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Alsema Sagitta 1:4 scale

Let us all watch your new project progress.
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B Sharp
Posts: 700
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

The under surface of the left wing has now been skinned, the rib capping added the leading edge added. I have also cut the opening for the aileron servo bay.
I suppose I will now have to start on the right hand wing. (Remember – right wing, right wing, right wing!)
Brian. :)
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038b.jpg
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B Sharp
Posts: 700
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

After a bit of a hiatus attending to other non-modelling matters I have finally started on wing #2.

Having glued the ribs to the lower main spar and allowed them to set overnight I felt that something was slightly amiss but I couldn’t quite put my finger on it. Certainly the trailing edge didn’t fit that well. Have a look at the first photo below and see if you can spot the problem. :(

Ok, I must have been wearing my “stupid hat” when I attached the wing ribs. :lol: However it is now put to rights and I have attached the joiner block and some other components. You can see my jig to make sure that the joiner sits exactly vertical.

Brian. :)
Attachments
Can you spot the problem?
Can you spot the problem?
Joiner jig.
Joiner jig.
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B Sharp
Posts: 700
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

It has been a couple of weeks since I last posted but in that time I have completed wing #2 up to the same level as wing #1. Luckily I have been paying attention and it was the right hand wing that was built so I now have a matching pair. I still have to manufacture the ailerons but apart from that they are both ready to cover.
Brian. :)
Attachments
A set of wings.
A set of wings.
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B Sharp
Posts: 700
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

Today was the big day for first full assembly to make sure that the wings are both sitting at the same angle of incidence and that the tailplane is all lined up. It was also the point that the fuselage wing roots were permanently fixed to the side of the fuselage. After a little bit of fettling everything was square and true before locking in place with judicious application of cyano glue. I have to admit that I was happy to see the airframe sitting there in a recognisable shape.
Brian. :)
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Everything lines up!
Everything lines up!
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Cliff Evans
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Joined: 29 Dec 2019, 15:13
Location: Bristol
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Re: Alsema Sagitta 1:4 scale

Post by Cliff Evans »

Very nice Brian.
https://lasercutsailplanes.co.uk
https://patteaklegliders.co.uk
Phill Tadman
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Joined: 18 Aug 2015, 20:38
Location: South Cambs

Re: Alsema Sagitta 1:4 scale

Post by Phill Tadman »

Lovely stuff
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B Sharp
Posts: 700
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

Thanks guys for your kind comments, they are much appreciated.

I have spent a productive afternoon in the workshop today.
The fuselage wing roots have been blocked–in with balsa and then faired to the correct profile with Upol filler. After final sanding they look fine. I have also drilled the holes for the “multiplex” wing joiner system. :) :) :)
The ailerons are being made from trailing edge stock balsa and these have been cut to shape and await carving to the correct profile. The plan shows top hinged ailerons taped onto the back of the foam wing. However from what I can see from photos of the prototype the ailerons have a round leading edge with central hinges – so that’s the way I’m going to go. :)
I have made a start on trimming the canopy glazing to fit the fuselage and the canopy frame. This is a task which always makes me nervous as one wrong cut and the moulding is rubbished. Usually when I have a canopy pulled for me I order two as I am bound to make a hash of my first attempt. In this occasion I only have one moulding to work with so extra vigilance is called for. All the initial cutting looks good and it looks as though the glazing will fit ok. However it will still require a fair bit of judicious trimming before I have an acceptable (for me) fit and finish. :)
Brian. :D
Attachments
The completed fuselage wing roots.
The completed fuselage wing roots.
First fit for the canopy glazing.
First fit for the canopy glazing.
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Peter Balcombe
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Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Alsema Sagitta 1:4 scale

Post by Peter Balcombe »

Looking very good Brian 👍
gait
Posts: 2
Joined: 10 Nov 2019, 11:27
Location: elburg

Re: Alsema Sagitta 1:4 scale

Post by gait »

Hi Brian,
like your lovely work on the Alsema Sagitta! :D You did a good job on this model.
I'm living close to the original airport Teuge, in the Netherlands, where they used to build this lovely glider.
I'd like to build the plane myself and your postings helps a lot to understand the way Vic had designed and build the plane.
I got a copy of the plane in my hands via traplet publications and this plan doesn't show a buildup ribbed plan of the wing. It shows a foam core wing.

Did I understand it corectly from your build that you designed a ribbed wing yourself? If so can you share the plans or details of the wingfoils used at the root and tip as well as the size of the spars?

Looking forward to the completion of your modell.

I'm also living close to the aviodrome where they have at least 2 Alsema Sagitta glider in their posession. For details I can go there if you need to have more information.

looking forward hearing from you.

regards,

Gerhard
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B Sharp
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Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: Alsema Sagitta 1:4 scale

Post by B Sharp »

Gerhard, I decided to draw the plans for a built-up wing as I could achieve a more scale like structure than would be achieved with a foam wing. The profile I used was the HQ 3.5/14 which I knew from experience would give very predictable handling, especially at low speed. I kept the same profile at the wing tip and did not include any washout. The 14% thickness of the tip rib would allow for the use of a 6.5mm x 3.2mm top and bottom spar at that point. The plans that I drew were quite detailed for the starboard wing so that I didn’t have to think too much during the building process. The port wing plan was achieved by hanging the plan on a patio door light box and tracing through to the back side of the plan. If you look back through the build thread you will see most of the internal layout of the wings. I used the “Profili” app to draw the ribs producing a print out of each rib individual having taken the chord from the plan. This allowed me to design in the building tabs very accurately.

I have not posted any progress on the Sagitta lately as vacations and flying events have kept me busy. However I have finally built up the courage to tackle the canopy glazing.
I decided that the glazing had to be applied in one piece. I felt that I would never get a good fit if I attached the front section and then tried to get the removable rear section to match. First of all I had to fix a brace to the rear frame to hold it in the correct position alongside the front frame. Trying to get both frames into good contact to the inside face of the glazing was also proving difficult. Eventually I applied a layer of filler to both front and rear frames and taped the suitably protected glazing down into place. Once set and the glazing removed I separated the mating frames with a razor saw. The glazing was glued in place with Evostik contact adhesive, taped in place and left for 48 hours to set thoroughly. I then used the razor saw again to separate the front and rear sections before tidying up the edges. The front glazing was then faired into the fuselage with Upol filler and sanded to a smooth transition as per the plan suggestions.
Brian.
Attachments
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047.jpg
048.jpg
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050.jpg
051.jpg
052.jpg
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