1/32 Scratch Build Parnall Peto

Evening All,

The subject of my next project is the Parnall Peto floatplane. What I hear you ask? I too was a little baffled when a fellow modeller asked if I would build one for him in 1/32 scale. He had seen my Short S 38/HMS Africa model and it reminded him of an experiment carried out by the Royal Navy in the mid-1920's with aircraft carried by submarines. Briefly the Royal Navy had 18 very large (K class), submarines built during WW1; three others were completed as M class vessels. The original M class had a 12 inch (305mm) cannon mounted on the fore deck but after M1 was lost in an accident in 1925 the other two were withdrawn from service, the cannons removed and replaced by a hangar. The Parnall Peto floatplane was designed to be put into the hangar and launched from a hydraulic catapault so that the submarine had an independent aerial observatory. Experiments were successfully carried out but sadly M2 sank with the loss of all hands in 1932 and the project was subsequently abandoned.

My modelling friend wants to build the foredeck and catapault of the submarine and will make a sea base for it: I am to build the floatplane which will be mounted on the catapault, so I am being dragged well outside of my comfort zone to build an aircraft which flew at least 10 years after the time period of my usual subjects for modelling! I have found some drawings which I have scaled to 1/32 and have made a slow start to building one of the two Peto aircraft using the usual scratch building materials: plastic sheet, strip and rod, basswood and brass rod. I have been given an old radial engine and a seat to help with my part of the build.

I started by laminating two sheets of 80 thou card for the wings:

The strange markings on the plastic were where my friend's children had been playing with printing stamps - the inks were later removed in the filing/sanding processes of shaping the wing profiles. When the profiles had been shaped I added the ribs from 10 x 30 thou strip which was sanded and then covered in Mr Surfacer and smoothed off. The ailerons were scored with a knife and one has already been cut with a razor saw for re-attachment later. I have also cut and shaped the tail surfaces from 40 thou card:

The rear fuselage was made from 30 thou card for the sides and bottom with 40 thou formers added. The upper rear decking consisted of flat surfaces and will be added later from plastic card cut into strips:

Before I cemented the sides to the bulkheads and bottom I ran the rear sections between the blade of a pair of scissors and my thumb to make the plastic curl so it better fitted to the curved fuselage bottom. The nose of the Peto consisted of a support for the upper wing and a semi monocoque front end which I inted to file to shape from basswood. A block of basswood was found and filed to slide beteen the forward fuselage sides, and some of the facets of the front were marked on to the wood:

The engine was a 5 cylinder radial which was in a cowling at the front of the fuselage: I glued two pieces of basswodd to make a suitable block which can be filed to shape:

I have cut the facets of the front fuselage basswood block and marked the shape of the front and rear of the cowling for the engine so that I can file and sand the pieces to their final shapes:

I will add cockpit details before I fix the front fuselage wood permanently, so some modellers licence and imagination will be necessary to construct a plausible pair of cockpit interiors as I cannot find any information on the interior of this aircraft.

Thanks for looking.

Stevef.

Evening All,

The lower wing half from which I unintentionally removed the non-existent aileron has been totally replaced as I could not make a decent repair: the two sections just would not align properly so I took the easy route and started again. I drilled holes in the centre section and ends of the upper wing halves and inserted brass pins so that when the parts were joined I could get the correct dihedral and still have a strong joint:

The wing sections were secured with super-glue for the brass pins and cement for the plastic: the wings were jigged with scrap plastic to ensure the correct angle of dihedral:

The joints were filled and sanded smooth so now I have usable wing sections:

I have still to shape and fit the ailerons to the upper wing - holes will be drilled and brass pins used again to strengthen the joints when I do fit them.

I have been working on the upper fuselage section that held the cockpit openings. This section had flat sides and top which I decided to mould. I made a male former from basswood and a female from plywood:

My initial attempts to make a moulding failed for two reasons: first the male mould was slightly too small so that the new part did not fit on to the fuselage without leaving gaps which were too conspicuous to hide. I made a completely new male mould and tried several times before I realised that instead of using 30 thou card I needed something thicker as the mould was drawing out the plastic and still leaving gaps. When I used 60 thou card and enlarged the female mould slightly the problem was solved:

Holes were cut and shaped for the pilot's and navigator's cockpits:

and the part tested on the fuselage:

When it is properly cut to size and sanded it will make a good fit. Having placed the new part on to the fuselage it is clear that very little of the interior will be visible so I have made two seats and will add very few extra details, except seat belts and possibly a control column:

The seats were made from plastic sheet and were based on photographs of aircraft seats from the period: I have no specific details of what they were really like and as they will hardly be seen, it does not matter too much.

 

The floats were shaped from basswood following a simple and straightforward method which I use for all of the parts which I shape from wood or laminated plastic. I started by cutting two pieces from a larger block of basswood which were slightly longer and wider than the finished floats. I marked one of the blocks with lines 1 cm apart so that I could transfer the plan of the float to the top surface, and the side elevation to the sides:

I cut much of the excess wood from the bottom of the block to leave the side elevation visible: the upper surface of the block will be the top of the finished float:

A saw-cut was made where the float step would be and the bottom of the float was shaped with a wood file. When I was close to making the step on the underside of the float I deliberately removed wood from the rear of the step so that I could file the rear of the float flat without taking off wood from the front end:

I could draw lines across the flat bottom of the float by using the lines on the side as guides. Now it was possible to draw the plan of the float on the bottom surface:

That was necessary because the sides of the block had to be filed away to get the correct width of the float. Before filing started much of the excess wood at the front and rear ends had been removed with a saw:

The bottom of the floats were shaped like the bow of a speedboat at the front end, but were flat surfaces on either side of a keel in the centre and rear. The keel line was drawn along the centre of the underside of the float, and lines were drawn on the sides of the block to represent the edges of the float sides: the keel line and lines on the lower sides of the floats were used to guide the filing of the flat undersides of the float.

I now had a block of wood with flat surfaces. To achieve the concave curve at the front end of the floats I used a half-round file, and glasspaper wrapped around a round file to gently and slowly remove the wood to the desired shape. A centre line was drawn on the upper surface before the curved upper sides of the float were shaped with a file. I used card templates to ensure that the correct shape was made.

The upper float in the image shows the curved upper surface, and the lower float the concave nose, flat rear and step on the underside.

Thanks for looking.

Stevef.