When searching the internet or reading aviation-related magazines and books it seems there is no uniform use of Gulfstream aircraft type- or sub-type designations. Gulfstream reports. did an investigation, based on various sources, to identify the correct Gulfstream aircraft designations.
Gulfstream Aerospace Corporation
Some years ago Gulfstream reports. had an e-mail conversation with an employee of Gulfstream Aerospace Corporation (GAC), Savannah (GA). From this conversation the following information emerged: The official Gulfstream marketing branding edict dictates that all Gulfstream aircraft will be known and displayed in marketing literature as 'G' following by the appropriate roman or numerical character. For example GI, GII, GIII, GIV, GV, G300, G450, G550. When enhancements to the base model are made, they shall appear as, for example GIV-SP or GV-SP. When visiting the official Gulfstream website (http://www.gulfstream.com) it also shows that, for example in the photo section, designations like GI, GII and GIII are used. However, the picture below shows the official designations from the Gulfstream type certificates. It gives type-designations displayed as for example G-159, G-I, G-1159A, G-IIB, G-IV and G-V.
Said that, the Supplemental Type Certificates (STC) variations show GIC, GIITT, GIIB and GIISP. So no uniform type-designations even inside GAC! Expected from the official Gulfstream marketing branding edict are sub-type designations like GI-C, GII-TT and GII-SP. The conclusion of the Gulfstream employee was that since the marketing department are primarily concerned with the core models, they do not have an opinion from a branding point of view on supplemental type certificates. So whatever the open market calls them seems appropriate.To complicate even more, the marketing department prefers employees of GAC to use the full 'Gulfstream IV', 'Gulfstream V' and so on in correspondence and discussions since these are the official trademarks. A 1968 "Design Summary" shows the use of the Gulfstream II designation in official Grumman Aircraft Engineering Corporation publications.
Some additional information about this could be found in the GAC Corporate Identity Guide: "Trademarks are meant to be used as adjectives, not nouns. Therefore, you should avoid using the word "Gulfstream" as a noun referring to an individual aircraft. "The GV" should only be used as an adjective for "the GV aircraft" Do not use the plural terminology "Gulfstreams" when refering to various Gulfstream aircraft". In summary:
Another 'official' source of information is the constructors plate of an aircraft. The constructors plate can be found on every Gulfstream aircraft. It identifies the airframe and gives information regarding type-designation and serialnumber (s/n). Looked at a GII constructors plate the 1159 model designation is used.
If a constructors plate of a modern Gulfstream aircraft, for example a Gulfstream G450, is studied more closely it gives the following type-designations: Gulfstream G450 and GIV-X (G450). This supports what's said earlier about the core models. Gulfstream aircraft will be known and displayed as 'G' following by the appropriate roman or numerical character. Enhancements to the base model shall appear as, for example GIV-SP, GV-SP or in this case GIV-X.
When reading aviation-related magazines and books it also supports the fact that there is no uniform use of Gulfstream aircraft type-designations. Listed below are some well-known aviation magazines and two leading books on Gulfstream history. Because these are no 'official' GAC sources they are just mentioned to illustrate the open discussion on Gulfstream aircraft designations. In summary:
So, what are the correct Gulfstream aircraft designations? From the studied information sources the following is clear: the current Gulfstream aircraft models are designated G450, G550, G650 or even better Gulfstream G450, Gulfstream G550 and Gulfstream G650. This is the same for the GIV and GV or Gulfstream IV and Gulfstream V. Enhancements to the base models GIV and GV are designated as GIV-SP and GV-SP. This is also supported by the Gulfstream G450 constructors plate which shows the GIV-X designation and not for example G-IVX or GIVX. The Gulfstream I, Gulfstream II and Gulfstream III designations, including enhancements to the base model, are open for discussion as was explained in this study. Everything seems appropriate. Following the GAC marketing branding edict and GAC website, Gulfstream report. will use the 'G' following by the appropriate roman character for the GI, GII and GIII or the Gulfstream I, Gulfstream II and Gulfstream III designations. Enhancements to the base model will be designated GI-C, GII-SP, GII-TT or Gulfstream I-C, Gulfstream II-SP and Gulfstream II-TT. Designations like G.159, G-159, G.1159 or G-1159 will not be used except when documenting Gulfstream history.