Supersonic 747
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Supersonic 747
If you got a couple of brave chap(ette)s and strapped them into a 747, got it up nice & high and then stuck the nose far down with max thrust and hung on ..... would it -
- Go supersonic.
- Be controllable.
- Hang together.
From a discussion on another forum.
- Go supersonic.
- Be controllable.
- Hang together.
From a discussion on another forum.
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i believe on the flight tests during dives well into the mach .9s were achieved. Also there was a major incident with a far east (china?) 747 yrs ago where they made a balls up of an engine flame out on the pacific.....between the farting around and doing nothing the aircraft ended up in a spiral dive and they reckon some of the control surfaces went supersonic.
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One DC-8-4X did reach Mach 1,012 already in 1960-s and recovered. A shallow dive as a part of deliberate flight testing.
They also had water ballast tanks AND pumps installed in the cabin to resist Mach tuck.
Can any subsonic plane recover from a Mach 1,000 dive without ballast pumps?
Which ones? Is 747 among them?
They also had water ballast tanks AND pumps installed in the cabin to resist Mach tuck.
Can any subsonic plane recover from a Mach 1,000 dive without ballast pumps?
Which ones? Is 747 among them?
Thread Starter
Boeing tested the prototype up to M 0.991. I can't find anything that confirms for sure that the China Airlines SP went supersonic, in fact it seems more likely that it didn't.
The other thing that was talked about is that the engines would likely flameout.
The other thing that was talked about is that the engines would likely flameout.
To the best of my recall, the B747 is not fitted with a Mach Trimmer (cf the B707) therefore if the certifying authorities deemed it unnecessary then I presume that the handling at high mach nos` is benign. Remember also that demonstrated Vmd is quite a bit higher than Vne. Never was a problem demonstrating it in the sim on conversions however fidelity may be an issue here.
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Link to video:
http://www.liveleak.com/view?i=e9f_1180909211
http://www.liveleak.com/view?i=e9f_1180909211
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mmm.. if one was to attach some trent 900 engines instead of the Rolls 747 engines (provided they'd fit properly), add structural strength AND install some disposable, but strong rockets on the fuselage, could be a fun experiment!
(don't try this at home kids)
(don't try this at home kids)
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Why would any pilot want to take an aircraft beyond it's defined envelope?
During acceptence flights, I've taken the Classic to Vmo/Mmo, 392 KIAS/0.92 M. Between FL 26 and 29 in level flight advance to maximum rated thrust and accellerate. This usually produces something about 380KIAS. A slight push over will result in the 392/.92 rather quickly, with the over speed warning within 3 kts and .01 M. And thats what we want to see. Every once and a while you get a very slight burble or low rumbel as the air starts to go supersonic somewhere above the flightdeck.
Generally the intake airspeed of a jet engine does not like supersonic airflow. I would hate to see the dampage on the N1 rotors after any lengthy exposure to this rate of airflow and the boundary separation that would be occurring. As the airflow entered the N2 the engine would likely fail.
Want to go supersonic in a 747, go fly down wind in the jet stream, as previouly suggested.
During acceptence flights, I've taken the Classic to Vmo/Mmo, 392 KIAS/0.92 M. Between FL 26 and 29 in level flight advance to maximum rated thrust and accellerate. This usually produces something about 380KIAS. A slight push over will result in the 392/.92 rather quickly, with the over speed warning within 3 kts and .01 M. And thats what we want to see. Every once and a while you get a very slight burble or low rumbel as the air starts to go supersonic somewhere above the flightdeck.
Generally the intake airspeed of a jet engine does not like supersonic airflow. I would hate to see the dampage on the N1 rotors after any lengthy exposure to this rate of airflow and the boundary separation that would be occurring. As the airflow entered the N2 the engine would likely fail.
Want to go supersonic in a 747, go fly down wind in the jet stream, as previouly suggested.
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I have been supersonic a couple of times in a/c that had the airframe capability but not the thrust (no re-heat). I takes a lot of oomph to get throught the barrier. In both of the types the technique was to climb to fl450 then with full power roll inverted, pull the nose to 45 degrees down then roll right way up again. You were supersonic just long enough to say "wow hasn't it gone quiet and smooth" before pulling like hell to avoid making a bid hole and a nasty mess. G capability is much reduced when supersonic due reduced lift. Bearing this in mind I think the chances of getting a 747 supersonic and surviving it are pretty slim.
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The Mythbusters will probably come up with the answer!!
Incidently if you ever achieve Mach tuck with the stick hard back and the pitch down continues, let it go under and roll out the other side - better than making a big hole in the ground.
Incidently if you ever achieve Mach tuck with the stick hard back and the pitch down continues, let it go under and roll out the other side - better than making a big hole in the ground.
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C of P?
Not that I've ever flown the thing but?
Surely the thing would "take a dive" Cof P Where?( considering of course it had the thrust to push it through/displace the bow wave).
H/Snort
Surely the thing would "take a dive" Cof P Where?( considering of course it had the thrust to push it through/displace the bow wave).
H/Snort
Why would any pilot want to take an aircraft beyond it's defined envelope?
Want to go supersonic in a 747, go fly down wind in the jet stream, as previouly suggested.
Want to go supersonic in a 747, go fly down wind in the jet stream, as previouly suggested.
It's an interesting discussion though. I seem to recall it got a mention in the book, 'Handling The Big Jets'.
From what you posted Mustangsally, you're the only one here who has nudged the envelope!
Thread Starter
From what you posted Mustangsally, you're the only one here who has nudged the envelope!
The aeroplane handled just fine at those speeds.
The stabiliser trim should have more than enough authority to counter mach tuck - there's usually only about 4 units set in the cruise, with 9.0 available.