Airfix 1/48 Walrus question

[One 48]

I bought this from Delta7 here on the sale forum last week (good trader BTW) Always wanted a good Walrus and this seems to be the kit I've been waiting for, especially for my new focus scale of 1/48

Poured over the instructions this morning with a view to clearing the bench and making a start ... and noticed the engine seems to have it pointed at a slight angle from the fuselage, from side view (that I understand) but it was the top and bottom engine view thrust line deviance that caught my attention ... I doubt Airfix have made a mistake here, it must be as it was ... so my question is, why would the rear facing propeller engine thrust line not be that same as the fuselage as viewed from above or below? Is it because of the engine torque?  Walrus engine cant have been that powerful of an engine though, compared to say a P-47 and others and I don't think I've noticed any deviance of alignment in those or anything else really? If there is it must be minuscule in 1/48 ... unless the Airfix paint guide is exaggerated for effect ... perhaps to show its not meant to be in direct alignment with the fuselage ???

Its a 4 blade prop too if that has anything to do with it?

Is it because its a biplane with an unusual aft pointing engine under the wings configuration perhaps? I'm no aeronautical Engineer obviously

Its quite noticeable in the Airfix colour call out sheet ... I wonder why its like that?

Good that Model building can arouse the curiosity of the real subject at times, one of the things I like about this hobby.

Hope someone knows, awesome looking kit though, it really is.

[dogsbody]

Some drawings from Mushroom Model Magazine Special Yellow Series: Supermarine Walrus and Stranraer.

 

 

 

 

 

 

Chris

[Simon]

From Wiki:

 

"The engine was offset by three degrees to starboard, to counter any tendency of the aircraft to yaw, due to unequal forces on the rudder caused by the vortex from the propeller."

 

and from here:

 

"I thought that the engine and propeller was a bit offline so when the very helpful bloke came back I asked him if I was seeing things and he told me that my eyesight was OK and that the engine is mounted 3 degrees off line because when the engine is running the back wash blows against the tail plane and rudder and causes the plane to yaw. This made taking off difficult when the plane was taking off from the water. So the 3 degrees offset countered this."

 

Cheers

 

Simon

[Stevejj]

Was still a cow to fly though I believe. I did read it was quite unstable, but I can't find the book its in !!!

[Work In Progress]

1 hour ago, One 48 said:

my question is, why would the rear facing propeller engine thrust line not be that same as the fuselage as viewed from above or below? Is it because of the engine torque?  Walrus engine cant have been that powerful of an engine though, compared to say a P-47 and others and I don't think I've noticed any deviance of alignment in those or anything else really?

If you put a massive whirly thing on an aeroplane that whirls only one way, you effectively make the aeroplane asymmetric when you put power on. So there are various things you can do to help the pilot, and adjusting the thrustline is a common one. Real question is why didn't everything else do it? Part of the answer is long in-line engines like the Kestrel and Merlin and other hot-water twelves where dramatic changes in the thrustline are difficult because of the form factor. 

 

On the radial Hellcat and Bearcat though you will note significant downthrust, and on the Chipmunk, oddly, the engine is set up with a midge of sidethrust the wrong way, i.e. to make the swing worse, better to train pilots who were (at the time of the original design) expected to move onto more powerful taildraggers to expect to have to use a lot of rudder on take-off and with power changes generally.

 

Another trick often used is offset fins, as on a lot of Hawkers, and the Macchi MC.202 and 205 even had one wing longer than the other. 

 

Incidentally while the Walrus is a draggy old thing it is not short of power. 750 hp in an aeroplane that weighs less than 5000 lb empty is really quite a lot, enough to required a significant degree of respect in handling the beast. The P-47D has 2000 hp but it's twice the empty weight.

Edited January 27, 2020 by Work In Progress

[One 48]

Thanks Guys, all your answers make a lot of sense, while I was away went looking for an Aircraft home build video series by Mark Evans, from my past I remembered, this explains this well too, have a look at this vid from time of capture, it explains it all quite well too.

The Walrus thrust deviation does seem to be more deviated than most Aircraft though ... interesting stuff, TY All.

Interesting stuff.
 

 

[One 48]

After watching Marks Video and reading explanations here too, I think the more than usual exaggerated deflection of the Walrus's engine thrust was because of its more than usual aft position and closeness to the vertical rudder ... Its all making sense now.

👍

[One 48]

2 hours ago, Simon said:

From Wiki:

 

"The engine was offset by three degrees to starboard, to counter any tendency of the aircraft to yaw, due to unequal forces on the rudder caused by the vortex from the propeller."

 

and from here:

 

"I thought that the engine and propeller was a bit offline so when the very helpful bloke came back I asked him if I was seeing things and he told me that my eyesight was OK and that the engine is mounted 3 degrees off line because when the engine is running the back wash blows against the tail plane and rudder and causes the plane to yaw. This made taking off difficult when the plane was taking off from the water. So the 3 degrees offset countered this."

 

Cheers

 

Simon

Great post Simon, just read your links.

This pic really shows it