Curtiss XP-42

History:


Let's face it, this aircraft was a dead end in the Curtiss fighter development line. The idea of building an aircraft derived from the Model 75 (whose airframe had considerable performance reserves), powered by a radial engine and matching the performance of fighters powered by inline engines, was born while the prototype Curtiss XP-37 was being tested. This aircraft was powered by an inline Allison, but its turbocharger was still rather a nuisance and it was at this time that the view could be, and was, promoted that by the time the Hawk 71 (Curtiss P-40), it would be advisable to produce a sort of bridging type with a radial engine, but cowled so closely that its aerodynamic drag would be comparable to an inline engine.


A fourth production aircraft was modified, the P-36A, and designated the Hawk 75S in late 1938. The modifications consisted mainly in the extension of the propeller shaft by 500 mm and this allowed to mount on the propeller a massive propeller cone, which was connected to the tight engine cowling, the work was successful in outline, but logically we then have the problem of engine cooling, in order to cool the engine sufficiently by air flow, a trap appeared under the engine and the upper part of the engine was cooled by enlarged holes in the machine gun covers. On 5 March 1939 the aircraft was handed over to the army pilots who immediately began to complain about the unbalance of the aircraft (500 mm extension in the front section), a quick solution was to load the rear section, but this in turn caused an increase in weight, and more weight inevitably leads to a decrease in performance. The maximum speed reached then did not exceed 505 km/h and in addition the engine was too warm. The aircraft therefore returned to the parent factory in Buffalo where it was modified by the Curtiss factory engineers, who worked closely with engineers from the Pratt & Whitney engine company. As a result, the lower trap was enlarged and the upper two after the machine guns were combined into one, slightly larger one. After only a few takeoffs, it was clear that even this cooling was not sufficient.


Blowdown in the NACA wind tunnel was to be of help. Several designs were made here, and all already had a common feature - they were at least minimally open in the front, and a fan provided forced airflow. The trials dragged on until late 1942, when it was clear to all that the XP-42, the military designation for the Hawk 75S, would not make it into production. Top speeds ranged from 544 to 553 km/h. Tests with engine covers were terminated with the knowledge that only a conventional open engine cover could provide sufficient airflow to keep the radial engine cool. The XP-42 continued to fly after the tests were completed, with floating tail surfaces being tested. Its career ended only in early 1947 - by scrapping.



Sources:
The Curtiss Hawk 75, Aircraft in Profile No. 80, Profile Publications, Ltd. 1966
Marek Ryś: "Curtiss P-36 Hawk"; AJ-Press 2002 ISBN 83-7237-057-5
Václav Němeček: "Vojenská letadla 3.díl"; Naše vojsko; Prague 1992
P.M.Bowers: "Curtiss Aircraft 1907-1947"; Naval Institute Press 1979
Profile No. 45 Curtiss Army Hawks-Peter M. Bowers-Profile year 1965
E.Angelucci and P.M.Bowers: "The American Fighter"; Orion Books NY year 1987
http://avia.russian.ee/air/usa/curtiss_p-42.html
http://www.aerofiles.com/_curtx.html
author's archive

Fotografie z různých etap zkoušek:
nahoře: první řešení
druhý obrázek: druhé řešení - zbraně jsou odstraněny
snímky dole: dvě verze z pozdních zkouček
www.geocities.com
http://avia.russian.ee/air/usa/curtiss_p-42.html
http://www.aerofiles.com/curt-p42tail.jpg
archiv autora

Náčrty pohled z boku na první a pozdější provedení. Zdroj: archiv autora

Pohled z boku na barevné provedení.