Deleted member 68059
Staff Sergeant
- 1,058
- Dec 28, 2015
It was extremely small and difficult to see though, and did sort of fire back as many pilots were killed by the blast of cannon detonated warheads
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It was extremely small and difficult to see though, and did sort of fire back as many pilots were killed by the blast of cannon detonated warheadsA V1 didnt change direction or fire back.
From what I read apart from the warhead itself the "kill area" on a V1 amounted to the motor itself and the single most telling factor was having cannon not MGs.It was extremely small and difficult to see though, and did sort of fire back as many pilots were killed by the blast of cannon detonated warheads
Thanks for posting that, the corresponding correspondence files have useful letters too>
uumm Laminar flow wing is when the top surface and bottom surface are near identical. thus when compressibility occurs it happens at the same time and at the same distance from the leading edge. as a result there is no compressibility torque imposed on the wing.Laminar-flow is not the same as "thin". A laminar-flow wing has the thickest part of the wing positioned along the wing's chord in such a manner that the airflow at the boundary doesn't separate so quickly.
nice postDoesn't matter if it is a spelling bee site. Sometimes my typing isn't all it should be, either.
It matters if you communicate what you intend.
If you're trying to get technical, be as correct as possible since that minimizes misunderstanding.
The critical Mach number has not too much to be with overall drag; it defines critical Mach: the speed at which a supersonic shock wave begins to form on the wing and/or fuselage. Overall, the P-51 is MUCH less "draggy" than the Spitfire. The main drags were profile drag of the lifting surface, profile drag of the fuselage, cooling drag, and friction drag.
The P-51D has the best fuselage drag of any WWII piston combat aircraft. Period.
The P-51D has very low drag near its top speed, compared with other aircraft of the time.
The cooling drag is close to zero due to the Meridith effect.
Friction drag is quite low compared with most other fighters.
The combined effects of these account for the P-51 being so fast on such ordinary power. Definitely faster than most Spitfires, despite being a ton or more heavier. Late Spitfires were faster than earlier ones, but that came with considerably more power. By the time the P-51H showed up, it had more power, too, and showed all Spitfires a clean pair of heels easily.
But, by that time, it didn't much matter because everyone was interested in jets anyway. The Hunter, F-86, and Gnat were all pretty decently close to one another in performance. The Gant just couldn't perform well for very long on only internal fuel. The EE Lightning, despite being a Mach 2 airplane, was similarly range-limited. I once had a former Lightning pilot tell me he COULD get to Mach 2, but only if he was headed "toward the fuel." He said, tongue in cheek, that if he ever got going Mach 2 headed away from the fuel, he'd never get back to the fuel.
The P-51 wing IS a laminar flow wing back about as far along the chord as any laminar wing in WWII was. Later, we got even better laminar flow wings, but not during WWII on a piston combat aircraft. For all it's supposed mastery, the Ta 152 wasn't faster than P-51H and not much faster than a Tempest/Fury/Sea Fury (close to the same family). Most the late-war super-pistons were quite good and quite comparable, regardless of country of origin. Everyone learned a lot during wartime development. Everyone had decent engines, at least when manufactured with care, decent fuel, and decent airframes.
The British were flying 4 and 5-blade props while the Germans were using very wide-chord 3-blade props all with similar power. The difference in top speed wasn't much.
Cheers.
uummm i said you can look at the profile of the P51 wing and compare it to a profile of a laminar flow wing and see the difference.If you can deduce drag and laminar flow just by looking at a wing why did or do thy need wind tunnels? F1 cars dont look fast, only the fact that they are makes them seem so and they all look equally fast or slow while in practice there are huge differences. Nobody at NAA claimed the P-51 Mustang I had a laminar or lamellar flow wing, it had a high speed low drag wing and being "fat" is a distinct advantage, giving more room for fuel, munitions wheels and any other stuff. With the same engine the P-51B /D was faster and more economic than the Spitfire at all speeds up to the transonic range but at those speeds you are in danger of structural damage and props falling off. The lower drag of the P-51 was only partly due to its wing, the cooling set up was better and the overall design and build of the fuselage was better. A layman's logic dictates that fat = draggy but research by NACA showed that putting the thickest part of the chord further back delayed the onset of turbulence giving less drag in the speed ranges that prop aircraft use.
Edit, I studied metallurgy the words laminar and lamellar were used as synonyms, I have also seen the same in aerodynamics, is there actually any difference?
this is the onset of compressibility, not drag.putting the thickest part of the chord further back delayed the onset of turbulence
the spitfire wing? which one?None of this adds ups. One, the Spitfire's wing could house 1 .50 Browning and 1 20mm Hispano cannon, or 2 20mm Hispano cannons in each wing.
And two, the P-51 overall is significantly less draggy than the Spitfire. On the same power, the P-51B/D was 35-40 mph faster at least than the Spitfire IX. That speaks to better aero alone.
I'm far from knowledgeable on the detailed intracices of aircraft, but even I understand this.
Qute correct, add to that the dragging of ammo boxes over the wing, denting the shit out of themFrom what I've been able to understand the Laminar flow wing wasn't as good as it is made out to be, the reason being that manufacturing imperfections, damage, general wear and tear and even dirt and debris caused the laminar effect to be decreased so that's why I question it's overall effect, the real world is very different to a nice clean lab. Much is written about the 30mph advantage the P51 had over the Spit but how much of that is caused by the wing?, I feel it's the less glamorous drag caused by cannon barrels, blisters, stubs, tail wheel, exhaust and windscreen angle that has more of an effect on speed and drag between the two than the difference in the wings, as for maneuverability you only have to look at the Spiteful, the first one was a MkXIV with laminar flow wings, the overall consensus was it had worse handling than a standard MkXIV, particularly at lower speeds.
first to shock, the first part of the airframe to accelerate the airspeed into compressibility, not a low speed issue but a high speed problem.I have read on here that the windscreen on the Spitfire is the first to "shock", I have no idea whether that means it causes high drag at lower speeds, as compared to the buckets they call radiator scoops on the Mk XIV Spitfire, for example.
One bucket was just as draggy as I expected because the MkI and Mk V only had one, the Mk XIV I specifically mentioned had two.first to shock, the first part of the airframe to accelerate the airspeed into compressibility, not a low speed issue but a high speed problem.
the bucketts were in the boundary layer. so were taking up air that had already been slowed down. so you could call then 1/2 bucketts
they were not as draggy and you would first expect. but nowhere as good as the P51 Tunnel ram.
Since no profile of any WW2 aircraft actually was laminar flow we can all look at as many profiles as we think fit, what do they look like? How/ why was the Spitfire more economic on cruise settings, that isnt what I have read at all.uummm i said you can look at the profile of the P51 wing and compare it to a profile of a laminar flow wing and see the difference.
i didn't say NAA claimed the P51 had a laminar flow wing. but i have observe may posts claiming that. and it these posts i am addressing.
the P51 was not more efficient at all speeds. the spitfire was more economic at cruse for example, and had a much higher Mach number as examples.
correct the cooling set up was a real advantage
you wrote
this is the onset of compressibility, not drag.
ummm no, the HS.404 aircraft cannon variant, was 38kg amd the U.S. AN/M2 was 28kg, which is a considerable difference.the .50 browning is about the same size and weight as a 20mm cannon
compare British ww2 models as used.ummm no, the HS.404 aircraft cannon variant, was 38kg amd the U.S. AN/M2 was 28kg, which is a considerable difference.
The AN/M2 was also much shorter in length overall, too.
B24, was a true laminar flow wing.Since no profile of any WW2 aircraft actually was laminar flow we can all look at as many profiles as we think fit, what do they look like? How/ why was the Spitfire more economic on cruise settings, that isnt what I have read at all.
nice post
The cooling drag is close to zero due to the Meredith effect.. misleading. all fighter aircraft uses meredith effect to some existent. the P51 did this well.
But the original north american XP51 plans had a chin mounted radiator. this was changed due to British air ministry influence. firstly thinking the P51 as a P40 replacement. so the british North africa exspericans came into play.
the Hurricanes had less radiator damage than the P40. north americans purchase of curtis P46?? and the gaining of the internal flow Tech. but this was just the start point.
the real advantage was the scoop itself.
the bleeding edge scoop, so you are 100% correct when you wrote the P51 fuselage was quite slippery and not wrong when you wrote about the meredith effect but the meredith effect is a smaller part of the story than it really is. so its not so much that the meredith effect was increased to a point where it zeroed out drag. is more that the drag was decreased to match the meredith effect.
you compared to a spitfire. i have never found the numbers to do a good direct comparison. that's even after converting from Rabble gallons to real gallons. and its even just not what spitfire Mk but what wings it had, what blower etc. this gets really messy on the spitfire side really quickly.
so i would be interested in what anyone else has used?
but is we just look at 3 numbers, altitude, cruise speed in conjunction with fuel consumption. the spitfire could cover more distance, thus it is more slippery at cruse speeds of about 260Knts
But i would expect and the number seem to confirm, that at higher speeds. the spitfires more conventional wing, the drag would increases more than that of the P51 wing, and with speed the p51 wing would lose " angle of attack" and the conventional profile of the spitfire wing would keep on producing life, or excessive lift requiring a negative angle of attack.
That spec is for the RAF's HS.404...compare British ww2 models as used.
B24, was a true laminar flow wing.
laminar flow as designated by the aviation industry.
correctThe cooling drag of the P-51 was near net zero, no matter how it was achieved. No other airplane in WWII achieved zero cooling drag ... only the P-51.
A P-51 variant with a chin radiator was never built.
A Spitfire never flew that could match a P-51 for range.
A P-51D at 300 mph TAS burned about 55 - 60 U.S. gallons per hour at typical cruise altitudes in the ETO. 1 U.S. gallon is 1.2 Imperial gallons.
For cruising, the Spitfire IX recommended speed was 170 - 200 mph. There is no chart for power, speed, and fuel burn all at the same time that I can find in the pilot's manual. Go figure. For a Spitfire Mk XVI or a Mk IX, about +4 psi boost, 2650 rpm and will burn 71 Imperial gallons per hour, which is 60 US GPH. So, at 60 gph, the Mustang was cruising about 300 mph and the Spitfire speed is basically unknown. But we KNOW the Merlin Spitfires were slower than the Merlin Mustang at maximum power, so we can assume they were slower at cruise, too, without much chance of an error. Likely they were a bit slower, but not that much ... but we can't prove that with the standard pilot's manual. I could ask tomorrow at the Planes of Fame, assuming Steve Hinton is there. Maybe. We'll see.
But the Merlin Spitfire didn't generally out-speed or out-range the Mustang, ever. It DID climb better and was a better maneuvering turner. I'd prefer the Spitfire's cannons to the P-51's MG, too. But a Spitfire was never very good at stretching range or going especially fast ... except in a dive. It WAS the best diving piston fighter of the war, as far as I know. That has much more to do with gravity and a slightly better critical Mach number than any drag number at cruise speed though.
that he did.View attachment 736167
"Laminar Flow" wrt aerofoils is always good for an argument. I subscribe to Eastman Jacob's definition, as he was the man who joined the dots with the research results and first coined the term.