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Astron Space Plane R/C Models

 
First three Estes kits,
including Space Plane

The first successful Rocket Boosted Glider was John Shulz's original Space Plane. But it was not suitable for most people to build and fly successfully, so it was redesigned by John Shulz and Vern Estes into what became the first Boost Glider kit, and Estes Industries' third kit (see bottom of photo at left). That was the Astron Space Plane, Kit K-03, in 1961. You can find plans for the original kit on Jim Z's Rocket Plans site.

In 1964, John Shutz and Vern Estes were awarded a patent for their "Model Rocket Glider". See photo at right. The photos at left and right were taken in Vern's rocket history room in 2000 (NARAM-42).

You might be interested to check out Vern Estes' website. The articles page has a link to a PDF article in Air & Space Magazine, "Mr. Estes Comes to Washington", which among other things includes mention of the Space Plane and great photo of Ven with four old models - Vern holding being the original Shutz design and in the background the version that became the Space Plane kit, plus a Scout and original Big Bertha.


1964 Patent

 
Space Plane
in Estes Catalog


Space Plane Repro
Kit by
Semroc

 

For NARAM-50 and the Old Rocketeer Reunion this year, I wanted to make something interesting based on an old model from the early days.

Since I like Rocket Boosted Gliders, I wanted to do a scale-up of an old glider design. Finally settled on the Astron Space Plane. Planned to also fly that in the Imagination Celebration at NARAM.

Of course I wanted it to be R/C, as I had done with the SkyDart 2X project. For this one, I decided to make a very simple easy 2X prototype, and see how it flew. If I liked how it flew, then I might be able to justify making a larger one. The 2X scale made the wingspan about 17".

Note that all photos on this page are thumbnails, click on them to see larger images.

 

Astron Space Plane 2X

Built May, 2008 

The 2X size was good for a model that could fly on just a C6 engine. It is not a dead-on scale model, a few things were tweaked. A BT-55 would be close to 2X size, but the ultra micro servos required having the tube just a little bit larger. So, I used some Quest 35mm tubing. I had some left over from the NARAM-48 Quest Kitbash, the tubing was red and the nose cone was red, so that was a nice match.

The servos were small enough to glue bottom-to-bottom, with their output shafts sticking out the side of the 35mm tubing. To get the servos in, first I had to make the proper size holes in the tubing for the output shafts to stick out thru, then squeezed the tube into an oval so the servos could be slid into place. You can see in the middle photo below how the left side servo output arm sticks out, connected to a pushrod that goes to the left elevon.

The wing was simply 1/8" balsa. The elevons also 1/8", but from a bit stiffer and heavier piece of balsa. Also, the whole elevons were covered with red Monokote to stiffen them against twisting. The Monokote was also used as a hinge.


Vern Estes (right )
& George at NARAM-50.
Vern is holding a
Golden Scout kit.
Photo by Tom Beach
    
Ont the pad, using 3/16" rod


Space Plane 2X model


Shortly before the first flight

 

 

The rudder tips were made in two parts so that the grain could run the optimum way to prevent breakage, and a strip of spruce added to the trailing edge of each rudder to strengthen it.

A micro whip antenna was used internally, with a Berg Stamp receiver. For power, a 2 cell 90mAh 7.4V Li-Poly battery pack running off of a 5 volt regulator.

Each servo drives an elevon directly. The transmitter does electronic mixing so that pitch and roll (elevator and aileron) control is commanded to the servos to drive the elevons.

The 2X model was flown at the BRB May launch. First flights were on B6-2 engines. I figured it would be too twitchy to try to control on boost like most other R/C RBG's, so I gave it full left aileron at launch to make it roll on boost. However, it still pitched lot at liftoff. I used up a number of B6's dialing in the correct amount of elevator trim for boost, and increasing the aileron throw for boost to make it roll more. Finally got it worked out, and went to C6 power.

It turned out to behave VERY nicely during glide. R/C control of it was very easy, and the response to the R/C control was very good. It flew so well that it should make a nice addition to the "demo fleet" when we go do rocket flight demos at schoolyards that are too small to risk some of the larger models we'd like to.

 Astron Space Plane 4X

Built June, 2008

 

 

The 2X flew so well, that confirmed the idea of making an even larger one for NARAM. I wanted it to be able to boost on a G12 reload. After working out some numbers and weighing some components, I settled on a 4X model. With a span of nearly 34", and using a BT-80 body tube. Similar layout as with the 2X model, just twice as big.

The wings were solid 1/4" balsa. I figured this one needed to look "pretty", so I decided to use Towerkote on the whole wings rather an leave them bare balsa. When I ironed on the Towerkote on the first side of the left wing, the wing got warped, badly. I worried for awhile the warp might not go away. But after covering the other side, I was able to get it all flat again.

The rudder tips were 1/8" balsa. With some basswood strips laminated to the full length of the lower rudder's leading edge curving to bottom surface. That was for ding resistance, as well as spruce glued to the trailing edge.


2X and 4X models on pads


2X and 4X models


Ready for the first flight of the 4X

 

 

For R/C gear, a pair of micro servos with plenty of torque to handle this model. A Hitec 555 receiver, and 140 mAh Li-poly 7.4 Pack plus 5V regulator. For the antenna, I replaced the last 36" of the 555 receiver antenna with .020" music wire, and let that trail down from the front , down inside the body and out the back ,trailing about a foot behind the model.

to make it more practical to ship, the body tube is in two parts, with a tube coupler. To fit into the box I found for it, I had to have the joint a few inches behind the start of the wing, so there is a triangular part of the front edge of the wing glued to the removable nose section.

With the engine located pretty close to the glide CG, there was no need to compensate for propellant mass burnoff, such as had to be done with the X-1 model (which used a water ballast tank in the nose). That was one of the other things that the 2X model had proven, even when the 2X model ejected out its engine. For the 4X, the 32mm reload casing would stay onboard.

For the launch rod, simply a spare .505" diameter fiberglass tube as used for tower rails. For a launch lug, BT-5 was too tight of a fit, so a piece of 14mm tubing was used. The 14mm tubing was a bit wimpy, so it was given a few wraps of 3/4 oz. fiberglass cloth and saturated with some laminating epoxy to make it plenty sturdy.

    
Gliding along


Glide photos by Blake Driskill


Landing

 

 

The model was ready for the June BRB launch. Since it was pretty large and sort of heavy, I figured it out not be twitchy on boost, so I did not try to roll it. It took off and just boosted almost like it was on rails. Zero roll, and just a hair of a pitch-down. Was so easy to correct the boost for. That first flight was on an F13, in case the boost was poor it would burn out in 3.5 seconds rather than last for 8 seconds on a G12. But that first test went so well, I flew it several more times that day. The glide handling was even better than for the 2X model. It reminded me of the Zagi Flying Wing that I had converted to Rocket Power, not quite as good of glide but the R/C handling was so good (the dihedral plus leading edge sweepback helps make the roll response very forgiving). Then I put it away to ship to NARAM-50.

NARAM-50 and ORR-3

Late July, 2008


Photo by Tom Beach

At NARAM-50, I was fortunate to get the kind of photo I wanted - Vern Estes posing with the 4X model and myself. Vern was holding one of the "Golden Scout" models flown for the 50th anniversary. Thanks to Tom Beach for the photos. Veneer and Gleda really liked seeing the 2X and 4X models.

On Saturday morning at 11 AM, there was a special launch of old models. I flew the 2X, then after landing changed the model memory in the transmitter and flew the 4X. It took off nicely, but started to roll a little left. I gave right aileron input but it kept rolling left, even more. I was standing directly under it, as it rolled I rotated myself wit it to keep oriented with it, but it kept rolling and rolling. And this was on a G12, with an 8 second burn. The good thing that it was still boosting "up", just in a climbing spiral. A lot of people thought I was doing that on purpose. I did not understand how I could have that much trouble trying to stop the roll. I was almost dizzy when it finally burned out, and I could stop spinning with it. I put it into a glide. I tried to make it turn left.... and it turned to the right. Oh. For some reason, the roll control was backwards, so when it started left, and I gave right, I actually was giving it a lot more left, making it roll more and more left. Good thing it is so stable that it glides free-flight just fine, like it was designed to in 1961. So I did not try to steer it around for a landing close by, I did the minimum to keep it in the general area and let it land safely a few hundred feet away.

Later I realized what went wrong. When I had switched from the 2X model's memory in the transmitter to the 4X model's memory, I had forgotten to click "OK" to actually make the transmitter switch from the 2X to the 4X. And the aileron control is reversed on the 2X compared to the 4X. OK, better it was that which was reversed rather than elevator being reversed, that would have been a disaster.

On Sunday, the Imagination Celebration was held. I flew the 4X two more times.. On Friday, when Scale was flown, we did not have a scale entry so it was a "free day". So, I flew the 4X four more times that day.

    
With Vern at the pad
Photo by Tom Beach

 


Boost - Vern at far left, with Jay Marsh


Imagination Celebration
Note servo arm, pushrod, and Control Horn

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