Author Topic: A game designer's viewpoint on AHWiki's aircraft descriptions.  (Read 5982 times)

Offline Murdr

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #60 on: February 05, 2009, 08:49:43 PM »
Gaston,

Did you not read my post.  This is not "jet era formulas".  The diagrams I posted are from 1940 .
« Last Edit: February 05, 2009, 08:55:24 PM by Murdr »

Offline Bronk

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #61 on: February 05, 2009, 09:00:31 PM »



     To Karnak; +25 lbs Spit IX top speed is 1-3 MPH higher than lower power Mk IXs, IF that... Of course, speed was increased +15-20 MPH at lower altitudes. Still, is it not VERY significant that no MK IX ever went beyond about 405 MPH TAS,


Erm  http://www.spitfireperformance.com/spitfire-IX.html   415.5 mph @ 27,800ft.  merlin 70


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Offline BnZs

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #62 on: February 05, 2009, 09:07:58 PM »
     ... I hope all those pancaking 190s were not thinking; "hey, with all those gs, I should be ok!..." For sure it was MUCH better, and slower, than hitting nose first like a frozen-stick Zero...

Oh lord, where to begin?

First of all, if "pancaking" means what I think it does in this context, then the aircraft is in a stall. Certainly an aircraft hitting the hitting the ground more or less belly first with the relative wind more or less *perpendicular* to the chord-line of the wing, then that wing is above critical AoA....and then some. The ability to pull your aircraft into an accelerated stall at a given speed does *not* mean you have bad pitch authority, it means the opposite.

     Unlike the jet era, where a given amount Gs WILL match a given rate of turn (although maybe not always so at the very lower range of speeds; ie; the Cobra), in WWII, Gs are little more than a factor of confusion, because they don't tell you exactly what the prop-driven contraption is actually doing...

I could be wrong, but I was under the relationship between speed and Gs in a turn and the turn rate/radius (in the subsonic range anyway) is no more variable or subject to debate than any other law of physics.
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Offline Murdr

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #63 on: February 05, 2009, 09:36:53 PM »
he posted two turning radiuses, both at 400 MPH TAS;

P-51D (probably metal elevators?); 450 ft. (!!!!)

Pure fantasy.  That's 75 degrees per second, and almost 24 Gs.  I'm almost curious enough to calcuate how ridiculously above CL max that would be....*almost*.

Offline Karnak

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #64 on: February 05, 2009, 10:06:32 PM »
To Karnak; +25 lbs Spit IX top speed is 1-3 MPH higher than lower power Mk IXs, IF that... Of course, speed was increased +15-20 MPH at lower altitudes. Still, is it not VERY significant that no MK IX ever went beyond about 405 MPH TAS, when the same-engine P-51B, or the MK XIV with little more power, did 440?... Why confuse the issue with what speed the Mk IX gained at SOME altitudes? Putting it another way, excluding the Japanese Military Power vs WEP debacle, show me a SLOWER top speed for a light weight fighter with 2000 HP... (Light weight excluding the Hellcat/Corsair etc...)

You are looking at blower limitations, IIRC.  At low altitude, where it could actually get +25lbs boost, it was ~15-20mph faster than +18lb boost Mk IXs.
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Offline Gaston

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #65 on: February 06, 2009, 01:55:13 AM »
    Bronk, the Spitfire Mk IX you are quoting at 415 MPH did so at 27 500 ft., and it was a high altitude Merlin 70 engine at +18 lbs, and had nowhere near 2000 hp...

    This did not see massive service, and in any case has NOTHING to do with the 2000hp +25 lbs low-altitude engine I was talking about...

    I am talking about the mass-produced LF Mk IX at +25 lbs; the main mass of Mk IXs produced. A super climber, but still unusually slow for a lightweight 2000 hp aircraft... Your claim that this 415 MPH top speed is from a 2000 hp +25lbs engine is false, and is clouding things more than clarifying them... I'll concede that this site IS confusing...

    Murdr, How do you know how many Gs the P-51 takes in its HISTORICAL 450 ft. wide, 400 MPH TAS turn, when you don't even know the LENGTH of the curve, or how much slippage/rotation/deceleration the aircraft does? Show me your formula taking into account these factors, I'd be real curious to see it...

    I've just explained in the previous post how a 0ft. radius, 400 MPH 180 ° turn could have perfectly acceptable Gs. (If quite a long length!)

    If you guys really think a 450 ft. wide turn at 400 MPH is impossible, why don't you ask Skychimp where the data came from? I'm sure some of you guys know him better than I do... He posts regularly on Il-2 GD.

    If you can't believe the extensive flight tests of the 1990s, that show CONCLUSIVELY the best P-47/P-51 turn rate was near 400 MPH, why don't you look up that series of tests? Its conclusions were in numerous aviation-related sites/articles, and achieved with a fairly large number of pilots... I will try to find the link.

    On top of that, those tests are barely 18 years old; I'm pretty sure a good number of these pilots are still around to let some reality intrude here...

    Gaston.

   
   

   

   
     
« Last Edit: February 06, 2009, 01:58:23 AM by Gaston »

Offline Angus

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #66 on: February 06, 2009, 03:44:32 AM »
"Murdr, How do you know how many Gs the P-51 takes in its HISTORICAL 450 ft. wide, 400 MPH TAS turn, when you don't even know the LENGTH of the curve, or how much slippage/rotation/deceleration the aircraft does? Show me your formula taking into account these factors, I'd be real curious to see it...

If the diameter of the circle is 450 feet and the speed is 400 mph, it means a whole circle done in about 2.5 seconds. Don't see that one possible, I'm afraid....
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Offline Charge

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #67 on: February 06, 2009, 04:50:11 AM »
Just a simple question when you seemed earlier to be discussing "Energy" and form to get it, lose it and utilize it. Isn't it so that while in jet aircraft you can "use the weight" of the aircraft to gain engine efficiency by ramming air to turbine in prop planes you really do not gain almost anything in thrust by diving.

By that I mean that while in a tail chase it is beneficial in a jet to go for 0 Gs for some time to gain speed and thus more thrust so you might actually be able to close the gap to the plane you are pursuing where as in prop planes while accelerating you actually gain nothing by diving because the prop does not benefit from faster airflow but only the effect of drag becomes bigger. Of course you might be able to utilize the excess energy gained by diving in speed that will wear out after a while or try to zoom up to target to get a snap shot but all in all you end up in less energy than by simply flying behind your target and trying to catch it in level flight.

If that is true then it probably has an effect how efficient or inefficient certain "energy transfer" maneuvers are in prop planes and in jets?

***

"I hope all those pancaking 190s were not thinking; "hey, with all those gs, I should be ok!..." For sure it was MUCH better, and slower, than hitting nose first like a frozen-stick Zero.."

If a plane stalls through a turn it doesn't really create as much Gs as it would with flow attached as the Gs in maneuvers are created by the mass changing its direction. A 190 mushing to ground after a dive is unable to change the direction of its mass and thus unable to create much Gs. The theoretical max AoA of its wing profile is around 16 deg but going straight down it could be more so even while totally stalled the wing would certainly decelerate the plane but how much I cannot estimate. I've been in a similar situation even in AH with 190A8 (quite often actually) that while pulling up from a dive the wing stalls and the plane tries to mush into ground and if you do not ease the stick to reattach the flow it will certainly auger. I'm sure many novice 190 pilots fell for that during WW2 and I'm sure other planes did that too, but of course a plane with high wingloading is more prone to that kind of behaviour. The difference to 190s benefit would have been that at least it had a wing that could handle such accelerations without failing but might also be its shortcoming since the pilots learned that you could always trust the wing to be able to handle the load of any kind of maneuvers, but to keep the load on wing was another matter and in panic many forgot or simply did not know (which is my bet).

***

".50 cals were *quite* deadly in Korea at jet speeds."

Not really. There are even some estimates of how many sure kills they lost because of the ineffectiveness of .50s. The enemies went "down" all right, but damaged, not destroyed and due to distance to Chinese border they often got away to fly another day. The Migs were not very effective since, as seen during WW2, cannon armament requires a skilled shooter, where as with a shotgun you are bound to get more hits but with less effect. The deceleration of a light projectile is bigger than that of a heavy and in jet speeds that has bigger effect on effective range than in prop fighters. Of course that is relative also so that a bullet fired from a jet flies faster and further than that fired from a prop plane but in relation to target flying at same speeds the effective range is shorter. I don' think there's much doubt that with 4 20mms in Sabres the results would have been much better. That is due to old wisdom that while fighting over enemy territory you need to carry armament that will  d e s t r o y the enemy and not just cripple him, as if he is able to land you are fighting a losing war on attrition.

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« Last Edit: February 06, 2009, 04:52:37 AM by Charge »
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Offline Bronk

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #68 on: February 06, 2009, 05:18:31 AM »
    Bronk, the Spitfire Mk IX you are quoting at 415 MPH did so at 27 500 ft., and it was a high altitude Merlin 70 engine at +18 lbs, and had nowhere near 2000 hp...

    This did not see massive service, and in any case has NOTHING to do with the 2000hp +25 lbs low-altitude engine I was talking about...

    I am talking about the mass-produced LF Mk IX at +25 lbs; the main mass of Mk IXs produced. A super climber, but still unusually slow for a lightweight 2000 hp aircraft... Your claim that this 415 MPH top speed is from a 2000 hp +25lbs engine is false, and is clouding things more than clarifying them... I'll concede that this site IS confusing...


       Still, is it not VERY significant that no MK IX ever went beyond about 405 MPH TAS
]
Then please be more specific.  Which Mk IX are we talking about? Being the the Mk they tried hanging every engine/wing combination off of.. to do every job needed. I'm talking geared from low alt work to high alt photo recon.

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Offline Payed

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #69 on: February 06, 2009, 07:11:55 AM »
400mph and 450ft radius? Holly G-force, Batman!

http://en.wikipedia.org/wiki/Centripetal_force

Offline hitech

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #70 on: February 06, 2009, 09:45:38 AM »
Quote
  Murdr, How do you know how many Gs the P-51 takes in its HISTORICAL 450 ft. wide, 400 MPH TAS turn, when you don't even know the LENGTH of the curve, or how much slippage/rotation/deceleration the aircraft does? Show me your formula taking into account these factors, I'd be real curious to see it...

Thanks you have just made this a great day , because bursting out in laughter always lightens my mood.

Hmm I believe it was in 4th grade I learned Circumference (I.E. the distance around a circle for the physics impaired) =  2 Pi r = Pi d.

HiTech

Offline Murdr

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #71 on: February 06, 2009, 10:10:59 AM »
Well, looks like everyone beat me to it.  Newtons Second Law, and a little value called Pi that the Greeks discovered a couple thousand years ago.  Fluid dynamics without thrust vectoring, exclude or invalidate every rational you've come up with.  Since you've ignored my previous post containing lots of info, including period data, there's no need to waste my time explaining anything further, because you have no real interest in the reply.

But we don't need to look up someone who has flown a real P-51, because we have someone right here who just posted ahead of me.

Offline Rebel

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #72 on: February 06, 2009, 10:13:49 AM »
WOW. 

That's gotta be a 10G turn at least, doesn't it?  I'm no good with math. 
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Offline Karnak

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #73 on: February 06, 2009, 10:37:27 AM »
WOW. 

That's gotta be a 10G turn at least, doesn't it?  I'm no good with math. 
Closer to 25g turn I think.
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Offline BnZs

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Re: A game designer's viewpoint on AHWiki's aircraft descriptions.
« Reply #74 on: February 06, 2009, 10:52:39 AM »


"I hope all those pancaking 190s were not thinking; "hey, with all those gs, I should be ok!..." For sure it was MUCH better, and slower, than hitting nose first like a frozen-stick Zero.."

If a plane stalls through a turn it doesn't really create as much Gs as it would with flow attached as the Gs in maneuvers are created by the mass changing its direction. A 190 mushing to ground after a dive is unable to change the direction of its mass and thus unable to create much Gs. The theoretical max AoA of its wing profile is around 16 deg but going straight down it could be more so even while totally stalled the wing would certainly decelerate the plane but how much I cannot estimate. I've been in a similar situation even in AH with 190A8 (quite often actually) that while pulling up from a dive the wing stalls and the plane tries to mush into ground and if you do not ease the stick to reattach the flow it will certainly auger. I'm sure many novice 190 pilots fell for that during WW2 and I'm sure other planes did that too, but of course a plane with high wingloading is more prone to that kind of behaviour. The difference to 190s benefit would have been that at least it had a wing that could handle such accelerations without failing but might also be its shortcoming since the pilots learned that you could always trust the wing to be able to handle the load of any kind of maneuvers, but to keep the load on wing was another matter and in panic many forgot or simply did not know (which is my bet).


Like I said before, not having enough lift available to alter your course is not an elevator authority problem, the 190 can "mush" into the ground in certain situations like this because its wingloading is so darn high.

***

".50 cals were *quite* deadly in Korea at jet speeds."

Not really. There are even some estimates of how many sure kills they lost because of the ineffectiveness of .50s.

Yet still  .50s were bringing down jets fighting at high-subsonic speeds. Where does that leave the OP's contention that WWII armaments, many of which were greater than .50s, were too impotent to bring down enemy aircraft except by saddling up and pouring out the entire ammo load? The central problem was always the pilot's aiming abilities and experience.


"The bellybutton kissing in this thread is amazing.  So is the rudeness towards the O/P."   Just what I was thinking too...  :lol

It is ass-kissing or rude to question information that includes, among other things, literal physical impossibilities?
« Last Edit: February 06, 2009, 11:04:07 AM by BnZs »
"Crikey, sir. I'm looking forward to today. Up diddly up, down diddly down, whoops, poop, twiddly dee - decent scrap with the fiendish Red Baron - bit of a jolly old crash landing behind enemy lines - capture, torture, escape, and then back home in time for tea and medals."