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X-1 Scale Model
R/C Rocket Boosted Glider

 Built July, 1997    1/10 Scale

This is a 1/10 scale model of the X-1 flown by Chuck Yeager to break the sound barrier on October 14, 1947. For more info on the X-1, chck the Dryden X-1 History page, Wikipedia X-1 page, and the NASM X-1 exhibit page.

The X-1 R/C model was built from balsa, has a 30 oz liftoff mass and 25 oz glide mass. Boosts on 32mm F13 or G12 reloads. Burnoff of propellant mass in the tail is countered by water ballast dumped during boost and first seconds of glide to keep from being too nose-heavy in glide. Aileron for roll control and moving stabilator (elevator) for pitch control.

See Text description, Drawing below, and Photos for more info.


After landing, Oct 14, 1947
X-1 at NASM in Washngton, D.C.

X-1 model at NARAM-39

Photos on this page are clickable thumbnails except for the above N-39 compilation

X-1 Assembly Drawing
X-1 with decals drying at NARAM-39

Photo by Alex Seltsikas

Flight at the Mick Wilkins Regional at NSL-99
(Greg Warren pics above)

Assembly Photos
X-1 Assembly

OK, so my model was not THIS hard to build.
but it it interesting to see the separate nose,
mid-body, and tail section as I built mine.

X-1 Nose Frame with water tank in front

After remaining stringers were added, 3/16" "plank" strips glued down across stringers. See drawing for more information.

Wing, framed nose, and mid-body

A "dry fit" of part sub-assemblies. Note plug-in spar at root of right wing, and the hole for spar tube in the left wing root area.

Wings plugged into mid-body

Wings were made removeable for transport. The upper part of the mid-fuselage was nto sheeted untl after the whole fuselage was completed and the pushrods were run to the cockpit area.

X-1 Fuselage parts

Wing center section is attached to mid-body. Tailcone made of 3/32" balsa sheet rolled wet. Tailcone slightly oversized at wide end with extra layer of balsa inside to allow for sanding down the sharp break of the mid-body-to-tailcone joint to a curve.

There are More Photos Near Bottom of thePage


What follows is a description of the building and the flying of the model. See also the assembly drawing which is on this web page and the pictures of the nose assembly and fuselage subassemblies above.

The X-1 model has a scale factor of 1/10. Diameter of 5.4", length of 37", span of 36", Wings just a bit bigger than scale, for a wing area around 165 sq in (150 would have been scale).

All-wood construction. Nose section built-up using round formers and 24 stringers, with 24 3/16" balsa "planks" glued across the stringers. The 24-facet cross-section was sanded to a round cross-section. Center fuselage also built up, but a very simple frame with bulkheads, skinned by 1/8" balsa curled to shape. Rear section was a straight cone made up of 3/32" balsa curled similar to how paper & cardboard transitions are made. Some 3/16" balsa was glued inside the lip of the slightly oversized large end of the tailcone so when sanded down there was a 2" curved transition instead of a sharp break. Not quite the right rear fuselage shape, but practical and light.

Wing was also based on balsa construction, with 1/16" wing skins, and using a Bob Parks BP-3d airfoil. The wing had a 5.75" span center section that glued into the fuselage mid-section, the outer panels of the wing plugging into the center section using telescoping fiberglass tube joiners and music wire alignment pins.

Wing control surfaces consist of what were flaps on the real X-1 (going out about half-span from the root). On the model, those flaps were used as flaperons, moving both as flaps and as ailerons. More recently the flap capability has been taken out, they act only as ailerons.

The horizontal tail section was built to be all-moving, a "flying tail". That simplified making the tail removeable for transport, slipping the two halves and their joiner rods from the bellcrank inside thehollow fin/rudder assembly.

Power by 32mm reloadable motor, as used by the Aerotech "Phoenix" Rocket Boosted Glider. For G12 and F13 power. Might do an F16J someday but the endburners are more my speed.

The burnoff of the propellant would cause a VERY significant shift in the CG due to the far aft locaiton. To compensate for this, a vac-formed water ballast tank was added as far up front as possible. It held 90 grams of water. With a fill/drain line and a vent line. At liftoff the drain line came unplugged to allow the water to drain out by gravity-feed. Tank is fully drained about 4-6 seconds into positive-G glide after a G12 reload.

Final details of the model were that the upper and lower ventral system tunnels were made out of vac-formed plastic. The finish of the model was primarily by using orange Towerkote iron-on covering. The lower ventral tunnel was painted using a color-matched paint by Monokote. I wish I'd painted the upper tunnel too, as the Towerkote produced some bubbles that would not go away.

The big Stars & Bars markings were mostly cut-out trim monokote, plus some red decal stripes that Ed Lacroix added. The decals for "Glamorous Glennis", "Bell Aircraft", and a few other markings were done in MacDraw (much traced from scans of X-1 kit decals Alex Seltsikas did for me) and color printed. The color print then was used as a master in a color xerox machine to print onto some high quality clear water-decal film tom Campbell gave me info on (From Micro-Mark). Obtaining the decal material and printing them was described in more detail earlier this week in the thread about how to make decals.

The model's mass turned out to be around 30 ounces in liftoff mode on a G12, 25 ounces for glide (5 ounces lost by water dump and propellant burnoff).

Now, when I planned building this a few months ago, it was going to be "for fun", to sport fly at NARAM. But part of the way through building it, I started to think about entering it in sport scale at NARAM. It actually was a dumb thing to do if our team wanted to score well, the Little Joe II has a good track record, while the X-1 would not score well in static. But in helping to run NARAM this year, our team wasn't flying as "seriously" as we usually do. Ed LaCroix agreed it seemed like a neat thing to do this year, so we decided to use that for Southern Neutron's sport scale model after all.

Indeed it didn't score up there in static, 5th place.

On to the flying. Ed LaCroix assisted getting the bird ready to fly from the tower, as we loaded the water ballast, plugged in the battery pack, and popped the canopy in place. At launch it took off out of the tower straight. But it had a bit more up trim than it should have, it pitched up near vertical and I had to use full down to keep it from going beyond vertical onto its back. It also had a roll that I let go while working the pitch control . Finally settled down into a glide, as it stalled somewhat due to the trim still being off. Got it sort of trimmed, and also trimmed out a roll to one side. Finally ready to land, trying to land on a real dirt runway at the NARAM site. Coming in just fine, then put the flaps down and... it pulled to the left. The flaps didn't deploy symmetrically. Landed safely, but missed the runway.

OK, so it was planned to be one flight. But that flight wasn't satisfying. So, quickly it was ready to fly again. This time with downtrim added, and aileron throw reduced (it had been sensitive in roll on glide). The launch was very smooth, as though on rails. Pulled a bit of up to bring the final climb angle ot around 60 degrees, and corrected a bit of roll. So it was a very smooth easily controlled boost. Altitude was around 500 feet. Never even felt the difference when the last bit of water ballast drained out, it felt good in glide off the bat. Still a bit sensitive still in roll during glide, so I went back to the boost low rate for aileron throw. Did at least one very large racetrack pattern, maybe two, before going to the far end of the runway to set up for landing. Got there with lots of altitude, so did a couple of 360's to burn it off, might even have been able to use a 3rd. Got it on line and came in to land... and it kept on going. Had expected to land 50-100 feet in front of me, but it flew 50-75 feet past (flaps would have helped there to shorten the slope but after the first miscue, they were not going to be used for the 2nd flight). Fortunately landed on the dirt runway anyway... but not with much room to spare. No idea of the glide time, just it was a lot of fun (once it finally got into the air).

It scored some nice mission points, moving it past the previous 3rd and 4th place static models. Unfortunately, the 1st and 2nd place models, John Pursley's (Jekyll & Hyde Team) huge Saturn-V (around 1/66 scale, 60" tall), and Mark Bundick's (All the President's Men Team) nicely built Atlas-II both crashed, so the X-1 ended up taking 1st place in the Team division.

The model flew 7 more times in 1997, 3 at Muncie (US Team flyoffs 1997) and 4 more at a later Birmingham Tripoli launch. One of the flights was timed, for about 2:15, though that was probably with a bit of a thermal assist.

It also flew at the Mick Wilkins Memorial Scale Meet, held during NSL-99 in Ardmore Alabama. It took first place in Sport Scale.

Sadly, the X-1 literally crashed and burned at NARAM in 2000. The take-off was unusual and I tried to do a loop to get it to enough airspeed to be controllable, but it hit the ground a glancing blow, knocking the G12 engine mount loose. The still-thrusting G12 caused the balsa tailcone to burst into flames. Everything aft of the wings was destroyed in the fire. It might be rebuilt someday.

First X-1 Model: 1984 (approx. 1/14scale)
First X-1 Model in 1984 only lasted one flight! It was about 1/14 scale, boosted on an F15


The Ejection made the entire tailcone blow apart. It took 13 years to return to the project and buitl a new one.

1/10 scale model first flights - NARAM-39 in1997
Preflight prepping with Ed LaCroix


Model during boost

Gliding along


Relief that it worked, and moved from 4th to 1st place!

NARAM-42 in 2000 - Literally Crashed and Burned

The X-1 in the Scale judging room
at NARAM-42.

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Model got off to a bad start. Tried to loop it but it hit the ground a glancing blow.

The G12 was knocked loose when it hit, and thrusted inside of the balsa tailcone. The tail cone burst into flames

Everything behind the wings was burned. Maybe some day I will rebuild it.

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