Harrier GR7

[Port Strobe]

I wasn't exactly sure whether this post ought to be in the Tech Log or here but reckoned I'd maybe have a better chance of catching John Farley in here if not a Harrier pilot! Whilst watching the Harrier GR7 display at RAF Leuchars yesterday I noticed that there appeared to be some sort of hinged panel open during hovering manouevers, its located just aft of the rear (hot??) nozzle on the underside of the aircraft. I'm just curious as to what its function is as I've never noticed this before. I'd also like to say it was another fantastic display of what is an incredible aircraft, still the best around by far! The display conditions looked extremely testing, very strong winds blowing all day. Anyway, I digress, if somebody could tell me the purpose of this panel I'd be grateful thanks, its probably something very simple no doubt but I'd never noticed until yesterday. My first thought was it might possibly be an airbrake but I thought its unlikely seeing as I've never seen an airbrake on the underside of an aircraft before and if it was it would produce a nose down pitching moment which I don't think is desirable in most cases. Thanks for your time

[dmanton300]

It's the airbrake. Located immediately aft of the main wheel well on all Harriers.

[NigelOnDraft]

PS...

Right first time - it's the airbrake. Quite a lot of Brit Mil aircraft have these ventral airbrakes - Hunter, Hawk, Harrier to name a few.

It's obviously not acting as an "airbrake" in the hover. Instead, it comes down with the gear, and gives a little extra directional stability at low speeds - something the Harrier needs since the effect if the intakes is to make it directionally less stable - in fact, unstable. I believe the buzzword is "intake momentum drag" - usual excuse for poor hovering! I'm sure JF will come along and give the real gen.

Now, if you were really sharp you'd have seen another panel behind the nose gear, and between the front edge of the Gunpods - called LIDS and does some whacky aero thingy to give you a bit more VTO (Vertical Take-off) performance.

Airbrake was also used on the GR3 in the Falklands. It had no chaff dispenser, so someone came up with the idea of shoving the chaff behind the airbrake. When the Argie radar lit them up on their RWR, they'd pop the airbrake to drop the chaff. Must have had some clever gizmo to stop it falling out while the airbrake was out until the gear came up...

Hope that helps...

NoD

[WE Branch Fanatic]

Nigel

Thought it was the Sea Harrier that had chaff deployed from the airbrake?

[Impiger]

We used to put chaff in the airbrakes of the F4 as well. Just pop it in an A4 envelope still in its carboard packages as used in the Canberra T17 and hold it in place with a bit of bodge tape (a clever gizmo indeed) until pilot selected in. Nav then pulled airbrake circuit breaker to prevent inadvertent dispensing until what is now called fence - in checks or going sausage side as it was more often called.

[NigelOnDraft]

Thought it was the Sea Harrier that had chaff deployed from the airbrake? Probably was... little difference apart from a grey paint job <G>

NoD

[twang]

I must admit my memory is'nt what it was !, but thought the GR3's had an ALE 40 (Chaff & flare) dispenser fitted in the (lower) electrical bay hatch. It was a particulairly unsafe MOD (in common with the original Sidewinder MOD on the GR3).

[NoHoverstop]

Airbrake was also used on the GR3 in the Falklands. It had no chaff dispenser, so someone came up with the idea of shoving the chaff behind the airbrake. When the Argie radar lit them up on their RWR, they'd pop the airbrake to drop the chaff. Must have had some clever gizmo to stop it falling out while the airbrake was out until the gear came up..

On Harrier Is (don't know about the Harrier II, but probably the same) the airbrake is automatically set partway open when the gear is down. If it was fully open it would interfere with the ground. So it is only (normally) possible to fully open the airbrake when the gear is up. I expect the chaff trick was done with a parcel of chaff, a bit of string and some sort of cunning knot which got pulled un-done when the airbrake was fully open.

Every so often the thing that makes the airbrake open to an intermediate position when the gear is down gets carried away and fully opens the airbrake. Some time later, the runway sweepers retrieve the ground-off bits of airbrake lip and present them to the pilot. Or at least that's what used to happen.