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BAe-146 - Tail Spoiler on Finals?

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BAe-146 - Tail Spoiler on Finals?

Old 16th Nov 2008, 22:27
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BAe-146 - Tail Spoiler on Finals?

Question concerning the BAe-146/Avro RJ.

I've seen many landings of the BAe-146, both on YouTube and from watching them land at my local airport (Galway, Ireland).

When exactly does the "lift dumper" speed-brake on the tail extend? Is it automatic, or pilot activated? Is it separate from the speed-brakes on the wings? Is it difficult to fly when extended?

Thanks in advance,

Aaron.
TheCosmicFrog is offline  
Old 16th Nov 2008, 22:36
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It is a speed brake, manually deployed by the pilot, at will, and it is available to be used at any speed. It is usually selected some 100 - 200' above threshold before touchdown. It is not a lift spoiler, and it is not generally used in normal flight.

Lift spoilers are in the upper surface of the wing, 2 of which deploy automatically when weight on wheels logic detects contact with terra firma, and a further 6 are deployed by the pilot after landing.

And before you ask, no, there is no reverse thrust, just the aerodynamic bits I've described to assist the wheel brakes, to achieve the short landing performance which the BAe146 is known for.

I hope this helps.
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Old 16th Nov 2008, 22:37
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It's been a while, but.

The speed brake is extended by the pilot on short final, usually about 50' or so.

The 146/RJ doesn't have speed brakes on the wings. It has spoilers for roll control in flight and lift dumpers on landing, but they don't extend airborne for speed braking.

Not difficult to fly with the speed brake extended.

The 146 speed brake is very effective as a speed brake, far more so than the spoilers on a B717.
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Old 17th Nov 2008, 06:13
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Pilot Mike there are only 6 lift spoilers in total and 2 roll spoilers.....albeit the 2 outboard lift spoilers are mechanically linked...and deploy only with the speed brake (airbrake) handle fully back and aircraft on ground. (same handle operates the airbrake at the rear and then the lift spoilers.
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Old 17th Nov 2008, 10:29
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Apologies for including the 2 outboard roll spoilers with the 6 lift spoilers. Thank goodness the trusty engineers remember the systems better than the rest of us!
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Old 17th Nov 2008, 20:16
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Thanks guys.

It's remarkable how quickly a BAe-146 can stop without thrust reversers!
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Old 17th Nov 2008, 20:21
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Originally Posted by pilotmike View Post
It is a speed brake, manually deployed by the pilot, at will, and it is available to be used at any speed. It is usually selected some 100 - 200' above threshold before touchdown. It is not a lift spoiler, and it is not generally used in normal flight.
It's different on the approach to London City, with the 5.5 degree approach. There the speed brakes are deployed as soon as the aircraft is stabilised on final descent. If you are in Central London and LCY is on runway 10, you can look up and see them open up with about 5 miles to go. And in the cabin you can feel it .....

Some may remember that when Prince Andrew/Fergie got married they left for their honeymon in an RAF 146. As it turned away from the terminal for departure, and in front of all the TV cameras, the crew opened up the speed brakes, and they had a "Just Married" banner hanging from the inside of the mechanism. In idle moments I wondered if they got airborne with it still there.
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Old 17th Nov 2008, 20:21
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They are quite often left extended when the Aircraft is on stand. Why is that?
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Old 17th Nov 2008, 20:22
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well I guess it dont go too fast!!!!!
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Old 17th Nov 2008, 20:24
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F-28 also had the speed brake on the tail. An absolutely wonderful piece of kit. 320kts till 7 mile final kept the interest up!
Lift Dumpers as well, they were deployed after touchdown - mostly!

I think the SB's being left open on the ground on the RJ/146 was for APU cooling??
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Old 17th Nov 2008, 20:36
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Polarbearjim

The Airbrake is operated hydraulically. There is a tiny clip that's meant to keep the halves together when the pressure falls but it rarely works.

Therefore as pressure reaches zero the airbrake halves are free to move, and move they do.
 
Old 17th Nov 2008, 21:33
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As mentioned, they're often left open in high ambient climates to facilitate APU bay cooling. High sensed APU bay temp = APU over heat = APU shutdown.
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Old 19th Nov 2008, 15:42
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Ad-astra,

Grateful for any correction but my understanding is that the petal airbrake on the F28/F70/F100 is all or nothing, whereas the 146/ARJ one is variable; a claimed advantage for speed control by the men of Hatfield, although the sticky throttle boxes on the early 146's was probably more relevant. It's also one of the system differences between the 146 & ARJ. On the 146 the lift spoilers were manually activated by pulling the airbrake handle back through a detent released by the WoW system. The Avro introduced an autospoiler function, although SOP was still to crank back the handle for the day the automatic's failed.

Interestingly the same men of Hatfield also claimed genealogy from the Bucc. rather than Fokker (naturally!). Those operating onto the East London aircraft carrier may see the resemblance.
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Old 19th Nov 2008, 22:21
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The F-28 speed Brake was variable and whilst the Fix-it lever could be pulled at any speed the actual deflection of the Speed Brake doors was proportional to the speed of the Aircraft - around 200Kts springs to mind where the Brakes were fully deployed.
Alas I didn't fly the F70/F100 - a curse I will have to live with! I have heard that they did have the all or nothing feature but that information has been spoiled by alcohol and time.
Lift Dumpers were actuated via a combination of wheel speed generators and micro switches on the mains after touchdown but once again we were able to prove anything is possible if we try hard enough as we had the Lift Dumpers deploy in flight on one occassion. Mr Fokker wasn't pleased!
A wonderful aircraft ahead of its time.
If only Mr Boeing could realise that generators donít need to be put on line after start, that anti ice systems can operate automatically, speed brakes can actually slow an aircraft down and an aircraft does not have to fly like a D9 bulldozer

Once again a curse I will have to live with!
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