Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Ardy123 on March 04, 2010, 05:49:44 PM
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according to wikipedia the P51 has a lighter wing loading. One would expect it to be able to out turn the 109 then. Are the coefficient of lift that drastically different?
wikipedia 109 g6: 40lb/ft http://en.wikipedia.org/wiki/Messerschmitt_Bf_109 (http://en.wikipedia.org/wiki/Messerschmitt_Bf_109)
wikipedia p51 D: 39lb/ft http://en.wikipedia.org/wiki/P-51_Mustang (http://en.wikipedia.org/wiki/P-51_Mustang)
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My guess would be that the laminar flow wing on the P-51 does not perform as well at low speed as the 109's wing.
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I think thats the case, because the laminar flow wing provides less lift, while producing less drag as well, which is one of the reasons the 51 is one of the faster planes.
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1. Wingloading isn't everything when it comes to sustained turn performance.
2. I'd be curious to see how those "loaded" weights broke down. More typical for a P-51 to weigh in excess of 10,000 at a moderate fuel load, which pushes its wingloading back up in the 42 range vice 39. I'm curious as to whether or not that's a heavy weight for a 109G6.
3. Laminar flow airfoils at normal, cruise Reynolds numbers, are actually quite high lift airfoils--some of the highest actually. They will be THE highest lift/drag ratio airfoils at their design lift coefficient. They do generally have poorer performance at lower R numbers though, and certainly have higher drag coefficients when they are operated only a few degrees AoA away from their design lift coefficient.
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Im not attempting to even think I know what Im talking about as Ive only been playing a year and still have much to learn, but in a turn fight doesn't the 51 have 109 at the higher speeds but after 1-11/2 turns the speed drop off and the 109 gain the upper hand? As I said, this is just what I have heard and seems to happen anytime Im in the 109. I do not use the Pony for turn fighting, mainly just an attack/BnZ aircraft and it serves me very well...I tried to do the turn fight thing last month and compared to the month before, it wasn't good, lol. Good luck and hope you find out what your lookin for.
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I love it when ponies go into sustained engagements in me G-6. :aok
Regarding the numbers, I believe stoney nailed it.
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1. Wingloading isn't everything when it comes to sustained turn performance.
2. I'd be curious to see how those "loaded" weights broke down. More typical for a P-51 to weigh in excess of 10,000 at a moderate fuel load, which pushes its wingloading back up in the 42 range vice 39. I'm curious as to whether or not that's a heavy weight for a 109G6.
3. Laminar flow airfoils at normal, cruise Reynolds numbers, are actually quite high lift airfoils--some of the highest actually. They will be THE highest lift/drag ratio airfoils at their design lift coefficient. They do generally have poorer performance at lower R numbers though, and certainly have higher drag coefficients when they are operated only a few degrees AoA away from their design lift coefficient.
Excellent post.
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Don't remember the exact game weights but that 40lbs/ft is pretty much the figure for G-6's normal take-off weight without any external stores. If I remember correctly G-6's Clmax in clean configuration is about 1.4 with slats out. One thing that will help the G-6 against P-51D in general maneuvering contest is greater amount of excess thrust.
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Planes don't out turn other planes. Pilots do by knowing their planes strengths and
the weaknesses of their opponents aircraft.
But if you're turn fighting at 5k in AH then right off the bat you messed up as you're
attempting to correlate real world physics and encounters with the utter fantasy
world that is the main arena.
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2*WL/rho*Cl*sin(theta) = R (turn radius - sustained)
First, yes, Stoney knows his stuff and doesn't give bum steers. Thank god for that because the last thing this place needs is another bullsh*t thrower. I'm still sick of hearing Thrash ragefully emote (i.e., devoid of fact or reason) against the Spixteen.
Second, the equation above is a simple expression of what drives Radius - Wingloading lives in the denom and high is bad. That's quite clear.
However, this powerloading deal is critical, too, since sin(theta) approaches max as bank angle theta approaches 90. While sustaining a 90 is out of the question, it takes excess power to overcome the increased in lift-dependent drag required as you bank. Thus, as noted in a previous post here, yes, powerloading is also important since it determines your max bank.
I also think Stoney's practical consideration for the P-51's eminently "loadable" airframe (all that range is achieved by a combination of the low drag afforded by the lf wings and airframe design PLUS a whopping fuel load) is also valid - .i.e., you MIGHT see a P-51 at the lower edge of it's WL range but then, monkeys MIGHT also fly from my butt. Generally, people fly with a significant proportion of fuel. They get nervous when it gets low - even if low in a 51 isn't nearly the same as low in a 109.
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Thank god for that because the last thing this place needs is another bullsh*t thrower.
I wasn't trying tho be a 'bullsh*t' thrower or state anything was wrong with the flight model, I was just curious, because of the numbers.
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I wasn't trying tho be a 'bullsh*t' thrower or state anything was wrong with the flight model, I was just curious, because of the numbers.
Excuse me, Ardy. Did someone accuse you of being a roadkill thrower?
I was using this thread as a means of fingering thrash for his unmoored rage at the Spixteen. It has nothing, as far as I know, to do with you.
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Excuse me, Ardy. Did someone accuse you of being a bullsoup thrower?
I was using this thread as a means of fingering thrash for his unmoored rage at the Spixteen. It has nothing, as far as I know, to do with you.
I didn't think you were directly accusing me, but all to often these threads turn into 'the flight model is porked' by certain members, or the flame fests around that kinda nonsense, so I figured I'd set the record straight right off the bat.
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Depending on the weight a good pony stick can give a 109G6 all it can handle....
Of course I fly light and stretch that fuel load like a rubber band. Your right, most people fly way to heavy in both models of the P-51. They also dont cruise at the right altitude, mostly too low and too slow. Way to often I see people start to descend and build up speed. The reality is if your fuel critical the first thing you should do is throttle back to normal power and climb to 12.5k (D) or 17k (B). Once your speed is in the high 300's then go to max cruise...
Surviving a turn fight in a P-51 starts with fuel management, if you fight heavy your dead in this case. Get down below 50% and look for a 109G6 with a little fuel on board. Given equal pilots it should make for interesting fight and 50/50 on the outcome. If the 109 fights uphill the P-51 is in trouble, downhill goes to the Pony.
Above 20k the advantage starts to go to the P-51 regardless....
Strip
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I didn't think you were directly accusing me, but all to often these threads turn into 'the flight model is porked' by certain members, or the flame fests around that kinda nonsense, so I figured I'd set the record straight right off the bat.
Okay. We're on the same side of that.
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if your fuel critical the first thing you should do is throttle back to normal power and climb to 12.5k (D) or 17k (B). Once your speed is in the high 300's then go to max cruise...
A bit of a hijack, but if you're fuel critical, the best thing you can do is accelerate to the speed that gives you best range at your current altitude, and then throttle back to the power/rpm setting that maintains that speed with the lowest fuel consumption. With no tailwinds available in-game, you certainly don't want to climb, as the higher TAS at the higher altitude will not make up for the fuel you burned in the climb, regardless of the climb power setting. This is the reason why Lindbergh flew on the deck the entire way to France. If you have excess altitude, and are fuel critical, the most fuel efficient technique to return home is to immediately establish best glide speed, then cut the engine. Glide at best glide speed until you have no more altitude to trade for speed, and then resume using the power-on, economy technique I described above. Further, if you're flying a long distance, and minimizing fuel consumption is a higher priority than speed, and you have the space to do it, it is always best to fly from point A to point B as close to the deck as is safe, and then only enact your climb at the minimum distance from the objective that allows you to reach your target altitude and/or speed.
If you climb to any altitude in this game, full power (WEP even if available), will be the most efficient climb power setting, since you don't have to worry about engine health. The only time using reduce power in a climb is advisable in AH is when you're trying to keep a formation together as lead. You have to leave your wingmen with excess power to either keep in speed or climb.
I don't have time to post the equations to support these statements, but they're out there if you want to find them.
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To add a bit to what Stoney posted, looking at the manuals I have for the planes in game, (and I have tested this with the F6F and the F4U) once at minimum altitude, use the lowest RPM possible to maintain the glide speed to get the maximum range.
Obviously you need to be clear of any enemies but, lowest RPM/at glide speed/as close to sea level, will give you the best range for the fuel remaining.
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With no tailwinds available in-game, you certainly don't want to climb, as the higher TAS at the higher altitude will not make up for the fuel you burned in the climb, regardless of the climb power setting.
In the case of Brewster in AH, I disagree. AH's Brewster pretty much gives the right cruise speed for cruise settings at 6k, if you are on the deck the cruise speed for the same power setting is over 70mph less!! So darn right it is wise to climb and acceletare to the cruise speed/altitude with full throttle before leveling out! And the cuirse speed at about 6k is about modeled right. Hard to stay if the low speed cruise speed is too low...
...if I made mistakes in my post it's all beer's fault....unfortunately... :cry
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I remember seeing graphs for the P51's airfoil geometry (CL vs AoA) compared with a normal airfoil. The P51's lift coefficient drops off at a lower AoA than the standard airfoil (higher stall speed). It's not just lift-loading, but available lift as well.
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It does no good to cruise on max fuel if you still end up ditching.
The best thing you can do is climb (not to the moon, mind you).
Why?
Because when you DO run out of gas then you can glide for a long distance, banking on that air cushion you built up underneath you.
Scenario 1: You stay low, cruise, eng dies 1 mile from the runway and you ditch.
Scenario 2: You climb, use more gas, eng dies 1 miles from runway, but you can glide her in and dead-stick the landing for a safe return.
You always want some alt under you, even if low on gas. Coming from a guy that makes tons of deadstick (no oil, shot out gas, damaged, etc) landings, it's a life-saver, virtually speaking.
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I remember seeing graphs for the P51's airfoil geometry (CL vs AoA) compared with a normal airfoil. The P51's lift coefficient drops off at a lower AoA than the standard airfoil (higher stall speed). It's not just lift-loading, but available lift as well.
(http://i125.photobucket.com/albums/p61/stonewall74/th_LIFT_DRAG_SL150.jpg) (http://s125.photobucket.com/albums/p61/stonewall74/?action=view¤t=LIFT_DRAG_SL150.jpg)
You can see visually what I was explaining above. This was done from an analysis I did on XFOIL a few years ago. And, to illustrate Boomer's post, this was the lift polar that was plotted for both aircraft. Some of you have probably seen this before. The La-7, from what I've found, used the 23XXX series airfoils. These were plotted using the MAC for both aircraft to determine the Reynolds number at ISA.
(http://i125.photobucket.com/albums/p61/stonewall74/th_Cl_Comparison_SL150MPH.jpg) (http://s125.photobucket.com/albums/p61/stonewall74/?action=view¤t=Cl_Comparison_SL150MPH.jpg)
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In the case of Brewster in AH, I disagree. AH's Brewster pretty much gives the right cruise speed for cruise settings at 6k, if you are on the deck the cruise speed for the same power setting is over 70mph less!! So darn right it is wise to climb and acceletare to the cruise speed/altitude with full throttle before leveling out! And the cuirse speed at about 6k is about modeled right. Hard to stay if the low speed cruise speed is too low...
...if I made mistakes in my post it's all beer's fault....unfortunately... :cry
Low alt cruise speed is what I meant, sorry. It was a rather suprising when I noticed the huge difference, ended up ditching a few times. :)
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If you climb to any altitude in this game, full power (WEP even if available), will be the most efficient climb power setting, since you don't have to worry about engine health. The only time using reduce power in a climb is advisable in AH is when you're trying to keep a formation together as lead. You have to leave your wingmen with excess power to either keep in speed or climb.
I don't have time to post the equations to support these statements, but they're out there if you want to find them.
In game I believe this to be totally false, WEP in a pony is only worth a few hundred feet per minute over normal power yet consumes nearly twice the amount of fuel. If you find me with 50 gallons of fuel and 200 miles to home you certainly wont find me on the deck. You will not find me cutting the engine in and out alternating between climb and descend either. As the P-51 is the only plane that I have thoroughly tested the throttle settings on its the only plane I can comment on. This is probably why I can stretch the P-51's range on par with anyone in the game though.
Strip
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In game I believe this to be totally false...
I won't argue with you or Krusty, but when you test it, I'd be interested in the results. Who knows, maybe I'm wrong?
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In game I believe this to be totally false, WEP in a pony is only worth a few hundred feet per minute over normal power yet consumes nearly twice the amount of fuel.
Hm
On deck, WEP consumes ~360gph, MIL ~300gph.
Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.
With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.
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Lusche,
Just like to point out I said normal power, which is 2700 rpm and 46" of manifold. Try running the level GPH test at 12.5k with the D or 17k with the B with normal power settings. You should get somewhere in the 1.60 to 1.70 range I believe from memory alone.
My computer is down so I cant test this myself or I would post the numbers.....
Strip
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Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.
With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.
Just to add....
Lusche, your test does show me that it is better to use a reduced power setting. You used less fuel to climb the same distance and cover more distance at the same time. I would be interested to see what 2700 rpm and 46" manifold would do in the same test.
We are starting to hijack this thread a bit and I dont want go down that road anymore. If we want to discuss this more perhaps we can start another thread? I am not interested in proving anyone wrong or right but I am curious and perhaps looking to improve upon what I do.
Strip
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Lusche, your test does show me that it is better to use a reduced power setting. You used less fuel to climb the same distance and cover more distance at the same time. I would be interested to see what 2700 rpm and 46" manifold would do in the same test.
Doing it right now. :)
And yes, I completely missed "normal power" in your post. :o
Conducted a little test: Pony D, 50%fuel, FB 2.0. Takeoff to 10k, timer starts to run when starting engine.
With WEP: Time 3:34, fuel consumption 21gal
With MIL: Time 3:54, fuel consumption 19gal.
With normal: Time 5:44, fuel consumption 17gal.