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cduluk
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Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 12:50 pm

Hi all:

I wanted to share something that i thought was interesting, and want to get your input.

We've all heard of B747s with a 5th engine, L-1011's with a 4th engine, etc but they've always been 'inoperative', just hanging there for the purpose of transporting for maintenance.

I stumbled on this image of an engine mounted on the rear fuselage of a Boeing 707, specifically reg: N70700 which was the actual PROTOTYPE Dash 80.

http://i66.tinypic.com/i4ej4n.jpg

It appears that it's an operational engine (note the S exhaust duct, re-directing hot gasses over the horizontal stabilizer).

The image didn't come with any captions, so I'm not sure what the purpose was. Any ideas?
My 'guess' is that it has something to do with designing the 727. I can see that the engine pod is tufted, so maybe they were testing airflow characteristics around the pod? But if so, why would they need the engine to be operative.. just to test airflow characteristics?

Thoughts?
 
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Moose135
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 2:11 pm

From:
http://airandspace.si.edu/collection...ifact.cfm?object=nasm_A19730272000

Quote:
Until its retirement in 1972, the Dash 80 tested numerous advanced systems, many of which were incorporated into later generations of jet transports. At one point, the Dash 80 carried three different engine types in its four nacelles. Serving as a test bed for the new 727, the Dash 80 was briefly equipped with a fifth engine mounted on the rear fuselage.
KC-135 - Passing gas and taking names!
 
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747classic
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 2:44 pm

Quoting cduluk (Thread starter):
We've all heard of B747s with a 5th engine, L-1011's with a 4th engine, etc but they've always been 'inoperative', just hanging there for the purpose of transporting for maintenance.

Pratt & Witney used one of it's two 747SP engine test beds in 2012 for testing of the PW1200G engine.

747SP with five (5) operating engines, see : http://www.youtube.com/watch?v=cIB7C5LfAi0
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
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vhqpa
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 3:03 pm

While not for the same purpose. Later Tridents had a fourth booster engine that was used for takeoff.

HS Trident 4th Engine? (by Boeing744 Feb 21 2006 in Civil Aviation)

Then there was the Mexicana 727-200s that had JATO rocket(s?) for hot and high engine out performance.
"There you go ladies and gentleman we're through Mach 1 the speed of sound no bumps no bangs... CONCORDE"
 
113312
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 4:40 pm

The picture is of the prototype "Dash 80" with an JT-8D engine mounted to test the pylon, cowl, and engine for the 727 program. Just one of many experimental configurations applied to this test aircraft. See Airlife's Classic Airliners Boeing 707/720 page 15 for an excellent inflight picture.
 
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litz
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 5:57 pm

Quoting vhqpa (Reply 3):
Then there was the Mexicana 727-200s that had JATO rocket(s?) for hot and high engine out performance.

Someone has to have video of this. Come on Internet, cough it up ....
 
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Moose135
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 6:49 pm

Images of a Mexicana 727 with rockets:

http://s25.photobucket.com/user/aloges/media/JATO.jpg.html

http://s168.photobucket.com/user/spe...icana%20JATO_2%20reseized.jpg.html

A poor quality video - looks like it was recorded off a TV screen - of a Boeing test:

http://www.youtube.com/watch?v=G7LErwBNobU

[Edited 2016-05-13 11:50:01]
KC-135 - Passing gas and taking names!
 
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longhauler
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Fri May 13, 2016 7:06 pm

Quoting 747classic (Reply 2):
Pratt & Witney used one of it's two 747SP engine test beds in 2012 for testing of the PW1200G engine.

Not to mention P&W Canada put a turboprop on the nose of a B720!


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Viscount724
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Sat May 14, 2016 2:48 am

Quoting longhauler (Reply 7):
Quoting 747classic (Reply 2):
Pratt & Witney used one of it's two 747SP engine test beds in 2012 for testing of the PW1200G engine.

Not to mention P&W Canada put a turboprop on the nose of a B720!

P&W Canada also put many of their turboprops in the nose of their ex-AC Viscount testbed for 17 years (1972-89). It was AC's 4th-last of 51 Viscounts (CF-TID).

http://1000aircraftphotos.com/Contributions/Visschedijk/2583L.jpg

And there was the Avro Lincoln bomber testbed with a R-R Tyne turboprop in the nose. This photo at the Farnborough Airshow in 1956 being flown with only the Tyne operating and the 4 Merlins shut down.

https://upload.wikimedia.org/wikipedia/commons/3/37/Rolls-Royce_Tyne_Avro_Lincoln_Farnborough_1956.jpg
 
Aircellist
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Sat May 14, 2016 5:19 am

Quoting longhauler (Reply 7):
Not to mention P&W Canada put a turboprop on the nose of a B720!

During a visit of that one, a test engineer (or so I believe) told me that the prop could pull the aircraft by itself, once it was in flight… I don't know whether it's true, or if it's been tested, but it's nice to imagine that (quite empty) plane as the biggest single-engined prop ever  
"When I find out I was wrong, I change my mind. What do you do?" -attributed to John Maynard Keynes
 
jetstar
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Sat May 14, 2016 2:37 pm

Around 1950 P&W used a B-17 and mounted a prototype T-34 turbo prop engine on the nose for inflight testing, you can see pictures of this airplane by doing a wikipedia search on the T-34 engine.

JetStar
 
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dlednicer
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RE: Boeing 707 With "tail-mounted Engine? It Existed!

Sun May 15, 2016 6:28 pm

There were two 5-engine Boeing 299Zs built - one for Pratt & Whitney and one for Curtiss Wright. The P&W example was later "Liberty Belle", which burned out after a crash landing in 2011. The CW example later became a water bomber and was lost in a crash in 1980, but is under rebuild in Urbana OH.

P&W:
http://www.airwar.ru/image/idop/bww2/b17g/b17g-8.jpg

CW:

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