P-51 Mustang
‘C to ‘D
From
hen I was asked to write about the differences between the P-51C Mustang and the considerably more numerous D-models I thought that a fun way of doing it would be for you, the reader, to pretend that it’s June 1944. Although you’ve you’ve just arrived in
W
Top right
‘FlyPast’s resident warbird pilot Dave Unwin in the front seat of P-51C ‘Betty Jane’. Above
An air-to-air view view of ‘Betty Jane’ with Dave Unwin in the rear seat. ALL BE TTY J ANE PIC TURES BY JIM LA WRENC E
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England expecting to be posted to a P-47 Thunderbolt squadron, as sometimes happened you you’ve ’ve been sent to a squadron that is equipped with both ’C and ’D Mustangs. Mustangs. I’ve been detailed to brief you on the differences between the two. With only about four hours hours in Mustangs in my logbook I’m not exactly an expert, but at least I have flown both models and there’s many Mustang ‘drivers’ who’ve who’ ve never flown flown a ’C. I was introduced to the P-51 by Jim Harley, who has
over 1,400 hours in both versions, so I had a good teacher!
Canopies and guns Let’s take a look at a couple of ships Let’s sitting out on the ramp. Even from a distance it’s obvious which one’s which – the P-51D’ P-51D’ss big bubble canopy is very different from the multi-pane arrangement of a ’C – that wouldn’t look out of place on a Luftwaffe machine. It follows that the field of view from a ’D is lot better than that from a ’C. Once you’ve flown a ’D you really won’t want to go back to a ’C. That’s why most of the old hands in this outfit are flying
Dave Unwin highlights
the differences between the Mustang’s C- and D-models
P-51 Mustang
P-51Ds, and why as a ‘newbie’ you’ll almost certainly start off in a ’C. Still, you never know your luck. North American is really cranking them out these days – some say as many as 40 a week and it won’t be long before all the ’Cs are retired. Another reason most combat combat pilots prefer the ’D is that it’s got 50% more firepower. They are the same type in both – 50-calibre Colt-Browning M2 machine guns mounted in the wings – but where the ’C has four, with 350 rounds each for the inner guns and 280 for the outboards, the ’D has six, with 380 rounds for each of the inboard pair and 270 each for the outers. Now, here’s something you may not know… the wing bays on the ’D are slightly deeper, which allows the guns to be mounted mounte d vertically. Overall this is good as they’ t hey’re re less prone to jam, but the thicker wing has knocked a few knots off the top speed.
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Packard Merlins
The engines are essentially the same; Rolls-Royce Merlin V-12s, built under licence by Packard with the USAAF designation V-1650. As delivered from the factory, the ’C uses a V-1650-3 (or ‘Dash 3’) and the P-51D a ‘Dash 7’, but out here in the field it’s not uncommon to find a ’C fitted with a ‘Dash 7’ and a ’D with a ‘Dash 3’ – there is a war on you know! The ‘Dash 3’ produces up to 1,490hp (1,111kW) at 3,000rpm and the ‘Dash 7’ an extra hundred. These engines feature two-speed superchargers and two points you might want to bear in mind is that the Merlin is liquidcooled
“Once you’ve flown a ’D you really won’t want to go back to a ’C. That’s why most of the old hands in this outfit are flying P-51Ds, and why as a ‘newbie’ you’ll almost certainly start off in a ’C” and is a lot more powerful than the air-cooled radial fitted to the T-6 Texan you trained on. So be careful with that throttle – particularly at low airspeeds. You wouldn’t bang the stick around would you? Well, Well, don’’t bang the throttle around don either! Interestingly the Spitfire IXs flown by the RAF boys are also powered by Merlins, and the two types have broadly similar performance, handling and firepower. However, clever engineering gives the Mustang more than twice the internal fuel capacity of a Spitfire, which greatly increases its range. Furthermore, as the P-51 was the first production aircraft to be fitted with a laminar flow aerofoil section, the drag is greatly reduced, extending the range still further. The introduction of drop tanks means that Mustangs can escort USAAF B-17 Fortresses and B-24 Liberators deep into Germany.
Stability You might’ve You might’ve noticed that the leading edge of the C-model’s fin where it joins the fuselage is very different to a
’D’s. The latter design has a small ’D’s. dorsal fillet, and there are opposing points of view regarding its origin. Some sources state that it was installed to stiffen the tailplane, while others claim that when North American began fitting bubble canopies to ‘razorback’ fuselages, company test pilots soon encountered a problem – reduced directional stability. stability. In extreme cases, this lack of directional stability could also produce the dangerous condition of ‘rudder overbalance’. However,, the bubble canopy However provided such a significant improvement in visibility that North American knew it had to be retained. So company engineers simply increased the keel area aft of the centre of pressure by installing the dorsal fillet – problem solved! Nevertheless, the C-model still feels directionally more stable than a ’D. If you look at both in profile it’s it’s obvious why – there’s a lot more keel aft of the cockpit with a ’C. Note that
the elevators and rudder are fabric covered, but the ailerons are metal. All the control surfaces are fitted with pilot-operated trim tabs.
Landing gear The D-model’s main undercarriage is slightly different. The clam shell actuator was moved from the front of the gear well to the rear, the up-locks were redesigned and I’m pretty sure the hydraulic lines were placed differently as a result. These changes added an additional fillet forward of each of the wheel wells, creating a distinguishing ‘kink’ and increasing the wing area slightly slightly.. The main gear has a reasonably wide track, as it retracts inwards, and the tailwheel also retracts. The gear is actuated hydraulically,, as are the hydraulically brakes and large slotted flaps.
Clockwise from below
North American P-51D Mustang ‘Crazy Horse’ is operated by Stallion 51. See page 56. The distinctive bubble canopy on the D-model. P-51C ‘Betty Jane’ taxying - poor visibility means that ‘S-turning’ is essential. The cockpit of ‘Betty Jane’.
P-51 Mustang
Drag-cutting Meredith Above
North American P-51D Mustang ‘Slender, Tender & Tall’. Below right
View of the control panel from the rear rear seat of P-51D N351DT ‘Crazy Horse 2’.
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Step inside Let’s take a look at the cockpit. I think we’ll use a C-model for this, as I doubt you’ll get a ’D just yet. It’s a bit of climb up to the cockpit, but it isn’t too difficult, thanks to several welllocated handholds and ‘kick-in’ steps. OK, sit yourself down. The pedals adjust and it’s very important that you’re comfortable – Berlin and back can be an eight-hour flight. flight. This ’C has the old N4 gunsight, if you’re lucky enough to be given a D-model you’ll see that it has a K-14 gyro gun sight, which is a lot better. The seat also feels a bit more ‘upright’ in the ’D, although it’s still very comfortable. You’re also a bit closer to the panel in the ’D and the glareshield covers more of the panel than in the ’C. The stick and tall throttle both fall nicely to hand, while the prop and mixture controls are mounted adjacent to the throttle, with the trim wheels, wheel s, flap and unde undercar rcarriag riagee levers levers underneath. There are a lot of circuit breakers on the starboard side, but luckily most of them are forward of the elbow line. As you you may rem remembe emberr from from some of the other North American aircraft you’ve you’ ve flown – such as the t he T-6 T-6 – although at first glance it looks a bit cluttered, closer inspection reveals that it is actually reasonably well designed. Various systems and sub-systems are all laid out logically. The fuel gauges (there are three tanks) are mounted in the floor. This feature has probably caused more than a few accidents, because although
September 2016
An interesting feature of both the P-51C and the P-51D is the infinitely variable outlet for the cooling system. This device played a pivotal role in the Mustang’s success, success, as it made use of a phenomenon known as the ‘Meredith Effect’. In very simple terms, by varying the outlet of the cooling system and forcing excess air through it at high speed, substantial back pressure builds up behind the radiator radiator,, and the additi onal thrust generated helps offset the drag caused by the radiator.
“Once you’re over the numbers fully close the throttle and hold the Mustang just above the runway. Let the tail sink slightly, then hold that attitude and let it land mainwheels first... fi rst...” ”
the maximum internal fuel capacity is 180 gallons (466 litres), the rate at which whic h itit is is consum consumed ed vari varies es wid widely ely.. For example, with the power pulled right back to the best economy setting of 1,800rpm the fuel consumption drops to around 36 gallons per hour. However, at the full military power setting of 3,000rpm and 61in of boost it rockets to 155 gallons per hour. Something else you might want to remember is that the 85 US gallon fuselage tank wasn’t part of the original design, but was added from the C-model onwards. It’s behind the cockpit, and when it’s full, the longitudinal stability is – shall we say – relaxed, so always empty this tank first. Drop tanks come in two sizes; 75 and 110 gallons. With a pair of the big tanks, the range is over 2,000 miles (3,218km). Unlike the elegant one-piece bubble of the P-51D, the C-model’s is a much more cumbersome affair. An interlocking clam shell design, it consists of four separate parts (not counting the windscreen). To close the two sections of the canopy, you first raise the lower half, which is hinged to the sill, into position, then lower the top half into place and lock it. Furthermore, with the clamshell canopy closed up you can’t even stick your head out of the side. When you’re on the ground in the ‘threepoint’ attitude the view forward is very poor because of the long cowling, so ‘S-turning’ is essential. Just Ju st like like on a T-6, the tail tailwhee wheell steer steerss through the rudder pedals up to about 6° either side if the stick is held back
past the neutral position. By pushing the stick forwards, which unlocks the tailwheel and allows it to castor, differential braking can be used for tighter turns.
General handling Starting is pretty straightforward, just make sure you don’t over-prime the motor, or you’ll get a ‘stack fire’. Don’t Don’t taxi too fast. For take-off correct use of the rudder trim is very important. The flaps are usually left ‘Up’, although if runway length is an issue, up to 20° can be used. Bring the power in slowly. As you pass 50 knots, gently pick up the tailwheel and increase power. Keep it straight. As you’ll discover, the noise is phenomenal. With the wheels in the wells, reduce power to 2,700rpm and 46in of boost – best climb is 170 knots and 3,000ft per minute. First thing I’d suggest is climb straight up to at least 10,000ft (around 3,000m). Try a couple of stalls and then acquaint yourself with the general handling. Remember we talked about the laminar flow wing? Well, that and a relatively high wing loading means that although the stall is preceded by some pre-stall buffet, when the wing does quit flying – it just quits! There’s also a pretty abrupt wing drop, and although it’ll start flying again once the wing is unloaded, you’ll lose several hundred feet in the process. The primary controls are powerful and although any out-of-trim condition produces forces that are
quite high, they are easily trimmed out. Once trimmed, it’s positively stable about all three axes. Harmony of control is good, with the ailerons being the lightest and the rudder the heaviest heaviest.. Remember though, the slip ball needs to be monitored constantly and the rudder trimmed often. Both models fly pretty much the same, although the ’D is marginally less stable directionally. Try Try some loops and rolls, but only while you’re up high. You need to use the rudder a lot; this is very much a ‘rudder airplane’ and – as you’d expect from a propeller that weighs hundreds of pounds and has a diameter of almost 12ft, there’s no shortage of gyroscopic precession. Rolls to the left are noticeably easier. There are two things you really want to bear in mind. Pulling hard into the buffet is likely to make the Mustang flick into an accelerated stall and depart from controlled flight. Once the nose is well below the horizon it really accelerates and at high altitude you can run into compressibility.
Touchdown OK, now you’ve learnt how to fly the thing, all you have to do is land it! On the downwind leg set the prop to 2,700rpm, drop 20° of flap, wait until the speed bleeds back below 150 knots and then lower the gear. On base leg stick another 10° of flap down and bleed the speed back to 130. As you turn onto final, flaps to 40° and speed back to 120. You want abou aboutt 100 100 over over the fenc fencee in in a C-model; in a ’D you can bring it back to between 90 and 95 once you’ve got some experience. Once you’re over the numbers fully close the throttle and hold the Mustang just above the runway. Let the tail sink slightly, then hold that attitude and let it land mainwheels first, followed by the tailwheel. It’ss neither a ‘wheeler’ nor a ‘threeIt’ pointer’, but is easily the best way to consistently achieve good landings in a P-51. A full-o full-on n ‘whee ‘wheeler ler’’ means means a faste fasterr touchdown speed, while a ‘threepointer’ can be fraught due to the stall characteristics of the laminar flow wing. Putting the wheels on the ground is very much a ‘two-stage affair’. It’s a bit like an old man sitting down in a chair. Well, W ell, that that’’s itit – now you kno know w as as much as me. If I were you, I’d go talk to the line chief about which Mustang’ss yours. Then get Mustang’ g et some practice in – you’re going to need it!
Left
Stallion 51’s 51’s Mustangs are based in Kissimmee, Kissimmee, Florida.
WW2 DESERTER OR PATRIOT? P-51 Mustang
Mustangs Marks
A - M
Depicting the changing profile of the P-51 Mustang over the years, artist Ted Williams presents pres ents a series of colour side views
A-36 - Named the Apache was basically a P-51A with dive brakes. ‘Priscilla’ ‘Priscilla’ was was flown by Lt. Lt. Bert Benear, Benear, 526th Fighter Squadron, 86th FB, USAAF.
P-51A - ‘Betty Lou’ served with the 68th Observation Group, Tactical Reconnaissance Squadron in Italy, 1944.
P-51B - ‘Ding Hao!’ was the personal mount of Maj James Howard CO of the 356th Fighter Squadron, 354th Fighter Group, 8th Air Force, USAAF. Based at Boxted, 1944.
P-51B - ‘Jesse James’ served with the 374th Fighter Squadron, 361st Fighter Fighter Group, 8th Air Force, Force, USAAF USAAF,, at Bottisham, England 1944.
P-51B - ‘West by Gawd Virginian’ was flown by Capt Robert ‘Punchy’ Powell of the 486th Fighter S quadron, 352nd Fighter Group, 8th Air Force, USAAF. The group was known as the ‘Blue Nosed Bastards from Bodney’. Based at Bodney Bodney,, England 1944.
P-51C - ‘Berlin Express’ was flown by Lt Bill Overstree Overstreett of the 363rd Fighter Squadron, 357th Fighter Group, 8th Air Force, USAAF, Lieston, England 1944.
P-51D - ‘Detroit Miss’ flown by Capt Urban Drew with the 375th Fighter Fighter Squadron, 361st Fighter Fighter Group (‘The Yellow Yellow Jackets’), Jackets ’), 8th Air Force, Force, USAAF. USAAF. Capt Drew was was the first pilot to shoot down a Messerschmitt Me 262 jet fighter.
P-51D - ‘Lois Honey’ was flown by Capt Douglas Benedict of the 55th Fighter Squadron, 20th Fighter Group, 8th Air Forc Forcee USAAF stationed at Kingscliffe, England 1944.
F-6D - ‘You Cawn’t Miss It’ was a Photo Recon variant of the P-51D flown by Lt Elmer Pankratz with the 160th Tactical Reconnaissance Squadron, 363rd Tactica Tacticall Reconnaissance Group stationed at Beuvachain, Belgium, 1945.
P-51D - ‘Miss America’. With a paint scheme created to emulate that of the USAF Thunderbirds, ‘Miss America’ has been an entrant at the Reno Reno Air Races for for many years. This is but one of the many P-51 Mustangs that have been resurrected resurrect ed and rejuvenated rejuvenated for air racing. racing.
P-51F - The F variant was an attempt to create a ‘lightweight’ Mustang. The result was a fighter 1,600lbs lighter than the P-51D. P-51D. Although a small number were were built and extensively extensively tested none were were put into production.
P-51H - The H-model was the final production Mustang. Although it had more power power and many refinements refinements it was only mariginally faster than the P-51D. This aircraft was assigned to Col Dave Schilling’s 56th Fighter Group stationed at Selfridge Selfridge Field, Michigan, 1946.
P-51K - ‘Fragile But Agile’- Flown by Lt Bert Lee of the 342nd Fighter Squadron, Squadron, 348th Fighter Group stationed stationed at San Marcelina Field, Field, Philipines 1945.
Mustang IVA (P-51K) - ‘Edmonton Special’ flown by Plt Off John Mallandaine, No.442 No.442 Squadron, Squadron, Royal Canadian Canadian Air Force.
P-51D - ‘Roto-Finish Special’. This highly modified P-51D with clipped wings and a cut down canopy was the winner of the 1972 Unlimited Championship flown by Gunther Balz at Reno, Nevada. Nevada.
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Mustang III (P-51B) - RAF Squadron 259, Italy 1944. 1944. Note the early application of a dorsal fin that appeared on later P-51Ds.
P-51B - ‘Shangri La’ was the personal mount of Capt Don Gentile of the 336th Fighter Squadron, 4th Fighter Group, 8th Air Force, USAAF. Based at Debden, England, March 1944.
P-51D-5-NA - ‘Cripes A’ Mighty’ was the personal mount of Maj George Preddy of the 487th Fighter Squadron, 352nd Fighter Group, 8th Air Force, USAAF stationed at Bodney, England 1944.
P-51D - Belligerent Bets’ flown by Maj Herschel ‘Herky’ Green of the 317th Fighter Squadron (‘Checkered Tail Tail Clan’), 325th Fighter Group, 15th Air Force, USAAF, Lesina, Italy, April 1944.
P-51D-30-NA - Personal aircraft aircraft of USAF Col Dean Hess, CO of Project ‘Bout One’, 51st Provisio Provisional nal Fighter Squadron, Republic of Korea Air Force.
P-51D - ‘Ole Yeller’. This aircraft was personally owned and operated by legendary air show pilot Bob Hoover. Called the “pilot’ss pilot”, Bob Hoover thrilled air ahow audiences for “pilot’ many years with his revolutionary revolutionary aerobatic aerobatic routines. routines.
P-51H - Too late for combat in World War Two, the H-model was sent to serve in Air National Guard units in 1946. This Mustang served with the Massachuset Massachusetts ts Air National Guard Unit at Logan Field, Boston, 1951.
P-51J - Another attempt at a designing a lighweight Mustang powered with the lastest Allison V-1710-119. The project was eventually eventually dropped. dropped.
Top
The NA-73 prototype. ALL BY TED WI LLIAM S
Cavalier II - Cavalier Aircraft Corporation optimized existing F-51Ds for export. The Cavalier II was designed for close air support and counter-insurgency counter-insurgency operations. operations. This example example was part of a group sold sold to El Salavador in 1968. 1968.
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