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Alsema Sagitta 1:4 scale

Posted: 10 Dec 2021, 09:54
by B Sharp
As I mentioned in the “Who’s building what 22” thread a short while ago my project for this winter is the Alsema Sagitta.
Having drawn new wing plans and made adjustments to the Vic Steel fuselage and tailplane plans I was ready to make a start. I have spent a couple of weeks of spare moments cutting out formers and wing ribs. The formers are from Vic’s hand drawn plans and will likely require a bit of fettling to get a good fit. The wing I have planned is using HQ3.5/14 at the root and HQ3.5/10 at the tip. As the wing is highly tapered this should prevent tips stalls on landing approach.
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 10 Dec 2021, 11:40
by Max Wright
She looks very sleek. 8-)

What is the story with the "tip tanks" ?

If I don't ask, I won't learn nuffin. ;)

Re: Alsema Sagitta 1:4 scale

Posted: 10 Dec 2021, 17:20
by Peter Balcombe
Max, i would have thought the tip “tanks” are more likely a combination of wing fence & tip skid - they are a bit like the plate types fitted to the 1950s Jaskolka i am currently building.

Re: Alsema Sagitta 1:4 scale

Posted: 10 Dec 2021, 19:51
by Max Wright
Thanks, Peter.

Re: Alsema Sagitta 1:4 scale

Posted: 11 Dec 2021, 09:42
by B Sharp
Max.
The data that I have collected on the Sagitta shows a number of options for the wingtips. The American examples (N6446 and N99999) both have flat plate wingtips as do PH-308, PH-319 and PH-403. I can find only one example with a round profile (like a jet wing tank) but I can’t make out the registration. The example I am modelling (PH-266) has the same elevation profile as the others but appears to have a thicker plan profile.
I think that their prime purpose is to form a wingtip skid. I don’t know if there is any aerodynamic benefit such as tip vortex management.
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 11 Dec 2021, 10:44
by Max Wright
It's all interesting, Brian. 8-)

Re: Alsema Sagitta 1:4 scale

Posted: 12 Dec 2021, 01:47
by Jilles
Some more info on the Sagitta. There were 21 built including one Super Sagitta, this last one had a 17m wing span instead of 15m. I did wittness the maiden flight of this Super Sagitta myself. They were built at the Teuge Airfield in the Netherlands. It was a small workshop owned by Mr Bauling.
They did build many Grunau Baby"s after WW2 and these were called Bauling Baby's as did Fokker and were called Fokker Baby's
To keep the factory going the Sagitta was built, designed by Piet Alsama. It was suppose to compete with the Schleicher ka6 and Slingsby Skylarcs.
With the introduction of the first glass gliders of that time it never reached high production numbers.
I did fly the Sagita myself. It was a high performance glider for the time and required your constant attention to make it fly to max performance.
With the all around canopy the pilot had a 360 degree view. It could tip stall and some have come to grieve during landing by making the last low turn to slow. It did thermal well. The maximum speed was 270k/h, and the glide ratio 34:1 what for the time was very good. It was fully aerobatic, without any restriction apart from the max. speed
The tip tanks as far as I know were only used on the prototype. The production versions had the plank type tips ends because it reduced construction time/costs. The purpose was to protect the wing underside on the ground and also to reduce the tip stall a bit as was recognised during the first test flights.

I did design a 4.8m wing span model of the 15m Sagitta version. it was built in New Zealand and I did own and fly it myself untill it was sold to an other guy in N.Z. The model perfomed very well. I live in Australia so I had not much oppertunity to fly the Sagitta in N.Z. the reason it was sold in N.Z.
Cliff Evans has the details in case somebody is interested to build this model. The model 3 view drawing is attached

Re: Alsema Sagitta 1:4 scale

Posted: 12 Dec 2021, 09:27
by Cliff Evans
Jilles's plans are in the repository.

Re: Alsema Sagitta 1:4 scale

Posted: 13 Dec 2021, 11:53
by B Sharp
Thanks for the additional info Jilles.
I did download your PDFs when they were first produced and it was my intension to build from your plans. However my date of birth has caught up with me and I am trying to restrict my builds to under 7kg as I have a long walk to carry the finished model up to my local slope. This is why I am building a 1:4 version.
However I have used your plans as a reference for the wings, tail and parts of the fuselage when planning my build. Thank you for that.
Brian.

Re: Alsema Sagitta 1:4 scale

Posted: 29 Dec 2021, 19:41
by B Sharp
Sorry about the delay since my last post but I was a bit busy with other things and then we had the festive nonsense which took me on an expedition up to the wild and wintery north.

I have mounted the formers on my jig using ply up-stands to get them all sitting at the correct height. The top longeron and front upper support were dry-slotted into place and then the middle side longerons offered up to the formers. Of the thirteen formers seven had to be removed from the jig and the slots in the sides adjusted before the longerons looked anything like straight. I now have the partially complete structure dry jointed and clamped together while I investigate the positioning of the other longerons. What I have discovered is that several of the formers have slots for longerons where nothing appears on the plan or side elevation. Stranger and stranger? :shock:

To make things worse I have under ordered the ¼ square spruce that I require as I think I only calculated for one side of the fuselage. :x

Brian. :(

Re: Alsema Sagitta 1:4 scale

Posted: 30 Dec 2021, 12:26
by B Sharp
The problems with the former slots continue to get worse and worse the further I proceed. Aft of the wing I have started drawing lines on the edges of formers using a straight edge between the furthest forward and furthest back formers then cutting new slots. This allows the longerons to sit in a straight line forward to aft. I will have to fill in the gaps at a later date. :(

In the centre of the fuselage things are a bit more serious. The longerons that form the edge of the cockpit were sitting well proud of two of the main formers. As these longerons are critically positioned to seat the sliding canopy they have to be precise. Consequently I have had to add extensions to the top of each former and will have to adjust the sides when it comes to adding the skin of the fuselage at that point. :(

I am now regretting not redrawing the fuselage plans and using “Devcad” to draw the formers. I’m sure I could have made a better job than the old hand drawn plans. :cry: :cry: :cry:

Brian.

Re: Alsema Sagitta 1:4 scale

Posted: 05 Jan 2022, 17:14
by B Sharp
While I wait for more ¼ square spruce to arrive so that I can complete the longerons I have started to fill in the front of the fuselage.

Now normally I would have planked the whole of the fuselage with 1/8 balsa, however this plan specifies a different method. The plan requires me to infill between each of the longerons and formers with ¼ balsa cut and tapered to shape. This seems a very odd way of doing things and I am not all that happy with the results so far. Once the fuselage is covered in this manner back to the rear of the wings it can all be carved and sanded. The final instruction is to coat it in filler and sand back to the required final shape.

Has anyone tried this before and does it make a good job?

Brian. :shock: :shock: :shock:

Re: Alsema Sagitta 1:4 scale

Posted: 06 Jan 2022, 01:12
by Cliff Evans
Vic Steel used this method on most of his models. I personaly don't like this method.

Re: Alsema Sagitta 1:4 scale

Posted: 06 Jan 2022, 11:58
by B Sharp
This is the first time I have built one of Vic's designs so was totally unaware of his methods. I have seen a number of his aircraft flying and they looked just fine. However I supose I will just have to continue and see how I get on.
Brian. :?

Re: Alsema Sagitta 1:4 scale

Posted: 09 Jan 2022, 17:35
by B Sharp
As my fresh timber has not yet arrived I did a little more of the infilling of the front end of the fuselage. In doing so I blocked out the front cockpit coaming as well. When all the glue had set I rough carved with a David Plane and then sanded back with 80 grit paper. After I had done a bit of filling with wood filler and then sanded that back as well, the nose of the fuselage was looking better than I had expected.
I still don’t like this form of construction but I now think I will be able to get a half decent finish after all.
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 09 Jan 2022, 23:46
by Jilles
glassing with a layer of 25gr/m2 cloth will make it even better and prevent dents in the softer balsa during handling
I did the same on my 1:3 ka8
the way to go on strong compound curves when the finish will be a paint job
You need weight in the nose anyway just as well make it useful.

Re: Alsema Sagitta 1:4 scale

Posted: 10 Jan 2022, 11:33
by B Sharp
Jilles, thanks for the encouragement to continue with this form of “sheeting” on the fuselage. It is helpful to see that other builder successfully uses this method as well.
The infill between the longerons/formers continues to the rear of the wing. Aft of that the fuselage is covered in 1/64 (0.4mm) birch ply which will be wrapped round the structure.
It was my intension to cover the whole fuselage and fin in 50gm/m2 glass cloth & epoxy as I have done so often in the past. I would then skim with Upol where needed and sand back to a suitable finish before painting.
My timber has just arrived so I will concentrate today on finishing the application of the longerons before continuing the sheeting of the front end.
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 24 Jan 2022, 17:09
by B Sharp
It’s been a couple of weeks since my last post and the Sagitta has progressed a little. Most of the front fuselage planking/sheeting is now complete. I will complete the underside once the airframe is removed from the jig. By the way, I still don’t like this form of construction! :?

I realised that I can’t sheet the rear of the fuselage until I had the fin assembly built. Having built the fin I found I required the rudder to check everything fitted properly so that was built as well.

I now find that it would be a good time to built the tailplane so that it’s a bit easier to get all that aligned without being fixed to the fuselage. So that’s next on the board.

Brian. :)
Front of fuselage pretty much built.
Front of fuselage pretty much built.
Fin and rudder.
Fin and rudder.

Re: Alsema Sagitta 1:4 scale

Posted: 29 Jan 2022, 19:23
by B Sharp
I have had the whole day to myself in the workshop today and have started on the tailplane construction. Once again the ribs as shown on plan don’t match up with the tailplane plan view and I have had to re-draw about half of them. However the tailplane halves went together quite well and the joiner tubes (carbon, it was what I had of the correct size) matched up perfectly. I consider that to be quite a result.

The top sheeting is now in place and I have started making provision for the elevator servos. The servos I have chosen are small but are alleged to put out 1.75kg of torque at 6.0 volts. I have estimated that this will be more than enough for the designed elevator size provided that I can make the hinges as free moving as is possible.

Brian. :)
Basic tailplane structure.
Basic tailplane structure.
Top sheeted and servos possitioned.
Top sheeted and servos possitioned.

Re: Alsema Sagitta 1:4 scale

Posted: 30 Jan 2022, 22:35
by B Sharp
I finished sheeting the tailplanes today by adding the undersides and servo hatches. I then set about installing the joiner tubes in the fin. I have used the same 6mm carbon tubes that I used in the tailplane halves.
I spent an absolute age setting the front tube to ensure that It was mounted square in every direction before locking it in place with cyano. After that setting up the rear tube was a piece of cake using the tailplane halves as a jig.
The only downside of using carbon is that when you sand it you get black dust everywhere and it stains the timber sheeting. However that will eventually disappear after a glass/epoxy/paint finish.
Brian. :)
Completed tailplane halves.
Completed tailplane halves.
Carbon tubes mounted in the fin.
Carbon tubes mounted in the fin.
the almost complete tail assembly.
the almost complete tail assembly.

Re: Alsema Sagitta 1:4 scale

Posted: 09 Feb 2022, 17:27
by B Sharp
The construction of the tail feathers is now complete. The tailplanes are finish sanded and are drilled for Robart pin hinges. The elevators are also finish sanded and similarly hinged. The slots for the epoxyboard control horns have also been cut. I was very tempted to continue by covering the tailplanes and elevators with Diacov1000 but I decided to err on the side of caution. So many things have gone wrong on this build that waiting till the fuselage and wings are completed seemed a sensible option.

The fuselage has been removed from the jig and the front underside blocked in with 6mm balsa. The 3mm alloy undercarriage mount has been securely glued and bolted to the 6mm ply fuselage crutch. I have also now created a floor for the cockpit and installed a servo and receiver mounting tray.

My last job this afternoon was to go over all the seams and blocking on the forward fuselage filling the gaps (of which there were many) with Ronseal lightweight timber filler. The image below shows why I still don’t like this method of construction!

Brian.
Servo/Rx mount and cockpit floor.
Servo/Rx mount and cockpit floor.
Undercarriage mount.
Undercarriage mount.
This is why I dont like this construction method!
This is why I dont like this construction method!

Re: Alsema Sagitta 1:4 scale

Posted: 10 Feb 2022, 09:24
by RobbieB
Hope that Ronseal filler is good stuff Brian - just ordered some. My last tub of Red Devil wouldn't go off.

Definitely not a nice form of construction that Sagitta - not sure how much strength it adds to the structure either.

Re: Alsema Sagitta 1:4 scale

Posted: 10 Feb 2022, 14:59
by B Sharp
Robbie, Yes you are right . If I had thought things through before starting I would have reduced all the formers by 1/8 inch all round and then planked the fuselage as I normally do.
The Ronseal filler is fine, I have used it for all wood filling for years now. It goes on easily, dries to a crisp finish, is easily sanded and tastes of strawberries. (just joking about the last bit) The only problem I have found is that if you open the tin and then set it aside for a couple of months it can go hard.

Today I sanded off the filler on the forward fuselage and it looks a little better. I prepared the rear fuselage for sheeting. I spent an hour or so making a template for each side of the fuselage then marking the 1/62 ply sheet before cutting. I have now marked up the inner sides of the 1/64 sheets with the former and longeron positions ready to apply PVC glue prior to ironing into place.

Brian. :)
1/64 ply skins almost ready to attach.
1/64 ply skins almost ready to attach.

Re: Alsema Sagitta 1:4 scale

Posted: 10 Feb 2022, 15:09
by Peter Balcombe
B Sharp wrote: 10 Feb 2022, 14:59 I have now marked up the inner sides of the 1/64 sheets with the former and longeron positions ready to apply PVC glue prior to ironing into place.
Brian,
If you apply PVA to the fuselage contact areas & then temporarily place the skin piece, it will transfer glue to the skins where it was on the fuselage side. Remove the skin & the glue imprint should be there. Let the glue dry & refit to iron on.
Makes things much easier when you have long D box skins & the like. (But I’m sure you knew all this anyway ;) )

Re: Alsema Sagitta 1:4 scale

Posted: 14 Feb 2022, 17:38
by B Sharp
I have done quite a bit on the Sagitta in the last few days.
I cut up half disks of church roof and attached it each side of the nose cone. This will be covered with filler when I skim coat the whole front end.
The rear fuselage skins went into place with very little trouble at all. However I am disappointed that the 1/64 ply is so thin that the underlying structure shows through. If I had used 1/32 ply for the skinning it would have held the profile rather better but would have been twice as heavy. However I can’t do anything about it now. :?
The fin was fixed in place after much fettling and checking and appears to be perpendicular to the fuselage and the tailplane is in line with the datum line. Result! :D
The elevator servo cable (with plugs and sockets fitted) running to the receiver has been installed and attached to the framework to keep it in firmly place. I am using a PTFE tube and bowden cable for the rudder and that has also been installed. :)
Finally the very rear of the fuselage has all been blocked in and sanded to profile. :)
Brian. :)
Lots of church roof!
Lots of church roof!
Skinning added.
Skinning added.
Fin in place and fuz blocked in.
Fin in place and fuz blocked in.
Starting to look like a fuselage!
Starting to look like a fuselage!

Re: Alsema Sagitta 1:4 scale

Posted: 16 Feb 2022, 19:21
by B Sharp
More compromises!

I had intended to have an opening canopy on the Sagitta. On the prototype there is a front wrap-around windscreen with the rear canopy sliding back on rails. Now, all of this is shown on the plan, and I intended to set it up as per instructions. I spent some time making up the sliding rails and it was only when I tried to incorporate them onto the cockpit opening that I realised that there was a major problem. The fuselage sides are not parallel but taper towards the rear. The front windscreen will fit without a problem but the rear canopy section will never slide as the distance between the rails narrows all the way back.

I went back and checked the plans and they show the fuselage being parallel between F4 and F5 and then tapering back through F6 and beyond. The rails as shown are straight all the way back as far as F6 (how does that work?). When I checked the drawn formers on the plan F5 was narrower than F4 and F 6 was narrower than F5. Since I used the drawn formers in my fuselage build, it was always going to be tapered!
I left the workshop in disgust!

Having calmed down I decided to make the rear cockpit canopy totally removable. The rear canopy frame has been cut and will now be held in place with button magnets at the rear and piano wire pegs at the front. I am not happy but it is the best compromise I can make. I have to say that this project is within a whisker of getting thrown in a corner and allowed to rot!

Brian.
The tidied up cockpit area.
The tidied up cockpit area.
Plan View showing tapering fuselage sides.
Plan View showing tapering fuselage sides.

Re: Alsema Sagitta 1:4 scale

Posted: 16 Feb 2022, 23:26
by Barry_Cole
Stay with it Brian....

8-) 8-) 8-) 8-)

BC

Re: Alsema Sagitta 1:4 scale

Posted: 17 Feb 2022, 07:58
by Trevor
Yes, I'm sure there must be an ancient Chinese saying along the lines of 'The light shines brightest at the end of the darkest tunnel' !

Re: Alsema Sagitta 1:4 scale

Posted: 17 Feb 2022, 10:49
by Philkiteflyer
Trevor wrote: 17 Feb 2022, 07:58 Yes, I'm sure there must be an ancient Chinese saying along the lines of 'The light shines brightest at the end of the darkest tunnel' !
Whooo . . That's deep man . . ;)

I did a bit of web surfing and may have the answer. I found some pics of canopies open and I 'think' (just my quess :? ) the canopy slides on the front two and a central rear slide of some sort.
I have attached the photos to show why I think this.
Maybe I'm clutching at straws . . . maybe someone can get access to the full size to clarify this puzzle.

Good luck
Phillip C
New Zealand.

Re: Alsema Sagitta 1:4 scale

Posted: 17 Feb 2022, 17:49
by B Sharp
Thanks for the images Phillip. This is exactly what I had envisaged building when I started this project. It is also what is shown on part of the plan and in the magazine write up which accompanied the publication of the plan.

However it was only once I had constructed the side rails from the plan and did a trial fit that I realised that they would not work. At that point I had even produced the sliding tube mechanism for the rear of the canopy.

As I said in my last post, the sides of the fuselage taper inwards from F4 (the break in the front/rear canopy) aft. If I were to place the rails on the fuselage sides as directed the canopy would be crushed inwards as it was slid rearwards. Because of the canopy frame being rigid the canopy would not slide rearwards as it would quickly become jammed in the side frames.

The problem comes from me trusting that the formers as shown on the plan were correctly drawn to allow the sides at the cockpit to be built parallel. In actual fact they are inaccurately drawn and produce a tapered opening. By the time I have reached the present juncture it is too late to alter the structure as that would require me to tear the whole centre of the fuselage to bits in order to insert two new formers.

It all comes down to trusting someone else’s hand drawn plans. I should not have been lazy and drawn my own plans in the first place.
Every Day Is A Learning Day!! :?

Brian. :? :? :?

Re: Alsema Sagitta 1:4 scale

Posted: 18 Feb 2022, 10:32
by Philkiteflyer
Hi Brian, I didn't realise you were doing a three point slider, I tried to find drawings of the system but could only find those pics.
Pity you do the slider, its a bit of a feature - like the Foka forward sliding canopy - very sexy.
So I suppose you could do the side opening one like this . .
Sagitta Canopy-pivoting.JPG
Theres a few pics of this glider through its life and the canopy got changed a few times . . so plenty of choice.

Good luck for rest of build, hope it gets easier . .
Phillip C

Re: Alsema Sagitta 1:4 scale

Posted: 21 Feb 2022, 01:20
by Jilles
the Sagitta canopy has changed during the production of the 21 built
I did fly the full scale in the 1970's in the Netherlands
This one had a three part canopy, a fixed front and rear section abd a sliding centre piece
you could slide the centre piece two or three steps backward during flight for more ventilation but at a cost of more noise.

Re: Alsema Sagitta 1:4 scale

Posted: 22 Feb 2022, 19:20
by B Sharp
Thanks to all the gentlemen who have provided options for me in the last few post.

The fate of the canopy has now been finally decided. The whole of the rear canopy section will be fully removable. The front will be located by two pins which will locate into brass tubes fixed into the rear of former #4. The rear of the canopy will be held in place by two 12mm button magnets in the rear of the cockpit opening and canopy frame. This will have the added advantage of giving me full access to the radio bay which sits behind former #5.

The whole front of the fuselage has now been given a skim-coat of upol filler and is now awaiting sanding back to a finished surface.

Brian :)

Re: Alsema Sagitta 1:4 scale

Posted: 24 Feb 2022, 19:49
by B Sharp
Since the last post I have sanded back the filler skim coat on the fuselage till I arrived at a shape that I was happy with. I used two full tins of elbow grease in the process.

I am redecorating in the house at the moment but between coats of paint I managed half an hour to put 50gm/m2 glass cloth and epoxy on one side of the fuselage. I will get the second side glassed tomorrow with a bit of luck.

Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 28 Feb 2022, 17:15
by B Sharp
The fuselage is now fully covered with glass/epoxy although I have not sanded it back with wet & dry as yet. I will leave it a few weeks to become fully crisp. :)
However I have now created the wheel fairing attached to the bottom of the fuselage. As you can see from the image below it is a 1/32 ply and balsa affair constructed round the alloy wheel mounts. This will also get a glass/epoxy coat in due course. :)
This afternoon I have made a start on the wing construction by scarfe joining the spruce spar material. :)
Brian. :) :) :)

Re: Alsema Sagitta 1:4 scale

Posted: 02 Mar 2022, 18:15
by B Sharp
I spent the afternoon producing a short kit for the wings of the Sagitta. The spars are manufactured from 1/2in x1/4 in spruce stock which I have tapered out to 1/4in x 1/8in at the wing tips.
In the image below you will see that I have produced the spars, sub spars, false leading edges, trailing edges, wing joiners and wing ribs. All now ready to go!
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 03 Mar 2022, 16:38
by B Sharp
Work started on the left wing this afternoon. With all the ribs glued in place to the bottom tapered spar. The joiner box was then epoxy glued to the spar and squared up in all three dimensions. On this occasion I did remember to drill the holes in the wing ribs for wiring before they were fixed in place. So far, so good!
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 09 Mar 2022, 19:01
by B Sharp
Progress on the wings has been a bit slow this week as I have flown three times in the last week as well as working on my garden.

I took a lot of time installing the wing incidence peg as it has to be totally in line with the main joiner. It is now in place and secured solidly.
The other spars, sub spar and webbing are now glued in place and trimmed. The electric air brake has also been installed along with the aileron servo wiring.

Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 15 Mar 2022, 08:53
by B Sharp
The top wing sheeting is now in place as well as all the cap strips on the exposed ribs at the trailing edge. The bottom sheeting will possibly go on this afternoon.
Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 15 Mar 2022, 22:29
by Jolly Roger
Looks fab Brian. Tidy work.

Re: Alsema Sagitta 1:4 scale

Posted: 17 Mar 2022, 17:22
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. :)

Re: Alsema Sagitta 1:4 scale

Posted: 28 Mar 2022, 19:23
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. :)

Re: Alsema Sagitta 1:4 scale

Posted: 13 Apr 2022, 16:56
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. :)

Re: Alsema Sagitta 1:4 scale

Posted: 28 Apr 2022, 20:24
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. :)

Re: Alsema Sagitta 1:4 scale

Posted: 29 Apr 2022, 09:24
by Cliff Evans
Very nice Brian.

Re: Alsema Sagitta 1:4 scale

Posted: 29 Apr 2022, 15:39
by Phill Tadman
Lovely stuff

Re: Alsema Sagitta 1:4 scale

Posted: 30 Apr 2022, 17:37
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

Re: Alsema Sagitta 1:4 scale

Posted: 30 Apr 2022, 17:42
by Peter Balcombe
Looking very good Brian 👍

Re: Alsema Sagitta 1:4 scale

Posted: 07 Jun 2022, 21:32
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

Re: Alsema Sagitta 1:4 scale

Posted: 09 Jun 2022, 17:07
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.

Re: Alsema Sagitta 1:4 scale

Posted: 11 Jun 2022, 17:54
by gait
Brian ,

Thx for your info. I’m using devwing to set-up the wing. I’ll have a look into the design.

Br,

Gerhard

Re: Alsema Sagitta 1:4 scale

Posted: 28 Jun 2022, 19:01
by B Sharp
It’s been a little while since I last posted as my attention has been focused elsewhere. However I have now started on the paintwork – not my favourite task. The fuselage is sprayed in a white and red scheme which appears fairly simple. When I had the white undercoat in place it shows up all the imperfections in the structure. There then followed a period of re-applying filler to certain areas and sanding once again. This was followed with more primer. Once the rattle-can Appliance Gloss White gloss coat was applied all the lumps and bumps became even more apparent. I came to the conclusion that most of this was down to the fuselage structure and there was only so much corrective filler that I was prepared to apply as it was all adding weight. I have also now added the red colouring to the undersides and the fin flash. All in all, I am not happy with the finish but it will just have to suffice – it will look Ok when 50ft away. :?
You will also see from the photos that I have added the rudder and am presently in the process of mounting the servo and control runs. :)
Brian. :? :? :?

Re: Alsema Sagitta 1:4 scale

Posted: 28 Jun 2022, 22:17
by Jolly Roger
Finish looks good to me Brian. The full size all have bumps, dings and waves, so you’ve just built in extra authenticity. :D

Re: Alsema Sagitta 1:4 scale

Posted: 29 Jun 2022, 10:20
by B Sharp
That might be so Roj, but I am still not best pleased with the finished article.
Brian. :?

Re: Alsema Sagitta 1:4 scale

Posted: 29 Jun 2022, 11:54
by Cliff Evans
B Sharp wrote: 29 Jun 2022, 10:20 That might be so Roj, but I am still not best pleased with the finished article.
Brian. :?
Don't be such an old fusspot!

Re: Alsema Sagitta 1:4 scale

Posted: 08 Jul 2022, 19:19
by B Sharp
It's the "Old Fusspot" here!

I have not been idle since my last post. The airframe is now all painted. The servos and pushrods are installed and working in the correct directions. Joiners and connectors are installed and functioning. And the mono-wheel has been installed. The LiFe battery has been installed as well as a voltage regulator.

Today I carried out the first full assembly of the model and it all seemed to fit together without any additional fettling. :)
I worked out the ideal CofG position on my favourite CG calculator using a static margin of 15% as a starting point which gave a CofG position 120mm back from the wing leading edge. I also calculated a position with a static margin of 12.5% which moved the CofG back a further 5mm. As a matter of interest I carried out a calculation based on the indicated position on the published plan and this indicated a static margin of 25% which would indicate a very nose-heavy trim. :o

Brian :) :) :)

Re: Alsema Sagitta 1:4 scale

Posted: 08 Jul 2022, 23:00
by Jolly Roger
It looks beautiful, Brian. Great job! Hope you bring it down to Leek and Moorland in a few weeks.
Rog

Re: Alsema Sagitta 1:4 scale

Posted: 09 Jul 2022, 10:45
by B Sharp
Thanks Rog, and yes I hope it will be in the car.

It's yet another post by the "Old Fusspot"!

The model is now fully balanced and has gone through all the control checks and settings this morning. As it was a nice morning I took the Sagitta outside for it’s official "I’m now complete" photos which you will find below.
I am now waiting for a suitable 10 to 15mph from the southwest or the east so I can lob it of a hill for the first time. I will keep you posted as to the results.

Brian. :)

Re: Alsema Sagitta 1:4 scale

Posted: 10 Jul 2022, 20:58
by Antonia
Looking really good Brian, hope the maiden comes soon for you :)

Re: Alsema Sagitta 1:4 scale

Posted: 11 Jul 2022, 20:57
by B Sharp
She Flies!!!
Well, that was Ok!
Weather conditions were forecast to be near perfect for today so the Sagitta batteries were fully charged. Mid-day saw me atop my SW slope with a 10 to 12mph breeze blowing direct onto the slope. I had added a bit of up-trim to the elevators as a precaution for this maiden flight but in the event that proved to be a mistake. I spent the first couple of minutes trying to re-trim to avoid the model stalling. :o
Once I got the Sagitta flying straight and level it proved quite pleasant to fly. After landing I increased the aileron differential a little and decreased the elevator sensitivity and this seemed to do the trick as the second flight was very pleasant.
By the third flight the wind had increased to 18 to 20mph and I discovered that loops, rolls, stall turns and Cuban eights were possible as well as taking a few shots with my camera (see below). I hooked a nice big thermal which took the Sagitta up to 380m which gave me more than enough height to cross-country the half mile back to near my parking spot.
Happy Days! Brian. :D :D :D :D :D

Re: Alsema Sagitta 1:4 scale

Posted: 11 Jul 2022, 21:51
by Trevor
Excellent! Congratulations.

Re: Alsema Sagitta 1:4 scale

Posted: 11 Jul 2022, 21:58
by chris williams
Nice one, Brian...

Re: Alsema Sagitta 1:4 scale

Posted: 12 Jul 2022, 13:38
by Cliff Evans
Well done Brian.

Re: Alsema Sagitta 1:4 scale

Posted: 12 Jul 2022, 15:59
by RobbieB
Good one Brian.

So what's up next?

Re: Alsema Sagitta 1:4 scale

Posted: 12 Jul 2022, 19:27
by B Sharp
Thanks for your kind comments guys and girl.
I have to admit that I fell out of love with this project several times during the build. However, the relatively problem free maiden has softened my feelings for the Sagitta. So much so that it is likely to be in the back of my car for my next three trips “south of the big wall”. :)

Robbie, I have no new builds scheduled for the rest of this year. Unfortunately I will be spending my time undertaking three (yes three) repairs to my existing fleet. Yes, hard to believe isn’t it. :shock: :shock: :shock:

Brian (The Old Fusspot) :lol: :lol: :lol:

Re: Alsema Sagitta 1:4 scale

Posted: 12 Jul 2022, 20:26
by simon_t
Great job Brian. Looks very nice, and you must be very happy with the combination of thermalling and aerobatic performance. I look forward to towing it sometime behind the Porter.

Simon

Re: Alsema Sagitta 1:4 scale

Posted: 14 Jul 2022, 07:57
by patte de loup
Nice ;)
Pat'

Re: Alsema Sagitta 1:4 scale

Posted: 19 Jul 2022, 10:45
by gait
Hi Brian,

Finish is looking great! congrats with you maiden. :D
Inspiring to start my build.

many happy landings !

gr.

Gerhard