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NARAM-41 Shuttle model

Model Photographs by Alex Seltsikas

NOTE: This model also flew at the 2000 and 2002 WSMC's

To: NARAM-41 Model Description & Flights

The model built for NARAM-41 was STS-47, which flew September 12, 1992. It was the second mission by longtime NAR member Jay Apt, and the only shuttle launch that George has seen.


Static Judging

Red circle shows where two "hidden" 1/32" holes for Flight Computer Power and Ejection "Remove Before Flight" pins are inserted. Orbiter uses similar method, 1/32" hole inside of a circle of a decal.

On C-rail with "Remove Before Flight" pins inserted. Attachment to base of C-rail, jutting horizontally, includes a 1/8" rod that goes inside a hole in the ET aft dome to press on a liftoff detection switch.

Liftoff on F25 motor

Information on the NARAM-41 model:

The model was built over a 2 month period starting early June 1999. The technical details were mostly the same as for the 1998 boilerplate, except for no attempt to add an A3 "staging" motor mount to the orbiter.

Orbiter construction was similar to the 1984 orbiter - a balsa fuselage, wings, and body flap, with a vac-formed nose section. However the vertical tail (rudder) was vacuum formed, not balsa. Other details included OMS pods (mostly vac-formed, with hollow-cast aft thrusters and OMS engine nozzles), vac-formed heat shield domes, and hollow-cast SSME's. The vac-formed and cast parts were painted, many as fully painted and decaled sub-assemblies that were added to the orbiter at NARAM, such as the OMS pods, and the plug-on vertical tail (rudder) assembly. The balsa parts were covered with Towerkote, an iron-on model airplane covering. The Towerkote left a bit to be desired due to some minor wrinkling in spots that was too scary to attempt t o iron back out from fear of making things worse. The orbiter nose and rest of the orbiter was masked off to allow for first painting the vac-formed nose gloss white, then masked further to apply flat black to the front portion of the nose and underside of the nose. The side portions of the nose were not painted black, instead once the paint was dry enough to do decaling some solid color black decal sheet was cut to shape and applied. The nose thrusters and other black portions of the nose section were mostly reproduced by using some decals I drew up which were printed by Tango Papa Decals (examples shown at right at 2X or 1/36 scale). The custom drawn decals also included the orbiter cockpit windows, overhead windows, aft T-0 umbilical plates, and gray circles for the aft OMS thrusters. Remaining portions of the nose and wing glove section had pieces of black decal cut to the necessary shapes and applied. The black hinges along the bay door sills were simulated with black adhesive trim Monokote, which was applied by team member Jay Marsh. The remaining "markings" on the orbiter were from the 1/72 decal set made by RealSpace Models. After all the decals were applied and dried, the orbiter was painted with Model Master's clear flat lacquer. That's when it transformed to look "real", up to that point it was shiny white Towerkote, shiny black Towerkote, semi-shiny black solid color decal, shiny white paint, and flat black paint, once the flat coat dried then everything was uniformly flat white and flat black, and the clear film around the edges of the decals didn't appear either. The last parts put on were the main engines, which could not be added till after the flat coat or they would have lost their metallic appearance.


The External Tank (ET) was also much like the 1998 boilerplate ET internally. However to cut mass it used a fiberglass body tube, made by Jay Marsh. The ET aft dome, which before either was not on boilerplates or used a vac-formed copy of the inaccurate NCR kit aft dome, was to the correct shape thanks to a wooden vac-form mold turned by Jack Hagerty. Also for the first time the intertank was simulated fairly accurately, thanks to a laser-cut pattern made by Tom Campbell. The cardstock lasercut pattern was used as a master to produce an RTV mold. Then the RTV mold was used for creating epoxy/fiberglass wraparounds (the pattern was for 180 degrees so two were needed). Additional detailing was added, some by making RTV molds of Monogram shuttle kit parts then casting the parts, others by building up from scratch (such as the pipe/conduit strips). For the orbiter separation sensor, a very small microswitch was mounted into the Lox line where it enters the orbiter on the real thing, the switch pressed down by the orbiter until it seps. The wiring was run up inside the Lox line all the way to the intertank. For painting, a spray can type of Red Oxide primer by Wal-Mart turned out to match the colors of this mission. For the lighter yellow-orange color of portions of the tank, "Daylight Orange" by Polly-S was airbrushed onto separate parts before final assembly (in retrospect it's a bit too orange). For other areas where it was not practical to paint the part separately, particularly the bands along the top and bottom of the intertank and a band below the "beanie cap" on the ET nose, white decal sheet was airbrushed with the Daylight Orange color then portions of the now solid color Daylight Orange decal sheet were cut to shape and applied. Pieces of the orange decal were also used on the simulated support brackets of the pipe/conduit lines.

The ET nose was similar to the boilerplate, vac-formed using an old NCR shuttle balsa ET nose as the master pattern, except this one had added detailing and the need to hide the flight computer power and ejection arming remove before flight pins. On the boilerplate no attempt was made to hide them, using regular 3/32" phone jacks. For this model, small lever switches were built into housings so that a 1/32" pin could be pressed into place to hold the switch lever down. The orientation was chosen so that acceleration (or deceleration) on boost would not cause the lever arms to move once the pins were removed. This approach allowed hiding the holes for the remove before flight pins between a pipe and conduit strip running down from the ET nose. It is visible in the photo at right but it seems the judges didn't notice. The Orbiter used a similar method, with its 1/32" hole aligned with a 1/16" hole in one of the RealSpace Decals.

The SRB's also were technically the same as for the boilerplate, except for the use of fiberglass tubes made by Jay Marsh. The SRB's used the same kind of wind-up timers for recovery system activation. However the fins were different, instead of plywood glued externally, the NARAM model SRB's used .06" Lexan fins, with a 7/8" long tab glued inside the vac-formed aft skirt. It is not easy to tell in photos but the portion of the fin ahead of the aft skirt is not attached to anything, it parallels the side of the body tube with about a 1/16" gap. Only with fin material as sturdy and strong as Lexan, particularly .06" thick, can such a trick of using just a tab be acceptable structurally and for the not-too-high flight loads (this does come at some price, notably higher fin mass, and even Lexan could snap given such a relatively small tab). Details such as the hold-down struts, aft sep motors, and the forward portion of the system tunnel came from using the Monogram kit parts as masters for RTV molds and casting with Alumilite. The systems tunnels themselves were 1/8" wide half-round from Evergreen scale models. The SRB noses were hollow-cast from an RTV mold based on the Monogram kit. The "hollow-cast" method used for those noses and the orbiter SSME's was the slush-cast method, where a small amount of resin (with some microballoons in this case) is poured in, the mold rotated around horizontally cement-mixer style to coat the mold inside, then pouring out some excess and continually rotating the mold by hand until it sets up stiff enough. With a fast-curing resin like Alumilite that is practical, anyway, but does take some time and trial and error to master the technique.




SRB painting involved first using white primer to get the tubes smooth, then after applying external parts using another coat of primer before going to gloss white. Krylon white primer and gloss white was used for those purposes, not as fine as some other paints but having had some painting problems earlier in the year on the X-20/Titan-II I went with what was reliable in the past. Actually first I had tried to use just gloss white on the tubes and found that the fiberglass tubes really need to have a primer, some discussion with Bob Biedron and Jay Marsh showed me how silly that idea had been to not use primer. There was no paint other than the white, but the SRB's are not just white. On several missions, the SRB noses had a complex series of markings, which are no longer used. But I liked them, gave the shuttle a bit more of a complicated look even if it was just a little black paint. On this model those markings were done by using black decal material, cut to shape. A pattern was drawn up for the three different shapes, and after tweaking to get the size and shape just right, the printed patterns were rubber-cemented onto the black decal sheet, then the patterns cut out. After cutting, the paper pattern was peeled off from the black decal, thanks to the rubber cement. The decals were applied using a good amount of setting solution to make sure they snuggled down into the ridged surfaces of the SRB noses. Some round decals for the noses were cut out of black decal by sharpening the end of the correct diameter of brass tubing and using a small mallet to punch them out. Same was done using some silver decal material to punch out small round silver dots to apply over the locations of the separation rockets on the nose. Red decal was used for the strip on the lower portion of the nose. More black decal was used for the upper part of the SRB tubing, and some white decal, 3 layers thick to increase opacity, was used to simulate the access panels near the top of the SRB's (Yes I know those should be slightly recessed...). The various bands on the SRBs, including the field joints, were simulated by using different widths of black and white striping tape. No attempt was made to achieve the 3-Dimensional shape of the three lower stiffening rings which include the foam ramps. The foam ramps were simulated by the same orange decal material as used on the ET (thanks to Jay Marsh for applying those at the last minute plus Dave Faulkner doing "super soaker" duty). The SRB nozzles were vac-formed, and painted a tan color. They were attached to the SRB's last, using a Hobby-Tac contact cement that has interesting properties of a contact cement while not attacking paint, almost like a cross between contact cement and rubber cement. The same Hobby-Tac contact cement was used to attach the SSME's to the orbiter as well as a few small details to the ET.

The whole model never was together until minutes before taking it to turn-in Monday night. Ed LaCroix brought in the neat display stand he made up, freshly painted black. The build-up process began with putting the ET onto the stand, then the SRB's, then the ET nose, and finally the orbiter.

The Flights

As some of you know, the first flight did not go well. It took off OK, flight path was OK, even sepped the SRB's OK. But from there things went badly.

There were about 3 separate problems on the first flight it seems, and of course none had cropped up before in the 9 previous flights of the 1998 version boilerplate the NARAM model is based on. First was the ET nose came off shortly after the flight computer commanded SRB sep. The ET nose had been a bit loose and now I know it was too loose. That is a major problem for this since the ET nose has 6 wires connected to the main ET by means of a 6-conductor telephone jack/plug set, and when the nose came off it no longer could "see" orbiter sep that the computer uses as a key event to fire the ejection 1 second later. But the programming is supposed to fire the ejection if the orbiter is "late" in separating, there's a 4 second window from computer-commanded SRB sep to sep the orbiter by R/C. I do not know at the moment if the programming did not account for that condition or something as basic as the computer battery also going out about that time. So in any case it was fortunate that at least the ET main chutes got yanked out, since all the chutes are stored tightly in about 4" of space in a BT-80 in the ET nose (chutes meant to be blown out rearward by a piston when an electronic ejection charge goes off). And it seems the ET nose chutes got out (?) but didn't deploy, which if that was the case is a totally separate and screwy problem if both were out and both failed to deploy. Again, have to check video footage.

The last goofy thing was that the orbiter didn't sep when commanded by R/C. I later found there was a problem in the programming I did in the computer transmitter where the transmitter's landing gear switch position affected the throw of the sep servo, I didn't realize the gear switch was in the chain of the programming (in other words I had needed to disable the gear switch from a default setting and overlooked it). To do the actual separation I flip a different switch, a boost/glide master switch, which is programmed to not only sep the orbiter but to change values for throws and to change the elevator trim for "uptrim" for glide). Considering that the orbiter never sepped, and it is not known yet why the computer didn't cause ejection once the allowed orbiter sep window expired, it might have been fortunate after all that the ET nose came off and at least got the ET main chutes out. If the ET and orbiter had plummeted down, there would have been little more than two SRB's left from that model.

The ET main's chutes were not meant to bring the ET and 240 gram orbiter down together at the same time, so not only was the landing rough on the ET, bashing in the vac-formed aft dome, but also rough on the orbiter (which of course was not intended to "back into" the ground). The body flap was knocked off, one OMS pod popped off, one of the main engines was damaged, and a balsa spar inside the vertical tail (rudder assembly ) was cracked. Also one of the elevons was bent upwards by 10 degrees, fortunately it was possible to bend it back (The brass rod used as a torque rod on that elevon was bent).

Jay Marsh and I set about doing repairs. There were a few moments during the attempt to get it ready to fly again that it looked like it might be "game over". Foremost was the flight computer. It was not responding at all, and considering the ET nose had crashed then it was looking like the computer was damaged. Jay carefully checked it over to try to pinpoint the problem. Fortunately it turned out to be that the 50 mAh 9.6 volt nicad pack was bad, one of the solder tabs must have broken loose when the ET nose hit. Fortunately there was a back-up wiring harness to plug in series two 4.8 volt 50 mAh packs as used for R/C RBG's. So, the computer "took a licking but kept on ticking" (didn't hurt that it was mounted inside a hardened "capsule").

Also for awhile the aft launch lug was missing (not known if it came off at launch or landing). The model is C-rail launched and has to have two lugs. If it had not been found then then it was likely the remaining upper lug would have been cut two halves and gluing one of the halves to the bottom. Good thing it didn't come to that.

The ET/Orbiter attachments were also of concern. The two 1/16" brass pins that go perpendicular from the ET aft struts inside the orbiter to transfer the acceleration (push) loads to the orbiter were broken away forward, the cast struts had cracked along the 1/16" holes the pins were mounted into. Fortunately those were fixable by applying thick CA. Various other repairs to other pieces too, mostly minor. It was at least fortunate that no key part was damaged, or damaged beyond repair - there are some pieces where there is no practical field repair possible if they break, like an aft SRB/ET attach strut....."game over".

Finally it was all fixed and ready to fly again. It pitched a little bit off-vertical but not too badly, and shortly after burnout the computer sepped the SRB's. OK, that's where flight 1 stopped going well. This time, ET nose stayed on, and the orbiter/ET coasted along for about 2 seconds then I commanded orbiter sep and it came off cleanly, right into a glide (unlike the 1998 boilerplate, this one was not built to "stage" by firing an A3 in the orbiter at orbiter sep).

Now glide was the part of the flight that was a big question in the previous months. There never was any opportunity to check the glide trim of that new orbiter (Well, if I'd really wanted to I would, but it's too big a risk to do with a "real" scale model) . The best that could be done was to try to build it to be aerodynamically the same as the boilerplate orbiter (built in 1984, 15+ years before), and get the glide CG just right...if it was 1/4" tail-heavy it would not even glide but "mush" like the real thing does during re-entry. So, would it glide? Would it be controllable? How much trim would have to be dialed in during a glide that was going to last 20-25 seconds? As it turned out, the CG was just about right, and the elevator trim was about right. It did pull a bit to the left, but rather than try to add right rudder trim I just flew it and held a little right stick. Made one large sweeping turn , it had separated and gone into a glide pointed downwind, so I turned it to the right for a 180 degree turn and the landing was into the wind, about 150 feet or so from the contest range. Everything else worked, SRB's deployed their chutes, ET deployed main chutes and ET nose deployed its chutes (dual chutes everywhere). Qualified flight, easily taking first place in Team Division

It was a great relief to have it work, and a lot of excitement too. As I said at the banquet, some people asked me how long it took to build the model. One answer is it took two months, but another answer is it took 22 years. Many of you know I've made shuttles and orbiters of one kind or another thru the years, some for fun, some for boilerplates, but none for contest flying. Indeed the first orbiter, a very crude free-flight 1/80 piggyback orbiter, was built 22 years ago, the day after the first Enterprise ALT flight. This is eerie, I checked some resources and see that Enterprise's first ALT flight was August 12th, 1977. So I built my first orbiter August 13th, 1977. The NARAM-41 shuttle flight was EXACTLY 22 years later....

The second flight didn't cause any significant new damage. The ET nose had extra tape added to the shoulder to make it a tighter fit so it would not slip off. And as it turned was too tight. For the first time since using Jay's flight computer, on flight #11 (9 boilerplate, 2 NARAM model), the back-up ejection charge also fired. The back-up charge is fired 1/2 second after the primary, on a good ejection the back-up charge is unplugged as the ejection piston is blown out. Since the 2nd charge fired then obviously the first charge didn't eject the nose fully or at least didn't blow the ejection piston out of the ET nose.

Looking to the future, the orbiter damage can be fixed by replacing some removable sub-assemblies, like replacing the cracked main engine. The ET though needs to have a new aft dome added which will be a not-fun affair to replace a part meant to be permanently glued. But it sure beats building a new ET. The ET nose will have to be replaced, it's vac-formed shell was cracked and while flyable it's judge-worthy days are over. But the ET nose is the one "big" part of the model that is the easiest to replace, I'd rather replace the ET nose (long as the flight computer didn't have to be replaced too) than say the orbiter's removeable vertical tail (rudder) which has far more time invested in it than most people would think.

Jay Marsh entered the flight computer project in R&D at NARAM. The computer was originally built for his Saturn-IB models, but is basically the same as used for the shuttle model, just different programming. He was going to make a demo flight for the R&D judges Friday at NARAM but they told him it wasn't needed and given the trees and wind he chose not to fly. But the shuttle model happened to serve as an unofficial demo of the computer. In any case, Jay's flight computer won R&D at NARAM in Team division.

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