Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: save on June 19, 2014, 08:13:02 PM
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In Aces High I see some stunts, like loops Immelmans done by mainly 2-engine bombers with bomb-load, and rolls (and shift to different plane to warp the drones) on 4-engined planes.
What would happen if you did this in a RL A-20, TU-2, and also rolls in the 4-engined planes with bombs ?
Worst (or best) is by far the A-20, not only doing 4-g turns, but also barrel-rolls and Split-S outperforming some fighters at combat speed.
Should not structural strength be too much for those planes ?
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In Aces High I see some stunts, like loops Immelmans done by mainly 2-engine bombers with bomb-load, and rolls (and shift to different plane to warp the drones) on 4-engined planes.
What would happen if you did this in a RL A-20, TU-2, and also rolls in the 4-engined planes with bombs ?
Worst (or best) is by far the A-20, not only doing 4-g turns, but also barrel-rolls and Split-S outperforming some fighters at combat speed.
Should not structural strength be too much for those planes ?
In an A-20, you'd run the risk of being pulled off flight duties or maybe worse for doing aerobatics in the plane, loaded or unloaded. Aerobatics were strictly forbidden in the A-20.
ack-ack
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Tex Johnson doing a barrel roll in a 707:
http://www.youtube.com/watch?v=-KNbKFMBsQE
This page talks about Lancaster's and the "corkscrew" maneuver.
http://www.pprune.org/archive/index.php/t-265425.html
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Those type of maneuvers would most likely over stress the bomb racks and result in loose bombs in the internal bomb bays and/or separate the externally mounted bombs from the racks.
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One A-20 pilot told me that his training group were told that the wings would fall off if they rolled inverted.
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Here is a story I heard from a B-17 pilot.
He was on a bomb run into the heart of Germany. Prior to drop, flying through heavy flak, there was an explosion, and he was momentarily knocked senseless. When he regained his senses, he still couldn't see because the cockpit was full of thick condensation mist. That soon cleared, and he found that the B-17 was in a near vertical climb, from which it did a hammerhead and then started down. He pulled it out of the hammerhead and found that all controls seemed still to be working. He got things going straight and level again, and they continued on their bomb run and dropped their bombs. After that, he went back to survey the damage. Just aft of the cockpit is the radio room, and its walls were completely blown out, with blood and bits of meat all over the place. There had been two people in the compartment who were now gone. Behind that was the bomb bay, and after that, the waist gunners and then tail gunners. Aft of the radio room, things looked OK. On the way back, because they had been knocked out of formation, and with extra drag, they lagged behind the formation and got attacked repeatedly by 109's. But they made it back to base. A month later, they got a letter from a POW camp. It turned out that the radioman had survived. He had his parachute off, but when the flak started to get heavy, he went to grab it. At that moment, a flak hit blew up right inside the radio room. The radioman regained consciousness falling through the air with his parachute still clutched in his hand. He put it on, pulled the cord, and drifted down into a farm, where he got stuck in a tree. The farmer stabbed him with a pitch fork, but the wound was not life threatening, and then he was captured and put into a camp.
Here is a story from I heard from a B-29 pilot.
They were flying over Tokyo on a fire-bombing run. The fires generated such intense updrafts that, hitting one, his B-29 was slammed up several thousand feet and inverted. To get out of it, he ended up pulling through a split S to recover.
I've read stories of Lancasters doing rolls and split s'es, sometimes as the result of overzealous corkscrew maneuvers (which was a standard by which they evaded night fighters) or as a result of hitting strong updrafts from fires.
Also, you can see videos on youtube of B-17's tumbling or doing vertical dives into recoveries. I think that the bombers had a lot of strength. Of course, such maneuvers weren't encouraged, and some resulted in bending the airframe. Some (the ones we didn't hear about) might have resulted in the plane coming apart.
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Those type of maneuvers would most likely over stress the bomb racks and result in loose bombs in the internal bomb bays and/or separate the externally mounted bombs from the racks.
Rolling pullouts are typically the critical design condition for bomb racks, with wing mounted external stores usually seeing the worst of it because of the lateral load component due to rolling. Also, it's usually the bomb lugs themselves, and not the sway braces or the rack structure that fails.
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Good point. A rolling pull out is also hard on the aircraft structure.
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Consult MIL-STD-8591 for more info than you ever possibly wanted on the subject. :)
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The layout of the bomber you described is not a B-17. The radio room in the B-17 is aft of the bomb-bay. The bomb-bay is directly aft of the cockpit. The radio room of the B-17 is about the only place a tall person can stand in a B-17 without ducking down, it's also quite spacious. Why would the radioman not have his parachute on, or at least stored in the radio room? The only two people in the B-17 who did not regularly wear parachutes were the ball turret gunner and the tail gunner (source of parachute info: B-17 tail gunner that worked with my dad).
Now there is a famous case of a B-17 that flew through the propwash of another B-17 while climbing through clouds. It ended up performing a full loop. IIRC, it had a full bomb load. A quick search on google will bring it up.
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The layout of the bomber you described is not a B-17. The radio room in the B-17 is aft of the bomb-bay. The bomb-bay is directly aft of the cockpit. The radio room of the B-17 is about the only place a tall person can stand in a B-17 without ducking down, it's also quite spacious. Why would the radioman not have his parachute on, or at least stored in the radio room? The only two people in the B-17 who did not regularly wear parachutes were the ball turret gunner and the tail gunner (source of parachute info: B-17 tail gunner that worked with my dad).
Now there is a famous case of a B-17 that flew through the propwash of another B-17 while climbing through clouds. It ended up performing a full loop. IIRC, it had a full bomb load. A quick search on google will bring it up.
I've talked a guy that had over 30 missions in B-17s and had his log to prove it. He argued with me that the B17G I was flying was an F model. Sometimes the years hasn't been kind and the memory is a little fuzzy.
Why would he not have his parachute on? Have you ever tried to do anything with a belly mount parachute on? PITA
It was common that none of the crew wore parachutes using the clip on chest mount. (They were wearing the harness). When the backpack parachutes started being used the pilots, Nav and bombardier normally wore them. As you said tail, ball couldn't (I met a ball gunner that did take the chest mount in the turret with him, his plan if needed was to open the hatch and fall out clipping the parachute on in freefall ). I never tried it but doubt the top turret gunner would be able to wear a parachute, it is very snug in the top turret of both the B-17 and B-24.
I have to wonder about the loop after flying through prop wash. Split S would make sense.....the "prop wash" rolls you inverted, split s to recover. (Rolling upright would suck, the B-17 has a very slow roll rate, I think doing a roll in it would be challenging)
Regarding the B-17 and B-24 doing acro IMO the high control forces would be a huge issue. Just to flare the B-24 for landing takes a lot of muscle on the yoke, at high speed it would be a challenge. B-17 has a lighter elevator than the B-24 but it too has substantial control forces. IMO you would have to quickly get things under control before forces became high enough that you couldn't recover.
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Regarding the B-17 and B-24 doing acro IMO the high control forces would be a huge issue.
This is my biggest gripe with what I see in-game. Sure, the airframe is probably designed for 3 g's limit/ 4.5 g's ultimate, but the control forces are huge. There's a reason why there are two guys flying these beasts. And yet we routinely see "Blue Angels BS" from buff drivers in-game.
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whats the difference between a p-38 with 2 1000 lb bombs on the wings verses an A-20 with 4 500 lb bombs on the wings ?
or a mossi or a 110 ?
i know for a fact that wings come off of A-20 alot easyer when you have bombs strapped on vs empty,is this same true for 38 ?
i dont think i recall ever ripping wings off a 38 that was heavy trying to do a hard G turn,but if you try it in a A20 you are back in tower.
so, i would say that there is definatly a differance between modeling with bomb load compared to no bomb load.
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The layout of the bomber you described is not a B-17. The radio room in the B-17 is aft of the bomb-bay. The bomb-bay is directly aft of the cockpit. The radio room of the B-17 is about the only place a tall person can stand in a B-17 without ducking down, it's also quite spacious. Why would the radioman not have his parachute on, or at least stored in the radio room? The only two people in the B-17 who did not regularly wear parachutes were the ball turret gunner and the tail gunner (source of parachute info: B-17 tail gunner that worked with my dad).
Now there is a famous case of a B-17 that flew through the propwash of another B-17 while climbing through clouds. It ended up performing a full loop. IIRC, it had a full bomb load. A quick search on google will bring it up.
I am speaking from memory of a talk, and as you say I have the name of that compartment wrong -- it is the flight-engineer/top-turret-gunner position. Regardless, there were two guys in it at the time, one of them being the radioman, and the rest of the story is how it was related.
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Wing failure loads are probably another one of those things HTC had to make an educated guess on some planes.
If someone had documented numbers like Maximum G load at load-out I am sure they would use that if they had not already.
It could be though the bombers fuel pickup would shut the engines off in a negative G situation. Colombo can probably answer that.
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whats the difference between a p-38 with 2 1000 lb bombs on the wings verses an A-20 with 4 500 lb bombs on the wings ?
or a mossi or a 110 ?
i know for a fact that wings come off of A-20 alot easyer when you have bombs strapped on vs empty,is this same true for 38 ?
i dont think i recall ever ripping wings off a 38 that was heavy trying to do a hard G turn,but if you try it in a A20 you are back in tower.
so, i would say that there is definatly a differance between modeling with bomb load compared to no bomb load.
Yes, AH breaks the wings at a given amount of force. Same G load with more weight means more lift is produced by the wings, so 6G in an empty plane may be fine, but 6G in a fully loaded plane will break the wings. Pulling high G in the Mossie with 2*500 in the bay is dangerous, especially with more than 50% fuel on board. I broke my wings many times.
The distribution of the weight is supposed to matter in RL, but I do not know how the game handles it. In principle, putting all the weight in the center (bomb bay) will increase the load on the wing root, as opposed to distributing some of the weight to the wings. So in principle, carrying bombs in the bay will make the wings more prone to bending and breaking at a certain G , than hanging the same load on the wings (and an empty bay). This is another reason for a variable pitch angle along the wing (and prop blades) so the root has a higher AoA than the tip - to distribute the stress along the wing and make it bend less. Again, I do not know if AH takes this into account or simply use a threshold for the total lift produced by the wing. By this logic, the P-38 with bombs hanging from the wing roots will suffer less at high G than A-20 with a lot of weight in the bomb bay. Then one has to factor in the actual construction of the wing to figure out how much stress can the wing root take.
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A pilot and engineer on F-16.net claims that carrying bombs on the wings actually reduces the force on the wing when doing maneuvers. So as the angle of attack increases, the wing generates more lift (ultimately creating so much lift that it exceeds its ultimate strength). The weight of the bombs are in the opposite direction of this lift.
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Yes, AH breaks the wings at a given amount of force. Same G load with more weight means more lift is produced by the wings, so 6G in an empty plane may be fine, but 6G in a fully loaded plane will break the wings. Pulling high G in the Mossie with 2*500 in the bay is dangerous, especially with more than 50% fuel on board. I broke my wings many times.
The distribution of the weight is supposed to matter in RL, but I do not know how the game handles it. In principle, putting all the weight in the center (bomb bay) will increase the load on the wing root, as opposed to distributing some of the weight to the wings. So in principle, carrying bombs in the bay will make the wings more prone to bending and breaking at a certain G , than hanging the same load on the wings (and an empty bay). This is another reason for a variable pitch angle along the wing (and prop blades) so the root has a higher AoA than the tip - to distribute the stress along the wing and make it bend less. Again, I do not know if AH takes this into account or simply use a threshold for the total lift produced by the wing. By this logic, the P-38 with bombs hanging from the wing roots will suffer less at high G than A-20 with a lot of weight in the bomb bay. Then one has to factor in the actual construction of the wing to figure out how much stress can the wing root take.
What you're talking about is minimizing bending moments (and hence bending stresses) by distributing the load (either payload, fuel, or airframe mass) over the span of the wing. The trick is to minimize the separation between the aerodynamic forces (lift) and the opposing inertial forces (payload). Doing so keeps wing bending moments from building up. This is one of the structural advantages of flying wings.
The wing "variable pitch" you're referring to is called washout, and it typically has nothing to do with distributing wing loads. Washout is a design feature which allows the wing to stall "gracefully" at max Alpha while still allowing aileron effectiveness. it does help minimize root bending moments at the limit, but this benefit is purely secondary.
I'm guessing that in order to simplify the modeling of airframe failure, HT is simply using load factor vs aircraft weight, with a failure point for each airframe modeled.
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A pilot and engineer on F-16.net claims that carrying bombs on the wings actually reduces the force on the wing when doing maneuvers. So as the angle of attack increases, the wing generates more lift (ultimately creating so much lift that it exceeds its ultimate strength). The weight of the bombs are in the opposite direction of this lift.
The guy is right. As I said earlier, the only downside to carrying stores on the wings is the additional inertial loading due to rolling maneuvers. This is typically the designing load condition for wing mounted bomb racks and their attachments to the wing itself.
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Here is a story from I heard from a B-29 pilot.
They were flying over Tokyo on a fire-bombing run. The fires generated such intense updrafts that, hitting one, his B-29 was slammed up several thousand feet and inverted. To get out of it, he ended up pulling through a split S to recover.
Pilot Gordon Bennett Robertson Jr.'s first fire-bomb run over Tokyo in March, 1945 took him through boiling thermals produced by the burning city 5,000 feet below. They bounced his B-29 up and down and then flipped the sixty-ton bomber onto its back. He was able to recover only through a Split-S maneuver he'd practiced flying fighters in training.
Barrett Tillman tells this story in his book Whirwind
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In an A-20, you'd run the risk of being pulled off flight duties or maybe worse for doing aerobatics in the plane, loaded or unloaded. Aerobatics were strictly forbidden in the A-20.
ack-ack
Of course, the USAAF didn't want inexperienced pilots killing themselves. That, however, doesn't mean that the A-20 wasn't capable of impressive aerobatics. It was stressed to 5g positive and 2g negative at max takeoff weight. Ultimate strength was closer to 7g.
Ever watch Bob Hoover do his demonstration in his Shrike Commander?
https://www.youtube.com/watch?v=PftNh_SShlg (https://www.youtube.com/watch?v=PftNh_SShlg)
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Pilot Gordon Bennett Robertson Jr.'s first fire-bomb run over Tokyo in March, 1945 took him through boiling thermals produced by the burning city 5,000 feet below. They bounced his B-29 up and down and then flipped the sixty-ton bomber onto its back. He was able to recover only through a Split-S maneuver he'd practiced flying fighters in training.
Barrett Tillman tells this story in his book Whirwind
From the B-29 manual... I'm sure he pulled it off, but the airframe isn't really designed for it. He probably yielded the structure in the process. Sure as Hell beats dying though
(http://i1292.photobucket.com/albums/b570/happyfluffycthulhu/Mobile%20Uploads/B-29%20Flight%20manual_zpssny732o3.gif)
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Of course, the USAAF didn't want inexperienced pilots killing themselves. That, however, doesn't mean that the A-20 wasn't capable of impressive aerobatics. It was stressed to 5g positive and 2g negative at max takeoff weight. Ultimate strength was closer to 7g.
Ever watch Bob Hoover do his demonstration in his Shrike Commander?
https://www.youtube.com/watch?v=PftNh_SShlg (https://www.youtube.com/watch?v=PftNh_SShlg)
Widewing, do you know definitively what limit load was for the heavies? 5g's sounds perfect for the A-20, but I'd be surprised if the big guys were designed to that level.
And btw, what always blew me away about Hoover was what he did with the glass of water. :)
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http://www.youtube.com/watch?v=-dOu674barc (http://www.youtube.com/watch?v=-dOu674barc)
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What a bomber does with the bombs unloaded I can understand (example the A20).
Doing the same with half tanks filled, and bombs is what I want to prevent, if they could not do it RL.
The 500mph dives in formation should be subjected to losing drones in my opinion.
The rolling and switching planes to warp the drones should take at least the same penalty.
Shooting with any accuracy over say 2G should be prevented to give the AH fidelity the company claim.
Thanks for a good and civil discussion :salute
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Widewing, I have another question. This is shown in the B-29 manual table for stall speed vs weight for various flap positions. What's your take on this?
WARNING: DO NOT STALL THE AIRPLANE WITH THE COWL FLAPS OPEN MORE THAN 10°
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1G is 1G and it does not matter one bit what the view from the cockpit is.
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Barrett Tillman tells this story in his book Whirwind
Hmm. I might have read it then instead of hearing it, or it could have been from the talk Barrett Tillman gave at the Museum of Flight.
The Museum of Flight has had a lot of panels with WWII pilots. I've listened to about 75 WWII pilots talk over the years there, and there have been amazing stories. One was a panel of B-29 pilots. One was a panel of pilots and Barrett Tillman. Others have been with pilots of P-51's, P-47's, P-38's, P-40's, P-39's, Mossies, B-17's, B-24's, B-25's, F4U's, F6F's, TBM's, and Spitfires, but I missed my chance to talk to an Me 262 pilot.
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1G is 1G and it does not matter one bit what the view from the cockpit is.
Would you care to elaborate on that pontification?
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Would you care to elaborate on that pontification?
If you keep the loading at 1G through whatever maneuver you are doing it doesn't matter to the aircraft where the center of the local gravity well is. The trick is keeping the G loading close to 1 through a roll or loop or what not.
The comment I referenced earlier about what the A-20 pilots were told, that the wings would fall off if they rolled it inverted, I have no doubt was simply a falsehood to encourage them to not try aerobatics in their A-20s.
As to laden maneuvering, Lancasters did perform the corkscrew evasive with bombs on board.
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Hmm. I might have read it then instead of hearing it, or it could have been from the talk Barrett Tillman gave at the Museum of Flight.
The Museum of Flight has had a lot of panels with WWII pilots. I've listened to about 75 WWII pilots talk over the years there, and there have been amazing stories. One was a panel of B-29 pilots. One was a panel of pilots and Barrett Tillman. Others have been with pilots of P-51's, P-47's, P-38's, P-40's, P-39's, Mossies, B-17's, B-24's, B-25's, F4U's, F6F's, TBM's, and Spitfires, but I missed my chance to talk to an Me 262 pilot.
Bet that was great seeing/hearing Tillman speak. :aok
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Widewing, I have another question. This is shown in the B-29 manual table for stall speed vs weight for various flap positions. What's your take on this?
WARNING: DO NOT STALL THE AIRPLANE WITH THE COWL FLAPS OPEN MORE THAN 10°
:airplane: In the 29, we never did any kind of stalls unless, first, close cowl flaps completely, as they tend to "blank" out the effect of the elevator!
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Would you care to elaborate on that pontification?
:airplane: While I did not make the comment, maybe I can clear up a couple of points. #1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G. "Tex" Johnson pulled off the famous "barrel roll" in the Boeing 707, because he understood that as long as he was pulling 1.5 g's, he could sit a glasses of water on the instrument panel and it would not overturn. He understood the effect of "g" forces and how they affected the aircraft in flight. The roll it did, put no more stress on the aircraft than if it was flying straight and level.
Comment about the bomb loads on wings and their effect! The wing of an aircraft is designed to support a certain amount of weight and if you exceed that weight, you stand a good chance of wing failure. Example: If your 51D weights 13,500 lbs at takeoff weight, full fuel tanks, drop tanks and rockets, the add 2 1,000 lb bombs, you now have in effect a wing which is designed to carry no more than 13,850 lbs, which now weights 15, 500 lbs, you now are flirting with structural failure, if you add any "g" force, plus or minus because of the additional weight that the wing now has to support.
Don't confuse the antic's of these make believe aircraft in this game with the real thing, because in most cases, you would have structural failure. Now, that is not to say that a lot of strange things have not happened to aircraft in flight, because we all know, those things do happen and if we knew how forces were applied by chance and God's guiding hand, then we would understand how the crews lived through the incidences.
Good post and some good comments though!
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:airplane: In the 29, we never did any kind of stalls unless, first, close cowl flaps completely, as they tend to "blank" out the effect of the elevator!
Thanks Earl, I thought that's what it was, but I wanted to hear from someone more familiar with the 29.
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:airplane: While I did not make the comment, maybe I can clear up a couple of points. #1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G. "Tex" Johnson pulled off the famous "barrel roll" in the Boeing 707, because he understood that as long as he was pulling 1.5 g's, he could sit a glasses of water on the instrument panel and it would not overturn. He understood the effect of "g" forces and how they affected the aircraft in flight. The roll it did, put no more stress on the aircraft than if it was flying straight and level.
Comment about the bomb loads on wings and their effect! The wing of an aircraft is designed to support a certain amount of weight and if you exceed that weight, you stand a good chance of wing failure. Example: If your 51D weights 13,500 lbs at takeoff weight, full fuel tanks, drop tanks and rockets, the add 2 1,000 lb bombs, you now have in effect a wing which is designed to carry no more than 13,850 lbs, which now weights 15, 500 lbs, you now are flirting with structural failure, if you add any "g" force, plus or minus because of the additional weight that the wing now has to support.
Don't confuse the antic's of these make believe aircraft in this game with the real thing, because in most cases, you would have structural failure. Now, that is not to say that a lot of strange things have not happened to aircraft in flight, because we all know, those things do happen and if we knew how forces were applied by chance and God's guiding hand, then we would understand how the crews lived through the incidences.
Good post and some good comments though!
I've been a structural engineer with first General Dynamics, and now Lockheed Martin for the last 36 years. (Now they're the same company and the b@stards won't bridge my years of service #! $@*&#! ) Anyway, this is a subject which I feel compelled to weigh in on every time it comes up, because there's a lot of incomplete information, or outright BS floating around.
Thanks Earl for helping to explain the subject. :salute
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Thanks Earl, I thought that's what it was, but I wanted to hear from someone more familiar with the 29.
I would imagine that this was quite a disturbing discovery for the test pilot who stumbled upon it for the first time......
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:airplane: While I did not make the comment, maybe I can clear up a couple of points. #1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G. "Tex" Johnson pulled off the famous "barrel roll" in the Boeing 707, because he understood that as long as he was pulling 1.5 g's, he could sit a glasses of water on the instrument panel and it would not overturn. He understood the effect of "g" forces and how they affected the aircraft in flight. The roll it did, put no more stress on the aircraft than if it was flying straight and level.
Comment about the bomb loads on wings and their effect! The wing of an aircraft is designed to support a certain amount of weight and if you exceed that weight, you stand a good chance of wing failure. Example: If your 51D weights 13,500 lbs at takeoff weight, full fuel tanks, drop tanks and rockets, the add 2 1,000 lb bombs, you now have in effect a wing which is designed to carry no more than 13,850 lbs, which now weights 15, 500 lbs, you now are flirting with structural failure, if you add any "g" force, plus or minus because of the additional weight that the wing now has to support.
Don't confuse the antic's of these make believe aircraft in this game with the real thing, because in most cases, you would have structural failure. Now, that is not to say that a lot of strange things have not happened to aircraft in flight, because we all know, those things do happen and if we knew how forces were applied by chance and God's guiding hand, then we would understand how the crews lived through the incidences.
Good post and some good comments though!
Yup. Different aircraft designs have different failure points. I seem to recall that for the USAAF fighters were supposed to be able to handle 11 Gs when combat loaded. If combat loaded for the P-51D is 10,000lbs, that would mean an 110,000lb structural failure point. Load it up with bombs and rockets and you'll hit that 110,000lb mark at well under 11 Gs.
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I would imagine that this was quite a disturbing discovery for the test pilot who stumbled upon it for the first time......
Disturbing is putting it mildly. lol
Reminds me of the first test flights of one of the later Japanese fighters (can't remember which one). The test pilot was climbing out, raised the gear, and the plane promptly nosed over and crashed, killing the pilot. Soon after, another test pilot repeats the process in a second aircraft, complete with fatal crash. The THIRD test pilot tries his luck, but he has the good sense to climb to about 5k before raising the gear. Sure enough, the moment he raises the gear, hard nose over! But this guy has the time, and altitude to drop the gear, and the hard pitch over disappeared. So the guy lands, and tells the engineers what he thinks is the problem. Sure enough, there was an interference with the retractable tail wheel and the bell crank on the elevator hinge. The tail wheel would come up and jam the elevator hard nose down!
Now if I could just remember which plane it was. I read that story in one of William Green's books.
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:airplane: In the 29, we never did any kind of stalls unless, first, close cowl flaps completely, as they tend to "blank" out the effect of the elevator!
On the B-24 if the cowl flaps were left open instead of in trail for takeoff you would get buffeting. There was a crew during the war stateside that bailed from a new B-24 because of unexplained buffeting, turned out to be cowl flaps open.
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On the B-24 if the cowl flaps were left open instead of in trail for takeoff you would get buffeting. There was a crew during the war stateside that bailed from a new B-24 because of unexplained buffeting, turned out to be cowl flaps open.
Now there's a guy who was looking at a career change once his tour ran out. :)
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On the B-24 if the cowl flaps were left open instead of in trail for takeoff you would get buffeting. There was a crew during the war stateside that bailed from a new B-24 because of unexplained buffeting, turned out to be cowl flaps open.
:airplane: When taking off at Tinian, it was standard practice to close cowl flaps completely beginning takeoff roll, then as we passed 135knots on climb out would go to what ever engineer decided on, which was usually wide open, but at that high of speed, we still would have buffering on the elevators. Those big old R-3350 compounds would heat up in a heartbeat and if they did, we would level after takeoff, just to cool them down before starting a long climb. Sometimes during climb, we would level for cooling purposes.
(http://i1120.photobucket.com/albums/l488/05263739/110581mb29.jpg)
(http://i1120.photobucket.com/albums/l488/05263739/29withcowlflapsclosed.jpg)
not sure if these are good pic's of cowl flap positions but I tried to find some.
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:airplane: When taking off at Tinian, it was standard practice to close cowl flaps completely beginning takeoff roll, then as we passed 135knots on climb out would go to what ever engineer decided on, which was usually wide open, but at that high of speed, we still would have buffering on the elevators. Those big old R-3350 compounds would heat up in a heartbeat and if they did, we would level after takeoff, just to cool them down before starting a long climb. Sometimes during climb, we would level for cooling purposes.
(http://i1120.photobucket.com/albums/l488/05263739/110581mb29.jpg)
(http://i1120.photobucket.com/albums/l488/05263739/29withcowlflapsclosed.jpg)
not sure if these are good pic's of cowl flap positions but I tried to find some.
Earl, any idea if the problem was even worse on the B-50? I'm thinking it would be.
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Earl, any idea if the problem was even worse on the B-50? I'm thinking it would be.
:airplane: All I know about the B-50 are just things I heard! But I would guess that it was a serious problem to, because the B-50 had the P&W R-4360 engine, which was much larger than the 3350 and I would think the cowl flap openings were larger, but don't really know.
(http://i1120.photobucket.com/albums/l488/05263739/b-50cowlflaps.jpg)
not a very good pic, have not learned how to enlarge photo's that I copied on line yet, maybe someone can tell me.
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Now there's a guy who was looking at a career change once his tour ran out. :)
The way those things tended to go, the guy probably made all his future promotions and retired as a general officer. ;)
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:airplane: While I did not make the comment, maybe I can clear up a couple of points. #1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G. "Tex" Johnson pulled off the famous "barrel roll" in the Boeing 707, because he understood that as long as he was pulling 1.5 g's, he could sit a glasses of water on the instrument panel and it would not overturn. He understood the effect of "g" forces and how they affected the aircraft in flight. The roll it did, put no more stress on the aircraft than if it was flying straight and level.
Comment about the bomb loads on wings and their effect! The wing of an aircraft is designed to support a certain amount of weight and if you exceed that weight, you stand a good chance of wing failure. Example: If your 51D weights 13,500 lbs at takeoff weight, full fuel tanks, drop tanks and rockets, the add 2 1,000 lb bombs, you now have in effect a wing which is designed to carry no more than 13,850 lbs, which now weights 15, 500 lbs, you now are flirting with structural failure, if you add any "g" force, plus or minus because of the additional weight that the wing now has to support.
Don't confuse the antic's of these make believe aircraft in this game with the real thing, because in most cases, you would have structural failure. Now, that is not to say that a lot of strange things have not happened to aircraft in flight, because we all know, those things do happen and if we knew how forces were applied by chance and God's guiding hand, then we would understand how the crews lived through the incidences.
Good post and some good comments though!
Since each additional g adds the total aircraft weight to the wing load you just have to reduce max g by 2.5 to stay within the wing limit for the P-51. Not saying something else won't break.
If you keep the loading at 1G through whatever maneuver you are doing it doesn't matter to the aircraft where the center of the local gravity well is. The trick is keeping the G loading close to 1 through a roll or loop or what not.
Good luck flying a 1g loop. I hope you mean keep some positive g when inverted. :D
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#1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G.
When jumping in the air you are in free-fall, hence 0 G, not negative. Negative G would be jumping into the air with a rubber band stretching after you and pulling you down in addition to gravity.
Just sayin'
Since each additional g adds the total aircraft weight to the wing load you just have to reduce max g by 1 to stay within the wing limit.
Good luck flying a 1g loop. I hope you mean keep some positive g when inverted. :D
You can fly a loop and keep positive G through it. For example, you can start with a 3G pull, down to 2G when crossing the vertical and 1G when inverted, then build up G again as you accelerate downward on the other side. This way you have a constant 2G centripetal acceleration throughout, and keep G positive. However the loss of speed in the climb will not make this a perfect circle - more like an inverted Greek gamma shape.
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There is no negative g, it's just a different vector. ;)
You don't need 1 g inverted, any radial g will keep you in the seat.
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Since each additional g adds the total aircraft weight to the wing load you just have to reduce max g by 1 to stay within the wing limit.
Good luck flying a 1g loop. I hope you mean keep some positive g when inverted. :D
:airplane: I never said anything about a 1 g roll, but have done many 1.5 g barrel rolls, which is very easy to do. If you are not pulling at least a 1/2 G, every loose object in the aircraft is going to fly up in your face, including the dirt and dust in the floor.
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Bet that was great seeing/hearing Tillman speak. :aok
It was, and I was really grateful that he showed up to moderate one of the discussion panels.
Also, many of the pilots' stories have been absolutely amazing. I've heard stories from combat pilots of most of the US combat aircraft in WWII (P-51, P-47, P-38, P-40, F4U, F6F, TBM, SBD, B-29, B-17, B-24, B-25, P-61) and some RAF planes (Spitfire, Mosquito, Beaufighter, Wellington), pilots who gained aces status in P-51's (Bud Anderson and others), P-47's (Steve Pisanos, George Novotny, and others), P-38's (George Chandler and others), F6F's (Hamilton McWhorter and others), F4U (Dean Caswell and others), and the Mosquito (Lou Luma), every theater, pilots who participated in the Battle of Midway (including Harry Ferrier, who was on the only TBM to make it back to Midway), the Marianas (F6F pilots and TBM pilot Warren Omark, who put a torpedo into the Hiyo), Market Garden (Spitfire pilot Witold Herbst), North Africa, bombing Tokyo, over Germany, France, and Italy, different roles (fighter, fighter-bomber, divebomber, torpedo bomber, bomber, recon), a guy who was on the USS Bunker Hill when it was hit by the kamikazes, a guy who shot down an Me 262 (Clayton Gross), a guy who shot down an Me 163 (Art Jeffrey).
The Museum of Flight near Seattle has been an amazing place. I feel very lucky.
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When jumping in the air you are in free-fall, hence 0 G, not negative. Negative G would be jumping into the air with a rubber band stretching after you and pulling you down in addition to gravity.
Just sayin'
You can fly a loop and keep positive G through it. For example, you can start with a 3G pull, down to 2G when crossing the vertical and 1G when inverted, then build up G again as you accelerate downward on the other side. This way you have a constant 2G centripetal acceleration throughout, and keep G positive. However the loss of speed in the climb will not make this a perfect circle - more like an inverted Greek gamma shape.
:airplane: OK, now I am confused! Are you saying that if you are inverted and you push forward on stick, you will not be pulling a negative G? I believe it was Einstein, who while talking about relativity, stated that anything that moves away from the center of the earth, is in effect, in a negative G situation., Hence, if you jump off the ground, as you are going up, you are in a negative situation. Maybe that was a poor analogy I used, but the principal is the same. Now if you are doing a spilt S, while you are not working aginst gravity, you now have centrfical force which comes into play, which applies G forces, but is generated in a different way.
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:airplane: I never said anything about a 1 g roll, but have done many 1.5 g barrel rolls, which is very easy to do. If you are not pulling at least a 1/2 G, every loose object in the aircraft is going to fly up in your face, including the dirt and dust in the floor.
Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.
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Guys, the uses of "g's" to describe the magnitude of inertial loads (and that's what maneuvering loads are) is purely a convention. The presence, or absence, of a gravitation field while you're making those maneuvers is largely secondary. You can pull a 100 g turn in the void of space (well your vehicle could..... you'd be a lump of Jello on the floor :( )
Yes you can do a loop and experience zero "g" at the top (but only within a gravitaion field like the Earth's), but it will only be for a moment.
Yes, there is such a thing as negative g's, but it's just another convention (a reversal of the longitudinal acceleration vector relative to the coordinate system of the aircraft as FLS said).
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Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.
:airplane: Sorry sir! My bad, I always enjoy your posts and :salute you do for training people in this great game!
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:airplane: Sorry sir! My bad, I always enjoy your posts and :salute you do for training people in this great game!
No worries I've misread a few posts myself. :salute
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:airplane: OK, now I am confused! Are you saying that if you are inverted and you push forward on stick, you will not be pulling a negative G? I believe it was Einstein, who while talking about relativity, stated that anything that moves away from the center of the earth, is in effect, in a negative G situation., Hence, if you jump off the ground, as you are going up, you are in a negative situation. Maybe that was a poor analogy I used, but the principal is the same. Now if you are doing a spilt S, while you are not working aginst gravity, you now have centrfical force which comes into play, which applies G forces, but is generated in a different way.
I never said anything about pushing the stick. What I said translates to "you can yank on the stick and keep G>1 throughout the loop", but it will not come out like a nice circle. Easy to demonstrate in AH, every spit 2-weeker does it as his main ACM.
0G means free-fall. The direction of travel makes no difference - a stone thrown upward is at free-fall even when it is still going up. For a pilot like yourself: G=L/Mg using just scalar numbers and regardless of the gravity vector. Everything that is traveling through the air and does not produce lift (L=0) is pulling 0G and flies ballisticly. So, if you jump up off the ground you are at 0G till you hit the ground again.
Now regarding relativity - in general relativity, being "stationary" means 0G, i.e. free-fall. So, if you are NOT falling and are standing on solid ground you are actually accelerating "up" from earth at 1g (lower case "g"=10 m/s^2 and has nothing to do with "lift" in the aeronautical sense). You can call this negative acceleration if you define the positive direction towards the earth's center, so you are now at -1g and are moving away from earth's center in space-time.
General relativity originated from the notion that locally one cannot distinguish between gravity and acceleration, hence "gravity" is in practice acceleration. Ironically, Einstein's theory that is supposed to explained gravity does not have a gravitational force in it at all.
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Aren't you guys just disagreeing about your frame of reference? After you jump you decelerate, stop, and accelerate in the opposite direction until the ground stops you. As Cthulhu pointed out 0 g refers to load factor. We are always subject to gravity.
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Aren't you guys just disagreeing about your frame of reference? After you jump you decelerate, stop, and accelerate in the opposite direction until the ground stops you. As Cthulhu pointed out 0 g refers to load factor. We are always subject to gravity.
To attain zero g, you must descend at the rate of gravity. This can be seen using an strain gauge type accelerometer w/amplifier and an Oscilloscope. Attach the accelerometer to something you can simply let fall. We use vertical drop test machines for testing dynamic response to impacts. While sitting in normal gravity, the accelerometer will have a voltage output that equates to 1g. When it is released, the output voltage nearly goes to zero. It can never attain zero, because there are always factors preventing it. Aero drag, very slight friction on the Teflon guide bushings, etc, all contribute to not dropping at the rate of gravity. It comes very close, though.
An aircraft can attain zero g by easing nose down and losing altitude at the rate of gravity. Fighter pilots call this, "unloading". It minimizes induced drag and maximizes acceleration with minimal loss of altitude.
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To attain zero g, you must descend at the rate of gravity. This can be seen using an strain gauge type accelerometer w/amplifier and an Oscilloscope. Attach the accelerometer to something you can simply let fall. We use vertical drop test machines for testing dynamic response to impacts. While sitting in normal gravity, the accelerometer will have a voltage output that equates to 1g. When it is released, the output voltage nearly goes to zero. It can never attain zero, because there are always factors preventing it. Aero drag, very slight friction on the Teflon guide bushings, etc, all contribute to not dropping at the rate of gravity. It comes very close, though.
An aircraft can attain zero g by easing nose down and losing altitude at the rate of gravity. Fighter pilots call this, "unloading". It minimizes induced drag and maximizes acceleration with minimal loss of altitude.
I'm surprised you didn't use the "Vomit Comet" as an example of zero g.
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Correct me if I'm wrong, but isn't going up at any rate actually increasing the G's experienced? This being the case, isn't a rock still traveling up still experiencing G>0?
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Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.
I didn't mean to imply that it was possible to do so. I was being overly generic I fear. Any pull out is going to be more than 1G, well, any pull out on Earth. If somebody ever does on on Venus or Titan they will be able to keep it under 1 G if they are gentle enough. :P
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I didn't mean to imply that it was possible to do so. I was being overly generic I fear. Any pull out is going to be more than 1G, well, any pull out on Earth. If somebody ever does on on Venus or Titan they will be able to keep it under 1 G if they are gentle enough. :P
Lightweight.... we wanna see you do a 4 g pullout, on the deck, (if there is a deck) on Jupiter. :D *
* And of course we're talking about the "g" of the host planet.