The F-109 Designation

RyanC

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Well, we know from Andreas' Parsch's excellent site

Link

that

This designation is usually attributed to the Bell Model D-188 supersonic VTOL fighter project of the late 1950s. However, while Bell and/or the ARDC (Air Research and Development Command) twice requested the YF-109 designation for this project (in January and October 1958), both requests were officially turned down by HQ USAF.

A few years earlier (most likely in 1955), F-109 was also requested for the two-seat interceptor version of the F-101 Voodoo (which became the F-101B in the end). However, this request (which is somewhat inexplicable anyway, because the next number in line at that time was F-108) was apparently cancelled at an early stage, because no written documentation about it exists in USAF nomenclature records (the only available first-hand source is a preliminary "Standard Aircraft Characteristics" sheet). Still other reports link the F-109 designation to a proposed operational version of the Ryan X-13 Vertijet VTOL demonstrator, but there is no firm evidence available for this claim.

All said, F-109 was never officially allocated to any fighter project.

Copies of the Disapproval Notices obtained from I believe, Andreas Parsch's website are attached to this post; and I've provided transcripts of them.

STATUS OF USAF EQUIPMENT
ADDITIONAL INFORMATION

DATE
29 January 1958

FILE NUMBER

1. NAME OF NEW ITEM
(U) Aircraft, Fighter Bomber, YF-109

NAME OF OLD ITEM
Initial Request

2.

a. This is a request for the initial Air Force model designation for the Bell VTOL Fighter/Bomber, presently under Phase I Navy Contract.

The authority for this project is ARDC.

This program will be a Joint Air Force/Navy development project, funded on a 50-50 basis.

b. The YF-109 (tentative) is a single phase, Vertical Take-off and Landing (VTOL) fighter-bomber powered by eight (8) J-85's. The YF-109 will be approximately 55 feet long, have a wing span of about 24 feet; and weight about 23,000 pounds.

c. Present planning calls for the manufacture and flight test of three (3) prototype (YF-109) models in 1960, with subsequent production and delivery of F-109's in the 1962 plus time period. The F-109 will be utilized by the Tactical Air and Theatre Commands.

3. The Navy has designated subject aircraft the F3L and since the Air Force has already matched Navy funds expended on this program, designation of the YF -109 is justified.

Model Designation Disapproval by HQ USAF
(ILLEGIBLE) 14 Feb 58.

STATUS OF USAF EQUIPMENT
ADDITIONAL INFORMATION

DATE
3 October 1958

1. NAME OF NEW ITEM
(U) Aircraft, Fighter Bomber, XF-109

2.

a. This is a request for Air Force model designation for the Bell VTOL Fighter/Bomber, presently under Phase I Navy Contract. The authority for this project is ARDC.

b. The YF-109 (tentative) is a single phase, Vertical Take-off and Landing (VTOL) fighter-bomber powered by eight (8) J-85's. The YF-109 will be approximately 58 feet long, have a wing span of about 24 feet; and weight about 25,000 pounds.

c. Present planning calls for the manufacture and flight test of three (3) prototype (YF-109) models in late 1960 and early 1961, with subsequent production and delivery of tactical F-109's in the 1962 plus time period. The F-109 will be utilized by the Tactical Air and Theatre Commands.

3. Present schedules call for completion of Phase I in February 1959; however, Phase II go-ahead will be needed prior to this date. Programming for this aircraft will be based on WA-58-2 under FX (V/STOL).

Disapproved
HQ USAF
6 Feb 59

Yet, when it came time to designate the F4H Phantom II in the USAF series, it was assigned the designator F-110A Spectre, instead of F-109A Spectre. So what's with the skipping?
 

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Andreas Parsch

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RyanCrierie said:
Yet, when it came time to designate the F4H Phantom II in the USAF series, it was assigned the designator F-110A Spectre, instead of F-109A Spectre. So what's with the skipping?
I don't know the final answer to this question, and I think that apart from those who "were there" at the time, nobody knows ;).

What I do know, though, is that the USAF apparently had no fixed policy about skipping of disapproved or cancelled designations. E.g., the original designations C-137 (YC-137 became YC-97H), F-104 (XF-104 became XF-98A) and F-106 (XF-106 became XF-84H) were all cancelled and their numbers later re-used for other projects (twice in case of C-137!). On the other hand, in the Q-series of target drones, the requests for slots Q-7, Q-8 and Q-11 were disapproved and the numbers not used afterwards. Another disapproved and non-reused slot is C-139.

One might think that a number is re-used, if it is still the next-in-line when a new request for designation comes in (i.e., the disapproval process has not taken so long that the following number in the series has already been assigned). This is a policy which was sometimes followed by DOD for the post-1962 joint system. But there are several counter-examples for this in pre-1962 USAF allocations - e.g. the F-106 gap was refilled with F-106A in 1956, while the F-107A designation had been allocated in mid-1954!

Things get even more complicated, because there was apparently a very short-lived (~ 1954/55 time frame) USAF/Navy agreement, that the Navy would use even-numbered slots in some (or all??) USAF designation series. Because the idea never took off, it led to gaps for at least H-36/38 and C-134/136/138. Some of the gaps were later filled by more or less "open" projects (C-134/136), some by very obscure ones (H-36/38), and C-138 remained unassigned. There is circumstancial evidence that the "even-numbers-for-Navy" scheme was briefly applied to the F-series as well:
- When F-107A was allocated in 1954, the F-106 slot should have been available, because I think the XF-84H had been redesignated by then (however, I can't find hard evidence for this right now).
- A McDonnell proposal for a two-seat interceptor version is labeled "F-109". The proposal must be from around 1955, when the F-108 slot was definitely not yet assigned.

Anyway, all this might be interesting (or not ;D ), but doesn't directly address your question about the F-109 ;). Well, I guess(!) that the skipping of F-109 has something to do with the "visibility" of Bell's effort to have the F-109 designator approved. Other cancelled designations like XF-106 etc. were very short-lived and probably not widely known throughout the Air Force, let alone the general public. On the other hand, as far as I know Bell openly used the F-109 designation even though it hadn't been approved by the Air Force. So maybe the idea "F-109 = Bell D-188A VTOL" had been spread a bit too much, so that it was deemed confusing if the F-109 slot would be used for a completely different projects later.

An alternate explanation would be a change in general policy from "fill the gaps" to "always advance to next number" around 1960 or so. Supportive evidence for this are the designations C-140 and Q-12, which were allocated in 1960 or later. In both series, the preceding number had been disapproved, was therefore available for allocation, and was definitely not "well-known" in any sense of the word (in fact, I never saw SC-139 and XQ-11 anywhere before they turned up in my own research :eek: ).


So, bottom line is ... I don't know why the USAF Phantom didn't become the F-109A - but I sure can speculate about it ad nauseam! ;D
 

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