Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: dirtdart on April 05, 2010, 12:14:00 PM
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Just noticed. Now when you shoot up the feathers, the planes can still maneuver with one Stab. Would that not double the loading on that surface, and make it easier for the plane to come uncoupled? Not sure if this is new, just took notice of it lately.
btw..... PERK THE BREWSTER!
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Wouldn't it just exert half the force?
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wouldn't this just be a video game?
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wouldn't this just be a video game?
Simulation?
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From what I've seen when it's happened to me, which is admittedly only a couple times, if you lose half your horizontal stabilizer it has a large effect on your elevator authority. Almost like it's cut in half.
Wiley.
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Others report being more manuverable than before with 1/2 the stab missing. May be plane dependent.
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Simulation?
Show me where htc promotes the game as a simulation.
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Almost as if................. You only had half the elevator response? WHOA..............You may be right! :cheers:
From what I've seen when it's happened to me, which is admittedly only a couple times, if you lose half your horizontal stabilizer it has a large effect on your elevator authority. Almost like it's cut in half.
Wiley.
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Show me where htc promotes the game as a simulation.
They have always claimed to simulate the aircraft and the performances, and the physics of flying.
They never claimed (and even denied) simulating the war itself.
Sim? Yes. WW2 combat? No.
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depends on which wing also because of prop rotation
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He's not talking about wings. He's talking about tail feathers.
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oh....spitfire(cant remeber the version) also flies better with a stab missing
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Show me where htc promotes the game as a simulation.
Shown.
http://www.hitechcreations.com/gameinfo/gameinfo.html
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Show me where htc promotes the game as a simulation.
Look at the post above me, did you really think that Aces High 2 doesn't fall under the simulation genre of gaming. :huh
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(http://www.allamericanblogger.com/wp-content/uploads/facepalm.jpg)
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Better get the anti troll spray out...
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(http://i160.photobucket.com/albums/t164/zaxtax/258Troll_spray.jpg)
I've noticed this alot too, planes become more agile with a missing stabilizer.
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Yep, same here.
Lose an elevator and your done, lose half the h stab(with the elevator on it) and your more maneuverable...that's interesting. :rolleyes:
Maybe I'm the only one...oh well. :noid
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Noticed my A6M5b becomes a fair bit more instable when I push it to the edge with one H-Stab, not saying thats a bug it kinda makes sense to me. I hadn't noticed an increase in turning ability though.
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Simulation?
er good stimulation fo sho
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question here
Originally when the stabilizer would come off the aircraft would pitch up. With that is it possible that with half the stabilizer tore off it would turn a little better since you have to pull on the elevators to get it to turn after your roll?
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With a H stab missing the plane is less stable. Less stability creates the ability for a more rapid AOA changes. Turn performance would decrease , or possibly remain the same.
With 1 elevator destroyed your turn performance will decrease, it the corrisponding stab is then destroyed your turn performance will go back up. We thought this was a bug until we brought it up in our force vector displayer and saw that what is happening is with 1 side elevator gone and the stab remaining, the stab is fighting the other elevator so you can not generate the AOA you need. Once that stab is removed, the AOA you can generate is restored.
HiTech
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Does that applies at very low speed as well? One stab with one elevator shouldn't be as effective as intact plane at very low speeds.
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to those that jacked this thread for the sim no sim crap... BAH.
From a sim standpoint and an engineering one, the surfaces are designed to carry X load. Certainly they were not designed to carry the full load individually. My point is I thin under heavy maneuvering they would break off. Shot the stab of a 109 and then watch him dive from 10k straight down to the field and land. Seems gamey to me and just an observation.
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to those that jacked this thread for the sim no sim crap... BAH.
From a sim standpoint and an engineering one, the surfaces are designed to carry X load. Certainly they were not designed to carry the full load individually. My point is I thin under heavy maneuvering they would break off. Shot the stab of a 109 and then watch him dive from 10k straight down to the field and land. Seems gamey to me and just an observation.
I have to agree in a sense, but you also have to think of overhead built in. In many cases parts are built to sustain forces much larger then they will probably ever see, just for the sake of being safe then sorry. At least, that'd be my guess.
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to those that jacked this thread for the sim no sim crap... BAH.
From a sim standpoint and an engineering one, the surfaces are designed to carry X load. Certainly they were not designed to carry the full load individually. My point is I thin under heavy maneuvering they would break off. Shot the stab of a 109 and then watch him dive from 10k straight down to the field and land. Seems gamey to me and just an observation.
What "load" do you think they are the carrying?
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Interesting results HiTech but I'd think there's much more to it than that. AFAIK, most, if not all, WWII aircraft had a continuous spar. Remove half the stab and the loads on the remaining side would not only double (for the same turn) but the nature of the load at the stab/fuselage juncture would be completely different. Since there is no counterbalancing lift on one side the pure vertical load would become pure torque, something the stab attachement would not be designed for. Also, you'd lose half of your control power and I'd guess that your stick-force-per-G would shoot up since you'd have to deflect the remaining elevator more to generate the same pitching moment. I can't see a fighter being able to pull the same turn with half a tail plane or to do it without losing the remaining part.
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How would the force double? You have half the elevator creating half the force of the full elevator for the same deflection. Wouldn't full deflection create the same force per side as it did before the damage? Any torque added would be to the airframe not the stab.
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How would the force double? You have half the elevator creating half the force of the full elevator for the same deflection. Wouldn't full deflection create the same force per side as it did before the damage? Any torque added would be to the airframe not the stab.
It would double on the remaining half stab. For the same turn rate the same total downforce would be required but with only half as much surface. I also doubt that in most scenarios there would be sufficient control deflection on the half elevator to generate the required force but that's only my opinion. I have no way to model it. As for the torque you're right that it would be transmitted to the fuselage but it has to be transferred there through the stabilizer/fuselage connection. That is not the type of load it's designed for.
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Sorry, I should have asked how would the max load double. Since the force applied by the elevator is presumably already within the strength limit of the stabilizer I don't see how it would be a problem. I'm assuming the damage to one side isn't affecting the strength of the other side since we're just discussing loads. The only way to get the same turn rate with half a stab would be if half the elevator created enough down force. I don't see how half an elevator could produce double the force of the full elevator unless the full elevator was at less than full deflection to begin with. It seems to me that since the max load is self limited by the elevator the problem would be getting the same turn rate.
Since the load is the same, either up or down, on the stabilizer, the fact that more torque is going to the airframe shouldn't make any difference at the stabilizer attachment point.
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Are you sure the elevator needs a down force, or just less up force.
HiTech
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Are you sure the elevator needs a down force, or just less up force.
HiTech
This is getting confusing. Elevator up to push the tail down to increase the AoA. I'm calling this a down force on the tailplane.
It also seems that with one side missing there would be less torque on the tailplane from the spiral slipstream so the additional torque from the unbalanced tailplane would be mitigated to a degree depending on speed.
I understand Mace's point about torque on the attachment, I just assumed it would be overbuilt in anticipation of battle damage but I don't know enough about the general construction practice and since we don't have a particular aircraft in mind that might vary with the model.
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From my one time experiencing this (Bf-110C lost its left H.Stab), the maneuverability of the aircraft was the same (maybe slightly better) but its stability was terrible. Once I finally recovered from the 110's signature flat spin, I actually managed to maneuver in and kill the player who wounded me, but in stressing the flight path to make the shot I nearly plummeted sideways into the ground right behind him.
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US Planes were designed to a (don't quote me) 8G wheras brits were 6G, no idea on the germans or japanese. The tailplane and spar were designed to carry loads, like a bridge, which correspond to the physical weight they must bear. If you lose half of the load bearing surface area, would the weight and forces not transmit to the only other load bearing surface, the other half. I just don't thin you could dive a plane and pull out without ripping the entire apendage off.
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At 4G you start losing your color eyesight (my IRL experience) at 6G prolonged you will black without G-suit.
My aerobatic experience is very limited to aerobatic gliders ( my ultralight wont me allow me to do any aerobatic at all)
I think 8G would leave most pilot unconscious without G-suit in a snap
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I don't have those experiences Save, just looking at it from an Engineering standpoint. Duly noted BTW.
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Dirtdart by your logic if a sailboat has two sails and you lower one, then the remaining sail has twice the load on it. You're assuming that half the elevator could somehow generate twice the force it produces when there is a full elevator and that it's not built to sustain more than the max force it can produce.
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Sailboat is a bad comparison. The single mast is designed to hold the load of two sails, individually or together as a load bearing structure. The tailplane of an airplane carry a load as it stabilizes the plane as it cruises through the air. Depending on trim and CG settings, speed, et al... the tailplane as one long unit carries the burden. It takes let say 100 lbs of downforce to push the nose up, well if I make the same input requirement with one surface, as opposed to two, because of the reduction in area, the input must be greater. So it would take a bit more than 100 lbs. I think I am going to have to do some research.
This discussion is going to end up having me break out some very old dusty books....lol. :aok
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Think of the two sails as the tailplane/elevators and the fuselage as the mast.
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In order for the plane to sustain a given turn, say 6g, a certain download on the tail is required. This download is spread over the entire surface of the complete horizontal tail. Now, take away half the horizontal tail and that 1/2 surface area must now generate all of the download if the pilot's going to sustain a 6g turn. That means that 1/2 the surface must generate twice it's original load in order to make up for the loss of 1/2 of the total surface area. The sailboat idea is looking at the same thing but from a different perspective. Take away half the surface and 1/2 of the power is produced, i.e., the boat will slow down. To sustain the same speed the remaining sail must be retrimmed to generate twice it's original load. Of course there are big limits to this. Can the remaining horizontal tail surface have enough elevator travel and stall margin to generate twice it's original load? Probably not. Can the remaining sail be trimmed to produce twice the load it was originally? Probably not. This is grossly oversimplified since jibs and mailsails don't generate the same power but I think you get my point.
Also, the distribution of the load is very different. Think of a complete horizontal tail as a teeter totter board with the fuselage/horizontal tail joint represented by the pivot. Lift up equally on both ends of the board and board will not pivot and the load at the pivot point is directly vertical. Now, cutoff one end of the board and lift the other end and it'll pivot because there's no counterbalancing load on the missing end. That's the torque I'm talking about that is transmitted through the fuselage/tail joint. That joint isn't designed to counteract torque, it's primarily designed to carry normal vertical loads. Subject a joint to stresses it's not designed to handle and it'll fail.
Now, HiTech is hinting that there is not an increasing load on the tail for greater G, it could actually be a decreasing load (less upforce). I don't see this but then, like I said before, I don't have a way to model it. From a pilot's perspective there is a measurement that looks at this called stick-force-per-G. In other words, it's how much rearward force the pilot must place on the stick in order to generate greater than 1G. That force must increase for every additional G. Say 2lbs for 2g, 4 lbs for 3g, 7 lbs for 4g, 10 lbs for 5g and 15 lbs for 6g. That's called a positive gradient and that's what you want because it means the pilot must pull harder for every additional G and it gives the pilot a positive sense of what the airplane is doing. A negative gradient where stick-force-per-G declines for greater G is a very bad thing and any fighter that exhibited would probably not be considered safe and would be assigned a PartI deficiency and rejected because it would be very easy to inadvertantly stall or overstress. Note: I'm talking about subsonic planes here, strange things can happen in the trans-sonic region including reduction in stick-force-per-G.
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Wow a post with some actual intelligence to it.
My experience when I have lost the control surface of one elevator AoA suffered greatly, while when I lost the the whole elevator-stabilizer it wasn't nearly as bad with just the control surface missing, but it still wasn't as good as having the full stabilizer. There are some good thoughts on the subject in this thread though, I can see both sides of the debate as logical.
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It takes let say 100 lbs of downforce to push the nose up, well if I make the same input requirement with one surface, as opposed to two, because of the reduction in area, the input must be greater. So it would take a bit more than 100 lbs. I think I am going to have to do some research.
This discussion is going to end up having me break out some very old dusty books....lol. :aok
I think what HiTech was saying is that you don't need 100 lbs of downforce to push the nose up, because the rear stabs are lift surfaces that keep the tail up. To pitch the nose up, then, you need to decrease the lift on the tail, not provide a downforce.
This is why, in the old system where both stabs fell off simultaneously, the plane pitches UP, not noses down.
This is easier to do when an entire stab is missing rather than just the elevator, hence the similar ability to lift the nose i.e. turn when one stab is missing entirely.
Now then, it should also stand to reason that if you try to push the nose down, there should be reduced ability, because of less overall lift that can be generated by the single stab.
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Someone needs to send Big123 to this post, i was missing my left Horizontal Stab in a f4u but was able to almost turn as tight as normal and with the flaps still able to out turn a LA7 and Yak on the deck like it wasn't even missing. He called Shenanigans and i thought it was odd but did notice a bit of loss in lift and more pronounced as i got faster but still able to fight if i had too.
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Im lost, WTF is a force vector displayer. Far out name though.
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Im lost, WTF is a force vector displayer. Far out name though.
It's a program that uses the Aces High physics model to draw vectors (lines/rays of varying length) off the body of the aircraft to show what forces are being applied in what direction to the various parts of the airframe under certain situations.
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Mace I found a USN parts list for the F4u that shows the tailplanes bolted separately to the fuselage with no common spar. In that particular case losing one side shouldn't affect the strength of the other side.
Dirtdart keep in mind that the tailplane is on a lever arm from the center of lift and center of gravity on the main wing. Because it's at the end of the lever and the pivot is at the other end not the middle, the force required for the tailplane to pitch the nose up is not that great. The limiting factor in pitching up is Angle of Attack not elevator force.
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I am wondering... is the removal of weight from the tail of the airplane (or any part of the airplane) factored into the code for how the aircraft performs when the part is shot off?
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Wow, great and very intelligent observations. This has been a fun post. I think I am going to run the math on this. Should be "fun", it has been ages since I had to do any thinking. Anyone have F4U-1a tailplane schematics.....lol. Thanks fellas, fun discussion.
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Anyone have F4U-1a tailplane schematics.....lol. Thanks fellas, fun discussion.
Considering there's a player roaming around here that rebuilds the engines, there must be something. Try the Aircraft and Vehicles forum.
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Wow, great and very intelligent observations. This has been a fun post. I think I am going to run the math on this. Should be "fun", it has been ages since I had to do any thinking. Anyone have F4U-1a tailplane schematics.....lol. Thanks fellas, fun discussion.
(http://www.mediafire.com/imgbnc.php/b9b6aa39c36bd4386fc5df188d7dbe412g.jpg) (http://www.mediafire.com/imageview.php?quickkey=2izni2jtyty&thumb=5)
(http://www.mediafire.com/imgbnc.php/302ca07aa76fc85d01e08ff1efdfaadf2g.jpg) (http://www.mediafire.com/imageview.php?quickkey=ywrmum1nmzw&thumb=5)
This is an F4u-4 not a -1 but I think the construction is similar.
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Keep in mind that in AH the thing is clean gone, but in the real thing you'd have parts of it still bolted onto the frame. It's just that for all intents and purposes it's "blown off"
You'd see a number of planes missing part or most of a single stabilizer in WW2 photos even though it looks like it should never be able to support itself with just 1.
You wouldn't think that something like this could fly and get back, would you?
(http://img1.footnote.com/img/thumbnail/29023941/400/400/0_0_4592_3597.jpg)
It did. Of course, it wasn't pulling 3 Gs in dogfights after that happened, but it happened.
Here're some more:
(http://i.ytimg.com/vi/dQSy4cRd4gk/0.jpg)
(http://northstargallery.com/Aircraft/B17/historical/33.jpg)
(http://i241.photobucket.com/albums/ff37/viking_berserker/B-25FLak.jpg)
(http://www.daveswarbirds.com/b-17/photos/body/b17allamerican.jpg)
(http://www.asisbiz.com/il2/He-111/He-111H-Mixed/images/Heinkel-He-111H-battle-damaged-from-flack-after-a-night-sortie-01.jpg)
I fully recognize that it was rare, that for every 1 that made it back like this, probably 10 never did. I'm not saying AH has it right, as I don't really know my feelings on AH's version of things just yet. I am saying that things like this did happen and the plane didn't fall apart under the stress of a single control, or massive damage. I am definitely FOR having separate damagable h-stabs, and losing 1 without the other. The end flight characteristics are what I'm undecided on so far.
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SOME planes have it where the parts stay there like on the IL2 or the B25H
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yea i'm guessing my damage would have looked more like it does on the planes with the newer damage. something would have been there but not much.
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(http://www.mediafire.com/imgbnc.php/b9b6aa39c36bd4386fc5df188d7dbe412g.jpg) (http://www.mediafire.com/imageview.php?quickkey=2izni2jtyty&thumb=5)
(http://www.mediafire.com/imgbnc.php/302ca07aa76fc85d01e08ff1efdfaadf2g.jpg) (http://www.mediafire.com/imageview.php?quickkey=ywrmum1nmzw&thumb=5)
This is an F4u-4 not a -1 but I think the construction is similar.
:airplane: I am pretty sure you will find a full spar. Without a full spar you would need struts.
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You don't have struts or full spars on many aircraft. Some did, sure, but not all.
Not even the massive stabilizers on the B-17...
(http://www.daveswarbirds.com/b-17/photos/body/b17allamerican.jpg)
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Just to throw some more speculation on the fire, I was flying my F4U-1A last night, which I've had half of the horizontal stab knocked off of before, and it happened again last night.
The interesting thing about last night, based on previous experience I figured I would be maneuvering like a three toed sloth on ludes, so I turned for home directly. Someone with superior E caught up with me, and forced the fight on me. I found my maneuvering capability to be pretty decent. Not fully good, very definitely not better, but not as bad as I'd noticed it in the past when I lost half a stab.
A couple of theories went through my brain. I am not an engineer by any stretch, but logically speaking would it make a difference which side was gone as compared to engine torque? I can't remember which side was gone in my case last night, and I'm wondering if there's some emergent behavior from having one side gone versus the other compared to propeller rotation direction to give it more authority or more volume of air over it, or something along those lines? I'm thinking of the way propwash would 'corkscrew' over the body of the aircraft. Or, maybe just simple engine torque would affect the way the plane was pulling against the lopsided stabilizer when you pull up? If it was on the opposite side, to the way torque wants to pull the aircraft it would seem to me it would give it a touch more authority, wouldn't it?
The other thing that crossed my mind- are there maybe 'slightly' blown off stabilizers and 'very' blown off stabilizers? Kind of like the little oil leaks versus the big oil leaks?
Just thinking out loud. A third possibility is, there was an update in between... Maybe something changed there? :noid
Wiley.
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Man this is what the BBS were meant for IMHO. Great read thx gents. :aok
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Wiley I think that engine torque and torque from the mass of the spinning prop is negligible compared to the torque from the spiral slipstream. You can see the gyroscopic precession from the prop when you push the nose down quickly or pull it up quickly. You'll notice the nose moves slightly to one side or the other. When you reduce torque by pulling power for maneuvering I believe it's the reduced slipstream that you're noticing.
With the spiral slipstream pushing the top of one stab and the bottom of the other I imagine that there would be a slight reduction in the torque on the fuselage regardless of which side was lost.
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Ah, ok. I guess the term 'spiral slipstream' was what I was actually talking about. I was just thinking in terms of it making a difference which side was gone versus which way the prop turns, and all the associated effects that go with it. Learned my thing for the day, thanks! :)
Maybe I wasn't quite clear in my point- I was wondering if the torque/spiral slipstream might make a difference in how much authority half your stabilizer and elevator would have when you pull back on the stick. Basically, if your plane tends to want to roll to the left due to the spiral slipstream, would having the right side of the horizontal stabilizer still attached give you more authority than having the left side of the horizontal stabilizer still attached? Logically, it seems to me it might. And vice versa on an aircraft with the opposite rotation on the prop?
Basically I'm curious why all my previous instances of having half my tail shot off have seemed to me that it was a heckuva lot mushier than it was last night. One other possibility that crossed my mind is airspeed may have played a factor. In previous times I generally was slow and turning and was barely getting any response at all, which is what I'd expect.
Is there a .blowpartoff type dot command that can be used offline for testing?
Wiley.
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I doubt it makes a difference if a stab is pushed up on one side or down on the other. Keep in mind that you're countering the torque with your undamaged ailerons.
I'm not aware of any undocumented dot commands.
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Keep in mind that you're countering the torque with your undamaged ailerons.
If you use Combat Trim, I don't believe it compensates properly for it. That could lead to perceived instability as well.
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Interesting thread.
I have seen many pictures of rear stab damage. Planes making it home with big bits missing. But they have all been bombers. Has any one seen a picture of a fighter getting home with a rear stab missing. The only ones I have seen are of rudder damage.
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I have, but I couldn't find any with a quick google image search when I last replied. Hence the lack of pictures.
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I checked out the drawings, thanks for the post. I guess in reality, without a real aeronautical engineer with the right metal properties, rivet count, design specs, et al, this is just speculation. Someone said earlier, this is what the BBS are about and I agree. Thanks for all who participated.
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Others report being more manuverable than before with 1/2 the stab missing. May be plane dependent.
I don't notice any change in the spit16 when half of the elevator stab is gone. Wait a minute.. this should not be surprising..
:bolt:
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I don't notice any change in the spit16 when half of the elevator stab is gone. Wait a minute.. this should not be surprising..
:bolt:
That's cause the UFO16s don't even need the H-Stabs, HTC puts them on just to disguise them as real planes...
:noid :noid
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(http://www.mediafire.com/imgbnc.php/b9b6aa39c36bd4386fc5df188d7dbe412g.jpg) (http://www.mediafire.com/imageview.php?quickkey=2izni2jtyty&thumb=5)
(http://www.mediafire.com/imgbnc.php/302ca07aa76fc85d01e08ff1efdfaadf2g.jpg) (http://www.mediafire.com/imageview.php?quickkey=ywrmum1nmzw&thumb=5)
This is an F4u-4 not a -1 but I think the construction is similar.
Those are some nice pictures but what you need to understand is that they only show where major components are relative to each other and how they are assembled, not how the structure transmits loads. Yes, the stabs bolt on to the fuselage but what you cannot see is the structural member within the fuselage that they're bolted to. I can guarantee you that the other stab bolts to that same structural member making, from a load perspective what is, in essence, a single spar. What you need to see is the major load carrying members and how and where stress is produced.
It is not at all unusual for individual stabs to be built separately but, from a load perspective, once they are bolted to the major load carrying component of the aft fuselage it becomes essentially a single spar. That major load carrying component may not look like a spar but it carries the load produced by the entire surface. Look at photos of early jets like the F86 and P80. You'll notice that the stabs are mounted at the top of the fuselage. This is to simplify the load carrying structure by mounting it above the tail pipe and it looks kinda like a "knuckle" where the stabs and vertical tail all attach. This "knuckle" is in turn attached to the aircraft's major load bearing longerons forming the monocoque fuselage. On later jets like the F8 and A7 series the stabs are mounted lower making it impossible to use a single spar design or knuckle because it would have to go through the tailpipe. There is; however, a load bearing structure in the tail, it's just built as either a full or partial ring so the tailpipe can go through the center of it but it serves the same function of transmitting lateral loads through the entire tailplane. The same is even true with the F14 where the aft fuselage is actually built up of rings within each engine nacelle that the stabs (and vertical tails) attach to but then those nacelle rings are joined by a structural member through the flat area between the afterburner cans (called the boat tail). Again, making a continuous load-bearing structure. In the more modern cases, the aircraft use what are called "differential tails". In these designs the horizontal tail surfaces are intended to produce roll by deflecting in opposite directions and intentionally producing large torque moments in the aft fuselage but since they are designed specifically for this type of stress the structures are stronger than non-differential tail designs.
In the pictures where aircraft have landed with a stab missing one of three conditions must have occurred. Either they were unable to generate normal maximum loads with just a single stab (meaning reduced control power and turning capability and resulting torque), the pilot was not in a situation where he needed maximum control power for the maneuvers he needed (which again means less that normal maximum turning capability and low torque), or reduced stability reduced the control power (and torque) required to generate the required pitch. This third condition (as suggested by HiTech) is that the reduction in longitudinal static stability results in a lower control power requirement for the required pitching moment. Now you'd have to look at how much longitudinal stability is reduced by the loss of the stab. Is it still positive, neutral, or negative? If it's still positive, then the reduced control power may be able to generate the pitching moment needed but the pilot is definently going to know something major is wrong because he can feel the instability. If neutral, the pilot would really begin to have real problems controlling the plane and if negative, all his attention would be focused on simply keeping the plane flying (and he would probably fail). In all these cases the pilot would more likely be more concerned with maintaining control rather than making high performance turns.
It is counter-intuitive (and highly unlikely) that the loss of stability combined with reduced control power requirements would balance out to the point that the airplane flies more or less normally. My contention is that it is unlikely that an aircraft missing one stab will be able to maintain anywhere near it's normal maximum turn rates either because of insufficient control power, failure of the remaining stab and/or fuselage due to stresses it was not designed to handle or flat out instability. In none of these cases would the plane fly as if it still had both stabs.
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I think Hitech's point that "turn performance would degrade or possibly remain the same" implies that the elevator normally has more authority than it needs. I don't think anyone said it would fly normally. I thought we were talking about flying better than intuitively expected.
If the stab attachment is built into the fuselage in some manner and has the effect of a continuous spar then it's not a continuous spar but I don't think it's worth quibbling over definitions. I assumed that the attachment points pictured were part of a fuselage structure that was designed for more than the anticipated normal range of loads. I will happily call it a continuous spar for this discussion. I just don't see where it makes a difference since the individually attached stab is designed for the forces applied to it. You haven't shown where the attachment requires balanced forces on both sides in order to maintain structural integrity which I believe is the point in contention.
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I think Hitech's point that "turn performance would degrade or possibly remain the same" implies that the elevator normally has more authority than it needs. I don't think anyone said it would fly normally. I thought we were talking about flying better than intuitively expected.
There have plenty of comments from folks that the aircraft missing a stab turns as well or better, that's what pretty much started this thread. That just shouldn't happen because of structural loads or instability. If it were true, why add all the extra weight and complexity of that "redundant" stab??? Just leave it off and you're good to go with a lighter and less complex airplane! :D
If the stab attachment is built into the fuselage in some manner and has the effect of a continuous spar then it's not a continuous spar but I don't think it's worth quibbling over definitions.
I didn't say it was a continuous spar, I said it acted like one and qualified my comments with "in essence" and "essentially". This is really, really basic mechanics for levers here so I'll try one more time. With a complete horizontal stab generating approximately equal lift from tip to tip the resulting stress at the fuselage junction is in essentially a straight line normal (i.e., 90deg) to the spar. With a single stab the type of stress is completely different, it's not a straight line, it's a twist. Maybe this example will make sense. Glue a block of wood to a wood deck and try to pull the block straight up with all your strength (say 200lbs). With good wood glue this would be very difficult or even impossible to do. That is a "normal" load, in other words it's 90deg to the joint and in the direction of the joint's maximum strength and can easily handle that 200lb pull. That's the type of stress created by a complete stab. Torque is a completely different type of stress. Attach one end of a horizontal 2x4 (a hypothetical single "stab") to the block and pull up on the other end of the 2x4 with the same 200lbs you used previously. The resulting torque will probably easily twist the joint apart. This demonstrates that the uneven leverage (or torque) is much more capable of separating the joint than a straight pull so it's not just the load that matters but how it's applied. If this still doesn't make sense then you'll just have to trust me and yes, my degree is in engineering.
I assumed that the attachment points pictured were part of a fuselage structure that was designed for more than the anticipated normal range of loads. I will happily call it a continuous spar for this discussion. I just don't see where it makes a difference since the individually attached stab is designed for the forces applied to it.
It has nothing to do with the stab itself, it has everything to do with the fact that the stress applied to the fuselage juncture with a single stab is pure torque, not the normal "forces applied to it" that the aircraft designer intended.
You haven't shown where the attachment requires balanced forces on both sides in order to maintain structural integrity which I believe is the point in contention.
I didn't say it required balanced forces or that it would automatically come apart, I'm saying that it's unlikely that sufficient structural margin exists to handle very high torque stresses that were never intended to be applied. I've personally seen the tips of F14 horizontal stabs bend downward (as the wingtips bend up) while generating maximum pitch rates. That's a lot of load on those suckers and I wouldn't want to see what happened if I generated the same load with a single stab.
Aircraft design is really a balancing act. Make things too weak and they break, make things too strong and the airplane gets too heavy. All aircraft are "overdesigned" to a degree to provide a safety margin and that margin is specified in contracts and MILSPEC. For instance an aircraft with a +6G limit will not fall apart at +6.1G but it will begin to have permanent deformation and/or structural failure at some point. Take the +6.0g wing and push it to -6.0G and it probably will fail as that's not the load it's designed to handle. As I mentioned previously, the F14 was specifically designed to handle the torque produced by differential tails, that's what makes it roll (well that and spoilers). Even so, when they added new computers for the stability augmentation system and tested its improved roll capability the test aircraft was severely overstressed and damaged by the torque. Basically what happened is the increased torque produced by the differential tails with the new computers exceeded the safety margin and almost twisted the back end of the airplane off of the front end.
Still, much of this argument may be moot given HiTech's comments about loads being reduced by reduced static stability but it's an interesting discussion anyway. I still contend that the airplane will not fly anywhere near "normal" as some people here have claimed and you certainly wouldn't be able to continue to fight with half your stab missing.
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I agree with just about everything you're saying Mace, just not your conclusion.
Anecdotal evidence from players isn't convincing and hasn't contradicted Hitech's comment.
Maybe the "extra" stab is redundant in case you lose one. :neener:
When I said "has the effect" I'm agreeing with your "in essence" and "essentially". I got the teeter totter example the first time. I try to avoid arguing with engineers because they cheat and use "math". :D I understand your example, but you haven't convinced me that it applies in this case. Might apply? Certainly. I don't pretend to know differently, but I find it easy to believe that the extra stresses could be handled by mid-war aircraft design. As you noted fighter aircraft designers anticipate combat damage and design for it when they can. Isn't that why Grumman was called the "iron works"? I know we're not just talking about Grumman here but as you know it's their bird in the drawings.
Maybe we'll see changes with the expanded damage model. It could be that finding a point where a single stab would fail has the same difficulties as determining when a flap would fail if left down at too high a speed. It could also be that Hitech has modeled the stress and it's not as great as it might seem.
I don't recall ever losing just one stab in AH so I don't know first hand how it flies afterwards. I do appreciate your attempts to educate me. :cheers:
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I agree with just about everything you're saying Mace, just not your conclusion.
Anecdotal evidence from players isn't convincing and hasn't contradicted Hitech's comment.
Maybe the "extra" stab is redundant in case you lose one. :neener:
When I said "has the effect" I'm agreeing with your "in essence" and "essentially". I got the teeter totter example the first time. I try to avoid arguing with engineers because they cheat and use "math". :D I understand your example, but you haven't convinced me that it applies in this case. Might apply? Certainly. I don't pretend to know differently, but I find it easy to believe that the extra stresses could be handled by mid-war aircraft design. As you noted fighter aircraft designers anticipate combat damage and design for it when they can. Isn't that why Grumman was called the "iron works"? I know we're not just talking about Grumman here but as you know it's their bird in the drawings.
Maybe we'll see changes with the expanded damage model. It could be that finding a point where a single stab would fail has the same difficulties as determining when a flap would fail if left down at too high a speed. It could also be that Hitech has modeled the stress and it's not as great as it might seem.
I don't recall ever losing just one stab in AH so I don't know first hand how it flies afterwards. I do appreciate your attempts to educate me. :cheers:
I agree partly with what your saying but, it's not a Grumman in the picture, I could be wrong but I doubt it, didn't Vought make the Corsair's?
Pretty sure they did, but I could be wrong. :rolleyes:
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You're right it's Chance-Vought, I tend to think of the Corsair and Hellcat as similar and confused the manufacturer even though I know better. :headscratch:
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Well, I also am an Engineer, just not an aero guy. This seems on the unlikely side. Me fighting a N1K1 with no outer left wing (aileron) and no left stab at all. Still rolled left and right. Could the rudder change the AOA on the left wing enough? Don't know.
(http://hphotos-sjc1.fbcdn.net/hs434.snc3/24973_385038252948_700532948_3992997_2954809_n.jpg)
(http://sphotos.ak.fbcdn.net/hphotos-ak-ash1/hs454.ash1/24973_385038247948_700532948_3992996_6172817_n.jpg)
To actually fly, even somewhat level with say 40-60% of your lift on the port side gone...bah. Then the guy dropped his gear and the nearly landed, crashed into a tree.
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You only need one aileron to roll. You can also roll with the rudder. Cruising speed is not too difficult with part of one wing missing but when you slow down you tend to roll towards the broken wing. Flaps help.
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The use of aileron in this instance would reduce the lift on the right wing, which makes the nose drop. Curious. I would love to see a fluid shot of shot up plane like this and see the lift drag and stresses.
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Why not just increase AOA to compensate? You'd be using aileron, elevator and rudder all together in any case.
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I've noticed that on some planes the h-stab is above the point at which the fuselage connects to the v-stab and rather the h-stab goes through the v-stab. On these planes, if you shoot off the v-stab, the h-stab some how stays connected even though its floating above the fuselage. Also, I'd imagine that removing half of the h-stab would put so much uneven force on the v-stab, that it would bend or break it off.
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Any input you make has a consequence. If I input aileron to compensate for loss of wing, nose drops. I input elevator to raise nose and increase AOA, I decrease speed and lift. I think what is in order here is some posts of "most shot up planes you have ever seen still flying", but that is indeed a new thread!
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Nevermind, didn't read past page 1 before posting.
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I think we all need to agree to disagree because this is just a rehash of the same argument over and over. Didn't HiTech answer this already with his force modeler?