Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Raptor on December 03, 2009, 12:33:16 AM
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In the New Version:
The static and low speed thrust (<100mph) of the P-38L was lower than it was supposed to be. It's now the same as the P-38J.
Fixed some prop efficiency errors on numerous planes that gave too much thrust below best climb speed at high altitudes.
What does this mean for the engineering illiterate?
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Not much flying under 100mph... maybe it just means the 38L's take off run was longer than it should have been.
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Not much flying under 100mph... maybe it just means the 38L's take off run was longer than it should have been.
Um... how would that coding error happen? Isn't there a formula they're using? lol.
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I think there were a few planes that could literally hang on the prop when they shouldnt (vis-a-vis prop efficiency).
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I think there were a few planes that could literally hang on the prop when they shouldnt (vis-a-vis prop efficiency).
Fortunately for us Lightning drivers, the P-38 isn't one of those planes that shouldn't be able to hang on its prop.
ack-ack
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Fortunately for us Lightning drivers, the P-38 isn't one of those planes that shouldn't be able to hang on its prop.
ack-ack
ummm define hang ...
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ummm define hang ...
When held perfectly vertical, it will virtually stop in midair and stay there much longer than other fighters. It also has the ability to take an equal amount of starting energy and, when pulled straight up, climb higher than most (if not all) other fighters.
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D'oh forgot about prop hanging. :)
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When held perfectly vertical, it will virtually stop in midair and stay there much longer than other fighters. It also has the ability to take an equal amount of starting energy and, when pulled straight up, climb higher than most (if not all) other fighters.
you mean in the game?
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you mean in the game?
No were talking about the 38's preformance on Mars.
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:rofl
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No were talking about the 38's preformance on Mars.
I gotta admit I've been sitting here trying to think of something smartass to say, but this was good!
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No were talking about the 38's preformance on Mars.
Fortunately for us Lightning drivers, the P-38 isn't one of those planes that shouldn't be able to hang on its prop.
ack-ack
well you guys are confusing
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In the New Version:
What does this mean for the engineering illiterate?
Basically, propeller efficiency peaks out around 80% for most aircraft, at some point of its performance envelope--most of the time this is at high-speed cruise or close to maximum speed for the aircraft (more or less). This is because no propeller is 100% efficient--i.e. it can't turn all of the engine power into thrust. The propeller chosen for a certain powerplant is always selected based on a desired performance range. Inside that range, the prop will stay in the upper parts of its efficiency curve--say between 60-80% efficiency.
At slow speeds, or with no speed on the plane though, the prop is not very efficient. It appears that HTC made some corrections to the way they model this "static" and low-speed thrust by lowering the propeller efficiency curves for some aircraft.
I could throw the thrust and prop efficiency equations up if desired...
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It means people will have an excuse to explain how my the 38L owns....
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It means people will have an excuse to explain how my the 38L owns....
It means all the 38 SAPP peoples will be flying Zeros from now on. :lol
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No were talking about the 38's preformance on Mars.
:rofl
ack-ack
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I think there were a few planes that could literally hang on the prop when they shouldnt (vis-a-vis prop efficiency).
Fortunately for us Lightning drivers, the P-38 isn't one of those planes that shouldn't be able to hang on its prop.
ack-ack
you mean in the game?
No were talking about the 38's preformance on Mars.
:rofl
ack-ack
are you trying to say you were not referring to the real world in the exchange above?
because the word "shouldn't" really is out of place if you were only discussing the game, or Mars.
if you are now trying to imply that real world capabilities were not on your mind,
then i am not sure which is more sad,
your feeble attempt to wiggle out from under your original statement with a gif,
or the lack of understanding that allowed you to post it in the first place.
When held perfectly vertical, it will virtually stop in midair and stay there much longer than other fighters. It also has the ability to take an equal amount of starting energy and, when pulled straight up, climb higher than most (if not all) other fighters.
p38 ??? :huh :lol :rofl
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are you trying to say you were not referring to the real world in the exchange above?
because the word "shouldn't" really is out of place if you were only discussing the game, or Mars.
if you are now trying to imply that real world capabilities were not on your mind,
then i am not sure which is more sad,
your feeble attempt to wiggle out from under your original statement with a gif,
or the lack of understanding that allowed you to post it in the first place.
p38 ??? :huh :lol :rofl
I was responding to Stoke's post because I found it to be rather funny, especially since his sarcastic post seems to have gone completely above your head.
Yes, the P-38, in real life, had excellent vertical performance and due to lack of torque from its counter rotating props, had the ability to hang 'on its props' while in the vertical maneuver. Coupled with having two engines, good E retention, low stall speed and gentle stall characteristics and very easy stall recovery, all gave the Lightning excellent vertical performance.
So please, regale me with your 'experten' knowledge and tell me how the P-38 was not good in the vertical in real life and the P-38's vertical performance in the game is due to incorrect flight model. I'm sure you'll have just about as much success in proving yourself correct as you've had in your previous threads.
ack-ack
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you mean in the game?
(facepalm)
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This thread is going well.
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This thread is going well.
It's not thorsim's fault...he's just a luftwhiner and asking them to change would be like asking a leopard to change his spots.
ack-ack
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you sure about all that ...
I was responding to Stoke's post because I found it to be rather funny, especially since his sarcastic post seems to have gone completely above your head.
Yes, the P-38, in real life, had excellent vertical performance and due to lack of torque from its counter rotating props, had the ability to hang 'on its props' while in the vertical maneuver. Coupled with having two engines, good E retention, low stall speed and gentle stall characteristics and very easy stall recovery, all gave the Lightning excellent vertical performance.
So please, regale me with your 'experten' knowledge and tell me how the P-38 was not good in the vertical in real life and the P-38's vertical performance in the game is due to incorrect flight model. I'm sure you'll have just about as much success in proving yourself correct as you've had in your previous threads.
ack-ack
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you sure about all that ...
He still doesn't get it...
(http://i935.photobucket.com/albums/ad193/bundy526/PatStewartdouble-facepalm.jpg)
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you sure about all that ...
That in real life the P-38 had excellent vertical performance? Yes, I am sure.
ack-ack
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He still doesn't get it...
(http://i935.photobucket.com/albums/ad193/bundy526/PatStewartdouble-facepalm.jpg)
(http://cdn0.knowyourmeme.com/i/6512/original/DoubleFacePalm.jpg)
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Interesting how everyone else posts statistics, figures, and research and he replies with single sentences as if he's threatening to open the floodgates in hopes that everyone will get scared off and he can claim victory. :lol
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I think what he actually does is 'cherry pick' from posts and tries to tie them together in a way inconsistent with the original posters intent.
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That in real life the P-38 had excellent vertical performance? Yes, I am sure.
ack-ack
no are you sure about this ...
had the ability to hang 'on its props' while in the vertical maneuver
for all the reasons you stated below ...
Yes, the P-38, in real life, had excellent vertical performance and due to lack of torque from its counter rotating props, had the ability to hang 'on its props' while in the vertical maneuver. Coupled with having two engines, good E retention, low stall speed and gentle stall characteristics and very easy stall recovery, all gave the Lightning excellent vertical performance.
because i am not sure those are the attributes that would allow a plane to do this ...
When held perfectly vertical, it will virtually stop in midair and stay there much longer than other fighters. It also has the ability to take an equal amount of starting energy and, when pulled straight up, climb higher than most (if not all) other fighters.
or something like that ...
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Two engines. High efficiency airframe. High inertia. Efficient propellers. General engineering genius.
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Two engines. High efficiency airframe. High inertia. Efficient propellers. General engineering genius.
yea and prop hanging as described in this thread i as far as i know is reserved to "real" planes like this (which is nothing like a p-38) or RC aircraft ...
http://www.youtube.com/watch?v=fb91oekRqYU&feature=fvw
IMO it is very much a stretch to attribute "prop hanging" abilities as described to any of the hight performance fighters represented in this game and yes that would include the luftwaffe planes ACK ACK ...
if HTC has reduced that sort of ability for the planes ALL THE PLANES in the game then i say WTFG HTC ...
oh and btw he seems to manage his torque just fine without the counter rotating props ...
the maneuver looks like all BHP/weight and the ability of the prop to translate that BHP to effective thrust in this flight mode. not at all attributes that were significantly superior in the p-38 relative to the other planes it fought with or against and compared to the extra 540/su31 and other planes that can prop hang is decidedly inferior ...
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They're talking about an aircraft's ability to hang for a few moments at the end of a zoom climb, not to pitch up and hang on the prop for several seconds/minutes.
oh and btw he seems to manage his torque just fine without the counter rotating props ...
I'm not sure what type of engine is in that plane but I would imagine it's not 2,000+ horsepower.
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They're talking about an aircraft's ability to hang for a few moments at the end of a zoom climb, not to pitch up and hang on the prop for several seconds/minutes.
Exactly.
Also, I didn't mention anything about counter-rotating propellers. You're just pulling from old conversations where you expect people to say certain things, so you can throw the same things back, I suppose.
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a few moments is IMO a stretch, power/weight suggests that you would loose momentum and then immediately drop tail first to deal with that "stall" a situation where a neutral roll tendency might be problem not an advantage.
but hanging sorry not buying it,
ozz, ACK ACK said the thing about the counter rotating props i was replying to him,
about him thinking that what you described the first time was able to be done in the p38 in the real world ...
i did not mean that you thought this was possible i thought you were describing a game thing that HTC noted in their update. ACK ACK seems to think such things are within the capabilities of the p38.
i disagreed ...
the video shows what i understood you to describe in your earlier post and is i suspect well beyond the capabilities of any of the real world fighters represented in the game.
it is hard to discuss things when i ask what someone means then disagree with them only for them to say oh that isn't what i meant ...
They're talking about an aircraft's ability to hang for a few moments at the end of a zoom climb, not to pitch up and hang on the prop for several seconds/minutes.I'm not sure what type of engine is in that plane but I would imagine it's not 2,000+ horsepower.
Exactly.
Also, I didn't mention anything about counter-rotating propellers. You're just pulling from old conversations where you expect people to say certain things, so you can throw the same things back, I suppose.
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This was the first thing I thought of when I saw 'hanging on the props"
I know it's a warbird pilot, but he's referencing his father's combat experience. I'll find it from a combat 38 driver too, but this is the one I thought of first.
Qouting from the Jeff Ethell article in Flight Magazine, August 1997
"At 100 mph I could hang the P38 on it's props, feet on the floor and gently move the rudder slide side to side."
Also from the same article, talking about his father Erv Ethell, who flew combat in 38Fs in the MTO with the 14th FG and who was also a P38 instructor afterwards.
"Without much thought. I was entering his (Erv Ethell's) preferred combat maneuver; power up, I pictured a 109 on my tail and began and increasingly steep right handed climbing turn. In turning and twisting with 109s and 190s, Dad never got a bullet hole in his P38F "Tangerine". As the speed dropped below 150mph,I flipped the flap handle to the maneuver stop (which can be used up to 250mph) amd tightened the turn. At this point, the 109 pilot, at full power with the right rudder all the way down, would have snap rolled into a vicious stall if he had chosen to follow. I pulled the power back on the inside (right engine), pushed the power up on the outside (left) engine, shoved right rudder pedal, and the Lightning smoothly swapped ends. Not only did it turn on a dime, but it rotated around it's central axis as if spinning on a pole running through the top of the canopy and out the bottom of the cockpit. The maneuver was absolutely comfortable with no heavy G loading. I threw the flap lever back to full up, evened the throttles and heading down going through 300mph in less time then it tals to tell it. The 109 would have been a sitting duck."
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That's a great article and the video that he made of that flight is also great and a must see for anyone wanting to learn the P-38. IIRC, part of the video he made is a remake of the USAAF P-38 flight training film. It's been a few years since I've watched the video, haven't had a VCR in like 10 years.
ack-ack
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a few moments is IMO a stretch, power/weight suggests that you would loose momentum and then immediately drop tail first to deal with that "stall" a situation where a neutral roll tendency might be problem not an advantage.
The counter rotating props are not problem and do give the P-38 an edge in vertical maneuvers since there isn't any unnecessary energy loss due to the pilot countering the effects of torque. One of the benefits of having a plane without engine torque I guess.
but hanging sorry not buying it,
ozz, ACK ACK said the thing about the counter rotating props i was replying to him,
about him thinking that what you described the first time was able to be done in the p38 in the real world ...
i did not mean that you thought this was possible i thought you were describing a game thing that HTC noted in their update. ACK ACK seems to think such things are within the capabilities of the p38.
i disagreed ...
the video shows what i understood you to describe in your earlier post and is i suspect well beyond the capabilities of any of the real world fighters represented in the game.
it is hard to discuss things when i ask what someone means then disagree with them only for them to say oh that isn't what i meant ...
I think you may be taking "hanging on its props" to its literal meaning and thinking of those RC maneuvers were an RC plane can fly around like a helicopter while it hangs on its props. Of course, I do not mean that at all, OZZ pretty much gave a pretty good explanation of what is meant by 'hanging on its props'. Dan/Guppy35 also posted another good description from Jeff Ethell (who had many hours in a P-38 prior to his passing) in addition to his father's comments.
Counter-rotating props, two powerful engines, zero torque, good energy retention, low stall speed and very gentle stall characteristics and stall recovery allowed the P-38 to hang on its props and excel in the vertical. Sure, there are other things that contribute to the P-38s excellent vertical performance, those I listed are just the general attributes that made it possible in real life.
Care to provide data that shows contrary?
ack-ack
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When one says the P38 can hang on its props one IS NOT saying the P38 is a V22 tilt rotor, but rather that it can hang at the apex of a zoom climb for a short moment and still have this very stable behavior that makes it a dream to get pointed back down again, while the roped prey is 300 yards underneath flailing about like a fish out of water falling at 100 mph practically sitting there waiting for the P38 to zap it.
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"Without much thought. I was entering his (Erv Ethell's) preferred combat maneuver; power up, I pictured a 109 on my tail and began and increasingly steep right handed climbing turn. In turning and twisting with 109s and 190s, Dad never got a bullet hole in his P38F "Tangerine". As the speed dropped below 150mph,I flipped the flap handle to the maneuver stop (which can be used up to 250mph) amd tightened the turn. At this point, the 109 pilot, at full power with the right rudder all the way down, would have snap rolled into a vicious stall if he had chosen to follow. I pulled the power back on the inside (right engine), pushed the power up on the outside (left) engine, shoved right rudder pedal, and the Lightning smoothly swapped ends. Not only did it turn on a dime, but it rotated around it's central axis as if spinning on a pole running through the top of the canopy and out the bottom of the cockpit. The maneuver was absolutely comfortable with no heavy G loading. I threw the flap lever back to full up, evened the throttles and heading down going through 300mph in less time then it tals to tell it. The 109 would have been a sitting duck."
I do this all the time in game. Very cool to hear it being done during the war.
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that is all well and good, but ...
the posted account is not what was described as prop hanging earlier in this thread ...
climbing away from an e-enemy in a spiral against his prop torque was not a "special" 38 tactic the spits and 109s did it vs. each other throughout the war.
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that is all well and good, but ...
the posted account is not what was described as prop hanging earlier in this thread ...
climbing away from an e-enemy in a spiral against his prop torque was not a "special" 38 tactic the spits and 109s did it vs. each other throughout the war.
You are missing the point. What is initially described is an abilty to hang on the props and not have it pull to one side due to torque. As mentioned in what I quoted, the single engine bird would have stall spun from the torque. In that regards the lack of torque was special to the 38 in combat. Can't think of a single engine fighter where you could be hanging on the prop at 100mph moving rudder from side to side.
The second example was just one of how that twin engine, lack of torque could be used to an advantage in combat.
Frankly this just isn't that complicated.
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that is all well and good, but ...
the posted account is not what was described as prop hanging earlier in this thread ...
climbing away from an e-enemy in a spiral against his prop torque was not a "special" 38 tactic the spits and 109s did it vs. each other throughout the war.
The posted account of Jeff Ethell's ability to "At 100 mph I could hang the P38 on it's props, feet on the floor and gently move the rudder slide side to side.", is a perfect example of what we referring to when we say the P-38 was able to 'hang on its props'. Can't really ask for a better example of the slow speed handling of the P-38 in the vertical when most other planes would have stalled out far sooner.
No one said the maneuver that Erv Ethell used to use was a 'special' P-38 tactic, we all know that spiral climb ropes are common, however, it was a maneuver that was successful by exploiting the better vertical performance of the P-38.
Now, I have no clue as to what you think 'hanging on its props' mean but from everyone's post describing it, it appears that everyone else but you understands what it means.
ack-ack
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Can't think of a single engine fighter where you could be hanging on the prop at 100mph moving rudder from side to side.
A real life Bf 109G has been described to be able to "hang on its prop" at low speeds with a high angle, not sure about the imaginary one though...
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A real life Bf 109G has been described to be able to "hang on its prop" at low speeds with a high angle, not sure about the imaginary one though...
Ultimately, this term is one of the more subjective descriptors among aircraft. Almost any aircraft with a high power loading can "hang" on its prop, as long as the pilot maintains coordinated flight. I bet Dale has a very hard time getting his RV-8 to do a power on stall at anything less than extreme angles of attack.
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Ultimately, this term is one of the more subjective descriptors among aircraft. Almost any aircraft with a high power loading can "hang" on its prop, as long as the pilot maintains coordinated flight.
Totally agreed.
The reason I specifically mentioned 109G was that quote from Jeff Ethell and how his imaginary 109 foe "stalled violently" before his P-38. :D Let's just say it made me chuckle just a tad. :rofl I'm quite sure that for pretty much every WWII fighter, the highest sustainable climbing angle is higher than the one producing the optimal climb rate at any given altitude. It's of course true that the benefits that come from the handed engines definately help the P-38 at this type of situations.
Regarding the Bf 109G,
Finnish Air Force test pilot, Pekka Kokko (13 1/3 kills flying Brewsters, not imaginary) described 109G to be able "hang on its prop" with the speed indicator showing speed of 81-87mph (130-140km/h). With power off, 109G stalled at around 106mph in clean configuration.
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Stoney:
I bet Dale has a very hard time getting his RV-8 to do a power on stall at anything less than extreme angles of attack.
It is down right bizzar. As you start adding the power maintaining stall speed and alt you end up about 70-75 deg before the buffet hits.
But also the higher power aircraft have a harder time producing the thrust to weight at slower speeds (I.E. below best climb) then something like an RV or Extras.
For some reason it just reminded me of the first time my airspeed indicator stuck, was in a hammer head. Not sure if you have done them, but they are a head in & out of cockpit procedure to hit the correct airspeed and maintain the vertical line for the rudder kick.
Im watch the speed drop then it stops about 80, I don't really notice it is stuck but stick was getting soft when all of a sudden I realized what was happening. I still have no desire to tail slide that plane.
Dale