Lockheed Model L-200 Convoy Fighter: The Original Proposal and Early Development of the XFV-1 Salmon - Part 1 by Jared Zichek

Author:Jared Zichek [Zichek, Jared]
Language: eng
Format: azw3
Published: 2017-06-22T04:00:00+00:00

Power Plant

A general arrangement drawing of the final power plant as proposed for the L-200-1 airplane is shown below:

The basic power sections were those of the Allison T-40A-8 engine as described in Allison Specification No. 272B, revised 31 May 1950. The power ratings of the engine used for the performance of the airplane were:

This engine was modified by changing the standard single speed gear box to a two-speed gear box with a larger offset between the power section centerlines and the propeller centerline. A discussion of the reasons for this additional offset was given under the previous Internal Arrangement section. Since this gear box was the subject of considerable discussion between BuAer, the Lockheed Company, and the Allison Company, a clarification of the gear box development program was obtained from Allison. As a result of this investigation, it was decided to use Gear Box No. 3 since its development time did not exceed that of the standard gear box with the two-speed unit and since it had a sufficient offset to improve the airplane arrangement in a major fashion.

Study of the power plant and aircraft accessories indicated that the most desirable accessory location would be on the front side of the gear box where all of the accessories for the airplane would be reached through external doors or through the duct closure doors. Since this location of accessories caused an additional development period on the gear box, it was decided to forego these advantages in the proposal and accept Gear Box No. 3 with the normal accessory positions on the aft side. Further study of this item was required during Phase I of any contract to determine whether the forward location of the accessories actually necessitated the additional gear box development time or whether the program of aircraft development could reasonably stand such a delay.

During the analysis of the airplane performance, a further discussion was held with the Allison Company and BuAer as to the feasibility and desirability of using an afterburner to eliminate the necessity of a two-speed gear box in the airplane, as shown below, or in addition to the use of the two-speed gear box. It appeared that the use of an afterburner would improve the high speed performance by approximately 13 kts without the two-speed gear box and 38 kts if both the two-speed gear box and afterburner were installed. These high speed advantages could only be obtained, however, with a weight empty penalty over the proposed airplane of approximately 435 lbs with the single-speed gear box or 635 pounds with the two-speed box. This included a weight penalty of approximately 498 lbs of fuel which was required if the afterburner was used for climb and combat. Only 282 lbs of this fuel could be conveniently carried. Lockheed recommended that this type of power plant also be considered in any Phase I study in order to determine whether or not the high speed advantage was worth this penalty and whether or not it was necessary to incorporate two speeds in the propeller gear box where an afterburner was installed.

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