Pihero From France, joined Jan 2005, 3496 posts, RR: 72 Reply 1, posted (4 years 12 months 3 days 1 hour ago) and read 3050 times:
Not a very well known story, ThreeFourThree.
There was once a genius called Jean Bertin...Unrecognised of course.
Among other inventions like the "Aerotrain", applications on hoovercraft like the "Terraplane", he designed the first *jet deviation device* in the early fifties while working for SNECMA.
The first application, on the "Goblin" turbojet of a DH "Vampire" was successfully fight-tested on 26 July 1952.
The first civilian application found it's way on the Boeing 707, a rather complicated ensemble of thrust reverser and noise suppressing pipes.
As far as I know, it was very early a feature of the airplane and was needed for certification, therefore not an option.
Another matter of interest is that the 727 engine position and reverser was tested on the "Dash 80".
Rwessel From United States of America, joined Jan 2007, 1991 posts, RR: 2 Reply 2, posted (4 years 12 months 2 days 6 hours ago) and read 2879 times:
Many of the big piston powered airliners had reverse pitch available for their propellers. Actually almost all aircraft with variable pitch propellers have a reverse position, since it's trivial to add at that point, and it's useful.
Pihero From France, joined Jan 2005, 3496 posts, RR: 72 Reply 4, posted (4 years 12 months 1 day 22 hours ago) and read 2805 times:
Sorry, guys,
Semantics are not my forte.
The way I saw the question, the subject is about jet engines.
The reverse pitch option has never been called a thrust reverser in my dictionary.The propeller effect is more a *pull* than a *thrust*.
LAPA_SAAB340 From Spain, joined Aug 2001, 389 posts, RR: 5 Reply 5, posted (4 years 12 months 1 day 19 hours ago) and read 2754 times:
Quoting Pihero (Reply 1): The first civilian application found it's way on the Boeing 707, a rather complicated ensemble of thrust reverser and noise suppressing pipes.
I think they were used on the DH Comet first. Don't know if the original Comet 1 had them, but the RR Avon-powered versions had reversers on 2 of the engines.
Quoting Rwessel (Reply 2): Many of the big piston powered airliners had reverse pitch available for their propellers. Actually almost all aircraft with variable pitch propellers have a reverse position, since it's trivial to add at that point, and it's useful.
Some of the airliners powered by radial engines did have reverse pitch, but aside from those reverse pitch tends to be the exception rather than the rule with most piston engine aircraft. Also many early turboprop aircraft did not have reverse pitch.
AirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 26 Reply 6, posted (4 years 11 months 4 weeks 1 day 13 hours ago) and read 2576 times:
KELPkid From United States of America, joined Nov 2005, 5934 posts, RR: 4 Reply 7, posted (4 years 11 months 4 weeks 1 day 13 hours ago) and read 2575 times:
Negative. Feathering the prop is turning the blades so that they are 90 degrees to the slipstream, and is done to reduce drag when you loose a mill in a mult-engined bird. Reversing pitch is turning the blades so that the propeller is producing thrust in the opposite direction to the usual direction.
If you think of the propeller blades as spinning airfoils (which they are), then you see how this makes sense
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 8, posted (4 years 11 months 4 weeks 1 day ago) and read 2464 times:
Quoting KELPkid (Reply 7): Negative. Feathering the prop is turning the blades so that they are 90 degrees to the slipstream, and is done to reduce drag when you loose a mill in a mult-engined bird. Reversing pitch is turning the blades so that the propeller is producing thrust in the opposite direction to the usual direction.
Thats correct.Feathering produces "almost" no thrust.
regds
MEL
Asturias From Spain, joined Apr 2006, 1934 posts, RR: 17 Reply 9, posted (4 years 11 months 4 weeks 17 hours ago) and read 2433 times:
I can't agree that props produce thrust. Jets produce thrust, their power measured in N, props produce work measured in W.
Quoting Pihero (Reply 4): The reverse pitch option has never been called a thrust reverser in my dictionary.The propeller effect is more a *pull* than a *thrust*.
AirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 26 Reply 10, posted (4 years 11 months 4 weeks 16 hours ago) and read 2418 times:
Quoting KELPkid (Reply 7): Feathering the prop is turning the blades so that they are 90 degrees to the slipstream,
Which I already know that. They taught us that in A&P program in the Propellers class. Just wanted to double check. I don't deal with Propellers.
A Safe Flight Begins With Quality Maintenance On The Ground.
Santhosh From India, joined Sep 2001, 542 posts, RR: 1 Reply 11, posted (4 years 11 months 3 weeks 5 days 2 hours ago) and read 2255 times:
While dealing with a one engine out situation in a twin engine aircraft. Do pilots deploy the reverser on the other running engine upon landing or just simply brake since the activation of the reverser would cause the moment arm which would tend the aircraft to deviate off the course?
DashTrash From United States of America, joined Aug 2006, 1314 posts, RR: 4 Reply 12, posted (4 years 11 months 3 weeks 4 days 17 hours ago) and read 2210 times:
Quoting Santhosh (Reply 11): While dealing with a one engine out situation in a twin engine aircraft. Do pilots deploy the reverser on the other running engine upon landing or just simply brake since the activation of the reverser would cause the moment arm which would tend the aircraft to deviate off the course?
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 13, posted (4 years 11 months 3 weeks 4 days 17 hours ago) and read 2193 times:
Actually "N" in jet engines is the measurement of the rotational speed of the engine rotors, usually expressed as a percentage of their total rated RPM. The thrust represented by the N1 value is calculated, not measured.
True EPR, the actual comparison of PT1 and PT7 comes closer to actual measurement of thrust but still requires the charts to know the relative area of intake and exhaust.
Quoting Asturias (Reply 9): I can't agree that props produce thrust.
Well, in discussions of the "four forces" in flight, they do produce the one opposite "drag" so if you have a better name for that perhaps we could change convention. One might find fault with any of the usual expressions but they have the virtue of being comprehensible to student and professional alike.
Happiness is not seeing another trite Ste. Maarten photo all week long.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 15, posted (4 years 11 months 3 weeks 4 days 16 hours ago) and read 2176 times:
Personally I think they move by propelling air rearward. The air, in turn pushes the surface of the earth in that direction. As a side effect they cool the pilot.
An Army instructor argued that the propeller on the L-19 (or O-1) Bird Dog was a pusher as it pushed against the underside of the bolt heads attaching it to the crankshaft flange. I countered that it pulled equally against the underside of the nut behind that flange. We never did resolve that.
Happiness is not seeing another trite Ste. Maarten photo all week long.
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 16, posted (4 years 11 months 3 weeks 4 days 15 hours ago) and read 2168 times:
AIRLINERS.NET CREW HEAD DATABASE EDITOR
Quoting SlamClick (Reply 15): An Army instructor argued that the propeller on the L-19 (or O-1) Bird Dog was a pusher as it pushed against the underside of the bolt heads attaching it to the crankshaft flange. I countered that it pulled equally against the underside of the nut behind that flange. We never did resolve that.
I wonder if, through the entirety of aviation, anyone has ever mounted a propeller on each end of a single crankshaft. This would result in a pusher and puller configuration.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 17, posted (4 years 11 months 3 weeks 4 days 15 hours ago) and read 2166 times:
Quoting 2H4 (Reply 16): anyone has ever mounted a propeller on each end of a single crankshaft.
Of course you are well aware of historical examples of tractor and pusher propellers installed on the same nacelle but driven by two engines.
Single crankshaft? Where would the pilot sit?
Happiness is not seeing another trite Ste. Maarten photo all week long.
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 18, posted (4 years 11 months 3 weeks 4 days 15 hours ago) and read 2165 times:
AIRLINERS.NET CREW HEAD DATABASE EDITOR
Quoting SlamClick (Reply 17): Single crankshaft? Where would the pilot sit?
Same place. The engines would be out on the wings.
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 20, posted (4 years 11 months 3 weeks 4 days 13 hours ago) and read 2125 times:
Quoting SlamClick (Reply 13): Quoting Asturias (Reply 9):
their power measured in N
Actually "N" in jet engines is the measurement of the rotational speed of the engine rotors
Suspect Asturias means Newtons, but more usually it would be in kN, or of course old fashioned lbs.
Quoting Asturias (Reply 9): props produce work measured in W.
Propeller engine output is shaft power, measured in shp or kW. Work is not.
However a propeller itself certainly does produce thrust. It is what pushes (or pulls) the aircraft along.
Quoting Pihero (Reply 14): I am for *pull* or *traction*, both physically and thermodynamically correct, aren't they ?
Certainly not traction, which requires friction to work. "Pull" maybe, but I would have thought a pilot would much prefer a bit of "thrust".
The glass isn't half empty, or half full, it's twice as big as it needs to be.
Bond007 From United States of America, joined Mar 2005, 5098 posts, RR: 8 Reply 22, posted (4 years 11 months 3 weeks 4 days 9 hours ago) and read 2089 times:
Quoting Jetlagged (Reply 20): Certainly not traction, which requires friction to work.
You mean friction .. like friction against the air?
Isn't that why the prop displaces the air ... and doesn't displace as much 'thin' air
Jimbo
I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
Jetlagged From United Kingdom, joined Jan 2005, 2452 posts, RR: 17 Reply 23, posted (4 years 11 months 3 weeks 3 days 10 hours ago) and read 2017 times:
Quoting Bond007 (Reply 22): You mean friction .. like friction against the air?
Isn't that why the prop displaces the air ... and doesn't displace as much 'thin' air
A prop would still work without friction. It creates lift in the forward direction, which becomes thrust.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 24, posted (4 years 11 months 3 weeks 3 days 10 hours ago) and read 2013 times:
Quoting Bond007 (Reply 22): .. like friction against the air?
Or a conveyor belt.
Happiness is not seeing another trite Ste. Maarten photo all week long.
26 Bond007: ... and that lift is directly proportional to the air density ...only if the speed of the propellor matches the speed of the belt .... Jimbo
27 2H4: Not to mention the number of hovering birds in the cabin. 2H4
28 WPIAeroGuy: What if the propellor and plane stays stationary and the air spins around the fuselage?
29 Bond007: Well, it's much more interesting for the passengers (and crew!), if the propellor stays stationary and the plane spins. I think that starts to happen
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