Slingsby Petrel 3.4 metre designed by Chris Williams

[Peter Garsden]

 

I made another paper template for the tail before first of all adding some triangular pieces to fill in either side of the top rear of the fuselage. I filed a flat on the 6mm square then stuck it on and filed it to shape. The fin of course is wide and will rest on the top surface. You can just see the left piece. I had filed the fuselage round to follow the formers.

 

I then cut out the .8mm ply and steamed it so that it would bend round the highly curved top of the fuselage. Again I clamped it into position until it dries in shape ready for gluing. I left it a little proud at the back so I can file it to shape when it is dry.

 

 

View from the front showing the join. Again no glue here

[Peter Garsden]

 

This photo just shows that to strengthen the tailplane brass rear tube one fills in with scrap balsa.

[Peter Garsden]

Next comes the tailplane to fin fairings, which are going to be a lot easier to attach and fit with the fin off the fuselage.

 

The plan says use lite ply which is so much easier to sand.

 

I used the cut outs for the root ply rib and drew round it onto bits of the lite ply sheet not used by existing parts. I will fit it then grind down the brass tube to fit.

 

 

I used the profiling tool again to trace the curve of the fin. I had glued two pieces of 3mm lite ply together before sanding it away.

[Peter Garsden]

 

It was important that each fairing was lined up properly front to back and that each fairing was in line when viewed from the back and front. After the glue dries I will cut away to allow the rear tailplane wire to move in its axis.

 

 

I photocopied the plan and laid it over the fin then inserted pins for the front and back each side.

[Peter Garsden]

Next job is to attach the Fin. Chris recommends in his instructions that you temporarily attach a piece of scrap at the rear of the cockpit and line the Fin up with that so as to ensure everything keeps straight. I have also tested the All Moving Tailplane to ensure that it moves smoothly in its fairings. I had to adjust it to stop it catching.

 

[Peter Garsden]

I have been doing a bit of repairing to the Spitfire and Alpha Jet following the last PSSA Meeting at the Orme, but now finished so back to the Petrel and the lower rear sheeting.

 

Thankfully this is in 2 halves, as the bend over the bottom of the fuselage would have been a step too far.

 

Again I used paper templates - I just cut up the previous template made for the top of the fuselage. After cutting out it needed a bit of fettling until it would fit the slightly skewed shape. The join is slightly higher up the fuselage than the top piece to stagger the join and aid strength

 

 

Again the kettle without a lid, Marigolds, and a lot of steam eventually led to the ply bending to the right shape.

 

 

A small piece of balsa aids the gluing area of the slim piece of tubing I bought from Hyperflight which will act as a guide for the closed loop rudder wires.

 

 

To force the piece exactly into position required a lot of clamps and masking tape.

 

Needless to say the elevator control rod has been made up and attached to the servo and lined up before I took this step. I used a piece of 5mm outer and 3mm inner carbon rod with bicycle spokes glued into each end and shrink tubing over the top.

Edited October 21, 2022 by Peter Garsden

[MikeQ]

Hello Peter

 

looks like a painful process.  Glad to see you are back on the Petrel.

 

Cheers

 

Mike

[Peter Garsden]

 

Both rear plywood sections now on and closed loop tubes in place. I think that was more difficult than the top piece.

[Peter Garsden]

Next is the most difficult bit - marking holes for the wing joining bar which is a rectangular brass tube. One uses a template taken off the plan and lines it up with the rear of the canopy opening and the plywood join line

 

 

I lined it up carefully and sellotaped it into position. Should have used masking tape which I did for the starboard side. I used a brand new scalpel blade and cut carefully.

[Peter Garsden]

 

The slots for the wing bearers are cut and amazingly they line up with the tailplane, so it is just a case of getting the angle with the tail correct by using an incidence meter. The wing has to sit at positive incidence to the tail at between 1.5 and 2 degrees. First one puts the meter shown here onto the tail and zero it then attach to the wing and measure 1.8 which I settled for as a half way house.

 

[Peter Garsden]

 

What a fiddle this was. I tried to cut the brass box and tube to size without putting the fairing 3mm liteply support in place and, inevitably, it was too short, so I had to make another. Fortunately I had enough left over to do so. The way to do it is to feed it in oversize, the holes having been cut for the tube, and line up the fairing piece, and cyano it into place by pushing one wing on and making sure the ply fairing rib was at the right angle. Then do the same with the other side, more cyano and you end up with the wing fairing structure in the correct position.

 

I then cut the brass box and tube to size, took the wings off, and glued the box and tube to the fuselage and fairing ribs with epoxy, which I syringed into position. The brass is slightly oversize but I will file it back.

 

 

Next job is to fill the gaps either side with curved pieces of 12mm balsa, then finish off with P38.

[Peter Garsden]

I have now filled the gaps in the fairing pieces with some  scrap block balsa. No need to be precious about it.

 

 

Also used a cone drill to open the large holes in the fuselage side for the electrics, and rubber securing bands.

 

Next job is to spread P38 over the top to smooth out the surface and fill in the  holes such as there are. It was  very difficult to fit a piece to fit which was curved in 2 axis.

 

 

Edited November 20, 2022 by Peter Garsden

[Peter Garsden]

Next is a dob of P38 car body filler, rubbed down to smooth.

 

[MikeQ]

Hello Peter.  
 

your getting there.
 

Sure it wont be long before your on to covering and all that.

 

keep up the good work.

 

mike

[Peter Garsden]

Thanks Mike.

 

Next job is to cover the lower fuselage with 1/32" ply. When I first looked at Chris's photos I thought it went on in one piece. WRONG! Chris confirmed, after I really struggled to make it fit, that it goes on in two pieces. So much easier.

 

I found some really good clamps on the internet which worked really well. Also wide masking tape and clamps.

 

I first made a paper template though you could make two - one for each side.

 

 

 

I steamed the ply over the kettle which keeps boiling if you leave the lid open. When it started to bend I strapped up the bend with masking tape to ease the bend. Incredibly one can bend it double. 

 

 

 

This shows only one half glued in position. I split the one piece in two with my band saw.

[Peter Garsden]

 

I thought I would show the system I used to bend the plywood to shape:-

1. Get the kettle to boil but open the lid before it reaches boiling point and it will continue to boil and the thermostat will not click off.
2. Use rubber gloves. Even so the steam makes your fingers hot.
3. Try to bend the plywood and when it is soaked you will feel it give. Don't bend too far or it will split. It gradually bends with the steam which funnels down the piece.
4. Use wide masking tape to hold the bend. Keep bending and moving the masking tape which shouldn't come off as long as you keep the steam under the curve.
5. Bend the plywood over the curve of the fuselage, and tape it/clamp it in position. 
6. Let it dry for a few hours so that it clings to the shape.
7. Glue and tape/clamp it in position and leave to dry

[Peter Garsden]

Thought I would do a little assemble to give me some encouragement 

[Ron Gray]

Nearly there Peter, keep up the good work.

[GrumpyGnome]

You're going to be so proud when it soars away from the hill. And rightly so - good job!

[Peter Garsden]

Thanks chaps. Not an easy build.

 

Anyway the next step is to spread P38 car filler over the joint to give the wings a neat join.

 

 

In an ideal world you wait until it starts to go off then score the join with a Stanley knife. What you don't do is do something else and forget about it then have to cut through dried filler. This is why there is so much white filler where I cut in the wrong place!

 

Edited November 30, 2022 by Peter Garsden

[Ace]

Coming along nicely 👍

[Peter Garsden]

Thanks guys. Am busy preparing to return to work as a child abuse lawyer after a few months off. You are never too old to work. Planning to retire at 70, God willing.

 

Anyway, this afternoon have steamed and bent 2 pieces of 3mm x 6mm spruce to act as Canopy structural rails to be glued to the 3mm end pieces and fortified by 6mm ply gussets - oooh ahhh..... it is easier to bend 2 pieces of 3mm x 6mm than one piece of 6mm square, obviously... then glue them together with 5mm epoxy to hold the bend in position...clever designer this Mr Williams.

 

 

This photo shows them clamped to the side so that they form the same shape as the cockpit but packed out with pieces of 1.5mm ply to account for springing back once released. Actually spruce is easier to bend than balsa surprisingly.

[Ron Gray]

1 hour ago, Peter Garsden said:

then glue them together with 5mm epoxy

Cor, that’s a thick bit of glue 😜

[Peter Garsden]

That glue was so thick Ron, it was like a Mars Bar. Layers and layers LOL.🤣

 

Next step was to make the corner support pieces out of 6mm ply. Lots of sanding using the disc then more 5 MINUTE Epoxy.

 

 

Masking in place to stop it sticking of course.

[Peter Garsden]

Well, nearly Christmas and the workshop is verrrryyy cold.....brr....

 

And I forgot to take pictures of me making the instrument binnacle, which basically a base of 3mm liteply with two ends butt jointed and a piece of 6mm x 3mm spruce glued to the top then a piece of .8mm ply for the front instrument panel.

 

I found a replica Petrel instrument replica on the internet - 

 

 

I had to resize it then print it on photographic glossy paper and attach the instruments to the back then glue the whole thing onto the front after painting it black, and the frame silver. Incidentally silver only shows up over olive green base so that came first in two coats