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  1. #1
    Peter S is offline Titanium
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    A while ago Franco alerted me to this project, I have just found their website.

    I think the plan is to fly an original BE2e aircraft. The original engine was not usable, so it was decided to manufacture a new engine, in fact I think more than one was made.

    It is an RAF.1A, an air-cooled V8, originally from around 1912-13 I think, and based on an earlier Renault engine which appeared in 1909-10. Note the F-head with exhaust valve on top (a bit unusual). I think the capacity is 537 cu inch (8.8 litre) and rated at 90 hp at 1600 rpm.

    Normally these engines are described as having the propellor driven off the cam shaft, however I guess a less alarming description would be to say the camshaft is driven by the propellor reduction gearing! This is an early sucessful example of reduction gearing as most engines of the era (including this one) didn't run fast enough to require reduction. Also, author Herschel Smith points out that 2:1 reduction is not ideal, as the same teeth get the same loading on every revolution, this loading being a pulse - the uneven delivery of torque as each cylinder fires. However at 90 hp it worked, and as long as the mixture was kept very rich, the engine didn't overheat, and so it was known as a reliable if primitive engine.

    There are other pages on this website, but this one shows some of the machining:

    http://www.cams.net.nz/RAF-A1-Engine-Manufacture.htm

  2. #2
    Mike Powell's Avatar
    Mike Powell is offline Stainless
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    Peter S

    Thanks for sharing. It is absolutely amazing what can be accomplished with modern CNC equipment. I know the job would have been possible with all manual stuff but that CNC mill makes short work of tedious jobs like machining con rods and cylinder jug counter bores.

    Very cool!

    Mike

  3. #3
    Waumbek is offline Hot Rolled
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    This struck me as an absolutely spectacular effort that's really a kind of art form.

    It's great to look at the whole project from start to finish and save the video of the engine running for last. Great color graphics. I started looking at this point If you then click on the rebuild photo, you get to see the original engine they started with and get an overview of the project including some nice software shots.

    Many, many thanks. [img]smile.gif[/img]

  4. #4
    j.carlson is offline Hot Rolled
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    Great bit of work - congratulations to all involved for their success !

    However, the one fellow in the video is a slow learner when it comes to hot exhaust pipes ! Man that hurts !!

    Jim C.

  5. #5
    bryan_machine is offline Titanium
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    This is stunning work and really great to see a post of it. (Isn't the web great! You learn about all sorts of things you'd never see otherwise.)

    90hp on 8.8liters? Do you all realize how incredibly low power that was compared to even mildly tuned modern engines? This engine really is from very very early in the IC age...

  6. #6
    franco is offline Hot Rolled
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    Peter,

    Thanks for the website. There is a lot more information there than in the original article I saw. It really is a major undertaking.

    By the way, did you notice that Herschel Smith's photo of an RAF 1A on page 168 is in fact an 80 HP Renault? The aircraft is an early BE series, and these were fitted with the Renault engines. There is another photo of the Renault engine on page 23. They are quite distinctive, and externally noticeably different from the RAF engines. The X shaped brackets for the cylinder hold down bolts are a giveaway. The extra 10 HP from the RAF engine in the later BE series aircraft was probably very welcome.

    Regards,

    franco.

  7. #7
    Mike Powell's Avatar
    Mike Powell is offline Stainless
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    Well my '76 Goldwing has a 1000cc (1 liter) engine and it kicks out about 80-85 HP at about 7000 RPM. I dont know, can that airplane motor even run that fast?. I could put that monstor in my bike and it would look real cool but performance would likely fall off .

    Somebody stick a turbo on that thing!

    Mike

  8. #8
    Mike Wiggins is offline Aluminum
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    "90hp on 8.8liters? Do you all realize how incredibly low power that was compared to even mildly tuned modern engines? This engine really is from very very early in the IC age..."

    Not really true! 90 HP at 1600 RPMs is about 287 ftlbs of torque that is equal to about 300 hp at 5000 rpms. Then if you take the gear reduction which is driven off the cam drive at 2to1 you double the torque at the prop.

    "Well my '76 Goldwing has a 1000cc (1 liter) engine and it kicks out about 80-85 HP at about 7000 RPM. I dont know, can that airplane motor even run that fast?. I could put that monstor in my bike and it would look real cool but performance would likely fall off ."

    I don't belive that the Gold Wing motor could spin that prop at 7000 RPM,

  9. #9
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    Tip speed on prop has to stay below speed of sound. It is really very simple - big props turn slow, and even if they knew how to build such things in 1912, no one would want to hear 7000 rpm in a prop airplane with a recip engine [img]smile.gif[/img]

    I think far more interesting was that the very large engines did not weigh much.

    In later years, Wright Aeronautical built radials that weighed only a little more than 1 pound per HP.

    John

  10. #10
    franco is offline Hot Rolled
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    Mike P,

    Some interesting comments on the subject by Air Commodore Allen Wheeler, who was responsible for overseeing the design, production, testing and operation of the aircraft used in the film "Those Magnificent Men in their Flying Machines". One of the aircraft used in the film was a replica of a Bristol Boxkite. The original production aircraft was fitted with a 50 HP engine. He says:

    "On the other hand we were obliged to accept anachronisms so far as the engine installations went. In the case of the Boxkite it was initially decided to use a Rolls Royce Continental A.65 flat four engine rated at 65 HP. In discussion it was generally reckoned, even by the 'experts', that we would probably need a throttle stop to prevent the pilot from accidently using his excessive power and thus driving the Boxkite beyond its VNE (Velocity, Never Exceed). This proved to be the main and most astonishing miscalculation we made. When we came to test all the aeroplanes fitted with modern engines we discovered that with these higher powered modern engines we were not getting the same thrust apparently given by the lower powered rotary engines of 1910. Horses were clearly 'not what they used to be'. Both in the Boxkite and the Eardley Billing we eventually had to change to a Rolls Royce C.90 Continental engine developing 90 HP to get the thrust which seemed to have been adequately provided by the 50 HP Gnome rotary of 1910. Even with the C.90 engine we were faced with overheating troubles at one end of the heat range and carburetter icing troubles at the other end.......The explanation to all this must lie in the fact that the modern light aircraft engine gives its thrust at very high engine speed through a small diameter propeller which was not so efficient as the old Gnome propeller running at about half the speed."

    franco

  11. #11
    JST's Avatar
    JST
    JST is offline Diamond
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    Wot's all this about R-R "Continental" A65 and C90?

    Looks like a license agreement was done way back then "back in the day"?

  12. #12
    Asquith is offline Diamond
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    J,

    R-R made Continental engines under licence, from 1961 to 1982, although I think they made quite a few changes. The engines were built by the car division in Crewe, not by the aero engine division.

  13. #13
    Asquith is offline Diamond
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    By coincidence, I’ve just been reading an article in a 1917 copy of the magazine ‘The Engineer’ about the problems arising with alloy steel crankshafts for aero engines, written by two officers in the RAF (RAF then being the Royal Aircraft Factory). Entitled ‘The Use and Abuse of Steel’, it discusses the problems that arose following the unprecedented demand for alloy steel components. Many firms at the start of WW1 had neither the heat treatment facilities nor sufficient knowledge of metallurgical matters to produce satisfactory products. It couldn’t have helped that experienced men had gone off to fight, and vast numbers of inexperienced workers had become involved in manufacturing.

    Often, designers didn’t appreciate the metallurgical difficulties arising in making components from alloy steels. One of the roles of the RAF was to knock heads together, sort out problems, and spread intelligence.

    The RAF V8 isn’t mentioned as such, but I was interested to note that for a V12 engine they had at one point resorted to machining crankshafts from solid billets, as in the replica V8 engine.

    The V12 engine had cranks set at 120 degrees, and used ball/roller bearings. In the rough-machined state, the length of the journal between the crank webs was very short (7/16”). Far too short to contemplate twisting through 120 degrees, but that’s what they did.

    They had to heat to a very high temperature to do this, and no amount of subsequent heat treatment could restore the material condition. Various expedients were tried to avoid the problems caused by having to apply so much twist, including machining from solid, or forging to a trefoil shape before machining.

    The original method had been to forge a flat slab, and gashing between the webs, rough machining the journals, and heat treating, before twisting to set the cranks at approx 120 degree pitch, before heat treating again. To economise on material, the slab was just wide enough to have all the webs on one side and the journals on the other side before twisting. A simple improvement came from using a wider billet, positioning the journals in the middle, and having webs on each side. These then only needed to be twisted through 60 degrees, rather than 120. Even then, this wasn’t entirely satisfactory, and the authors were making the point that the design was not compatible with satisfactory manufacture.

    The article only hints at the vast amount of work that must have been done in WW1 both in terms of rapid development and in investment for mass production of weapons, munitions, engines, etc. Much like WW2 in that respect, but not in others. One difference was obviously in the reason for being at war. Another difference was that, from reading WW1 copies of ‘The Engineer’, life appeared to carry on as normal in many respects. Plenty of trade still going on. Letters debating the pros and cons of the metric system. One thing that did surprise me was the extent of technical disclosure in the magazine, information that you’d think would be useful to the enemy.

  14. #14
    franco is offline Hot Rolled
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    Asquith,

    Re the RAF V12 engine: like many of the WW1 air cooled stationary aircraft engines, cooling was marginal, and the engines were run very rich so that the cooling effect of the evaporation of the surplus fuel assisted in the cooling of the engine. V.M.Yeates, a WW1 Camel pilot mentioned in his book that he saw some RE8s ( RAF V12 engine) in the distance "puffing black smoke from the chimneys above the top wing as they went about their business”.

    Allen Wheeler mentioned that they finally cured the overheating problems with the Boxkite's Continental C.90 engine to the extent that they were able to make several cross country flights (at about 30 mph!) using the same approach.

    “Derek Piggott and Max Fripp borrowed some jet reamers from a garage in Dover and reamed out the main jet, thus giving the engine considerably more fuel than it needed but forcing it to evaporate it as it went through. The result was that the engine temperatures immediately dropped to within allowable limits and thereafter had no further trouble with the Boxkite engine.”

    franco

  15. #15
    bryan_machine is offline Titanium
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    "Not really true! 90 HP at 1600 RPMs is about 287 ftlbs of torque that is equal to about 300 hp at 5000 rpms. Then if you take the gear reduction which is driven off the cam drive at 2to1 you double the torque at the prop."

    Sure, but 8.8liters is rather large. A modern engine would displace about 1/2 that, or less. (while burning modern fuels and using modern tranmissions or speed-reducers.)

  16. #16
    Peter S is offline Titanium
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    I recently received a CD version of "Aerosphere 1939 World's Aero Engines". Had a quick look for RAF, there is about 2 1/2 pages listing all their engines plus some photos. In total there are around 850 pages on aero engines!

    I can recommend this CD to anyone who wants a huge book listing all the aero engines built up until 1939 - you wouldn't believe how many there are. (I believe the later editions did not have this comprehensive information).

    It is produced by Weak Force, from whom I get my "Great Aircraft Engines" calendar each year (well no one else is going to buy it for me! [img]smile.gif[/img]

    http://www.weakforcepress.com/

    ps, while browsing Aerosphere, I saw quite a lot about LeBlond aero engines, yes the same company.

  17. #17
    Mike Wiggins is offline Aluminum
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    Sure, but 8.8liters is rather large. A modern engine would displace about 1/2 that, or less. (while burning modern fuels and using modern tranmissions or speed-reducers.)

    Bryan
    I wasn't saying that new more modern engines couldn't do the job, What I was getting at don't get caught up in the HP ratings of an motor, HP is a measure of work (Torque)/ Time( RPM)this motor can do the same amout of work in half the time. It will last longer due less RPM and It's Air cooled, As far as displacement goes you have to go to a 8.0 litre ford engine to get the same bottom end torque numbers,

  18. #18
    Peter S is offline Titanium
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    I just looked at my Airboard Technical Notes from 1917 (mine is a recent reprint by Camden Books, excellent little booklet) - the 90 H.P. R.A.F. 1.a. is one of the featured engines.

    A slightly disturbing discovery - this engine does not have an oil pressure pump as such - it has a light steel flywheel which also acts as an oil circulating pump. I wondered why they had a photo showing a test of the oil circulation.

    The book says "lubrication is by gravity and splash". The lower part of the flywheel picks up oil from the sump and throws it into upper galleries and chamber from which feeds are taken.

    The main bearings being ball and roller get oil via metered pipes, the big ends are plain, so need plenty of oil. They have their own supply pipes. The big end journals are hollow, the crank webs have collector rings which take oil from the supply pipes into the hollow journals, from there out to the bearings through drilled holes.

    The flwheel throws extra oil about, so the chamber is kept overflowing, thus there is always enough oil.....

    I think if marketing departments had existed in those days, they may have come up with a more pilot-reassuring description than "gravity and splash"?

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