P-51D maneuvrability - what it was in reality ...

[GrauGeist]

The other thing I find interesting, is the allegation that NAA "stole" Curtiss' ventral radiator design.

Yes, the early iterations of the XP-40 had it and the later XP-46, but so did the Italian's Macchi MC.202 and Caproni F.6 as well as designa by Fairey, Hawker Boulton-Paul, Heinkel and a host of other manufacturers.

Even Supermarine toyed with the idea for the Spitfire.

 

[pbehn]

@Clean32 you said:
"posting the other trash artist concepts to finish the story of the previously posted artists trash concepts.
being that all these trash concepts were presented to the British air ministry."

Drgndog posted the P-509 conceptual drawing, which eventually became the NA-73X.

You posted the P-500 concept drawing, which was a proposal for a lightweight fighter concept powered by a Ranger engine with the hopes of selling it overseas. It was designated NA-53 and predated the BPC's request to NAA, therefore moot to this discussion.

I think a major problem for the RAF, the BPC and the US military along with every other military is that everyman and his dog, plus the dogs fleas had design concepts and "projects". Figuring out what was realistic and could actually work and be put into production by the people making the proposal must have been a nightmare. In 1940 many things were still being learned about high speed flight, airflow, resonance etc and also what was actually needed for a fighter.

 

[GrauGeist]

Very true and even the airwar itself was entirely different in 1945, than it was in 1940.

 

[drgondog]

Nice
if you dig really deep, the Naca coding of the P 51 wing came post wing development. as i understand it both the spitfire and P51 did not use Naca developed airfoils.

Spitfire NACA 2213 root, NACA 2209.4 tip. For NA73X through P-51M NAA/NACA 45-100, for the XP-51F/G/J, P-51H and P-82 NACA 66-(1.8) 15.5

" wing thickness" yes it was a thick wing, had a lot to stuff in there, add to that the British air ministry's experiences with the P40 wing skins wrinkling in North africa, this information being passed on. so we could say the best thick wing around.

RAE/RAF had zero input to the development of the NAA/NACA 45-100 airfoil. No input regarding 'wrinkled skins' of P-40 wing. The Brits 'bought' NA-73 based on a.) their impressions of the high quality of the BT-9 and AT-6, b.) Commitment to adhere to the British Specification F.18/39 Operational Requirement O.R.73, and c.) because they were impressed enough with the Cooling system scheme of the P-509 to believe that it would actually work.

As to 'thick', yes relative to Spit, but 'thin' relatively speaking when compared to F4U (NACA 23018 root), Typhoon (NACA 2219), F8F (NACA 23018) - about the same P-38 (NACA 23016), FW 190 (NACA 23015.5), F6F (NACA 23015), P-39 (NACA 0015), P-40 (NACA 2215). To the P-40, same family as Spit but 2% thicker at Max T/C.

economical, MPG. the spit Mk IX was slower in transport, but that was when the aerofoils lift equaled the weight with no angle of attack as at the same speed the P51 had a heap of angle of attack, thus drag. the P51 needed another 30-40 mph to eliminate the angle of attack but still had a thick wing to push though. P51D

The first target for flight test for both range and endurance (slightly different locations on CD vs V plot), is where Induced Drag CDi = Parasite Drag Cdp. The best cruise range requires more power and speed than best endurance.

To your statement - Yes for given flight speed and altitude the Spitfire CL will be lower than Mustang because of greater wingspan and lower GW. Because that is true, it follows that at that speed and CL it will have lower Induced Drag CDi than the Mustang. What you miss here is that the Parasite drag of the Spitfire is quite higher than the Mustang. So, present sources please?

i didn't read back on what i wrote for the P51, and yes it didn't have a pich down as comparability formed at equal distance on both upper and lowered sides of the wing. every thing else is bang on.

?????? Mostly incoherent, but please elaborate>

BUT. the P51 had 3 profiles. Inner, mid section and tip. the tip had a bit more of a concave under skin to try and fix low speed handling, the inner section was quite sweeped back. the big advantages of this are not often talked about. i have read that this had a small part to play in the Valiants crescent wing design,

The root chord was 16.5% at C/L, straight taper to 9%. The tip airfoil was different. No concave 'under the skin'. The 'strake or crank' was not 'quite swept back' although the D was more pronounced angle to accomodate new wheel well door. Coversely the P-51H was straight LE. The 'big advantage' was to locate the main gear forward of the front spar.

Sweep? No. The spar was perpendicular to the C/L of airframe. The leading edge and trailing edge were straight taper to the Tip.

i have never found any information of transonic flight of the P51H or why this was illuminated in the H? although i would sagest its advantages were just not known at that time.

????? Essentially the same as D but shock wave becan slightly further aft of D wing section location

 

[Peter Gunn]

Nice
if you dig really deep, the Naca coding of the P 51 wing came post wing development. as i understand it both the spitfire and P51 did not use Naca developed airfoils.

" wing thickness" yes it was a thick wing, had a lot to stuff in there, add to that the British air ministry's experiences with the P40 wing skins wrinkling in North africa, this information being passed on. so we could say the best thick wing around.
economical, MPG. the spit Mk IX was slower in transport, but that was when the aerofoils lift equaled the weight with no angle of attack as at the same speed the P51 had a heap of angle of attack, thus drag. the P51 needed another 30-40 mph to eliminate the angle of attack but still had a thick wing to push though. P51D

i didn't read back on what i wrote for the P51, and yes it didn't have a pich down as comparability formed at equal distance on both upper and lowered sides of the wing. every thing else is bang on.

BUT. the P51 had 3 profiles. Inner, mid section and tip. the tip had a bit more of a concave under skin to try and fix low speed handling, the inner section was quite sweeped back. the big advantages of this are not often talked about. i have read that this had a small part to play in the Valiants crescent wing design,
i have never found any information of transonic flight of the P51H or why this was illuminated in the H? although i would sagest its advantages were just not known at that time.

Hey partner, just a small piece of advice, here's who you're arguing with:

Amazon.com

 

[Geoffrey Sinclair]

Nice
if you dig really deep, the Naca coding of the P 51 wing came post wing development. as i understand it both the spitfire and P51 did not use Naca developed airfoils. " wing thickness" yes it was a thick wing, had a lot to stuff in there,

My information is both the Spitfire and Mustang used NACA airfoils, the Mustang's had more internal room.

add to that the British air ministry's experiences with the P40 wing skins wrinkling in North africa, this information being passed on. so we could say the best thick wing around.

26 October 1940, NA-73X first flight
February 1941, 100 Tomahawks arrive at Takoradi, West Africa
April 1941, 250 RAF squadron issued with Tomahawk in Egypt.
May 1941, 3 RAAF squadron issued with Tomahawk.
June 1941, 2 SAAF and 112 RAF squadron issued with Tomahawk.
7 June 1941, invasion of Syria, 3 RAAF flying in support from 8 June.
11 June 1941, 250 squadron moved into the Western Desert.
6 July 1941, 2 SAAF squadron moved into the Western Desert.
August 1941, first NA-73 acceptances.

So how and when did reports of Tomahawk wing skin problems make it back to North American in time to change wing thickness? Thicker wing skin?

economical, MPG. the spit Mk IX was slower in transport, but that was when the aerofoils lift equaled the weight with no angle of attack as at the same speed the P51 had a heap of angle of attack, thus drag. the P51 needed another 30-40 mph to eliminate the angle of attack but still had a thick wing to push though. P51D

The Spitfire VIII/IX had a fuel consumption of around 5.75 miles per imperial gallon at economic cruise, 170 to 200 mph, dropping to 4.85 mpg at 320 mph at 20,000 feet. What fuel consumption figures are being used for the P-51?

 

[Admiral Beez]

The Spitfire VIII/IX had a fuel consumption of around 5.75 miles per imperial gallon at economic cruise, 170 to 200 mph, dropping to 4.85 mpg at 320 mph at 20,000 feet. What fuel consumption figures are being used for the P-51?

Is that Imperial or US gallon? Your post reminded me of a anecdote from decades ago.

Here in Canada we had resistance to 1980's metrication in car reviews, with Canadian readers more accustomed to US car magazines demanding mpg be shown in addition to or instead of litres per 100 km. I remember the local Canadian newspaper replying to complaints that they'd include mpg, but Imperial not US gallons, reminding its readers that Canada has never used US gallons for cars. I believe it's the same for aircraft for that matter.

 

[Shortround6]

So how and when did reports of Tomahawk wing skin problems make it back to North American in time to change wing thickness? Thicker wing skin?

The P-36/Mohawks did have wing skin problems.
Mohawks-Tomahawks? What's few letters between friends
And over a year?

I have no idea what they changed or the wing skin thickness but the long nose P-40s (Tomahawks) gained over 100lbs weight in the wings over the P-36/Hawk 75. The P-40D/E gained over another 100lbs in the wings from the Long noses. But they were designing the P-40D/E before the Tomahawks even got to England let alone NA. In fact to borrow Mr Sinclairs work.

April 4th 1940, first flight of a production P-40
June 6th 1940, first flight of a French contract Hawk 81-A.
Sept, 1940, P-40D order is placed
Sept, 1940 First Tomahawks reach England.
Oct 16th 1940, delivery of the 200th P-40. Ex French machines (now British were sandwiched in) raising the total production.
26 October 1940, NA-73X first flight
February 1941, 100 Tomahawks arrive at Takoradi, West Africa
April 25th 1941, First flight of Mustang I, AG345.
May, 1941 First production P-40D Delivered.


The P-40/Hawk 81-A had a normal gross weight of 6,807lb and a max gross weight of 7,173 lbs.
The P-40C/Hawk 81 A-3 had a normal gross weight of 7505lb and a max gross weight of 8,013lb lbs.

Unless somebody has copy of communications or memo's this does not look good.

 

[Writer]

Has anyone here read the book "Wing Leader" by Johnny Johnson, the RAF pilot who flew Spitfires during the war and claimed 38 victories? He recounts that during the Dieppe operation in July/August 1942, he was flying a Spitfire Mk V and was out-turned by an FW 190. He only escaped being shot down by diving away over a British destroyer, whose anti-aircraft guns deterred the German pilot from following. This is the only account that I can find of such a happening, as the Spitfire was rated as able to turn inside a BF 109 or FW 190 but apparently not so in this case. It would be interesting to know who was flying the 190. Almost certainly a pilot from JG2 or JG26, both of which were renowned for having many aces and experienced pilots in their ranks.

 

[GrauGeist]

Altitude played a key factor with an Fw190's performance.

At lower altitudes, a turning fight with a 190, especially if flown by an experienced pilot, would not end well for an adversary.

 

[Peter Gunn]

Is that Imperial or US gallon? *SNIP*

African or European swallow?

...

Someone had to say it...

...

I'll get my coat.

 

[Clayton Magnet]

I believe it's the same for aircraft for that matter.

Aviation in Canada is a mess of different units. For example, fueling a jet in Canada involves the fuel being dispensed in Litres, but calculated onboard the aircraft in Pounds, while the aircrafts internal fuel capacity will be listed in US gallons.

 

[Admiral Beez]

Aviation in Canada is a mess of different units. For example, fueling a jet in Canada involves the fuel being dispensed in Litres, but calculated onboard the aircraft in Pounds, while the aircrafts internal fuel capacity will be listed in US gallons.

Ah yes, the Gimli Glider.

Gimli Glider - Wikipedia

en.wikipedia.org

Poor fuel management, but superb soaring/slipping skills.


View: https://www.youtube.com/watch?v=3ffryZAd4Nw

 

[Norman]

Don't forget, early 51s without ventral filet would lose the tail completely in a hard diving turn to the right.

 

[pbehn]

Don't forget, early 51s without ventral filet would lose the tail completely in a hard diving turn to the right.

Every time?

 

[GrauGeist]

Would be interesting to read a source for that...

 

[GregP]

Early P-51s and even late P-51s had trouble with a snap roll and a slow roll.

The culprit was the CG moved aft with radios and weight gain. Instead of a stick force of 6 lbs per g, it was more like 1 1/2 lbs per g, making it very easy to over-stress the airframe. The stick force reversed at about 4-g. No aerobatics if 40-gal or more in aft fuselage tank.\\So, it was much more of a stick-force issue than a real weakness. If you were a good pilot, you could fly most maneuvers without overstressing the airframe. If you were ham-handed, maybe not.

 

[drgondog]

Don't forget, early 51s without ventral filet would lose the tail completely in a hard diving turn to the right.

True that dorsal fin improved flow over the empennage, but reverse rudder boost tab was installed to 'reduce' hard rudder input. Also true that left rudder input was required in a dive for yaw control as TAS exceeded ~400mph.

In any case ALL US fighters that designed to AAC Materiel Command Aircraft Structural Design Standards (incl Mustang) were found to be deficient in empennage ultimate load design for the fin/rudder.

The Mustang was perhaps moreso because of pronounced yaw response to power changes, requiring trim adjustment. A dynamic high g manuever such as a high speed slow roll or diving turn created asymmetric forces on the empennage which in some cases did cause structural failure.

 

[SaparotRob]

Out of curiosity, are there references to the CW-21 in official documents about structural dificiencies, empennage wise? It's a beautiful plane but I can't see how that tail stayed attached.

 

[drgondog]

I do not know of any such docs.