TV of Hornet behind Hercules - Wake Turbulence?

[A37575]

Melbourne TV Channel 9 showed a beautiful shot of an RAAF Hornet formating on a Hercules and sitting just a few metres behind the Herc's open ramp. Despite being that close the Hornet was clearly unaffected by the Hercules wing tip vortices or propeller slipstream. Years ago I saw a picture of a USAF Hercules flying between to tall masts from which emanated coloured smoke. The wing tip vortices from the Hercules were shown in colour quite dramatically and was proof of the presence of vortices. That being so, I wonder why the RAAF Hornet was unaffected behind the Hercules over Melbourne, today.

[Hugh Jarse]

Possibly because line astern (and in tight) behind the ramp of the lead aircraft is well clear of the wingtips and the associated vortices?:E

[VH-XXX]

Nah, I watched them flying around South of Melbourne today. They weren't that close and the Hornet was generally under the Herc. The TV made it look really close.

[Buster Hyman]

Saw that from my "lofty" office in the CBD. Didn't see the footage but from the angle I saw, he wasn't lined up, centre d on the Herc's fuselage. Initially I thought the Hornet was "hooked up" for fuel, but the angle he had it was quite impressive...trying not to "dock" with the aft cabin on the Herc must be fun.

I guess the sheer power of the twin F404's would negate the vortices rather niftily too!

[control snatch]

Duh

How do you think we tank from big aircraft?

You just deal with it

[Buster Hyman]

:confused:???

Oh. Never mind, just saw your age!:ok:

[No Further Requirements]

You knucks just can't help yourselves, can you? control snatch, the guy was just asking a question. How about 'you just deal with it' and explain it nicely.

:hmm:

Cheers,

NFR.

[Arm out the window]

I've flown close-ish form behind a Herc as part of a gaggle of PC-9s for photo purposes - when in behind the fuselage, as you might expect, there weren't any dramas, but when manoeuvering out wider, definitely got thrown round a bit, nothing too startling though.

[Brian Abraham]

Loved the TV report "they screamed (or was it roared) across Melbourne". Those Hercs must be real goers.

[Buster Hyman]

I think it was the cameraman hanging out the back door that was screaming.

http://www.news.com.au/common/imagedata/0,,5421881,00.jpg

Pretty mixed bag under the wings there...no wonder he's listing to the port side a bit...:rolleyes::ugh:

[Capn Bloggs]

NFR,

My sentiments exactly.

Betcha he flies around with his visor up and gloves off. :yuk:

[Cloud Cutter]

Tip vortices don't develope into decent wake turbulence until a fair way behind an aircraft (they're too tight to start with). Also a straight winged aircraft like a Herc doesn't give off as much turbulence as a swept wing aircraft of the same mass. Couple that with the high wing loading and exceptional roll capability of something like a Hornet, and it's doable.

[luvmuhud]

The wake vortices of a large transport aircraft definitely do have the capacity to throw a fighter around. However, the effects are generally limited to the outboard wing area, and only when fairly close to the plane of the wing. Line astern is completely free of these effects. In distant history, a RAAF Hornet was 'thrown' over the tail of a B707 by the wing tip vortices (ended up almost inverted behind the opposite wing from which it started!).
Generally, when sitting in the correct tanking position behind a wing mounted refuelling pod, you will need some outboard aileron trim to counter the effects of the vortices which you are generally positioned right on the edge of.

[trashie]

Try No4 in a C130 line astern. You certainly know when you are in the wrong spot.

[slinky daddy]

My sentiments exactly.

Betcha he flies around with his visor up and gloves off.

Dont forget the "flick the mask off before the thumbs up" :hmm: :ok:

[ScottyDoo]

Can I also join in in saying the same thing?

The wingtip vortices are found aft of the wingtips. The Hornet, as you said, was near the ramp. No wingtip vortices to be found at the ramp because there are usually no wingtips there.

Also, the turbulence "streams" aft at a higher plane than that which the Hornet is occupying, thus his smooth flight.

At least, there are no vortices from the camera ship the Hornet is following - but there could be another Herc in front of and offset to the camera ship... ha, you never thought of that, did you???

I do approve of your use of the correct terminology - 'vortices' - rather than 'vortexes' as many of our less-learned professional aviator friends seem to prefer.



The real issue is why these planes were sent up at great expense to the taxpayer to do nothing more more than lark about taking photos. These RAAF pilots obviously take great delight in flitting around the skies in their - our - planes having a jolly. And over the city?? What about the noise?

Absolutely disgraceful waste of money.

[Captain Sand Dune]

The real issue is why these planes were sent up at great expense to the taxpayer to do nothing more more than lark about taking photos. These RAAF pilots obviously take great delight in flitting around the skies in their - our - planes having a jolly. And over the city?? What about the noise?

Yes, I think it's outstanding fun! :} And better yet, I'm being paid to do this sort of stuff.:ok:
Careful, your chip's showing.:hmm:

[Buster Hyman]

No wingtip vortices to be found at the ramp because there are usually no wingtips there.
Well, looking at that picture, I can see two just above the ramp. ;) Okay, I'll probably get a right RAAF flaming for this but... what, if any, vortices would be produced by the tail section? I guess the sheer area of the main wing is the cause of the vortices but, would there be any off the tail, or would the fuselage negate it, or is it just plain insignificant?

http://www.clicksmilies.com/s1106/spezial/Fool/pom.gif

[ScottyDoo]

the sheer area of the main wing is the cause of the vortices

Vortices.

Formed, regardless of the area of the wing, from the disparity between the high pressure below the wing and the low pressure above the wing as the air escapes the one in search of the other, in a circular movement.

The ramp area just causes what we in the industry refer to as "tur-bu-lence".

Once again, the money-wasting knuck was clearly flying our plane well below the affected area. Proof that our money spent on his training was not wasted, unlike the money spent on this gay, jolly flight of fancy around the city.

I hope he really enjoyed himself, flying his - our - plane around the skies like that.

[Buster Hyman]

Poorly phrased by me... :rolleyes: ...the vortices that have a significant effect on the trailing aircraft would be proportional to the size/area of the wing? Or do you mean that the vortices' from the tail could have the same effect???

That sounds like, what we on the ground refer to as, "ree-dick-you-less"!

:rolleyes:

[ScottyDoo]

I think aspect ratio and weight have a greater effect on the magnitude of the vortices.

As for Or do you mean that the vortices' from the tail could have the same effect

I presume you're referring to the horizontal stabiliser? But if the aircraft is in balance, wouldn't the elevator deflection be minimal? Since it is not a lifting surface, I'd guess the tendency to towards vortex-creatin due to lift would be almost nil.

What are you really asking? You're confusing me with your grammar. Are you a pilot?

[Buster Hyman]

Are you a pilot?

WELL! There's no need to be insulting about it!!!:suspect:

I actually meant the stabilisers but, seeing you are saying that its all to do with the lifting surfaces (if I'm reading you right?) then I think I have my answer.:ok:

[ScottyDoo]

I'm glad. Any more questions and my ignorance and BS may have been exposed, if it wasn't already.

I still maintain these elitist knucks should spend less time burning kero carelessly for no reason other than the pure, unabounded joy of it and more time contributing somehow to our society.

We can only hope he has some really ****ty secondary duties...

[Brian Abraham]

I presume you're referring to the horizontal stabiliser? But if the aircraft is in balance, wouldn't the elevator deflection be minimal? Since it is not a lifting surface

Aerodynamics 101 - Purpose of horizontal stab/elevator
Nah, never mind, I'll go proon the hedge. :suspect:

[Swingwing]

Buster - good question. And I'm sure you know the purpose of the horizontal stab, so thought the flaming was a bit unnecessary!:)

Short answer is yes - there's a whole lot of "mess" coming off the vertical and horizontal stabs. The way to stay out of it is to stay below the plane (geometry term, used deliberately ;) ) of the tail-plane!

As with the wingtip vortices, the wake turb behind the fuselage / stab sinks at a relatively low rate, so you can get in behind without a problem. That's why line-astern formations always have a vertical difference between the lead and wing aircraft, with the wing sitting low.

In fact, in some types, that's how you pick the vertical spacing in close line astern. In the Pig, you're in the correct vertical position in line astern when you can just feel the "burble" of turbulence through the stick. Get too high and it gets rapidly stronger and can eventually spit you out if you're too ham fisted about it.

Same principle when tanking from a centreline boom - stay low enough to be out of the wake. get too high and the boom operator will cut you loose (due also to potential boom damage, but I won't bother with that here.)
Hope that helps.

ScottyDoo - nice wind up mate. Knucks "contributing to society"? Perhaps by pumping up sales of hair gel and raybans?

As they say - "fighter pilots make movies. Strike pilots make history" :cool:

Anyway - get over it. It's called PR, and as I'm sure you know it is about generating publicity for 1) Avalon specifically and 2) defence generally.
It IS part of the job.

[kiwiblue]

the vortices that have a significant effect on the trailing aircraft would be proportional to the size/area of the wing?

From memory BH, vortices are proportional to the weight of the aircraft creating them, rather than the size/area of the lifting surface.

[señor_jones]

"I still maintain these elitist knucks should spend less time burning kero carelessly for no reason other than the pure, unabounded joy of it and more time contributing somehow to our society.

We can only hope he has some really ****ty secondary duties..."

ScottyDoo,
I wouldn't think that tooling around at half pace in close formation with a herc is one of the more 'joy'-ful things you could do in a hornet.

Sounds either like a good windup or you've got a big chip on your shoulder. Did some mean-spirited knuck roll in on a girl you were trying to impress one time? At band camp. Please do tell.

[ScottyDoo]

Si senor. You obviously don't get irony in meh-hico, eh gringo?

It's called irony. I could disassemble it in an attempt to explain to you how I say one thing when really I mean another but by then the moment has probably passed.

Rest assured, I have no problem with knucks in Hornets burning kero or "doing" aeros or wasting hours or pulling their puds.

Better the money is spent on something satisfying like that than frittered away on an orphange or the like...

[señor_jones]

ScottyDoo,
Thanks for the impromptu grammar lesson. A convenient tool when one is not sufficiently informed to have an actual opinion either way. Great example.

Given you find it appropriate to change my quote to reflect your personal experience, please share the rest of the story with us so that we might all avoid the humiliation of having some knuck walk out of a bar, up to his second knuckle in some girl you thought you had a chance with 3 minutes earlier.

[bushy]

Some very mature, friendly people on here, really adding to a valuable discussion?????.

[Brian Abraham]

Scotty, An honest question in order to how much weight to give your posts. What are your aviation credentials, the profile is a little slim on specifics.

[Arm out the window]

He doesn't mind a bit of **** stirring, anyway - amusing for a little while, then not.

[ScottyDoo]

Sorry senor, that was a phrase I picked up in the RAAF. I thought I was talking to a fellow and you might notice it but I guess not.


Note to self: Use the wink-smiley next time you want to make a friendly jibe at the RAAF....