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Rear Engine Aircraft: Slow Climb?  
User currently offlineBigPhilNYC From United States of America, joined Jan 2002, 4076 posts, RR: 54
Posted (11 years 11 months 2 weeks 4 days ago) and read 10079 times:

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.
16 replies: All unread, jump to last
 
User currently offlineYvr74 From Canada, joined Sep 2002, 52 posts, RR: 0
Reply 1, posted (11 years 11 months 2 weeks 4 days ago) and read 10023 times:

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.


User currently offlineBigPhilNYC From United States of America, joined Jan 2002, 4076 posts, RR: 54
Reply 2, posted (11 years 11 months 2 weeks 4 days ago) and read 10016 times:

Yeah, I know that 757s do have fast climbs, I should have used aanother plane as a reference.


Phil Derner Jr.
User currently offlineMD88Captain From United States of America, joined Nov 2001, 1330 posts, RR: 20
Reply 3, posted (11 years 11 months 2 weeks 3 days 21 hours ago) and read 9957 times:

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.

User currently offlineFlyf15 From , joined Dec 1969, posts, RR:
Reply 4, posted (11 years 11 months 2 weeks 3 days 21 hours ago) and read 9937 times:

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.

User currently offlineRendezvous From New Zealand, joined May 2001, 516 posts, RR: 0
Reply 5, posted (11 years 11 months 2 weeks 3 days 21 hours ago) and read 9914 times:

The Boeing 717 climbs like a rocket too.

User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 6, posted (11 years 11 months 2 weeks 3 days 20 hours ago) and read 9908 times:

Actually, the time to climb records for turbine powered aircraft are, for the most part, held by rear-engined aircraft.


User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 7, posted (11 years 11 months 2 weeks 3 days 20 hours ago) and read 9906 times:

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.

User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 8, posted (11 years 11 months 2 weeks 3 days 18 hours ago) and read 9865 times:

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



User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 9, posted (11 years 11 months 2 weeks 2 days 18 hours ago) and read 9740 times:

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???)



User currently offlineBragi From Iceland, joined May 2001, 218 posts, RR: 0
Reply 10, posted (11 years 11 months 2 weeks 2 days 13 hours ago) and read 9728 times:

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."
User currently offlineBR715-A1-30 From , joined Dec 1969, posts, RR:
Reply 11, posted (11 years 11 months 2 weeks 15 hours ago) and read 9608 times:

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

User currently offlineCV640 From United States of America, joined Aug 2000, 952 posts, RR: 5
Reply 12, posted (11 years 11 months 2 weeks 11 hours ago) and read 9590 times:

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.

User currently offlineBoeing nut From , joined Dec 1969, posts, RR:
Reply 13, posted (11 years 11 months 1 week 6 days 22 hours ago) and read 9516 times:

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!!!!

User currently offlineMD-90 From United States of America, joined Jan 2000, 8507 posts, RR: 12
Reply 14, posted (11 years 11 months 1 week 6 days 4 hours ago) and read 9439 times:

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).

User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 15, posted (11 years 11 months 1 week 6 days ago) and read 9447 times:

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-


User currently offlineMagicMan_841 From Canada, joined Jan 2002, 182 posts, RR: 0
Reply 16, posted (11 years 11 months 1 week 4 days 17 hours ago) and read 9372 times:

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

M@g!¢  Yeah sure


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