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By: - 1st February 2008 at 17:54 Permalink - Edited 1st January 1970 at 01:00
http://www.aircraft.co.za/Encyclopedia/A/417.php
http://news.webshots.com/photo/2090810620067276411JQCHWu
http://en.wikipedia.org/wiki/Aeritalia_G.91
http://www.europa1939.com/aviones/apoyo/g91y.html
All from Google, where you'll find lots more...
By: - 2nd February 2008 at 05:49 Permalink - Edited 1st January 1970 at 01:00
A bit better drawing than that one on Wiki-waki (larger):
G91Y at Ramstein:
By: - 3rd February 2008 at 20:12 Permalink - Edited 1st January 1970 at 01:00
What was the engine layout of the "Y". Twin engine single intake?
By: - 3rd February 2008 at 21:46 Permalink - Edited 1st January 1970 at 01:00
G91/G91R/G91T: single nose intake, single Bristol-Siddeley Orpheus 803 turbojet; Max Power Rating 2,268kg (5,000lb) thrust.
G91Y: single nose intake, two (side-by-side) General Electric J85-GE-13A afterburning turbojets; Max Power Rating 1,236kg (2,725lb) dry thrust [1,850kg (4,080lb) with afterburning] each.
The G91/91R entered service in 1958, and the G91T in 1960. The G91Y first flew in December 1966.
The Orpheus used in the early G91s was the 803... an OR.3 series engine. In 1959, however, Bristol-Siddeley was testing an improved version, the Or.12, which was rated at 6,810 lb thrust. A version with a "take-off only afterburner", the Or.12R, was also tested, and rated at 6,810 lb (8,170 lb with afterburner).
In 1961, they produced the Or.500, rated at 5,750 lb thrust, which was installed in late-model C-119s as an auxiliary engine.
To me, either of these would have been good engines for an upgraded version that would have required far less redesign than the eventual twin-J85 did.
The Orpheus did have about the same fuel efficiency as the J85 (Or.3/803 SFC 1.080 lb fuel/lb thrust/hour; Or.12R .976/1.62; Or.500 .97; J85-13 1.03/2.22), but the redesign also increased the internal fuel capacity, resulting in increased range, as well as higher weapons load and better take-off/climb characteristics.
By: - 4th February 2008 at 07:42 Permalink - Edited 1st January 1970 at 01:00
Badger, were the sizes and weights of the upgraded Orpheus variants pretty much the same as the earlier ones? Do you have any info on the weights and dimensions of the Orpheus family?
By: - 5th February 2008 at 00:57 Permalink - Edited 1st January 1970 at 01:00
Orpheus [Bristol Siddley] Airflow: 84 lb/sec
model date thrust weight length diameter SFC
Or.1 (Prototype) 1955 3,285 lb --- 73” 32.4”
Or.2/701 (Gnat F.1/Finland) 1957 4,500 lb 790 lb 73” 32.4” 1.057
Or.2/701-01 (India Gnat F.1/Ajeet) 1958 4,700 lb 790 lb 73” 32.4” 1.057
Or.2/703 (HAL HF-24) 1960 4,850 lb 790 lb 73” 32.4” 1.057
Or.3/801 (Etendard VI) 1957 4,850 lb 825 lb 75.45” 32.4” 1.080
Or.3/803 (G.91 series) 1958 5,000 lb 825 lb 75.45” 32.4” 1.080
Or.3/805 (Fuji T-1A) 1958 4,000 lb 825 lb 75.45” 32.4” 1.080
Or.4/100-04 (Gnat T.1 UK) 1959 4,230 lb 900 lb 75.5” 32.4” .964
Or.4/101 (Gnat T.1 UK) 1960 4,520 lb 900 lb 75.5” 32.4” .964
Or.500 (C-119) 1961 5,750 lb --- --- 32.4” ---
Or.12 (Prototype) 1959 6,810 lb 1,170 lb 82.7” 32.4” .976
Or.12R (Prototype) {T/O only} 1959 6,810 lb {8,170 lb} 1,560 lb {1,479 lb} 32.4” .976/1.62
Correction to my earlier post... the Or.12R had both all-altitude afterburner (reheat) and take-off-only reheat versions. The all-altitude version has the higher weight shown above, and has a thrust listed only as "more than 9,000 lb (4,080 kg) thrust".
If you wish, I can send you a scan of the Jane's All the World's Aircraft engine section listing on the Orpheus. If I put it on Photobucket, it will get shrunk beyond readability (1,572 kb jpeg).
By: - 5th February 2008 at 07:41 Permalink - Edited 1st January 1970 at 01:00
No need to Badger. This information you have posted is perfect. Thank you very much for your effort.:) Wonder why its obvious British competitor, the Viper, is still around whilst the Orpheus is not?
By: - 5th February 2008 at 07:53 Permalink - Edited 1st January 1970 at 01:00
There is one under rebuild for flight in Germany but is due to relocate to the US in the future, website http://classic-jets.com/
By: - 6th February 2008 at 01:19 Permalink - Edited 1st January 1970 at 01:00
Well, the Viper is in the Jet Provost... and there are Orpheus flying in Gnats.
They were not really competitors, as they were in different thrust classes... at least until the late 1960s versions of the Viper. The Viper started out at half the thrust of the Orpheus.
I suspect that if the Orpheus had been in a civil aircraft like the Viper was (HS 125), or in multiple trainers used by many nations (Jet Provost/MB 326) then it would have been upgraded as well... as shown by the Or.12 prototypes.
As its primary use was in the Gnat, and the Japanese T-1A trainer, there was less demand for upgraded versions that took advantage of the improved materials and efficiency designs developed in the 1960s.
Viper 100 (1954): 1,640-1,900 lb thrust, 515 lb, 68.72” long, 24.55” wide, 28” high; Jet Provost
Viper 200 (1960): 2,000-2,700 lb thrust, 570-710 lb, 64” long, 24.55” wide, 28” high; Jet Provost, Soko Galeb, Shackleton, MB 326
Viper 500 (1962/1966): 3,000-3,410 lb thrust, 730-815 lb, 71.1” long (85" with thrust reverser), 24.55” wide, 28” high; HS.125, Soko Jastreb, BAC 167, MB 326GB
Viper 600 (1969): 3,700-4,000 lb thrust, 810-830 lb, 71.1” long (89" with thrust reverser), 24.55” wide, 28” high; HS.125-600, MB 326K
By: - 6th February 2008 at 20:42 Permalink - Edited 1st January 1970 at 01:00
Just reading the list of users, cancelled orders and evaluators.
I have seen pics of a GR-91 in Greek markings and one in American markings, but does anyone have any in Turkish and Norwegian markings?
Posts: 36
By: MIG-21bis - 1st February 2008 at 13:29
Very interested in Fiat G91Y recently, but found it very hard to get some detail information about it. Anyone can supply sth. detail or related web site?
Thanks a lot!