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No.
In comparing airframes, what is important is the hp used verses airspeed attained. I used this chart because it had a distinct power setting test for the P-51 of about 1150 hp which very close to the Bf-109F hp of 1165. The airspeed of the Spit looks quite small so I am suspect that the hp may be wrong. However, even the much more powerful IX top speed at SL is only about 330, quite a bit lower than the max shown by the chart for the P-51A.
For any given hp and altitude, the P-51 airframe will substantially out perform the other three aircraft in airspeed. The P-51 airframe is the most aerodynamically efficient airframe of any major propeller fighter of WW2. The Fw-190D-9 is a close second.
I'm not that fluent with this, so bear with me
A table from Lednicer's analysis shows Cdswet of the P-51s as being in league of it's own, while the Spit IX and Fw-190D-9 are comparable - meaning D-9 is not that close second?
the 51 out perform in max speed but not in all others performances
taking for good your power
power/weight 51 1150/8000= 0.14 HP for lbs
power/weight 1099F 1165/6400= 0.18 HP for lbs
over 25% advantage for 109F so what planes has best acceleration or best climb?
No.
In comparing airframes, what is important is the hp used verses airspeed attained. I used this chart because it had a distinct power setting test for the P-51 of about 1150 hp which very close to the Bf-109F hp of 1165. The airspeed of the Spit looks quite small so I am suspect that the hp may be wrong. However, even the much more powerful IX top speed at SL is only about 330, quite a bit lower than the max shown by the chart for the P-51A.
For any given hp and altitude, the P-51 airframe will substantially out perform the other three aircraft in airspeed. The P-51 airframe is the most aerodynamically efficient airframe of any major propeller fighter of WW2. The Fw-190D-9 is a close second.
Well, we do know that V-1710-39 (Mustang Mk.I) developed 1150 hp at SL (installed) with boost (Military setting) and we also know V-1710-81 (P51A) developed similar power without boost, but was apparently 30mph faster.Which engines EXACTLY were used in each aircraft and what boost LIMITS were being used.
It may, but usually doesn't, since "aerodynamic efficiency" mainly refers to L/D ratio."aerodynamically efficient airframe" may mean the lowest total drag for it's size.
Mustang was pretty sleek at high speeds.Cola - what do have in mind relative to such low Drag (outside Rutan's wonders) in a reciprocating engine (or turboprop) aircraft that has been designed and flown in production since the P-51B/C/D/K/H?
is misleading.Well, we do know that V-1710-39 (Mustang Mk.I) developed 1150 hp at SL (installed) with boost (Military setting) and we also know V-1710-81 (P51A) developed similar power without boost, but was apparently 30mph faster.
Well, we do know that V-1710-39 (Mustang Mk.I) developed 1150 hp at SL (installed) with boost (Military setting) and we also know V-1710-81 (P51A) developed similar power without boost, but was apparently 30mph faster.
So, you still didn't answer my question, because obviously power was equal and you insisted, that was enough to make comparison.
Were you talking to Dave? Shortround and Tomo pretty well answered this question - If I understood your point?
At the end of the day, while HP is the rule of thumb you still have to reduce both Hp developed at the specific altitude by a.) some efficiency factor (dependent on a lot of stuff but mostly the Prop) with .85 assigned for preliminary factor and then divide by airspeed -------> Thrust. This is where you start for the free body diagram of T=D (as I assume you know)
It may, but usually doesn't, since "aerodynamic efficiency" mainly refers to L/D ratio.
I agree importance of Lift to Drag ratio but not easy thing to get to. L/D is a maximum where Induced Drag and Parasite Drag are in balance and Total Drag is at a minimum. Further the L/D as expressed in Drag Polars is also a function of Reynold's Number and MOST Often presented Only for the airfoil. And the airfoil section Drag polars are usually for an infinite wing - which is where the differences in AR and Tip Ratios will help with calculations for Induced Drag.
P51A had a 5% smaller AR and 10% higher wing loading then 109F4, so the actual amount of drag reduction the Mustang's laminar wing produced in relation to higher alphas flown over almost all speeds, makes your claim very dubious, at best.
I disagree but willing for you to flash an airframe drag polar, or at least the 2R1 Root and Tip Drag Polars so we have a place to start. The P-51A Zero Lift Drag was around ..0165-.0170 depending on racksw/no racks, The 109F as near as I can find has a Zero Lift Drag of .026-.028) as long as the altitude/speed combination is under ~.55M - and both of these ships are just below that.
As max L/D for both of these ships should be at ~ 4-5 degrees AoA ,CDo from my perspective in this discussion is the total of Parasite Drag (friction, objects, gaps, etc) + Profile/Vortex Drag (AoA related as well as interference drag of the wing body) + Compressibility Drag (not a factor with P-51A and 109F4) + Lift Related Drag (induced,washout).
It's probably the other way around, but I wouldn't speculate at this point.
Why not? You must have a notion why you believe the 109F was both 'more efficient wrt L/D' but also why the airframe had the ability to grow in Gross Weight and Mission profile better than the 51?
Mustang was pretty sleek at high speeds.
It was pretty sleek at low and medium speeds also
But as I said, no such thing as "best" airframe in such broad terms.
Airframes that fly good straight, usually suck in turn and the other way around.
There are more than a few direct contradictions to that Statement - Spit IX/XIV or P-51H or F4U or F8F or Ta 152, etc come to mind
All planes are results of a KPP instilled compromises.
It may, but usually doesn't, since "aerodynamic efficiency" mainly refers to L/D ratio.
At the end of the day, while HP is the rule of thumb...
@drgondog,
Now, the P51A's engine characteristic, from Shortround6's chart, looks more like Merlin 45, instead of V-1710-81 a standard engine for P51A and this combination certainly doesn't belong to '41 and comparison against 109F4.
There is no chart for a P-51A w/Merlin of any kind until the Mustang I 'equivalent' airframes that the Brits used as test airframe for the 'to be' P-51B. That was a Merlin 61. The Allison 1710-81 had 1200 hp at TO, 1330 on Military Power at 11,800 (57"hg)and 1125 Hp at Combat/WEP for 14.6 at 38.3 "hg
Then, there's the matter of supercharger tuning and propeller, which differs for those two engines and particularly for 109, so again claiming superior drag performance based on different engine/propeller setup is also misleading.
This is why I said 109G-1 would be better comparison to P51A (with Merlin 45) from the chart.
Why do you refer to the Merlin 45 as part of any chart? If you want to compare a Merlin engine with a P-51A/Mustang I airframe you need to refer to the the experimental data from the RAF. The initial mod was with Merlin 61, the last two were with Merlin 65 and a Jablo (Spit IX) four blade 10-9" prop. If that is your standard for a P-51A airframe (dirtied up with huge front intake) with a 109 of any kind you want to go 109F-4 with 1170 Hp at SL to the P-51 with at 1180 hp
As said, I won't speculate, since assumption is mother of all f*ck-ups.
If you get your hands on measured or manufacturer's data, not computer simulations and time permitting, we can make a thorough analysis and comparison.
So, remove speculation - Kurfürst - Mtt. AG. Datenblatt, Me 109 G - 1. Ausführung should work for you on the F-4 and below for the P-51A w/1710-81
http://www.wwiiaircraftperformance.org/mustang/P-51-A_43-6007_Flight_Tests.pdf
A couple of quick notes. For the flight tests performed on the P-51 (Cannon version) w/1710-39 and max Hp = 1180HP in contrast to F-4 w/DB601E Hp=1170, the P-51 is moving at 363mph to the F-4 at 526km/hr (326mph) that should give a quick sense of respective drag.
The Gross weight comparisions = 286o Kg (6306 plounds) for the F-4 and 8110 pounds for the P51.
Quick summary from the above flight test data - worst case versus Allison 1710-39 equipped airframe = 37mph better dash speed for the 51 at SL, or 11% faster despite a 28% increase in Gross weight between the two, with the lower rated -39.
Thrust = Drag. For the flight tests presented for your pleasure, the -39 and the DB 610E engine performance is the same at SL.. we don't know if the efficiency of the prop is the same, nor the exhaust thrust - but assume .85 and 14% respectively until you can prove otherwise. Hoerner uses 14% of derived Thrust in his textbook derivation of Me 109G Drag analysis, so assume the Allison is no worse or better ?
I agree that friction drag was major player in drag at top speeds, but there are also matters of wetted area, which is higher for Mustang in all speeds (higher alpha and larger size), so for the rest of envelope Mustang wasn't as good lifter, but I won't get into how much.
The larger total wetted area of the 51 makes the compartive drag case even worse for the Me 109F-4. The 51 will have lower total Parasite Drag Coefficient by a large margin as shown below
In the example given above, the Thrust for the 1180HP engines = .85*1180hp*550/(363mph*1.467)= 1036 Pounds of Thrust for the 51. For the F-4 = .85*1170*550/(326*1.467) =1143 pounds. So the F-4 is generating 10% more pure thrust before accounting for exhaust thrust.
51 Total Thrust = 1036* 1.14= 1181 ponds
F-4 Total Thrust =1143*1.14=1303 pounds or 10% more thrust than the 51 at SL. The difference in Total Thrust will increase in favor of the F-4 as altitude increases.
51 Wing Area= 232 sq ft, so dynamic pressuer q=.5*.002376*(363*1.467)>2=336.9 psf
F-4 Wing Area = 172 sq ft, q=.5*.002376*(326*1.467)>>2 = 271.7psf
For Flat plate drag
Total Drag 51 = Cd*q*Wing Area S; D/q=1181/336.9= 3.5 sq feet; Cd=3.5/232=.015 for 51 at SL, 363 mph, 1180 hp
Total Drag F4= Cd*q*Wing Area S; D/q=1303/271.7=4.8 sq ft; Cd=4.8/172=.028 at SL, 326 mph, 1170hp
Cd Wet = 1181/336.9/851sq ft (IIRC from Lednicer) = .0041 for 51 ~ 1/2 of the F-4
Cd Wet = 1303/271.7/590sq feet (from Hoerner Fluid Dnamic Drag=.00813 for F4.
51CDw= 1/2 F-4Cl 51 = (W/S)/q = 8110/232/336.9 =.1037 CDi = (.1024>2)/(3.14*.85*5.9) = .000666
Cl F4 = (6306/172)/271.7 = .1349 Cdi = (.1349>2)/(3.14*.85*6.1)= .0011; NOTE - debatable AR for F-4, should be lower based on b.2/span but I'm using Hoerner's AR for the 109G
Flat plate Induced Di 51 = 232*.000666 =0.155 sq ft --> Parasite Drag = 3.5-.15= 3.345 sq Ft
Flat plate Induced Di F4 = 172*.0011 =0.1892 sq ft---> Parasite Drag = 4.8 -.189 = 4.61 Sq ft
@Shortround6,
look, you said "aerodynamic efficiency" and I told you what does it refer to and it's not Cd/aircraft size...and it doesn't refer to wing only, but the whole aircraft.
See above for CD wet comparison between P51 w/1710-39 and F-4 w DB601E. The 51 has lower induced drag, lower parasite drag, lower total drag by a wide margin - and flies faster at SL with same Hp engine
What you said, Cd/aircraft size is more in line with fineness ratio.