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Aerodynamic refinements do count. The K-4 introduced the more stremlined HMG installation, wheel well covers, and reintroduced retractable tailwheel - all of that accounted for 20+ km/h more than 109Gs with DB 605ASM and 605D engines. The K-4 was upposed to do 710 km/h at 7.5 km with 1565 PS (441 mph at 24600 ft with 1543 HP), that is a ballpark with P-51D that used ~1500 HP to do the same.
True. The fact that the three guns alone still enabled it to be a potent fighter is not in dispute, though. The canoe guns did affect handling and manoeuvrability, however; virtues that the F maintained, but were lost on subsequent variants.
Does the zero lift drag coefficient take into consideration the size of the object (like the wingspan) or is it just like a per meter kind of thing?
Is there a list of the drag coefficients for different aircraft by type?
The 109 had a lot of protrusions, tail wheel and open wheel wells and everything but it was such a small aircraft. That is why it had relatively low drag.
Wasn't until the ultra streamlined P-51 showed up that they arguably needed to focus more on reducing drag further.
The low drag wing of the P51 seems to have lost a little bit and lift because it doesn't turn all that well despite being pretty big, or maybe that's just a factor of weight
Does the zero lift drag coefficient take into consideration the size of the object (like the wingspan) or is it just like a per meter kind of thing?
Hmm, I don't know if 12 mph is such a monumental increase, given the extent of the refinements you mentioned. I'm also wondering if suspected poor quality control negated a lot of the possible performance improvement that these changes could bring. And wasn't that speed only an estimate, as no real-world test data exists for the K series? I'm fully prepared to be wrong about this.
Does the zero lift drag coefficient take into consideration the size of the object (like the wingspan) or is it just like a per meter kind of thing?
Is there a list of the drag coefficients for different aircraft by type?
The 109 had a lot of protrusions, tail wheel and open wheel wells and everything but it was such a small aircraft. That is why it had relatively low drag.
Wasn't until the ultra streamlined P-51 showed up that they arguably needed to focus more on reducing drag further.
The low drag wing of the P51 seems to have lost a little bit and lift because it doesn't turn all that well despite being pretty big, or maybe that's just a factor of weight
but it shows that improvement in streamlinign counts.
Yes. It's a non-dimensional coefficient, so it provides a comparison that removes size differences.
If I remember, the P-51 had a higher wing loading.
Does the zero lift drag coefficient take into consideration the size of the object (like the wingspan) or is it just like a per meter kind of thing?
The drag coefficients for a specific RN (see below) are individual component drag ("force) values observed in the wind tunnel as each individual component is isolated as a change, then divided by wing area. Only Wetted Area calculations are derived as Total Drag/Total surface area.
Is there a list of the drag coefficients for different aircraft by type?
There are for US aircraft in NACA reports for 1940 and 1945. The Brits complied one list that I know of about 1942-1943. I don't have similar documents for USSR, Germany or Japan
The 109 had a lot of protrusions, tail wheel and open wheel wells and everything but it was such a small aircraft. That is why it had relatively low drag.
The wing and radiator/cooling drag components were by far the most significant, but all the other factors combined were important.
Wasn't until the ultra streamlined P-51 showed up that they arguably needed to focus more on reducing drag further.
For a long time, the result of the low drag for the Mustang remained 'unexplained' - but it wasn't laminar flow. There Was some positive value of the shape of the airfoil after wake flow max T/C to trailing edge was scrutinized with trailing edge drag rakes, but the separated flow aft max CP was determined to be a factor of the relatively lower velocity gradient from LE to max T/C relative to say, the NACA 23016. The adverse pressure gradient was less 'malignant' until the flow was past max T/C ---------------> resulted in lower wake area in front of max t/c. This is why the Pressure Drag of the Mustang wing was lower. It is also why it performed so well in high speed dives.
The low drag wing of the P51 seems to have lost a little bit and lift because it doesn't turn all that well despite being pretty big, or maybe that's just a factor of weight
The CL for the Mustang wing and 109 and Fw 190 wing in level flight were all pretty close, but the LE slats for the 109 as stall approached were a definite benefit in medium speed/high G turns. Climb is strictly a function of Power Available - Power Required and Wing Loading. Obviously Drag and Weight are important factors.
I will devote a lot of time in the Apendices of my new book on this very subject:
Start with Power Available vs Power Required as the fundamental set of calculations once the drag parameters are derived (wind tunnel testing);
'The Wing is The Thing' to begin the discussion.
The achievement of (Close to) net zero drag for the internal cooling system is an assumption based on the composers (Horkey and Ashkenas) of the Performance Calculations contained in NA-5534 on the P-51B-1-NA airplane - for high speed Cooling Drag. In this assumption the Pressure and internal friction Drag compared to Thrust generated by the design often referred to as the Meredith Effect is specifically stated as "0 for high speed cruising at Critical Altitude" BUT the Delta CDp for 35,000 feet = .0004 and at 40,000 feet = .0010. In other words Net Zero Internal CDp for only a region at high speed in a narrow altitude envelope.
The Delta CDp for CLIMB condition = .0064 at ALL altitudes independent of Reynold Number.
The INITIAL base CDp for RN =1.8x10^^ for the Wing = .0074 (note: the same initial value for same wing at 2.0x10^^6 for the P-51D wing =.0070). This is a value that considers the profile drag of the wing immersed in a flow - INDEPENDENT of the friction drag.
This value is far below that of the same relative thickness wings of the Fw 190/F6F/F4U/P-47/Bf 109 using NACA 230xx airfoils at same RN.
The second significant base Delta CDp values for comparison, but less than the wing in importance, are the form drag totals for Fuselage, empennage, carb duct, cockpit enclosure build ups. If you wish to ask why, consider that the entire airframe Lines were developed using Descriptive geometry for which the contour from nose through cockpit enclosure was essentially an ascending shape area of low gradient change aft of the card intake duct (including Allison).
(Note that ALL Mustang variants placed the 'disruptor' (scoop, ducting for radiator/oil cooler, intercooler, and exhaust exit) aft of the CP of the wing and aft of the boundary layer separation from fuselage and wing.)
The next significant CDp factor was the Friction Drag Delta CD = .0008 + 'Gap' Drag Delta CD = .0004 = .0012 which is Constant for All RN - a Very low value speaking to the following: 1.) Extremely good production design co-ordinated with factory processes to achieve extremely good sheet butting, flush riveting, excellent jigs and fixture design, priming/sanding/painting of upper and lower wing surfaces through ~ 40% wing chord, and placement of important panels at or aft of that region.
These values for CDp were the very best in comparison with all the values I have seen presented for other aircraft.
Looking to Hoerner 14-4 (b.) Drag of the Wing ------------> the comparable Friction drag for paint irregularities, gaps, bumps, sheet edge and rivet losses @ RN=1.1X10^^7 (For ONLY the wing) ----------> .0035 (skin friction) plus .010 (gap/surface imperfections). Compare to .0008 plus .0004 for the P-51 values above. More than 10x Bf 109G total skin friction and surface imperfection components for the wing drag over P-51B drag.
Hoerner does not present the individual components of parasite drag as a function of RN like NAA. That said, the clues for his Parasite Drag as function of RN @ 4x10^^6 (Wind tunnel at Chalais-Meudon for either Bf 109E or F in 1941) = CDp .030 Without momentum drag of engine air intake of that of the tail wheel.
The comparable CDp for RN=4x10^^6 for the P-51B = .0190 -----------> ~ 63% of the Bf 109E
Comparing CDp for his calculation of .028 @RN=2^^7, the comparable P-51B CDp = .0155 ----------> 55% of the Bf 109E
In Chapter 14 he 'reverse calculated total drag based on T=D;
For his Calculated Total Drag (CDt) at Vmax (= 380mph at 22,000 feet) = 0.036 [includes base parasite/form drag, vortex drag + high speed cooling drag) multiplied by Mach No. correction +Induced drag. For the P-51B, the same CDt = 0.24 ------------> 66% of the Bf 109G
Last note - the High Speed/Low Drag 45-100 wing while loosely described as Laminar (not so much), was extremely low drag in two areas of discussion. First, the low velocity gradient from LE to max T/c at 37.2 % was much lower than equivalent thickness 23016 airfoil which delayed Mach drag rise and major CP shift, and second - the form drag of the wing was simply lower.
I HAVE not spent a lot of time looking at the Hoerner discussion, but the P-51B drag values for CDp and CDp1(combined gun ports, radio mast, gaps/leaks, friction, etc) are extracted from the P-51B Report, compared to P-51D and P-51H to check for unexplainable variances (none other than P-51H had lower wing parasite drag)
Postscript. The Cooling drag build up for climb (worst case) was .0064 for a combination of internal pressure drag/flow losses of the scoop/plenum/oil cooler/radiator/exit plenum and open exit gate. So, if we take Horkey and Ashkenas at their technical competency, then for Net Zero high speed Cooling drag, the CD to be recovered by incremental Meredith Effect jet thrust = .0064. Thus, if Jet THRUST = 0 and all internal drag components are not neutralized, the the total drag build up for RN=2x10^^7 = 0.31 --------> 86% of the Bf 109G-6 calculated total by Hoerner.
Take what you want, leave the rest.
Is there such a thing as a list of parasitic / profile drag for a variety of major fighter types, or is that going to be in the book? When is the book available I'm sold!
What enabled the 109F4 (and less applicable to the F1 and F2) was that big & powerful engine was installed on smalll, light and reasonably well streamlined fighter.
I had read a max speed figure of 727 kmh/452 mph. Anyone knows about this?
That would be a speed value for the K-14, the version powered by DB 605L engine that was outfitted with a 2-stage supercharger.
The source gave it for the K-4 actually.