Flight Test: The Avro Arrow and a Career in Aeronautical Engineering

The Arrow's Highest-Speed Flight​:

The published literature on the Arrow’s highest-speed flight has included some inaccurate and incomplete information, in part because pertinent data was initially classified and was withheld from the press. And until recently, the government-ordered destruction of Arrow documents prevented access to engineering flight test reports that could resolve discrepancies. However, the acquisition of the Ralph Waechter Fonds by LAC, and the inclusion of selected excerpts in Flight Test, has removed the latter problem. Some of the matters that are revealed by material in the Fonds include engine parameters during the highest-speed flight, the correct identification of those Mach numbers that were achieved in level flight vs. diving flight, and calibration data showing error bounds for Machmeter measurements. The latter information can explain small variations in published Mach number estimates.* The engine data shows that the rpm values for the high pressure compressors were at 99.8% for the port engine and 100% for the starboard engine, while both engines still had a little room to spare before reaching the recommended temperature limit. Statements made in some press reports and books that the high-speed run was carried out at less than full throttle have little significance since it is not unusual for an aircraft to reach an operational limit while still short of full throttle. The distinction between level flight and diving flight had to be correctly recorded in the flight test report because the rate of change of altitude was used in the report's aerodynamic drag calculations.   

Ralph Waechter's Avro Papers at
Library and Archives Canada

Ralph Waechter's Avro papers and other material from his career in aeronautical engineering were acquired by Library and Archives Canada (LAC) in 2016. ​ Click here  for further details.

Book Reviews

R. Isinger,CAHS Journal, Vol. 53/No.3 (2015) p. 84.
​T.F.J. Leversedge,
Airforce Magazine, Vol. 39/No. 3 (2016) p. 42.

Recent Publications {available via CAHS: click on title}

David Waechter, "The Highest Speed of the Avro Arrow: Reconciling Assorted Claims
CAHS Journal, Vol. 55/No.2 (2017) pp. 64-67. 

David Waechter, "Aeroballistics Range Tests of the Avro Arrow: A Lesser-known Investigation
CAHS Journal, Vol. 55/No.4 (2017) pp. 150-153.

David Waechter, "Jet Aircraft Operation: Early Work on Cruise Control and Computer Flight Planning"
CAHS Journal, Vol. 56/No.2 (2018) pp. 50-55.

Events in 2020
For a presentation for your organization in Southern Ontario (Toronto, Barrie, Kitchener, London and surrounding area),

contact David Waechter.

​Events in 2019
Nov 27: Presentation for Elmira Radio Club (Elmira, Ontario)​
May 22 - 25: Presentation for 
CAHS National Convention (Saint Anne de Bellevue, Quebec).​​


Events in 2018

April 18: Presentation for Kenneth Molson Lecture Series (Ottawa, ON).
  Follow this link for video: https://www.facebook.com/AvSpaceMuseum/videos/10155461876960418/?fref=mentions&__tn__=K-R
May 30 - June 3: Presentation for CAHS National Convention (Calgary, AB).

October 18: Presentation for ELO: Extended Learning Opportunities  (Erin, ON).
Events in 2017

January 12: Presentation for Retired Business and Professional Men's Club (Waterloo, ON).
February 4: Presentation for 
CAHS Toronto Chapter. Event photos at Gusair.com. 
May 18: Presentation for CAHS Montreal Chapter.
​June 8-11: Presentation for
CAHS National Convention(London, ON).

Events in 2016

Western Tour
September 15: Presentation for 
CAHS Calgary Chapter.
September 20: Presentation for CAHS Regina Chapter.

September 21: Presentation for University of Saskatchewan Aero Design Team. 

Ontario Events
June 25 & 26: Book Sales at the Quinte International Air Show.
April 28: Presentation for
 CAHS Ottawa Chapter.


​* Note: In different books on the Arrow it is common to see small discrepancies in the second decimal place of the Arrow’s highest achieved Mach number. However, a 1956 Technical Memorandum by researchers C.D. Brunn and W.H. Stillwell at the NACA High-Speed Flight Station stated that “an overall accuracy of 1 percent will be difficult to attain.” They later cited ±0.02 as the Mach number accuracy they could achieve near Mach 2. So debates over the second decimal place are not inherently resolvable because of the measurement limitations involved.