Where to find info on vibration testing on old aircraft? 1

[enginesrus]

They did wind tunnel tests in the 40's and 50's, and flutter testing, but did they ever do major vibration testing of the
older planes in those days?

 

[Sparweb]

Simple answer: Yes

Long answer:

https://ntrs.nasa.gov/

Are you specifically looking for body oscillations, such as the kinds tested by ground vibration tests? Look for NACA TN 3874 for an example.

http://www.sparweb.ca

 

[GregLocock]

No Highway in the Sky is from the right timeframe. Yes, fatigue testing of the whole a/c was a thing

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[rb1957]

is the question about vibration or fatigue or aero buffet ? Yes, I know vibration can cause fatigue, but when I hear "vibration" I think of DO-160 type questions.

perhaps the OP can refine his (non-gender specific) question …
aero buffet ?
fatigue ?
vibration (as it pertains to equipment) ?

does the OP have a specific question/installation/aircraft in mind ??

another day in paradise, or is paradise one day closer ?

 

[Andries]

You can also try the British "Reports and Memoranda" of the Aeronautical Research Council (ARC). They used to be downloadable from the Cranfield University Library.
The Royal Aircraft Establishment(RAE)also issued technical reports from the 1920s onward.

Andries

 

[WKTaylor]

In th early years of the Thorp T18, 2 Acft failed their stabilators very close to VNE... MUCH closer than design requirements. John Thorp became very concerned because flutter was suspected. As a result he ordered a VNE reduction of 30-mph IAS reduction in TAS... was 210-mph reset to 180-mph TAS.

He had an instrumented stabilator built... and he personally flew the high speed tests. He discovered that flutter on-set for the new stab began at roughly 230-mph IAS... and surprised him by getting much worse as he went slightly faster than intended (235-mph). During the next several dive tests, he noted that the flutter onset actually began at progressively lower IAS. He ceased the dive-testing when flutter onset began at ~225-mph IAS... for the brand new stab!!!

That was his 'eurica' moment... the 2 Acft that crashed were known to have been over-speeded a few times... and one was clocked by radar at roughly 220-mph when the pitch- over occured due loss of the stab.

The progressive reduction in flutter on-set airspeed scared him. The stab was obviously unstable too close to VNE and was obviously under strength. Excessive strain during the initial flutter on-set/rise... and subsequent events... was damaging the structure... and reducing the flutter on-set airspeed.

JT beefed-up the single tube spar with a tight fitting inner tube spar (~1/2 span, riveted together). He also did serious mass redistribution for the new structure.

Flight testing validated the new design flutter resistant above 250-mph (fastest he needed to 'proof').

The lesson JT passed-on (especially relevant to light weight sheet metal) was that significant strain into the plastic region at any time, will permanently affect the strain and vibration profile of the affected structure. Effectively, plastic strain exceedances 'unstiffened' the structure.

Regards, Wil Taylor

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