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First Thrust Reversers?  
User currently offlineThreeFourThree From Australia, joined Nov 2007, 215 posts, RR: 0
Posted (6 years 3 months 3 weeks 6 days 23 hours ago) and read 3662 times:

Does anyone know when thrust reversers were first used and was it an option?

31 replies: All unread, showing first 25:
 
User currently offlinePihero From France, joined Jan 2005, 4449 posts, RR: 76
Reply 1, posted (6 years 3 months 3 weeks 6 days 19 hours ago) and read 3615 times:
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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".



Contrail designer
User currently offlineRwessel From United States of America, joined Jan 2007, 2353 posts, RR: 2
Reply 2, posted (6 years 3 months 3 weeks 6 days 1 hour ago) and read 3443 times:
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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.

User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 3, posted (6 years 3 months 3 weeks 5 days 18 hours ago) and read 3394 times:

Was thinking just that.Reverse pitch propellers on the Piston Engined types should be the 1st of the T/Rs.

regds
MEL



Think of the brighter side!
User currently offlinePihero From France, joined Jan 2005, 4449 posts, RR: 76
Reply 4, posted (6 years 3 months 3 weeks 5 days 16 hours ago) and read 3369 times:
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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*.



Contrail designer
User currently offlineLAPA_SAAB340 From Spain, joined Aug 2001, 390 posts, RR: 4
Reply 5, posted (6 years 3 months 3 weeks 5 days 13 hours ago) and read 3318 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.


User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 6, posted (6 years 3 months 3 weeks 3 days 8 hours ago) and read 3140 times:



Quoting Rwessel (Reply 2):
...reverse pitch...

Isn't that the same as feathering the prop?



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineKELPkid From United States of America, joined Nov 2005, 6388 posts, RR: 3
Reply 7, posted (6 years 3 months 3 weeks 3 days 8 hours ago) and read 3139 times:



Quoting AirframeAS (Reply 6):


Isn't that the same as feathering the prop?

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  Smile



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 8, posted (6 years 3 months 3 weeks 2 days 19 hours ago) and read 3028 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



Think of the brighter side!
User currently offlineAsturias From Spain, joined Apr 2006, 2156 posts, RR: 16
Reply 9, posted (6 years 3 months 3 weeks 2 days 12 hours ago) and read 2997 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*.

This I agree with.

asturias



Tonight we fly
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 10, posted (6 years 3 months 3 weeks 2 days 11 hours ago) and read 2982 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.
User currently offlineSanthosh From India, joined Sep 2001, 545 posts, RR: 1
Reply 11, posted (6 years 3 months 2 weeks 6 days 21 hours ago) and read 2819 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?

Regards
George



Happy Landing
User currently offlineDashTrash From United States of America, joined Aug 2006, 1528 posts, RR: 2
Reply 12, posted (6 years 3 months 2 weeks 6 days 12 hours ago) and read 2774 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?

Depends on the airplane.


User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 13, posted (6 years 3 months 2 weeks 6 days 11 hours ago) and read 2757 times:



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, 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.
User currently offlinePihero From France, joined Jan 2005, 4449 posts, RR: 76
Reply 14, posted (6 years 3 months 2 weeks 6 days 11 hours ago) and read 2751 times:
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Quoting SlamClick (Reply 13):
they do produce the one opposite "drag" so if you have a better name for that perhaps we could change convention.

I am for *pull* or *traction*, both physically and thermodynamically correct, aren't they ?
 duck 



Contrail designer
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 15, posted (6 years 3 months 2 weeks 6 days 10 hours ago) and read 2740 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.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 59
Reply 16, posted (6 years 3 months 2 weeks 6 days 10 hours ago) and read 2732 times:
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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.

2H4



Intentionally Left Blank
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 17, posted (6 years 3 months 2 weeks 6 days 10 hours ago) and read 2730 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.
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 59
Reply 18, posted (6 years 3 months 2 weeks 6 days 10 hours ago) and read 2729 times:
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Quoting SlamClick (Reply 17):
Single crankshaft? Where would the pilot sit?

Same place. The engines would be out on the wings.  Wink

2H4



Intentionally Left Blank
User currently offlinePihero From France, joined Jan 2005, 4449 posts, RR: 76
Reply 19, posted (6 years 3 months 2 weeks 6 days 10 hours ago) and read 2721 times:
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Quoting SlamClick (Reply 15):
The air, in turn pushes the surface of the earth in that direction. As a side effect they cool the pilot.



Quoting SlamClick (Reply 15):
I countered that it pulled equally against the underside of the nut behind that flange. We never did resolve that.

This is getting too hot for me.

I need a fan !




 cheerful   hot 



Contrail designer
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2556 posts, RR: 24
Reply 20, posted (6 years 3 months 2 weeks 6 days 8 hours ago) and read 2689 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".  Wink



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlinePihero From France, joined Jan 2005, 4449 posts, RR: 76
Reply 21, posted (6 years 3 months 2 weeks 6 days 7 hours ago) and read 2679 times:
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Not you too !!!!!  Wink


 Angry  Angry  Angry  Angry



Contrail designer
User currently offlineBond007 From United States of America, joined Mar 2005, 5417 posts, RR: 8
Reply 22, posted (6 years 3 months 2 weeks 6 days 3 hours ago) and read 2653 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  Wink

Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2556 posts, RR: 24
Reply 23, posted (6 years 3 months 2 weeks 5 days 5 hours ago) and read 2581 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.
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 24, posted (6 years 3 months 2 weeks 5 days 5 hours ago) and read 2577 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.
25 Starlionblue : Slay him.
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
30 Jetlagged : Amongst other things of course.
31 Osiris30 : BWHAHAHAHAHHA.. well played And another one Great thread guys, thanks for making me smile
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