Two rare sightings

[chrispbits]

We often have Yaks as well as Apaches over ours. The local airfield has about 6 Yaks. Fortunately they're all well behaved - no reported instances of Yak droppings in the neighbourhood.

[Motormouse]

I once took a flight in the rear cockpit of an SNJ-5...the US Navy version of the T6. Much to my disappointment I couldn't hear the propeller growl from inside the aircraft. Still had a lot of fun. The pilot let me take the controls for part of the flight.

Brian

I got to fly one from the front seat, the only time we made the prop snarl was on the break to land...

Ttfn

Pete

[Airspeed]

No camera handy for either of these

I know what you mean. Some years ago, I was at a very small airfield in the UK. Basically, I was the only one watching. Nothing happened for ages and then to my surprise, a UFO landed. My flabber was further gasted, when a hatch opened and out stepped Bigfoot, the Loch Ness Monster and Elvis. And guess what? My camera wouldn't work!

Kevin

Kevin,
Sorry this took some time to get past the Alien jamming rays.
Just wanted to say that it's the feedback from those huge anal probes that stops the cameras from working, or at least makes the pictures fuzzy.

[Dev One]

With ungeared engines, you only need a prop of about 8 feet 5 inches diameter to start getting into the transonic region at high rpm. It became a notorious problem with aircraft such as the ATP which, like the Harvard, made a noise like ripping calico !

Its not just the rotation speed, your forward speed adds to it to go supersonic - When the Thruxton Jackeroos were racing at Coventry one year, a pair of them had larger dia fine pitch props & they were noisy - not as bad as the Harvard though.
Keith

[dfarrow]

CS , agree on the Harvard tips going supersonic . The company one at Compton Abbas if wanting to attract attention certainly does on most joy ride flights . If solo , she can be airborne with lower prop RPM , and thus quieter .
Had 4 very happy years flying ATPs with Highland Division based in GLA , and this is the first I've heard of props tips going supersonic . Every day a learning day .
They are 16 feet across 6 blade plastic , and if memory serves Dowty's from Gloucester way .
Prop RPM at one point in flight [ forgotten which ] was 1000 or a brain cell says 1050 .. Always understood they did not run fast to avoid tips in sonic range with that hugh dia.
Heard many taxi out /in from the ramp awaiting our a/c if late ...Advanced Technical Problem and always thought it a quiet-ish sound , especially after 2 Darts on a Budgie or 4 on a Viscount . Have heard Vanguards/Merchantmen but forgotten the sound.

rgds dave f.

[cstorey]

Dave f : interesting to hear from someone who actually flew the ATP . When I was Liverpool based we had the Manx ATP around daily, and later IIRC one that went to the ill-fated Emerald . If we were standing side on to the props during startup we certainly got the ripping calico as the speed rose,and/or the props were exercised, which perhaps wrongly we put down to supersonic tips . The props were of course geared in that case, and I do wonder whether the multi-bladed effect ( were the 6 blades curved scimitar like blades ?) - had something to do with it because I imagine that at certain pitches the leading edge of the succeeding blade was running straight into turbulence from the trailing edge of the preceding blade , particularly when the aeroplane was stationary, which was the only time we noticed it

[dfarrow]

CS , Amazing how when a subject is discussed with back and forth , the memory cells from 30 yrs ago are reactivated . Don’t think that’s in aircrew human factors training .
You’ve brought it back to life .. ATPs were started [ I think ] with props in feather position , when core running , the prop was unfeathered and brought up to speed . Similar on shutdown , after a cooling cycle prop lever to feather and cut off . In both those actions there was a definitive noise change as pitch and rpm changed . Don’t know if that’s prop interference , Doppler , or just teh properties of disturbed air . You’d need a PHD in prop design to know ..
Anyone from Dowtys here ? Don't really think it was supersonic as a/c marketed as Quiet ..Indeed Manx had a G-UIET

There was a torque reaction as well , the a/c shuffled a little as props went up or down on start and shutdown . We thought it poor design that the AC generators were geared to the Props , not the Engine , as in the ATR 42/72 . Thus ATRs could use an engine in ‘Hotel’ mode as an APU , with prop stopped and tethered . Very useful , kept the a/c independent of ground services ; whereas we needed a GPU/start cart . Although battery starts were easier than the ‘Budgie’ .
Might even have contributed to the fact of having a different X-wind limit for wind from Port or Starboard side .

The props were not Scimitar shaped , plastic , not quite a full paddle as in Herk’s T56s . plenty of area when put to fully fine for t/o , and final app . Very useful at altitude , could even do a 1 in 1000 app , if gear down , <140kts full flap , throtts closed and props to ‘Max’ [rpm] ..that’s 10 nm out from 10,000’.
Link below has several shots of ATP props in various states .

https://www.google.co.uk/search?q=BaE+A ... kBCuSj3fZM

Replying to this got me finding this , production /history list .

https://rzjets.net/aircraft/?page=1&typeid=34

rgds dave f.

[Vc Ten]

At our tech school we had a Fairey Gannet, which our training instructors would "exercise" every month or so. Cartridge start, and once wound up, the noise was phenomenal. You could see lines through the air from the prop tips (and there was a few of them) . I think the run ups were eventually stopped due to the disturbance to the non aeronautical students.
The aircraft was later moved, after my time there, to the front of the college as a gate guard.
Don't know what happened to her after that.
There was also a Supermarine Swift which used to be able to be started up. Used a mono fuel as a starting agent, Isopropyl nitrate?? We could never go near the stuff. Bit volatile apparently
Dale

[cstorey]

Dave f and Dale : fascinating stuff - it was plainly the pitch change during or perhaps more accurately after startup that caused the ATP noise rather than supersonic tips, but the noise was very distinctive. Also fascinating about the Gannet - I did have a lovely colleague called Clare Pollard who had been on Gannets ( can you imagine a man with a bushy beard called Clare in RN??!!) - and IIRC the rear prop on the Gannet was started from the propwash of the front engine, so it was inevitably a noisy business

I have always wondered exactly what it is that gives some a/c their distinctive noise - the latest prize goes to the A400M that I can instantly recognise at 25,000 feet even when I am indoors

[dfarrow]

CS , like you I wonder .
BAC 111s on start the Speys sound like a sewing machine on wind up .
Tristars Rb 211 22cs like a rumbling diesel starting .
The Darts whine , garrett APUs whistled hi pitch , I guess due to hi RPMs [ C40,000 on similar Artoustes and Paloustes ].

A400s sometimes are around 3t' herabouts , deffo not stealth . And once or twice a pair of Ospreys ..weird unless living in E 'Angular .

rgds dave f.