Rob Arndt
2006-09-25 15:19:49 UTC
Loading Image...
Loading Image...
F-12, R-12 Rainbow 1946 = Long-range photo-recon. 7pClwM rg; four
28-cyl 3250hp P&W R-4360-31 Wasp Majors; span: 129'2" length: 93'10"
load (est): 10,000# v: 450/400/104 range: 4100 ceiling: 41,000'.
Alexander Kartveli; ff (as XF-12A): 7/2/46. Sleek flying photo lab
complete with three camera and a darkroom. Initially planned as a
post-war transport, the only two built went to USAAF as XF-12A, their
first four-engine aircraft designed specifically for photo-recon
duties. Redesignated as XR-12A in June 1948. POP: 2 [44-91002/91003],
and a contract for 6 cancelled. Disposition of the first one unknown;
the latter was destroyed in a crash at Eglin AFB on 11/7/48.
Prototypes for Republic XF-12 used a system to route exhaust and
supercharger and accessory waste gases to an oval "jet pipe" exhaust
installation on four R-4360-31s, which gained 250-300hp per engine.
Rather than having individual cowl flaps, the entire nacelle was
equipped with a sliding ring arrangement and internal variable-speed
fan for cooling air on the cylinder heads.
The Rainbow was purpose-built as a Strategic Reconnaissance
aircraft. USAAF/USAF decided to stay with the F-13 - modified B-29s,
redesignated RB-29s after 1948. XF-12s were significantly faster in
cruise than the F-13/RB-29s (220mph vs 380mph) with nearly 4000-mile
range and a service ceiling in excess of 40,000', and had an on-board
photo processing lab. The two prototypes were redesignated XR-12 by
1948. One is at the bottom of the Gulf of Mexico, the other ended as a
target at Aberdeen proving grounds in the late '40s or early '50s.
Republic proposed a 46-place passenger version with 7 crew, 400mph
over 3500 miles, but there were not enough orders to cover development
costs. I think Rainbows still holds the unofficial record for
four-engine piston speed at around 460mph. The design goal was
sometimes referred to as "flying on all fours" - 4 engines, 400mph
cruise, 4000 miles at 40,000'. (- Bill Zorn via Richard E Gillespie
10/10/00)
Rob
Loading Image...
F-12, R-12 Rainbow 1946 = Long-range photo-recon. 7pClwM rg; four
28-cyl 3250hp P&W R-4360-31 Wasp Majors; span: 129'2" length: 93'10"
load (est): 10,000# v: 450/400/104 range: 4100 ceiling: 41,000'.
Alexander Kartveli; ff (as XF-12A): 7/2/46. Sleek flying photo lab
complete with three camera and a darkroom. Initially planned as a
post-war transport, the only two built went to USAAF as XF-12A, their
first four-engine aircraft designed specifically for photo-recon
duties. Redesignated as XR-12A in June 1948. POP: 2 [44-91002/91003],
and a contract for 6 cancelled. Disposition of the first one unknown;
the latter was destroyed in a crash at Eglin AFB on 11/7/48.
Prototypes for Republic XF-12 used a system to route exhaust and
supercharger and accessory waste gases to an oval "jet pipe" exhaust
installation on four R-4360-31s, which gained 250-300hp per engine.
Rather than having individual cowl flaps, the entire nacelle was
equipped with a sliding ring arrangement and internal variable-speed
fan for cooling air on the cylinder heads.
The Rainbow was purpose-built as a Strategic Reconnaissance
aircraft. USAAF/USAF decided to stay with the F-13 - modified B-29s,
redesignated RB-29s after 1948. XF-12s were significantly faster in
cruise than the F-13/RB-29s (220mph vs 380mph) with nearly 4000-mile
range and a service ceiling in excess of 40,000', and had an on-board
photo processing lab. The two prototypes were redesignated XR-12 by
1948. One is at the bottom of the Gulf of Mexico, the other ended as a
target at Aberdeen proving grounds in the late '40s or early '50s.
Republic proposed a 46-place passenger version with 7 crew, 400mph
over 3500 miles, but there were not enough orders to cover development
costs. I think Rainbows still holds the unofficial record for
four-engine piston speed at around 460mph. The design goal was
sometimes referred to as "flying on all fours" - 4 engines, 400mph
cruise, 4000 miles at 40,000'. (- Bill Zorn via Richard E Gillespie
10/10/00)
Rob