Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: F4UDOA on July 26, 2000, 11:10:00 AM
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Gents,
I have to say that in the online simm market these day's the FM in AH seems to offer the most in ACM because their really is no Uber plane, no turn wonder or any one A/C that clearly does anyone thing better than the others all the time. My question is this.
Is this accurate?
I fly the F4U-1C or D exlusively and I have noticed that in an offensive situation that there is no A/C that can turn tight enough horizontally to prevent me from staying on their 6 and closing in a Co-E fight(haven't tried the Zero but I have the Spit). In other simms this is not the case. If I were to try to flat turn on the deck with a Spit9 in AW I would be dead in three turns. I have less experiance in WB but I believe the same to be true. I have also noticed the inverse to be true. If I try to evade a P-47 on the deck using flat turns I cannot excape. Nor can I escape a P-51 or FW190 (The P-47 and FW190 have very high wing loading). I have killed and been killed by the same A/C in the same flat turning situation. Is their some kind of design parity amoung the fighter A/C in AH that prevent one A/C from gaining an edge on the other. In combat evaluations of all of these A/C, one of the critical factors in all test was turning ability and minimal turn radius. It was very important in both offense an defense. As it was important for the pilots to be aware of just what A/C they were opposing. This is does not seem to be a factor in AH either by design or not.
Pyro/HT
You mentioned that you were looking into some things in your physics model that may slow the turns down. Have you looked in this?
Did you find anything?
Thanks
F4UDOA
[This message has been edited by F4UDOA (edited 07-26-2000).]
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Originally posted by F4UDOA:
Gents,
Pyro/HT
You mentioned that you were looking into some things in your physics model that may slow the turns down. Have you looked in this?
Did you find anything?
Hasn't been done yet, but it's still on the to do list for 1.04.
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Doug "Pyro" Balmos
HiTech Creations
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Thanks Pyro
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One thing to keep in mind.. always:
Fuel levels.
It is impossible to use anecdotal evidence IMHO because you never know the exact situation the other guys are in.
I fly a P47D. Trust me... if I horizontal turn I can kiss my bellybutton goodbye in about a 30-60 seconds. <G>
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Lephturn - Chief Trainer
A member of The Flying Pigs http://www.flyingpigs.com (http://www.flyingpigs.com)
(http://tuweb.ucis.dal.ca/~dconrad/ahf/lepht.gif)
"My P-47 is a pretty good ship, she took a round coming 'cross the Channel last trip.
Just thinking 'bout my baby and lettin' her rip, always got me through so far."
- Steve Earl
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Lephturn,
Your right, if you flat turn a Jug on the deck you should expect to die quickly. And if I were on your tail in a F4U-1D you would. However in the case of these two A/C I should also be able to escape from that same P-47D30 in a flat turn. You mention fuel loads affecting the outcome. Well here is a break down on that subject.
P-47D30loaded weight 100% internal fuel
14411LBS
Wing area=300Sq Ft
Weight of fuel 2220lbs
Wingloading
100%fuel=48.03
25% fuel= 41.48
F4U-1D loaded weight 100%fuel
11962LBS
Wing Area=314Sq ft
Weight of internal fuel 1422LBS
Wingloading
100%Fuel=38.09
25% Fuel=32.04
So even with the P-47 at 25%Fuel and the F4U at 100% Fuel the F4U is still better by a fair margain. With compairable fuel loads this is not even close. You may say the 2600HP help the P-47 through a turn but the weight and the high drag are worse than the F4U. It is not my intent in this thread to start ranting about the F4U again since I don't think that this is limited to the F4U.
I think that there is an across the board issue with turn rates. My issue with the F4U is that I believe either the drag or weight to be off affecting E-retention, turn rate and accelleration. But that is a topic for another thread.
Later
F4UDOA
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the CLmax of the airfoil is important too F4U.
for example, if you were to compare a spitfire with a wingloading of 38 lb/ft^2 and a f4u with a wingloading of 38 lb/ft^2 thw spitfire would still outturn the hog since inch for inch the spitfire wing produces more lift because of its planform. Plus, like u said power loading comes into play.
And, it is always MUCH easier to turn when you are on offense rather than defense. On offense, you must break as hard as you can and waste e, while if on ffense you can yoyo a bit and wear the other guys e down.
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Zigrat posted:
And, it is always MUCH easier to turn when you are on offense rather than defense. On offense, you must break as hard as you can and waste e, while if on ffense you can yoyo a bit and wear the other guys e down.
I think he ment to say:
And, it is always MUCH easier to turn when you are on offense rather than defense. On defense, you must break as hard as you can and waste e, while if on offense you can yoyo a bit and wear the other guy's e down.
Sisu
-Karnak
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I have put much thought into this subject.
At first glance something does seem off kilter but I must acknowledge that the turn rate of ANY plane in AH is very dependant on speed. Each plane has a comfort zone where turns are sharpest, problem is, when turning, speed is lost -therefore, the comfort zone is fleeting.
Fly smart!
Yeager
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F4UDOA,
Zigrat, your right about the max Cl of the wing making a difference in a turn. But I don't know if the result would help a P-47 pilot much. Most WW2 fighters had a no flaps Cl of between 1.4 and 1.5. the No flap Cl of a F4U is approx. 1.48 and it has a 1G stall of 100MPH clean. The Spitfire prob had a similer max Cl. The advantage of the Spit wing was the elliptical shape reducing Cdi or induced drag allowing it to move through turns more quickly with less loss of E. The F4U had maneuver flaps at low speed which increased drag but raised the lift coefficient to 1.88(It was 2.33 in early F4U's) allowing the F4U to turn at very low speed. The P-47 had a similer Cl to the F4U but had very high wing loading giving it a clean stall of 115MPH. If you multiply that times the 1.73(square of the G factor) it will give you the 3G stall 199.18mph. The F4U clean 3G stall is 173.2MPH. I will solve for the Cl of both the P-47 and F4U tommorrow but I guess my point is that there was no parity in turning ability of WW2 fighters. However in AH there seems to no advantage to having a superior turning radius. That's all.
<S>
F4UDOA
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Great topic F4UDOA,
Quote: "However in AH there seems to no advantage to having a superior turning radius. That's all."
Exactly my problem also. There were huge turn differences in these aircraft. Not the case in AH. Here is a quote from Hitech:
""We are continuing to look into the matter and have some idea's and test we might run to see if a change to a few items wil enhance the sustained turn rate accuracy Write now I feel it could be off but realy havn't seen any real evidence that it is."
AH is a great sim with a great FM. But, one of the reasons I have not signed up for an account to play on-line is for that reason. Turn ability seems too similar across the board. I fly the P-47 alot in WB and AH off-line. They feel allmost identical. But why do the other AH aircraft not change in FEEL? I`m not talking about energy managment (which is very important and I do well), I`m talking turn rates between aircraft.
Here is a awesome topic on this subject. A very constructive and mature (mostly (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)) disscussion. This is not a "flame war" thread, please do not turn it into one.
http://agw.dogfighter.com/agw/Forum3/HTML/013132.html (http://agw.dogfighter.com/agw/Forum3/HTML/013132.html)
The thread is 5 pages long. If you have the time to read ALL 161 POSTS then please feel free to add something constructive here. If not, then don`t reply.
It`s just that I see alot of AH players making uneducated FM claims without facts on this board. I can`t tell you how many times I see people preach AH realism and WB arcadism. Or that one is more difficult than the other, Pure BS. Get educated about both sims, learn the facts, then you can contribute something to your community.
Thanks, and look forward to flying AH in the future.
Great time to be a sim pilot isn`t it. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
PS: F4UDOA, alot of the information you may be looking for is on pages 3, 4, & 5.
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Mavric ~ X.O.
WB 325th FG
[This message has been edited by mavric (edited 07-27-2000).]
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Originally posted by F4UDOA:
If I try to evade a P-47 on the deck using flat turns I cannot excape. Nor can I escape a P-51 or FW190 (The P-47 and FW190 have very high wing loading).
methinks you're underestimating Fw190 (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
(it is not dora..)
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On the subject of turn performance and comparisons...
This is not an easy subject to put into 25 words or less. There are many factors that enter into the subject...enough to make the whole thing hard to get a handle on.
Comparative turn performance is simply not a matter of comparing factors such as wing loading or lift coefficients (Cl). While these may be important, there is often more to the picture...a lightly loaded B-52 has a very low wing loading and a high Cl, but I wouldn't exactly call it a BFM monster!!
There is no easy answer. And going to the real world is sometimes risky since a sim's FM programming may or may not have any fidelity to the RL airplane. Just look at the A-10 in Janes USAF as a good example of a lousy sim FM...but it sure can turn!!
I'm including a graph known as an 'energy diagram' that a friend made for me. It is an example of the type of info that we would have to have on AH aircraft in order to make any comparisons.
Once we pick an aircraft type, we first stipulate the altitude, configuration, and gross weight. In comparing aircraft, these conditions must remain the same.
Then we can look at the diagram and derive some general info. The peak of the flight envelope represents the max instantaneous G that can be pulled at the lowest speed...this is Corner Velocity. The 'Ps=0' line gives us a look at energy conservation. The higher up a particular aircraft's Ps=0 line is on this chart, then the better performer it will generally be. Why? Because it will be able to sustain more G at a lower airspeed that others...this gives it a smaller sustained turn radius and higher sustained turn rate.
In RL fighters, we would take the energy diagrams of two aircraft and overlay them to see the differences. In doing so, we could get some general info...such as don't slow down with a MiG-21 unless you are in another MiG-21! But no one ever won a fight with an energy diagram. These are tools to help get a grasp of the big picture...nothing more.
For us to understand relative turn performance in AH aircraft, we would start with diagrams such as this.
Andy
(http://www.doitnow.com/~alfakilo/EM1.jpg)
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"However in AH there seems to no advantage to having a superior turning radius"
Thats why I love AcesHigh, even tho I love early war plane sets. Thats why, IMHO, AH is less different from the Real Thing than other online sims. Better turning performance should not always give more chances to survive.
Faster and more armed fighters have always won. Its only a matter of patience ... maybe you need one or two more passes ... but in the end the T&Ber is dead meat.
[This message has been edited by gatt (edited 07-27-2000).]
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Andy,
I really like the E-diagram!
What do we have to give the guy to run one up for each of the major combatants?
I'm assuming that is based on RL data and not just and example. Is the necessary data available for other planes?
Anyway, thx. That is a nice tool.
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Toad,
these are AirWarrior diagrams.
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Gatt,
Are they based on in-game performance or is it RL based?
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AFAIK, they are based on in-game performances. I've e-mailed Badboy some times ago and he kindly sent me the diagrams about 109F and SpitV performances. Would be great to have the same data and analysis for AH a/c.
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Andy,
Nice diagram. I have a similer e-mail friend who often post on these boards who has done an excel spreadsheet to calculate
1.Prop effic.
2.Climb and best angle of climb
3.Accelleration
4.Max sustained turn rate
5.Cdi, induced drag
6.Cdo, Zero lift drag
7.Cd, total drag
8.Top Speed
This info depends on
1.Aspect ratio
2.Weight
3.HP
4.Air density at alt.
5.Wing Area
6.Prop diameter
7.Stall speed
It is an excellent piece of work. Based on this the Max sustained turn is at a much higher speed than your friends graph. I believe that it is too low because even though your friend is close on the 1g stall of a P-51 in the clean condition he is off on the 3G turn being at less than 150MPH. The Mustangs 3G stall based on the 1g stall is 181.86MPH or 105MPH*1.73(The square of the G factor). The 105MPH stall is from the P-51 Flight manual. In any case the graph is beautiful. I will get my Physics tutor to check the thread and give his two cents.
Maveric,
Thanks for the Link. I will read it tonight.
I would never turn it into a flame war, it's not my style
Thanks
F4UDOA
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F4UDOA
Glad you liked the graph. I did not intend that it be used as an example of specific performance values, but instead as an example of how energy values can be displayed in a manner that a pilot can use.
With regard to the actual graph numbers versus your numbers...in my P-51 handbook, the stall speeds are given in IAS. This chart is TAS. That may well account for the difference.
The HTC folks must have used some baseline for their performance programming. I'd like to see a set of these charts built with those specs in mind.
Andy
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Hmmmm...
you guys are worse than the Virtual Airshow freaks.
GO HAVE SOME SEX GUYS!!! Don't matter what with... sheep - goats- small furry rodents - fatty's mom... JUST DO IT.
-vlkn- in
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Hi,
I would like to address the points made by F4UDOA.
Originally posted by F4UDOA:
Andy,
It is an excellent piece of work. Based on this the Max sustained turn is at a much higher speed than your friends graph. I believe that it is too low because even though your friend is close on the 1g stall of a P-51 in the clean condition he is off on the 3G turn being at less than 150MPH. The Mustangs 3G stall based on the 1g stall is 181.86MPH or 105MPH*1.73(The square of the G factor). The 105MPH stall is from the P-51 Flight manual. In any case the graph is beautiful. I will get my Physics tutor to check the thread and give his two cents.
F4UDOA
The diagram posted was for the P-51D as modelled in Air Warrior. What it shows, is exactly what happens in that simulation, as such it is valuable to the good folk who fly that sim'. However, while it is a 100% faithful indication of what happens in that simulation, in that configuration, the information is non-transferable. It can't be used for other simulations, or for the real world aircraft, although it could be with some adjustments. So, the lift curve used to generate that diagram doesn't reflect the lift curve of the real P-51D it matches the curve used to model the P-51D in Air Warrior. Also, the prop efficiency curves don't match those of the real P-51, and the engine power curves don't match either. For example, the value of Clmax reflected in the Air Warrior simulation (that is the highest point on their lift curve) is 1.56, the value for the real P-51D is 1.89. I believe the difference is due to the fact that the guys at Kesmai probably used airfoil data, which is almost always somewhat less than the values realised by the complete aircraft in flight.
Regarding stall speeds, much care is needed when quoting specific values. For example, the weight of the P-51D could vary from a maximum take off weight close to 12,000lbs to as little as 7,300lbs when landing on fumes with no fuel and a hungry pilot. That results in a stall speed at sea level and standard atmospheric conditions ranging between 70kts (81mph) and 90kts (105mph) which probably explains why the P-51 flight manual quotes the high end value. Following that reasoning through yields 3g stall speeds ranging from 121kts (140mph) to 156kts (182mph)… The point is that the diagram posted is correct for the configuration it represents, just as your figures are also correct.
Hope that helps?
Badboy
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Hi Andy
Originally posted by Andy Bush:
F4UDOA
The HTC folks must have used some baseline for their performance programming. I'd like to see a set of these charts built with those specs in mind.
Andy
Perhaps it's time I did an Energy Maneuverability analysis for the aircraft in AH, if only there was a big enough following to justify a strategy guide type publication <g>.
Badboy
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"Perhaps it's time I did an Energy Maneuverability analysis for the aircraft in AH, if only there was a big enough following to justify a strategy guide type publication <g>."
What a great idea Badboy! And Andy can write the lessons ...
I'm following!! (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
Andy, thanks for the commentary, I find your explanation 'sticks' in my head better than reading graphs, at which I'm lousy.
BTW, great thread F4UDOA, despite that I only understand a fraction of what I read on this type of thread.
Cheers
Yosus
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'One day, flight simulation will be so realistic, that you'll need to wear brown corduroy'
Phoenix Squadron.
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Badz, I feel you would find a larger, more enthusiastic audience eager for your outstanding work here. Nothing wrong with the AW community mind you but there is less appreciation for your PDF files and charts 'over there' than they are due. Talk of WWII aircraft and aeronautics is scant and rare at best to be honest.
-Westy
(Was there ever a consensus reached on the flaming issue of boy scouts and UFO's? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif) )
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Yosus
What a great idea!
In fact, Badboy and I have been writing partners for some time now. We've tried a thousand ways to get a 'how to' book for flight sims written but have yet to find a commercially successful means. No publisher to date wants any part of such a book.
Until then, Leon and I will continue to provide whatever we can here on the forums and web sites such as SimHQ.
BTW...the fourth article in my BnZ series is just about done. I use AH for many of the illustrations. This final BnZ article will suggest a way of flying a 2v1 in our sims and will cover formations, attack geometry and communication techniques.
Andy
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BadBoy,
I didn't realize that the chart was based on AW performance numbers until I reviewed the thread. But I do think the Max Cl of the P-51 is a little high at 1.89. I learned from Wells on these boards that most Max Cl of WW2 fighters fall between 1.4 and 1.5 with no flaps. It turn out to be true with few exceptions. If you reference the NACA report on Lift Coefficients you can find Cl of most major fighter types with and without flaps.
Here is the NACA report Link.
http://naca.larc.nasa.gov/reports/1945/naca-report-829/ (http://naca.larc.nasa.gov/reports/1945/naca-report-829/)
Turns out 1.89 is 50degree flap deflection on P-51. 1.88 is 50degree flap on F4U which was reduced from 2.33 after an addition of a spoiler strip on the port wing to reduce an unsymetrical stall. Hope this is helpfull.
BTW, any new charts or graphs related to actual flight numbers or AH would be appreciated. Great work!
Later F4UDOA
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I've been on both sides of turning parity and seen actual proof that each plane is different.
try to out turn an fw190 in the lightest of p47s and you will die a fiery death in a few turns.
turn a P-38 with a spit9 and you can hang on if your lucky for a while but try it in a p38 vs a spit 5 and they will turn rings around you.
turn a p51 or 109g10 in a flat turn vs an f4u and the f4u will tear you up.
ok done rambling
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Citiabria,
I don't disagree about any of what you have said. Funny thing that I fly the F4U so much that it took me a while to make this observation. No matter what A/C is in front of me they cannot escape by means of a flat turn at sea level. I will eventually get into firing position and blast them. I have not tried the Zero or Spit V in this regard because I thought it would be suicide so I chose not to try. Then I also noticed no matter what A/C was behind me that I could not escape by means of flat turning at sea level. Even with a P-47D30 on my tail(I have this filmed) I could not gain even 1/2 turn until he killed me. I think the reality is that there is such a great parity amoung turning performances of A/C that whom ever is on the offensive will eventually come into firing position unless the other pilot just plain makes a horrible mistake or reverses direction. Even when fighting the
P-47D30 I watched as he stalled and did a semi roll in the opposite direction before regaining control and continuing to gain on me while turning in my F4U low fuel and 20degree's of flap at the edge of a stall.
Pyro made the statement that he would review turning abilities for version 1.04. I think it is odd that the latest A/C modeled, P-47 and FW190A5 seem to turn as well as the best of AH. These are two A/C that were known to have poor turn radius and high stall speeds. I wonder if they were modeled differently than the previous models. Until 1.04 I will be patient. It is limited however to the type of ACM you can employ and expect to live.
Thanks
F4UDOA
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The attacker almost always has a speed advantage, being able to close into firing range. Alot of the time, that advantage, even if it's only 20 mph can make up any discrepency in the rate of turn. With the low G tolerance, the turning 'envelope' is even lower than in some other sims, such as Warbirds, so it's hard to really use a speed advantage for the purpose of gaining angles. Just increasing the G tolerance to 7 or so would make up for alot, methinks.
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f4udoa
your turning to soon and the attacker is getting a snapshot. if you get them close enough on your 6 w/o getting killed you can pull a max G turn and keep turning as fast as you can and you will out turn them and bleed their e to nothing if they follow you.
the trick is getting in the same plane as the enemy because if they go vertical like they can yoyo down and kill you easy
next time you see me online we go to ta and see if f4u can out turn p47 and how quickly it will (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Originally posted by Westy:
Badz, I feel you would find a larger, more enthusiastic audience eager for your outstanding work here. Nothing wrong with the AW community mind you but there is less appreciation for your PDF files and charts 'over there' than they are due. Talk of WWII aircraft and aeronautics is scant and rare at best to be honest.
-Westy
(Was there ever a consensus reached on the flaming issue of boy scouts and UFO's? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif) )
Since Andy pointed me in this direction, I think I'll hang out here and test that theory (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
As for the UFO threads, I never wasted my time on them (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Badboy
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Originally posted by F4UDOA:
BadBoy,
If you reference the NACA report on Lift Coefficients you can find Cl of most major fighter types with and without flaps.
BTW, any new charts or graphs related to actual flight numbers or AH would be appreciated. Great work!
Later F4UDOA
F4UDOA
Thank you for the link to that NACA report, I hadn't seen it before. I've just finished reading and grading my own student's research papers and thought I couldn't face another single report this year, but I was mistaken, it made an interesting change from the Sunday morning newspapers <g>.
I assume you posted the link because you believe that the report supports your contention for lower values of Clmax than those quoted earlier in the thread, I don't agree that the report does that. What that report does do very well, is to show how various design features influence the value of Clmax, which is invaluable if you want to design, or improve an aircraft. What it doesn't do well, is to relate their test results to actual flight conditions. The report concludes by saying that they lacked the data required to estimate the contribution of several important factors to the lift coefficient. They also show a pair of curves that indicate lift coefficients as much as 35% higher under true flight conditions as opposed to their tests. They also openly claim to have made only "rough approximations" in accounting for the discrepancies. Lastly, they make absolutely no mention of other factors that I believe are important, and can significantly increase the lift, which means that while the report represents an excellent piece of work for its intended purpose, it has little value for performance prediction. The values I quoted come from USAAF flight test data and generally show maximum lift coefficients somewhat higher than airfoil data quoted in other sources. This is often the case because in flight there are factors that act to increase the lift and reduce the stall speeds beyond the values obtained in wind tunnel tests.
Having said that, I generally prefer to let the simulation developers worry about matching the performance of the aircraft they model to their real world counterparts. I prefer to confine my efforts to revealing the performance of the aircraft as they are modelled in the simulation, after all, that is what really counts when you fly online. I'm going to prepare an analysis for some of my favourites first, the P-51, the Spitfire and P-38 are very high on the list. In fact I have already done an EM diagram overlay for the AH and AW P-51D, but I'm surprised with the results and I need to discuss it with others before going public.
Badboy
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"In fact I have already done an EM diagram overlay for the AH and AW P-51D, but I'm surprised with the results and I need to discuss it with others before going public."
Was this the one you posted a couple of months ago on the AW 'BigWeek' ng or a new one altogether?
-Westy
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Originally posted by F4UDOA:
Gents,
Is their some kind of design parity amoung the fighter A/C in AH that prevent one A/C from gaining an edge on the other. In combat evaluations of all of these A/C, one of the critical factors in all test was turning ability and minimal turn radius. It was very important in both offense an defense. As it was important for the pilots to be aware of just what A/C they were opposing. This is does not seem to be a factor in AH either by design or not.
I have just checked that for the Aces High P-51D and the Spitfire Mk IX and there does not appear to be a significant disparity for these two aircraft. I have attempted to attach an image below... hope it works (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
(http://www.netcomuk.co.uk/~badboy/PDF/SpitvP51.gif
)
Badboy
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Originally posted by Westy:
Was this the one you posted a couple of months ago on the AW 'BigWeek' ng or a new one altogether?
-Westy
A new one. I haven't done anything for Aces High before.
Badboy
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Originally posted by Badboy:
That should read:
"There does appear to be"
Sorry that the image didn't get attached, what did I do wrong?
I have just checked that for the Aces High P-51D and the Spitfire Mk IX and there does not appear to be a significant disparity for these two aircraft. I have attempted to attach an image below... hope it works (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Badboy
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CC. I remember one where you showed AH's P-56-D was off by 5mph at 18k or some alt. No big deal, that's not why I mention it. Only that you showed AH and AW were the closest out of all the sims that you'd looked at top the real numbers. I should sell my memory while I could get some pennies for it.
(http://www.netcomuk.co.uk/~badboy/PDF/SpitvP51.gif)
I did a cut&paste on the url for your chart and it worked for me. Not sure why it did not for you, but there it is. Anyway,,,, What does the graph show? It appears to me the Spit can handily and easily out turn the 51 but that's why I ask as you say it's not very disparaging and I'm not sure if I'm looking at this right or not.
-Westy
[This message has been edited by Westy (edited 07-31-2000).]
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Good info (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Now here is something real strange I tried today.
Took a B-17 with 25% fuel, at 3000 FT and 250 MPH I could do a perfect loop no problem and allmost complete a second one. After the second loop I went into a barrel roll, this was not so easy but I was able to do it none the less.
Now, I tried this in WB and and at the top of the first loop she fell wing over and wouldn`t let me complete the loop. As far as the barrel roll goes forget it. Halfway into the roll it headed for the earth, compress quickly on her side and I could not recover.
Should you be able to perform acrobatic manuvers in a real B-17?
Potential customer want`s to know.
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Mavric ~ X.O.
WB 325th FG
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I can do the aerobatics you describe in both sims with no major difficulty.
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Funked, didn`t you once say that in WB you could do a loop in WB in a fully loaded P-38 right after take-off and called it BS?
(I never tried it, will test it tonight)
Well that B-17 doing those manuvers seems like BS to me.
Quote:
"I can do the aerobatics you describe in both sims with no major difficulty."
Although I don`t doubt your word, I am a experenced WB flyer and if you can do it I should have no problem doing it either. But I can`t. It happened as I decribed above.
Maybe you could show me in person? A perfect B-17 loop in WB keeping the wings straight and not dipping over that is. And a smooth complete barrel roll would be nice also.
Look forward to it. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Mavric ~ X.O.
WB 325th FG
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Andy,
Wow, that's a great graph. Will you be expanding that to include all the major types in AH? I hope you are basing your information on actual flight test data and not AH data. If you don't mind sharing some trade secret could you please post the calculation you used to arrive at that result. I have been doing some of my own calc's and I want to make sure I am using all of the same factors you are. Although it sure looks accurate to me.
BadBoy,
I have always thought the actual performance of the A/C would exceed the flight tunnel test because of addition lift from the body, tail surfaces, and propwash over the wings. However in the case of the Max cl for P-51 I still don't think it is much over 1.5 in a clean config. If you solve for the Max CL based on a 106MPH stall (That comes from the flight manual not AH) the Max Cl is 1.44 based on
Cl = Lift * 391/(V^2 * Area)
Cl=9700LBS*391/(106MPH^2*233.19)
Cl=3792700/2620122.8
Cl=1.4475
Which is generous because 9700LBS is heavy in a P-51D. However keep in mind that I am a newbie to Aerodynamics so if there is something I am missing I would luv to know.
Also it is my understanding that P-47 clean stall is 115Mph, FW190A5 is almost 110Mph and the F4U is at 100Mph. Is this the same data your working with? What do your tables show for these A/C relative to each other in turning ability? How do you feel they are represented in the Simm?
Thanks
F4UDOA
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With the low G tolerance, the turning 'envelope' is even lower than in some other sims, such as Warbirds, so it's hard to really use a speed advantage for the purpose of gaining angles. Just increasing the G tolerance to 7 or so would make up for alot, methinks.
I agree. 5G (about) is too low for instant blackout. Maybe in constant and prolonged turn but not in a short period.
I think it would be bit more realistic to have blackout at 5G but after short delay. You could pull hard G's for a short time (maybe 5 secons or so, depended on G load) and then blackout if you continue the hard turn.
Low G tolerance might be one thing that makes some people to see AH as "slow" game. Now you really need to do turns with HUGE radius because you cant pull more than 5G's without blacking out.
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jochen
Jagdflieger JG 2 'Richthofen' Aces High
Geschwaderkommodore (on leave) Jagdgeschwader 2 'Richthofen' (http://personal.inet.fi/cool/jan.nousiainen/JG2) Warbirds
T-34/76 to Aces High!
Ladysmith wants you forthwith to come to her relief
Burn your briefs you leave for France tonight
Carefully cut the straps of the booby-traps and set the captives free
But don't shoot 'til you see her big blue eyes
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F4UDOA
I hope we can get some energy diagrams for AH...it would really help the folks 'see' the relative performances of various aircraft...but I'm not the one to do it! The diagrams I've used have all been done by Badboy.
He and I are studying the AH aircraft, and so far we've been somewhat surprised at the disparities we've found. Before we say anything, we need to verify our numbers and make sure we are comparing 'apples to apples' and not something else.
I really like AH...and I want to avoid any impression of being critical of this sim. The overall superior 'fun' factor of AH overrides any technical discrepancies as far as I'm concerned.
Leon and I will keep working this and will publish diagrams when we are confident of their validity.
Andy
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Rgr That Andy,
I can't keep track of who's doing what as far as the diagrams so my apologies to BadBoy. Anyway I am looking forward to seeing what you have comeup as well as many other people I am sure. Good luck getting everything together.
Also in AHT there is a reference to the tolerance of G force by WW2 pilots. I will look it up but it gives almost 30 seconds at 5 g's before blackout. This is from a USARMY document I think.
Later
F4UDOA
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"I really like AH...and I want to avoid any impression of being critical of this sim."
We need more people like you, who question things (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Regards.
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AH : Maniac
WB : -nr-1-
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Mavric I'll go practice, it's been a while since I flew a bomber in WB. But I did a barrell roll at the 99 Con with 6 gunners aboard in the Buff Duel. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Just did a couple of loops and some barrel rolls in the B-17 in both sims, at 25% fuel, 5000 feet. You have to dive a little to do a loop, and I lost about 1500 feet after 2 loops in both sims.
In AH you are limited by stall, in WB you are limited by the reduced elevator response that HotSeat put in when the B-24 was released.
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Originally posted by F4UDOA:
BadBoy,
I have always thought the actual performance of the A/C would exceed the flight tunnel test because of addition lift from the body, tail surfaces, and propwash over the wings. However in the case of the Max cl for P-51 I still don't think it is much over 1.5 in a clean config. If you solve for the Max CL based on a 106MPH stall (That comes from the flight manual not AH) the Max Cl is 1.44
Which is generous because 9700LBS is heavy in a P-51D.
F4UDOA
Your calculations look fine, but they do neglect some important factors, also I disagree with your assessment of the weight. The P-51A had a maximum take off weight of 10,600lbs and the P-51D had a maximum take off weight of 12,100lbs. If you rework the calculations for the P-51D with a 106mph stall speed just after take off, your calculations require a Cl = 1.8.
Also, you can't consider any aditional lift from the "tail surfaces" because in a stable configuration the tail will be detracting from the radial g. But the P-51D wasn't always stable, as I'll explain later. However, one significant factor that was also neglected in the research paper you referenced earlier is the contribution of prop thrust to the radial g. As an example, consider a P-51D flying close to the 1g stall speed, at an AoA close to 18 degrees, the prop thrust will be contributing to the radial g enough to increase the apparent coefficient of lift from 1.44 to 1.6. During a flight test in which an aircraft apparently achieved a lift coefficent of 1.89 (USAAF data) the actual lift being generated aerodynamically would have been closer to a Cl of 1.7 with the component of prop thrust subtracted. That would still include the contribution from the fuselage and the effect of the prop wash energising the boundary layer, which when ignored (during wind tunnel tests on the airfoil for example) yields results much closer to the values that you are comfortable with.
As for the tail force mentioned earlier, during low speed high AoA, the engine thrust contributes to the radial g. At high AoA this can enhance the lift significantly and another benefit of this is that because normally the centre of lift and centre of gravity are relatively close together, with positive stability that requires a downward force on the tail, however, the component of prop thrust, with its large lever arm provides a strong nose up pitching moment that reduces the downward tail force, thus enhancing the lift even further. However, the Merlin powered versions, including the D we have in Aces High, were not so easy to analyse. During a turning engagement these aircraft could become unstable which could mean a stick force reversal, requiring the pilot to push forward on the stick in order to prevent the turn from tightening. This was only a problem with high fuel levels in the fuselage tank because that shifted the centre of gravity backwards creating a very small stability margin. That alone was not so much of a problem on its own, but the centre of pressure also moves forward considerably as the AoA increases until the aircraft became longitudinally unstable. In that situation the pilot needed to apply a push force to the stick in order to prevent further increase in AoA and the eventual stall. That reduction, (or in extreme cases, reversal) of the tail force would enhance the lift even further. My own calculations consider the contribution of all the factors previously mentioned, including prop thrust and longitudinal stability as described above.
As a point of interest, the USAAF data for the P-38L is for a maximum lift coefficient with out flaps of 2.17 and that can be explained because of its twin engine configuration. The P-38 generates even more lift than expected, due to the twin engines for two reasons. Firstly, during low speed high AoA, the engine thrust contributes to the radial load factor twice as much as the single engine fighters. Another benefit of this is the reduction in downward tail force, thus enhancing the lift even further. Secondly, and more importantly, the wings are in the slipstream of the propellers and the wash speeds up and energises the air over them, which significantly increases the lift and reduces the stall speed. Unlike the single engine fighters, this does not result in asymmetrical lift because of the counter rotation, so that also reduces the tendency to spin. All of these factors result in an actual coefficient of lift much greater than the average flight sim pilot, or for that matter, your average aero graduate would normally expect. Add to that, the fact that the unusually high aspect ratio wing gave the P-38 enhanced climb rate and sustained turning ability, all of which is often ignored in flight sim'modelling. For the real P-38, that means that in a clean configuration with flaps deployed, it could turn at VERY low speed, shuddering on the edge of stall, but would not snap into a spin (unless mishandled) because unlike the single engined fighters its counter rotating engines had no net torque and no asymmetrical lift. That meant that if a good pilot stalled in a tight turn, the P-38 would just mush outwards, and that could be recovered with forward stick and no loss of altitude. A good pilot could rack the P-38 around in and out of stall to safely effect a very tight turn, and get the best advantage from that high maximum coefficient of lift <g>.
Originally posted by F4UDOA:
Also it is my understanding that P-47 clean stall is 115Mph, FW190A5 is almost 110Mph and the F4U is at 100Mph. Is this the same data your working with? What do your tables show for these A/C relative to each other in turning ability? How do you feel they are represented in the Simm?
Andy only pointed me to AH a few days ago. I'm investigating those very questions and I promise to keep you up to date on my thinking.
Badboy
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Originally posted by Westy:
I remember one where you showed AH's P-56-D was off by 5mph at 18k or some alt. No big deal, that's not why I mention it.
Ahhh, I remember now. That wasn't an EM diagram, just a speed comparison and the data wasn't all my own (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Originally posted by Westy:
Anyway,,,, What does the graph show? It appears to me the Spit can handily and easily out turn the 51 but that's why I ask as you say it's not very disparaging and I'm not sure if I'm looking at this right or not.
-Westy
You can see from this diagram that the difference in turn rate is not as significant as the difference in turn radius. Notice how the Spitfire is only slightly farther around its circle than the P-51. However, notice how much smaller the Spitfire's turn circle is. The Spitfire can out turn the P-51, but it can turn inside it even more dramatically. This diagram only shows the situation when both fighters are at their maximum sustained turn rates in sustained level turns. At higher speeds, the advantage may swap hands and I can only determine that from an EM diagram overly, and that's on the way (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Badboy
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Badboy,
Your friend Andy just posted the same Doc I have on stall speeds.
(http://www.doitnow.com/~alfakilo/P51stall.jpg)
The stall for the P-51D looks like 10,000lbs at 106MPH max Cl of 1.49.
Anyway that is the Doc I was looking for.
I'm curious as to where you got the P-38 and P-51 3G stall numbers. Was it the Report of Joint Fighters or America's Hundred Thousand?
I know the author of both of those books,
Frances Dean. He is a neighbor of mine and has let me visit his house and research. The numbers for stall speeds and conditions of the aircraft are a little touchy because of who translated the text. It can be a little vague as to MPH and Knots as flaps or no flaps.
He has given me some documents I have scanned regarding flight test of the P-51B vs the F4U-1(modified) and F4U-1A(In service condition) as well as the F6F-3 and F4U-1D vs the FW190A5. Here is the link if you are interested.
http:// [url=http://members.home.net/markw4/FW190_F4U.html]http://members.home.net/markw4/FW190_F4U.html[/url][/url]
http://members.home.net/markw4/index2.html (http://members.home.net/markw4/index2.html)
Hope this helps.
Later
F4UDOA
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DOA,
That formula elimates density (for simplicity), so it's only good if you use Indicated speed and not True speed.
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Originally posted by F4UDOA:
Your friend Andy just posted the same Doc I have on stall speeds. The stall for the P-51D looks like 10,000lbs at 106MPH max Cl of 1.49. Anyway that is the Doc I was looking for.
Yep, that figure can be found with more of the manual at:
http://www.icon.co.za/~pauljnr/manual.htm (http://www.icon.co.za/~pauljnr/manual.htm)
However, while that is based on flight tests, they do appear to have been done power off. As such, the figures won't include any of the effects we have been discussing and that's why I originally dismissed that manual as valid only for the purpose for which it was intended. I assume that was primarily the safety of pilots converting to the P-51. I also suspect that they were done power off for that very reason, to provide reliable stall figures for emergency power off landings and, I believe that it was normal to allow a small safety margin in the figures also. If you consider the stall speed from your figure for the 8,000lbs configuration you get a Cl = 1.52 and adding in the contribution of prop thrust to the lift at that speed brings the effective Cl back to 1.7. Then adding the other effects, including propwash energising the boundary layer, the increase in lift due to changes in the stability, and we are right back where we started.
Originally posted by F4UDOA:
The numbers for stall speeds and conditions of the aircraft are a little touchy because of who translated the text. It can be a little vague as to MPH and Knots as flaps or no flaps.
Yep, and that raises some interesting issues, but that's another story.
Originally posted by F4UDOA:
Here is the link if you are interested.
Hope this helps.
Many thanks... I haven't seen that before, I'll enjoy reading it.
Badboy
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Badboy, the Cl doesn't really increase. It's the apparent velocity that increases because of propwash to increase the lift. That can be misleading when it comes to the induced drag calculations that are based on Cl values.
For example: Cl = 1.5 at 100 mph and 1.7 @ 94 mph might be the same as far as lift capacity is concerned, but when you go to do the induced drag calculations, they will not be the same.
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Badboy,
Yup,
The lift coefficient varies with power settings although I'm still not sure where you get the 1.72. The weight in the equation I posted was for 10,000lbs not 8,000 giving me 1.49. Anyway I know the increase of power adds airflow over the wings increasing Max Cl. I just wanted to show the data without the benifit of power to show just the lifting wing and body. If I do the cacl for Cl at 8,000lbs the Cl is much lower albeit with no power.
8,000lbs*391/(94Mph^2*233.19Wing Area)
3128000/(8836*233.19)
3128000/2060466.8
=1.518 No flaps (The calc doesn't work with flaps because it increases wing area and I don't know what to add to 233.19 to make that an accurate number)
By contrast look at the same data for the F4U-1D Corsair. Stall speeds IAS
Weight 11,300LBS
Stall No power Clean(No Flaps)100MPH
Max Cl=1.407
Stall Power Clean 96MPH
Max Cl=1.526
Stall No Power Full Flap(50Degrees)86MPH
Stall Power Full Flap 76MPH
Have you ever flown a F4U-1D in AH at Full Flap at 76MPH? It falls like a brick. The Mustang also stalls too high. But that's why these charts are important for comparison to real life numbers.
Wells,
You mentioned IAS not TAS for the equations. That's true however there is an Airspeed correction chart in the F4U manual that shows TAS to be roughly equal to IAS with the greatest difference being 3Knots high at 70knts IAS and 8knots low at 300KNTS IAS.
This would seem to work in favor of the A/C and not far off enough to affect the Max Cl.
Later
F4UDOA
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Originally posted by wells:
Badboy, the Cl doesn't really increase. It's the apparent velocity that increases because of propwash to increase the lift. That can be misleading when it comes to the induced drag calculations that are based on Cl values.
For example: Cl = 1.5 at 100 mph and 1.7 @ 94 mph might be the same as far as lift capacity is concerned, but when you go to do the induced drag calculations, they will not be the same.
Agreed.
Badboy
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Now I'm confused?? (http://bbs.hitechcreations.com/smf/Smileys/default/confused.gif)
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First of all... Well... rrrr, uummmm.
Nevermind.
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jehu
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Originally posted by F4UDOA:
The lift coefficient varies with power settings
Not really, it just appears to if you lump together all the contributions to the lift, and then calculate a new Cl based on that. As already pointed out, you can't use that value of Cl in the induced drag calcs, and I only do it for a general impression of the overal lift producing capability.
Originally posted by F4UDOA:
although I'm still not sure where you get the 1.72. The weight in the equation I posted was for 10,000lbs not 8,000 giving me 1.49.
Yep, but take the figures two places below that give 8000lbs and 94mph, the Cl clocks out at 1.52. Then calculate the component of prop thrust at that speed normal to the velocity vector, add that to the lift and recalculate a new Cl, it clocks out just over 1.7, but for that you need the curves for the engine power and the prop efficiency.
Originally posted by F4UDOA:
If I do the cacl for Cl at 8,000lbs the Cl is much lower albeit with no power.
Agreed, but I prefer to include everything I can in my model, because I've found that the little things all add up. However the performance comparison of real aircraft of that time was very unscientific, and I'm afraid we (I'm more guilty than most) are now verging on the anal retentive... Men whose lives depended on this stuff, didn't labor the point this much (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Originally posted by F4UDOA:
Have you ever flown a F4U-1D in AH at Full Flap at 76MPH? It falls like a brick. The Mustang also stalls too high. But that's why these charts are important for comparison to real life numbers.
Nope, (bows head in shame) I haven't flown the F4U at all yet. But I will analyse its performance in AH and provide an EM diagram for it. That will show EXACTLY how it performs in AH, and how it compares with the other AH aircraft, but only that. While I can absolutely guarantee that my EM diagrams will reflect the in-sim' aircraft performance, I'm normally reluctant to make any such claims about my real world aircraft analysis. Now if we could get Andy to put some of the real warbirds through their paces after I had fully fitted them with flight test instrumentation, we might have a
chance... Anyone here own a warbird we can play with? (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
Badboy
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DOA,
Look at your lift equation. It contains the CL and Velocity, right? When you have 'power on', the velocity increases, not the CL. However, when you calculate the new CL based on the new 'indicated' stall speed (lower), it will seem higher because the pitot tube is outside the prop flow and doesn't show the increase in velocity over the wings. Now, if you were to base your Cdi calcs on that new CL, you'd get too much induced drag.
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Hi badz about time you got here. It will be a pleasure to kill you hee too (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
EYE
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Originally posted by eye:
Hi badz about time you got here.
Hiya, nice to see you, do you fly here exclusively now? I'm very impressed with what I've seen so far, fun days ahead!
Originally posted by eye:
It will be a pleasure to kill you hee too (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Only if you have improved a lot (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
Badboy
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Yep this is my home now. Ive sort of missed you bud (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif) Honest.
If you give this a try come on over to rook land. I fly for the airwarriors. It would be fun to fly a few together.
Its a great game just to much coin lol.
EYE