Flying - 1953 Style

[red750]

This could also appear in Aviation Videos. This video came up after the story about the drunk passenger attacking the pilot over a delayed flight. It is a film describing flight in a Super Constellation, showing passengers what goes on in the cockpit. One interesting sequence shows them feathering first engine 1, then 2, then 3, and flying on engine 4 only. It also shows a Lockheed Starfire to demonstrate jets, and talks about jet transports in the future.

 

https://www.youtube.com/watch?v=eVE1AzwJLTE

 

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[sixtiesrelic]

As usual Pete, you find the interesting ones.

 

Bit scary seeing them land just past the threshold rather than today's 1000 feet in to give a safety buffer on a bit of down draught near the end of the runway.

 

 

[siznaudin]

And how about smoking a cigarette in the cockpit ... ah yes, bring back the 50's!

 

Flying on #4 alone must have required some rudder correction too!

 

As an aside, I was surprised to see the Starfire shown exceeding Mach 1 - yes I understand it was in a dive, but I'm surprised nonetheless.

 

Any comments?

 

 

[mnewbery]

Here's one: They still sold laudanum over the counter in 1953 too. We've come a long way since then and I am not sure the Super Constellation would have survived as a concept without serious regulation of the market. No surprise then that the last (L-1649) Star Liner was built just before de-regulation (in Australia) had its effect in the 1980's.

 

America's turn at de-regulation started in 1978 according to wikipedia.

 

 

[willedoo]

As an aside, I was surprised to see the Starfire shown exceeding Mach 1 - yes I understand it was in a dive, but I'm surprised nonetheless.

Any comments?

As far as I know, there were a few subsonic jets that achieved supersonic flight in a dive.

 

It would be interesting to read their stories and find out what went into the test flights leading up to the actual event.

 

I would suppose a lot would depend on the individual design as to whether flow separation around the control surfaces would present a big problem. For a subsonic aircraft to obtain that speed in a dive, the two biggest problems would be loss of elevator control and flow separation at the intakes causing engine problems.

 

But I guess in a dive a lot of the problems encountered in level flight would be reduced somewhat. Normally a subsonic intake is maximised for anything up to high subsonic speeds. In level flight at transonic to supersonic speeds, the intake shock wave would tend to detach forward as a bow shock and reduce thrust due to the increased drag and pressure loss. Perhaps the momentum of a dive negates that factor allowing the speed to be attained. Also, I wonder if the angle of attack of the dive tends to carry away the disturbed air around the elevators, allowing better control than what would be possible in level flight.

 

Starting the dive at 45,000' like that should have one advantage as well, the speed of sound would be about 20% less than at sea level. I'd guess most subsonic jet fighters in those early times would have attempted it ; how many achieved it would be another thing.

 

Cheers, Willie

 

 

[siznaudin]

Gawd knows if this link will work, but as well, here's a somewhat fuzzy clip from it (Shooting Star pilot's manual). Further comments are invited from anyone who has an understanding of just exactly what "critical mach number" is.

 

http://books.google.com.au/books?id=zxsAFkQD7YcC&pg=PA37-IA2&lpg=PA37-IA2&dq="shooting star" "critical mach number"&source=bl&ots=XKdHhT4d1e&sig=E06uJlgtbg30IHBWA6wF6MpohpI&hl=en&sa=X&ei=VL3TUd2GL4fNkwWQs4DgDg&ved=0CEAQ6AEwAw#v=onepage&q="shooting star" "critical mach number"&f=false

 

[ATTACH=full]1841[/ATTACH]

 

Does this then mean it could not reach/exceed Mach1 ?

 

Stop Press: from Wiki ... "Although unknown at the time, compressibility was the cause of the phenomenon known as the sound barrier. Subsonic aircraft such as the Supermarine Spitfire, BF 109, P-51 Mustang, Gloster Meteor, He 162, P-80 have relatively thick, unswept wings and are incapable of reaching Mach 1.0."

 

So what do we make of that, in relation to the Youtube clip, I ask.

 

[ATTACH]18427[/ATTACH]

 

[ATTACH]18437[/ATTACH]

 

 

 

 

[mnewbery]

Incapable of a) going trans sonic while straight and level b) staying in control while transitioning to supersonic

 

It came down to where the shock wave and flow separation occurred. If it occurred on the control surfaces such as the elevator or ailerons, bye bye. Mach tuck would turn the air frame to confetti. The control surfaces would work like a swim fin in a broken wave at the beach. Badly.

 

The fat winged P38 had a critical Mach of 0.69. This is because the supersonic flow over the top of the wing occurred at a relatively low airspeed.

 

Fat wing=not supersonic

 

Not so fat wing (Spitfire) ... Maybe

 

 

[willedoo]

. Further comments are invited from anyone who has an understanding of just exactly what "critical mach number" is.

Well, don't quote me on this; it's just my possibly incorrect understanding of it.

 

The speed of sound varies depending on altitude and is largely influenced by absolute temperature. Temperature decreases with altitude causing the speed of sound to decrease as well.

 

At subsonic speeds the compressibility effects which effect the aerodynamic performance of the aircraft's surfaces is neglible.

 

Flight speed alone is not a reliable indicator of compressibility effects because the behaviour of air depends on altitude. However, referenced to the speed of sound, it provides a reliable indicator of the effects of altitude on the aircraft's aerodynamics. This is known as the Mach Number; mathematically it's airflow velocity over speed of sound.

 

Transonic flight is the range between subsonic and supersonic, the point from which the first portion of airflow over the surfaces reaches the speed of sound, up until the entire airfllow over the surfaces is at the speed of sound.

 

Critical Mach is the lowest speed at which some airflow reaches the speed of sound.This is the start of the transonic transition period, where all the fun and wierd stuff happens. The aeroplane is travelling slower than some of the airflow over it's surfaces, causing drag inducing shock waves which prevent supersonic speeds in level flight. Later designs with thinner, swept wings etc. reduced the amount of shock waves on the surfaces.

 

The other downside from Critical Mach onwards until the more stable supersonic flight is the adverse affects on control surfaces, lift, and inadvertant pitch up or down, caused by the shock waves increasing in size & changing direction.

 

I don't know much about the Starfire, but I'd be guessing it would be like the Sabre & the later model Mig-15/17's where the airframe design was capable of supersonic flight, but unable to achieve it in level flight due to lack of engine thrust. This comes back to earlier comments about the engine intake shock wave detaching forward causing drag. Hence the later designs of axially translated shock cones and variable ramps.

 

Probably can't add much more without knowing a bit more about the Starfire's design.

 

Just as a side note, the very early MiG-15's had a design problem which made them behave very badly at high subsonic/ pre-transonic speed. In typical Russian fashion, they wired it up to deploy the speed brakes whenever it reached a speed just below that. That way they kept flying them operationally for quite a long time until the design flaw was fixed.

 

Cheers, Willie.