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Mar 24, 2005, 11:13 PM
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Schweizer 1-36 Sprite Build-up

Over the next few weeks I will be building up a composite Schweizer SGS 1-36 Sprite from our kit components for a customer.

Thought it would be interesting to post the buildup in a thread here on RC Groups. Attached is image one, the components and parts laid out before beginning the build. The color scheme will be red and white NASA markings and insignia to match the Deep Stall Test aircraft employed by the agency at Edwards Air Force Base.

Scale: 1:5
Configuration: Shoulder mount wing, T-tail, fixed stab with dual elevators.
Wingspan: 111" (2.8 meter)
Dihedral: 2.5 degrees each wing (5 degrees total).
Wing area: 760 square inches
Wing aspect: 10.9:1
Channels: 6 (elevator, ailerons (2), rudder, dive brakes, tow release).
Fuselage: epoxyglass with carbon tow reinforcement.
Wings: CNC Wire cut EPS, pulltruded carbon spar, wrapped carbon sleeve,
obechi sheeting.
Carry-through: 13/32" brass sleeve (11.5mm) OD, vertical grain balsa
fillers, 1/8" (3mm) tabbed laser cut ply box attached to full bulkhead.
Joiner rods: 3/8" (11mm) OD solid carbon rod (2) 8" overall length each side.
Landing gear: Tail dragger (forward of CG) 2 1/2" (63.5mm) diameter main
on 5/32" steel wire axle with stop collars in 1/8" plywood mounts.
Canopy: vacuum formed clear lexan on 1/8" (3mm) ply frame,
side-hinged left side as in full scale.
Instrument panel: 1/32" G-10 glass laser cut with bezels, clear lenses, and
full color instrument faces.

Last edited by mmartin55; Mar 31, 2005 at 12:33 AM. Reason: ID change to OD in specs for wing joiner sleeve
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Mar 24, 2005, 11:22 PM
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Those fuses sure look huge until you get the bits together. Great looking kit, should be a fine looking ship when done. Should be like a snap together with those laser cut parts.

Mar 24, 2005, 11:33 PM
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NASA Deep Stall Schweizer 1-36 Aircraft

Here is picture of the NASA aircraft I will be modeling this one after. Of course ours wont have the ability to dislocate its stab like this to induce a deep stall but, hmmmm maaaaaybeeee........

Mar 25, 2005, 12:15 AM
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nice cant wait to see how it turns out , im so used to seeing foamie versions of this kit , and i is quite possible to use this mechanizim on the model , it is called a dethermalizer and they used to be used on free flight models and if you look into it i think cermark has a kit with a simialiar system...
Mar 27, 2005, 02:35 PM
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SGS 1-36 Fuselage Assembly

Here is what you will need for the first operation:

3M Scotch-Weld DP 460 epoxy adhesive,
Mixing cups,
Sticks for mixing and applying adhesive,
Masking tape,
Rotary tool with a cutoff wheel for cutting and trimming fiberglass,
Electric drill,
5/16" drill bit for 8mm nose release
13/32" drill bit for wing joiner openings in fuselage
Hobby saw,
Hobby knife,
Sanding block with medium paper for trimming 1/8" ply as needed,
Two small woodworking "C" or quick clamps,
Small tubing cutter,
Pencil or fine felt-tip pen,
Small tape measure or ruller,

Plan drawings for the model,
Instruction book,
Glass fuse,
Laser cut parts kit,
Brass joiner sleeve,
Supplied template for landing gear wheel well opening,
Mar 28, 2005, 09:46 PM
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Test fit all laser cut plywood 1/8" parts inside the fuselage and align as shown on the plan drawings until you are familiar with the assembly and fit. Sand or plane any edges that cause the bulkheads to fit too tightly or require forcing them into position. They should be able to be easily fit into position. (You will not be able to seat the two wheel well mount longerons completely until you have finished the steps below but you will be able to see how they ultimately fit with the other parts and the fuselage.)

Mark the landing gear wheel well opening on the bottom of the fuselage:
With a tape measure make a small mark on the fuselage lower center line 29" from the end of the tail cone. Next, measure and mark a center line on the marking template supplied.

Place the back end of the template on the 29" line and center it on the fuselage center line. Trace it out with a pencil or felt-tip marker and cut out the marked opening with the dremel and cut-off wheel leaving the pencil line to allow for trimming if required.

Test fit the wheel mount longerons in the outer slots you've just cut and trim the opening if needed with a small emory board or file so the parts fit flush and square. Small imperfections can be cleaned up more easily with file and or filler after they are cemented in place

NOTE: You can use the wheel well marking template as a spacer or square to make sure the longerons fit square and parallel to each other and the fuselage prior to proceeding to the next step when they are cemented into position. It is important to check for squareness to see that the axle center line is 90 degrees to the fuselage center line so the wheel tracks straight and to check that the template can be inserted into the cutout which ensures that the longerons will be the right distance apart to freely jig to the other parts.

Total time for step 1 about 30 minutes.
Last edited by mmartin55; Apr 02, 2005 at 11:13 PM.
Mar 28, 2005, 11:36 PM
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I should add that when measuring for the opening location, measure straight line from the bottom edge of the tailcone to the 29" mark. don't follow the curve of the lower fuselage. Note too that the markings are on the outside of the fusleage but picture better through the epoxyglass.
Last edited by mmartin55; Mar 29, 2005 at 06:04 PM.
Mar 29, 2005, 05:36 PM
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NASA Deep Stall/High Angle of Attack

An interesting sidebar from the NASA Dryden web pages on their test program and a ventral view of the ship in deep stall.... Check out the cool markings on the lower wing! Notice too the fact that NASA utilized an RC scale aircraft to test the concept before employing the piloted full-size vehicle (highlighted).

Project Description: In the early 1980s, a Schweizer SGS 1-36 sailplane was modified for the NASA controlled, deep-stall flight program. The aircraft, flown at the Ames-Dryden Flight Research Facility (ADFRF, both before and after that time called the Dryden Flight Research Center, Edwards, California), was used for controllability research in the deep-stall region at an angle of attack of above 30 degrees.

Schweizer modified the horizontal stabilizer (T-tail configuration) so that it could pivot as much as 70 degrees with the leading edge down. Once the aircraft arrived at ADFRF, it was further modified, including modification of the cockpit area to permit easier pilot egress and addition of a NASA instrumentation system in the fuselage. After the modifications were completed, radio-controlled-model and ground tests of the aircraft were performed prior to flight tests. These preliminary tests included use of a simulator.

In September and October 1983, the modified Schweizer SGS 1-36 was flown in the ADFRF's high-angle-of-attack program. The Schweizer was chosen for the program because of its slow speed and because its high-angle-of-attack aerodynamics were dominated by long wings rather than a long, pointed nose or forward strake. The objectives of the program were to demonstrate the feasibility of piloted, controlled flight at very high angles of attack and to refine piloting techniques required to make a safe transition into, maneuver in, and recover from controlled flight at very high angles of attack. Of particular interest during the 20 flights of the sailplane were the stability-and-control derivatives, trim data, and piloting techniques required to safely enter and exit the very high-angle-of-attack flight regime.

For the flight test, the sailplane was typically towed to an altitude of 8,500 feet above ground level and released. Upon release the sailplane was decelerated to near-stall speed. The pilot then performed maneuvers to investigate handling qualities.

Flight data showed that piloting techniques for the sailplane allowed the pilot to safely make entry into, maneuver in, and recover from controlled flight within the 30- to 72-degree angle-of-attack range. Maximum likelihood analysis (parameter estimation) techniques were used to obtain aerodynamic derivatives from the flight test data. These data were compared to a predicted data set derived from wind tunnels. Generally, the agreement was fair to good, but the derivatives were used to refine the aerodynamic database at low and very high angles of attack. Analysis of the flight data was also used to better define the vehicle's trim and operational performance envelope.

The Schweizer 1-36 sailplane is a single-place, mostly aluminum aircraft. The wingspan is close to 46 feet and the fuselage is nearly 21 feet long. The horizontal stabilizer is a T-tail configuration with a span of 7.9 feet. (from NASA)

Last edited by mmartin55; Mar 29, 2005 at 10:55 PM.
Mar 30, 2005, 09:48 PM
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SGS 1-36 Fuselage Step 2


The next step in constructing the fuselage is to prepare all of the parts for assembly of the carry through spar. The carry through consists of two 13/32" O.D. brass tubes which serve as the receiver sleeves for the 3/8" O.D. solid carbon wing rods. The sleeves are bedded in a 1/8" laser cut tabbed and jigged box attached to the main bulkhead, and sandwiched between vertical end grain balsa fillers.

The theory behind the tabs and the extension of the bulkhead and box front beyond the tab slots of the top and bottom caps is to provide more adhesive surface area to the box and prevent blowout of the top and bottom under severe loads.

First trim of the long grain ends off of both sides of the block with your hobby saw. These should remove easily since you are cutting with the grain. Be careful to keep the saw square to the laser kerfs.
Last edited by mmartin55; Mar 31, 2005 at 05:45 PM. Reason: Added image
Mar 30, 2005, 09:51 PM
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SGS 1-36 Fuselage Step 2 (cont.)

Next split the four peices carefully one at a time from the block with the saw keeping the saw square to the laser kerfs to cut away the remaining gates in the cuts.
Mar 30, 2005, 09:54 PM
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Next, lay the main fuselage (wing joiner) bulkhead flat on the table, insert the top and bottom caps into position, and lay the four web fillers in place between the top and bottom.

Insert the length of 13/32" brass sleeve slightly past center and mark the end where it protrudes past the edge of the bulkhead. Mark the sleeves with pen or pencil leaving enough extra material (1/8" or so total) so that the inner ends of each sleeve can be sanded to a 3.5 degree angle and the opposite end will later protrude out of the glass fuselage to be sanded flush later.

Cut the two peices of brass.
Mar 30, 2005, 09:55 PM
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Double post, deleted, tm
Last edited by mmartin55; Mar 31, 2005 at 05:54 PM.
Mar 30, 2005, 10:17 PM
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SGS 1-36 Fuselage Step 2 (cont.)


Next, with the wing carry through assembled as before when marking the sleeves without the front plate in position, trace the location of the edges of the webs and sleeve junction with a pencil then reverse the box and assemble it again on the front plate and trace the same marks on the inside of the front plate.

Using the dremel and a 7/16" burr, make a shallow hollow in the center of each part to allow the 13/32" sleeves to seat and the box to fully jig together. Test fit until satisfactory.
Last edited by mmartin55; Apr 13, 2005 at 05:56 PM.
Mar 30, 2005, 10:29 PM
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I will put the 2.5 degree bevel on the inner joint of the two sleeves on the belt sander in a few minutes and then call it a night. Total time for step 2, about 30 minutes of modeling....

Plus an hour of photo manipulation i.e. sharpening, color correction, resing down, cropping and another hour of writing and rewriting the commentary.

Tune in again tomorrow for Step 3, Drilling the Wing Rod Holes and cementing in the structure.
Apr 02, 2005, 05:28 PM
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1-36 Fuselage Assembly Part 2


OK I'm back!

Here is the 2.5 degree bevel complete on the inside ends of the sleeves. This must be done to keep the adhesive from infiltrating the joint and fowling the joiner rods when they are inserted. I am burring a slight hollow recess in the bulkhead and box front since we are using 3/8" balsa for the veritical grain fillers and the outer dimension of the sleeves is 1/32" over that requiring a 1/64" channel on each side to properly seat. One quick pass with the foredom 7/16" tungsten carbide round burr and its done.
Last edited by mmartin55; Apr 13, 2005 at 06:00 PM.

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