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-   -   Wrong way round prop (https://www.pprune.org/aviation-history-nostalgia/605577-wrong-way-round-prop.html)

eMACaRe 18th Feb 2018 09:59

Wrong way round prop
 
Hello Forumites
I am researching the crash of a Walrus aircraft which occurred in 1942. Apparently, the aircraft's take-off run was longer than usual and just managed to stagger into the air. Seeing an obstruction ahead, the pilot banked the aircraft. Unfortunately, the aircraft "side-slipped" and crashed, killing the pilot and passenger.
An account written some years later stated that two of the four propeller blades were fitted "the wrong way round". Would that be possible, or even likely, as the aircraft was inspected by a member of the aircraft inspection department before the flight? If they were, what would/could be the effect on the take-off characteristics of the aircraft?
This crash took place at the Saunders-Roe flying ground near Chertsey, Surrey on the 1st July 1942.

PDR1 18th Feb 2018 10:28

It might be technically possible because the Walrus was fitted with two wooden 2-blade props one-in-front-of-the-other, so one of them could be fitted backwards. I'm a little surprised that this scenario wasn't prevented by having an unequal bolt spacing (so the holes only line up when the props are the same way around), and even more surprised that it wasn't spotted by either the installer, the inspector or the pilot on his walkaround inspection. But every now and then the holes in the cheese line up, especially in wartime.

Goldenrivett 18th Feb 2018 10:45


even more surprised that it wasn't spotted by either the installer, the inspector or the pilot
Similarly the Captain's aileron control was cross wired on a plug to an ELAC computer which was missed by the pilots during their controls checks before flight, during peace time.
https://aviation-safety.net/wikibase/wiki.php?id=147094

WHBM 18th Feb 2018 11:19

A feature of the times. Immediately after WW2 Both the Handley Page Hermes and the Avro Tudor prototype airliners crashed departing their factory airfield in early test flights due to reverse control assembly, the former on the type's maiden flight, the latter killing Roy Chadwick, the aircraft's (and the Avro Lancaster bomber) chief designer.

https://aviation-safety.net/database...?id=19451202-0


https://aviation-safety.net/database...?id=19470823-0

DaveReidUK 18th Feb 2018 11:54


Originally Posted by GotTheTshirt (Post 10056987)
On VP props it is possible to install a blade or blades in the incorrect position. Not sure what prop is on the Walrus.

2 x one-piece, two-blade wooden props bolted together, so as a previous poster has said, it could conceivably have been installed back-to-front.

http://www.warbirdsite.com/propwalrus.jpg

As for the effect of installing one that way, I would expect an appreciable reduction in thrust. Although the blade pitch would still be the same, the camber on the aerofoil would obviously be reversed.

Not to be recommended.

chevvron 18th Feb 2018 13:38

Years ago we had an Army Air Corps Squadron based at Farnborough, initially 664 Sqdn but re-numbered to 656 Sqdn. They were equipped with Scouts and Siouxs, changing the Siouxs to Gazelles in the late '70s.
Scenario is a Sioux calls for departure on air test. I watch him start to air taxy to the takeoff point, then another aircraft calls and my attention is diverted. I look back at the AAC hangar and the Sioux had taxied back and shut down.
5 min later a phone call from a very apologetic Sioux pilot.
'Sorry I didn't call you shutting down' (SOP at Farnborough in those days) he says, 'I was a bit annoyed because the stupid RXXX engineers had fitted the rotor blades upside down'!

PDR1 18th Feb 2018 15:06

As a kid building free-flight powered models the early powered test/trimming flights would be with a reversed props. This gave about half-thrust for gentle flying until there was confidence in the trim.

old,not bold 18th Feb 2018 16:03

When the UK regulations were changed in the 1960s to allow private owner's to do more simple maintenance tasks on their aircraft, a 3-day course was run at Cranfield for PPL holders, to teach them how to do it properly.

At the end of the course, all students were invited to pre-flight a single-engine 4-seater, fixed tricycle undercarriage, fixed pitch propeller, I forget what type it was, which had been "prepared" for this exercise. Most of us got most of the visible defects that had been set up, but not one of the 20+ new experts noticed the fact that the propeller was installed back to front, even though we all spent about 20 minutes on the inspection.

Double Back 18th Feb 2018 16:07

Most likely the Walrus was fitted a normal engine, that is, in rotation direction. I looked through many pictures and when looking from the tail to the front, the engine was turning clockwise, which I think was the norm at that time for British engines. That meant You needed a "reverse" or pusher prop on the tractor setup of the Walrus.
Most likely they wrongly (reversely) installed a NORMAL prop....
It IS quite confusing though, I had to take out a normal and a reverse (model airplane) prop to check if I wasn't talking nonsense!

I also stumbled across this picture, OK, it's just a plastic model, but that one must have been one hell of a fast backwards flying "aeroplane"!
https://www.pinterest.co.uk/pin/360710251396858307/

DaveReidUK 18th Feb 2018 17:12

Re the OP's query, a quick scan through the Air-Britain RAF files doesn't make any mention of the accident, though presumably the aircraft was written off if it was fatal.

So, given the date, most likely a Royal Navy Walrus II.

eMACaRe 18th Feb 2018 17:58

Wrong way round prop
 
The AB book on the Fleet Air Arm, by Sturtivant and Burrow lists several aircraft as being destroyed "probably" on the 4/5 May 1942 during the bombing of the Cowes factory. Several aircraft, mainly in the "X" range appeared to me as being built too late to be destroyed on that night.
I then went to the Surrey History Centre at Woking and looked at the Coroners Report on the accident. The identity of the aircraft was stated - X9558, a
Walrus I

ShyTorque 18th Feb 2018 20:12

I know of a certain home built light aircraft where the maximum advertised engine rpm couldn't be achieved during engine break-in.

The engine manufacturer's rep was initially fooled, but eventually discovered that a "pusher" prop had been supplied and incorrectly fitted to the "tractor" engine by mistake....

After that slight issue had been resolved, the same aircraft crashed on its second flight, because the supposed "belt driven" reduction drive box wasn't actually belt driven - it was a gearbox and didn't have any gear oil in it.... despite the clear warnings in the build manual. I was more than a little glad that I'd declined the builder's request to test fly that particular aircraft.

Tailspin Turtle 19th Feb 2018 00:16

Once upon a time, a rich guy bought a Bell Model 47 helicopter and was taught to fly it at the Bell school. He brought it to his instructor a year or so later and complained that it had gotten weak on yaw-control power. A glance at the tail rotor revealed that the blades had been installed backwards after maintenance, so the sharp end (trailing edge) was facing in the direction of rotation. May be apocryphal.

megan 19th Feb 2018 00:43


May be apocryphal
I know personally of a case where this occurred on a Huey. Flew for 70 hours before the reason for the oft complained about high freq vibration was found.

fedex727 19th Feb 2018 05:07

Also happened on a Shawbury Wessex. Tail rotor blades fitted "the correct way". At least until the tail was unfolded...:ugh:

DaveReidUK 19th Feb 2018 07:01


Originally Posted by eMACaRe (Post 10057267)
The AB book on the Fleet Air Arm, by Sturtivant and Burrow lists several aircraft as being destroyed "probably" on the 4/5 May 1942 during the bombing of the Cowes factory. Several aircraft, mainly in the "X" range appeared to me as being built too late to be destroyed on that night.

It's not necessarily a reliable guide, but the last of the X____ series (Wellington ICs X9600 onwards) were delivered between May 1941 and March 1942, so it's not out of the question.

PDR1 19th Feb 2018 07:32


Originally Posted by Double Back (Post 10057190)
.
Most likely they wrongly (reversely) installed a NORMAL prop....
It IS quite confusing though, I had to take out a normal and a reverse (model airplane) prop to check if I wasn't talking nonsense!

Ahem...no!

If you install a prop back-to-front you here a prop still thrusts in the same direction, just less efficiently. If you had one "normal" and one "reverse" prop installed you'd get about 25% net thrust, and a walrus would barely get to a fast trot with that sort of thrust.

PDR

bcgallacher 19th Feb 2018 08:15

It is possible to fit a Fairey Reed metal prop as fitted to Chipmunk Gypsy Majors back to front. How do I know this? - I saw it done!

Tony Mabelis 19th Feb 2018 09:00

I have seen a tail rotor assy on a Bell 206 installed backwards, it took a bit of head scratching when the 'flapping' part of the rigging check allowed the blade to contact the tail boom.
Normally there was at least an inch clearance.
Tony

Cornish Jack 19th Feb 2018 11:50

Tern Hill in the mid/late 60s. Whirlwind 10 had been in service for 'yonks'. One of the instructors (George K??) starting for early sortie. Engaged rotors, 'interesting' airframe antics, swift shutdown. Tail rotor attached in reverse. Thereafter pre-flight check included - Check tail rotor is aerodynamically the same as the tail pylon. :ok:


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