About to stall.................?

[tarantonight]

Interesting footage. Didn't do that well at physics in my youth, but I do know that heavy things don't stay up all that long.

What do you boys think of the attached?

Jumbo Jet Hovers In the Sky on MSN Video (http://video.uk.msn.com/watch/video/jumbo-jet-hovers-in-the-sky/1j47j97iy)

[Albert Driver]

I once saw a hangar roof hover in the sky.....


It was still obeying the laws of physics.
.

[longer ron]

Lovely day for an airshow LOL
FFFFairly windy what !!:rolleyes:

[Union Jack]

What do you boys think of the attached?

Well, I this "boy" thinks that you should have a look at the two pages of relevant posts in Spotters' Corner!:E

http://www.pprune.org/spectators-balcony-spotters-corner/468796-cathy-a330-hover-mid-air-air-show.html

Jack

[ORAC]

Pah! Modern FBW stuff.

Had an air display day at RAF Boulmer many moons ago when there was a very strong wind down the display line.

8 Sqn Shackleton did a slow pass down the line - then throttled back and drifted slowly backwards down the line in the opposite direction, before throttling up and accelerating* past the crowd for the third time and away. Very impressive.

*I know, I know, it was a Shack - but everything's relative. :)

[VinRouge]

Ive flown with a negative groundspeed in a bulldog and a tutor. Was chuffing windy though!

[longer ron]

I have done it in a T21 :)

Whats the stall speed of a Shak ????
Must have been REALLY FFFFFin windy to have neg groundspeed in a Shak !

[tarantonight]

Many thanks. Obvious now I think about it.

[BOAC]

I know, I know, it was a Shack - but everything's relative - (as is incest...) indeed, but to get all those rivets moving backwards and forwards together without losing any is no mean feat.

Time for the 'flying the circuit at White Waltham in a Chipmunk backwards' story again?

[Union Jack]

Time for the 'flying the circuit at White Waltham in a Chipmunk backwards' story again?

Hotly pursued by the Stringbag being overtaken by the sheepdog!:ok:

Jack

[Fox3WheresMyBanana]

Flown backwards in a Bulldog (and the bona jet, but I suppose that's regarded as cheating) at Leeming
Also climbed in no power glide attitude and descended at max rate climb due to mountain wave activity, also out of Leeming, under the hood on an early IF trip - definitely brain-scrambling! Power, Attitude, Faith. Ee, it's tough in Yorkshire.

[BOAC]

Ee, it's tough in Yorkshire. - aye lad, but tea's good.

Have you tried the effect on ATC if you come to the hover on a GCA? Even more impressive, I believe, is going back up the glideslope, but I recall this caused a nervous breakdown in talkdown:D

[MightyGem]

I have done it in a T21
Not really difficult in one of those, is it?

[Tourist]

Orac


Re the Shackleton going backwards.

Are you seriously trying to tell me that there was an air day which was not cancelled even though there was 100kts of wind?

Shackleton must have a stall speed in the 90kts range, needing 100ish to "go backwards".


Stringbag, yes it can be done and has been done on windy days.

Shackleton I think total bollocks unless you have evidence.

[ORAC]

Are you seriously trying to tell me that there was an air day which was not cancelled even though there was 100kts of wind? Yes. It was blowing a gale and nearly everything cancelled. Shack was about the only thing left.

[Melchett01]

Flown backwards in a Bulldog

Yep, done that one too in my UAS days. As I recall, Spin 3 or whatever it was called, flying with the Sqn Boss who was supposed to be demonstrating entering a spin during mishandled aeros. We managed to mis-handle the loop so much that we dropped out of the top of it into a tail slide.

To this day I still have no idea how on earth we managed it, but to a fly on the wall (canopy) it must have been priceless to see instructor and student sitting there, looking at each other and both instinctively thinking the same thing ... WTF?!!!!

[Cows getting bigger]

Stall 'speeds' - an interesting concept. When I were a lad I was taught about angles of attack, relative airflow etc I can quite happily entertain the concept whereby a Shack can travel backwards over the ground with a surface wind speed being noticeably lower than an aircraft's "stall speed". :)

[Tourist]

ORAC

"gale" covers up to about 40kts/Force 8

"Hurricane" is up to about 65ish kts/Force 12 and has the description:-


"Huge waves. Sea is completely white with foam and spray. Air is filled with driving spray, greatly reducing visibility.Very widespread damage to vegetation. Some windows may break; mobile homes and poorly constructed sheds and barns are damaged. Debris may be hurled about"

This though, obviously would not be anywhere near enough wind to make a Shackleton fly backwards down the display line.

Wiki reckons that Shackleton stall speed is about 88-96 kts (my first guess was not far wrong!)

To fly noticably backwards down the display line would require at least 100kts+ steady wind.

Have you ever tried to stand in 100kts of wind? Can you seriously imagine a crowdline under these circumstances?



Cows getting bigger

Yes, I am aware that stalling is only reliant on AoA, but it is perfectly valid to use an airspeed for an aircraft flying straight and level with no ballistic component, unless you are suggesting such an event?

Please entertain me with your concept where a Shack can fly in a sustained manner backwards down a crowd line at below it's stall speed. I am agog with anticipation.

This is an apocryphal story that perhaps people have not really thought about with a sensible head on.

Unless my guess and Wiki are wrong by about 50kts for the stall speed, this story is cr@p.

[jamesdevice]

SHACKLETON DATA (http://avroshackleton.com/shakspec.html) says the stalling speed for a Shackleton AEW2 was 92 mph (not knots)

[Tourist]

Ok, happy to believe that. Do you think that makes the story any more believable?

[jamesdevice]

No!
Just trying to aid accuracy as wiki is not exactly the font of truth.

[Mechta]

If the Shakleton was lightly loaded, at max AoA, and with a significant amount power on in fine pitch, maybe it was doing as described?

[ORAC]

All I can say is I stood there and watched it. Believe me or not; believe your figures or not. Makes no difference.

[Hipper]

In the case of the airbus film, was the pilot able to do this safely because of his computers?

I presume it would be very difficult to do this manually.

[longer ron]

Not really difficult in one of those, is it?

Absolutely...that was my point exactly LOL

Easier than dragging thousands of rivets at high AoA though eh !!

[davydine]

Hi All, not a pilot, or in the military but I hope you won't hold that against me. I assume that the Shak was climbing at the time? If so the ground speed would be significantly lower than the Airspeed.

Scratching around with A level physics but I think there is a cosine relationship between the airspeed and the climb angle... I have no doubt someone will correct me!

[Tourist]

davydine

"If so the ground speed would be significantly lower than the Airspeed. "


Yes, if the Shack was climbing at asteep angle, say 45 degrees or above, but hardly adds to the believablity of the story, does it, especially when it has to maintain that climb for enough time to make three passes of the crowdline.

Have you seen a Shackleton?!

ORAC

"Makes no difference"

I beg to disagree.
You have the username Orac and obviously spend a lot of time reading and posting aviation articles.
As such I would say that you are generally considered a knowledgeable/credible poster on this forum.
That credibility is not helped by flights of fantasy.

[Ivan Rogov]

ISTR wind generally increases with altitude, wind gradient?

Not being a stick monkey, what effect do the props have on the flying surfaces? better control at slow speed, directional stability?

Also what effects do contra rotating props have compared to standard ones? I'm guessing that they are required otherwise the blades would be too long and the tips go Mach 1, but are there other benefits?

[davydine]

Tourist,

Yes, I have seen a Shakleton, but sadly, only on the ground, I can't really imagine it "flying" backwards as has been suggested, it is ORACS claim not mine. The video from the OP shows an Airbus that looks to be almost hovering. I think the important word there is "looks"

What is the difference between the stall speed of the Shak and the Airbus I imagine the bus is higher.

Just trying to work out if it is possible, not if it actually happened...

[Thud105]

Four Griffons turning contra-props blasts a lot of air back over the wing Ivan, which would generate a lot of induced lift. However, not enough for a Shack to fly backwards I suspect.

[jamesdevice]

Ivan Rogov
The contrarotating props come from Spitfire days when the power produced by the Griffin would have needed a blade diameter bigger than provided by the undercarriange height.. They simply then used the same arrangement on the Lincoln for convenience - the epicyclic gearbox worked, produced a more efficient linear thrust, so why bother changing it?

[Ivan Rogov]

Every day's a school day, thanks :ok: