bigphilnyc
Posts: 3874
Joined: Sat Jan 19, 2002 10:43 pm

Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 6:20 am

From my dock at LGA, it seems as though older rear engine aircraft (MD-80, DC-9, 727, etc) don't climb as fast as other planes, even larger ones.

I see that 757s are already 800 feet up when they go over my head on departures, while 727s and MD-80 seem to only be about 200 over my head sometimes.

Is there some relation with rear engine planes and a slower climb? Is it that their engines are older? Is it the physics of the push coming fromt he back?

Weird stuff.
Phil Derner Jr.
 
YVR74
Posts: 139
Joined: Fri Sep 13, 2002 3:38 am

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 6:42 am

I don't know about rear engine airplanes having a slow climb or not, but I do have a remark in reference to your comments about the 757.

I'm sure there are people who might know some technical reason why, and my knowledge is only from that as a passenger, but the steepest climbs I have ever experienced while onboard an aircraft have been on a 757. Once on a Delta 757 flight out of DFW, the angle of climb was so steep that I figured something must surely have gone wrong with the airplane and that we would fall out of the sky. It was incredible.
 
bigphilnyc
Posts: 3874
Joined: Sat Jan 19, 2002 10:43 pm

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 6:46 am

Yeah, I know that 757s do have fast climbs, I should have used aanother plane as a reference.
Phil Derner Jr.
 
MD88Captain
Posts: 1224
Joined: Wed Nov 14, 2001 9:50 am

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 9:57 am

The position of the engines have nothing to do with the takeoff performance of aircraft. It has more to do with aircraft wieght, wing design, thrust available, etc. Where the engines are placed does affect aircraft handling but not takeoff performance. The aircraft you mention are either underpowered (727) or have a small wing (makes less lift). The 757 is a rocket on takeoff because its wind make alot of lift and it makes a bunch of thrust.
 
flyf15
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Joined: Tue May 18, 1999 11:10 am

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 10:01 am

Some of the highest powered airliners out there are actually rear engined. Specifically the MD-90 and the CRJ. Not always the best climbers though, do to their wing design.
 
rendezvous
Posts: 531
Joined: Sun May 20, 2001 9:14 pm

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 10:09 am

The Boeing 717 climbs like a rocket too.
 
Guest

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 10:17 am

Actually, the time to climb records for turbine powered aircraft are, for the most part, held by rear-engined aircraft.
 
POSITIVE RATE
Posts: 2121
Joined: Sun Sep 16, 2001 11:31 am

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 10:31 am

The 727-200 was a bit of a slow climber maybe due to being slightly underpowered, but the MD-80, 717, MD-90 seem to climb pretty quick.
 
Guest

RE: Rear Engine Aircraft: Slow Climb?

Sun Sep 22, 2002 12:40 pm

Back in my airline days I once asked a captain how long he had been flying 727's. His answer, "Twelve years - 6 years in climb, 3 years in cruise, and 3 years in descent."  Innocent
Jetguy

 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Rear Engine Aircraft: Slow Climb?

Mon Sep 23, 2002 12:53 pm

Excess thrust, and the corresponding thrust to weight ratio, is the single largest determinant of climb performance; not engine placement (didn't we just cover this on the A340???)

 
bragi
Posts: 212
Joined: Sun May 27, 2001 5:17 am

RE: Rear Engine Aircraft: Slow Climb?

Mon Sep 23, 2002 5:58 pm

About the B757; it´s so powerful on takeoff, that some pilots I know and who fly it, sometimes climb much faster than the cabin has time to pressurise, so after a steep climb (in ferry flights) , they lower the nose and let the cabin catch up!
Muhammad Ali: "Superman don’t need no seat belt." Flight Attendant: "Superman don’t need no airplane, either."
 
BR715-A1-30
Posts: 6525
Joined: Thu May 30, 2002 9:30 am

RE: Rear Engine Aircraft: Slow Climb?

Wed Sep 25, 2002 3:18 pm

The Boeing 717 climbs like a rocket too.

You got that right!!!! She climbs faster than the MD-90 in my opinion. May have been that the Captain on the MD-90 didn't apply full thrust, but the 717 IMO climbed faster than the MD-90
Puhdiddle
 
cv640
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Joined: Wed Aug 30, 2000 8:10 pm

RE: Rear Engine Aircraft: Slow Climb?

Wed Sep 25, 2002 7:50 pm

The Lear and Gulfstreams, along with most opther corporate aircraft, are rear engined aircraft and have numerous records in the time to cimb area. Total thrust and woing design, along with weight, are the real factors for climb rates.
 
Boeing Nut
Posts: 5078
Joined: Fri Feb 23, 2001 2:42 am

RE: Rear Engine Aircraft: Slow Climb?

Thu Sep 26, 2002 8:41 am

CV640 is correct. I remember reading an article on the Gulstream IV-SP (a.k.a. Gulfstream 400) on a flight that broke several climb records. The fuel load was light, but, on takeoff, the aircraft was powered up to full thrust with brakes applied. The Tays were so strong that even with the brakes applied, the G-IV-SP was skidding. Now those are some strong engines!!!!
I'm not a real aeronautical engineer, I just play one on Airliners.net.
 
MD-90
Posts: 7835
Joined: Mon Jan 17, 2000 12:45 pm

RE: Rear Engine Aircraft: Slow Climb?

Fri Sep 27, 2002 2:19 am

I'd say the 757 climbs fast because it's wing is not optimized for high speed cruise (the sweepback angle isn't that high). The 727 has a lot of sweep, and was optimized for high speed cruising, not maximum lift at low speeds. The MD-90 also has been stretched so much from what the wing was originally designed to lift, it's not surprising if it doesn't climb all that terribly well (although the steepest climb I've ever seen was on one of those tv reality shows that had an SAS MD-80, I dunno, maybe clearing a mountain or something but I've never seen an AOA that steep on any big jet before or since).
 
EssentialPowr
Posts: 1646
Joined: Wed Sep 06, 2000 10:30 pm

RE: Rear Engine Aircraft: Slow Climb?

Fri Sep 27, 2002 6:28 am

If one runs the numbers, the 757 typically has higher thrust to weight ratios than other 121 a/c...the 717 and MD90 are in the same ballpark.

If one compares a DC9-30 w/ a 717, the wing differences are minimal...but the thrust to weight ratio is greatly increased in the 717 as compared to its older brother. One could have made the most comprehensive change to the DC9 wing possible; but if max gross weights and thrust were held constant, the climb performance wouldn't change nearly as significantly as is has with the higher thrust engines of the 717. Climb performance is largely a function of excess thrust.

Also, the 328 jet is an excellent climber...corporate jets and fighters have engines near their centerlines for a couple of big reasons...for fighters, it keeps the size of the vertical tail(s) to a minimum in case of a failed engine. For corporate a/c, engines slung under the wing force raise the profile of the a/c up far enough such that just about anything that needs to be done on the a/c from daily maint to loading pax would require ladders or larger airstairs than typically used, which detracts from the mission flexability of a corporate a/c at remote airports.


cheers-
 
MagicMan_841
Posts: 177
Joined: Sat Jan 19, 2002 8:12 am

RE: Rear Engine Aircraft: Slow Climb?

Sat Sep 28, 2002 1:58 pm

CRJs and ERJs are bombs. They're pretty fast climbers!

M@g!¢  Yeah sure

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