Author Topic: Bristol Hercules sleeve valve radial engine plans drawings  (Read 6179 times)

Online Vixen

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #105 on: March 23, 2022, 05:40:11 PM »
Sleeve valves and port timing

The Bristol Hercules, together with all the Bristol sleeve valve engines, employed the single sleeve Burt - McCollum sleeve valve design. A small crank (one per cylinder) moving at half engine speed, lifts and rotates the sleeve in an elliptical motion via a ball joint.

In the illustration below, you can see the elliptical orbit of a single sleeve inlet port (shown in green) as it passes the corresponding cylinder inlet port (shown in blue). The inlet port is opened by the sloped and vertical edge of the sleeve port and closed by the lower horizontal edge. The two exhaust ports are different; being mirror images, they are opened by the horizontal edge of the sleeve port and closed by the sloped and vertical edges. The curved back face of the sleeve port has no timing function, it's purpose is to seal the port.

The sleeve operating crank can be seen at the lower left corner of the illustration.






The relative motion of the sleeve ports and piston are shown in the series of illustrations below.

The sequence starts (extreme left) with the cylinder at the point of ignition. The Piston (shown in red) is naturally at TDC. The sleeve is also at it's TDC. All the sleeve ports are above the junk head piston rings and the combustion chamber is sealed by the solid sleeve wall and by the junk head and piston, piston rings.

During the power stroke (second from left) the piston descends to BDC while the sleeve move part way down to it's BDC position. Just before the piston reaches BDC the exhaust ports begin to open in the normal way.

During the exhaust stroke which follows; the exhaust ports are fully open as the piston returns to TDC expelling the exhaust gasses. The sleeve moves to it's BDC position. Just before the piston reaches TDC; the exhaust port and inlet ports are both momentarily open at the same time. This is the overlap period.

The induction stroke follows. The piston returns once again to BDC drawing mixture through the open inlet ports. The sleeve starts to move upwards.

During the compression stroke, all ports are closed, while the piston and sleeve both move to their TDC positions, sealing off the combustion chamber, ready for the next charge ignition. Back to the left hand illustration.






Back in Reply #62, I spelled out my views on the milder valve event timing that will provide for a smooth running and well mannered model sleeve valve engine. Not the wild 'spicy' timing of a supercharged engine, but a less aggressive, 'milder' set of valve timing events.

The final illustration shows the changes in the sleeve port size and shape which will result from the proposed changes to the port (valve) timings.

The standard Hercules sleeve port event timings (longer duration and larger overlap) are shown in red. My proposed shorter duration and lower 20 degree overlap timings would be achieved by the smaller sleeve ports shown in blue. I have included the shapes of a 30 degree overlap timing, to show the trend line.





You can maybe see how the horizontal port edges control the port open durations, while the slope and vertical edges control the overlap period. As Per pointed out earlier, You can always open out a small port to modify the timing, but it is never possible to do it the other way around

Cheers

Mike
« Last Edit: March 23, 2022, 08:51:39 PM by Vixen »
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Online Vixen

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #106 on: March 23, 2022, 06:07:35 PM »
I have now been retired for more than twelve years, following a fifty year working life. Fortunately I am still relatively fit but have definitely slowed down over recent years. As I said earlier, I have been seriously thinking about this engine and I ask myself if I have enough model engineering years left to complete this engine, as well as the other two big engine projects I have underway.

I took on this Hercules engine project on behalf of a friend who was terminally ill, sadly, he has since passed away. His family wished for his engine project to continue, I offered to help. Sadly, I realise I may not have enough model engineering years left myself, and perhaps I now need to find someone else with the skills and dedication necessary to complete the Hercules engine which would allow me to concentrate on my own engines.

If any of you would like to consider taking on this Hercules engine, then please send me a PM (Private Message) and we can discuss whats involved. Although the hardware is quite heavy, it can be shipped worldwide. This offer extends to all of our MEM members and I can extend the offer to guests and non members: However you will need to register as a MEM member in order to send me a PM.

What do you think?

Cheers   :DrinkPint:

Mike
« Last Edit: March 23, 2022, 08:05:07 PM by Vixen »
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Online Roger B

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #107 on: March 23, 2022, 07:38:50 PM »
You have collected an amazing amount of information on this engines details  :)  :)  :ThumbsUp:

I understand you thoughts on being able to complete it  ::) it is unfortunately completely outside my workshops capability. I do hope you find someone who will be able to do it justice.
Best regards

Roger

Offline MDRBM

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #108 on: March 24, 2022, 09:46:51 PM »
Wish i could take this on, but do not have the skill or equipment to do it justice, hope there is someone out there able to do so.

Online Vixen

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #109 on: March 25, 2022, 01:08:13 PM »
You have collected an amazing amount of information on this engines details  :)  :)  :ThumbsUp:
..........................

Hello Roger and MDRBM and everyone else who called in

Yes, during the long winter evenings, when the cold workshop at the bottom of the garden had little appeal, I was able to devote the time indoors to researching the sleeve valve engine, trying to understand how it works and what made it tick. It sure kept me out of mischief as Admiral Per would say.

FYI I have been contacted by a someone who is ideally placed to take on the Hercules engine. It's a small world, so I already know him. He is very determined and very capable and is a precision engineer by trade. So sorry to everyone else, but the engine will go his way.

So I guess that's the end of this chapter, it's been interesting. Thanks to all who joined me on this journey of discovery.


Stay safe

Mike
« Last Edit: March 25, 2022, 08:38:56 PM by Vixen »
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Online Jasonb

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #110 on: March 25, 2022, 01:42:03 PM »
Good to see it has found a new home, maybe the new custodian could be talked into posting an news about progress here. :stickpoke:

As I said when it came up on ME a few months back it not only needs someone with the ability but also time and a genuine interest in the subject if it is not to languish in a box for years,

Offline RReid

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #111 on: March 25, 2022, 02:40:36 PM »
I'm very glad to hear you've found a good home for that project; and that it is going to someone you know. Hopefully you'll be able to maintain some contact with it. Here's to the coming of warmer weather! :cheers:
Regards,
Ron

Offline Admiral_dk

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #112 on: March 25, 2022, 02:46:27 PM »
Good news Mike  :ThumbsUp:

And I share Jasons sentiment - that it would be nice if we will hear a bit about progress along the way  ;)

Stay safe and healthy  :cheers:

Per

Online Vixen

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #113 on: March 25, 2022, 02:59:39 PM »
Thank you all,  :ThumbsUp:

I feel I have done my duty to the family who wished to see Brian's work continue. Firstly, I have been able to progress the project a little, by searching out information and copies of the most relevant blueprints so that the missing drawings may be recreated. And secondly by finding someone with the ability to take the project forward to completion.

Live long and prosper   8) 8) 8)

Mike
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline AVTUR

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #114 on: March 25, 2022, 04:22:52 PM »
Mike

If your successor needs help from Bristol RRHT I am only too happy to oblige.

All the best with the other engines.

AVTUR
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Offline Craig DeShong

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #115 on: March 25, 2022, 10:59:00 PM »
Glad to hear the Hercules has found a new home with someone with the skills and ability to do it justice.

Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline dickymint

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #116 on: March 29, 2022, 01:41:32 PM »
Hi Mike,

It is great news that you have found a home for this project and also little sad that you would not be completing the build, I do find your build threads very informative and educational. I would one day like to build a sleeve valve engine but at this time my skills and workshop are not up to the task yet. Out of curiosity will you be continuing with creating the required drawings to finish the project and have you any thoughts on making that information available ?

Stay safe.

Rich S   

Online Vixen

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Re: Bristol Hercules sleeve valve radial engine plans drawings
« Reply #117 on: March 29, 2022, 02:40:05 PM »
Hello Rich,

I am pleased you enjoy the build threads, I like to try to weave in some technical background and a little history into the threads.

As to the drawings, I had not planned to do any more drawings for a project I am no longer pursuing. However, If the new builder needs any design or drawing assistance, I am very willing to help.

Regards

Mike
« Last Edit: March 29, 2022, 09:24:27 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.