Lockheed L-/CL- Temporary Design Number (TDN) designations

[Dynoman]

Lockheed-California unsolicited proposal description for Quiet Aircraft page 95.

 

[overscan (PaulMM)]

It's the CL-1257 STARS, terminated in mid-1972. Front half of a T-1 with large span slightly swept wings and a new rear fuselage. Some details and a 3 view in Bill Slayton's unpublished monograph.

It was an unsolicited proposal but was looked at favourably by the USAF Prototype Study, making the shortlist:

Advanced Medium STOL Transport,
Very Low Radar Cross Section (RCS) Vehicle,
Large Tanker Aircraft,
Small Lightweight Fighter Aircraft
Quiet Aircraft
Remotely PilotedVehicle (RPV)

Ultimately it didn't get funding.

 

[hesham]

By the way,

from more than 10 years,there is a site which mentioned Lockheed CL series,from beginning up to CL-2000,just names,
and if you wanted to know any Infos,you had to contact them,I will try to remember it ?.

 

[hesham]

There is very important note,

that,we find two different series of Lockheed "CL",the first we know it as a completing to L sequence
which was started from L-100 ad almost switched in CL-257,up to CL-2000s,and the second was only
in-house of the firm,and it didn't relate to previous one

 

[hesham]

There is very important note,

that,we find two different series of Lockheed "CL",the first we know it as a completing to L sequence
which was started from L-100 ad almost switched in CL-257,up to CL-2000s,and the second was only
in-house of the firm,and it didn't relate to previous one

To confirm what I said,please read this.

 

[overscan (PaulMM)]

Nope. One designation system for CL.

Source?

 

[hesham]

My dear PaulMM,

it's not my words,it's by Mr. Jay Miller who said that in the book, The X-Planes X-1 to X-29,and also I have many proofs on it,beside this book.

 

[hesham]

Hi,

CL-720 was a single place helicopter,developed from XH-51,may a project
CL-873 was a Royal Netherlands Navy ASW Helicopter

Albert Yackle papers

 

[overscan (PaulMM)]

To confirm what I said,please read this.

It doesn't support what you said. ALL CL- designations are in-house.

The Temporary Design Numbers, hereafter referred to as TDNs are a series of numbers that are used to designate a particular preliminary design effort.

The TDN system was started in 1939 with L-100. Somewhere in the mid L-260s or so in late 1953 or early 1954, the prefix C was added to designated the California Company.

There were some designations used out of sequence or duplicated but this isn't because of another designation system.

 

[hesham]

It doesn't support what you said. ALL CL- designations are in-house.




There were some designations used out of sequence or duplicated but this isn't because of another designation system.

In reply # 125,there is a clue by Mr. Jay Miller,that means; CL-900,CL-901,
CL-902,CL-903 up to CL-1600 were allocated twice,we speak about 700
designations,whatever it's only my speculations by this great numbers,
and you could be right.

 

[overscan (PaulMM)]

I see what you are saying, CL-900 to CL-1600 = 701 numbers. The quote you gave is from Jay Miller's X-Planes book I think?

X-Planes 1983 Edition

Over a period of several years, a large number of design studies were generated by Johnson and his noteworthy engineering team. The various design designations included the series CL-900 up to at least CL-1600—some 700 studies in all!

X-Planes 1988 Edition

Clarence L. ‘‘Kelly’’ Johnson, during mid-1961, initiated an inhouse study effort to create a vastly improved, yet remarkably unchanged F-104.
[..]
Over a period of twenty-four months, some 700 design studies, assigned in-house Lockheed designators from CL-900 to CL-1600, were generated by Johnson and his famous ‘‘Skunk Works”’ engineering team. Numerous single- and twin-engine configurations were explored, with every one being
analyzed for its commonality with the F-104 and its relative performance improvements.

In his 1995 Lockheed Skunk Works book we have something quite different.

Over a period spanning some twenty-four months, numerous design studies, assigned Lockheed Temporary Design Designations CL-900 to CL-1200, were generated by the Skunk Works engineering team at Burbank. Numerous single- and twin-engine configurations were analyzed for their F-104 commonalty and relative performance merits.

As far as I can see, none of this is entirely correct.

from mid 1961 we have CL-901, then there are several other "F-104 developments" in the CL-900 series. Within the Lockheed TDN system, generally alternate designs are numbered with suffixes. So, there were 21 known versions of CL-901 -1 up to -21.

The CL-1200 is first used in mid 1969 for a VG Navy "VAM" study, but 29 December 1969 it is noted Lockheed Skunk Works division have taken this TDN for an advanced F-104 derivative and so the VAM work is continued under CL-1253.

The Skunk Works then uses CL-1400N (Navy CL-1200) and CL-1600 (LWF CL-1200) TDNs. CL-1400 was used for an AX study while CL-1600 was a L-1011 TriStar Twin study in 1973. Note that CL-1401 - 1499 were bulk assigned to the ADP (Skunk Works), perhaps to avoid these recurring TDN "doubleups".

So we can see the Skunk Works sometimes using conflicting TDNs, but they are not necessarily evidence of a separate scheme, or the main Lockheed California department wouldn't have cared about the CL-1200 "double up".

 

[Arjen]

In Lockheed's Skunk Works, 1995 revised edition, page 157, Miller quotes a 'notation' of Johnson to his team members:

It is advisable to change the design number of our Light Weight Fighter from the CL-1200 to another serial. The reason for this is to impress the Air force with the fact this is truly a new aircraft and responsive reaction to their request for bid on the subject aircraft. We have been advised to play down the fact that our Lightweight Fighter is derived from the CL-1200, the X-27, or the F-104. In response to this suggestion, I have obtained the design number CL-1600 for our proposed aircraft. Rationale for this number has to do with our desire to avoid the 1300 and 1500 series for obvious reasons, the latter of course being conflict with the F-15.

The text on CL-900 through -1600 numbers from the 1988 edition of The X-Planes is repeated in the 2001 revised edition.

 

[hesham]

OK my dears,may it was not a series.but as my dear PaulMM said,they duplicated
some designs,such as CL-1600.