Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: PJ_Godzilla on October 06, 2009, 11:30:59 AM
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I've heard numerous anecdotes of the use of rear-view mirrors on WWII A/C canopies. The last one I heard talking of this was Gunther Rall. It was on a "Clash of Wings" (Military channel) interview. He was recounting getting shot down - and losing a thumb - by a P-47. Prior to that tale, he referred to the fact that he'd put mirrors on his 109 canopy. He said it was difficult to see much through them because they'd vibrate badly. He said, and I paraphrase, "if you could see anything in that mirror, it was time to bail out."
We have no mirrors in AHII. Why? They were a fairly common upfit.
Here's an example from a Typh: http://www.wwiiaircraftperformance.org/typhoon/typhoontest.html
If you can't see it, search for the word mirror.
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We have no mirrors in AHII. Why? They were a fairly common upfit.
Did you try to use the "search" button? Has been discussed lots of times. ;)
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That's alot of work for the end user..............
If you can't see it, search for the word mirror.
But.... What Lusche said...... :aok
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Question:
We have no mirrors in AHII. Why? They were a fairly common upfit.
Answer:
...he'd put mirrors on his 109 canopy. He said it was difficult to see much through them because they'd vibrate badly.
So, you want HTC to add properly-modelled mirrors? You might as well just add a rectangle filled with a static image of gibberish. Then you'd have what they had. ;)
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Good answers - yes, I should've searched, just to see what has gone before.
Here's the thing, though. Last time I searched up a topic on a couple of turn radius and rate questions I had, I came across a thread that touched on both as well as the topic of max bank angle. I did some development on the ideas using some common aero formulas and some reasoning.
Skuzzy then wiped out the whole thing and hit me with a "punting" violation. According to him, since Simaril no longer posts here and the thread was a few years old, I was clearly engaged in an attempt to bring an outdated post back to the top of the list.
I understand why he hit me with the violation. I wonder if he understands the uninrtended consequence of it. You can search, true, but any follow-ups better be via a new thread - at which point you have to waste a bunch of time reframing the context - it's so much easier just to start a new thread on the same old crap. My own recommendation would be, if the post is substantive, so what if the issue gets punted up to the top of the queue? Obvious punts are another matter - posts of little/no substance intended to promote an item to the top of the queue should be snuffed out.
There. I've now hijacked my own thread. Perhaps I can draw a violation flag.
As for rectangles of gibberish, there are informative rectangles of gibberish and less useful forms of the same... That, and I doubt the vibration was anything like constant - though here the pain in th a** factor begins to play. After all, the thing will have some set of resonant freq dependent on the mount and will be excited by either large amplitude forces off-resonance or smaller ones on-resonance. Perhaps a "standard mount" might be developed across the board..? My suspicion: at the right engine rpm and aero loads, the thing was probably fairly well settled - other times, a mere blur. Figure a rigid mount to the canopy structure and it would just slightly mass-damp the canopy frame, right?
Agreed, though... probably not worth the (major) hassle...
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Use search for reading only.... never post
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Use search for reading only.... never post
And then you can start a new thread referencing the old thread and not get the "have you tried searching?" response.
Anyway, the real reason there are no mirrors, besides stated above, is a performance issue. Not only would your computer need to render the "big" view, it would also have to separately render the video seen in the mirror.
Frame rate killer.
wrongway
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As for rectangles of gibberish, there are informative rectangles of gibberish and less useful forms of the same... That, and I doubt the vibration was anything like constant - though here the pain in th a** factor begins to play. After all, the thing will have some set of resonant freq dependent on the mount and will be excited by either large amplitude forces off-resonance or smaller ones on-resonance. Perhaps a "standard mount" might be developed across the board..? My suspicion: at the right engine rpm and aero loads, the thing was probably fairly well settled - other times, a mere blur. Figure a rigid mount to the canopy structure and it would just slightly mass-damp the canopy frame, right?
Agreed, though... probably not worth the (major) hassle...
Man, I'm digging through my back-log of waves knowledge now... makes me wish I still had my book.
From what I remember, can't you use a huge impedance mismatched material as the mount? I.e., since
we are given the metal frame and glass mirror, we can pick a material to mount the mirror in such that its natural impedance will be very different from that of either the frame, the mirror, or both. This would reduce its transmission coefficient.
Raises an interesting question: how historical are the solutions we propose to the mirror problem?
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Basically, with AH's viewing system, mirrors would give you *nothing* you don't already have, but would greatly increase the graphics load.
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Man, I'm digging through my back-log of waves knowledge now... makes me wish I still had my book.
From what I remember, can't you use a huge impedance mismatched material as the mount? I.e., since
we are given the metal frame and glass mirror, we can pick a material to mount the mirror in such that its natural impedance will be very different from that of either the frame, the mirror, or both. This would reduce its transmission coefficient.
Raises an interesting question: how historical are the solutions we propose to the mirror problem?
Sure - sounds like classic isolation. I'm going to go hunt around, if I get a few minutes (what are the odds?) and see if I can find more testimony. I seem to recall some British pilots who made good use of the mirror on their Spits.
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Basically, with AH's viewing system, mirrors would give you *nothing* you don't already have, but would greatly increase the graphics load.
You could do a cursory check on your six without having to take your focus off your target.
Also, if we implement a non-vibrating mirror, it shouldn't increase graphics load that much. The mirror provides only a thin slice of the overall rear view after all.
It would not increase graphics load beyond having an additional section of sky in the forward view - therefore the additional load would at maximum be equivalent to having no cockpit in the forward view. The calculation for what to show in the mirror based on headposition should be negligible compared to the overall graphics load in the first place.
In addition, AH's graphics are highly scaleable anyways. Note that sims as old Jane's USNF implemented a rear view mirror.
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You could do a cursory check on your six without having to take your focus off your target.
Also, if we implement a non-vibrating mirror, it shouldn't increase graphics load that much. The mirror provides only a thin slice of the overall rear view after all.
It would not increase graphics load beyond having an additional section of sky in the forward view - therefore the additional load would at maximum be equivalent to having no cockpit in the forward view. The calculation for what to show in the mirror based on headposition should be negligible compared to the overall graphics load in the first place.
In addition, AH's graphics are highly scaleable anyways. Note that sims as old Jane's USNF implemented a rear view mirror.
In IL2 at normal zooms, the only thing the mirror tells you is that there is an enemy icon somewhere on a LOS with the mirror. Flicking your direct rear view in AHII tells you much more, and doesn't require taking your eye off the target for more than a split second with snap views. Redundant.
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Time to bail out?
(http://ripplingerfamily.us/funnies/RearViewMirror.jpg)
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In IL2 at normal zooms, the only thing the mirror tells you is that there is an enemy icon somewhere on a LOS with the mirror. Flicking your direct rear view in AHII tells you much more, and doesn't require taking your eye off the target for more than a split second with snap views. Redundant.
Except the mirror gives you continuous monitoring of a small slice of your 6. Also, that split second can still be quite significant - what if you get a Check6 call while you are moments away from a shot opportunity? Do you snap view over and risk losing the shot or do you take the shot and risk losing your plane? The mirror removes having to make this decision for a small slice of your rear view.
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One thing with Il-2 is that it some aircraft had better coverage on their mirrors than the game provides.
IE: The bubble-top F4Us had THREE mirrors on the canopy frame: one on each side and one above. Il-2 only provides the center one, which does restrict the available coverage.
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Mirrors can be misleading...
(http://www.reallyfunnystuff.org/wp-content/uploads/2009/05/mirror1-450x460-custom.jpg)
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According to a Spitfire pilot from the Battle of Britain, a Bf109E in firing range was about the width of a - in the mirror. He said it was useless. In AH that - would be more like a . when it was in firing range.
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According to a Spitfire pilot from the Battle of Britain, a Bf109E in firing range was about the width of a - in the mirror. He said it was useless. In AH that - would be more like a . when it was in firing range.
Wouldn't that be due to how much magnification the mirror provides? Seems to me as this is a tradeoff as with ANY FoV zoom.
More zoom => better detail, but less spatial area covered. Less zoom => less detail, but bigger area covered. So it sounds like the Spit mirrors simply chose the low zoom/low detail method. I guess this is an additional area we'd have to look into and/or adjust when picking mirrors.
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Wouldn't that be due to how much magnification the mirror provides? Seems to me as this is a tradeoff as with ANY FoV zoom.
More zoom => better detail, but less spatial area covered. Less zoom => less detail, but bigger area covered. So it sounds like the Spit mirrors simply chose the low zoom/low detail method. I guess this is an additional area we'd have to look into and/or adjust when picking mirrors.
The more you "zoom" the less the field of view and the lower the odds of the attacking aircraft appearing in the mirror.
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The more you "zoom" the less the field of view and the lower the odds of the attacking aircraft appearing in the mirror.
Yes, exactly. The tradeoff is it's harder to actually see the attacking plane when you are zoomed out (i.e., your comment on how the 109s looked like a -).
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I would like to see the mirror atleast as an option for my plane.
Maybe this post should go in the wishlist forum.
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Yes, exactly. The tradeoff is it's harder to actually see the attacking plane when you are zoomed out (i.e., your comment on how the 109s looked like a -).
Even better would be if you could choose the zoom. It'd be yet another tactical tradeoff the user could make.
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Even better would be if you could choose the zoom. It'd be yet another tactical tradeoff the user could make.
This is exactly how I envision the mirror system working.
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All this mirror talk reminds me of a story.
A man was sealed in a room with no doors or windows. All he had was a table with a mirror on it. He was actually able to escape when he looked into the mirror to see what he saw.... took the saw and cut the table in half. Put the two halves together to make a (w)hole and he was able to climb right through it.
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This is exactly how I envision the mirror system working.
Uh-oh... I sense a techno-geek with a resonant view to my own. This could lead to a discussion that outsiders would entitle "Boron versus Drone-O" in which two techno-geeks attempt to impress the rest of the world with their talent for ending insomnia.
BTW, with regard to that "other topic", I'll just say that it's clear from the log that many in the log needed a little more explanation and that takes time and pixels. It's still a sound clientele and a bunch of pretty good guys, mostly pretty sharp if not necessarily trained in the specific bookwork - and many of the better flyers probably aren't (and I'm not one of 'em).
Speaking of which and at the threat of hijacking the thread: there are no women here. I don't care. I'm married. I go here to get away from the henhouse. For some of the other guys - especially the young 'uns, though, spending a lot of time on AHII might be something akin to enrolling in the monastery.
Ah, well, they can go to the bars and brag about their kills. That should impress 'em. Wait 'til I'm retirement age. My pilot skills will go through the roof.
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Do a search, HT already said it's not worth the trouble of coding it. The hit on graphics for such a small and quick view just isn't worth it.
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Uh-oh... I sense a techno-geek with a resonant view to my own. This could lead to a discussion that outsiders would entitle "Boron versus Drone-O" in which two techno-geeks attempt to impress the rest of the world with their talent for ending insomnia.
:rofl. Check out The Big Bang Theory (TV Show) some time.
BTW, with regard to that "other topic", I'll just say that it's clear from the log that many in the log needed a little more explanation and that takes time and pixels. It's still a sound clientele and a bunch of pretty good guys, mostly pretty sharp if not necessarily trained in the specific bookwork - and many of the better flyers probably aren't (and I'm not one of 'em).
I take it this is about my PM to you? What I'm saying is, it seemed like the only important issue is where CL of the wings lies. Take out the elevators and then only the wings generate lift. And if CL is in front of CG, nose will pitch up (all fulcrum-like), which is a pretty basic principle. The issue could be very easily boiled down to one paragraph if everybody knew that CL of the wings was in front of CG and it would be pretty intuitive to boot by simply describing a basic fulcrum.
The discussion could have been cut much shorter if Hitech (or anybody else with expert knowledge) had stated the CL of the wings early. I wasn't trying to say anything else by my PM, certainly not trying to criticize anybody's lack of knowledge or God forbid pilot skill.
Speaking of which and at the threat of hijacking the thread: there are no women here. I don't care. I'm married. I go here to get away from the henhouse. For some of the other guys - especially the young 'uns, though, spending a lot of time on AHII might be something akin to enrolling in the monastery.
Ok, I'm starting to the impression that we are talking about completely different things now. I'm confused. Oh well.
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:rofl. Check out The Big Bang Theory (TV Show) some time.
I take it this is about my PM to you? What I'm saying is, it seemed like the only important issue is where CL of the wings lies. Take out the elevators and then only the wings generate lift. And if CL is in front of CG, nose will pitch up (all fulcrum-like), which is a pretty basic principle. The issue could be very easily boiled down to one paragraph if everybody knew that CL of the wings was in front of CG and it would be pretty intuitive to boot by simply describing a basic fulcrum.
The discussion could have been cut much shorter if Hitech (or anybody else with expert knowledge) had stated the CL of the wings early. I wasn't trying to say anything else by my PM, certainly not trying to criticize anybody's lack of knowledge or God forbid pilot skill.
Ok, I'm starting to the impression that we are talking about completely different things now. I'm confused. Oh well.
I was just digressing at the end there because I'd referred to a "pretty good bunch of GUYS". Then I realized, there are no women here.I once tatered a Mossie driver with the "Pink Leather Aces" squad but my guess is, that was a he. What's up with that squad name, anyway?
Otherwise, I mistook your point on the center of lift. Generally, the entire ac center of lift is aft of the cg, that latter generally balanced at about quarter chord, statically. Indeed and as you state, blow the tail off and it moves to roughly wing c of l. But it was clear that a couple of the contributors didn't know how to do even a force balance - consider some of the murk around whether the horistab was producing negative or positive lift.
The other distraction there: I don't know about you but, for me, it was the first time thinking about what happens to the a/c when you blow a big chunk off it. It took us all a while to get there. In retrospect, it seems dead simple. We could repeat this thought experiment with a number of other scenarios. I think we've already covered the half-a-wing one side or both scenario. What about the vertstab? It's far less common an occurrence.
yer pal,
Boron
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I've talked to two women in AH so far. One's Fiona and the other's deafchick. On top of that, I've also heard of Barbie, who flies with Loose Deuce. Pink Leather Aces hahaha, never heard of them.
Yup, we have quite the sausage fest here. My university was this way too, though not nearly as bad.
Re: CL discussion. Force balance or not, all we have to say is that CG is the "fulcrum point" - if we're pushing up at CG, the aircraft will not pitch up or down. This can be demonstrated with examples among household objects - when you balance anything on your fingertip, you are matching the CG along the horizontal. While holding the object balanced, push up to see what CL does. Very simple example, very intuitive, and close to how I imagine complex problems in my head. I once explained resonance frequency to a friend by using a swing set as an example.
Drone-o
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We could repeat this thought experiment with a number of other scenarios. I think we've already covered the half-a-wing one side or both scenario. What about the vertstab? It's far less common an occurrence.
I routinely get my VStab blown off! :lol. Well in that case, we would be forced to use ailerons to counteract engine torque. But since ailerons naturally produce some yaw rate, the aircraft would rapidly acquire a large horizontal AoA. This is assuming the aircraft is geometrically symmetric along the plane defined by the VStab. If not, any asymmetries would be enhanced and would probably also contribute to the yaw. The result: a flat spin, with some rolling motion due to torque. I think that agrees pretty well with combat experience in AH.
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I routinely get my VStab blown off! :lol. Well in that case, we would be forced to use ailerons to counteract engine torque. But since ailerons naturally produce some yaw rate, the aircraft would rapidly acquire a large horizontal AoA. This is assuming the aircraft is geometrically symmetric along the plane defined by the VStab. If not, any asymmetries would be enhanced and would probably also contribute to the yaw. The result: a flat spin, with some rolling motion due to torque. I think that agrees pretty well with combat experience in AH.
I agree. However, my recollection of aircraft performance said there is a significant stability drivative that we dubbed "the weathervane effect". It effectively minimizes your sideslip. While the vertstab is doubtless a big contributor to that effect, I am also very sure that on a/c of the type we fly, the aft fuselage is also a significant contributor.
I just wonder if, given some trace of d(Yaw moment, call it Z)/d(yaw angle, call it phi) and the fact that at some phi we'd have a yaw contribution from that effect that was proportional to that coeff and to the square of velocity that the flat spin you posit might be a major issue at low speed but much, much less of a problem if we've got a little smash-ola? It's hard to say because the induced drag diff due to ailerons left to right will also be higher.
I'd further posit that a relatively slab-sided bird like the 51 would have a steeper slope/higher Cz w/r phi at all phi than something with a rounder/narrower rear fuselage like a d-9.
I was also considering the case where we're sharply banked at the time of the separation event. This looks like a decent analog to out horistab discusion only there's less possible lift forward - just the fuselage contribution and whatever vertical component the wings are producing. Clearly here, we'd be negative cambered on the vertstab to try to keep the nose up and at a very high Cl ergo alpha on the wings to attempt to keep from losing lots of alt. Blow the vertstab off and do we now also yaw nose up? I think it likely - especially given the attenuated nose-down pitch moment of the wings in that plane (horizontal w/r ground).
One other thought - with the canard, if we blow the horistab off it seems to me the center of lift would shift further aft. That looks like it might pitch nose down - a safer failure mode.
Anyway, that's my thought on this "Mirrors" issue. Best to keep 'em on the airplane because strange things can happen when they get shot off.
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Mirrors? Yes, I'm tired of hanging my pine tree air freshener and fuzzy dice on my monitor :cheers:
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Mirrors?
I rarely look at the gauges, let alone mirrors.... and don't even bring up that you can use flaps too
:banana:
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Heh, sign up for a game, get part of an aero education.
Right, I would expect the fuselage to act as one big stabilizer. Not sure how much it would help with the VStab loss though. At least with AH physics, it doesn't help very much, even at high speeds.
As far as what happens with a banked turn and the VStab gets blown off? That seems a bit beyond me and my simple examples :huh. But, from AH experience:
In a turn, the aircraft will naturally have some sideslip, i.e. yaw AoA with nose higher than velocity vector. If you are applying top rudder, this will only enhance the yaw AoA. With all this, it seems that the rudder is opposing gravity's tendency to bring the nose down. Shoot of the VStab and shouldn't gravity bring the nose downwards?
Canards: yeah, that seems right to me. Why is nose down a safer attitude though? I haven't ever thought about bailing out of a real aircraft that has lost its HStabs after all.
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Heh, sign up for a game, get part of an aero education.
Right, I would expect the fuselage to act as one big stabilizer. Not sure how much it would help with the VStab loss though. At least with AH physics, it doesn't help very much, even at high speeds.
As far as what happens with a banked turn and the VStab gets blown off? That seems a bit beyond me and my simple examples :huh. But, from AH experience:
In a turn, the aircraft will naturally have some sideslip, i.e. yaw AoA with nose higher than velocity vector. If you are applying top rudder, this will only enhance the yaw AoA. With all this, it seems that the rudder is opposing gravity's tendency to bring the nose down. Shoot of the VStab and shouldn't gravity bring the nose downwards
Canards: yeah, that seems right to me. Why is nose down a safer attitude though? I haven't ever thought about bailing out of a real aircraft that has lost its HStabs after all.
On the banked example, sure, but you could say that about the horizontal case as well, right? It all depends on where the CG is relative to the wing lift vector. That will also determine whether the horistab or vertstab, in the case we're talking about, is unloaded or lifting positively or negatively.
As posited, though, yes, I agree with you. Usually, I have to hold the nose up by deflecting rudder to put the tail down in a bank. This is a little counterintuitive to me, though, given HTC's talk on how the CG is usually aft of the forward center of lift on AHII a/c.
I'd say nose-down is a better failure because you won't stall. Because of that, you'll retain some airflow and controllability. Consider dreamchild's assertion that he can turn level by using flaps in his FM2 - even sans tail. I'd expect some limited pitch control with flaps in the canard, provided some airflow over the wings.