Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Blue Mako on September 06, 2001, 11:11:00 PM
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Does anyone out there have a list of corner velocities, max sustained turn rates, turn radii, etc. for the AH plane set?
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<el punto>
Anyone? Any plane?
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Originally posted by Blue Mako:
<el punto>
Anyone? Any plane?
punto in Spanish is point or period, bud...
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I think there isn't much of those data because literally, "turn rate" is an extremely difficult concept to define. What in the world is a "Turn Rate"?
There's a 'turn angle', which determines how sharp an angle a plane can turn while in its usual combat speed..
Then there's 'turning speed'.. whether or not the plane can maintain effective speed while turning.
The 'turn maintenance', a plane might not be able to turn sharp angles, but due to superior engine power, it may maintain good turning speed for quite some time.
I remember once when I was out turned by a Typhoon in a 109G2 at deck. The Typhie had a bit of speed and so did I. I got careless and just tried to lead turn into the Typhie. Seeing that the Typhie kept on turning instead of escaping, and I am very very close to getting a shooting angle, I just lowered throttle, put out flaps and kept on turning. We went in circles like 8~9 times, and to my surprise, I was out turned. I was really close to getting an angle, but I began top stall out. And the Typhie landed behind my 6, in the final phase..
All that above combined is I think what we call "Turn rate" or "Turning power".. and even if we sum it all up, the turning rate of a plane still changes dynamically and relatively depending on many situations and elements in combat. A P-47 can actually turn with 109G2 or G6s at 27~28k alt. :) Initial speed alters turn rate, and roll rates also effect the turn rate in scissors combat.
Therefore, 'turn rate' is not quite a pre-determined element of an airplane. Maximum speed, climbing rate, roll rate.. etc etc.. these are pre-determined elements of an airplane which can be charted out in graphs, but "turning rate" can is not.
Rather, 'turn rate' is more of a situation than pre-determined aircraft ability. Therefore, in essence, turn fighting is essentially same with Boom and Zooming. Turn fighting and Boom Zooming is both management of E, the former in the horizontal sense, and the latter in the vertical sense. Of these two, we naturally choose the latter since it is more effective. But turn fighting also needs effective E management - and these sort of management always comes in more important than the 'turn rate'.
OOps.. :D Sorry for the lecture.. me and my big mouth.. I could have just said "I don't think I've seen any data of that sort".
:) cheers
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Originally posted by Kweassa:
...I could have just said "I don't think I've seen any data of that sort".
Yup (check my profile :) ). Just wondering if there are any charts or figures that people have compiled or HTC have released.
Thanks for your post anyway...
ispar: What is the Spanish word for punt then? (not that I was even trying to write Spanish anyway ;) )
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Hi Kweassa,
>I think there isn't much of those data because literally, "turn rate" is an extremely difficult concept to define.
"Turn rate" is angular velocity, the rate at which the aircraft turns (for example in degrees per second). Of course, your lecture applies perfectly - turn rate depends on many parameters!
Accordingly, turn rates are usually provided only for a specific situation: The flat circle "sustained" turn. It's sustained because it uses energy at the same rate it's provided by the engine.
(The Soviets in WW2 actually relied on the reciprocal value - the "circle time" in seconds - as a measurement of an aircraft's manoeuvrability.)
The other interesting turn rate would be the corner ("instantaneous") turn - the greatest turn rate regardless of energy loss -, but since you can't keep it up, the actual turn rate isn't of great interest - it's better to know the corner speed and just pull back on the stick when the moment arrives!
Knowing the sustained turn capabilities will help you to know whether you might win or lose once the fight got low and slow - but since it varies quite a bit with aircraft weight, you couldn't be sure without trying ;-)
Regards,
Henning (HoHun)
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Originally posted by Blue Mako:
Does anyone out there have a list of corner velocities, max sustained turn rates, turn radii, etc. for the AH plane set?
First of all, try this link:
http://www.simhq.com/simhq3/sims/air_combat/energymgmt/index-pf.html (http://www.simhq.com/simhq3/sims/air_combat/energymgmt/index-pf.html)
Unfortunately, Badboy doesn't provide any details on how he calculates those diagrams. Since I was curious about the rest of the planes in AH (used to play AW so a lot of the planes here are new to me) I did some thinking and came up with a method of my own.
The whole procedure can be done offline, takes 10-15 minutes per plane, and requires no particular flying skill.
1. Go offline, set fuelburnrate to 0.001
2. Select a plane, note armament, fuel etc.
3. Get to desired alt, engage autopilot.
4. Adjust throttle until speed reaches target speed
5. Start film, wait 3 seconds.
6. Pull all the way back on the stick for a few seconds. The aoa will increase and with it the G-force (lift) until the plane reaches a stall or a blackout. When this happens, wait a couple of seconds and then stop film. 7. Repeat from 3, but at another target speed
After these steps have been repeated for a number of speeds (I usually test for all "ticks" on the airspeed indicator between stall speed and top speed), go into the film viewer and look at each film in slow motion. Note the speed and the maximum G in each film (zoom in on the dials if needed). This gives a table something like this:
La5, 25%fuel, 1k alt
IAS MaxG
125 1.5
150 2
175 2.7
200 3.3
225 4.2
250 5.5
275 6.7
300 8.1
325 8.6
340 8.9 Top speed
350 8.9 Top speed with WEP
How to turn max G into turn rate? I align the acceleration vector so that its projection in the vertical plane equals 1G, and calculate
the projection onto the horizontal plane, which is then equal to a = (maxG^2-1)^0.5. Basic physics for circular motion tells me that the angular velocity (= instantaneous turn rate) w is: w = 1258*a/v, w in deg/s, a in Gs, v in mph. I can then add another column into my table:
IAS MaxG Turn rate
125 1.5 11.3
150 2 14.5
175 2.7 18.0
200 3.3 19.8
225 4.2 22.8
250 5.5 27.2
275 6.7 30.3
300 8.1 33.7
325 8.6 33.1
340 8.9 32.7
350 8.9 31.8
This can then be plotted in a diagram. (I would have showed you what it looks like if I could figure out how to put an image here...) Basically you can read the corner speed and turn radius from the diagram.
Getting the sustained turn rate requires some additional information. I have an idea for how to get this also but haven't tried it yet.
Before I do that I would appreciate some feedback on my method. Hopefully there are lots of knowing people who can tell me if I am on the right track?
/haa
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Originally posted by Blue Mako:
ispar: What is the Spanish word for punt then? (not that I was even trying to write Spanish anyway ;) )
Allow me ispar :)
Literally, it would be "patada" (as in kick), but in this context I would use "recordatorio" (as in reminder).
BTW, punto also means "knitwear" :)
Daniel, aka Cyrano
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No sustained turn data that I know of, but the best general performance data I've seen for the AH planes is at http://www.netaces.org/home.html#title (http://www.netaces.org/home.html#title) .
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Originally posted by Blue Mako:
Does anyone out there have a list of corner velocities, max sustained turn rates, turn radii, etc. for the AH plane set?
I don't think a complete exposition exists at the moment, but it is planned. I'm currently in the process of completing a writing project for a jet sim and as soon as that is done I'll start work on a set of diagrams like this one that contains all of the information you mentioned and much more:
(http://www.netcomuk.co.uk/~badboy/PDF/AH-P-51vsP-38.jpg)
I hope to do that for all of the aircraft in AH, They will be made available on the AH web site.
I'm not sure what order I'll do them in, I'll probably do what I think are interesting or historical match ups and build articles around them to make the presentation more helpful.
Also, I think I'd really like to do an AH strategy guide. That would be a good way to present the most in depth performance analysis for the aircraft in AH and cover all the relevant BFM/ACM at the same time. I'm looking forward to doing something like that even more because I believe there is a very good way to teach BFM to sim pilots that doesn't appear to have been published before. I just need to persuade my partner (Andy Bush) and a publisher that its worth doing and it might get off the ground :)
Badboy
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Hi Haa,
>First of all, try this link: http://www.simhq.com/simhq3/sims/air_combat/energymgmt/index-pf.html (http://www.simhq.com/simhq3/sims/air_combat/energymgmt/index-pf.html)
The longest explanation I've ever seen how to beat an inferior turning plane in a turnfight :-)
>Before I do that I would appreciate some feedback on my method.
Looks good :-)
I think the following conclusion from Bernoulli's law might be useful:
n~v^2
(n = load factor/"Gs")
With the right constant, the curve should run nicely through your data points until maximum Gs are reached.
Regards,
Henning (HoHun)
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Originally posted by HoHun:
The longest explanation I've ever seen how to beat an inferior turning plane in a turnfight :-)
It always seems that way when you read something you already know :-)
Dweeb
[ 09-10-2001: Message edited by: Dweeb ]
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Some planes had their flight envelopes printed in their manuals, like some F4U and P-38 models (mainly for comressebility issues). It should be noted that the presentation in these is traditional V-G diagram which IMHO is more clear than V-dps presentation. The flight envelope changes with the altitude, I don't know if this modeled in the AH?
gripen
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Hi Dweeb,
QUOTE]Originally posted by Dweeb:
It always seems that way when you read something you already know :-)[/QUOTE]
Direct hit! :-)
I remember how excited I got 6 years back when I discovered the first doghouse plots drawn by Stu Butts on Compuserve's FSFORUM. (Still got them on my HD, too :-)
Badboy was on FSFORUM then, too, and as one of the half dozen top experts there taught me all the important things one's got to know.
Big thanks, Badboy! :-)
Henning
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Originally posted by Badboy:
I don't think a complete exposition exists at the moment, but it is planned. I'm currently in the process of completing a writing project for a jet sim and as soon as that is done I'll start work on a set of diagrams like this one that contains all of the information you mentioned and much more:
Sounds great... I'll look forward to it.
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Originally posted by CyranoAH:
BTW, punto also means "knitwear" :)
el knitwear
Has a ring to it. Think I'll use that from now on to punt threads. Thanks Cyrano
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Originally posted by Badboy:
I don't think a complete exposition exists at the moment, but it is planned. I'm currently in the process of completing a writing project for a jet sim and as soon as that is done I'll start work on a set of diagrams like this one that contains all of the information you mentioned and much more:
I hope to do that for all of the aircraft in AH, They will be made available on the AH web site.
Badboy
Badboy, if it would help you I can send you the data I have collected so far. Basically like the La5 data above, although some planes with various flap settings and bomb loads as well. I have tested the following planes, all at 1k alt with 25% fuel:
British: Spit V, Spit IX, Seafire, Typhoon, Tempest, Lancaster(!)
Russian: La5, La7, Yak-9U, Yak-9T, Il2m3
Italian: C.202, C.205
Japanese: A6M5, Ki-61, N1K2-J
German: Bf109F-4
US: P-47D-11
Offer is open to anyone interested. Or someone could help me post the diagrams here. How do I put an image here anyway?
/haa
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Originally posted by HoHun:
>Before I do that I would appreciate some feedback on my method.
Looks good :-)
I think the following conclusion from Bernoulli's law might be useful:
n~v^2
(n = load factor/"Gs")
With the right constant, the curve should run nicely through your data points until maximum Gs are reached.
Regards,
Henning (HoHun)
Thanks Henning! It fits very well for most of the planes! There are a couple of planes showing different behaviour, but maybe I can write that off as due to inaccuracies in my testing.
As an added bonus I get a good estimate of the stall speed. Most useful, thanks again.
/haa
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HAA, Hammer from the Nazgul might be interested in your data for his website.
xBAT
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Hi Haa,
>Or someone could help me post the diagrams here. How do I put an image here anyway?
I think the usual way to do it is to upload the diagram to some place on the web, for example the webspace typically reserved for you by your internet service provider (ISP).
Once you've uploaded your image, it'll have a URL like
http://for.example.its/~haa/diagram.jpg (http://for.example.its/~haa/diagram.jpg)
Just hit the image button in the reply window, then insert your image URL into the window that pops up, and the image should display just fine in your message :-)
I'm looking forward to it!
Regards,
Henning (HoHun)
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La5 EM diagram:
(http://medlem.tripod.spray.se/haa/la5.gif)
It worked! :)
More diagrams are on the way...
[ 09-17-2001: Message edited by: haa ]
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Here they are. The data is in a zipped Excel file at:
EM.zip (http://medlem.tripod.spray.se/haa/EM.zip)
Enjoy!
/haa
(http://medlem.tripod.spray.se/haa/A6m5.gif)
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(http://medlem.tripod.spray.se/haa/Bf109F.gif)
(http://medlem.tripod.spray.se/haa/C202.gif)
(http://medlem.tripod.spray.se/haa/C205.gif)
(http://medlem.tripod.spray.se/haa/Il2m3.gif)
(http://medlem.tripod.spray.se/haa/Ki61.gif)
(http://medlem.tripod.spray.se/haa/La5.gif)
(http://medlem.tripod.spray.se/haa/La7.gif)
(http://medlem.tripod.spray.se/haa/Lancaster.gif)
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(http://medlem.tripod.spray.se/haa/N1K2J.gif)
(http://medlem.tripod.spray.se/haa/P38L.gif)
(http://medlem.tripod.spray.se/haa/P47D11.gif)
(http://medlem.tripod.spray.se/haa/SeafireII.gif)
(http://medlem.tripod.spray.se/haa/SpitfireIX.gif)
(http://medlem.tripod.spray.se/haa/SpitfireV.gif)
(http://medlem.tripod.spray.se/haa/Tempest.gif)
(http://medlem.tripod.spray.se/haa/Typhoon.gif)
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(http://medlem.tripod.spray.se/haa/Yak9T.gif)
(http://medlem.tripod.spray.se/haa/Yak9U.gif)
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Hi Haa,
hey, that was pretty quick :-)
The diagram is looking very nice, I'm really impressed!
If you'd calculate an average maximum lift factor from the values that didn't hit the G limit, you'd arrive at a smooth graph instead of the scattered data points you have now. This smooth graph would probably hit the G limit line at about 36 degrees per second and 310 mph IAS.
If you'd continue the graph to the right, you'd hit the structurally allowable top speed, sloping down from some value at 9G to a higher value at 1 G. For example, at 350 mph IAS the La 5FN seems to withstand 9 G, at 400 mph IAS it might only withstand 6 G, and 500 mph IAS may be the absolute maximum at 1 G. (At higher altitudes, the limit may be determined by compressibility considerations rather than by structural ones.)
By the way, if (as Gripen already suggested)you'd plot the diagram in a more conventional fashion with the load factor on the vertical axis instead of the turn rate, you'd arrive at a less spectacular but easier to read diagram :-)
Regards,
Henning (HoHun)
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Hi Haa,
here's an example for the processing of the raw data I mentioned:
(http://members.aol.com/hohunkhan/p47.gif)
Note that I calculated the value of the corner speed, as clearly visible in the shape of the curve :-)
So far, the characteristic values for the P-47 to be learned from this diagram are
- corner speed
- maximum load factor
It does not yet make a statement on the energy combat capabilities of the P-47, however.
Regards,
Henning (HoHun)
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Heya,
I think the 3G portion of the graph is sustained turn rate. But I'm not sure any of these birds can maintain a 9g turn. What is the criteria for the graph?
Also could you throw in the F4U-1D, F6F and P-51 :D
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Hi F4UDOA,
>I think the 3G portion of the graph is sustained turn rate.
In Badboy's diagram, it is.
>But I'm not sure any of these birds can maintain a 9g turn.
Not without losing energy, so much is certain :-)
>What is the criteria for the graph?
It portrays the limits of the aircraft's envelope.
Since the P-47 reached but didn't exceed 9 G in Haa's test, it can be taken to be one of the limits of the P-47's envelope. The 6 G limit in Badboy's graph is misleading as you can fly beyond that limit.
Whether you should is another question :-)
Regards,
Henning (HoHun)
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I think the 3G portion of the graph is sustained turn rate. But I'm not sure any of these birds can maintain a 9g turn. What is the criteria for the graph?
See my first post in this thread.
Also could you throw in the F4U-1D, F6F and P-51 :D
This is where I am hoping someone will say: "Hey, this looks easy. I can test a couple of planes and save haa from doing it all by himself"... :)
/haa
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Originally posted by HoHun:
Since the P-47 reached but didn't exceed 9 G in Haa's test, it can be taken to be one of the limits of the P-47's envelope. The 6 G limit in Badboy's graph is misleading as you can fly beyond that limit.
Actually, the G-meter only goes up to 9 G. You can probably pull more g's but it doesn't show on the meter.
I find it interesting that the blackout at 6 G only causes a loss of vision. I am still able to perform maneuvers ( = evasives etc ).
/haa
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Hi Haa,
>Actually, the G-meter only goes up to 9 G. You can probably pull more g's but it doesn't show on the meter.
Oh, I wasn't aware of that. In real life, you'd want to have the accelerometer to exceed the limitations of your aircraft - which typically were something like 7 G with a safety factor of 1.5.
Any idea on how to establish the maximum load factor actually achievable? (Perhaps a high-speed spiral dive to record time for a 180 degree turn at maximum Gs?)
I noticed some planes on your list didn't exceed 8 G, though.
>I find it interesting that the blackout at 6 G only causes a loss of vision. I am still able to perform maneuvers ( = evasives etc ).
The elite of the aerobatic pilots seem to perform their manoeuvres at up to +10/-5 G without a G suit at all. I think G induced loss of consciousness (GLOC) depends on more factors than load factor alone - the most important apparently being duration and onset rate.
Regards,
Henning (HoHun)
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Here are a few more...
/haa
(http://medlem.tripod.spray.se/haa/Fw190A5.gif)
(http://medlem.tripod.spray.se/haa/Fw190A8.gif)
(http://medlem.tripod.spray.se/haa/Ta152.gif)
(http://medlem.tripod.spray.se/haa/F4U1D.gif)
(http://medlem.tripod.spray.se/haa/F6F5.gif)
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Hi Haa,
great to see you've completed another series of tests!
As in any experiments, the data points you've measured display a small random error, so I'd suggest to create an average graph eliminating these errors by averaging each data points v^2/n value and using it as the basis for the corrected graph.
It could look like the one I recently prepared:
(http://members.aol.com/hohunkhan/p47.gif)
Here's another graph from the same set of data, preseting the results in a way that's better suited for discussion:
(http://members.aol.com/hohunkhan/p47_2.gif)
As you can see, I've plotted maximum G rate over speed directly, using the average from your measurements. For sake of the illustration, I've assumed 9 G to be the structurally permissable maximum load.
Additionally, I've made up the term "orthogonal turn rate" for the turn rate that can be achieved without caring to keep the turn level, i. e. when pulling into a turn from a 90 degree bank, and to hell with gravity! ;-)
What does this graph tell us? Corner speed coincides with the lowest speed at which the maximum G rate can be achieved. No surprise here!
We also see that corner speed is very close to level maximum speed, which is one reason not to spend too much energy memorizing corner speeds. A high-performance turn at corner speed will eat up energy so quickly that speed will drop anyway, and since the turn rate slope is quite similar on both sides of corner speed, you'll simply want to go as fast as possible to get the best possible turn rate for the longest time.
Jets are so much faster that they can be very far beyond corner speed, suffering a serious manoeuvrability penalty, but in propeller fighters, this is usually not a concern.
Keep in mind that the speed is indicated airspeed, and the graphs are for low altitude. At greater altitudes, your top speed will be an even lower indicated airspeed, so that you'll be operating below corner in most cases anyway.
Another feature of our graphs is that the orthogonal turn rate grows linearly with speed (up to corner speed, of course). This may seem surprising at first, but with centripetal acceleration a ~ v^2 and turn radius r ~ v^2/a => r ~ a/a = const, we arrive at a constant turn radius regardless of speed. If you're going along a constant radius, any increase in speed will obviously result in a linear increase in turn rate, too.
If you know 1 G stall speed and the permissable maximum G rate of an aircraft, you have enough data to draw such a diagram for the aircraft in question. There's not that much to learn from it, since the aircraft with the lower 1 G stall speed will inevitably have a higher (or at least equal) turn rate anywhere in the diagram. Only if it suffers from a lower permissable maximum G rate it might fall off in the high-speed range, but I think the limits of all WW2 fighters were pretty similar.
Of course, if you add energy data, the diagram will become more interesting again :-)
Regards,
Henning (HoHun)