Bristol Radial Engine Development

[kool kitty89]

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[kool kitty89]

Umm, the Italians didn't seem to have a problem using Bristol's 4 VPC. And had such engines running arround the same time as the Hurcules and Centaurus.

 

[kool kitty89]

I think Roy Fedden must have been thinking in terms of a single valve gear drive at the front of the engine for both rows (like on many early 2-row engines and the Gnome Rhone 2-row designs and derivatives of such).

In such a configuration it would be virtually impossible to arrange a satifactory layout with 4 VPC. However, the majority of 2-row engines from the 30's and in WWII (save Gnome Rhone derivatives) had a valve drive for the rear row, basicly a mirror immage of the front row. (P&W R-1535 R-1830 R-2180 R-2000 R-2800 Wright R-2600 R-3350 BMW 801 etc)

This latter configuration should be able to be applied to a 4 VPC design without too much trouble, and as seen above, was used to do just that by Alfa Romeo.

I'm not sure why Fedden didn't consider this.

 

[tigerhellmaker]

Hi.
I search really good quality pictures and blueprints* Bristol Pegasus XX.I found that Bristol Pegasus radial engine | Aircraft Blueprint | Aviation History | Airplane Plans . Unfortunately that looks good only on wall.
I need prints in that view : top right front.

*Blueprinst and technical prints is very important for me. I try make Pegasus in 3D.

 

[razor1uk]

Quite interesting, I have spent a number of days looking for a 'head on' pic of an de-proped Mercury (or look-a-like radial) for a mech layer, so far I havent found anything that is close enough to dead on center.
I was wondering if anyone knew of any pics within their collections or contacts? Any help would be appreciated acredited; I'm planning on doing some mostly ahistorical Blenhiem skins with Macwans Template.

 

[red admiral]

Quite interesting, I have spent a number of days looking for a 'head on' pic of an de-proped Mercury (or look-a-like radial) for a mech layer, so far I havent found anything that is close enough to dead on center.
I was wondering if anyone knew of any pics within their collections or contacts? Any help would be appreciated acredited; I'm planning on doing some mostly ahistorical Blenhiem skins with Macwans Template.

I'd get in touch with the Bristol branch of the Rolls-Royce Heritage Trust. I seem to remember a bloke there scratch built a Mercury a few years ago.

 

[razor1uk]

I believe your refering to the British Aerial Museum, and their re-restoration of the Blenheim MkIV (Mark 5).
I have recently borrowed their book 'The Forgotten Bomber' and their are some great photos and the story is actually quite moving; Roy Pullam (if I spelled his name incorrectly then I don't care) was very lucky he didn't kill the other two crew, let alone any watching bystanders.
I could scan the black white 'head-on' pic, but it has exhaust stubs drive shaft protectively taped over. I'll see what you suggestion yields.

 

[kool kitty89]

Just an interesting bit of info I came across that I'd missed years ago when discussing this, but:

Nakajima Ha5 - Wikipedia, the free encyclopedia

Used a 2-row adaptation of the bristol style 4-valve cylinders with dual cams (mirroed front to back like American 2-row radials). And unlike the Alfa-Romeo 135, it saw major production and use, and it predated the 135 by several years. That said, even in its ultimate form, it doesn't seem to have been all that powerful for its displacement compared to American or other Japanese radials using 2 vpc. (and the diameter figure seems rather good, but then again, Japanese radials tended to be pretty agressive in that caregory)

So, that development may vidicate the potential bristol missed for using 4vpc over sleeve valves, but dropping back to 2 vales in general may have still been even more practical. (then again, a major strong point for the sleeve valves was performance with low octane fuel, and that advantage may have been another reason to favor 4 valves)

 

[tomo pauk]

Welcome back, kool kitty89