# P-51B dorsal fin



## fastmongrel (Dec 4, 2011)

I had always thought the dorsal fin mod to the the P-51 only came in with the P-51D but I have just come across a photo on google of a flight of RAF Mustang IIIs







Had a look for some more info on this but no luck. Were they changeover aircraft built using a mix of parts or was this a service modification. Any info would be great as I am thinking of building a Malcolm canopy Mustang III and might consider modding the kit.


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## FLYBOYJ (Dec 4, 2011)

I believe the dorsal fin was retrofitted to P-51Bs, Cs and Ds in the field and incorporated in production batches. Check out the photo and this link...

http://www.swissmustangs.ch/20214/20295.html


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## Airframes (Dec 4, 2011)

Yep. When the 'D' was introduced, the cut-down rear fuselage caused some lateral stability, so the dorsal fillet was added. It was found that this also improved handling on the 'B' and 'C', and some airframes were modified, initially I believe at BAD1 Burtonwood, UK, for the USAAF.
No doubt Bill might be able to provide more detailed information regarding USAAF aircraft. As far as I have seen, RAF Mustang IIIs were mainly as standard 'B' and 'C', with some later airframes being received with the dorsal fillet. Note that the pic posted is post January 1945, judging by the upper wing roundels. Checking my listings of airframes issued to the RAF, there is no distinction which had the fillet, but if this can be narrowed down to a NA production batch, I have the US Bu Numbers which cross-reference with the RAF serial numbers, which should provide relevant info.


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## fastmongrel (Dec 4, 2011)

FLYBOYJ said:


> I believe the dorsal fin was retrofitted to P-51Bs, Cs and Ds in the field and incorporated in production batches. Check out the photo and this link...
> 
> Swiss Mustangs



Thanks for that link, nice site added it to my favourites.


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## fastmongrel (Dec 4, 2011)

I am doing some research on the Mustang III because I have a plan to build a model of every aircraft my late father worked on during his time as an RAF instrument fitter. I am not looking for particular aircraft because I dont (apart from a couple of cases where there are aircraft as a backdrop in photos) have airframe numbers to work from. 

I will start the project with the Mustang because it was the first fighter a/c Dad worked on. I havent done any aircraft modelling for nearly 40 years so I thought it best to start with something relativley simple (I might have just shot myself in the foot there) rather than jump straight into a Short Sunderland or Avro Lancaster for example.

Its quite a list of aircraft to keep me happy for a good few years Dad started working on Percival Proctors and ended up working on Vickers Valiant Nuclear bombers 20 years later.


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## GregP (Dec 4, 2011)

The dorsal fin was never developed as a result of stability lost when the bubble conopy was fitted, as popularly believed.

In reality, whenever power is increased without any redesign, stability is lost. The switch from the Allison V-1710 to the Merlin V-1650 increased the power due to the Merlin's superior supercharger design (thanks Dr. Stanley Hooker), and stabiility was lost from the P-51B model forward. When they fitted the bubble canopy from the Hawker Typhoon to the Mustang, the aircraft STILL had the stability issue the P-51B had. The dorsal fin extension was developed to counter this because it did not interfere with production and could be retrofitted. Yers, they COULD have enlarged the vertical fin ... but that would entail a production stoppage that was not considered worth the delay.

Many dorsal fin extensions were retrofitted, but an entire shipoad of dorsal fin extensions were lost to a U-boat sinking and the dorsal fins were fitted much more slowly than anticipated. Some were siply fabricated locally from Aluminum.

You can see the British answer to fitting more power to the Spitfire as the aircraft was developed. Check out the fin on any Griffon-powered Spitfire compared with, say, a Mk V. You will note the fin area was greatly increased. It was the same problem as the Mustang dorsal fin extension.


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## Airframes (Dec 4, 2011)

Canopy from a Typhoon? Don't think so.


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## FLYBOYJ (Dec 4, 2011)

Info...

P-51 Malcolm Hood


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## FLYBOYJ (Dec 4, 2011)

Here ya go guys, from another site. This mod was also structural.

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## GregP (Dec 4, 2011)

Airframes. You might not think so, but North American did.

The canopy was diveloped by the British for the late-model Typhoons and Spitfires. The concept was copied by North American. In fact, the first Mustangs with the bubble camopies use Typhoon canopies that North American had modified as far as the canopy frame and mounting go, but were otherwise stock late-model Typhoon canopies.

Since I live in Southern California, we get a LOT of former North American Aviation employees (as well as other aviation manufacturers, including Northrop, Douglas, etc.) at the museum. Many worked on Mustangs. We even get visitors who helped design the various aircraft. Pete Law of the Lockheed Skunk Works is a frequent visitor. Anyway, more than 20 visitors who used to work at North American confirmed this fact and I, for one, believe them, especially when they show up with original documentation in tow.

Obviously the P-51H and TF-51 have canopies that are different, but the "D" model canopy was pure Hawker Typhoon late-model.

View attachment 185303


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## GrauGeist (Dec 4, 2011)

The "Miles M.20" canopy design was indeed adapted to the Tempest Typhoon and adopted by North American (P-51) and Republic (P-47)


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## Readie (Dec 4, 2011)

GregP said:


> Airframes. You might not think so, but North American did.
> 
> The canopy was diveloped by the British for the late-model Typhoons and Spitfires. The concept was copied by North American. In fact, the first Mustangs with the bubble camopies use Typhoon canopies that North American had modified as far as the canopy frame and mounting go, but were otherwise stock late-model Typhoon canopies.
> 
> ...



Great pic Greg. Thanks for posting it. The Typhoon was a bruiser of a plane
John


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## fastmongrel (Dec 4, 2011)

The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane. 

Got my tin hat on and waiting for the incoming


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## Readie (Dec 4, 2011)

fastmongrel said:


> The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane.
> 
> Got my tin hat on and waiting for the incoming




Hahaha...time to pull up the drawbridge 

John


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## FLYBOYJ (Dec 4, 2011)

fastmongrel said:


> The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane.
> 
> Got my tin hat on and waiting for the incoming



Well maybe if we designed the MG........


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## Readie (Dec 4, 2011)

FLYBOYJ said:


> Well maybe if we designed the MG........



A great example of an Anglo- American sports car would be the AC Cobra. British brains and American V8 brawn.
What a car !
Worth a fortune today
John


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## Wurger (Dec 4, 2011)

fastmongrel said:


> The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane.



You have forgotten about mentioning the Polish idea of long range flights and the first reconnaissance flight by Lt. Janusz Lewkowicz, on 27th September 1942 from England to Stavanger , Norway and back flying Mustang Mk I.


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## Airframes (Dec 4, 2011)

Whilst I agree that the design concept of the P51 'bubble' canopy is similar to that of the Typhoon, the shape and size are different, as was that of the MkXVI 'low-back' Spitfire (and other late Marks) compared to the Typhoon.
I don't dispute that the P51D canopy is 'Typhoon type', but it's not a true Typhoon canopy.

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## GregP (Dec 4, 2011)

The shape and size are the same, at least on the early examples. Maybe different later, but I don't think so. The lines are exactly the same on our two P-51D's and they are both late models.


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## davparlr (Dec 4, 2011)

fastmongrel said:


> The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane.
> 
> Got my tin hat on and waiting for the incoming



Okay, I'll bite for fun.
a. British idea. I believe the Brits just wanted P-40s. It was NA engineers that said they could provide a better plane. The Brits only said okay.
b. British money, British engine, British canopy and British drop tanks. It not the ingredients that make the cake good, it the mixing. The Brits had the money, the engine, the canopy and the drop tanks, but, they could make no Mustang!


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## Readie (Dec 5, 2011)

davparlr said:


> Okay, I'll bite for fun.
> a. British idea. I believe the Brits just wanted P-40s. It was NA engineers that said they could provide a better plane. The Brits only said okay.
> b. British money, British engine, British canopy and British drop tanks. It not the ingredients that make the cake good, it the mixing. The Brits had the money, the engine, the canopy and the drop tanks, but, they could make no Mustang!




Me too...just for fun.

'The Brits had the money, the engine but, they could make no Mustang'

We didn't need too...we had our wonderful Spitfire.
The PR version could fly to Berlin and back.

John


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## Milosh (Dec 5, 2011)

Readie said:


> Me too...just for fun.
> 
> 'The Brits had the money, the engine but, they could make no Mustang'
> 
> ...



Ah, was that to take photos of German fighters shooting down American bombers?


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## Arossihman (Dec 5, 2011)

fastmongrel said:


> The P-51 British idea, British money, British engine, British canopy and British drop tanks what a great American plane.
> 
> Got my tin hat on and waiting for the incoming



Great how we play so well together is'nt it!


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## Readie (Dec 5, 2011)

Milosh said:


> Ah, was that to take photos of German fighters shooting down American bombers?



We had flash PR to show the LW shooting down British bombers too...

John


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## Airframes (Dec 5, 2011)

Sorry to continue digressing from the original topic of this thread, but Greg, I have to continue to disagree re the Typhoon canopy.
It is a common misnomer that the Typhoon canopy was used on the P51D/K and the P47, an error which has probably grown up from statements such as "We liked the idea of the all round vision canopy, so used the Typhoon canopy on the... " for example. 
What in fact is meant here is that, the _concept_ was used, and a _similar style_ of canopy designed and fitted to both the above aircraft.
The glazed section on the standard 'bubble' canopy fitted to the Typhoon, Tempest and Sea Fury is approximately 48 inches in length, not including the lower frame and, overall, it is a relatively small, low-profile canopy.
The glazed section on the Inglewood - built P51D canopy is approximately 72 inches long, with the profile, although very similar, being different, higher and elongated, and the cross section a different, more compound - curved shape at the forward frame. The Dallas - built P51D and K differed again, with a different, more pronounced, rear profile, whilst the TF-51D, and some other twin-seat P51s, had an even longer, higher canopy.
(Some confusion may arise with the Sea Fury, as there are at least two currently airworthy examples displaying a longer, non-standard canopy, normally associated with a two-seat conversion.)
The attached scale drawings should clarify things, albeit they are rather feint. Typhoon top, Inglewood-built canopy centre, Dallas bottom.

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## Wurger (Dec 5, 2011)

I agree with Terry.The difference is noticed very clearly. Of course the conception of the drop-shaped conopy might have been picked up and adjusted by the US designers. But it is still the English idea. Am I right?


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## Readie (Dec 5, 2011)

Martin Baker - Martin-Baker MB5

http://www.martin-baker.com/Sub-Navigation/History/Martin-Baker-MB2.aspx

The MB2 was a pioneering design of pilot visibility.
The MB5 is a beauty.

John


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## Airframes (Dec 5, 2011)

Yes my friend. However, there is a possibility that an original Typhoon canopy _glazing_ was fitted to a custom - made frame, and fitted to a cut-down P47 at Burtonwood, UK, as an experiment.
I would have to find the info to confirm, but whatever, the production P47 'bubble' canopy was different again compared to the Mustang and Typhoon.

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## GregP (Dec 6, 2011)

Airframes, you can believe what you want in good health and with good wishes. I did not claim the entire P-51D / K line used Typhoon canopies. What I said was the first two (or several) bubble canopy versions of the P-51D were built with Typhoon canopies. I have seen the documentation of same, and I believe it. If you don't, so be it.

What came later was probably North American's idea of how to proceed. The fact is they did use Typhoon canopies to study the concept. Whatever cvame later was what was required to meet the Mustang front canopy line with a blown canopy instead of using alimunin to make the Typhoon canopy strealimed enough when it was used a a "test vehicle."


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## Siegfried (Dec 6, 2011)

The introduction of the tail fin fillets is also associated with the introduction of the tail 66 gallon tail tank, which made the P-51 very difficult to fly and eventually
forced missions starting with partially filled tail tanks; the fillet helped stabillity. 

The P-51 had some minor stabillity issues: it could under no circumstances be snap rolled; some aircraft were lost in attempting this manouver. These handling issues were resolved in the P-51H which among other modifications incorporated a longer tail to increase the tail momment arm. These improved the handling so much the aircraft was now considered to have good enough handling for carrier use however the war ended before any serious full scale carrier builds could be made.

The Merlin would have been unneccesary for the P-51B The two stage Allison V-1710-121 was available at this time and could have provided equal performance; it may even have been easier to produce as the two stage V-1710-121 did not use bulky intercoolers (used water injection when needed) and could have been introduced with less airframe mods.

The idea for the bubble canopy seems to have been around for a long time think of the japanese fighters and P-39, also note that had the Luftwaffe chosen the He 112 over the Me 109 a bubble canopy would have been standard on the Luftwaffe's principal fighter: the FW 190A being likely the earliest mass implementation of blown canopy as opposed to a glass house type: it certainly inspired the allies to get their own skates on in this area.

Some pilots reported slighty rougher handling at mach limit due to the bubble canopy and they occaisionally lost diving competitions with late model Me 109 which by then had the new tall tail rudder with the horn balance replaced (which caused high speed dive problems). There would only be a fraction of a tenth of a mach in this.


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## GregP (Dec 6, 2011)

Though I believe the 2-stage Allison would not have been a bad choice (a bit prejudiced there perhaps), the Merlin wasn't a bad choice. As it turned out, the Merlin-powered Mustang was a great plane indeed, worthy of mass-production if ever a plane was.

The bubble canoopy never was a lower-drag installation, but it DID give a lot better visibility. In a diving attack, I doubt if the difference between a bubble canopy and the turtledeck type was a big enough difference to change the outcome of the fight. But I could be wrong if the apparent loser started his dive high enough ... maybe he COULD escape. I suppose we'd have to ask a combat veteran who had flown both types of canopy enough to know. I'll try that next ime we get some veterans at the museum. It doesn't mean the veterans who show up would know, of course, but I can ask.


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## drgondog (Dec 6, 2011)

Greg - Lednicer did a nice paper on studying the P-51B/D, Spit 9 and Fw 190D to examine the pressure distributions. While the design may or may not have considered the aerodynamics of the windscreen canopy, the D was designed with a lower angle than the B.

The P-51D canopy was superior aerodynamically to the P-51B (marginally), about the same as the Fw 190D and much better than the Spit 9.

The key distinction was a stagnation pressure build up at the base of the P-51B and Spit 9 windscreen. Apparently when the angle on the windscreen on the D canopy was reduced by 5 (? have to check and I'm consumed by indifference at the moment) degrees, it was enough to eliminate the problem.


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## drgondog (Dec 6, 2011)

GregP said:


> Airframes, you can believe what you want in good health and with good wishes. I did not claim the entire P-51D / K line used Typhoon canopies. What I said was the first two (or several) bubble canopy versions of the P-51D were built with Typhoon canopies. I have seen the documentation of same, and I believe it. If you don't, so be it.
> 
> *Greg - what documentation? Gruenhagen doesn't mention it nor does Wagner, Jackson. Looking at the pictures of Chilton flying the prototype (modified P-51B-1) makes it pretty clear that the canopy on the first prototype pictured in flight is not a Typhoon canopy. If a Typhoon canopy was installed at one time there certainly aren't any readily available photos showing it? The next two were modified P-51B-10's - with same canopy as the prototype and succeeding P-51D-5's *
> 
> What came later was probably North American's idea of how to proceed. The fact is they did use Typhoon canopies to study the concept. Whatever cvame later was what was required to meet the Mustang front canopy line with a blown canopy instead of using alimunin to make the Typhoon canopy strealimed enough when it was used a a "test vehicle."



So back to the question. Why use a Typhoon canopy at all? Sitting in a Typhoon would give a designer and a pilot all the info they needed tod determine the value over a birdcage or even Malcolm Hood. The production versions had the same radio installation as the first prototype (43-12102), and that bird is the one most often shown flown by Chilton over the Santa Monica Mountains. 

I'm willing to be convinced otherwise - but it doesn't make a lot of sense to 'try' a configuration that required airframe mods once, then switch to a new design tailored for the airframe and re-modify the airframe to take the production version. The source for Typhoon canopies was in the UK. Tooling to build under license would take as much or more time than for a local US manufacturer. So, what documentation are you pointing to?

Regards,

Bill


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## Airframes (Dec 6, 2011)

Greg, apologies if you think I disbelieve you - I don't.
I was not aware that the first two P51D airframes had used an actual Typhoon canopy as a pattern/trials etc.
I have only seen one pic of the first prototype, converted from a 'C' model I believe, which appears to have a standard 'D' type bubble. 
It was/is only my intention to dispel the myth that Typhoon canopies were used in production.
Regards,
Terry.
EDIT: Sorry. Didn't see your post Bill. It's interesting that the only (almost) complete Typhoon in existence today, in the RAF Museum, Hendon, UK, only survived as it had been 'loaned' to the US for study and evaluation purposes. It was returned to the UK, in exchange for a Hurricane, in the late 1960s, with some parts missing.
It's possible that this was the airframe which influenced the P51D bubble canopy.


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## FLYBOYJ (Dec 6, 2011)

GregP said:


> Airframes, you can believe what you want in good health and with good wishes. I did not claim the entire P-51D / K line used Typhoon canopies. What I said was the first two (or several) bubble canopy versions of the P-51D were built with Typhoon canopies. I have seen the documentation of same, and I believe it. If you don't, so be it.



Could it have been possible that NA used ONLY the plexi glass portion of the canopy and modified it to fit the frame on these first aircraft?

I did work with a company called Cerrican (sp?) Aircraft transparencies located in Sylmar Ca. They made the first canopy for the F-22 and also made F-16 canopies there. If they had a scrap F-16 canopy they would sell the plexi glass bubble. I was told that homebuilders, Unlimited racers and even boat racers bought their scrap canopies and cut them down to fit a frame on their boat or aircraft.


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## Airframes (Dec 6, 2011)

That's the only possibility I can think of Joe. 
BUT - the Perspex part alone is 2 feet shorter than the P51D equivalent part, a lot narrower, and lower in side profile! This would mean a very odd-shaped frame, not to mention an awkward, if not impossible, joint/seal at the forward edge of the canopy to the windscreen.
Bearing in mind the fuel tank and radio equipment fit to the rear of the P51D cockpit, all covered by the canopy, and remembering what Bill stated about the prototype 'D' and its canopy, borne out by photos, I can't see that a Typhoon canopy, custom-framed or not, would even partly fit, let alone be safe, sealed and aerodynamically sound !


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## MikeGazdik (Dec 6, 2011)

Back to the dorsal fin. That would explain my confusion with this photo:



Most photos I have seen of this bird, she has no dorsal fin.


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## bobbysocks (Dec 6, 2011)

from P-51 Mustang Variants - P-51D - MustangsMustangs.com a pretty good site...

The signature change in the P-51D line was the new bubble canopy. The U.S. was behind the Brittish in canopy development. A Brittish company had designed and built the "Malcolm Hood" which improved visibility to the rear of the P-51B/C models. The U.S. was not unaware of the advantages of a bubble canopy design. NAA had built a wooden model of the P-51 with a bubble canopy for wind tunnel testing. The technology to build large curves of plexiglass "distortion free" at that time was being invented and developed. 

The Brittish had figured out how to make a bubble (also called "teardrop") canopy with unobstructed 360 degree view and they were beginning to use them on the latest model of Spitfires and Typhoons. The U.S. Army sent Col. Mark Bradley to England in January of 1943 to find out the workings of this new canopy and then find a way to get them on U.S. fighters. Bradley returned and began to pursue ways to incorporate the new style. The first U.S. fighter so tested was a Republic P-47.

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## bobbysocks (Dec 6, 2011)

Siegfried said:


> The introduction of the tail fin fillets is also associated with the introduction of the tail 66 gallon tail tank, which made the P-51 very difficult to fly and eventually
> forced missions starting with partially filled tail tanks; the fillet helped stabillity.
> 
> The P-51 had some minor stabillity issues: it could under no circumstances be snap rolled; some aircraft were lost in attempting this manouver.



the 85 gallon fuse tank was put in earlier versions and way before the fin mod. they took the off full but burned them down to 3o some gallons before switching to the drop tanks. with that tank full maneuvering was somewhat difficult. i believe it could be snap rolled. gregp and drgondog could say if they can or not since they have flown them.


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## GregP (Dec 6, 2011)

On the Typhoon canopy issue, we have had vets show up as well as people who built Northa American, Douglas, Northrop, Consolidated, and Vultee products. Not surprising since tey were all built around this area. At least two guys showed up with Noth American notebooks detailing installation of a Typhoon canopy on a modified B-model Mustang.

I had and have no reason to doubt them. They were just happy I could let them up into a Mustang cockpit again.

Again, you can believe it or not in peace. I do becasue I saw the notes and tech orders. If you don;t, that's OK, too ... I understand. In the end, it doesn't matter becasue they D's were built and made history anyway.


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## drgondog (Dec 7, 2011)

Mike - The dorsal fin was an add on - post July 1944. The dorsal fin was first believed to be a solution to stability issues that continued with the introduction of the P-51D-5 (no dorsal) along with the 85 gallon fuse tank in the P-51B/C/D.

When the P-51D-10 came out with production dorsal fin, NAA started sending field mod kits for all the Mustangs, including the B/C's. The primary field mods post July were dorsal fins for pre P-51D-10, and metal covered elevators for all P-51s to replace fabric covered.


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## MikeGazdik (Dec 7, 2011)

Roush must have added the fin to his Old Crow -B later. I used to have photos when it was first displayed, and I don't recall it being present. Neat info all!


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## drgondog (Apr 6, 2015)

I have failed for some reason to look at this thread for awhile.
Some points:
1. The shape and installation of the XP-51D (43-12102 was P-51B-1-NA number 10) canopy was NOT a Typhoon canopy. However the P-47 that had been fitted with the Typhoon canopy was brought by Bradley to NAA engineers to have a look. Bradley also responsible earlier for telling NAA to put a "100 Gallon" fuselage tank aft of seat - which resulted in the final 85 gallon design. As Terry has pointed out the obvious, the P51D and K and H canopies are all 2 feet or more longer.. with a distinctly elongated look when contrast to the Typhoon.

2. The P-51 Malcolm Hood, first installed in Mustang I AG 618 was an NAA Design/Malcolm manufactured canopy. 

From RAF AFDU/3/20/33 Dated 7 December, 1942

*"In accordance with instructions from Air Ministry (DAT) reference CS/11800, trials have been carried out on a Mustang IA aircraft, AG618 (sic: AG618 is actually a Mustang I - MV) fitted with a sliding hood. This hood has been designed by North American representatives in this Country and fitted to the aircraft by RAF Henlow, and is merely an interim measure in order to ascertain the tactical advantages of having a sliding hood on Mustang aircraft..."
'2. The aircraft has been flown at Duxford for 5 hours and the following comments are forwarded:
'Advantages 
'(i) The view for take-off and landing is considerably improved with the hood in the open position. Previously pilots have felt a trifle cramped when landing the Mustang fitted with the standard hood as the long nose restricts forward view and the view to the side panels is poor when compared to most British fighters.
'(ii) The aircraft has been flown at cruising and fast speeds with the hood open and the view for search was found to be greatly improved. Night flying was not actually possible on this aircraft as flame dampening exhausts were not fitted, but it is certain that the improved view would make this aircraft most suitable for night flying. 
'(iii) The view forward and sidewards is now completely unrestricted and this gives much confidence to pilots when flying in bad weather.
'(iv) It was found possible to fly with the hood open without using goggles, as apart from a slight eddy at the back of the cockpit, there is no draught.
'(v) With the sliding hood entry and exit from the cockpit is much easier. It was found with the standard hood that it was advisable for a Rigger to make quite certain that the hood was securely locked before taxying out and with the sliding hood tis was now unnecessary.
'(vi) the aircraft fitted with the sliding hood was limited from diving, but maximum level speed runs have been carried out without any problems developing. The hood, although only a lash-up model, showed no signs of blowing away and stayed in the open or shut position at all speeds. It is necessary to use both hands to open or close the hood even at at slow speeds and although at at first this was found a little difficult. it became reasonably easy after practice. The hood has been opened at an indicated speed of 250 mph and closed again at 300 mph, though at these speeds the opening movement was found rather difficult.
'(vii) Level speed runs have been made with this aircraft fitted with the standard hood and with the sliding hood. With the sliding hood there appeared to be a slight increase in speed which is probably due to removal of the aerial mast and rear ventilators. It was also compared with a standard Mustang from an Army Co-operation squadron and again showed a slight superiority in speed."
"Disadvantages
'(i) The radio mast has to be removed from its present position behind the cockpit to allow the hood to open. this will necessitate re-positioning the mast.
'(ii) There is a very slight up-draught through the cockpit when the inboard wheel fairings are open when operating the undercarriage, but this is not considered sufficient to worry about. [The next section concerned criticisms that only affected the 'lash-up hood' and so has been omitted.]
'Conclusions '3 The tactical advantages of being able toopen the hood of the Mustang in the air are very great and pilots have been most enthusiastic about the improved view, particularly during bad weather flying. This should be a great asset whn carrying out "Rhubarb" operations.
'4 The sliding hood will make the Mustang most suitable for night flying due to the view for search and night vision being greatly improved.
'Recommendations
'5 It is strongly recommended that as tactical advantages of having a sliding hood on Mustang aircraft have proved so great, a hood should be carefully designed and fitted to all Mustang aircraft as soon as practicable." 
*

Robert Malcolm, Ltd. was assigned the task of manufacturing the production kits. This firm specialized in blown Plexiglas and made the earlier Spitfire canopy among others. Malcolm refined the NAA design in several ways - notably the hand crank and forward locking system, and began production.

All Malcolm Hood canopies were installed in the UK after arrival. In the case of RAF, the Hood was installed prior to operational acceptance of ALL Mustang III's at RAF Henly, along with new antenna, etc. In the case of 8th and 9th AF the need was too great to hold up each P-51B/C for ~135 manhours to do the installation. 

For the 8th AF I believe that RAF/AAF Warton (not RAF/AAF Burtonwood) as it was the primary Depot for B-24s and P-51s and initially they did EVERY mod for the P-51 after assembly at Speke, including the original 85 gallon tank Inst'l in the P-51B-1 and -5-NA and C-1-NT's that were shipped to England. I still have not found source documentation for Hood installations at each fighter group base Service Group as kits became available. I doubt it simply because Warton would be better equipped and personnel trained in the installation rather than varied skills at different bases. 

The DFF fin mod was done first by RAF on a Mustang X, AL 963, in July 1942. It achieved measurable but not complete successful stability improvement. I have found no correspondence from RAF Hucknall to NAA detailing the results, nor internal documentation at NAA leading to the test and production design of a DFF nearly two years later. The structure in the rear empennage of the P-51B and D was strengthened by TO to compliment the addition of the DFF kits to P-51B/C and P-51D-5-NA through approximately 44-13980. Somewhere after that, the DFF was installed to the end of -5 and all succeeding D,K models.

I have seen a valid DFF on several 354FG ships including Beerbower's Bonnie B which is dated before mid July and a couple suggesting a much earlier install - but I haven't nailed the actual dates OR the place of Modification as the kits didn't arrive for 8th AF until late July at the earliest.

I must admit surprise that the myth of the 'Tyhoon canopy was installed on the P-51D prototype' continues to linger as the image of 43-12102 is well known and easy for the practiced eye to note the huge difference in shape.. ditto when comparing the Mustang to the P-47D bubble canopy - which IS much closer to the Typhoon canopy.


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## grampi (Apr 7, 2015)

Milosh said:


> Ah, was that to take photos of German fighters shooting down American bombers?



Lol!


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## pbehn (Apr 8, 2015)

It is a bit strange to me that the malcolm hood or a US version of it wasnt put on he Mustang from the start, since it was designed for the British and the Spitfire was already in service at the time, ditto for the P47 and F4U. Were there drawbacks to the Malcolm hood such as not being optically perfect?


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## drgondog (Apr 8, 2015)

pbehn said:


> It is a bit strange to me that the malcolm hood or a US version of it wasnt put on he Mustang from the start, since it was designed for the British and the Spitfire was already in service at the time, ditto for the P47 and F4U. Were there drawbacks to the Malcolm hood such as not being optically perfect?



Interestingly, VERY few Malcolm Hoods were retrofitted to Mustang I and IA even after the design and production ensued. I suspect that Malcolm Ltd had its hands full producing the canopy for the Spit and Mustang III and P-51B/C after the design was proven in service... 

The DFF was also first installed and tested with favorable results to improve yaw stability in the Mustang X, but somehow NAA didn't get the memo. Having said that the DFF was never THE solution for high speed yaw issues and only solved by the combination of longer fuselage, greater moment arm between a/c of wing to a/c of horizontal Stab plus 15% greater area of the horizontal Stab - of the P-51H over the B/D.

As Greg noted above, the increase in torque of the four blade prop plus the Rolls engine over the Allison was the root cause of the increasing issues as maximum HP grew from 1150 to 2200 from XP-51 to P-51H


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## fastmongrel (Apr 8, 2015)

There is a film on the net showing the manufacture of a bubble hood. I have looked but cant find it again but iirc correctly it was a very sklled and labour intensive process with a high percentage of rejects.


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## bobbysocks (Apr 8, 2015)

i wonder if it distorted depth perception when landing. back in the early 70s i tried a dome style face shield when riding motorcycles. while i loved the view ( and lack of bugs smacking my face ) the curves distorted things more than i liked so when to a flat shield. i could see that kind of hood might make assessing the distance off of the ground could be an issue.


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## pbehn (Apr 8, 2015)

bobbysocks said:


> i wonder if it distorted depth perception when landing. back in the early 70s i tried a dome style face shield when riding motorcycles. while i loved the view ( and lack of bugs smacking my face ) the curves distorted things more than i liked so when to a flat shield. i could see that kind of hood might make assessing the distance off of the ground could be an issue.



Reading the appraisal by the US an advantage of the Malcolm hood is it could be slid back for take off and landing. Some Spitfires have an oval panel in the hood sides. I remember reading this was optically perfect but cant remember why it was placed where it was, not all photos show it.


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## fastmongrel (Apr 8, 2015)

pbehn said:


> Reading the appraisal by the US an advantage of the Malcolm hood is it could be slid back for take off and landing. Some Spitfires have an oval panel in the hood sides. I remember reading this was optically perfect but cant remember why it was placed where it was, not all photos show it.



It was a Knockout panel that the pilot bashed with his elbow if the inside of the cockpit steamed up. It could also be used when trying to open the canopy in an emergency sometimes at high speed the pressure differential could make the cockpit stiff to move. I believe they stopped being fitted when the blown canopy with curved sides came into use on the MkVs.


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