Curtiss P-40H 'Hisso-Hawk'

[apophenia]

Much of French combat aircraft production was hampered by limited engine supply. The AdA had stipulated that alternative, US-made engines installations be made available for all combat types. That proved a problem for single-engined fighters. The Allison V-1710-F was specified for some French fighters (such as the Arsenal VG 32) but this US engine was unable to accept French moteur canons which severely restricted armament options. As an expedient, the US government decided to fund production of French Hispano-Suiza engines in America. The model chosen was the Hispano-Suiza 12-89ter (later known as the HS 12Z).

With major US engine makers already engaged in war production, the challenge was to find a suitable manufacturer for the American-made Hispano-Suiza engines. After a Department of War review, it was concluded that spare capacity existed in Indiana. A decision was taken to resurrect the defunct Duesenberg Automobile and Motors Company of Indianapolis. Duesenberg had ceased auto production in 1937 [1] and, to many observers the choice seemed an odd one. However, Duesenberg had been a supplier of aero-engines to the US military in World War One.

The Indianapolis plant had been partly taken over by Marmon-Herrington which, by 1940, was busy producing 4WD conversion sets suitable for military use. However, MH was willing to share the space. [2] Production was slow to get established - in part due to tardy supply of sample engines from France, [3] in part because of 'Americanization' issues. The latter were bureaucratic delays in deciding whether to build engines to American standards (simplifying local parts and fastener supplies) or to tool up the Indianapolis plant to build to metric standards which was the preference of the French end-users. Air Corps interest in moteur canons clinched the deal - the Duesenberg engines would be 'Americanized'.

Both French and American authorities favoured the conversion of a Curtiss Hawk 75 airframe to test the Duesenberg engines. In the end, the USAAC provided an Allison-powered Curtiss P-40 (Model 81A) to simplify conversion. In June 1940, this airframe was fitted with a pre-production Hispano-Suiza 12-89ter and test flown by the end of the month. After trials at Wright Field, it was decided to order production versions - powered by Duesenberg V-2200 V-12s - for the USAAC. There was some debate as to whether the Air Corps 'motor cannon' types should be designated as attack aircraft or as pursuits. In the end, for continuity, they were designated as Curtiss P-40Fs (for US supply to France) and as P-40Hs for the Air Corps.

Top Prototype conversion Curtiss Model 81H/P-40H 'Hisso-Hawk' powered by a French-made Hispano-Suiza 12Y-89ter engine. Note the pointed spinner (this aircraft was unarmed) and prominent side-draft carburetor intakes.

The Curtiss intake design incorporated substantial dust filters. These would prove essential for operations in French North Africa. In Britain, these filters were sometimes removed to improve air flow.

The initial production Curtiss P-40H-CU-1 aircraft were to have been supplied as US aid to France. Both powerplants and armament were to be installed at Bases de Stockage for the Armée de l'Air. However, the French collapse thwarted these plans and no French 12Y-89ter engines were ever available during the War. Instead, P-40H-CU-1 airframes ended being completed with American engines and armament as P-40H-CU-2s. These aircraft had 1,300 hp Duesenberg V-2200 powerplants and were armed with a 20 mm motor cannon and four .30-calibre Browning machine guns. The 20 mm M1 Aircraft Automatic Guns were produced by the National Pneumatic Co., Inc. of Boston.

The first Hispano-Suiza Type 404 gun had arrived at the Aberdeen Proving Grounds in March 1938. A license to produce the guns in America had been arranged by the US State Department [4] but the  Ordnance Department stipulated that a substitute for waxing cartridges must be found before any substantial orders would be issued on behalf of the Air Corps. Once the Watervliet Arsenal tested the shorter chamber of British Hispanos, a tender was issued to selected firms. Contracts were then issued to Bendix Aviation and the National Pneumatic Co. to produce what was initially known as the .79 inch Aircraft Automatic Gun M1. Quickly re-designated as the 20 mm M1, National Pneumatic delivered the first motor cannons to the Air Corps. [5]

Bottom A production Curtiss P-40H-CU-2 'Hisso-Hawk' with cowling removed, revealing the 1,300 hp Duesenberg V-2200 engine, coolant radiators, and - directly in front of the cockpit - the drum magazine of the early M1 cannon.

The Curtiss P-40H was not ready for combat until after US forces had pulled back to the UK and North Africa. The 'Hisso Hawk's became famous for the carnage created amongst Italian columns retreating in Tripolitania. The type had proven itself but its key weapon - the 20 mm M1 cannon - was plagued with stoppages. As a field expedient, some P-40H-CU-2s were armed with .50-calibre Browning machine guns to fire through their propeller hubs. At one point, consideration was given to dumping the Hispano in favour of a licensed version of the 20 mm Madsen gun by Dansk Industri Syndikat of Copenhagen. [6] Fortunately, the major issues with the Hispano were solved when National Pneumatic devised a distintegrating-link belt-feed mechanism to replace the troublesome drum magazine.

With the improved M1A1 gun installed in the P-40H-CU-3, the rest was history ...
_________________________

[1] August Duesenberg continued building marine derivatives of flat-head Hudson straight-8s.

[2] At the W. Washington St. facility, Marmon-Herrington occupied the former 'Experimental Building' and Factory Building #3 while the revived Duesenberg Motors used Factory Building #2, 'B', and 'c'. Factory Buildings #1 (offices), 'D', and 'E' were shared spaces.

[3] These delays appear to have originated with the French Bureau de Cessions de Materiel a l'Etranger which initially denied requests for export permits on the grounds that French military aero-engine developments were considered state secrets.

[4] The Bendix Aviation Corporation had earlier tried to negotiate a license to produce Type 404s for the US Navy. This was not successful.

[5] The Elmira, NY-based Eclipse Machine Division of Bendix Aviation would produce M1 guns for the US Navy.

[6] This got as far as the Mergenthaler Linotype Co. producing 'sample guns' but no license agreement could be reached with US representatives of DIS/Madsen (the parent firm being .

[Empty Handed]

Subtle difference on the 81H profile. I like it.

Never occurred to me to put a 12Z in an American aircraft. Makes sense for American production for France but at first glance, less-so for US-own aircraft but if, as in the GB premise, the US were a little wrong-footed by their early entry into the war and the production juggernaut hadn't spun up yet, I could see them taking whatever they could get.

[Robomog]

Now that's one fine looking aircraft !

Always amazes me how you come up with the the detailed history 

Mog
>^-.-^<

[Brian da Basher]

Wow what a stunner! I love how you represent natural metal finishes, apophenia! Nobody does it better!

I'd enjoy seeing that olive drab version with the engine buttoned up. It's probably the kid in me but I always like to see them like they're in flight.

Most outstanding and as always, a feast for the eyes!

Brian da Basher

[apophenia]

Thanks folks!

...I'd enjoy seeing that olive drab version with the engine buttoned up...

Here at Apo Aviation, we aim to please. Some folks prefer their models completely draped. That's a question of individual taste -- leaves more to their imaginations   So, some operational 'Hisso-Hawks' ...  As already mentioned, the P-40Hs were delivered to USAAC units in both Britain and French North Africa.

USAAC P-40H-equipped squadrons were grouped along the southern and south-eastern coast of England. Initially, the P-40s focused on invasion barges and other craft being positioned for Germany's Unternehmen Seelöwe (Operation Sea Lion). The easternmost of the P-40H units was 61st Pursuit Squadron (Attack), stationed in Suffolk. The 61st PS gained a reputation for effective attacks on heavily-armed Schnellboots in the Channel. Later, these E-boats were pursued into their harbours and other land targets attacked. These raids into the Low Countries, the P-40Hs often acted in concert with twin-engined A-20 Havocs - attack aircraft in their own right but also helpful with navigation for the single-seaters in clagged-in weather.

(Top) A P-40H-CU-4 'Hisso-Hawks' of the 61st PS(A), 56th FG, 8th AF, out of Halesworth. Note British A1-style yellow roundel surround, six-position cockards, and 'hi-viz' tail stripes. Also note the simplified carb intakes (without bulky filters).

All P-40Hs assigned to North Africa mounted the vital sand filters. Most were delivered to Morocco in Olive Drab over Medium Gray scheme. These were then overpainted in-theatre with Sand 26 - either in contrasting panels or in random blotchings. Undersides were often re-painted in locally-available Bleu pâle. The final deliveries of P-40H-5s arrived in French North Africa in all-over 'Desert Pink' (although some had Bleu pâle undersides applied in-theatre).

(Bottom) Curtiss YP-40H-CU-3 trials aircraft, 45th Pursuit Group, flying out of Kairouan in northern Tunisia. This aircraft's badly-faded OD uppers have had blotches of Sand 26 applied over top. No unit markings have been applied (the question mark being a local affectation).

The YP-40H-CU-3s were all rebuilt P-40H-CU-2s armed with 23 mm Mergenthaler XM5 cannons (an unlicensed copy of DIS Madsen samples). In all respects other than cannon type, the YP-40H-CU-3s was identical to the P-40H-CU-2. However, note that this particular aircraft also has a plumbed belly rack for a long-range fuel tank. As shown, this YP-40H is being flown with its canopy open - always tempting for low-level flights in hot climates (with the added bonus of quickly clearing the cockpit of any gun-firing fumes).

The 'Hisso-Hawks' served their purpose but were phased out of production after the P-40H-CU-5s. The Allison-powered P-40Ks with their twin wing cannon armament eliminated the
raison d'être for the 'Hisso-Hawk'. Once the final V-2200-3 motor-cannon engine was delivered, Duesenberg became a components supplier for the Packard Merlin program, but that is another story ...

[Brian da Basher]

Wow talk about gorgeous! You really show your talent with the mottled camo on the bottom one, apophenia!

Absolutely delightful!

Not only that, but entirely plausible too!

The question mark code was a nice touch.

These could be my favorite planes without spats.
 
Brian da Basher

[elmayerle]

Beautiful and plausible; I quite love the way your imagination works in conjunction with excellent artistic skills.

[finsrin]

Absorbing technical story about getting things sorted out.  Certainly looking good too. 

[GTX_Admin]

 

[Geoff]

Excellent!

Staring at an Airfix Tomahawk as I type.

[Old Wombat]

I like 'em!

[Kelmola]

Considering the Klimov M-105 was a derivative of the earlier HS 12Y engine, and the Soviets re-engined a few P-40's (and even some P-39's) with those, there's almost a historic precedent for this

[apophenia]

Ah, nice one Kelmola     I'd completely forgotten about the P-40s re-engined with M-105s ... but I'd never heard of Klimov-powered P-39s! That would be one hell of an engine swap 

[Geoff]

I wonder what one of these would look like in Vichy markings? Hmmm!