Applewhite 3 Stage Cluster Cone

[JAL3]

A sentimental favorite of mine is the 3 Stage Cluster Cone designed by Art Applewhite. Its a favorite because it is my first successful staged rocket, my first successful cluster and because the interesting stuff happens low enough to where it can be seen.

 

[JAL3]

The Cluster Cone is dependable enough that I used it at an exhibition for kids at the local museum where space was at a premium. The flight was a great success; all motors and all three stages lit off. The two boosters landed in the small courtyard but the sustainer drifted across the San Antonio River, never to be seen again.

For a year now, I have been meaning to replace the sustainer. I finally gathered the boosters, tossed them into the back seat and brought them home, making several stops along the way. There they sat for a while. My wife borrowed the car and moved the seat all the way up. I moved it back where it belongs and headed to the lab to work on the Cluster Cone, among other things. When I got there, I found to my horror that it had fallen to the floorboard and that I had ruined the 2nd stage when moving the seat back.

 

[JAL3]

I had not damaged the first stage booster but it was showing some wear and tear from previous flights.

I decided a complete overhall was in order.

 

[JAL3]

Since the rocket and I were at the shop and the printer and template files were at home, I naturally started with the 1st stage. The only real problem was some scortching due to the second stage ignition. I was pretty firm in my desire to keep having the second stage ignite on demand so I decided to try and protect the 1st stage.

This rocket is not a high performance model. In fact, for what it is used for most often, exhibition, low performance is a plus. I decided that a bit of extra weight would not be a problem. As such, I mixed a batch of 15 minute epoxy and brushed a coat onto the top of the forward bulkhead. It did not add all that much weight and my hope is that it will provide something of an ablative surface for future ignitions.

 

[JAL3]

I still haven't gotten around to rebuilding the 2nd or 3rd stages of this one but I actually flew the 1st stage booster by itself yesterday. My club had an informal D powered spot landing contest and I figured it couldn't hurt.

Instead of using a cluster of 3 motors, I just used a single D11-P.

It Worked!

It actually came in 2nd!


A vid can be seen here: https://www.flickr.com/photos/23694991@N03/3626181029/

 

[JAL3]

When trying to remove the motor from the last flight of the first stage booster, I found that the motor tube were coming loose and that the torque needed to remove the spent casing just about tore things to pieces. When I got it back to the shop, I gently removed the tubes and got to work putting them back in securely.

 

[JAL3]

Some epoxy was mixed and brushed on the interior surface of the forward bulkhead of the booster and along the edges of the fore and aft holes. The tubes were then inserted and the central one seated in its hole. The remaining epoxy was brushed around the rear projections of the tubes through teh aft bulkhead.

 

[JAL3]

After a long hiatus, I finally got to work or the rest of the overhaul of the cluster cone. Work started by printing out th vaious pieces for the middle booster and sustainer.

 

[JAL3]

The sustainer shroud was carefully cut out with scissors and then a razor knife was used to trim things more neatly and cut the lug hole.

 

[JAL3]

The shroud was then drug across the blade of some scissors for a while to impart a bit of a curve.

 

[JAL3]

White glue was then used sparingly along the tab and the cone was rolled into place and held with a clamp.

 

[JAL3]

The after bulkhead of the top stage was also located and cut out.

 

[JAL3]

The line indicating the fold was then scored by running a pencil over it. This was to ease the folding and ensure the fold occurred along the correct arc.

 

[JAL3]

The bulkhead was drawn along a scissors blade to induce some curl and was then coaxed into its folded conformation.

 

[JAL3]

White glue was then sparringly applied to the tab and it was glued into place. A small clamp was used to hold it in position.

 

[JAL3]

The second stage shroud was something that had been drawn in a CAD file. It was printed out on a tabloid sized piece of paper.

 

[JAL3]

A glue stick was used to cover the back of the printout which was then pressed into place on a piece of poster board.

 

[JAL3]

When the glue had set on the top stages, the clamps were removed.

 

[JAL3]

White glue was smeared around the outside of the after bulkhead and then it was inserted into the shroud, using a section of rod to keep the lug holes aligned.

 

[JAL3]

The almost, but not quite, finished upper stage was put in the booth and sprayed with yellow. It got two light coats but will need a third to fully cover the toner marks.

 

[JAL3]

The astute observer will have noticed that I had not put a motor tube in the 3rd stage. That is because it calls for a paper wrap tube printed from the same cardstock as the rest of the rocket. I found that to be problematical and decided to replace the motor tubes with BTs of the appropriate size. For the 3rd stage that was a BT5. I printed out the sheet for the plan's motor tube to use as a guide and marked the distance off on a piece of BT5. A mandrel was then inserted and the tube was cut to length.

 

[JAL3]

A dollop of white glue was then put in the interior apex of the cone, both to seat the motor tube and to form a protective barrier for when non-plugged motors are used. A ring was also applied around the aft end of the motor tube and it was inserted into its hole and pushed home.

I did clean up the glue on the interior of the motor tube that ran.:eyepop:

 

[JAL3]

My memory of the original build was that the second stage was the hardest. My memory was right.

The first step was to cut out the shroud and get it trimmed.

 

[JAL3]

Pressing down hard, I ran a ballpoint pen along the lines where the shroud would have to be folded. The template was then peeled off and the shroud was bent to form the main folds.

 

[dwmzmm]

I saw Applewhite launch his prototype at one of the Alamo's club's launch back in the summer of 2004; was an excellent flight!!

 

[JAL3]

I saw Applewhite launch his prototype at one of the Alamo's club's launch back in the summer of 2004; was an excellent flight!!

I like to rub it in when I see him that mine has a better record for staging and cluster ignition.:neener:

Art doesn't get to too many of our launches any more and is missed. He's a great guy. The last time he did come, I launched the cluster cone and all 3 stages landed in a straight line, equidistant from each other with minimal walks. I'm still trying to figure how I pulled that one off.

 

[Crazyrocket]

John, I've got a question for you. I made the cluster cone several years back and have had some success in getting the 3 stage to light. On the top cone, I extended the bottom edge to cover the second stage more (to prevent it from falling off). In addition, I tape together the middle stage and top stage motors in an attempt to keep them together. I have about a 30% success rate in light all three stages. How do you set up your rocket to get all three to successfully stage? Thanks.

 

[JAL3]

John, I've got a question for you. I made the cluster cone several years back and have had some success in getting the 3 stage to light. On the top cone, I extended the bottom edge to cover the second stage more (to prevent it from falling off). In addition, I tape together the middle stage and top stage motors in an attempt to keep them together. I have about a 30% success rate in light all three stages. How do you set up your rocket to get all three to successfully stage? Thanks.

I've never had a problem with the top stage falling off. partly that is because of the way the motors are held together. They form a rigid unit. The 13mm fits inside of the 18mm and the 18mm fits inside of the 24mm. I insert the motors into each other and then slip the motor stack into the top stage. From there I slip on the second and it is held rigid. The bottom goes on and then I pack the side motors.

That's the way Art recommended and it has given me no problems. I never would have thought of it myself.

 

[JAL3]

I should have mentioned in my last post dealing with forming the second stage shroud, that I did the folding but did got glue it into place. It was for me, a tedious and frustrating exercise and I decided to put it off for a bit while I did something more agreeable. I went with the forward bulkhead of the second stage.

It was cut out and curled around the edge of a scissors blade.

 

[JAL3]

White glue was then applied to the tab and it was held in place with some clamps to dry.