Aircraft Quiz No. 124

[Doug Robertson]

Name the aerodynamic issue problems that accompany supersonic and hypersonic flight. Divide/name your answers between the two flight speed attributes. This may be one of my most difficult Aircraft Quizzes.

[moxy]

Could write a book on this!

Supersonic

When the critical Mach number (when the airflow over any part of the aeroplane reaches but does not exceed Mach 1) is exceeded by 5 to 10 percent, compressibility effects begin. Drag rises sharply, with buffet, trim and stability changes. The control surfaces are less effective.

Hypersonic - Over Mach 5

Extreme temperatures caused by friction, air resistance together with shockwaves, requiring very special materials in aircraft manufacture. Difficult maneuverbility.

Regards
Rob

[Doug Robertson]

Rob, I salute you, you got it!

When an aircraft reaches the speed of sound-around 760 mph, less at higher altitude, the particles of air cannot flow around the aircraft-they are compressed into a barrier of air. Prop aircraft and early jets were not powerful enough to penetrate the "sound barrier".

It gets more difficult-as the speed of sound varies by altitude, 760 mph at sea level would be around 100 mph more above the speed of sound at 35,000 feet, for example. This required a new system of measurement-the basic unit- the Mach which was named after Dr. Ernst Mach of Austria. He early on investigated ballistics, with Mach 1 being the speed of sound-independent of altitude. Mach 2 being twice the speed of sound, etc. Speeds of sound from Mach 2 twice the speed of sound were independent of altitude. Any speed of Mach 1 through Mach 4 was called supersonic; hypersonic referred to speeds at Mach 5 and above.

Again, I thank you! and I would like to read your book!

[moxy]

Fascinating subject Doug but the book will have to wait! Concentrating on documenting my dad's service in the Royal Air Force 1934 -1946.

[Malcolm Clarke]

You have the right priority Rob. My late father saw service in the RFC from 1914 to 1919 by which time it had become the RAF.
He served as a rigger behind the lines in France helping to keep the "string bags" in the air.
As with all who served in WW1 he was placed in the Reserves and was called up again in 1939 to serve as a Flight Sergeant in the RAF with most time spent in Iceland looking after those who flew the Atlantic.
I have his official records thanks to the War Office. Good luck with the project.
Malcolm.

[moxy]

Thanks Malcolm

We have to record the lives and the memories passed on to us by our parents and grandparents, particularly those who served our country in the armed services. If we don't they will be lost forever and can not be passed on down the line.

Your late father sounds like he certainly did his bit and should be remembered always for his service to our country.

My late dad started in 1934 at he Electrical and Wireless School, Halton and was then posted to 101 Bomber Sqdn, Bicester on Boulton Paul Overstrands as a Wireless Operator/Wireless Electrical Mech. Then to 715 Catapult Sqdn, with about five other RAF bods on HMS Kent, China Station, operating the Walrus on fleet spotting etc. After being injured when the Kent was attacked he spent a while in the RN hospital Haslar at Gosport before going to No 1 signals school at Cranwell, being commissioned after Officers School, Cosford and ending up with 178 Sqdn, Mediterranean Allied Air Force in Foggia, Italy, on Halifaxes and Liberators.