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.

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.

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

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

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.

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'!

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.

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.

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/

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.

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

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.

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.

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.

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

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.

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

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!

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

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:

DaveRUK
Thanks for your input. I totally agree that the AB book may have some unintentional errors, bearing in mind that many Fleet Air Arm records were destroyed during the early 1950's. I just looked either side of the "possibly destroyed" aircraft to get an idea as to when they had been built and reckoned that the construction dates of some of the "possible" aircraft were post 4/5 May. X9558 was one of my suspect aircraft....
It would be nice if there was a Saunders-Roe archive somewhere!
Atb
Andy

Ahem er . .
If half the pair of props was right and the other half wrong you might have a case that the reversed one only delivered half normal thrust so 75% of expected net thrust would be more like it.

True, but that isn't what was suggested. The post I was responding to suggested that it was probably one RH-rotation prop and one LH-rotation prop, with the latter therefore rotating "backwards". In this situation the RH prop would develop full thrust while the other would develop ~50% thrust in the opposite direction, giving a total of 25% of the *expected* thrust.

If you had two identical RH props with one being fitted backwards then your total thrust would be in the region of ~75% of the expected value (for any given throttle setting), but while I suspect that may be what actually happened it wasn't the scenario I was responding to.

OTOH if you had one RH prop fitted correctly, and a LH prop fitted back-to-front (so that it could rotate "forwards") bothg props would produce 100% of the expected thrust but in opposite directions, giving a net thrust of zero*

PDR

* Except that they wouldn't - the rearmost prop would probably produce slightly less thrust due to operating in the wash of the prop in front of it (the amount of reduction depending largely on the rotational speed and the solidity of the props) so there would be a (very) small net positive thrust

PRD1
That post you were responding to was so confused it seems to have confused me as well. Once it introduced the total red herring of fitting a Tractor prop to a Pusher installation I more or less gave up, as what this started from was simple incorrect assembly of correct props.

Well indeed. But I think I got what he was saying, in which case my response was correct. But it's possible that I didn't get what he was saying, in which case my response was incorrect. I think.

Nurse - I think it's past time for my blue pill...

PDR

Wrong way round prop
 

Taken from my original source:
"It was later found that one half of the four-bladed propeller had been assembled in reverse and was unnoticed at final inspection"
Does that make it any clearer....

As I told before it IS confusing. Not only because of tractor and pusher engines, with pushers that are Yes or not modified to run in an opposite direction, with "normal" and pusher props. Add to it that English engines run the "wrong" :) direction as opposed to US types and we have a Babylonian confusion!

But OK having half of the blades installed wrong, is quite an achievement from Murphy... AND no one noticed....
Luckily we are some 75 years further and comparable mistakes like this are not made any more :( :( :( :(

You might like to read this......
Variable Pitch at the Cradle of Aviation Museum

Regretably as late as the 1980s someone still managed to fit a helicopter individual tail rotor blade the wrong way round, so the trailing edge was wrongly facing the rotational airflow. The remaining blades were fortunately the right way round. The pilots were alert to the extra vibration during ground taxi before getting airborne and it didn't lead to disaster (I think). All it needed at design phase was different retaining bolt diameters; rather than the ineffective outboard/inboard label. Murphy's Law.

New one on me.....

SARO had a factory on what is now Weybridge Trading Estate/Business Park and flew completed aircraft from nearby Chertsey Meads.

Chertsey Meads - UK Airfield Guide

CFM Shadow
 

During my short time as a Microlight Inspector I was asked to do the annual on a Shadow microlight.
Airframe checked, now for the engine. A pusher 2 stroke with a multi bladed prop.
I cracked up laughing and had to walk away, thinking this is a send up!
Was it a test on me? Very tempted to ask the owner to taxy it for but he might overheat the motor. Yep, all the blades on backwards! He assured me it flew alright!
Had a look round his hangar, no clue so asked to see the actual prop he had been using. Then he produced the unapproved one he had been using with all the moans about the approved prop being poor etc.
Oh dear.
SFD