Scale Soaring UK

I have just received a very old model of a Slingsby Sky. It is in RAF colours and seems to be modelled on one of the gliders that competed in world championships in the early 1950's.

The model is believed to have been built in the 1980's.

Does anyone recognise the model and the designer? Seeing Brian's rebuild of the EoN Olympia, I thought it might be a John Watkins design?

If anyone has any thoughts, please let me know. Many thanks
Mike

Hi Brian

No, I have not had much success in finding out who the designer was. I was hoping that Roger from Sutton Bank may have some ideas. He has a good nose for these things, but nothing yet.

The airframe does look in very good condition. It seems to be covered in a lightweight fabric with a applied paint/dope finish. the RAF roundels seem to be waterslide and the competition numbers and glider code are cut from vinyl, or similar.

The DFS airbrakes are driven by a single servo mounted between the fuselage wing root formers. The push rods were very bent probably due to the wings being stored at some time by standing them on their wing roots.

There is some minor surface damage to the fuselage paint surface here and there, but I have seen worse on full size vintage machines.

If anyone has thought on the source plan or designer please chip in.

A few more photos....

Mike F

Sorry Mike I’m not sure of your Sky’s origins. You’re right that John Watkins made a lovely model of the Sky but I think that was 1:3.5 scale and in the 1990s. Other than Chris Williams, the only other UK scale model glider designers from the 80s that I know produced plans were Mike Smart and Keith Humber. But i never heard of either of them making a Sky.

The model looks lovely by the way and I expect would fly slowly on that scale-like wing section. Just noticed the twin horns on each aileron...very scale! The full size has split ailerons because they are so long. Your builder had an eye for detail.

If you need any photos of full size Sky’s just ask - I have dozens! There are usually at least 2 at the annual Slingsby Vintage Glider weeks held at Sutton Bank every August. It has lovely proportions although a relatively short nose for the long tail moment, so the tail end needs weight-watching .

Rog
P.s. drove past your neck of the woods yesterday on our way down to Cornwall.

Hi Roger

So no further on with the designer. The model Sky could have been developed from a Gull IV plan since they have similar proportions with stretched fuselage and greater wingspan.

I will try to find out more about the builder, I believe he was a local guy, perhaps there are fellow fliers that are still active.

The model very well replicates one of the competition Skys. I found a photo of one on www.all-aero.com. This is the only ref that I can find to one in RAF colours is XA876. I think that the builder of this model may have guessed at the Code since it is vague on the photo; choosing a figure 9 rather that 8. The reference XA876 is the only on on R Cawsey's Sky listing, but his list is incomplete.

Cliff, thanks for the link to Jim's drawings. They do not tie up with the structure of this model, but Jim's wing design would make for a nice flying model.

I'll continue to tidy up the airframe and fit it out with up new gear.



Regards

Mike

Hi All,

Any idea what the logo on the nose is? I will try contacting the Vintage guys at Lasham.

Regards
Mike

Hi Mike, if your model was built off my fathers plan then it has been modified. The wing root / section certainly looks different as does the wing retention system.

A few more close ups...

Hi Paul

Thanks for sending details of John's Sky. As you say the wing and tailplane connection details are quite different as is the servo gear installation.

I recently assembled the model and tested the flying surface movement. Rudder, elevator and brakes all functioned well, but the ailerons had what I feel to be quite limited movement; about 13mm up and 9mm down measured at the inner end of the ailerons, what do you think?

Flying weight looks as if it will be between 6 and 6.5kg.

I think that with a clean up and some minor filling retouching of paint on the fus, she'll be ready to go. I think I will also install an aerotow hitch in the nose.

I would really like to know if anybody has a clue as to the nose art on the B&W photo in one of the post above. I think it is probably the ETPS logo, but can't trace their 1950s version. There isn't so much historical info on the web about this.

Hi Cliff

Thanks for the link to JIm's model drawings. Nicely drawn, but too recent for this particular Sky which I think was built in the late 1990's.

Any comments and additional Sky details gratefully received.

Many thanks to Cliff, Paul and Roger for information provided to date.

Regards
Mike

Mike,
The ETPS logo on my Oly VV400 which was built in 1946 I think uses the attached crest.
If that suits then Vince kindly drew up the graphic & Barry Cole made decals for me some years ago.
He probably still has them on his PC somewhere.
Peter

Hi Peter

What an amazing forum this is!

Yes, I think that the logo you have posted is the same as the one on the B&W photo above.

Thanks for your response.

Regards
Mike

I have



BC

That's good news Barry!

I have sent you an email with details of what I would like.

Many thanks
Mike

I think you have gotten off lightly there Mike. There doesn't seem to be very much to fix before you have a very nice old aeroplane to fly.
Brian.

Mike F wrote: ↑13 Aug 2021, 10:06 That's good news Barry!

I have sent you an email with details of what I would like.

Many thanks
Mike

Working on it...



BC

Hi Brian

Yes Brian, compared with your full restoration mine is a light refreshment.

I have spent most of my time researching the past life of XA876 and trying to find the construction drawing for this 1/4 scale version of it. One or two of my current club members remember one of the earlier owners of the model, but cannot confirm if he built or flew it.

The some jobs I have to do on the airframe are:

Repair some of the joints on the airframe fuselage that have shrunk of moved. the original joints were butt jointed rather than chamfered some gaps and split are appearing. these are mainly around the nose and wing root section of the fus. Some examples are shown below. These will be repaired using a filler on the exterior and a fillet of epoxy and micro-balloons on the inside. The fus is large enough for me to get access to the joints that need repair.

On one of the wings, which I think may be covered in light weight nylon, the fabric is lifting along the aileron mounting spar (rear spar). I don't know the paint type used but may try some PVA gentle heat reseal this area. it's difficult to get a good photo of the problem. There are a few other dings and scuffs that need attending to. I don't want to repaint or recover the model at the moment.

I believe the model is about 30 years old. It certainly looks flown. The structural condition is very good as is the build quality. the split ailerons are activated by a push pull system from a pair of bell cranks, as is the elevator and rudder, all have minimal play.

I will install an aerotow release and add a few other details missing at the moment eg pitot tube assembly, pilot's seat and as you see, Barry will cut some new decals to complete the look.

If anyone knows of 1/4 scale plans for this type I would like to hear from you. The John Watkins and JIm Owens version have been ruled out.

Regards
Mike

Hi Mike. If you sand and fill the cracks on the fuselage they will be very visable and I suspect that you will end up having to repaint the whole fuselage at least. It would be wise to find out what paint has been used so that you dont get a reaction to the new coat of paint over the old. As for the other blemishes I would leave them alone and call it the patina of age.
Brian.

Hi Brian

Yes, I agree with you regarding the paint. I will, eventually, try a few solvents on the skid to see which, if any react with the paint. also, since access to the interior is good, I may fully line the fuselage from wing root forward with glass cloth and epoxy, rather than applying an epoxy/micro balloons fillet. If it works well I may leave the external finish until the model has been flown.

To get a bit more aileron movement I need to remove some material from the aluminium aileron horns, this will give a little more aileron rotation. At full, but limited deflection, the horns foul on the rear wing spar. I think I can do this without removing the ailerons. At least I hope so because I can't see the hinges at all.

Mike

Hi Brian

Yes, I agree with you regarding the paint. I will, eventually, try a few solvents on the skid to see which, if any react with the paint. also, since access to the interior is good, I may fully line the fuselage from wing root forward with glass cloth and epoxy, rather than applying an epoxy/micro balloons fillet. If it works well I may leave the external finish until the model has been flown.

To get a bit more aileron movement I need to remove some material from the aluminium aileron horns, this will give a little more aileron rotation. At full, but limited deflection, the horns foul on the rear wing spar. I think I can do this without removing the ailerons. At least I hope so because I can't see the hinges at all.

Mike

Paul

Thanks for posting the photos of John's Slingsby Sky.

Do you have any information relating to the aileron throws for his model?

Many Thanks
Mike

My attention has turned again to the Slingsby Sky.

Looking for colour matched pain to complete the cosmetic repairs the the fuselage and flying surfaces.

Also, trying to replicate the 1950's cockpit details based on some photos and details from S&G magazine articles.

Progress photo below: