest.

3 Displacement lubricator.

4 Pressure feed to lubricator.

5 Exhaust from cylinder.

6 Hand water 'priming' pump.

7 Water pump feed to steam generator.

8 Fuel pump feed to burners.

9 Fuel and water pumps.

10 Adjustable scotch crank.

11 Reduction gear for pump drive.

12 Fuel and water feedpipes.

The cylinder barrel I machined from mild steel with a mehanite liner. Six exhaust ports are equi-spaced round the barrel at bottom of the piston stoke to provide the uniflow exhaust. The exhaust steam is collected in a steel jacket surrounding the cylinder, and then discharged to atmosphere via a silencer, which reduces the noise level to an acceptable level.

A hydrostatic lubricator provides lubrication to the valve and upper cylinder and, to date, this system has not failed under normal working conditions. Lubrication to the internal components e.g. conrod, crank pin, crank shaft bearings, pump drive and cam is catered for by ‘splash’ lubrication from oil within the crankcase.

The monotube boiler and burner arrangement on this model consists of 18ft. of ¼ inch dia. x 20swg stainless steel tube formed into a coil with the burner vaporizing coil formed from 3/16 inch dia. x 20swg stainless steel tube positioned inside the boiler coil. The whole assembly installed inside a .010 thou stainless steel casing. There are three burner nozzles mounted onto the front end of the boiler wall, the nozzles carry the mounting for the jet block which houses the three burner jets. The outlet end of the casing is formed to an upward swept opening to provide discharge of burnt gases from the burners.

During the running of the A class boats, severe burning and scorching occurred in the boiler area of the hull due to the removal of insulation from the boiler casing to stay within the 16lbs weight limit for the class.

With this problem in mind it was decided to construct the new hull from 24 swg aluminium, which presented a few difficulties in arriving at a reasonable shape and making the hull watertight, while at the same time keeping within the weight limit of 8 lbs for ‘B’ class steamers. All joints were coated with Araldite and riveted, which was a messy undertaking, but the completed hull looked reasonably good. Stress points were reinforced by double plating the areas concerned, and the all up weight came in at 7 lbs 14 ozs.

Phoenix 3 had its first outing at South Cerney in 1993 and recorded a speed of 56mph. Gradually over the following two years this was increased to about 75mph by making adjustments to the engine, pumps, planning angles and burner jets. The greatest problem was to make a propeller that would suit this hull-plant combination. Eventually the hull of Phoenix 3 suffered from metal fatigue, with cracking occurring at the sponson attachment points and engine bearers, so in the interests of safety was withdrawn from racing at the end of 1995.

Phoenix V in 1997, just after launching on a run.

The next hull followed normal construction being built on plywood frames with ¼ sq birch stringers and clad with 1/32-inch marine plywood. In order to reduce the scorching problem an increase in permitted weight to 9 lbs was requested and approved, this change enabled the hull to be ½ inch wider and 3 inches longer improving the airflow around the boiler, which reduced the burning problem. Speeds started to move upwards and on one occasion at Farnborough five consecutive runs were recorded in excess of 85mph. At the St Albans International regatta on August 2^nd 1998 a record for the class was established with a speed of 96.6 mph (from this point onwards things started to go downhill).

Stan and son Steve at the 1998 Amiens International.
They gave a demonstration run as B Steam is not run in competition on the Continent

The red cord seen towards the left of each photo is an elastic 'bungee' to aid the launch of the boat.

The start of the 2001 season prompted me to try a different hull shape, this was to be half round in section on the underside tapering to a pointed nose in an effort to spill air build up under the hull and reduce the possibility of lift at high speed which had been in evidence on the previous hulls.

.........This was the seventh boat in the 'Phoenix' series but never named.

Photo: Jim Free

Following a number of poor runs during 2001-2003 it was decided to take this hull out of use and think again about the future. However, age and physical constraints were beginning to creep up on me, and it was reluctantly decided to end active power boating, sell off the workshop equipment, and move to more manageable living accommodation.

Reflection.


Flash steamers by their very nature have a limited life span. 'Phoenix 6' is the only boat of the series that has survived complete.

Between 1990-92 six first places and nine second places were confirmed at MPBA regattas for the ‘A’ class model, with the highest speed achieved being 86 mph. From 1993 to 2003, I achieved 23 first places, one second and one third place at MPBA regattas with the ‘B’ class model, the highest speed being 96.6 mph.

Right: Stan at Farnborough in 1997, photo by the late Vic Collins

A fair amount of test runs were made on the Bradwell pond in Essex, and my personal diary of events show the speeds to be generally between 85-90mph. The magic 100 mph eluded me. I think in fairness it should be observed that the number of first places with the ‘B’ class model came about because no other steamers in this class were in opposition. I was challenging myself in order to raise the performance of the models.

In the late 1980s when my interest was resurrected Stephen renewed his involvement, and was successful with 10cc OPS engined boats recording speeds of 110-120mph on several occasions. Steve's two sons Andrew and David also started competing during this period and won prizes at the ages of 12-14, running in the novice class. As the years advanced, they both became engaged in more 'normal' teenage pursuits, and while still interested do not participate.

Steve has continued to run 10cc and 6.5cc boats, keeping up with the front-runners in both classes. With the recent introduction of 7.5cc engines, he now runs two boats in this class, and in conjunction with Terry Everitt was responsible for the construction and placing of the tripod in the lake at Althorne.


Four generations of the Poyser tethered hydroplane dynasty. From L-R: Harry (Pop), Stan, Steve, Andrew and David

During the 60 odd years of power boating I have had the pleasure of meeting some first class model engineers some of whom have recorded their trials and failures in the pages of the Model Engineer. I refer with admiration and respect to Messers Cockman, Pilliner, Bamford, Jutton, Benson, Rayman and Kirtley. To readers who seek more information on the subject of Flash Steam, I recommend the following publications: Flash Steam by E T Westbury, and Experimental Flash Steam by J H Benson & A A Rayman.

<Back, Forward to the Poyser Collection of flash steam motors >

OTW is extremely grateful to Stan Poyser for preparing this very detailed article and supplying relevant photographs. Although now retired from competition Stan maintains an active role as President of the Hydroplane Club.