Pitts Special S1 - 1/3 scale

[Herri]

I didn’t read the instructions properly and I should have made a recess for the

little brass tail wheel fastening.

I have done this now. It wasn’t a big job but would have been easier to do without the ply bit already glued on.

The stringers are next. These must have a rounded profile to the outside.
I made this little tool to get it uniform.

I took a piece of scrap ply. Drilled a 6 mm hole through it ( the balsa to sand being 5mm)

I then cut it through and stuck a piece of sandpaper to it.

I took the edges off the stringers first and used the mark I sander.

It worked a treat and probably nothing new to a lot of you.

[Herri]

The former 4a was glued in place first as the stringers join to this.

Here a packing piece needs to be inserted as later the fuselage sides (3.5mm) will join here.

The cross braces need to have a bit sanded out, so that the stringers all fit nicely.

The ends are sanded to achieve 5mm at the tail post.

The whole thing looks like this:

[Herri]

The undercarriage has some cross pieces to solder in,

My wire bending skills obviously leave something to desire, so I found this bit difficult.

I did mange it but was thinking about not publishing these pictures.

Oh well we all have to learn.

The bits are bind together with wire.

Then soldered

The whole thing looks like this.

[Martin Young]

Hello Herri,

This is a very interesting build.

Thanks for sharing it with us.

I am posting this so I can follow along with the progress.

Great work so far.

[Herri]

The blocks, which stop the u/c when they are no longer under load.

(ie. In flight) were glued in. The u/c has to be exactly 349mm from the board.

This was achieved with a couple of strips of balsa, squared up and drilled 5mm for the axles.

I think the pictures explain it.

View from the front

When the glue is dry, the blocks are drilled out and 2 3mm bolts fitted through.

[Herri]

Next some triangular hard wood was stuck in with epoxy between the front formers and the side wall.

The front ply floor was fitted in. I had to make this as there was quite a bit of ply missing in my kit. (2^nd hand)

[Herri]

A bit of metalwork next.

The tail wheel assembly has to be made. Pieces of brass, screws etc are supplied but you have to decide if you want exact scale or something a bit simpler. I went for (relatively) simple.

First of all a bit of measuring and drilling:

This spacer block was made.

This fits at the tail post

The wheel and it’s fixings were soldered together through the main spring.

It’s now ready, so can be put away until needed

[Herri]

A major milestone here;

The fuselage was removed from the building board and turned over.

Its now starting to look like an aeroplane.

I’ve cleaned the area a bit, so quite chuffed today.

[Martyn K]

I think you have glued those u/c legs on the wrong side...

Only kidding - it's looking great.

Martyn

[Herri]

There is still a bit more to do on the u/c.

2 brackets had to be made, which prevent the elastic from slipping.

2 small steel squares were provided.

I first drilled a 5mm hole and then cut half away.

These are soldered onto the legs.

Then a cable is attached which governs the total movement of the u/c.

It stops the u/c spreading out on a bad landing (not that that could happen to me)

I realized here, my joints of the strengtheners to the legs were not quite correct and I should have studied the plan better.

So anyone reading this and attempting the build, study the plan very carefully when bending and soldering the wires.

The small brass bits are my interpretation of the bits which stop the wire going walkabouts.

I admit here to messing up on the first attempt. A thicker wire was provided but I cut it and clamped with the brass bush provided. Then I tried it out and the wire came out of the bush and wouldn’t go back in.

I gave up and used some wire from a closed loop system going around 3 times. I hope this is enough, even for my arrivals.

The whole thing looks like this

I then just wanted to see how the elastic works but didn’t fasten anything. Seems to work in spite of my efforts.

[Herri]

The wing fastener thingy (tech term ) was glued in place. Again I had to make one as in my kit it was missing .

[John Hill 6]

Hi looking very neat. Getting the elastic cord in and at the right tension I found quite hard as I did this as one of the last jobs, in hindsight I should have done it at the stage you are at now, where access is easy. So my recommendation is any setting up you can do now with this the better, I'm still not sure how I managed to do it in the end but I remember it being really difficult to get the elastic through all the right parts and then joining it together.

[Herri]

Thanks for the advice John, I'll bear that in mind.

I cant make up my mind whether to carry on with the fuse now or build the tail feathers.

I'm going to go flying today as the weather is good, so I'll decide tomorrow.

Cheers

Herri

[Herri]

I decided I wanted to something simple now, so I chose the tail feathers.

The main cores were pre-shaped and just needed gluing together.

I used the already mentioned tape method.

[Herri]

The spars on the trailing edges are hard wood and the leading edges balsa.

The ribs are 4mm square and are penciled in on the core, so easy peasy

A bit of wait while the first side dries. Then its turn over and glue the remaining ribs.

There are a few strengthening bits for the tail struts and in the rubber later for the tail wheel and horn.

[Herri]

The edges are trimmed ready for the edge, which is laminated 1.5 mm balsa as done on the wing tips.

I like this method. Its easy to do if you wet the balsa and gives a strong edge which is easy to sand.

The curve on the elevators was quite tight so needs some wetting and gentle persuasion.

The only downside is I suppose, when you like me use aliphatic, you need to leave it alone for 24hrs.

[Herri]

Well its dry and time to finish off.

I first of all cut the hinge slots as it’s something I have had problems in the past.

I set up a small diamond saw in the drill and got the height correct.

It was then just a case of cutting in. The depth was finished off with a hinge knife. At least they are all exactly on the same plane.

The sun is shining here and its 22C, so I decided to sand everything in the garden. Saves clearing up the dust.

I sanded the edges with the MkII sanding tool (see earlier)

[John Hill 6]

Nice idea with the Diamond cutting wheel, i might have to copy that one, as well as the MK1 and MK2 sanding tool.

Where do you live for it to be 22 degrees???????

[Herri]

Posted by John Hill 6 on 22/10/2013 16:06:01:

Nice idea with the Diamond cutting wheel, i might have to copy that one, as well as the MK1 and MK2 sanding tool.

Where do you live for it to be 22 degrees???????

About 300 km east of Harwich.

(Holland)

[Herri]

Seem to be having problems with the site. Its really slow and I have trouble uploading my pictures. Is it me or anyone else?

Last week was the same.

I have now fitted the wing bolts which was just a case of carefully lining up the wing, so it is square to the center line and drilling two pilot holes.

Then the holes were filed out to 8mm and the plastic wing bolt nuts epoxied in.

The wing is screwed from the cockpit, so you wont see these wing bolts later.

[Herri]

Because I lost a piece of 10mm dowel, which was the next job (fastening the front of the wing) I decided to finish off the ailerons as it would be a few days before I could get hold of said dowel.

The ailerons were built but not sanded.

First of all a piece of 1.5mm balsa was fitted to the wings where the ailerons go. This makes sure the ailerons have exactly 1.5mm between them and the wing. (this will be slightly less with covering and paint)

The aileron side edges were then sanded to fit exactly in the wing recess

Next the ailerons were sanded to the profile given in the plan.

[Herri]

I left the trailing edges until the ailerons were actually fitted, this gives me a bit of room to play with should I be a mill or two out.

The hinges are done next. They comprise of 2mm wire and 3mm plastic tube.

The holes were already pre-drilled in the wings so it was a case of lining up and pushing a bit of wire through. I used a small reamer as its very sharp.

The wire hinges were then pushed through the aileron. They were then removed and the hole enlarged to 3mm.

I then lined up the aileron using some balsa scrap to ensure it was even between the top and bottom.

The plastic tubes are then pushed through and epoxied in.

I left the tubes as one piece through the wing and aileron and will cut them when everything has hardened.

[Herri]

Posted twice as it was so slow, it looked like it hadn't done anything 

Herri

 

 

Edited By Herri on 27/10/2013 16:40:14

[John Hill 6]

Hi, yes I have been having problems too, I posted some pictures on the Precedent Stampe 1/4 Scale build thread today and it took me ages.

[Herri]

I now sanded the ailerons to the wing shape while the hinge tubes were still whole and the pins were in.

I then removed the steel pins and cut the tube through with the scalpel.

The packing pieces were removed at the same time.

It was then just a case of sanding a tad away at the tip leading edges so that the ailerons have enough movement.