Use of engine reverse in flight
I think anybody who thinks the C-130,and the Andover could select reverse in flight are talking cobblers,as it would lead to an NTS disconnect,and a possible blade hang-up,and off the side you would go.What you can do in the sim.is not applicable to the a/c.Think about it,as soon as the blades go through zero pitch, you lose a large percentage of lift,and tailplane/elevator blanking,and therefore control,and even more in reverse.
For the Andover,in `73 I spent time as co-pilot doing steep approaches at Bedford,possibly up to 10deg,using an MLS for guidance,and I`m certain we used an extra notch of flap for drag,and power to control the flare, reverse only when down,otherwise one would `wheelbarrow`;these were also done later on the 748,-125,and VC-10,as 2- segment approaches,steep initially,then reducing to 3-4deg for obstacle clearance into tac.LSs.
For the Andover,in `73 I spent time as co-pilot doing steep approaches at Bedford,possibly up to 10deg,using an MLS for guidance,and I`m certain we used an extra notch of flap for drag,and power to control the flare, reverse only when down,otherwise one would `wheelbarrow`;these were also done later on the 748,-125,and VC-10,as 2- segment approaches,steep initially,then reducing to 3-4deg for obstacle clearance into tac.LSs.
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Well somebody mentioned the C5 Galaxy using reverse thrust in flight , in the build up to GW1 a C5 crashed after take off at Ramstein with reverse thrust on 1 engine selected.
If you have to use reverse thrust in flight then you either some gucci display pilot , in **** and need to stop quick or just a spacker for selecting it.
who cares
If you have to use reverse thrust in flight then you either some gucci display pilot , in **** and need to stop quick or just a spacker for selecting it.
who cares
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Originally Posted by sycamore
think anybody who thinks the C-130,and the Andover could select reverse in flight are talking cobblers,as it would lead to an NTS disconnect,and a possible blade hang-up,and off the side you would go.What you can do in the sim.is not applicable to the a/c.Think about it,as soon as the blades go through zero pitch, you lose a large percentage of lift,and tailplane/elevator blanking,and therefore control,and even more in reverse.
Should it be done? Different question.
Was it done in the past? Absolutely.
There is no such thing as "NTS disconnect" - perhaps you're confusing the safety coupling with NTS? Regardless, you'd not reach -6000"/lb of torque unless at high speed, so no decoupling would occur.
Blade hang-up is another matter entirely and is unrelated to selecting reverse in flight.
As a semi-related tidbit of near-useuless information, newer models (H3 & up) have "beta lights" letting you know low-pitch stop has retracted and reverse can be selected.
Again, just because it can be done, does not mean it should...
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Inflight reverse thrust
The DC-8 Series 62 and Series 63 both powered by JT3D-7s had inflight reverse thrust capability on the inboard engines.
I first experienced it on an SAS flight to LAX. The sudden roar and deceleration jolted me for a minute. Fortunately, my travelling companion was a former Douglas test pilot who quickly enlightened me.
I first experienced it on an SAS flight to LAX. The sudden roar and deceleration jolted me for a minute. Fortunately, my travelling companion was a former Douglas test pilot who quickly enlightened me.
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Here's the Andover blurb directly from the Pilot's Notes:
4. Short Landing
Note: STOL techniques may be used only as ordered by the Operating Authority.
(a) Technique:
(i) After the pre-landing checks have been completed (Prop Brake to Rev Idle) reduce speed to below 120 knots and select 27° flap.
(ii) Aim to be lined up with the touchdown area with 30° flap selected at VAT plus 15 knots.
(iii) When lined up, continue the approach reducing speed to cross the touchdown point at VAT. It is important that the speed is maintained at not less than the scheduled VAT otherwise the ability to round out will be impaired.
(iv) When near the ground, close the throttles and round-out to fly level, with the wheels just clear of the surface. Select reverse thrust in order to touchdown. Should the aircraft balloon, do not select reverse thrust until re-established close to the ground.
(v) Reverse thrust is usually selected at completion of round-out, but in some circumstances it may be required slightly earlier. The exact point at which to select reverse can only be determined by practice. Note that if selection is made too early a heavy landing will result.
(vi) After touchdown, lower the nosewheel, apply maximum braking and keep straight with nosewheel steering. Reverse thrust should be cancelled when the speed reaches 30 knots, or earlier if forward airflow past the propellers is detected.
4. Short Landing
Note: STOL techniques may be used only as ordered by the Operating Authority.
(a) Technique:
(i) After the pre-landing checks have been completed (Prop Brake to Rev Idle) reduce speed to below 120 knots and select 27° flap.
(ii) Aim to be lined up with the touchdown area with 30° flap selected at VAT plus 15 knots.
(iii) When lined up, continue the approach reducing speed to cross the touchdown point at VAT. It is important that the speed is maintained at not less than the scheduled VAT otherwise the ability to round out will be impaired.
(iv) When near the ground, close the throttles and round-out to fly level, with the wheels just clear of the surface. Select reverse thrust in order to touchdown. Should the aircraft balloon, do not select reverse thrust until re-established close to the ground.
(v) Reverse thrust is usually selected at completion of round-out, but in some circumstances it may be required slightly earlier. The exact point at which to select reverse can only be determined by practice. Note that if selection is made too early a heavy landing will result.
(vi) After touchdown, lower the nosewheel, apply maximum braking and keep straight with nosewheel steering. Reverse thrust should be cancelled when the speed reaches 30 knots, or earlier if forward airflow past the propellers is detected.
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The DC8/JT3 reverse question. Yes, full reverse was available inflight on the inboards although it could only be applied outboard once the landing gear selector was in the down position. A wondrous system of push-rods, cranks and linkages both on the engine and in the throttle quadrant prevented incorrect reverse operation by physically locking the reverse levers.
The reverse logic system (for that is what it was) was on many occasions sufficiently cantankerous during landing to totally prevent reverse thrust operation, which provided a golden opportunity to fully test the antiquated anti-skid system with the feet pushing desperately hard on the brakes as the hand pulled frantically on four reverse levers which refused to budge from idle.
Magic stuff really: it's not like that today. Come to think of it, all the DC8s I flew are now in the knacker's yard so perhaps this would be better posted in the nostalgia section.
The reverse logic system (for that is what it was) was on many occasions sufficiently cantankerous during landing to totally prevent reverse thrust operation, which provided a golden opportunity to fully test the antiquated anti-skid system with the feet pushing desperately hard on the brakes as the hand pulled frantically on four reverse levers which refused to budge from idle.
Magic stuff really: it's not like that today. Come to think of it, all the DC8s I flew are now in the knacker's yard so perhaps this would be better posted in the nostalgia section.
Last edited by XL5; 5th Jul 2008 at 08:14.
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sycamore
The Chitterne Flyer beat me to it.
If you don't believe us its AP101B-0301-15 Part 3 Ch 6 Para 4.
I must confess, though, that I only have 4659 hrs 20 mins on the Andover.
The Chitterne Flyer beat me to it.
If you don't believe us its AP101B-0301-15 Part 3 Ch 6 Para 4.
I must confess, though, that I only have 4659 hrs 20 mins on the Andover.
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Regarding the Forrestal landings the low pitch stops were removed as to reduce the chance of a low pitch stop hang up causing a swerve. Reverse was selected while inflight on the initial landings but this was found not to be required and thus discontinued.
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Originally Posted by FOG
Regarding the Forrestal landings the low pitch stops were removed as to reduce the chance of a low pitch stop hang up causing a swerve.
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Doesn't seem like a good idea to remove them - regardless of LPS retraction concerns (something that's not at all common).
The low-pitch stop is the only thing that prevents the blades from moving into beta range in flight. The list of possible prop malfunctions goes up dramatically w/o the LPS. Additionally, w/o the LPS, NTS would no longer function normally during deceleration increasing the likelihood of overspeed, pitchlock, & fuel topping in a critical phase of flight...
Seems highly unlikely they'd remove one safety feature & effectively disable another that leads to all sorts of additional problems...
The low-pitch stop is the only thing that prevents the blades from moving into beta range in flight. The list of possible prop malfunctions goes up dramatically w/o the LPS. Additionally, w/o the LPS, NTS would no longer function normally during deceleration increasing the likelihood of overspeed, pitchlock, & fuel topping in a critical phase of flight...
Seems highly unlikely they'd remove one safety feature & effectively disable another that leads to all sorts of additional problems...
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Kind of the idea in reducing the swerve. Hitting NTS would induce the swerve at the back of the boat/on deck, LPS hang up, etc.
Fuel topping would not be an issue on reverse and basic pilotage on takeoff. Overspeeding during the landing phase?
The 1st two passes the throttles were up and back over the tail of the boat. That was considered the least risky option.
I’ll take the word of someone who was there and the official debriefs.
Fuel topping would not be an issue on reverse and basic pilotage on takeoff. Overspeeding during the landing phase?
The 1st two passes the throttles were up and back over the tail of the boat. That was considered the least risky option.
I’ll take the word of someone who was there and the official debriefs.
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Inflight Reverse Thrust
Sorry guys, as an ex-mil aviator I couldn't help chipping in. I remember doing 'short field length landings' in Nimrods to practise landing on the PSP surface at Stanley following the Falklands campaign. These were again practised in the mid-late 80s when Kinloss was on 'Bolthole' at Lossiemouth. Reversers were selected and accelerated at approximately 50ft to ensure a 'firm' touchdown with a stopping capability of approximately 1200ft. Two of the occasions were so firm it cost two full sets of mainwheels and a couple of days of heavy landing checks!
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Seem to recall my skipper calling for reverse in a Nimrod while we soared over the road at Gib still very much airborne. We did stop before our feet got wet but not by much. Can't say for sure if the engines actually spooled up before we hit the tarmac.
Last edited by PFMG; 8th Jul 2008 at 14:26. Reason: forgot to mention aircraft type....must be getting old
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Ilyushin Il-62s (CLASSICs for you NATO codename types) also could select it, at least on the inboard engines. It was quite surprising to see them do that on short finals at Heathrow....