Curtiss aircraft: The original L- design/model system

[memaerobilia]

Another set of Curtiss designations to be sorted?
Just when it was all starting to make sense, a new puzzle (for me, a least)pops up, while working with the CW archival materials.
Came across a full carton of Original early Curtiss blueprints, that were found on the rows of storage shelves, and not in the file cabinets..
Half of the box is original Curtiss Company blueprints and technical Curtiss Engineering reports (BOTH types of documents done on blueprint form, with white text or dwg on blue paper.)
Most of these documents have "L" number designations and no mention of Curtiss design numbers that we have on this thread.
Example:
"F7C-1, (L-115-2) Navy Shipboard Fighter with P&W Wasp Engine" date: Nov5,1927. Seaplane
other "L" numbers on these documents are L-18-1, Pursuit ship. L-18-2 etc. L-18-3 is the PW8-A. L-71C-2 is a Curtiss Robin with the Challenger engine. L-18-23 is the P-6 Hawk. Most of these dwgs and reports are from early Curtiss Falcons and Hawks including Odd models such as the "CHILE Falcon" and N.A.T. Mailplane. So there is now the "L" series to chart. The dates on items in this box run fom 1922-1930 on the Curtiss originals. Blueprints up to 11 feet by 3 feet!

 

[Stargazer]

Another set of Curtiss designations to be sorted?
Just when it was all starting to make sense, a new puzzle (for me, a least)pops up, while working with the CW archival materials.
Came across a full carton of Original early Curtiss blueprints, that were found on the rows of storage shelves, and not in the file cabinets..
Half of the box is original Curtiss Company blueprints and technical Curtiss Engineering reports (BOTH types of documents done on blueprint form, with white text or dwg on blue paper.)
Most of these documents have "L" number designations and no mention of Curtiss design numbers that we have on this thread.

Omigod! You may just be about to solve one of Curtiss historians' greatest mysteries! The L- designations were engineering designations assigned by Curtiss before the 1935 system was adopted. Most of these L- designations have been lost, but if they could be traced and organized, they might shed some light on the exact chronology of when the various types were produced.

Here's the L- designations I have so far (no apparent logic there, but...):

L-17-1 Racer (Navy CR-1) > redesignated as Model 23
L-17-2 Navy Racer (Navy CR-2) > redesignated as Model 27
L-17-3 Hydro Racer (Navy CR-3) > redesignated as Model 23A
L-18-1 (Army XPW-8) > redesignated as Model 33
L-19-1 Cactus Kitten > redesignated as Model 22
L-22-1 Swift (Army XP-31) > redesignated as Model 66
L-72 Oriole (a.k.a. Experimental 519) > redesignated as Model 17
L79-1-1/5 Lark > redesignated as Model 41
L-117-1 Helldiver (Navy XF8C-2) > redesignated as Model 49
L-117-5 Helldiver (Navy XF8C-6) > redesignated as Model 49
L-411-1 Night Mail > overlooked in the 1935 system
L-710 Robin > redesignated as Model 50

 

[Stargazer]

Concerning the "odd" names you are refering to, they correspond to the following aircraft:

CHILE FALCON > also known as the D-12 FALCON, this was a South American export version redesignated as Model 37F in the 1935 system.

N.A.T. MAILPLANE > alternate name for either ten CARRIER PIGEON aircraft delivered to National Air Transport (N.A.T.) in 1926 (redesignated as Model 40 in 1935) or three CARRIER PIGEON II (CARRIER PIGEON CO) aircraft of a later variant delivered to N.A.T. in 1929.

I'd be VERY interested to read a listing of all the L- designations you've found. We could really advance in our understanding of how Curtiss designations worked before 1935! For instance, by comparing the data in your above post with my own I was able to determine that L-71 was the Robin in its various versions...

 

[memaerobilia]

I just had the "horrifying" realization, that it is now important to make a closer inspection of the many pre-1935, Curtiss Company aircraft photos, to see which ones may have "L" designations in those small handwritten white-ink descriptions in the lower left or right corners of the photos. I NOW recall seeing some. Oh my...

 

[Stargazer]

I just had the "horrifying" realization, that it is now important to make a closer inspection of the many pre-1935, Curtiss Company aircraft photos, to see which ones may have "L" designations in those small handwritten white-ink descriptions in the lower left or right corners of the photos. I NOW recall seeing some. Oh my...

;D ;D ;D

Wish I could help you out searching through these treasures... But there is a bit of a distance between us! Like 4000 miles or something...

 

[memaerobilia]

As I had hoped (or feared?), going back through the company photo archives will add a small additional amount of information on the "L" series designations. Will be busy with some other photo work to finish this weekend, but will get back to them, after the weekend. A quick look at Company photos already scanned in turned up this RARE Factory photo of the Curtiss PN-1, Army night pursuit fighter, with RARE 6 cyl. Liberty engine, design, only one built, (another was ordered, but cancelled) never flown (that I know of) and used for static tests in 1921. Clearly marked in lower right of photo as L-44-2. 1935 system has it as Design #21)

 

[memaerobilia]

Hi Stargazer;
"no apparent logic" indeed! the "L" numbers seem all out of order as to sequential numbers matching dates of productions.

Re: "L-411-1 Night Mail > overlooked in the 1935 system"
No this IS in the 1935 system, but the confusion may give you a headache.. ???
That system lists "Design #3; Night Mail; Canada; 1916; U.S. Mail; Buffalo."
But in the SAME data box on the chart, it ALSO lists "Design #3; Model T, Triplane boat; 1916; Buffalo. So, apparently a fast RE-designation of that number to or from one or the other?
Hopefully, NOT to be confused with design #16; HA Mailplane; 1919; 5 built;Navy; Liberty engine; Training biplane" The factory photos describe it as Exp 503, dated 6/11/19, at Garden City. and shows U.S. large Mailbag hanging from each side. (cannot tell if it is an actual large mailbag, or is a painted emblem of one?)

 

[Stargazer]

Hi Stargazer;
"no apparent logic" indeed! the "L" numbers seem all out of order as to sequential numbers matching dates of productions.

Re: "L-411-1 Night Mail > overlooked in the 1935 system"
No this IS in the 1935 system, but the confusion may give you a headache.. ???
That system lists "Design #3; Night Mail; Canada; 1916; U.S. Mail; Buffalo."
But in the SAME data box on the chart, it ALSO lists "Design #3; Model T, Triplane boat; 1916; Buffalo. So, apparently a fast RE-designation of that number to or from one or the other?
Hopefully, NOT to be confused with design #16; HA Mailplane; 1919; 5 built;Navy; Liberty engine; Training biplane" The factory photos describe it as Exp 503, dated 6/11/19, at Garden City. and shows U.S. large Mailbag hanging from each side. (cannot tell if it is an actual large mailbag, or is a painted emblem of one?)

After giving it some thought I've come to the conclusion that L-411-1 should actually read L-41-1-1 and the L-710 Robin should read L-71O (probably letter "O", and not the zero numeral). This is coherent with the Lark being L-79-1-1/5 and the Challenger Robin being L-71C. It seems that the first two-digit number indicated the model in chronological appearance, the first dash indicated the sub-version, and the second dash some possible variants of that sub-version. As to the letter after the two-digit number, it likely indicated the engine of that specific version. These are definitely NOT the 1935 system, which was introduced three years after Glenn Curtiss's death to make some sense of the remaining archives after a fire had destroyed part of them.

In sequential order, we now have:

L-17 (Navy and Army racers, with subtypes -1,-2 and -3)
L-18 (the whole Army Hawk series, with subtypes -1,-2,-3 and -23 identified so far)
L-19 (Cactus Kitten racer)
L-22-1 (Army P-31 Swift)
L-41 (Night Mail)
L-44 (PN-1 Night Pursuit)
L-71 (Robin, with variants L-71O and L-71C)
L-72 (Oriole)
L-79 (Lark)
L-115 (Navy F7C Seahawk, with subtype -2 identified and likely subtypes -1,-3 and -4 for the other variants)
L-117 (Navy F8C Helldiver, with subtypes -1 and -5 identified so far)

Chronology is still not completely respected here, but I think we are moving in the right direction.

However, to complicate matters some more, I have found the existence of a possible intermediary system with the mention of a "Model 19" for the F7C Seahawk (19A, 19B, 19D, 19E and 19G) and a "Model 26" (the Navy R3C-1 racer)!

I really think at this stage we would do greater advances if we both studied these complicated designations at the same time and then compared our conclusions. Do you have a way to quickly photograph the bottom corners of all your pics/blueprints or scan them when possible? This would ease matters considerably.

Curtiss history is by far my favorite subject when it comes to pre-war aviation and I would be so thrilled to make advances on the subject with your help!

 

[Stargazer]

Regarding the designation L-710, I have a number of engineering reports that carry this same number. I will have to review my work, but it seems to me that there are sub-designations for different Robins, such as L-710-1, L-710-2, L-710-3, etc. The dash numbers imply successively later Robin models which would correspond to Model B, Model C-1, Model C-2, Model J-1 ....... I have never fully broken the code between dash numbers and model numbers.

I don't think anyone has... yet!! ;D

Again, memaerobilia is your best bet for that sort of thing. I have tried a few times to convince him to work with me on systematic study of all the documents he has (I have a Curtiss website in the works) but he seems to be a busy man with plenty of other interests.

Anyway, L-710 was definitely the engineering designation of the Robin. I believe L-710-2 applied to the so-called Challenger Robin, or Model 50A. However, I haven't been able to find a suitable explanation for the high number in the 700 series. All other L- designations until then had been more or less sequential, with exceptions like the L-22. Here is what I have:

• L-17 for the Model 23 and 27 racers
• L-18 for the PW-8/P-1/P-6 fighter series
• L-19 for the Cactus Kitten racer
• L-22 for the Model 66 Swift (Army P-31)
• L-41 for the Night Mail
• L-44 for the Night Pursuit (later Model 21) (Army PN-1)
• L-79 for the Model 41 Lark
• L-115 for the Model 43 or Seahawk (Navy F7C)
• L-117 for the Model 49 or Helldiver (Navy F8C)

The only reason I can think of for the high, non-sequential number on the Robin is the fact that it was produced by a different subsidiary in a different plant.