Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: artik on August 25, 2013, 04:44:20 PM
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On the deck 50% fuel (P-51D 25%), WEP+
360 degree turn time in seconds:
| Plane | 200mph | 250mph | 300mph |
| Yak-3 | 19.5 | 23.2 | 31.9 |
| Spit 14 | 19.2 | 23.0 | 30.6 |
| La-7* | 21.2 | 22.5 | 28 |
| 109K | 22.7 | 26.0 | 30.1 |
| P-51D | 21.9 | 25.2 | 33.8 |
* Not too accurate
It is damn hard to keep speed and altitude constant. In most of cases alt +- 50 feet speed += 10mph
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Added G force and turn radius
Plane 200mph 250mph 300mph
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t G R t G R t G R
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Yak-3 19.5 2.95 280 23.2 3.1 410 31.9 2.7 680
Spit 14 19.2 3.0 270 23.0 3.1 410 30.6 2.8 650
La-7* 21.2 2.7 300 22.5 3.2 400 28 3.1 600
109K 22.7 2.5 320 26.0 2.7 460 30.1 2.9 620
P-51D 21.9 2.6 310 25.2 2.9 450 33.8 2.6 720
t - time of 360 turn seconds
G - G-load
R - radius of turn - meters
I'll try to add more in near future and refine measurements I can
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artik, what are you measuring at speed? Trying to maintain the same speed in the turn?
Or are you starting at a speed, and doing 1 360 turn?
HiTech
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Ohh this is hard
I do left turn low over the water so I have good visual height reference.
I keep E6B open to see the speed and I try to maintain it as constant as possible while also keeping altitude.
It is very hard and in general I manage to keep the speed +- 10mph and alt +-50 feet - for La7 I didn't do it so well that it is marked by *
All is done using AHF recording. I do several circles. Than in AHFV I measure time for each circle and than take an average.
I don't always succeed but it is the best I can manage. I assume test pilots can do it better :) - I'm still learning to be AH2 test pilot :x
It would be cool to have offline autotrim on sustained turn ratio :-)
Edit: I can attach a link to sample test if you want.
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Added G force and turn radius
Plane 200mph 250mph 300mph
---------------------------------------------------------------------------
t G R t G R t G R
---------------------------------------------------------------------------
Yak-3 19.5 2.95 280 23.2 3.1 410 31.9 2.7 680
Spit 14 19.2 3.0 270 23.0 3.1 410 30.6 2.8 650
La-7* 21.2 2.7 300 22.5 3.2 400 28 3.1 600
109K 22.7 2.5 320 26.0 2.7 460 30.1 2.9 620
P-51D 21.9 2.6 310 25.2 2.9 450 33.8 2.6 720
t - time of 360 turn seconds
G - G-load
R - radius of turn - meters
I'll try to add more in near future and refine measurements I can
:airplane: Good post! I would like to see your measurements of constant 3G turns, at constant altitude. Airspeed is going to decay somewhat when first entering turn, but after a constant 3G, speed should stabilize, as we have no heat thermals or wind to content with in AH2. (assuming a 500 foot altitude).
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:airplane: Good post! I would like to see your measurements of constant 3G turns, at constant altitude. Airspeed is going to decay somewhat when first entering turn, but after a constant 3G, speed should stabilize, as we have no heat thermals or wind to content with in AH2. (assuming a 500 foot altitude).
There are two major problems with a constant 3G.
1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.
2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha) where alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree - barely visible
On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.
The turn speed can be measured with stopper easily
This makes constant speed/altitude turn speed measurement much easier (but still very hard:
This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf
You can see that it is very hard to keep the steady flight parameters and they fluctuate.
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The game's E6B is an interface in real time reveling the active data sets Hitech chose to make available. He could have made this available as another HUD like the damage list or FPS counter. Since so many players over the years have spent countless hours offline attempting to manually create speed, climb and turn rate charts a la Wright Bros and a stopwatch.
You could ask Hitech for an "offline only" HUD like tool to assist you in gathering more accurate data. I suspect for development and testing Hitech has a developer mode with everything you would ever want to see in an active HUD display along with logs to review. OR, Log Mode in which you use hot keys to start and stop active logging while you pull turns, climb and fly speed tests. OR, Hitech could make that a component of the film viewer so you can playback in data mode along with generating a log file to build your speed, climb and turn charts from.
It couldn't hurt since these ongoing efforts may be a passive trouble shooting vector that helps Hitech keep track of his aircraft physics modeling visa watching the forum. Worst case, more forum fights over "my data is better than your data".
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There are two major problems with a constant 3G.
1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.
2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha) where alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree - barely visible
On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.
The turn speed can be measured with stopper easily
This makes constant speed/altitude turn speed measurement much easier (but still very hard:
This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf
You can see that it is very hard to keep the steady flight parameters and they fluctuate.
:airplane: Ok, one fact that you cannot get away from is this: If you go into a turn and establish a 3G turn, 2 things are going to happen: #1 unless you add power during the turn, the airspeed is going to decay! #2- unless you add power to maintain your desired airspeed, then the AOA will be constanty changing in order to maintain your altitude. The only way to do the tests, as I see it, is to go into the turn at say, 75% power, using the other 25% to adjust your airspeed as it decays and or to hold your altitude. In straight and level flight, you are pulling 1G, in a 30 degree bank, 1.5G's and a 60 degree bank, 2G's, so you are going to have to start with a 90 degree bank and back pressure on the "stick" to get to the 3G factor and without adding power, your altitude and airspeed are going to be decaying during the whole turn. But, thanks for sharing what you did with us!
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There are two major problems with a constant 3G.
1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.
2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha) where alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree - barely visible
On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.
The turn speed can be measured with stopper easily
This makes constant speed/altitude turn speed measurement much easier (but still very hard:
This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf
You can see that it is very hard to keep the steady flight parameters and they fluctuate.
It takes a lot of practice to get good at sustained turning. Like Mosq, I've tested everything. With few exceptions, we usually get numbers that are very close.
Now, here's a tip towards making it much easier to test the Yaks... Turn right instead of left. By going right, you're not fighting torque and you'll have less trouble being consistent.
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Now, here's a tip towards making it much easier to test the Yaks... Turn right instead of left. By going right, you're not fighting torque and you'll have less trouble being consistent.
Spit XIV, Tempest and Typhoon as well.
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One other thing I thought of is to create several areal circles that are very easy to follow - such that you would have an exact flight path you can follow without looking that the gauges.
Maybe some sort of torus sharped cloud with big radius but very thin - something like that.
Such that you fly at constant=alt/turn-radius on full power and see at what speed you get stabilized.
Is there any way to create such a circular path that would be easily visible by the pilot?
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Hummmm...not meaning to dismiss your good work artik but why not just use the EM diagrams Badboy (and I think some others) produce? You can read all that info (and more) directly off the chart. This chart has the P-51D and Yak-9U (sorry, couldn't find a copy with just the Pony.)
To use this for a stabilized level turn (i.e., constant speed, constant G), just pick your speed at the bottom and then go vertically to the Ps=0 line. From that point you look across to the left and you can read the Degrees per Second (DPS). Follow the curved G line to determine your available G and follow the diagonal lines to determine radius.
So, for the P-51D at 200mph with 25% fuel, at sea level and mil power we get: 17DPS, 2.8G and 1000ft radius. Convert that to a 360 degree turn and meters and you get 21.2 sec for a 360deg turn at 2.6G with a radius of 304 meters. Also, as others have asked regarding numbers associated with a specific G, the chart can do that as well. Let's pick 3G. Follow the 3G line to where it intersects the Ps=0 line (ok, it's just a tiny bit away from intersecting but close enough for government work) and we get 250mph. Degrees per second is 14 (25.2 sec for 360deg) with a radius of 1,500 ft (457 meters).
These charts can also tell you lots more. For instance, you can't sustain a level turn above 3G at all (it's all above the Ps=0 line so you don't have enough power to sustain a level turn above 3G). Also, if you're at full power at a constant 2g level turn you'll accelerate to about 345mph (you're below the Ps=0 line so you have excess Power). You can also lots of other things, for instance your available instantaneous turn rate anywhere in the envelope (23DPS at 325mph with a 1200ft turn radius) and lots more...it's like magic! It's not only easier than doing a flight test for every number you'd like to know there's no math required.
All that said, there really isn't much use for numbers like constant speed and G other than where they are maximized. In ACM you always strive to maximize your plane's performance either in acceleration or turns so these "in between" numbers aren't as useful as say, corner and max sustained speeds. Generally speaking, you're either trying to accelerate in a straight line or using your maximum performance instantaneous or sustained turn rates. If you aren't max performing your turns you increase your radius (called "arcing"). Arcing will often give your opponent an advantage as he can more easily position himself within your turn radius to cut you off or lead turn you. That said, it's certainly interesting and beneficial to study these types of performance numbers as they show you the tradeoffs you make when you don't max perform your plane.
(http://i71.servimg.com/u/f71/15/52/34/74/diagra10.jpg)
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Nice, that is what eventually I wanted to have (I was searching for something like that but hand't found).
Questions:
- Were do I get these diagrams/data?
- How they had they been generated?
- Are there similar diagrams for different altitudes?
BTW what is cool that I got relatively close data using flight testing...
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http://www.leonbadboysmith.com/Files/AH_BootStrap.zip (http://www.leonbadboysmith.com/Files/AH_BootStrap.zip)
Think thats what you are looking for Badboy's Bootstrap Calc?
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Artik the turn rate data comes from flight testing. It's very difficult to get it exactly right but you only need to get close to have useful information.
Typically for best sustained turn you'll be pulling between 2.5 and 3 Gs at the slowest speed which allows that G load. You can pull harder and go slower but you won't turn as fast. You can see that on the EM diagram. Sustained turn rate peaks at 170 mph for the P-51 and 160 mph for the Yak. Going slower drops the turn rate as does reducing G load.
You won't know if you want 2.5 or 3 Gs or something in between until you fly it and time it. The speed and G combination that gives you the best sustained turn rate in a particular WW2 fighter aircraft will likely be more than 2.5 G and slower than 200 mph. If you see 2.8 G and hear the stall horn you're likely close to your best turn.
It's useful to go faster than your best sustained turn speed so that you have energy for vertical maneuvers. If the bandit gets too slow from max turns he won't be able to follow you up.
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Artik the turn rate data comes from flight testing. It's very difficult to get it exactly right but you only need to get close to have useful information.
Typically for best sustained turn you'll be pulling between 2.5 and 3 Gs at the slowest speed which allows that G load. You can pull harder and go slower but you won't turn as fast. You can see that on the EM diagram. Sustained turn rate peaks at 170 mph for the P-51 and 160 mph for the Yak. Going slower drops the turn rate as does reducing G load.
You won't know if you want 2.5 or 3 Gs or something in between until you fly it and time it. The speed and G combination that gives you the best sustained turn rate in a particular WW2 fighter aircraft will likely be more than 2.5 G and slower than 200 mph. If you see 2.8 G and hear the stall horn you're likely close to your best turn.
It's useful to go faster than your best sustained turn speed so that you have energy for vertical maneuvers. If the bandit gets too slow from max turns he won't be able to follow you up.
:airplane: I would think that most useful info for a player in Aces High would be this: establish a 60 degree bank, at 200MPH IAS, 250MPH and 300MPH, and see how long in seconds it would be required to make a 180 degree turn! Looks to me like that info would be the most useful in ACM's. Same thing with spilt "S", or an Immelmann turn. Not sure, but how quickly one could turn into an opponent would be of some value in ACM's.
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:airplane: I would think that most useful info for a player in Aces High would be this: establish a 60 degree bank, at 200MPH IAS, 250MPH and 300MPH, and see how long in seconds it would be required to make a 180 degree turn! Looks to me like that info would be the most useful in ACM's. Same thing with spilt "S", or an Immelmann turn. Not sure, but how quickly one could turn into an opponent would be of some value in ACM's.
FLS and I both were explaining those numbers that are most useful. There are actually three turn performance numbers that are most important to a fighter pilot in ACM. These are sustained and instantaneous turns rates and turn radius all of which can be pulled from the EM diagram.
On the EM diagram I posted (we’ll only talk the P-51 for simplicity), the left hand red line is the lift limit line. Go to the left of this and you'll stall. The upper line is your G limit line. Pull more than this and you'll damage your ride (or, in AH, you'll black out). The middle red line is the Ps=0 line. Spelled out that's the “Specific Excess Power equals Zero” line and it divides the chart between excess engine power and insufficient engine power. If you’re anywhere on that line you can keep doing what you’re doing without climbing or descending. Above the line you have less power available for sustained performance and below the line you have more power available. Your best sustained turns are where this line intersects the lift limit line and your best instantaneous turn occurs at corner velocity where the lift limit line intersects maximum G limit line. At any point you can follow the radius lines on the chart to determine turn radius for that particular combination of G and speed.
You can see that the P-51D’s best sustained level turn is at 170mph which gives you an 18 degrees per second turn rate at about 2.7G and an 800ft turn radius. Anything below the Ps=0 line gives you less sustained turn performance but what you would find is you have more power than you need for a sustained level turn. If you pull to the edge of stall at say, 125mph, that excess power means that you will start out turning at about 10DPS (just draw a vertical line from 125mph to where it intersects the lift limit line) but will gradually accelerate to your best sustained turn at 170 giving you improved sustained turn performance. This part is particularly interesting in that many people mistakenly believe that the slower you are the tighter you can turn but look at the radius for 125mph, it’s 1000ft while at your best sustained turn speed of 170mph the radius has decreased to 800ft.
Above the Ps=0 line you can see that pulling to the edge of stall (the lift limit line) gives you a greater turn rate and even smaller radius. This is due to the greater G available as a result of your speed but you don’t have the power to sustain this turn (you’re above the Ps=0 line) and you’ll rapidly decelerate so, since you can’t sustain the turn rate, it's called instantaneous turn rate. Say that your speed is 225mph. If you pull hard at that speed you can see that your instantaneous turn rate is 25dps (just follow the 225mph line up to where it intersects the lift limit line again) with a turn radius of about 760 ft. That higher turn rate is a direct result of having more G available to you, in this case, about 4.5G but since you don't have the power to overcome the induced drag created by pulling all those G's you'll decelerate rapidly along the lift limit line right down to your best sustained turn speed of 170mph.
Your absolute best instantaneous turn performance is where the lift limit line intersects the G limit. Increasing G increases your turn rate and decreases your radius but only up to the G limit. You can only pull the maximum amount of G that the airplane can handle otherwise you’ll break your ride (or black out). That’s why corner is the best turn rate and smallest radius you’ll ever get (that’s for an actual turn, not a maneuver like a vertical rudder reversal). For the Pony you can see that corner is about 255mph giving you almost 32dps at 6G with about a 750ft radius. That turn rate is almost twice what you can sustain unless you’re in a descending turn. If you stay level, you’ll ride the lift limit line right back down to 170mph. If you’re faster than 255mph aircraft performance is limited by the airframe’s G limit and again, from the chart, you can see that your turn rate is less than at corner and your radius rapidly increases.
So, to go back to your comment, the most important numbers to know you can get from this chart. Your best sustained turn rate, corner velocity and turn radius.
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^^^^
Thank you Mace,as always an excellent analyst and explanation.
:salute
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Is there a version of the EM Diagram with a legend to hold nest to the plane specific generated diagrams?
(http://navyflightmanuals.tpub.com/P-821/P-8210203im.jpg)
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:airplane: I would think that most useful info for a player in Aces High would be this: establish a 60 degree bank, at 200MPH IAS, 250MPH and 300MPH, and see how long in seconds it would be required to make a 180 degree turn! Looks to me like that info would be the most useful in ACM's. Same thing with spilt "S", or an Immelmann turn. Not sure, but how quickly one could turn into an opponent would be of some value in ACM's.
Turn rate is a function of speed and radial G. A 60 degree bank level turn is a 2G turn in any aircraft. A 2G turn at 200, 250, or 300 mph gives the same turn rate in any aircraft. The EM diagram shows you that the turn rates are 17, 8.5, and 7 degrees per second.
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Does anybody have a references for the real world (not simulator) sustained turn ratio at sea-level altitude?
I just noticed that in IL-2 the maximal sustained turn rate of P-51D-30 almost as high as 3.9G and none of P-51D variant goes below 3.5G maximal sustained turn rate. In AH-2 it passes 3G only by a margin.
I just wanted to see a reference to real world data at sea level.
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Turn rate is a function of speed and radial G. A 60 degree bank level turn is a 2G turn in any aircraft. A 2G turn at 200, 250, or 300 mph gives the same turn rate in any aircraft. The EM diagram shows you that the turn rates are 17, 8.5, and 7 degrees per second.
:airplane: You are correct, but the reference I was making that as a pilot in a fighter in this game, not RL, if an opponent is 1.5 K behind me and I am doing 250IAS, and I know that his speed is probably around 300 to 350 because he is closing, do I have enough time to execute a 180 degree turn and engage without putting myself at a disadvantage or should I dive away to gain speed, or would an Immelmann turn be best to engage the on coming opponent, or maybe a split S.
I realize that the type of aircraft approaching your "6" would have some bearing on what to do, I for one, would like to know what my options are as quickly as possible.
I have trouble now with fighters in this game I love so much, because I have only 10% in my left eye and about 80% vis in my right eye, so that is why I prefer bombers 95% of the time.
I would still be flying my beloved Kingaire 200 today, at age 79, but in 1998, I realized my eyesight was going away in my left eye, and I could not in good faith put my passengers in danger just to feed my love for flying!
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As I mentioned in my thread on sustained turns, there's a good primer on BadBoy's EM Diagrams here. http://www.simhq.com/_air/air_011a.html (http://www.simhq.com/_air/air_011a.html)