Diving with open Airbrakes....

[November4]

I know this is going to stretch the memories of even the more “senio” members of this forum but thought I would ask this question all the same.

Have just shown a gentleman and his family what is believed to be the site where his brother died in 1945 when his Meteor of 504 Sqn crashed. Another pilot who was flying with him said

We were practising diving with open airbrakes.

The question was asked what is the significance of the open airbrakes comment?


Mods - if this is more appropriate in another forum please feel free to move. Thanks

[Art Field]

The Meteor airbrakes were on the wing and worked by providing drag but also by disturbing the airflow and therefore the lift over the wing. This was why the airbrakes should never be used when lowering the undercarriage with the left/right (or was it right/left) main sequence. I have a vague memory of a trim down change when airbrakes were used in the dive which would hardly be an ideal situation and would need careful handling, perhaps somebody can recollect better than I.

[Double Zero]

Might do better on the Flight Testing thread; I would think the airbrake question is specific to the type, in this case Meteor.

I'm no Test Pilot ( cue for someone who is ) but I'd guess diving with airbrakes already deployed is generally OK - depending on the mechanical setup - but reaching warp 9 in a dive then expecting to deploy the brakes might be asking a bit much, and there's the risk of asymmetric opening or failure which would be a bad thing.

[Yellow Sun]

I'm no Test Pilot ( cue for someone who is ) but I'd guess diving with airbrakes already deployed is generally OK - depending on the mechanical setup - but reaching warp 9 in a dive then expecting to deploy the brakes might be asking a bit much, and there's the risk of asymmetric opening or failure which would be a bad thing.

You don't have to be a TP to sort this one out. A set of airbrakes that you couldn't deploy at high speed in order to prevent you exceeding the airframe limit would definitely be in the "Chocolate Fireguard" category. The above applies to a clean configuration, the situation may well be different with flaps/slats deployed

YS

[CirrusF]

The question was asked what is the significance of the open airbrakes comment?



I'd suggest he was just painting a picture of the day when the accident happened and he could equally have said "it was a nice sunny wednesday afternoon" or such like. The airbrakes on the meteor were inboard of the engines and on both the upper and lower surfaces of the wing - ie so that they would significantly increase the drag with no disruption of the airflow over the ailerons, which is a very benign configuration and very unlikely to contribute to an accident.

[CirrusF]

So the Meteor had airbrakes on the inboard section of the wing then. Help me out here - is that the bit in front of the elevators?
http://static.pprune.org/images/statusicon/user_online.gif http://static.pprune.org/images/buttons/report.gif (http://www.pprune.org/report.php?p=4964526)



The section of the wing between the engines and the fuselage.

The outboard engines on the meteor acted as large aerodynamic fences on the wings and so airflow disrupted by the airbrakes did not affect the ailerons - a benign configuration compared to some other aircraft with wing mounted airbrakes.

[soddim]

Suggest you look at the following link - it appears that the use of airbrakes could prove fatal in the landing configuaration and I recall an accident to the vintage pair where this was the possible cause.

http://www.pprune.org/military-aircrew/70987-meteor-accident-statistics.html

There was also the problem of "The Phantom Dive". In the T7, and maybe in the single seaters, you never selected airbrakes out with the gear and flap down otherwise the airflow over the back end effectively ceased and the thing just went down. If I remember correctly, this problem was made worse by the close proximity of the airbrake and the flap levers, both in the same place and both acting in the same way.

[henry crun]

The only restriction on using the airbrakes was, as already mentioned, when lowering the undercarriage.
Apart from that they could be used in any situation regardless of speed or attitude.

It was normal to use them in descent to prevent speed increase; perhaps that was meant by "practising diving with open airbrakes".

[wiggy]

And if I recall matters/events/BOIs correctly the "Phantom Dive" ( as in Airbrake out whilst lowering gear) was still causing fatalities on the Meteor as late as 1988 :sad:

[henry crun]

wiggy: Broken Wings records only two accidents after 1960 for which the cause was unknown, so might have been a Phantom Dive.
One of those was in 1962 and the other in 1965.

I did not bother looking back any earlier than 1960.

[henry crun]

November4: Given that the accident you refer to took place in 1945 when jet aircraft were still very new, it would have been a novel experience for any pilot to fly an aircraft with airbrakes.

That combined with the unusually rapid accelaration in a dive compared to previous piston engined fighters, maybe ''practising diving with open airbrakes'' was part of the conversion to Meteors.

[November4]

Gents

Many thanks for the replies. As this has generated a lot of interest, This question was the crash of Meteor III EE288 on 8 June 1945

A few more details from the same source:


We were practising dives with open airbrakes, starting from an echelon formation and peeling off one behind the other. F/Sgt Chase some how got into a spin and didn’t succeed in pulling out.

Meteors were not easy to get out of spins, in fact at the time we weren’t allowed to spin them or risk getting into a spin as we had no ejection seats and baling out without one was not possible on account of the high position of the tail unit.

Another pilot said at the time

…it appeared to carry out a climbing turn to the left – which may have been the beginning of a roll. The aircraft went straight into a spin, first to the right and then to the left in a 180 degree rotation as though the pilot was over correcting, this continued until the aircraft hit the ground vertically and burst into flames.

The F1180 recorded

Duty – Aerobatics not below 6,000 feet
A/C seen to stall and spin in from approx 4,500 feet
Aircraft out of control
Cause of crash aircraft stalling and flicking onto a spin. Contributory factors pilots inexperience and starting aerobatics below authorized height.

[CirrusF]

Go on Cirrus try harder!

Some clues (again) -

Dive
Pitch
Tailplane
Elevator
Inboard wing-mounted airbrakes
Aerodynamic 'fence'


Are you trying to suggest that the Meteor lost all elevator authority as soon as airbrakes were deployed? Clearly not, so what is your point?

[Yellow Sun]

JtO

Lots of ac have speed limits for airbrakes, including a lot of modern FJ ac (inc such ac as the F-15).

Even the Tornado schedules its airbrakes according to Mach number

I have flown an aircraft with speedbrake scheduling and am aware that there are others. However I am not aware of any aircraft that has an upper speed limitation for selecting full speedbrake. The built-in protections may not actually give you the max available angle, but it will give you the max allowable.

However I should be very interested to know of any type that has a maximum speed limit for selection of speedbrake.

YS

[BEagle]

VC10 had a speedbrake limit of 345KIAS.

During the high IAS run on Full Flight Tests, we increased speed to 350KIAS, checked the speed warning horns, flying controls and TPI, then checked that speedbrakes could not be selected - the lever was held in. Whilst maintaining pressure on the speedbrake lever, speed was reduced to 345KIAS to check that the speedbrakes would then extend to the normal baulk limit.

Didn't the Lightning also have an airbrake limit?

Trim changes in some aircraft were quite significant. Descending the Vulcan you were supposed to select mid-drag airbrake, allow the nose to pitch down (took about 7 seconds), then idle thrust and finally high-drag when stabilised in the descent........

As a youngster, I thought I knew better. So selected high drag, closed the throttles and then started to dive off the height against drag to achieve a higher descent rate than with the normal technique......and then the trim change suddenly made its presence known and the dive (from FL450) became rather steeper than anticipated, rapidly reaching M0.95+. At such speeds, considerable elevon is automatically applied by the auto mach trimmer, so there isn't much left for pitch control until the IAS increases in denser air lower down. Which it did.

Nearly dropped a HUGE sonic boom - over HQ 1 Gp RAF Bawtry, coincidentally!

Since then I've flown as the QFIs taught, rather than trying something else!

[Mike Read]

Getting back to the Meteor, the airbrakes were extremely effective with no max speed for deployment. If I remember correctly the max permitted speed of the aircraft was 520kts which could only be achieved at low level, and on a calm day. It was exhilarating. In turbulence it was worrying! (I'm thinking 1951) But the real test, flying level, apart from seeing the fuel gauges unwind, was to pull the airbrake lever fully back. It was like hitting a brick wall. In later years (1969) when occasionally flying the Chivenor target tugs I felt it unwise to exceed 400 kts as the airfames creaked and groaned alarmingly. I seem to remember that at about that time a modification restricted the maximum airbrake extension.

In my instructor days at 210 AFS we demonstrated spining in the T7s. Again, if my memory is correct we always started above 25,000ft. It was reluctant to enter a spin but when it did it was necessary to keep a firm grip on the stick which tended to thrash about and could leave nasty bruises on your knees. Recovery was normal. One instructor, Athol MacIntyre, demonstrated to his students that providing you had sufficient altitude simply by letting go of the controls the aircraft would recover of it's own volition leaving the pilot to "regain straight and level by pulling out of the ensuing dive". Happy days!

[CharlieJuliet]

A quick check of some stuff that I have shows that use of the airbrake on the Lightning F3 and F6 airbrake was limited to 650/1.3 and on the T5 to 650/1.2. The Meteor T7, F8 and F9 had no limit.
The Meteor T7 Pilot's Notes say:

If the aircraft is yawed at speeds below 170 knots with the airbrakes out, the nose may drop suddenly and the elevators become ineffective until the yaw is removed or the airbrakes retracted The tendency is aggrevated if a ventral tank is fitted. Airbrakes should not be used at airspeeds below 170 knots at circuit height and should be in before the undercarriage is lowered.

There is no such warning in the F8 F9 book.

[CirrusF]

Athol MacIntyre, demonstrated to his students that providing you had sufficient altitude simply by letting go of the controls the aircraft would recover of it's own volition leaving the pilot to "regain straight and level by pulling out of the ensuing dive". Happy days!


That's not unusual - most (but not all) aircraft do recover from a spin if you release pro-spin controls, albeit more slowly than if the pilot applies contra-spin control.

[shack]

As an ex-Meteor QFI I can assure you that to have airbrakes out in the circuit and then lowering the u/c was a big No No. There was a tendency for the legs to lower at a slightly different rate causing the start of a yaw which combined with the confused airflow over the back end meant you were only going one way -- downwards, known to one and all as the "phantom dive".

[VictorPilot]

Hey Guys, I remember the loss of a lot of good pilots doing things with the Meteor airbrakes when they should not have!! But it was not only the Meteor, the Vampire had good airbrakes - but airbrakes and full flap was a no-no - I tried it once when doing a break on a conversion sortie, and I still remember the nose down plunge that resulted!!

But it always seemed to me that having an upper limit on the airbrake deployment was a total contradiction in terms. The time you needed airbrake above all was when you were going, or about to, too fast!! (IAS)

QV The Victor. None of your pretty pansy Vulcan airbrakes .... Great big barn doors at the back end that did not affect wing or tailplane airflow. The good book said the max was XXXX I cannot remember, but that only reflected the authorised max speed for the airframe as a whole. In the high altitude days, we used to do high speed runs on the conversion course with and without the Mach Trimmer - very different!!!! But the technique was the same. With cruise power applied, nose down to a steep angle - not sure what it was - hold the attitude with speed building up, at M.96 throttles closed and airbrakes out - hold the attitude and stabilise at M.98 WOW

In later years, the original clean and speedy B2 had steady reductions in its limiting M number - fixed nose flaps, tanks, pods etc etc - but the airbrakes could be used throughout and beyond the cleared flight envelope.

Interestingly, in the early Victor days, the handling SOPs relied much on Canberra and Meteor and other aircraft SOPs. Part of this was it was taught to be "bad form" to use the airbrakes on the approach. This was ridiculous on such an aerodynamically clean aircraft; all the co-pilot did on the approach was "Up 2%" "Down 2%" etc etc.... In 1961, common sense prevailed on the B2 with its high residual thrust on the approach, and a "Variable progressive" use of the airbrakes on the approach became SOP until the aircraft retired.

Now I sit in a window seat of a 777 and watch what seems to be half the wing open up on landing to lift dump and produce drag, and I still prefer the Victor!! What a forward looking design that was!!

Bob

[Tankertrashnav]

I still prefer the Victor!! What a forward looking design that was!!

Hear, hear Bob. The following is copied from my post on the two Vulcans at Wellesborne thread:


A 1955 Victor B1 in anti-flash white before they started sticking all the bits and bobs on still looks like something from the future.


Pity it's the ugly one thats still flying!;)

[Ali Barber]

Reference the earlier Lightning comments, M1.3 was a speed switch as far as I recall. Above that they did not come out at all.

[CharlieJuliet]

Agree, the Aircrew Manual says 650/1.3 for the F3 and F6 and 650/1.2 for the Tub

[Jig Peter]

On the single-seat (i.e. REAL !!!) Vampires and Venoms I remember the stick moving noticeably forward as flap went down - visiting genii from the Central School of Driving Aereoplanes once told us 2TAF mud-moving squadron drivers that this was NOT a trim change, but due to changing airflow over the tailplane ... seemed like a trim change to us nevertheless ...
The above gentle people were also a bit smiffy about our landing techniques - stick back after mainwheel touchdown for max braking, then let the nose-wheel drop gently onto the runway ... If bored while all this was happening, use left hand to wind back the canopy and let some fresh air in. They said this had about as much effect as hanging a knotted handkerchief out, but I don't think anybody put that to the test.
After flaps down, the airbrakes could be used to try to soak up some speed on finals: I don't remember that they really had all that much effect either, but at least we tried ... Aaaah de Havilland !!!

About the mighty and beautiful Victor 1 - those barn doors were great on the approach, and at one stage there was an idea to use constant engine rpm, controlling speed with the airbrakes - but it was soon clear that traditional methods were OK (even to asking for "1/2%" rpm changes - remeber those tiny dials ??? )... Cocky or what ???

:8

[henry crun]

Jig Peter: Re the stick moving forward with flap selection, IIRC it used to move forward just enough to completely obscure the compass.
Just what was need on a GCA !

VictorPilot: Good airbrakes on a Vampire ? I suppose it depends on what you are comparing them with.
I thought they were pathetic after the Meteor.

[Lightning Mate]

"Agree, the Aircrew Manual says 650/1.3 for the F3 and F6 and 650/1.2 for the Tub"

If I remember (and I flew the 3, 5, and 6), 650 kts was the IAS limit.
In terms of dynamic pressure, therefore, there was no IAS limit on the use of the brakes.

[Jig Peter]

Agreed that the Vamp's airbrakes weren't all that world-shattering, which the Meteor's certainly were before the Phantom Diver struck and their travel was limited, after which they were just "slowing down thingies", I think ...
But you are so right about "stick forward into the G4" - needed the seat high and a spot of peering about with head on one side, IIRC ... Didn't stop us from getting safely down in some claggy North German weather though ...

On reflection, I think our Vamps had the "spade grip" stick and DGs for heading, while the Venom had the stick grip and a G4B. But in both cases I don't remember problems seeing one's heading was doing on GCA finals with full flap, perhaps because our GCA controllers had such a reassuring patter ... :)