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Author Topic: Beyond the Rainbow: Republic Turboprop and Jet Airliners  (Read 21672 times)

Offline boxkite

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Beyond the Rainbow: Republic Turboprop and Jet Airliners
« on: August 09, 2006, 02:33:33 pm »
This Republic "Rainbow" development with a 35° swept wing was published in a German aviation magazine in the 1950s (no idea which one). Is anybody able to identify the type and to give further information?

Offline pometablava

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #1 on: August 09, 2006, 03:09:48 pm »
Many Thanks Boxkite!

It is a very interesting project. Republic derivative from its fine Rainbow was designated RC-2. This is clearly a step beyond, intended to get access to the jet airliner market in the 50's. A probable manufacturer designation could be RC-4 (the RC-3 was the Seabee from 1945).

What do you think Lark?

Offline lark

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #2 on: August 10, 2006, 06:24:23 am »
There was a step inbetween.A turboprop development of the Rainbow.I have it
in an old French magazine of the late fifties but I have to dig (very) deep.
As far as I remember the article gives no info of designations.

Offline devi

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #3 on: August 10, 2006, 07:06:12 am »
   Hi Boxkite.
 In what number and in what to page it is told about Republic Rainbow (jet engined version).

Offline boxkite

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #4 on: August 10, 2006, 12:32:21 pm »
Sorry, but I cannot give a satisfying answer. I've got the Republic image as a Xerox copy from a friend a few years ago. Unfortunately he is too lazy to make notices of the source. My further inquiry wasn't successfully. He only remembers, that 'it was published in a German magazine in the 1950s'.  :(

[So SPF members please don't forget the source of your knowledge to help for further study. Thanks a lot.]

Offline lark

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #5 on: August 11, 2006, 11:10:57 am »
This illustration -with the " Rainbow" and the turboprop version -
appeared in "L' Echo des Ailes" of 10 June 1950.
It was part of the illustrations in an article about the future
of air transport.The turboprop version should have a less sleek
wing and almost the same fuselage.The all jet retained only the basics
of the fuselage. no info was given about the designation.It seems that these illustrations are highly speculative...

Offline pometablava

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #6 on: August 13, 2006, 02:16:40 pm »
Dear Friends Boxkite and Lark.

My especulative RC-4 designation for this project it's not correct. My friend David from The Nederlands sent me a photocopy with the real RC-4 which corresponds to an aircraft with a layout very close to the Fokker F.27. This design dates back from the 60's so now I think that the "jet RC-2" could have retained the RC-2 designation.

Offline elmayerle

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #7 on: August 13, 2006, 03:54:58 pm »
This illustration -with the " Rainbow" and the turboprop version -
appeared in "L' Echo des Ailes" of 10 June 1950.
It was part of the illustrations in an article about the future
of air transport.The turboprop version should have a less sleek
wing and almost the same fuselage.The all jet retained only the basics
of the fuselage. no info was given about the designation.It seems that these illustrations are highly speculative...


If you can find it, a scan of the illustration of the turboprop version would good to see.  I'm just wondering what turboprops were proposed?  IMHO, the use of Darts, Tynes, or similar engines rather than the Allison 501/T56 would suit the aesthetics better, but I'd be most interested in seeing any info available.

Offline Sentinel Chicken

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #8 on: August 13, 2006, 06:13:11 pm »
Are you sure they were going to use turboprops on the evolved Rainbow versions or VDTs? There was quite a bit of work on variable discharge turbines in those days- there was even a version of the B-36 (I think it was the B-36C) that was to have used VDTs.

Offline elmayerle

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #9 on: August 14, 2006, 09:10:21 pm »
Are you sure they were going to use turboprops on the evolved Rainbow versions or VDTs? There was quite a bit of work on variable discharge turbines in those days- there was even a version of the B-36 (I think it was the B-36C) that was to have used VDTs.

The basic Rainbow already used VDTs, that's one reason for the exhaust at the rear of the nacelle.

And, yes, the B-36C was a proposal for using VDTs on the B-36 in a tractor propeller configuration.

Offline Sentinel Chicken

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #10 on: August 15, 2006, 06:48:56 pm »
Are you sure they were going to use turboprops on the evolved Rainbow versions or VDTs? There was quite a bit of work on variable discharge turbines in those days- there was even a version of the B-36 (I think it was the B-36C) that was to have used VDTs.

The basic Rainbow already used VDTs, that's one reason for the exhaust at the rear of the nacelle.

And, yes, the B-36C was a proposal for using VDTs on the B-36 in a tractor propeller configuration.

The VDT (Variable Discharge Turbine) engine was a Pratt & Whitney R-4260-51 Wasp Major where the exhaust gases drove a GE CMH-2 turbosupercharger that had a clamshell nozzle that could modulate the thrust by varying the opening of the nozzle- hence the term VDT.*

The Republic XF-12/XR-12 Rainbow did have turbosupercharger exhaust that was used to add forward thrust but it wasn't a VDT- it had a slightly different Wasp Major model (the -31) and the exhaust drove two GE BM-4-5 turbosupercharger units (at lower speeds only one unit was engaged) which then exhausted via a fixed oval nozzle at the rear of the nacelle.**
 
*"Magnesium Overcast: The Story of the Convair B-36" by Dennis Jenkins, Chapter 3, p.54
**"Republic XF-12 Rainbow: All the Fours" from Wings of Fame Volume 3, p.29



Offline devi

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #11 on: August 30, 2006, 07:35:18 am »
  Hi lark.

 What number this magazine?("L' Echo des Ailes" of 10 June 1950)

 In what pages about the Republic "Rainbow"?

 And if it is possible, the name of article.
 

Offline lark

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #12 on: August 30, 2006, 12:01:34 pm »
Since I only have a part of the magazine , I cant give
you the issue number.

Title :" L'Amerique découvre l' Europe"
         (America discovers Europe)

pages :25-26-27 of 10 June 1950

Offline boxkite

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #13 on: June 02, 2007, 07:21:05 am »
Did we have an artwork of the turboprop Rainbow yet?

SOURCE: aero magazine 1958 (page 127)

Offline elmayerle

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Re: Beyond the Rainbow: Republic Turboprop and Jet Airliners
« Reply #14 on: June 02, 2007, 09:45:00 pm »
Did we have an artwork of the turboprop Rainbow yet?

SOURCE: aero magazine 1958 (page 127)

Going by the appearance of the engine nacelles, I'd say it's powered by Allison 501/T56 engines.