Author Topic: Bristol Beaufighter  (Read 201056 times)

Offline bustr

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Re: Bristol Beaufighter
« Reply #870 on: May 23, 2012, 01:51:03 PM »
Duxford museum has been working on getting a Beaufighter flying. A few years ago i heard they were having trouble sourcing suitable Hercules engines for it. Post war Hercules engines are relatively common but have cooling fans and exhausts that sweep back behind the engine like the BMW engine in the FW 190A. The Beaufighter had its exhausts meeting in a collector ring on the leading edge of the cowling. Not as good aerodynamically, but it did also act as a de icer. Not sure what progress has been made since then.

The Bristol Hercules used in the Beau had sleeve valves and a small army of gears to move the sleeves in time. They tended to consum oil but, were efficient engines for the time and into the 50's. The intake and exhaust ports were on the front face of the cylanders. The BMW 801D had enclosed over head rockers with enclosed push rods. The exhaust valve was sodium cooled and rear facing.

As a kid making plastic models I always wondered why the exhaust on british radials faced forward.
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This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline LCADolby

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Re: Bristol Beaufighter
« Reply #871 on: May 24, 2012, 01:00:51 PM »
As a kid making plastic models I always wondered why the exhaust on british radials faced forward.
You mean the airintake on the top of the radial right?
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Offline nrshida

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Re: Bristol Beaufighter
« Reply #872 on: May 24, 2012, 02:18:54 PM »
No he means these Dolby, the exhaust pipes, two per cylinder, which pop out the front side:-





There's a very long and interesting story behind this sequence of engines which I will all bore you with one day when you can't sleep  :old:
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Offline bustr

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Re: Bristol Beaufighter
« Reply #873 on: May 24, 2012, 02:42:30 PM »
Are those the return springs for the sleeves around the base of the cylander?

I always thought the air intake was one of the two pipes in front. Where is the air intake on a sleeve valved Bristol? Are those clamshell casings with the cooling fins clamped around the cylanders?
bustr - POTW 1st Wing


This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline nrshida

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Re: Bristol Beaufighter
« Reply #874 on: May 24, 2012, 03:18:37 PM »
There are no springs on the valves bustr, they are moved by small individual cranks (that's what the crazy gear system drives). There are also two intake ports on the back of each cylinder coming from the supercharger. Those springs hold heat shields in place.

I have some pages from the service manual somewhere around that will help. I could also type a very lengthy explanation, but it's probably best you just watch these two videos:-

http://www.youtube.com/watch?v=Liqqo8Cdb68

http://www.youtube.com/watch?v=EJcxpFTFJPA

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Offline RTHolmes

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Re: Bristol Beaufighter
« Reply #875 on: May 24, 2012, 03:23:34 PM »
this is a goodun too, 3D model of the hercules :aok

http://www.youtube.com/watch?v=_vrvep_YOio
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Offline Babalonian

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Re: Bristol Beaufighter
« Reply #876 on: May 24, 2012, 06:24:51 PM »
And I thought the Beu thread couldn't get any more awesome.  Thank you Shida and Holmes, fascinating and educational. 
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Offline bustr

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Re: Bristol Beaufighter
« Reply #877 on: May 25, 2012, 12:13:29 PM »
WoW!!

How many hours did you get on the gear gangs before a rebuild?
bustr - POTW 1st Wing


This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline Rich52

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Re: Bristol Beaufighter
« Reply #878 on: May 25, 2012, 04:39:52 PM »
Any Beau's currently flying? Wouldnt ya love spinning this around the salt air? http://www.largemodelassociation.com/keith_mitchell_bea.htm or http://www.myrcomm.com/beau/models-n-sims/models/safer/index.html
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Offline Pigslilspaz

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Re: Bristol Beaufighter
« Reply #879 on: May 26, 2012, 03:01:02 AM »
this is a goodun too, 3D model of the hercules :aok

http://www.youtube.com/watch?v=_vrvep_YOio

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Offline bozon

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Re: Bristol Beaufighter
« Reply #880 on: May 26, 2012, 09:00:00 AM »
inebriation.
lol, you made me look this word up.

I agree. What was the engineer that designed that smoking? I want some of that stuff!
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Offline bozon

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Re: Bristol Beaufighter
« Reply #881 on: May 26, 2012, 09:12:13 AM »
Beau's are so awesome that they even served in the IAF.
(from here: http://webspace.webring.com/people/qs/skythe/bomber1.htm)
Quote
In 1948 IAF agents in Britain purchased 6 Beaufighters from a company which had bought these from RAF stocks. The aircraft had not been taken care of for some time and were devoid of their essential avionics, navigation gear and guns, and an extensive overall was required. By the time the Beaufighters were ready to leave Britain for Israel, the British government had become aware of Israeli attempts to acquire weapons locally. As an arms embargo had been imposed on the opposing sides in the Israeli War of Independence, the Beaufighters were to be smuggled out of Britain. Under the pretext of participating in the shooting of a WWII film, 4 Beaufighters (one had crashed while another had been canibalized for spares) took off in front of the director, the cameras and the filming "crew" - and never returned. By the time the British authorities had come to, the aircraft were somewhere over the Mediterranean, on their way to Israel. From Britain the Beaufighters flew to Corsica and on to an airfield the Yugoslav government had allowed the IAF to operate from. On August 1st 1948 the aircraft arrived at Ramat David air base where they joined the 103rd bomber and transport squadron. The aircraft formed the squadron's 'B' flight, lead by Leonard Fitchett, a Canadian volunteer.

One IAF Beau got a maneuver kill on a Hawker Fury. One may wonder how many perk point that got him... I remember reading this story in a book long ago:

Quote
On the morning of October 19th, D.171 was sent to assist the Israeli Navy in battles against Egyptian naval vessels when it encountered an Egyptian Hawker Fury flown by Abd Al-Hamid Abu Zayd, commander of Egypt's 2nd squadron. Aware that the Beaufighter stood little chance in a dogfight, the pilot, Len Fitchett, jettisoned his bombload and put his bomber into a dive low over the water. Followed by the Egyptian, Fitchett abruptly pulled up, just in time to see the Fury crash into the sea.

« Last Edit: May 26, 2012, 09:13:49 AM by bozon »
Mosquito VI - twice the spitfire, four times the ENY.

Click!>> "So, you want to fly the wooden wonder" - <<click!
the almost incomplete and not entirely inaccurate guide to the AH Mosquito.
https://www.youtube.com/watch?v=RGOWswdzGQs

Offline nrshida

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Re: Bristol Beaufighter
« Reply #882 on: May 26, 2012, 11:25:11 AM »
lol, you made me look this word up.

I agree. What was the engineer that designed that smoking? I want some of that stuff!


The team of engineers that designed this series of engines were working principally under the direction of an engineering genius called Harry Ricardo, who in 1927(!) wrote a paper forecasting the limitations of the poppet valve and implying that the sleeve valve was the way forward.

He was instrumental in the advancement of the internal combustion engine and solved several significant problems. Out of interest, one of these involved work on the problem of detonation, his solutions where directly 'employed' by the Germans with their version of a methanol injection system (WEP in AH). He and Bristol, after expending millions of pounds making the sleeve valve viable were ordered to help Rolls Royce and more pressingly Napier who could not solve their problems with the Sabre engine (Typhoon / Tempest motor) which was needed for the war effort.



I do not know the expected lifespan of the valve drive gears Bustr, if that's what you are asking, but I can tell you that the overhaul interval for the Bristol sleeve valve series of engines was three times longer than that of its peers. Interestingly its peak fuel efficiency was also (approximately) at maximum power  :rock

The beauty of this design is twofold: there is far less power needed to actually operate the engine, and most importantly that the intake and exhaust ports are completely unobstructed when open, greatly increasing its volumetric efficiency.

The final iteration of this engine powered the Hawker Sea Fury. I trust you all know that aircraft.


I will upload some more material on the engine later if you are interested, some of it is hard to find but I needed it for a project.








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Offline bozon

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Re: Bristol Beaufighter
« Reply #883 on: May 26, 2012, 01:35:32 PM »
Thanks for the info. This engine discussion is more interesting than I would have expected  :aok
Mosquito VI - twice the spitfire, four times the ENY.

Click!>> "So, you want to fly the wooden wonder" - <<click!
the almost incomplete and not entirely inaccurate guide to the AH Mosquito.
https://www.youtube.com/watch?v=RGOWswdzGQs

Offline Karnak

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Re: Bristol Beaufighter
« Reply #884 on: May 26, 2012, 02:33:50 PM »
I had a coworker at my last job that was a bit fan of Bristol engines.  He loaned me a book to read on the development of WWII Bristol, Rolls-Royce and Napier-Sabre engines.  It was an interesting read.

One of the conclusions that I have reached over the last 10 years is that the biggest limiting factor for a nation in the 1930s or 1940s to self sufficiently built modern aircraft was whether or not they could build engines. Most smaller nations such as Australia, Denmark and Finland designed and built aircraft, but they always use engines designed and built elsewhere.  Only the United States, United Kingdom, France, Soviet Union, Germany, Italy and Japan seemed to have any significant ability to designed and manufacture their own engines.
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