Early aircraft prototype serial numbers

[DogTailRed2]

Why were prototype serial numbers prefixed with K regardless of manufacturer for example Supermarine Spitfire K5054, Fairey Battle K4303 where as
service serials were not?

[oxenos]

Initially, aircraft were given serial numbers only. By 1916 they had run out of 4 digit numbers, and started using a letter plus up to 4 numbers. By 1929 they got to the K series. By 1940, with increased aircraft production, they got to Z9999, and started on two letters plus 3 numbers. Not sure where you got the idea that service serials other than prototypes did not have a letter. That was only the case pre - 1916.

[treadigraph]

The first production batch of Spitfires was K9787 - L1096...

I recall seeing pics of Miles prototypes wearing U- plus four digits - eg Miles M.20 was U-0228. Anyone else do it and was it an Air Ministry concept?

[oxenos]

U was not used as an Air Ministry serial, so must have been some other system.

[DaveReidUK]

U was not used as an Air Ministry serial, so must have been some other system.

There was a system of non-military registrations used by manufacturers. Miles was allocated "U".

[DaveReidUK]

Why were prototype serial numbers prefixed with K regardless of manufacturer for example Supermarine Spitfire K5054, Fairey Battle K4303 where as
service serials were not?

Purely date-related:

https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/354x500/the_k_file_f3c7ac778520ee8bd8922db53269969786f178dc.jpg

[Jhieminga]

The first production batch of Spitfires was K9787 - L1096...

I recall seeing pics of Miles prototypes wearing U- plus four digits - eg Miles M.20 was U-0228. Anyone else do it and was it an Air Ministry concept?
It's explained here: https://en.wikipedia.org/wiki/United_Kingdom_aircraft_test_serials
Early in WWII they were modified to look like military serials, but it was the precursor to the later G-21- (for Miles) test registrations.

[treadigraph]

Cheers guys! Occasionally wondered about the U- markings.

Can't think I've actually ever seen anything in the flesh carrying B class markings, though my visits to production airfields have been pretty limited.

[G-ARZG]

At the risk of kicking over the rock marked 'woeful state of our industry etc etc' I doubt there are many places you would see a Class B reg these days.

Certainly evident during (long) past visits to Warton (G27-) and Hatfield (G5-)

[treadigraph]

My visits were Bembridge, Hatfield and Dunsfold in the 70s/80s, don't think I went anywhere else.

[Quemerford]

Not "Class B reg" or similar. As I recall (from being chastised for stating something else), the term was/is always "Under B Conditions". Last aircraft I recall carrying a B Conditions serial number was a Strikemaster at Hurn, circa 1981.

[Jhieminga]

There is a 1978 publication titled 'Under B Conditions' that lists a lot of the relevant registrations and users. There also appears to be a 2020 updated version from the same author but the single review on Amazon states that it has more errors than the 1978 version.... See here: https://amzn.to/49anWI3

[bobward]

Going back to the original question. Weren't there 'black out blocks' where batches of serial numbers were jumped, to confuse the opposition as to how many aircraft had been ordered?
I think this was done mainly before WW2, although it carried on into the Cold War. Serial blocks also seem to be flexible these days too. Have a look at Crecy's "Military Aircraft Markings " (Spotters Bible!") to see what I mean.

[Jhieminga]

That's a good question... one I don't know the answer to. There were of course several blocks (large and small) where serials were originally allocated but the airframes were not ordered. You would have to trawl through the lists to find these, off the top of my head I can only list XV110 to XV114 that were never taken up for their intended use. So the question remains whether they every intentionally skipped any blocks of serials.

[sycamore]

Try` UKSERIALS.COM`....

[DaveReidUK]

Going back to the original question. Weren't there 'black out blocks' where batches of serial numbers were jumped, to confuse the opposition as to how many aircraft had been ordered?
I think this was done mainly before WW2, although it carried on into the Cold War. Serial blocks also seem to be flexible these days too. Have a look at Crecy's "Military Aircraft Markings " (Spotters Bible!") to see what I mean.

The first ever sequential serials to be left unallocated were L7273-L7276. They preceded a batch of 200 Manchesters/Lancasters, which will give an idea of the timeframe.

[DaveReidUK]

Try` UKSERIALS.COM`....

or, for the full story (at least as far as 1987):

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/537x750/bmas2_f202fde3d70f1ba2faf94ac5a674042ab303935c.jpg

[treadigraph]

1878? I knew that Ansons were in service for a long time but...

It was to be another fifteen years before the first official experiments with balloons were conducted in 1878 by the Balloon Equipment Store at the Woolwich Arsenal. Captain James L.B. Templer an officer in the Middlesex Militia and a keen amateur balloonist designed its first balloon. ‘Pioneer’,with its capacity of 10,000 cubic feet of hydrogen was constructed for just £71, and is considered to represent the birth of the British air arm.

One lives and learns, I had thought Nulli Secundus was the start of it all... :)

https://www.rafmuseum.org.uk/research/online-exhibitions/rfc_centenary/british-military-aviation-1862-1912/early-military-ballooning/

[Planemike]

That's a good question... one I don't know the answer to. ff the top of my head I can only list XV110 to XV114 that were never taken up for their intended use. So the question remains whether they ever intentionally skipped any blocks of serials.
A/B Aeromiltaria Winter 2014 notes that XF804 - XF823 were allocated but never used. Apparently the intention was to use them on aircraft operated by the Kenya Police Air Wing (KPAW). Around that time the Air Wing operated Piper PA-22 Tripacer 135s and a de Havilland Chipmunk. Slightly later the Air Wing purchased and operated several Cessna 180s. All the aircraft continued to be civilian registered (VP-K**).

[ETOPS]

Used to see the Avro (later Hawker Siddeley) 748 test flights from Woodford wearing G-11-** marks before registration and delivery. As an aside their construction numbers were always referred to as “set numbers”

[possel]

My visits were Bembridge, Hatfield and Dunsfold in the 70s/80s, don't think I went anywhere else.
At Bembridge you should have often seen G-51-xxx Islanders. Hatfield used to have (in the 70s) 125s from Hawarden with G-5-xxx (when I was there!).

[possel]

Going back to the original question. Weren't there 'black out blocks' where batches of serial numbers were jumped, to confuse the opposition as to how many aircraft had been ordered?
I think this was done mainly before WW2, although it carried on into the Cold War. Serial blocks also seem to be flexible these days too. Have a look at Crecy's "Military Aircraft Markings " (Spotters Bible!") to see what I mean.
It carried on into the late 1980s. The Contracts Branch in MOD(PE) were the people who issued serial numbers. The Kuwait Tucanos (16 aircraft) were serialled in two blocks of 8 for this reason. Then, when a Kenyan Tucano crashed before delivery, they refused my request to add the replacement aircraft onto the end of the block of the 12 aircraft already serialled. However, I believe that they have now stopped the block practice (but I'm so out of touch) and they just jump about all over the place (e.g. the ZZ17x c-17s).

[treadigraph]

At Bembridge you should have often seen G-51-xxx Islanders. Hatfield used to have (in the 70s) 125s from Hawarden with G-5-xxx (when I was there!).
All the ones I saw at Bembridge a couple of times in the late '70s had full G-regs, didn't get around the assembly line! Hatfield was early '80s open days, 146 production was gearing up. Did foreign Hawks/Harriers ever wear them? Dunsfold examples all carried their service serials on the prod line (used to blag into Families Day - went more officially about thirty years ago), saw the odd Hawk do an ILS approach and go around at Gatwick but no idea if they were pre-delivery RAF or export aircraft.

[SWBKCB]

Used to see the Avro (later Hawker Siddeley) 748 test flights from Woodford wearing G-11-** marks before registration and delivery. As an aside their construction numbers were always referred to as “set numbers”

The set numbers for 748's were separate from the construction numbers - individual aircraft had both. I think the set number was related to their position on the production line.

[CAEBr]

Did foreign Hawks/Harriers ever wear them?

Many of the 50 Series export Hawks were flown under B conditions (as I believe were Hunters), however, any weapons trials on these saw them allocated a UK military serial. At this time G-HAWK (and G-VTOL) were operated by the company on trials and demonstration flights, but the CAA became increasingly unhappy with civil aircraft operating with ejection seats and ERUs, which led to the introduction of Def Stan 05-122 - COMA, Civil Owned Military Aircraft. Both these jets then transferred to the UK military register.
By that stage, control of Hawk had moved to Brough and we were allocated military registrations for all export aircraft (after the application and approval of the necessary paperwork). Within those we did manage some personalised registrations, eg ZJ951 (first Adour 951 engined aircraft).

[DaveReidUK]

The set numbers for 748's were separate from the construction numbers - individual aircraft had both. I think the set number was related to their position on the production line.

Though some Avro military types, the Vulcan B.2 for example, had no manufacturer's serial number, only a set number.

[Rhys S. Negative]

Did foreign Hawks/Harriers ever wear them?

Adding to CAEBr's answer, the last Hawk export batch to use G-9-nnn registrations were the Mk.64s for Kuwait, G-9-531 to '542, c.1986. As far as I know there was only one allocation higher than that: G-9-543 was worn by Hawk T.1 XX167 borrowed back from the RAF for some demonstration or training flights in 1984. The first Indian Sea Harrier FRS.51 used G-9-478 for its initial flying and appeared as such at the 1982 Farnborough show.

[treadigraph]

The first Indian Sea Harrier FRS.51 used G-9-478 for its initial flying and appeared as such at the 1982 Farnborough show.

Well, I must have seen it as such then as I most certainly attended! Cheers, :ok:

[ATSA1]

https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/1600x759/in_sea_harrier82_083e719da94c4128ed7544074582c34e0f3a470f.jp g
Indian Sea Harrier, Farnborough 1982

[ATSA1]

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1600x962/bae748_farnboro82_6e9c6b057c9d896bb4d0b64071d17bd623493a16.j pg
BAe 748, Farnborough 1982

[NavalAirHistory]

When letter prefixes were introduced, the 'N' block was reserved for naval aircraft, unsurprisingly. When N ran out, they moved to S for reasons that aren't entirely clear - Senior Service perhaps?

[DaveReidUK]

When letter prefixes were introduced, the 'N' block was reserved for naval aircraft, unsurprisingly. When N ran out, they moved to S for reasons that aren't entirely clear - Senior Service perhaps?

Hopefully there will be a Naval Air History expert along soon to explain why.

[Haraka]

FYI Vinten Prototype autogiro was G 55 1
This was 1985/6

[CAEBr]

When letter prefixes were introduced, the 'N' block was reserved for naval aircraft, unsurprisingly. When N ran out, they moved to S for reasons that aren't entirely clear - Senior Service perhaps?

The letter prefixes were introduced in 1916, with the Axxxx batch allocated to RFC aircraft, and Nxxxx allocated for RNAS aircraft. It continued to be used after the RAF was formed, for Coastal/Fleet types.
After 1926 they went to Sxxxx, S standing for Sea. The R series was already in use, so S was both fortuitous and the next available.

More details are available at
British Serial Numbers from 1912 to the Present by Steve Murray (http://www.clubhyper.com/reference/britishserialssm_1.htm)

[DaveReidUK]

The letter prefixes were introduced in 1916, with the Axxxx batch allocated to RFC aircraft, and Nxxxx allocated for RNAS aircraft. It continued to be used after the RAF was formed, for Coastal/Fleet types.
After 1926 they went to Sxxxx, S standing for Sea. The R series was already in use, so S was both fortuitous and the next available.

The S series was relatively short-lived and was abandoned in 1930 after less than 10% of the range had been used, with subsequent nautical aircraft being serialled in the regular (then) K series.

There was of course a second N series (following on from L) with no specific naval connections.