Bristol Hercules demonstration

14 cylinders, 39L, supercharged, 1300hp, sleeve valves.
http://en.wikipedia.org/wiki/Bristol_Hercules

Turn up the sound, really gets going around 3:30!

[ame]http://www.youtube.com/watch?v=pEbDlNeMtLM&feature=related[/ame]

 

Poor engine. Whys it hooked to the crappy trailer?

 

That thing sure has a different sound to it. Interesting, thanks.

 

I don't think I'd stand directly in line with the blades of that prop the way several people are positioned in that video clip.
.

 

Agree... wonder why... sleeve valves?


Doesn't sound like, say, a twin wasp. To my ear.

 

My father sent me a link to this animation of how the sleeve valves in the Hercules work.

This would be impressively complex today designed with the help of computers, let alone over 70 years ago.

https://www.youtube.com/watch?feature=player_embedded&v=_vrvep_YOio

Accd to wiki:
"The rationale behind the single sleeve valve design was two-fold: to provide optimum intake and exhaust gas flow in a two-row radial engine, improving its volumetric efficiency; and to allow higher compression ratios, thus improving its thermal efficiency. The arrangement of the cylinders in two-row radials made it very difficult to utilise four valves per cylinder, consequently all non-sleeve valve two- and four-row radials were limited to the less efficient two-valve configuration. Also, as combustion chambers of sleeve-valve engines are uncluttered by valves, especially the hot exhaust valves, being comparatively smooth they allow engines to work with lower octane number fuels using the same compression ratio. Conversely, the same octane number fuel may be utilised while employing a higher compression ratio, or supercharger pressure, thus attaining either higher economy, or power output. The down-side was the difficulty in maintaining sufficient cylinder and sleeve lubrication."

 

A design only Rube Goldberg could love.

Sleeve valve motors were so good, they wound up where they belong, on the scrap heap of internal combustion history. The same place mechanical Darwinisim puts a lot of dumb ideas.

Simple in a general sense = reliable. Simple a sleeve valve motor is not. While some of them made good power and the Sea Fury was a very fast airplane The later Wrights and PW's made very good power too on a lb. per hp or cubic inch per hp basis.

Sleeve valve motors with their complexity were expensive to produce and a major task to maintain. They made a Merlin look simple.

The cam actuated poppet valve was an extraordinary invention. The greatest proof of this is the fact that it has been around since the early 1700's and it is still in use on all 4 stroke piston engines. That was no accident.

Sleeve valves? A momentary blip on the radar screen of piston engine history.

 

Sure sounds like a barrel of walnuts in a washing machine when it first starts. Guess all those sliding parts take a while to warm up and get lubricated.

 

Lubrication.

Sleeve motors tended to treat lubricating oil in a total loss fashion. Round motors in general tend to be that way but sleeve valve motors have a voracious appetite for oil.

 

My Dad worked on those as an apprentice at Bristol aviation in the early 1950's, strip and rebuild etc.
Any time I would complain about something I was working on being complex I would get the "Hercules" lecture.

 

Unlike the Germans, the Brits had a propensity for producing "busy" machinery and airframes. The Hurricane is an absolute basket weaving project and some of their early airplanes kept going back to older techniques. The Spitfire and Lancaster broke the trend but some of the old ways persisted. You have to hand it to the Germans because they engineered some really simple and good stuff. I remember the comments of an NACA engineer who said that they ridiculed the DB601 because it looked like a chunk of coal on the outside with its crude castings and rather carless looking treatment to details. Then they got to the insides and changed their minds.

 

The Germans have had their share of overly complex stuff too but the 601 was quite a machine. Mostly mag castings and mag casting of the day did look crude but it sure was light and rigid. Much of the ancillary stuff was very watch like. The fuel injection alone was a real piece of work when viewed by the standards of the day.

Very few exist because unprotected mag just crumbles over time from exposure to water of any kind including just airborne water vapor. Same fate as many of the prewar Mercedes Grand Prix engines. The Germans had a pretty good handle on metalurgy at the time.


Then there would be Kruppstal.

 

Bob- WW-I was the same. Semi-skilled workers could build a Fokker Dr.I or D.VII with their welded steel tube fuselage and relatively simple wing structures (especially the Dr.I), but it took cabinetmakers and other skilled artisans to build a Sopwith Camel. Fred Murrin said he could build several Dr.Is in the same time it took to build his Camel.

Same for engines. The welded up cylinders of the Mercedes engines looked pretty crude up front, but the Rolls Royce and Liberty engines pretty much copied the cyliinder design.

 

I know about the magnesium castings of the DB601 and that is what is amazing about the ME109 in Paul Allen's collection. It has an original DB601 and I have seen and heard it fly. Distinctive sound vs. the Merlin. His FW190 also has an original BMW engine and that sure has a nice growl to it. Last summer they flew both of them on one sunlit afternoon. Wonderful!

 

I agree, Taz. The wooden airframes of things like the Camel, Pup, Spad, and DH4 were terribly intricate and work intensive. I was at the Museum of Flight today and looked at an uncovered fuselage of a Jenny and an older Boeing. Incredible intricate minutia held together by hard wire trusses that had to be " tuned" to keep everything held tight. The WW1 wing has some beautiful airplanes on display and I thought of you and Russ since there is a DR1 and a beautiful Camel there along with many other WW1 crates.

 

I cant remember if I was told or read it somewhere, but I heard something about the ministry of supply in England liking wooden planes because we had plenty of trees and lots of furniture factories. As intensive as the labour was and complicated the designs, to get performance and strength out of such designs as the wellington, hurricane, and mosquito from a wooden frame was pretty clever...not sure how well they stood up to termites though !!

 

Al Gore would have a heart attack if he saw this video..this guy is increasing the earths rotational speed! and.. probably in the wrong direction too..!!

It sounds like a bunch of large coffee cans popping when it is first fired. Cool engine.

 

Bob- I visited the Museum of Flight a few years back when the League of WW-I Aviation Historians had their seminar in Seattle.

 

The Wellington had an aluminum frame but it was built like an open weave basket with its geodesic construction. That one went the way of the sleeve valve engine. The Hurricane was two things at once; a bolted aluminum tube fuselage frame with wooden formers and stringers covered with fabric. The wings had bolted and riveted aluminum truss spars and ribs and the wing aft of the spar was fabric covered on the Mark 1. The Mosquito was skinned with a laminate of vertical balsa core and birch ply skins and that proved to be a strong and extremely smooth structure. Thermal set in concrete molds...The same thing that Jack Northrop did in the early thirties with the Vegas. The Mossy wings were built with spars of birch with spruce caps and the inter spar area ribs supported heavy spruce stringers over which was a covering of the laminated balsa core and birch skins. It was a masterpiece of wood construction that the Germans tried and failed to copy. A great airplane!