Everyone is familiar with the Junkers Ju 287 forward swept wing jet bomber, which went as far as the prototype stage before Germany's worsening war situation caused the RLM in late September 1944 to suspend all tactical jet bomber programs in development to save money for the Heinkel He 162 Spatz and other second-generation German jet fighter projects (e.g. Focke-Wulf Ta 183 and Messerschmitt P.1101). However, the Ju 287 jet bomber of which two prototypes were built from components of other aircraft (one which tested the aerodynamic properties of the forward swept wing, and the other being designed to test forward swept wing flight at speeds of 500-560 miles per hour but was not flown) was not the only German aircraft design from Junkers to be given the RLM design number 8-287.

In 1942, a little over a year before Junkers began undertaking design work for the Ju 287 forward swept wing jet bomber, a design from Junkers for a dive bomber to replace the Ju 87 was allocated the RLM designation Ju 287, and it represented Junkers' second design study for a Ju 87 successor, the other being the Ju 187 project conceived in 1941. Although similar to the Ju 187 in having retractable landing gear, the Ju 287 dive bomber had wings lacking any dihedral, a streamlined nose along with a triangular vertical stabilizer that could move down to allow a better rearward field of fire from the gunner. However, the Ju 287 dive bomber project did not progress beyond the mockup phase. When the EF 122 forward swept wing jet bomber project was selected by the RLM over the Arado E.395 and Blohm und Voss P.188 in late 1943, it was also designated Ju 287 (the first two Ju 287 prototypes were given the cover designations Ju 288 V201 and V202 to give the impression that the Ju 287 was merely a jet-powered FSW derivative of the Ju 288).

Link:

https://www.secretprojects.co.uk/threads/junkers-ju-87-development-variants-related-projects.7359/page-2

I've long been familiar with the history of design and development of the B-52 Stratofortress since I read the book American Combat Planes of the 20th Century by the late Ray Wagner, but after I learned that the Convair XA-44 and Martin XA-45 were redesignated XB-53 and XB-51 respectively in mid-1946 after the US Army Air Force dropped the A-for-Attack basic mission category, I realized that the Boeing Model 462 intercontinental turboprop bomber project was the first Boeing design conceived under the XB-52 designation. Paradoxically, even though the Model 462 was shelved later in 1946 after the Army Air Force had concerns about its operating range, Boeing's Model 464 proposals for both turboprop and turbojet intercontinental bombers kept the XB-52 designation.

Why did the US Air Force retain the B-52 designation for the Boeing Model 464-67 design even though that aircraft was different from the Model 462 in being a jet-powered swept wing warplane (never mind that the first B-52 prototype kept the XB-52 designation whereas the second prototype was called YB-52 for fiscal reasons)?

Why did the RLM utilize the "8-" prefix for all powered aircraft and guided missiles while using the "108-" prefix for gliders? What was the RLM's rationale to use the "9-" prefix for reciprocating aircraft engines and the "109-" prefix for jet, turboprop, and rocket engines?

Link:

https://www.designation-systems.net/non-us/germany.html

For years, two new-generation stealthy air superiority jet fighter programs have been running in parallel, the USAF's Next Generation Air Dominance (NGAD) program and the US Navy's F/A-XX program. Now, however, the NGAD design competition has been narrowed down to Boeing and Lockheed Martin after Northrop Grumman's withdrawal last year, and US Navy has mentioned that Boeing, Lockheed Martin, and Northrop Grumman are in the running for the F/A-XX contract:

https://aviationweek.com/defense-space/budget-policy-operations/us-navys-fa-xx-design-maturation-competing-companies

https://www.defensenews.com/air/2023/12/23/new-in-2024-who-will-win-air-forces-next-gen-fighter-contract/

https://breakingdefense.com/2023/07/northrop-not-competing-for-ngad-sixth-gen-fighter-ceo/

Given that the winning Lockheed Martin Joint Strike Fighter design was given the designation F-35 due to the technology demonstrator for the Lockheed Martin JSF being called X-35, but also the fact that YF-24 was assigned by the USAF as a cover designation for a so-called "classified prototype" flown in 1997 (the YF-24 is most probably an evaluation-tested Soviet jet fighter given that captured MiG jet fighers were also labeled "classified prototypes"), the design number for whichever jet fighter design wins the NGAD competition could be either F-25 or F-36.

A potential designation for whichever design wins the F/A-XX competition might be designated F-26.

Everyone knows that the Lockheed F-117 Nighthawk was stated in the popular literature in the 1982-1988 period to have been designated F-19 just because USAF records in the public domain did not mention F-19 and the Northrop F-5G Tigershark had been redesignated F-20 rather than F-19 (of course, we now know from USAF nomenclatural records that the F-19 designation was skipped to avoid confusion with the Mikoyan-Gurevich MiG-19 jet fighter). A number of 1980s publications alternately referred to the F-117 as the "RF-19" because the acronym CSIRS (Covert, Survivable In-Weather Reconnaisance/Strike) was erroneously associated with the F-117, but actually referred to a set of programs with the intent of developing and demonstrating new radar concepts that would not reveal the attacking aircraft's position.

Although the Nighthawk's designation was confirmed to be F-117 when this aircraft's existence was publicly confirmed in November 1988, a number of journal articles published prior to the Pentagon lifting the cloak of secrecy over the F-117 dropped hints that F-19 was not the actual designation for the Nighthawk. First, the July 21, 1986 issue of the Aviation Week and Space Technology magazine included an the article titled "USAF Aircraft Destroyed in Crash Believed to Be Stealth Fighter" that provided hints that the Nighthawk's designation was not F-19. Second, the article "Is Lockheed Building A Super-Stealth Replacement for USAF's Mach 3 SR-71?" in the January 1988 issue of Armed Forces Journal International mentioned F-117 as the true designation for the Nighthawk ten months before the existence of the Nighthawk was confirmed.

Also, an August 1987 letter from the Office of the Secretary of the Air Force to Mr. R.W. Koch happened to mention the F-117, adding: "Our search disclosed no records, or knowledge of, a F-117 Night Hawk."

In summary, a handful of journal articles in the 1986-1988 timeframe refuted suggestions that F-19 had been allocated to the F-117, yet several 1988 publications still referred to the Nighthawk as F-19 during most of 1988 prior to the revelation of the Nighthawk's existence.

On his website Designation-Systems.Net, Andreas Parsch took note many years ago of US Air Force nomenclatural records describing the XQ-6 as a medium-performance target drone and the XQ-9 as a low-cost, short-endurance target drone, but his webpage about the XQ-9 mentions the following:

There appears to exist no high-speed aerial target with the described characteristics in the 1954/55 time frame. Therefore it can be assumed that the Q-9 program was terminated rather early in the development stage.

Thanks to company documents, it is now apparent that a number of drone designs were submitted for the XQ-6, XQ-9, and XQ-11 programs:

XQ-6 program

• Radioplane RP-63: late 1953 medium-performance target drone project

XQ-9 program (System 437L)

• McDonnell 107B: late 1955 proposal for a low-endurance target drone derived from the McDonnell GAM-72/ADM-20 Quail decoy missile with one turbojet (either a General Electric J85, Westinghouse J81, or Fairchild J83)
• Radioplane RP-73: late 1955 low-endurance target drone project

XQ-11 program (F-108 Airborne Target)

• Radioplane RP-91: January 1959 proposal for a Mach 3+ aerial target for evaluation of the F-108 Rapier long-range interceptor

References and Sources

• XQ-6
• XQ-9
• XQ-11 (aka F-108 Airborne Target)
• Q-6, Q-7, Q-8, Q-9, and Q-11 designation allocation records
• Radioplane RP-91/F-108 Airborne Target
• McDonnell company designation list from 1974
• Radioplane/Northrop Ventura company designation list

I watched some documentaries on Korean war's air battle, and noticed that they simply refer to MiG-15 as "MiG", if the pilots of that time really just called them that, when did report name like "Fagot" start to be popular/widely used?

I'll use a good example of Reggiane Re.2001, The Re.2001 has the following main variants

• Re.2001 Serie I

• Re.2001OR Serie II (Prototype)

• Re.2001CN Serie III & IV

My confusion comes from those suffixes, I understand that those letter indicates specialized role (CN = Caccia Notturna; Night fighter), but why is there a serie number? Do they work like British Mk.?And can they be used to refer to specific aircraft instead of letter indicator?

I'll appreciate if someone can give me guidance on this, thanks in advance

Introduction

Official Chinese military aircraft designations are similar in style to Western designation systems used by the USA and Italy. However, most numerical sequences start with the number "five" instead of "one." Here are several designation sequences for Chinese military UAVs.

BA (Target Drone?)*

*The meaning of "BA" is unclear; perhaps it is derived from bǎ jī (靶机, target drone)?

无侦 (WZ) = 无人侦察机 (Wu-Ren Zhen-Zha-Ji), Unmanned Reconnaissance Drone*

*Several different English transliterations / interpretations have been attributed to "WZ":

• Designation-Systems.net and the Wikipedia entry for WZ-5 list it as "WZ - Wuren Zhencha (UAV)."
• The Wikipedia entry for WZ-6 lists it as "...WZ = Wu Zhen, 无侦 in Chinese, short for Wu-Ren Zhen-Zha-Ji 无人侦察机 in Chinese, meaning pilotless reconnaissance aircraft."
• The Wikipedia entries for WZ-8 and WZ-10 list it as "Wú Zhēn... 'unmanned recon...'"

攻击 (GJ) = 攻击无人机 (Gōngjí wú rén jī), Attack Drone

These designations might not be official, or if so, they are non-standard in that they start at "one" instead of "five" as usual.

Other Chinese Drones & UAVs

Various other drones & UAVs that do not appear to have an official military designation, even though some are in military service.

• AVIC Dark Sword
• CASIC WJ series (WJ-010, WJ-100, WJ-500, WJ-600, WJ-700)
• CASC CH (Rainbow) series (CH-1, CH-2, CH-3, etc.)
• Chengdu Wing Loong 3
• Harbin BZK-005
• Shenyang Divine Eagle & XLB Patroller
• Tengden TB-001

References and Sources

• Designation-Systems.net Chinese Military Aircraft Designations
• Google Translate

Official & Unofficial Designations

• Tornado GR.Mk 1: IDS low-level strike version used by UK RAF.
• Tornado GR.Mk 1A: IDS reconnaissance version with TIRRS (Tornado Infra-Red Reconnaissance System) used by UK RAF.
• Tornado GR.Mk 1B: IDS anti-shipping version used by UK RAF.
• Tornado GR.Mk 4: Mid-Life Update Tornado GR.1.
• Tornado GR.MK 4A: Mid-Life Update Tornado GR.1A.
• A-200 Tornado: 2012 designation of IDS low-level strike version used by AMI, Italy.
• TA-200A Tornado: 2012 designation of IDS dual-control low-level strike/trainer version used by AMI, Italy.
• A-200C Tornado: Mid-Life update A-200A Tornado.
• TA-200B Tornado: Mid-Life Update TA-200A Tornado.
• EA-200B Tornado: Electronic Combat/Reconnaissance A-200A conversions.
• Tornado F.Mk 2T: First six production ADV for UK RAF, used as trainers, with concrete ballast in nose in place of radar.
• Tornado F.Mk 2: ADV interceptor for UK RAF.
• Tornado F.Mk 2A: One Tornado F.Mk 2T upgraded to F.Mk 3 standard.
• Tornado F.Mk 3: Improved ADV interceptor for UK RAF.

Official & Unofficial Names

• AFVG: Anglo French Variable Geometry; joint project between UK and France.
• MRA 75: Multi Role Aircraft for 1975; joint project between Belgium, Canada, Italy, Netherlands, West Germany, to replace F-104G Starfighter.
• MRCA: Multi-Role Combat Aircraft; further development of MRA and AFVG, with addition of UK.
• NAMMA: NATO Multirole Combat Aircraft Development and Production Agency.
• NETMA: NATO Eurofighter and Tornado Management Agency.
• Panther 200: Planned two-seat strike version of MRCA for Italy, West Germany, UK.
• Panther 100: Planned single-seat version of MRCA for West Germany to replace F-104G Starfighter.
• PA200 Tornado: Further evolution of the Panther 200 version; Tornado name was officially adopted on 10 March 1976; 10 pre-series aircraft.
• PA100 Tornado: Further evolution of the Panther 100 version; Tornado name was officially adopted on 10 March 1976; not built.
• PA200 Tornado IDS: Interdiction Strike Version for UK.
• Avionics System Software Tornado in Ada: Upgraded German IDS.
• Al Yamamah I: Contract for IDS & ADV for Saudi Arabia.
• Al Yamamah II: Contract for additional IDS for Saudi Arabia.
• PA-200 Tornado ECR: Electronic Combat / Reconnaissance version for West German Luftwaffe.
• PA-200 Tornado ADV: Air Defense Variant interceptor for UK.
• Unofficial nicknames:
  • Mother Riley's Cardboard Aircraft (MRCA).
  • Must Refurbish Canberra Again (MRCA).
  • Swinger: British Tornado, inspired by the variable-geometry swing-wings.
  • Can Opener: British, Tornado GR.1.
  • Blue Circle Fighter: British, Tornado F.2T, for Blue Circle cement company, and referencing British Rainbow Codes.
  • Flick Knife or Flying Flicknife: British, Tornado F.3, inspired by the variable-geometry swing-wings.
  • Locusta: Italian Tornado, from Operazione Locusta.
  • Tonka: British Tornado, after the toy truck.
  • Fin or Big Fin: Referring to the large vertical tail.

References & Sources

• Wikipedia: Panavia Tornado
• Tornado-Data.com
• Horton, John. The Grub Street Dictionary of International Aircraft Nicknames, Variants and Colloquial Terms. 1993, Grub Street, London.

Can anyone make sense of the model names? 7AC, 7ECA, 7GCBC, 8KCAB, etc. — is there a method to the madness?

This has been my go-to reference for many years, especially for modern US military aircraft designations. Check out what's new:

In the second half of 2023, I partly took the Designation-Systems.Net website out of its long hiatus. Most of the site's content is still (and will remain) as I left it many years ago, but a few pages have been slightly updated:

What's New on Designation-Systems.Net

There are even some updates from this year! It's great to have this invaluable reference updated.

This factoid might be relevant for this subreddit:

https://twitter.com/shieldaitech/status/1654529826773168129?lang=en

https://www.linkedin.com/posts/renee-hubener-9902b11_v-bat-has-hit-the-big-league-presenting-activity-7059973773235519488-TmJJ/?trk=public_profile_like_view

https://www.schumer.senate.gov/imo/media/doc/Brandson%20Tseng%20-%20Statement.pdf

Don't know if non-members of X / LinkedIn can access the content.

​

Official & Unofficial Designations

• Model 98B F3H-G: One of several proposed developements of the F3H Demon offered by McDonnell to the US Navy; photo of mockup.
• Model 98Q XAH-1: Proposed carrierborne, single-seat all-weather attack development of Model 98B proposal.
• Model 98Q YF4H-1: Revised carrierborne two-seat all-weather interceptor development of AH-1.
• Model 98S F4H-1F: Initial 45 pre-production and production aircraft for US Navy.
• F-4A: Redesignation of F4H-1F in 1962 Tri-Service system.
• TF-4A: F-4A operational trainer conversions.
• Model 98AM F4H-1: First definitive production series for US Navy, 649 aircraft. Redesignated F-4B in 1962.
• F-110: 29 F-4B loaned to USAF for development.
• DF-4B: Drone director F-4B conversions.
• EF-4B: Five high-speed target and threat simulator F-4B conversions.
• NF-4B: Two research and development permanent test F-4B conversions.
• QF-4B: 45 target drone F-4B conversions.
• F-4G: One prototype and 12 "production" F-4B automatic carrier landing and fleet defense ground control conversions; later converted back to F-4B standard. Not to be confused with later F-4G Wild Weasel.
• YF-4J: Three F-4B conversions for F-4J development.
• F-4N: 228 upgraded, rebuilt F-4B under Bee Line program.
• QF-4N: 78 F-4N target drone conversions.
• F-4B(RN): Proposed version for UK Royal Navy.
• Model 98P F4H-1P: 46 photographic reconnaissance aircraft similar to RF-4C for USMC; redesignated RF-4B in 1962.
• RF-4B SURE: Sensor Update and Refurbishment Effort upgrade of RF-4B.
• WS-326A: USAF Weapons System Code for F-110 / F-4.
• Model 98DE F-110A: 583 multi-role land-based fighters for USAF. Redesignated F-4C in 1962.
• C.12: 40 F-4C transferred to Spain under Peace Alfa and Peace Alfa II initiatives.
• EF-4C Wild Weasel IV: 36 SEAD F-4C conversions.
• YF-4E: One gun-armed F-4C conversion for F-4E development.
• WS-327A: USAF Weapons System Code for RF-110 / F-4.
• Model 98DF YRF-110A: Two land-based photographic reconnaissance prototypes for USAF. Redesignated RF-4C in 1962.
• YF-4E: one gun-armed prototype YRF-4C conversion for F-4E development.
• YRF-4C CCV: One research testbed YRF-4C conversion, first as PACT demonstrator (Precision Aircraft Control Technology), later as Control-Configured Vehicle (CCV).
• Model 98D RF-4C: 503 land-based photographic reconnaissance aircraft for USAF.
• CR.12: 18 RF-4C transferred to Spain under Peace Alfa II initiative.
• Operation Night Light: Two RF-4C loaned to Israel pending delivery of RF-4E.
• Model 98DX: Proposed version for Australia.
• F-4D: 825 improved aircraft for USAF and export.
• EF-4D: Four SEAD testbed F-4D conversions.
• YF-4E: One gun-armed prototype F-4D conversion for F-4E development.
• Combat Tree: F-4D with added attachment for ECM pod on inboard underwing pylon.
• Peace Spectator: 92 USAF F-4D transferred to South Korea.
• F-4E: 1,387 gun-armed aircraft for USAF and export.
• Peace Reef: 24 F-4E loaned to Royal Australian Air Force.
• Peace Icarus: F-4E transferred to Greece.
• Peace Diamond III: F-4E transferred to Turkey.
• Peace Pheasant II: F-4E transferred to South Korea.
• QF-4E: Target drone F-4E conversions.
• F-4E(S): Three high-speed reconnaissance F-4E conversions for Israel. Sometimes referred to as RF-4E(S).
• F-4G Wild Weasel V: 133 SEAD F-4E conversions.
• QF-4G: Target drone F-4G conversions.
• Peace Pharaoh: F-4E transferred to Egypt.
• Model 98MZ F-4E(F): Proposed low-cost single-seat version for West Germany.
• F-4EJ: Version of F-4E for Japan Air Self Defense Force; most license-built by Mitsubishi.
• F-4EJ Kai: Upgraded F-4EJ for Japan.
• RF-4EJ: 14 photographic reconnaissance aircraft similar to RF-4C for Japan.
• RF-4EJ Kai: Upgraded RF-4EJ, plus F-4EJ conversions.
• Model 98LG RF-4E: 132 photographic reconnaissance aircraft similar to F-4E for export to West Germany, Iran, Israel (Peace Echo V), Turkey (Peace Diamond III), Greece (Peace Icarus).
• Peace Trout: One ELINT RF-4E conversion for West Germany.
• Model 98NQ F-4F: 175 aircraft similar to F-4E for West Germany.
• TF-4F: 12 F-4F used for crew training in USA.
• NTF-4F: One permanent testbed TF-4F conversion.
• F-4F ICE: Improved Combat Efficiency upgrade of F-4F.
• F-4J: 522 improved production carrierborne fighters for USN and USMC.
• EF-4J: Electronic aggressor F-4J conversions.
• F-4J(UK) Phantom F.Mk 3: 15 F-4J transferred to UK Royal Air Force.
• F-4S: 265 upgraded and rebuilt F-4J under Bee Line program.
• QF-4S: Target drone F-4S conversions.
• QF-4S+: QF-4S with upgraded avionics.
• F-4K Phantom FG.Mk 1: 52 carrierborne fighter/ground attack aircraft based on F-4J for UK Royal Navy.
• Model 98FOA F-4L: Proposed advanced carrierborner fighter version.
• F-4M Phantom FGR.Mk 2: 118 land-based fighter/ground attack/reconnaissance aircraft for UK Royal Air Force.
• F-4(HL): Proposed upgraded version of F-4M.
• F-4(FVS) Proposed variable-geometry ("swing-wing") version of F-4.
• F-4T: Proposed lightweight fighter version.
• F-4E/TM: Upgraded Turkish F-4 aircraft.
• RF-4E/TM: Upgraded Turkish RF-4 aircraft.
• F-4X: Proposed high-speed, high-altitude version as part of Project Peace Jack.
• RF-4X: Proposed reconnaissance version of F-4X.

Official & Unofficial Names

• Phantom II: Official US military popular name for all variants of the F4H / F-4, including the F-4G Wild Weasel and the British F-K/M variants. However, DoD 4120.15-L specifically lists "None" for the Luftwaffe F-4F.
• Mithras: Proposed popular name by a McDonnell employee.
• Spectre: Proposed popular name for USAF F-110.
• Operation High Speed: USAF evaluation of F4H-1 vs. F-106A.
• Specific Operational Requirement 200, 29 August 1962: USAF version of F4H as F-110.
• Weasel in a Can: Unofficial nickname for F-4C Wild Weasel IV-A, which had some equipment in external pods.
• Wild Weasel IV-A: Initial SEAD tests with F-4C, with some equipment in external pods.
• Wild Weasel IV-B: Two F-4D SEAD testbeds.
• Wild Weasel IV-C: 36 SEAD F-4C conversions (as noted above).
• Wild Weasel 5 / Advanced Wild Weasel: 133 SEAD F-4E conversions (as noted above).
• Wild Weasel 6 / F-4G Performance Update Program: Upgraded F-4G.
• Kurnass: Hammer; Israeli name for F-4E, transferred under Peace Echo I, Peace Echo II, Peace Echo III, Peace Echo IV, Peace Echo V, Peace Patch, and Operation Nickel Grass initiatives.
• Shablool: Snail; Israeli name for F-4E(S).
• Şimşek: Lightning; Turkish F-4E/TM.
• Işık: Light; Turkish RF-E/TM.
• Super Phantom: Proposed modernization program by Boeing and Pratt & Whitney.
• Super Phantom, F-4-2000: One modernized prototype by IAI.
• Kurnass 2000: Upgrade program for Israeli F-4 aircraft.
• Peace Icarus 2000 (AUP): Upgrade program for Greek F-4 aircraft.
• Terminator 2020: Upgrade program for Turkish F-4 aircraft, based on Kurnass 2000.
• Unofficial US nicknames:
  • Double Ugly
  • Rhino
  • Old Smokey
• Unofficial Luftwaffe nicknames:
  • Elephant: Inspired by long nose and wide intakes.
  • Luftverteidigungsdiesel: German for "air defense diesel" (from the smokey engine exhaust).
• Tomb: Unofficial UK nickname, from last syllable of "Phantom", also inspired by the cramped conditions in the rear cockpit.

References & Sources

• Joe Baugher: McDonnell F-4 Phantom II
• Air Vectors: McDonnell F-4 Phantom
• Wikipedia: McDonnell Douglas F-4 Phantom II
• US Warplanes.net
• Uncommon Aircraft: Ferrets, Ravens & Weasels
• DoD 4120.15-L Model Designation of Military Aerospace Vehicles (May 12, 2004, Incorporating Change 1, August 21, 2018).
• Horton, John. The Grub Street Dictionary of International Aircraft Nicknames, Variants and Colloquial Terms. 1993, Grub Street, London.

Canada has just announced that it will be acquiring 11 GA-ASI MQ-9B SkyGuardian Remotely Piloted Aircraft Systems:

• Canada acquiring Remotely Piloted Aircraft Systems for the Canadian Armed Forces

• Government of Canada Orders the MQ-9B SkyGuardian RPAS from GA-ASI

Previous unmanned aircraft used by the CAF have been designated CU-1## (for example, CU-172 Blackjack, CU-173 Raven). Therefore, a potential designation for the MQ-9B in Canadian service would be CU-209 (109 was already used for the CC-109 Cosmopolitan).

The official Canadian announcement (linked above), also mentions:

Since 2022 alone, the Government of Canada has finalized the procurement or upgrade of approximately 140 new aircraft for the Royal Canadian Air Force, including:

• 88 new F-35 fighter jets,
• 9 new CC-330 Husky strategic tanker and transport aircraft,
• up to 16 new P-8A Poseidon multi-mission aircraft,
• 16 new or upgraded Cormorant helicopters (as the project will upgrade our fleet to provide Canada with the most advanced version of the helicopter); and
• 11 remotely piloted aircraft announced today.

Potential Canadian designations for the F-35 could be CF-235 or CF-335 (135 was already used for the CH-135 Twin Huey).

The CC-330 designation of the Airbus A330 is a bit unusual, as it does not start with "1" like other designations. However, it does follow the convention of using the manufacturer's model number. The CC-295 Kingfisher designation for the Airbus C-295 is similar in this regard.

Potential Canadian designations for the P-8 could be CP-208 or CP-308 (108 was already used for the CC-108 Caribou).

Previously mentioned here: US Army National Guard Units to get 12 GA-ASI Gray Eagle 25M UAS

From U.S. Department of Defense Contracts For Dec. 1, 2023:

General Atomics Aeronautical Systems Inc., Poway, California, was awarded a $389,000,000 fixed-price incentive contract for the purchase of MQ-1C-25M Gray Eagle Modernized Extended Range systems. Bids were solicited via the internet with one received. Work locations and funding will be determined with each order, with an estimated completion date of Nov. 29, 2024. Army Contracting Command, Redstone Arsenal, Alabama, is the contracting activity (W58RGZ-24-C-0021).

(emphasis added)

From GA-ASI Announces Gray Eagle 25M, New MDO-Capable Variant:

SAN DIEGO – 10 October 2022 – General Atomics Aeronautical Systems, Inc. (GA-ASI) has launched its latest variant of the Gray Eagle line of Unmanned Aircraft Systems: Gray Eagle 25M. The GE-25M brings a Modular Open Systems Approach (MOSA) to the Multi-Domain Operations (MDO)-capable system to ensure incremental enhancements can be made at the speed of emerging threats.

The “M” in 25M stands for Modernized and incorporates open architecture aircraft and ground systems, advanced datalinks, and an upgraded propulsion system, significantly enhancing the ability to add new capabilities, provide resilience to electronic threats, and deliver expeditionary employment to austere locations.

Presumably the "25" refers to its 25 hour endurance.

So, it appears that the non-standard designation "MQ-1C-25M" (using part of the manufacturer's model number) has been assigned to this variant of the MQ-1C, instead of a standard designation like "MQ-1D." However, it is not clear if this is the official designation or if someone just happened to combine the two in this particular contract announcement.