Low and slow

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Low and slow

Post  highpressure on Sun 02 Jun 2013, 9:19 am

Having watched Brians video of his second test run it got me thinking about my slow running speed. It has a always been somewhat difficult to get my engine to just "tick over" and something I like to see in a good engine is being able to just turn over with a whisper of steam. Now I cant get a whisper of steam, it has always been a bit of all or nothing and my regulator has a degree of travel before anything actually occurs. I have now discovered why cheers Early on the two stage regulator was dismissed and I put a nut in the front of the top section of the main regulator block to restrict the travel of the first block, having taken off the safety valve today I have discovered that the top section moves forward without uncovering any of the three small holes and then opens the main inlet, which being a reasonable sized hole gives quite a large opeing all at once, hence the difficulty in getting a slow run.

A train of thought is to file a small "V" in the rear of the main inlet hole allowing a much smaller gentle amount of steam in before the "main event" a common practice for regulators but as this involves phsically altering the main casting I dont want to do this before getting advice form people better than I. The alternative is to re-instate the two stage regulator which doesnt alter the body of the casting and can be reversed without much grief. I would add having steamed about quite a bit "full throttle" isnt called for very often so it would be interesting to see what this change will make. The "V" slot will allow a bit more opening but may never be used?

My question is... Is anyone in steam using the two stage setup at the moment and if yes how does it perform?? I have put mine back as designed but opened out the thrid "last" hole to 2mm to see how it performs and hope to have a trial steam durinng the week. If anyone has tried anything different what have you done and how has it performed?? Any one elses thoughts are most welcome. The final opening in this configuration is about half the main hole but with the three smaller holes also open in the main body so may not give much less grunt, we shall wait and see, the previous set up had just over half way but not by much.

highpressure

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Re: Low and slow

Post  lynnr on Sun 02 Jun 2013, 10:20 am

Hi Kevin

My regulator is as supplied.

Slow tick over is excellent. I think about .5 rev per second at a memory estimate.
Starting off on a rally field is very very smooth.
Ticking along at about 1/3 walking pace is easily accomplished.
Climbing a 1/6 hill in 2nd cog easily accommodated.
Dead start at 100psi on the 1/6 in 1st cog also no problem.
Scary speed in 3rg cog can be done. Actual speed not recorded.
Acceleration in 3rd outstanding and gives a bit of a shock to anyone standing close.
Not had anything to tow yet but I don't think that will be a problem. Power to weight ratio would appear to be very good. As piston area is 1/3 scale where weight is 1/9 I believe.

Still having a bit of a problem with the starter button not sealing when at low pressure and the engine running on abit. The other issue is as you say. Slow pressurisation of the chests when crank is stationary and regulator closed. On the rally field. If stopping for more than a minute. I will drop out of gear and tick over to stop this behaviour. I have re-lapped the regulator without any noticeable difference.

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Re: Low and slow

Post  IanL on Sun 02 Jun 2013, 11:00 am

Hi Lynn

You mentioned
As piston area is 1/3 scale where weight is 1/9 I believe.

For the weight it is 3cubed ie 3x3x3=27 so 1/27 of the weight

Ian

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Re: Low and slow

Post  bjwlancashire on Mon 03 Jun 2013, 4:20 am

Kevin

I know we spoke about the regulators last Friday and as you know I have a partially modified regulator so only the first holes is uncovered before the main valve slides and I get around 4/5ths of the main hole uncovered. I found that the single hole would cause the engine to hunt under load with a slight gradient, on the flat it will just about roll along. therefore, I opened the hole up a little and it seems a little better now. The fun is feeling when the main valve starts to open.

regarding slow running, I get it turning over then gradually slow down the engine pulling the regulator closed and you can achieve slow running this way.

We can all have a play at Banbury Very Happy

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Thanks for the forum info.

Post  highpressure on Mon 03 Jun 2013, 7:57 am

You see this is where this forum is a wealth of information and advice. I altered the reg back to "stock" but opened the final hole to 2mm on the top block and have just packed up from a test steam. What a difference!!! Shocked Not only can it tick over right up to 180 and just literally crawl round but pulling away is a completely different experience. No lock up at all even if you open the reg up, clearly the fact that the larger hole lets a great whoosh of steam in has an effect as it has all gone now. There is a greater travel on the reg arm before top end is felt but it is a much more controllable beast, exhibiting very similar characteristics to "Blackbeard" on the video which really is to be expected. I think this sort of useful feedback is something scratch builders cant get as readily. For those of you following on behind in the build, try the reg as supplied it certainly didnt disappoint but might benefit from slight tweaks as we gain more experience but at least the reg block can be sourced if overcooked or altered badly rather than cutting a slot in the cylinder casting which cant be altered so easily.

Tried all three gears, and for those of you like me who get the occasional "boy racer" ask at a rally "cor how fast does that go mate??" I managed 9.6 mph in top, motion thrashing quite wildly affraid . 2nd will give 5.4 mph. Used a bike computer and the wheel circumference is 2300mm for those who want to know.

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Re: Low and slow

Post  bjwlancashire on Mon 03 Jun 2013, 9:20 am

highpressure wrote:I managed 9.6 mph in top, motion thrashing quite wildly affraid

Did you get wet with oil from the big ends?? lol!

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Re: Low and slow

Post  highpressure on Mon 03 Jun 2013, 10:44 am

No I've stopped oiling them as it throws it in your face and costs money too What a Face What a Face

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Re: Low and slow

Post  Tim Watson on Mon 03 Jun 2013, 3:48 pm

Returning from the St Albans rally, my odometer recorded a top speed of 9 mph on the road yesterday. i had a steersmen and loaded waggon behind: could have gone faster, but that was certainly clipping along! The rate limiting factor is the condition of the road surface, which around St Albans is pretty poor. The steering is very steady and the wheel brake essential.

Tim

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Re: Low and slow

Post  bjwlancashire on Tue 04 Jun 2013, 1:40 am

Tim

How much free play have you allowed on the steering, half a turn, full turn??? I am nearly at one full steering wheel turn at the moment but thinking of reducing to half a turn. Spring loaded shackles would enable it to be even less but not sure where to finds such a thing. could make some with longer shackles and the appropriate springs. Seen some full size engines with this feature which allows you to adjust the free play out of the steering wheel.

Brian

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Re: Low and slow

Post  Tim Watson on Tue 04 Jun 2013, 5:22 am

Brian
Barely half a turn on the steering.
Tim

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Re: Low and slow

Post  lynnr on Tue 04 Jun 2013, 5:24 am

Same here. Barley half a turn.

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Re: Low and slow

Post  highpressure on Tue 04 Jun 2013, 5:45 am

lynnr wrote:Same here. Barley half a turn.

Are you getting confused with Barley twist brass?? Question Laughing You showmans, always up for a laugh Laughing Laughing

I have mine set as tight as is feasibly possible, probably no more than a half turn.

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Re: Low and slow

Post  lynnr on Tue 04 Jun 2013, 5:47 am

I am a highlander by god!

English is not a strong language for me. and we knew you are tight Kev Smile

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