Speed Of Sound And Other Atmospheric Variables, Table of variation with altitude Options

[Omega892R09]

I hope this table based on that in Kermode, revised by Barnard & Philpott 1996, with conversions from metres/second to m.p.h. and knots is of use. If not delete post.

(IMG:http://lionels.orpheusweb.co.uk/Graphics/ATDataL.gif)

International Standard Atmosphere

based on US Standard Atmosphere 1962.

This post has been edited by Omega892R09: Aug 28 2008, 07:22 AM

[lunk]

Does breaking through the sound barrier happen at different speeds under different conditions?

Does mach 1 vary?

[Omega892R09]

Does breaking through the sound barrier happen at different speeds under different conditions?

Yes.

Does mach 1 vary?

Mach 1 is the speed of sound.

[lunk]

Thanks Omega,
I never knew that,
just figured so,
from your numbers.

cheers, lunk

[lunk]

Does this make it dangerous to travel around mach 1?
Is it better to be well over or under, rather than near this speed,
as it varies on conditions?

[albertchampion]

you know, supersonic flight is rather smooth. especially at high altitudes[above most weather].

i used to fly the concorde with some frequency[in fact, i was on the first flight departing the usa].

for the first hour or so, while transiting conus noise abatement zones, the plane flew subsonic. when it reached an area over the grand banks as i recall, it lit the afterburners. the two bulkheads had digital machmeters and the passengers could watch the increase in speed from mach .8 to 1+.

traveling from europe, the reheats bumped the concorde up to mach 1+ at some point offshore ireland.

in the early days, the aircraft flew very high. 58,000+. speed was governed by thermocouples in the wings' leading edge. the higher, the colder, the faster.

i recall that i was on the fastest crossing ever. we were streaking along at mach 1.68.

some complain about that bird. i have no complaints. even the upsets resulted in great stories. i can dine on those stories for years, i would like to think.

in the early days, i could leave houston in the morning and be in paris in time for a late dinner at my favorite 1 star.

i don't make that crossing so much these days. probably because supersonic travel has ended.

[Omega892R09]

Does this make it dangerous to travel around mach 1?

Yes for aircraft not designed for that speed regime.

Is it better to be well over or under,

It is certainly better being well over but only aircraft designed with that speed regime in mind will achieve it in one piece.

What becomes important is an aircaft's critical Mach Number and this can be different for any aircraft during various manouvers.

Look out for a copy of The Mechanics of Flight by A.C. Kermode:

http://www.amazon.co.uk/Mechanics-Flight-C...e/dp/0582237408

this one from MIT:

http://mitpress.mit.edu/catalog/item/defau...=2&tid=4921

may be interesting, I have not read this one and the statement:

The hero of the book is the Boeing 747, which Tennekes sees as the current pinnacle of human ingenuity in mastering the science of flight.

puts me off for either the author has never studied Concorde or suffers from extreme prejudice.

As for well over - once you get above about Mach 2.2 then kinetic heating must be accounted for and structural materials selected accordingly.

This is why Concorde is such a fascinating aircaft as the max Mach was kept down so as to be able to construct mostly with aluminium, albeit a special alloy of aluminium developed by Rolls Royce with aero engines - cylinders, pistons and supercharger centrifugal rotors - then GT compressors. Also with Concorde the fuel carried was used as a heat sink as well as a CofG & CofP change compensator.

When one considers the calculation tools available, or not, to the Concorde design teams then the achievment is even more impressive. IMHO

[Concorde discussion split by d to its own thread- the Concorde was one HELL of a piece of aeronautical engineering!]:

http://pilotsfor911truth.org/forum//index....showtopic=14609

[dMz]

Related posts are at:

Transonic wave drag- #343
http://pilotsfor911truth.org/forum//index....&p=10442823

also #311 on same UA175 thread
http://pilotsfor911truth.org/forum//index....&p=10366840

Drag- #9
http://pilotsfor911truth.org/forum//index....&p=10359321

"Mach"- #14
http://pilotsfor911truth.org/forum//index....&p=10396594

Turbofan thrust- #16
http://pilotsfor911truth.org/forum//index....&p=10462934

Air density and "Drag Ratios"- #18
http://pilotsfor911truth.org/forum//index....&p=10592382