View Full Version : Reversing props

17th Apr 2003, 08:31
Is propeller reverse possible in-flight?
I understand that its not normal, but it seems like Ive heard of it in some cases. What installations, if so. Thanks

Diamond 'katana' geezer
17th Apr 2003, 08:39
It certainly is!
I think (please correct me if i'm wrong) the Andover had the ability to reverse it's props whilst still in the air.
It was used a few feet above the ground on the landing run to shorten the ground roll.

On the other hand, there has been a few jets that have had reversers engage in-flight. has this ever happened to props?

17th Apr 2003, 08:53
Thanks katana for the very quick reply.

Is reverse ever intentionally used in the descent, such as speedbrakes on jets?

17th Apr 2003, 09:00
In most airplanes, reverse is not available inflight, unless the safety interlocks somehow fail. Some turboprops have a "flat pitch" setting where zero thrust is produced, and the propellor blades act as speedbrakes.

HOWEVER, the C-130 used for aircraft carrier trials on the USS Forrestal several years back had the ground interlocks removed so reverse pitch could be selected just BEFORE touchdown.

17th Apr 2003, 09:10
A mate of mine that flew MU-2's was curious about this, and since the flight manual didn't say you couldn't do it, he decided to give it a try one day.
He did it when very high on finals once, and he said that "the wing stopped working and the plane just dropped out of the sky!!!!".

So he never did it again.

17th Apr 2003, 12:09
The DHC-6 , Twin Otter, has reverse available in flight, but is not used, for safety reasons, we do use discing(in flight), which is what happens when the blade pitch angle is flat(fine pitch),this increases drag, which can help to on a semi high approach, with out the increasing airspeed from pushing the nose over to salvage the approach.

17th Apr 2003, 14:06
Had a demo flight with a DH pilot years ago (1966) in a twin otter, he crossed the runway threshold at 1500agl with the props in reverse and full flaps, and landed and rolled out in less than 1000 feet.
Quite spectacular performance...:ooh:

17th Apr 2003, 14:11
18 W, let me assure you that reverse in an MU-2 in flight etc, for that matter any Garrett powered turbo prop is not permitted. The approved FM for the aircraft states this as does the Garrett manual.
Lucky chappie!

17th Apr 2003, 20:15
I can confirm that, in the Andover C Mk 1, you select reverse during the flare for a short landing. Reverse is selected using the same lever that removes the Flight Fine Pitch Stop after a normal landing (same lever as in the HS748) by pulling it further out and back. It is a "T" handle in between and slightly aft of the throttles. One of the problems is that you need to have your hand on the nosewheel steering tiller when reverse is selected (or when the FFPS stops are removed) in case only one prop goes into reverse! Therefore, careful co-ordination is required between the 2 pilots as the controls must be restrained also during the landing rollout. There is more than one way of doing this. One SOP was for PF to initiate the flare, call "your controls", after which PNF handled the yoke for the remainder of the flare and touchdown, and simultaneously put one hand on the NWS tiller and selected reverse thrust with the other. I was a passenger during one such landing where PF (the Squadron boss) flared too high, called "Your controls" and selected reverse at about 10-20 feet! PNF (the flight commander) afterwards said that he did not know whether to push, pull or reply "Negative, your controls!" After the very spectacular arrival, the cheer from about 20 Andover qualified pilots down the back was VERY loud! We then changed the SOP such that PF kept control of the yoke and tiller and PNF selected reverse on PFs call.

I believe that the PC6 uses reverse in flight to achieve steep descents and that Concorde can also (although it creates a lot of buffet). Can anyone confirm this?

17th Apr 2003, 20:32
A captain on a SF34 once did, even though it is not permitted. Net result was turbine parts out the exhaust and a very rough landing in a corn field.


18th Apr 2003, 01:27
Movie of C-130 Carrier Landing (http://www.airspacemag.com/ASM/Web/Site/QT/HercOn.html)

Bonus to anybody who can spot the blades going into reverse;)

18th Apr 2003, 03:08

Recently there have been several things I don't believe. To this list must be added "my own eyes".

18th Apr 2003, 04:23

If you look closely, you can see the difference in the look of the props (a bit more vapor?) just as he crosses the rounddown.

compressor stall
19th Apr 2003, 15:25
The PC6 has an increible ability to descend with the engine in BETA 6000 feet per minute without the airspeed over 90 knots.

I seem to recall talking to one of the PPRune Mods about this a couple of years back - he used to para drop in them. Could have been Rob? :confused:

Re the herc above...would it not be doing as the jets do and land concurrent with the application of full power in the case of a missed hook?

19th Apr 2003, 20:16
I was involved in an air search for survivors of an Indonesian C-130 that crashed into Victoria Harbour, Hong Kong, shortly after taking off from Kai Tak one Friday night in the mid 1990s.

I understand that the pitch control of one of the starboard props was lost. It went into either flat or reverse pitch, yawing and rolling the aircraft hard right until it hit the sea, where it broke up into small pieces.

Fortunately, the runway was 13; if 31 had been in use the aircraft would probably have crashed onto the apron or main terminal building.

20th Apr 2003, 00:05
Interesting comment Shy Torque, I lost two very good friends in a very similar situation with the first production model of the Guppy 201 at KEDW in the late sixtys, outboard prop went into reverse just after liftoff, aircraft promptly rolled over and crashed.
Largest pieces remaining were the engines...nasty business.
An uncontrollable prop is BAD news.

Captain Stable
20th Apr 2003, 17:54
cs, you're entirely correct.

The skydivers used to hate losing the spot above cloud - 'cos in the descent they tended to join us in the front.

You could climb to FL100, chuck a load out, descend, land, take on another load, and in the climb on the way up cross the previous load still coming down.

Flight Detent
20th Apr 2003, 19:20
Hi all,
The P3 Orion, with similar engine/gearbox setup to the C-130, it's just the gearbox that's upside down on the Herc, CAN be selected into reverse in flight, although you can't do it unintentionally!
The prop low pitch stop can be overcome by selecting the ground range with the power levers (the P3 does not have the ground/flight selector like the Herc, it's done automatically, when ground range is selected.)

The catch is, that to select ground range is very difficult, physically, to overcome the power levers' solenoid controlled stops, which are in place when the aircraft is airborne, but it can be done!
Very dangerous to try though, with big props and a stubby wing, it would drop like a stone.
Also, the P3 does not have anti-skid brakes, pity.