Mrocktor From United States of America, joined Jan 2005, 1645 posts, RR: 51 Reply 1, posted (6 years 3 months 1 week 1 day 10 hours ago) and read 2260 times:
Not sure what you mean about two engines in one. If you are talking about the fact that modern turbofans have two rotating groups with concentric axles, then yes. Early jet engines had only one rotating group exactly as you describe.
KELPkid From United States of America, joined Nov 2005, 5932 posts, RR: 4 Reply 4, posted (6 years 3 months 1 week 1 day 4 hours ago) and read 2166 times:
Quoting Airfoilsguy (Reply 3): If you take the blades off of a turboprop you would get a similar scenario. Even at max thrust I don't think you would get far.
I was talking to a Cessna Caravan salesman at an airshow once. They had brought a Caravan on floats to the show, and I was talking to him about it (of course, I'd never in my wildest dreams be able to afford one ), and he mentioned that many floatplane pilots have a little difficulty transitioning to the floatplane version of the Caravan because with the throttle at idle, the engine still produces enough thrust to keep the Caravan in motion on the water...not sure if it's the idle thrust that the prop produces or the thrust coming out the PT6's exhaust...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
HangarRat From United States of America, joined Jul 2005, 626 posts, RR: 0 Reply 5, posted (6 years 3 months 1 week 1 day 4 hours ago) and read 2156 times:
Quoting KELPkid (Reply 4): not sure if it's the idle thrust that the prop produces or the thrust coming out the PT6's exhaust...
I remember reading when the floatplane version of the Caravan was introduced that the tailpipe puts out about 40 pounds of thrust.
Speedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0 Reply 6, posted (6 years 3 months 1 week 20 hours ago) and read 2066 times:
Quoting Chksix (Reply 2): The old low bypass engines (737-100, DC-9) were "pushing" through the power of the jet thrust only.
The JT8-D on those planes were, as you say, low bypass engines, and had a bypass ratio of something around 1:1 give or take. Any turbo fan, including low bypass ones like the JT8-D, produce some of the thrust via the fan. Only turbojets rely on jet thrust only.
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
Gemuser From Australia, joined Nov 2003, 5217 posts, RR: 6 Reply 7, posted (6 years 3 months 1 day 19 hours ago) and read 1835 times:
I think what you are describing is a "turbo jet" in which ALL of the air which passed thru the engine entered the combustion camber, was burnt with fuel, then expelled out the exhaust. These were used on all the early airliners such as the Commet, B707-120 series and DC8s (early series). They were total fuel hoggs. They were replaced by the low by pass engines referred to in reply 6, where only some of the air entered the combustion chamber and the rest by passed it and went directly to the jet. Hence turbo jet, fan jet, low by pass ratio and high by pass ratio engines.
As a point of intrest the recently restored QF B707-138 VH-XBA was built with turbo jet engines, which were later replaced with early low bypass fan jet engines. When that was done it became a B707-138B.
Scooter01 From Norway, joined Nov 2006, 1154 posts, RR: 8 Reply 8, posted (6 years 3 months 1 day 16 hours ago) and read 1815 times:
Quoting HangarRat (Reply 5): I remember reading when the floatplane version of the Caravan was introduced that the tailpipe puts out about 40 pounds of thrust.
The RR Dart engines on the F.27 (depending on type) gave additional 350-500 lbst. from the exhaust at take-off power.
As a curiosity I can also mention that on the first two Bell 204 helicopters that came to Norway had the exhaust pointing sideways. I remember how the pilots were bragging about how much faster they had become after they were modified to having the tailpipe pointing straight back.
Scooter
"We all have a girl and her name is nostalgia" - Hemingway
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), and he mentioned that many floatplane pilots have a little difficulty transitioning to the floatplane version of the Caravan because with the throttle at idle, the engine still produces enough thrust to keep the Caravan in motion on the water...not sure if it's the idle thrust that the prop produces or the thrust coming out the PT6's exhaust...
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