shock stall

English

WOTD – 13 February 2020

Etymology

The noun is derived from shock + stall (“loss of lift due to an airfoil’s critical angle of attack being exceeded”).^[1] The verb is derived from the noun.

Pronunciation

(Received Pronunciation) IPA^(key): /ˈʃɒk ˌstɔːl/
Audio (Southern England): (file)
(General American) IPA^(key): /ˈʃɑk ˌstɔl/

Noun

shock stall (plural shock stalls)

(aviation) A stall (“sudden loss of lift”) caused when the airflow over an aircraft's wings is disturbed by shock waves that occurs at a specific Mach number when the aircraft is accelerating to transonic speeds.
- 1944 April 27, Peter Caygill, quoting Tony Martindale, “Problems with Compressibility”, in Sound Barrier: The Rocky Road to MACH 1.0+, Barnsley, South Yorkshire: Pen & Sword Aviation, Pen & Sword Books, published 2006, →ISBN, page 41:
  When I was down to 32,000 feet the altimeter was spinning merrily and the dive was very steep and I was pulling back on the stick in the usual way due to the change of trim at the shock stall.
- 1947 August, Oliver Stewart, “Breaking the World’s Speed Record”, in Max Karant, editor, Flying, volume 41, number 2, Chicago, Ill.: Ziff-Davis Publishing Company, →ISSN, →OCLC, page 60, column 1:
  His [Group Captain Hugh Joseph Wilson's] flights revealed at least two things: the effectiveness of turbojets used for the first time in international record breaking, and he came sufficiently close to the speed of sound to experience the effects of a partial shock stall. [...] It was noticed that changes in the air flow occur when the speed approaches the speed of sound—or, in other words, the speed at which waves propagate themselves in air—and that these changes could lead to a partial or complete shock stall.
- 1949 December, “Jetterbugs Made: Not Born to the Trade”, in Arthur L. Schoeni, editor, Naval Aviation News, number 332, Washington, D.C.: Chief of Naval Operations and Bureau of Aeronautics, →ISSN, →OCLC, page 2, column 2:
  A new realm in aerodynamics is entered, with sound and shock waves, Mach number and compressibility making their appearance. Life saving dope is disseminated [during ground training] on the warning signals and recognition of shock stalls and measures in recovering from them.
- 1956, A. S. Hartshorn, L. F. Nicholson, The Aerodynamics of the Cooling of Aircraft Reciprocating Engines (Reports and Memoranda; 2498), London: Her Majesty’s Stationery Office, →OCLC, page 37:
  Direct evidence is meagre, but suggests that local shockstalls of this type do not generally imply a severe increase of drag, but may occasionally set up buffeting effects.
- 1968, Lars E. Ericsson, J. Peter Reding, Unsteady Airfoil Stall and Stall Flutter (NASA Contractor Report; NASA/CR-111906), Washington, D.C.: National Aeronautics and Space Administration, →OCLC, page 34:
  Compressibility effects are not found to change the dynamic stall characteristics in principle until the Mach number gets high enough to cause shock-stall rather than leading edge stall.
- 2001, Paola Cinnella, “Numerical Study of Transonic Shock/Boundary Layer Interactions on an Oscillating Airfoil Using a Third-order Scheme and Nonlinear Turbulence Models”, in Nobuyuki Satofuka, editor, Computational Fluid Dynamics 2000: Proceedings of the First International Conference on Computational Fluid Dynamics, ICCFD, Kyoto, Japan, 10–14 July 2000, Berlin, Heidelberg: Springer-Verlag, →DOI, →ISBN, part V (Compressible Flows), section 1 (Introduction), page 157:
  In the present work, the shock stall of an oscillating NACA64A010 airfoil for which detailed experimental data are available is studied.
- 2010, Tony Doyle, “To Valley on the Gnat”, in Flying at the Edge: 20 Years of Front-line and Display Flying in the Cold War Era, Barnsley, South Yorkshire: Pen & Sword Aviation, Pen & Sword Books, →ISBN, part 2 (The Crest of the Wave), page 159:
  Anyone on the instructor's course should be experienced enough to handle the odd shock stall, which by definition was only going to happen at height where there was plenty of room to sort things out.

Alternative forms

shockstall, shock-stall

Translations

sudden loss of lift that occurs at a specific Mach number

Finnish: yliäänisakkaus

Verb

shock stall (third-person singular simple present shock stalls, present participle shock stalling, simple past and past participle shock stalled)

(intransitive, aviation) Of an aircraft or a component of it: to undergo a shock stall.
- 1947, S. Kirkby, A[braham] Robinson, Interference on a Wing due to a Body at Supersonic Speeds (Aeronautical Research Council Reports and Memoranda; no. 2500), London: Her Majesty's Stationery Office, published 1952, →OCLC, page 23:
  The tailplane usually becomes more effective as a stabiliser at high Mach numbers because there are decreases of wing lift-curve slope and rate of change of downwash with mean lift coefficient. The latter effect is mainly due to the wing-root shock stalling at a lower Mach number than the rest of the wing.
- 1947 January, The Journal of the Royal Aeronautical Society, volume 51, part 1, London: Royal Aeronautical Society, →ISSN, →OCLC, page 130, column 1:
  [A] loss of downwash due to the main wing shock stalling would result in an undesirable diving tendency.
- 1948 August, John Stack, W. F. Lindsey, “Summary”, in Characteristics of Low-aspect-ratio Wings at Supercritical Mach Numbers (National Advisory Committee for Aeronautics Technical Note; no. 1665), Washington, D.C.: National Advisory Committee for Aeronautics, →OCLC, page 1:
  The separation of the flow over wings precipitated by the compression shock that forms as speeds are increased into the supercritical Mach number range has imposed serious difficulties in the improvement of aircraft performance. These difficulties arise principally as a consequence of the rapid drag rise and the loss of lift that causes serious stability changes when the wing shock-stalls.
- 1949 June, R. G. Naugle, “Are Jet Fighters Overrated?”, in William B[ernard] Ziff [Sr.], editor, Flying, volume 44, number 6, Chicago, Ill.: Ziff-Davis Publishing Company, →ISSN, →OCLC, page 68, column 1:
  In fact, in this case, after stalling in the normal manner, he would probably have fallen off in a dive and in doing so, increase his speed until he shock[-]stalled before effecting recovery.
- 1949 October, K. W. Todd, An Experimental Study of Three-dimensional High-speed Air Conditions in a Cascade of Axial-flow Compressor Blades (Aeronautical Research Council Reports and Memoranda; no. 2792)‎^[1], London: Her Majesty's Stationery Office, published 1954, →OCLC, archived from the original on 3 October 2015, page 1:
  As a result of these tests it was shown that at the design incidence the conventional cascade shock stalled at some 75 per cent of the critical inlet velocity.
- 1951, staff of the RAE [Royal Aircraft Establishment] High Speed Wind Tunnel, High Speed Wind Tunnel Tests on Models of Two Jet-propelled Fighters (Meteor and Vampire) (Aeronautical Research Council Reports and Memoranda; no. 2504), London: Her Majesty's Stationery Office, →OCLC, page 35:
  When the wing shock stalls, the lift gradient $a$ falls and, if no shock stalling occurs on the tail plane, the term ${\frac {a_{1}{\bar {V}}}{a}}$ increases, thus increasing the tail plane contribution to stability.

Alternative forms

shock-stall

Derived terms

shock-stalled (adjective)
shock stalling (noun)

Translations

to undergo a shock stall

References

^ “shock stall, n.” under “shock, n.³”, in OED Online ⁠, Oxford: Oxford University Press, 1914; “shock stall, n.”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

English

Etymology

Pronunciation

Noun

Alternative forms

Translations

Verb

Alternative forms

Derived terms

Translations

References

Further reading