Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Charge on February 23, 2010, 05:05:08 AM
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Looking at WWI aircraft pictures I noticed that the engine cylinders did not seem to rotate at all. These airplanes had rotary engines which meant that the whole cylinderblock rotated with the propeller.
There is a rather enlightening article about this type of engines and their engine management in Wiki: http://en.wikipedia.org/wiki/Rotary_engine
Imagine the torque and gyroscopic effects of the massive engine rotation force on such light airframes.
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I visited Brooklands aerdrome (UK) where, by chance, I met a restoration expert working on an old Sopwith. I can't remember if it was a Pup or a Camel. The 'point' of the plane was to put all the major weight centrally within the first 3 feet of the airframe and 7 feet including the pilot. This led to it being small and amazingly manouverable. It could roll a 3/4 turn in one direction in the same time it took to roll 1/4 turn the other way because of the engine torque.
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You can be sure that HTC is very familiar with rotary radial engines. I've been waiting 8 years for them to model WW1 aircraft again. :x
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I also believe that the WWI planes are going to be a blast to play with. From interest shown on the boards, that arena should be fairly well represented.
One thing I found interesting about some of the WWI rotaries was that there was no throttle control. Engine rpm's and power were controlled by the ability to drop ( shut off spark) cyiinders with magneto settings. Should be interesting
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These airplanes had rotary engines which meant that the whole cylinderblock rotated with the propeller.
Haven't read that wiki-article but yep, that's how it was. :) The basic reason was that the cylinders were machined rather than cast. The casting techniques simply weren't there to manufacture cylinders with cooling fins. So the cylinders were machined and the cooling was arranged by the fast airflow around the cylinders as the engine rotated.
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Very nice intro into the principals and operation of rotary engines:
http://www.youtube.com/watch?v=HXf3StrRHcc (http://www.youtube.com/watch?v=HXf3StrRHcc)
http://www.youtube.com/watch?v=Nk9Dl6RZxmQ (http://www.youtube.com/watch?v=Nk9Dl6RZxmQ)
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Torque and gyroscopic force: http://www.youtube.com/watch?v=Ch7Z4UurPSk&feature=related
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More to the point, will the torque / gyro stuff be modelled? Didn't the Camel pilots have to displace the stick at 90' to the direction in which they wanted to go?
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Torque and gyro are already modeled in AH.
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This video has some nice stuff too:
http://www.youtube.com/watch?v=j6PnKUEFX8g
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Torque and gyro are already modeled in AH.
Yes they are, I think it's largely just about using the right parameters to model the effects as accurately as possible...plus misc. tweaking. :)
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The Old Rhinebeck Camel has a 160 hp Gnome Rotary engine. When it's started the wing dips 6-8 inches IIRC. One of the pilots told me that it's not that hard to fly, you just have to know what to expect. I believe if it's modeled correctly people will think it's too easy, even if every newbie that tries it crashes the first time. :joystick:
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Am I right in thinking that the rotaries were either full throttle or full idle, nothing in between?
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You could adjust the "full on" with the fuel air mixture. The OP's wiki link explains it.
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Am I right in thinking that the rotaries were either full throttle or full idle, nothing in between?
There were also a method cutting the ignition for every other or every third cylinder in a changing firing order which lead into "50%" and "33%" settings between all out and idle. Check the first youtube-link I posted.
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Thanks.
I have it in my head somewhere that I saw a TV program where a physics prof demonstrated that to turn to the left, one needed to displace the stick backwards (i.e. not to the left).
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Fear the blip switch! :D Leave it on too long and you've got a glider with a couple
hundred pounds of ballast in the nose :rofl
Of course I do wonder about the in-lineengined birds like the Fokker D-VII or the
Albatross D-V, anyone know what kind of throttle system they used? The irony is,
I have seen an Albatross fly up at Old Rhinebeck and never thought of this question.
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"I have it in my head somewhere that I saw a TV program where a physics prof demonstrated that to turn to the left, one needed to displace the stick backwards (i.e. not to the left)."
I think that is oversimplification. After you initiate the turn the downwards or upwards momentum depends on how tight turn you initiate, but of course the aircraft likes to go faster downwards than upwards. I think it is just that you need to keep in mind when turning to right (depending how hard you turn) that you need to apply also elevator and some opposite rudder to keep the turn level and coordinated. Or if you are in a tight spot you could just yank a right turn and let the engine mass do its trick and also make the tendency more pronounced with elevator and rudder.
AFAIK as with FW190's "flick roll" the Camel could "flick turn" as well so tightly that it was almost impossible to follow. Why this was more pronounced in Camel that in other planes?
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Of course I do wonder about the in-lineengined birds like the Fokker D-VII or the
Albatross D-V, anyone know what kind of throttle system they used? The irony is,
I have seen an Albatross fly up at Old Rhinebeck and never thought of this question.
Unlike the rotaries, WWI-era inlines used pretty much conventional carburators so they had a normal, linear throttle control. The reason for the spartan throttle control in the rotaries was the lack of conventional carbs, ie. the mixture was fed through the stationary crankshaft into crankcase from where it was fed into the cylinders with a few different methods depending on the particular engine.
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More nice rotary engine stuff:
http://www.animatedengines.com/gnome.shtml (http://www.animatedengines.com/gnome.shtml)
http://www.enginehistory.org/Gnome%20Monosoupape.pdf (http://www.enginehistory.org/Gnome%20Monosoupape.pdf)
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Nice link thanks.
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Looking at WWI aircraft pictures I noticed that the engine cylinders did not seem to rotate at all. These airplanes had rotary engines which meant that the whole cylinderblock rotated with the propeller.
There is a rather enlightening article about this type of engines and their engine management in Wiki: http://en.wikipedia.org/wiki/Rotary_engine
Imagine the torque and gyroscopic effects of the massive engine rotation force on such light airframes.
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How would you see movement in an ah picture? They are not like real life where a blur occurs when the photo is taken.
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How would you see movement in an ah picture? They are not like real life where a blur occurs when the photo is taken.
Ahh yeh, missed that bit of Charge's original post.
Charge, yeh, the rotaries are animated. I noticed that from an .ahf taken of the Super Fokkers during the Evil Con Mission. :)
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All this talk is making me more eager than ever to jump in one. Any ideas on a release date? :headscratch:
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There were also a method cutting the ignition for every other or every third cylinder in a changing firing order which lead into "50%" and "33%" settings between all out and idle. Check the first youtube-link I posted.
If you kept cutting the ignition of every other or third cylinder you'ld end up with fouled up spark plugs in short order on those cylinders. The Gnome Monosaupapes actually had an elaborate gear works on the magneto control that rotated the "off" cylinder plugs alternately with the ones that were receiving ignition sparks, so to keep all the plugs relatively clean and hot. The other thing about the early Gnomes were that the intake valves were in the head of the piston, were complex and needed servicing every 50 hours of operation. Since they were operated by atmospheric pressure they limited the altitude ceiling and the power output.
The Clergets, Lehones,and Bentleys had individual air and fuel controls, some were in a semi automatic linking arrangement, but most could be individually adjusted. You didn't reduce the throttle much below 50% so as to keep the flow of Castor oil well distributed in the engine. The oil was pumped crudely into the intake runner and since Castor oil doesn't mix well with gasoline, it was drawn along by the fuel-air mixture.
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Good info and welcome to Aces High.
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If you kept cutting the ignition of every other or third cylinder you'ld end up with fouled up spark plugs in short order on those cylinders.
I guess I worded it badly by saying "changing firing order" but...
The Gnome Monosaupapes actually had an elaborate gear works on the magneto control that rotated the "off" cylinder plugs alternately with the ones that were receiving ignition sparks
...this is what I meant.
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For wickedly, fiendishly complex, it's hard to beat the Siemens-Halske Sh.III geared rotary:
http://en.wikipedia.org/wiki/Siemens-Halske_Sh.III
Yeah, that's just what you want in an aircraft engine, complexity. :rolleyes:
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For wickedly, fiendishly complex, it's hard to beat the Siemens-Halske Sh.III geared rotary:
http://en.wikipedia.org/wiki/Siemens-Halske_Sh.III
Yeah, that's just what you want in an aircraft engine, complexity. :rolleyes:
The Siemens rotary suffered more from the ersatz Castor oil the Germans were forced to use later in the war. The engine design was fine but it suffered from heat and wear that would have been lessened if it could have been run on real Castor. Marvelous idea and it ran relatively fast for a rotary.
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"How would you see movement in an ah picture? They are not like real life where a blur occurs when the photo is taken."
Of course, sry 'bout that. :aok
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How would you see movement in an ah picture? They are not like real life where a blur occurs when the photo is taken.
Can't you do it in the same way you do the propellers? It does look a bit odd.
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Well, I think that the propeller is just a disk with blurred propeller image which rotates slowly but they can rotate the cylinders just as the objects they are so that in game the engine looks blurred as it should.
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