Why does the Typhoon vent fuel in displays

[18greens]

I was curious about the reason the aircraft vents fuel during its displays (assuming its not deliberate). At the rate it consumes fuel I would have thought the waste would be avoided if possible.

[taxydual]

It's possibly not fuel venting you see. Maybe water vapour, created by the sooper dooper wing thingy, passing through moist air causing a fuel vent effect.

Those 12 hours I had on Bulldogs were not entirely wasted.........:)

[NutLoose]

The jaguar used to vent it all the time, just a poor seal on the vent valve allowing fuel out you could often only see a Jag at low level because of it.
I do not know about the Tiffy.

[superq7]

18
You can see the same effect on F1 cars in wet conditions.

[smujsmith]

Vacuum sucks, valves seep, Sh1t happens. The Typhoon is a cracking jet, much envied by our cousins across the water (past Ireland). You may also be seeing wing tip vortices generated by the bits and bobs hanging on the aforesaid wing tips. As they say "up north", " there's naw't wrong wee what you're seeing". Nice effect I think myself.

Smudge

[gijoe]

The VC10 does this as well...or maybe it is the cracks in the wings?

VC10 Display Routine:

Pitot Heat: On

Pitot Heat: Off

...so it can't be intentional.

Where is BEagle?

I will never forget the departure from Brize bound for the US , someone spotting the leaking wings, quick dive back to Brize...and the crew jumping off first leaving 130ish ICSC(L) studes wondering what is going on.

It was pure comedy.

G:ok:

[taxydual]

And (bad grammer, I know) the Shacks, bumbling out from their apron onto Lossies'' Rwy 23 used to dump gallons of AVSMELL. The poor Caravan Controller couldn't light a fag for hours.

[smujsmith]

The gallons of Teflon paint I applied to the underside of 56 Squadron ( RAFs " premier Lightning squadron") main planes, to no avail. As I recall, one of few aircraft allowed to have drip trays positioned for Royal Inspections.

Smudge

[betty swallox]

So. Really none of the above comments relate to the blokes question about Typhoon.
Well done.

[taxydual]

betty

This is PPRuNe. What do you expect?

[thing]

Nor does your comment.

[smujsmith]

Betty,

It's an old British trait, as few who post on here have current experience on Typhoon, and therefore are not competent to appraise the OPs observations on that type, we have tried to proffer similar experiences on types we are familiar with. Would you rather the OP met with no response at all ?

Smudge

[thing]

Taxi just noticed your location. Half of the graveyard in Bedale is filled with my ancestors the Joys.

[Courtney Mil]

Because that part of the fuel system comes from the Tornado and has been used as a "one size fits all".

[NutLoose]

Actually Bettie, I did add I do not know about the Tiffy at the bottom, you obviously skipped that bit. For what it's worth a vent valve is a vent valve, is a vent valve, regardless of period built some of the core parts do not develop much beyond what works. And no matter how complex a fuel system it will still need one be it a modern fighter or a 1911 car.
Wut Smudge said...




..

[betty swallox]

Fair point. However my point was that comparing a Jag to a Typhoon is as much use as A Nimrod to a Herc. Totally different fuel sys etc. that was all. No need for the defensive comments!!
Whilst I understand this is a rumour site, I'm betting the originator is more confused than anything else...

A simple point met with much noise.

[NutLoose]

Added a little to post. Sorry if it came over as being defensive, wasn't intending it to be.


..

[gijoe]

'So. Really none of the above comments relate to the blokes question about Typhoon.
Well done.'

You utter, utter, utter, tube.

Enjoy your transition - I am sure it will match your expectations.

You will be great in CivDiv.

G:ok:

[betty swallox]

A true gent. Thanks. And my intention was far from trying to be antagonistic
Time for a beer...

[betty swallox]

Ah. Gijoe

My point exactly. Thanks for making it!

[gijoe]

___________________

[NutLoose]

Now I'm lost.

[betty swallox]

Me too. I'm going for a pint. I didn't really want to get the abuse!!

[gijoe]

_______________________________

And I'll buy it on your resettlement course.

[thing]

I saw a hedgehog today in my garden.

[NutLoose]

With you Betty...

Remember don't feed the Hedgehog bread.... Same goes for trolls.



..

[gijoe]

It seems that Spiney the Hedge is getting around a bit at the moment.

Last seen at RAFC on 21/8/13.

Where next will be Spiney?

G:ok:

[betty swallox]

Oh look. A squirrel....!

[DX Wombat]

Flying pig anybody?

flying pig - YouTube

[Rhino power]

With regard to the original question, yes, the Typhoon does dump fuel during its display. One of the best examples is the 'negative g outside turn' performed during the 2013 display routine (which is the best display yet and utterly spectacular by the way...) The dump vent is above the rudder so there is no mistaking it for vortices coming of other parts of the airframe, hope that helps!

-RP

p.s. I should add its a small amount of fuel vented in the grand scheme of things...

[gijoe]

Who mentioned PAS?

Unfair to invite them unannounced.

G:ok:

[CoffmanStarter]

DXW ... Went looking for one of those once :ok:

[18greens]

Rhino, thanks for the reply. Agree with negative g outside turn being splendid.

Any idea what is happening in the fuel system to make it want to vent. I presume the vent valve is a pressure relief system. I suppose the -ve g just creates the over pressure .. in which case why doesn't it dump all the fuel....

[DX Wombat]

CS, I live in hope of finding one but I fear they became extinct around the time common sense (http://www.politicallyincorrect.me.uk/commonsensedeath.htm)vanished. :{ :{

[Al R]

Thanks Rhino. Going off topic for a moment, that must be uncomfortable - what sort of negative G is applied to the pilot during that? Without asking for sensitive info, how much more effective is the gear worn these days (than the few trips I had in a T-4, 20 years ago for instance)?

One of the best examples is the 'negative g outside turn' performed during the 2013 display routine (which is the best display yet and utterly spectacular by the way...)

[ExRAFRadar]

Rhino how dare you hijack a thread.

Oh wait, hold on......

[Rhino power]

Rhino how dare you hijack a thread.

Oh wait, hold on...... :)

18greens, i assume the once the pressure in the fuel system is equalized for the negative g element of the display the fuel dump stops, given the short duration i would guess it doesn't take much to in order to do so, just guessing on that though...

AI R, i'm not privvy to any detailed info re the flying kit Typhoon pilots wear (being a civvy) but, i do seem to remember watching an interview with Craig Penrice(?) where he is describing the flying clothing and along with the normal g-suit (on which the zip was fastened by pulling it down rather than up), he also wore g-booties, or, socks if you prefer to provide even greater g protection...

-RP

[TEEEJ]

One I took at Duxford 2009 showing fuel vent.

http://i66.photobucket.com/albums/h261/TOMMYJO/DSC_0144DUXSEP09.jpg

View from 1:57 and 2:34 for fuel vent during a display at RAF Cosford Airshow

RAF Typhoon Display Cosford Airshow - YouTube

[cornish-stormrider]

Goddamn that's a pretty sight,
Just curious for any sooties still in with comparison of EJ200 vs RB199 experience, better or worse to fix, no hateful module 12 thermocouples to do?
And am I right the 200 has a variable con Di nozzle?

Thrungy and pointy

[TurbineTooHot]

Al R, if I may, the G protection is phenomenal: Full coverage anti g trousers, a natty jacket which does a variety of pressure bits(inflation and breathing), and yes the socks (somewhat gaffed by many) offer the kind of protection against +Gz induced problems that snapping to then sustaining +9G is not really an issue. As with every other type of G protection, there's not a great deal that can be done about -Gz short of a spot of throttling, so we don't tend to bunt all that much.:D

To answer the original Q, yes the fuel over pressure relief drain can get a bit of fuel pushed up it during -G so we don't tend to bunt all that much.;)

[High_Expect]

Harrier..........

[smujsmith]

Teej,

Cracking photograph, thanks.

Smudge :ok:

[Rhino power]

And am I right the 200 has a variable con Di nozzle?

Yes, EJ200 does have a convergent/divergent nozzle...

-RP

[EAP86]

The vent system is probably working as intended. Its main function is to prevent high differential pressures across the fuel tank wall; fairly key for CFC structure. These can arise from either high climb and dive rates or from high delivery rates from the tanks. Any fuel migrating into the fill and vent lines will be lost overboard as the valves open. The 2:34 one is probably due to the steep climb; 1:57 just might be fuel slosh from the vigorous manoeuvres.

The interesting bit of the photo is the vortices shedding from the 'moustache' strakes on the avionic bay doors. They work to help the fin and directional stability at high incidence.

EAP

[thing]

AI R, i'm not privvy to any detailed info re the flying kit Typhoon pilots wear (being a civvy) but, i do seem to remember watching an interview with Craig Penrice(?)

That name rings a bell, ex Lightnings? Pretty sure he or his namesake were on 5 at the end.

[Rhino power]

That name rings a bell, ex Lightnings?

Yes, ex Lightnings, had a nasty ejection from a Hunter in 2003 - Penrice_Craig (http://www.ejection-history.org.uk/project/Biographies/P/Penrice_Craig/Penrice_Craig.htm)

I think he used to post on here as 'Tarnished'?

-RP

[thing]

Nasty indeed. Remembered why I know his name, behind me as I type is a framed picture of a Lightning with all of the last guys signatures on it, including his! Doh...

[Bill4a]

Smuj,
I was reminded of the gallons of PRC I pumped into the wings, it did work for a bit!

[RetiredF4]

I'll bite and try to add to the various explanations.
First the humorous one: It' s a wet system machine and as long as it is venting fuel there' s everything ok, enough of it still available.

Now to the logic explanation. The tanks are pressurized, to prevent the collapsing of the rubber type self sealing fuselage tank cells during high g maneuvering (at least that was the case in aircraft like F4 and other pre typhoon jets).

In normal operation the tanks are kept full by the transfer pumps (external and internal transfer), and when no transfer fuel is available those tank cells will go empty and stay empty, therefore there will be no repeated filling and emptying of single tank cells. They are either full or while getting emty they are pressurized with bleed air and stay pressurized until landing.

During display asociated with high powersettings the fuel volume of some cells will decrease, as the internal or external transfer pumps are not able to refill the tanks in the same time as fuel is used by the burners. The depleting fuel volume is replaced by pressurized bleed air. When the tank cells fill up again the bleed air is vented overboard, thus taking some fuel with it into the vent lines, especially just prior full fuel state of the respective cell is reached again.

Hope that helps.

[18greens]

RetiredF4, thanks for the explanation, makes logical sense. I hadn't thought about the rubber tanks collapsing and I can see the fuel venting as the air is expelled.

Now will I be able to remember all of that at next years airshow.

[stickmonkeytamer]

http://i367.photobucket.com/albums/oo116/sband/typhoonventing_zps2c7b2423.jpg (http://s367.photobucket.com/user/sband/media/typhoonventing_zps2c7b2423.jpg.html)

Late evening venting and spluff...

SMT