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Old 07-15-2015, 01:52 PM   #61
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Have been sent this picture of last Sundays run courtesy of
http://www.onthewire.co.uk/
Probably 130mph plus not long afterwards it went vertical as you can see very little flame when under load a sign of good combustion.
An estimate 135mph when it took off the mods I did to the engine worked but has brought aerodynamic problems at this faster speed something I had and cured when doing 120mph it's a new ball game now.


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Old 07-15-2015, 09:37 PM   #62
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A bit of a catch 22 situation you have there, you need the aerodynamics you have now to get you through the 120 barrier, but you then need to change it by the time you hit 130, as starting out with a 130mph setting might not allow you to get to and through the 120mph barrier.

Can you mount some sort of mechanical sensor on the hull to change the aerodynamics as you speed up even further?

As you can most probably guess, and even though we have met and talked for a fair time at the midlands show many years ago about this subject, I have no basic working hands on knowledge of this type of powered hull, but I do take a great interest in their workings.

John


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Old 07-16-2015, 12:21 AM   #63
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Windy, thank you for posting, this is a very interesting hobby. Each time I read your posts I walk away with more questions, Can you suggest a site or publication that will start at the lowest level of flash steam power plants? You said that you used a solid lube, what would that be and how does it work at such speeds and pressures? Keep posting, please.


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Old 07-16-2015, 09:09 AM   #64
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Quote:
Originally Posted by Silvergoose View Post
Windy, thank you for posting, this is a very interesting hobby. Each time I read your posts I walk away with more questions, Can you suggest a site or publication that will start at the lowest level of flash steam power plants? You said that you used a solid lube, what would that be and how does it work at such speeds and pressures? Keep posting, please.


Good luck
A good starting point about flash steam is Experimental Flash Steam by Benson and Rayman the design by Bob Kirtley which is the basis of my engine with a lot of mods that Bob is trying now i.e piston design.
When I stripped my engine after Kingsbury it did do a lot of laps before VTO the condition was as if it been plodding serenely along.
Cam follower a part that takes intense loads was very good.
My 2015 short slipper piston with new ring (gap 0.003") exhalent.
Could do with new gudgeon pin and maybe big end. Making a new manifold as the intense heat when it became an underwater missile hardened it out and it smashed when tightened.

Also after on site repairs the last run the generator burst the new section I had tig welded and joint was OK it was part of the old stainless that had degraded.
the dry moly paste on the cam and follower adheres to them more than the oil, Grathos on piston, cylinder and valve guide are used as I have my suspicion moly at intense heat causes more problems.
The potential for a new record is there but from my experience of my younger days when attempting motorcycle records with my scrap yard specials in 1971 and 1974 you can never take anything for granted.
A long reply for me but will have to get back to metal munching soon as will be going to Newby Hall Classic Car Show on Sunday to drool over real cars not modern tin cans.
The motorcycle speed record bug has never left me and you never know a high speed steam motorcycle might suddenly appear on the scene.
After a local young lad of 85 wins Classic TT http://www.bbc.co.uk/news/world-euro...f-man-22201823 I remember him from my youth there's hope for me yet.
By the way I never believe in luck if machine and conditions correct you will achieve your goals.

Paul
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Old 07-16-2015, 01:36 PM   #65
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Blowing off is a problem with high speed hydros. We didn't go as fast as you, but we did a lot of testing to get to 110 mph with a similar size gasoline engine powered RC hydro. A quick fix was an airfoil on the front sponson tube. It can be deflected to give down force. Your tubes are short so you may need a spoiler on the hull as well. We used spoilers on the wing section of a sport hydro to kill the lift. That allowed the boat to exceed 100 mph. It blew off at 75 mph without the spoiler. I'm not sure our sponson design would help in a tether boat. They were designed to track straight. Below are some pictures. The last picture is a larger hydro for a 35 cc engine. Note the holes in the sponsons for different positions. The forward position shown was what was used.

My former partner, the brains behind our record, now lives in Poole. He runs a kart business, but is still interested in model and full size boating. At one time he wanted to build a steam powered boat. You might contact him at Bontoft Kart Engines. He is a great mechanic and has an intuitive feel for high speed boat design. At the least, he probably could be persuaded to watch you run.

Lohring Miller
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Old 07-16-2015, 02:08 PM   #66
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Blowing off is a problem with high speed hydros. We didn't go as fast as you, but we did a lot of testing to get to 110 mph with a similar size gasoline engine powered RC hydro. A quick fix was an airfoil on the front sponson tube. It can be deflected to give down force. Your tubes are short so you may need a spoiler on the hull as well. We used spoilers on the wing section of a sport hydro to kill the lift. That allowed the boat to exceed 100 mph. It blew off at 75 mph without the spoiler. I'm not sure our sponson design would help in a tether boat. They were designed to track straight. Below are some pictures. The last picture is a larger hydro for a 35 cc engine. Note the holes in the sponsons for different positions. The forward position shown was what was used.

My former partner, the brains behind our record, now lives in Poole. He runs a kart business, but is still interested in model and full size boating. At one time he wanted to build a steam powered boat. You might contact him at Bontoft Kart Engines. He is a great mechanic and has an intuitive feel for high speed boat design. At the least, he probably could be persuaded to watch you run.

Lohring Miller
When I had the steamer doing 120mph in 2011 here are some of the notes at that time.
Perfect 1st run, no prop jumping, sponsons just clear of the water. My fastest recorded speed of 114.91 mph. I asked how can I make it go faster? 2nd run going faster then takes off. With the help of FS convert Fred Reeve we repaired it and altered the skeg angle to try to keep nose down. 3rd run it took off again. Observers thought at about 120mph. A new dykes ring had been fitted for the previous Kingsbury meeting but had been unable to launch so think when ring bedded in it went faster. Hull has got to be repaired as it has split.

The following year 2012 canards with gurney flaps were fitted between the sponsons and were an instant success just breaking Bobs record.
2013 speed record increased to 129.33mph.
The hydro has lapped stably at 131mph at Kingsbury many times.

Might increase their area now that speeds well over 130mph are achievable there are other things that could be tried but that adds more complication which might be a step backwards

Paul
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Old 07-16-2015, 03:08 PM   #67
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What about shifting the c/g forward a bit?
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Old 07-16-2015, 06:59 PM   #68
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Moving C/G is not that simple due to engine, generator, fuel and water tanks plus the weight limitation.
In an ideal set up the fuel and water tanks would be at the C/G but then fuel flow to pumps would be limited and these type of pumps would be no use if tanks were pressurised.
Then the boat with tanks at the C/G would make it wider which is a major problem and causes a lot of lift if air flow gets wrong.
Like all speed increases new barriers have to be overcome and all suggestions are welcome.
I would like to do what some aircraft do with there fuel and distribute it in flight to get the correct balance.
No doubt the tanks are a most likely cause of the take off increasing the front canards might help to reduce lift at the cost of drag.
It's all a compromise as the full size hydroplanes with all there technology have found they regular flip.

Paul
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Old 07-17-2015, 02:20 PM   #69
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Quote:
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What about shifting the c/g forward a bit?
You need to keep enough weight on the prop otherwise the prop lift will blow the prop out. The hull acts like a wing in ground effect. This effect can be magnified with air traps (skirts) on the hull. All Mike's hydros were designed to be wings so as little of the boat would be in the water as possible. However, too much lift or lift in the wrong place causes problems.

The last picture above and the pictures below show his latest thinking. The little outboard hydro below went 86 mph with a 3.5 cc engine. At first it had too much wing area and blew off. The wing was trimmed to give the right amount of lift.

By the way, the rear wing used on full sized hydros for stability, isn't effective enough on models. Another of Mike's designs with a large rear wing is below. It is a 1/4 scale model of an electric hydro that was never built. It was over powered and went over 90 mph initially. We could deflect its rear wing up to 30 degrees with little change.

The forward sponson position helps stabilize these designs. As the wing lifts, it loads the sponsons which prevents diving. The sponsons are actually little wings in ground effect as well. When they lift, the main wing increases its angle of attach to counter. The tiny sponsons also loose lift very quickly with height. Video shows that they seldom touch the water at speed. On our boats only the rudder and part of the prop are submerged.

All wings in ground effect quickly loose lift with height. The problem is the center of lift movement. As the wing moves out of ground effect the center of lift moves forward from around 3/4 of the cord to 1/4 of the cord from the leading edge. This is what causes all hydros to blow over if they bounce up enough. We tried to use the loss of lift with height on 3 wings in ground effect to counter this center of lift movement on the main wing.

Lohring Miller
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Old 10-09-2015, 09:15 PM   #70
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At my last runs of 2015 127mph this run was with prop nearly riding on it's boss.

Photos from previous faster runs at 130mph + the prop tip is just in the water and still accelerating.

A new larger wing on front this time (told it would take off) made it stable instead of flipping.

Sponsons are off the water

Bobs large tail fins on his 120mph plus hydro has an stabilising effect on his hydro and reduced flipping with smaller ones it takes off.

Here is a video of 3 flash steamers at last Kingsbury of 2015



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