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Old Nov 07, 2011, 11:53 AM
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Bremen/Germany
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Build Log
Schweizer 1-36 from www.aerosente.com

Hello,

this is the start of something BIG ...

... well, not really, rather medium size ... http://static.rcgroups.com/forums/im...ilies/wink.gif
... it has only 138" or 3.52 m wingspan.

Earlier this year, I received a first half-kit of this latest model from Tom Martin`s design board which is now produced and marketed by aerosente. The 1-36 is the fourth in my row of TMRC/aerosente builds (1:5 1-23, Cherokee II, 1:4 1-23) and I still have much fun working with wood and building model sailplanes which are not everyday sights on the field.
Originally, I had planned to start the build already in the Summer, but I had to take care within the family which took away quite some time for the hobby.

As always, I am starting with the wings because I want them ready for the fuselage build - and I think it is boring to duplicate things http://static.rcgroups.com/forums/im...ilies/wink.gif

The entire model will be covered with 1/64" ply which is a first for me but I think that it will be advantageous when it comes to the finish and it resembles more the metal sheet covering of the original.

Tom made things a bit trickier this time as he selected the under-cambered S-7037 airfoil from Selig when glueing the ribs on the lower sheeting which I prefer in any case.
I started out with cutting the wing sheetings from a 1.5 meter square ply sheet on the dining table but this did not proof to be practical and so I moved outside. The half span is some 7" longer than the standard supply length of 1.5 m which will be no problem: The remaining length will be added in small pieces which will not cause strength problems.

The lower main spar is glued down now and I used the laser cut drag spar to define the correct position of the lower dive brake door.
Further I applied some packaging foam sheet on the outside of the sheeting which will press the sheeting into the rib under-camber when tack glueing them with CA.

Maybe this build might raise your interest and further the "woody building".

Herbert
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Old Nov 07, 2011, 11:55 AM
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Oooops, can someone tell me how to handle smileys ;-))

Herbert
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Old Nov 07, 2011, 12:37 PM
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Pilatuspc12's Avatar
United States, CO, Hotchkiss
Joined Oct 2006
1,719 Posts
Hello Herbert,

I just found this thread and have always wanted to build a scale model of the Schweizer 1-36. This will be interesting and I'll follow your build to see how you make things. Congratulations.

Regards,

Randy
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Old Nov 07, 2011, 01:24 PM
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Woodstock 1's Avatar
Ireland, County Kerry, Kerry
Joined Dec 2005
6,993 Posts
Hi Herbert

I can't find a 1-36 in Aerosente's web store ?

Smilies usually work by just clicking on the one you want (on the right)!
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Old Nov 07, 2011, 06:03 PM
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Joined Mar 2004
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Oops, waiting for Herbert so I just loaded it up here: https://gliderworkshop.pinnaclecart....product&id=150 in the Plans Section.

Have fun Herbert!!!

tm
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Old Nov 07, 2011, 06:31 PM
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Dorset, Southern England
Joined Dec 2006
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Herbert, if you want a completely realistic finish, take a look at the stick-on Aluminium sheet here:

http://www.mickreevesmodels.co.uk/~m...ccessories.htm
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Old Nov 08, 2011, 08:43 AM
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Bremen/Germany
Joined Apr 2004
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Hi,

being already so familiar with this project, I totally forgot to tell the "interested public" what airplane a 1-36 is ..., but of course, Tom was able to help quickly. Thanks!

Chris, thank you for the covering hint! I shall add this page to my favorites - but I think I shall paint the plane in order to keep my 2.4 system alive
Nice to have a sign from you!

Back to work!
Herbert

Edit: Thanks also to cvanscho! I tried to drag and drop the smiley ... Now I got it as you see
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Old Nov 08, 2011, 09:01 AM
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Yes Herbert, here is the info on full size courtesy of SSA's Sailplane Directory:

Specifications and Performance
Span: 14.0 m./46.2 ft
Area: 13.07 sq. m./140.7 sq. ft.
Aspect Ratio: 15.15
Airfoil: Wortmann FX61-163
Empty Weight: 215 kg./475 lbs.
Payload: 107 kg./235 lbs.
Gross Weight: 322 kg./710 lbs.
Wing Loading: 24.63 kg./sq. m./5.05 lbs./sq. ft.
Structure: All metal, fabric covered rudder and elevator.
L/D Max.: 31 77 kph/42 kt/45 mph
Min. Sink: 0.67 m/s - 2.2 fps/1.30 kt
72 kph/39 kt/45 mph

Country of Origin: USA
Designer: Leslie Schweizer
No. of Seats: 1
No. Built: 43
No. in the U.S.: 35

History
The 1-36 Sprite, the final glider model
produced by the Schweizer Aircraft
Corporation, was conceived as a replacement
for the 1-26 one class design. It was produced
both in a version with main wheel ahead of
the center of gravity, and one with a nose
skid and main wheel behind the center of
gravity. It has balanced top and bottom
surface DFS type airbrakes with the upper
surface segment set well back forwards the
trailing edge of the wing. ATC.

Specs for Model at 1:4 scale
Wingspan: 138.6 in. (3.52m)
Overall Length: 61.77 in. (1.57m)
Fuselage Width: 5.7" (14.5cm)
Wing Area: 1190 sq. in. (8.26 sq. ft.)
Aspect Ratio: 15.15
All Up Weight: 192 oz. (estimated)
Wing Loading: 23 oz./sq. ft.
Airfoil: Selig 7037
Wing Root Chord: 12.25 in. (31cm)
Wing Tip Chord: 5.6 in. (14.2cm)
Stab Root Chord: 5.45 in. (13.8cm)
Stab Span: 24.5 in. (62.2cm)
Stab Area: 120.5 sq. in.
Vertical Tail Area: 77 sq. in.
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Old Nov 10, 2011, 11:42 AM
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A next step has been made:

First, the ribs which accommodate the servos are reinforced with laser cut ply pieces which themselves need a little work in order to facilitate the servo replacement in the finished wing (you know, I hate "surgery at the open - wooden - heart"). The "aileron rib" received a supplementary cut-out for the servo cable and the "air brake rib" opening was bevelled such that the servo can be slid in "half way sideways" through the lower air brake door opening. This has been checked successfully in the meantime after all ribs were set and glued.

The drag spar and the aileron spar are a very easy jig for positioning the ribs which speeds work considerably, so that the lower air brake hinges and the wing rod will be the next steps.

And, I did not forget to prepare the opening for the aileron servo ...

Herbert
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Old Nov 21, 2011, 10:19 AM
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Bremen/Germany
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Well,

building progress fast faster than keeping track here in the build blog ...

The ribs were set, webbings in place - after positioning of the wing rod tube! - and then, I attacked the reinforcement of the air brake openings and the hinging. Tom`s plan shows all details as far as film hinges are used, but I prefer "classic" hinges which cause a little extra work. One of the advantages is the possibility to take off the doors completely whenever I need to have access to the servos for adjustments or servicing.

Herbert
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Old Dec 20, 2011, 07:25 AM
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Bremen/Germany
Joined Apr 2004
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Sorry,
I kept you waiting quite long for the next update. Travelling in the meantime and other commitments kept me away from the shop, but nevertheless I made some progress.

A little this and that: wooden blocks at the root rib for the MPX wing retaining lock, a piece of tubing for the wing root pin, balsa strips at the trailing edge for an increased glueing surface for the top sheeting and, as it turned out, the "major issue" how to fix the servos in the ribs which then would allow their mounting and removal when the wing is finished.
After some tinkering in and off the shop, I came up with a very simple solution: I reinforced the lower sheeting and drilled screw holes immediately beneath the servo flanges. The screws are inserted from the outside with the screw heads sticking out a bit as there is not enough room (at the aileron servos) to use flush flat headed screws. I am confident that this will not ruin the flight performance ...
For the rear air brake servo side, I used a bracket which has access from the lower brake door.

There I am now ready for the top sheeting. I shall use the "white-glue-iron-on-method" for the first time and had another lengthy phone call with my club fellow Michael www.m-ohlwein.de who has ample building experience and who told me a number of additional "how tos" ...
But this will have to wait until after Christmas.

In the meantime I wish all followers a

Merry Christmas and a happy and successful New Year
Herbert
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Old Jan 31, 2012, 05:59 PM
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Bremen/Germany
Joined Apr 2004
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Hi,

time to report the progress as we moved into the new year and are looking forward to better weather.

The next step was the top sheeting which I did in two steps because I wanted to implement a 2 wash-out and avoid warping problems with the ply material.

Using the trailing edge as a reference I first had to find the precise position for the upper air-brake cut-out which I managed successfully with some "precision measuring"
As far as glueing is concerned, I used the white-glue-iron-on method for the first time and it worked easier than anticipated. The (undfortunately bad) picture shows the method: White glue (a slow drying variant) is applied relatively thick on both sides and then it is set aside to dry until the white color becomes shiny and translucent and is hardly sticking anymore (some 20 to 30 minutes). Then both sides are joined and ironed down like it were covering film. The joint must be held in place until it has cooled down - and that`s it!
I then applied the leading edge - really hard balsa - and shaped it roughly. Final sanding, aileron cut-out and air brake doors will be done when the plane approaches completion.

In the meantime I started with the stabilizers and with the fuselage soon ahead, there will be more interesting stuff to tell.

As I keep saying: wing building is boring

Herbert
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Old Feb 21, 2012, 08:02 AM
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... and building tail surfaces as well ... ?!

Any way, I equipped the stab with two small digital servos because I don`t appreciate bowden cable (or "snake") linkages very much as they either tend to bind or to be too sloppy.
Otherwise the build does not require particular tricks besides a good "symmetrical" eyesight as long as you assemble the basic frame without a jig - as I did
... and this time, I even managed to get a straight rudder - with "jig" ...

I hope to start the fuselage soon and this will probably show a few more interesting details?

Herbert
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Old Apr 03, 2012, 11:17 AM
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Fuselage started ...

... with the wing joiner rod/ central fuselage former(s) assembly - as I prefer since long. Again no attempt to bend the aluminum rod, not the least because I do not want to have the rod ends sticking out during transportation. The ugly piece of wood in the center below the rod joiner box serves as an additional (psychological) support at the spot where the two rod pieces meet ...

I continued framing up the front part of the fuselage which is simple and straight with the precision lasered parts. Only when adding the rear part, the stanchions were of great help!
In the meantime, all stringers are in place and I covered also two upper fuselage sections with ply in order to provide some stiffness to the fuse when the alignment and build of the fin comes as the next step.

Herbert
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Old Apr 03, 2012, 12:07 PM
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United States, KY, Taylorsville
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Thanks for posting!
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