How STRONG is a 757 ?
Thread Starter
Joined: Dec 1999
Posts: 0
Likes: 1
From: UK
How STRONG is a 757 ?
What would it be like at 500kts indicated,low level in a B757 ?
And being around 150kts above Vne,what are the chances of breaking up ? (Assuming you're being gentle on the G - or not?)
What do the boeing test pilots do as a matter of course ? (Indicated)
What is the fastest a Boeing has ever flown and survived ?
And being around 150kts above Vne,what are the chances of breaking up ? (Assuming you're being gentle on the G - or not?)
What do the boeing test pilots do as a matter of course ? (Indicated)
What is the fastest a Boeing has ever flown and survived ?
Joined: Jun 2001
Posts: 2,627
Likes: 2
From: UTC +8
Joined: Feb 2002
Posts: 417
Likes: 20
From: D(Emona)
Let's calculate dynamic pressure for max design speed and 500 kts indicated at sea level in standard conditions.
At 350 KIAS it is 3.11 psi
At 500 KIAS it is 6.34 psi
; which is more than a double
I would say this is above elastic modulus ((design x 1,5) x 1,15 if I remember correctly) for a structure of this type and permanent damage would occur.
At 350 KIAS it is 3.11 psi
At 500 KIAS it is 6.34 psi
; which is more than a double
I would say this is above elastic modulus ((design x 1,5) x 1,15 if I remember correctly) for a structure of this type and permanent damage would occur.
Thread Starter
Joined: Dec 1999
Posts: 0
Likes: 1
From: UK
Clandestino
You're right ,I was reading about 9/11.
I also flew the 757/767 and got to thinking what it would be like at 500kts.
Have you anything useful to say ?
Dufo
Thanks. It might be permanently out of service but would a critical bit break off ? I think it would be noisy
You're right ,I was reading about 9/11.
I also flew the 757/767 and got to thinking what it would be like at 500kts.
Have you anything useful to say ?
Dufo
Thanks. It might be permanently out of service but would a critical bit break off ? I think it would be noisy
Last edited by Stan Woolley; 15th October 2013 at 09:24.
Joined: Oct 2007
Posts: 1,003
Likes: 16
From: Here
DC8 laundry moment
Glueball mentioned
Thanks, well worth a read.
It seems to have been not entirely without incident.
Supersonic flight was achieved in a 20 degree dive.
"however the initial application of full up elevator did not appear to produce any noticeable change in the load factor"
They recovered by using the pitch trim. All moving tail trim? Reading between the lines I sort of guess that this was expected really - but still.
"A severe rudder pedal "buzz" was apparent ... from the oscillograph records ... The rudder control tab maximum movement was recorded as 21.3 degrees double amplitude, at a frequency of approximately 28 CPS."
Not sure what "double amplitude" means but it is still a large movement.
The DC-8 Supersonic Flight
It seems to have been not entirely without incident.
Supersonic flight was achieved in a 20 degree dive.
"however the initial application of full up elevator did not appear to produce any noticeable change in the load factor"
They recovered by using the pitch trim. All moving tail trim? Reading between the lines I sort of guess that this was expected really - but still.
"A severe rudder pedal "buzz" was apparent ... from the oscillograph records ... The rudder control tab maximum movement was recorded as 21.3 degrees double amplitude, at a frequency of approximately 28 CPS."
Not sure what "double amplitude" means but it is still a large movement.
Joined: Feb 2005
Aviation Qualifications: ATPL
Posts: 1,427
Likes: 5
From: Correr es mi destino por no llevar papel
Have you anything useful to say ?
2. this was discussed many times at length here by folks who know a lot about certification testing. Conclusion was it was quite possible for 757 to reach 500 kt practically undamaged. That didn't deter conspiracy theorists, though and it would be even worse if some Buck Rogers wannabe imagines that means he can go through Vmo without consequences.
3. you might find more receptive audience at sites with black background and banners screaming about government keeping us in dark.
I would say this is above elastic modulus ((design x 1,5) x 1,15 if I remember correctly) for a structure of this type and permanent damage would occur.
Joined: Jul 2002
Posts: 3,093
Likes: 0
From: UK
Added to which, a 757 on a low pass at full chat doesn't sound like you might expect it to - those RB211s make some serious noise!
She acquired the nickname "Mighty" because she was considerably over-powered compared to other types - those engines were originally designed for the much larger and heavier L-1011 TriStar. The RNZAF (see video) have become well-known for displaying their 757s as handling almost like fighters.
She acquired the nickname "Mighty" because she was considerably over-powered compared to other types - those engines were originally designed for the much larger and heavier L-1011 TriStar. The RNZAF (see video) have become well-known for displaying their 757s as handling almost like fighters.
Last edited by DozyWannabe; 15th October 2013 at 13:47.
Thread Starter
Joined: Dec 1999
Posts: 0
Likes: 1
From: UK
Actually I was thinking about the wind noise in the cockpit when I said it would be loud.
What a great sound & low pass !
It makes a distinctive sound when you press TOGA on take -off. Can't remember similar - maybe the A320 ? Can't imagine that wheezy old trout making the same noise as the Mighty 757 ! ( No offence )
What a great sound & low pass !
It makes a distinctive sound when you press TOGA on take -off. Can't remember similar - maybe the A320 ? Can't imagine that wheezy old trout making the same noise as the Mighty 757 ! ( No offence )
Joined: Jul 2002
Posts: 3,093
Likes: 0
From: UK
Oh, the A320 can be spectacular in her own way, but one thing she isn't is overpowered - she was designed as a pure short-haul type, whereas the B757 was designed for medium-haul, and with the coming of ETOPS has even been used as a long-haul type in her later years. The 757 is definitely one of my favourites of the B types, but the things that made her mighty also made her less economical to run in most use cases as time passed.
Joined: May 2002
Posts: 942
Likes: 0
From: dubai
Ah the DC 8. They don't make planes like that anymore! Nor the 707 or VC10 for that matter.
As for going supersonic, they were probably lucky to have got away with it. Due to the rapid and large C of P change, a fully flying tail plane is necessary. Using pitch trim was the next best thing, albeit slow, for longitudinal control.
As for going supersonic, they were probably lucky to have got away with it. Due to the rapid and large C of P change, a fully flying tail plane is necessary. Using pitch trim was the next best thing, albeit slow, for longitudinal control.
Joined: Jul 2002
Posts: 3,093
Likes: 0
From: UK
Pictures: Airbus adopts Vickers VC10 landing gear concept for A350 XWB
Anyways - sorry - back on-topic!
Joined: Jan 2009
Posts: 1,415
Likes: 432
From: Cab of a Freight Train
Didn't that China Airlines 747SP get close to, or exceed, Mach 1 during its upset, they just didn't have the DFDR data to prove it?
Iv'e got a book somewhere that claims they probably exceeded the speed of sound but the flight recorder wasn't working during the periods it would have - convenient?
Iv'e got a book somewhere that claims they probably exceeded the speed of sound but the flight recorder wasn't working during the periods it would have - convenient?