Rocket #5 - SkyDream (one thru three)

• RDS Thunderbolt
• 78" High, 3" Wide
• 54 mm Motor Mount
• 4.75 lb unloaded at liftoff

Click here for a 2.7 MB MPG of my level 1 cert flight with SkyDream.
Click here for a 1.9 MB MPG of my level 2 cert flight with SkyDream.

SkyDream is an RDS (Rocket Dynamic Systems) Thunderbolt kit. (It's now called SkyDream3, cuz I've had to rebuild the upper body tube twice due to zippering.) Click here or on the image to the left to see a bigger picture of the rocket. I decided I wanted a rocket that was taller than me :-) Actually, I decided to build a rocket that would fly H, I, and J motors so that I could acheive my level one and level two certifications with it.

After the usual consternation and web-surfing to select the perfect rocket, I settled on the Thunderbolt. I ordered one for $87.95 from Rocket Silo on Februrary 27th. I was hoping to get it in two days to build over the weekend so that I could fly it March 4th at Ocotillo. Boy was I overly optimistic. I didn't get it built and ready to fly until March 17th, at SpringFest (El Dorado Lakebed, Boulder City, Nevada).

Construction Details

The kit arrived in good order with all the pieces present. Right away I noticed the effects of the change in scale from my previous rockets. At almost 5 lbs this rocket used heavier equipment all the way around. The shock cord is 20 feet of 3/8" bungee cord. Heavy duty u-bolts and 1/4" plywood bulkheads and fins attest to the different forces at this scale.

I noticed only one problem during construction. The holes for the U-bolts on both bulkheads were too close together. I had to drill them out an additional 1/4" to get the bolts to go in without bending them.

In the picture of the body-tube bulkhead below you can see the fatal cable that cut thru the rocket on it's maiden flight.

The instructions were a little unclear on this cable. As instructed it ended up coming out of the final body tube by about 2 inches, thus placing the cable in the perfect place to cut the tube under extreme deployment. It would be better if the cable were about 3 inches shorter, even though you'd have to reach inside the tube to attach the shock cord, it would present less of a hazard to the rocket. When I reconstructed SkyDream, I did away with the metal cable and just attached the shock cord to the bulkhead directly. The softter cord is not as likely to zipper the tube; when it wears out, I will figure out how to replace it. (in the picture below you can see the fatal metal cable coming out the far end of the rocket, attaching to the hook of a bungee cord that is holding the rocket up. The portion of the cable that comes out of the rocket acts like a knife blade on the tube during ejection ...)

I decided to fiberglass the tube in case I needed to put a big motor in the rocket for a level 2 attempt. The above picture shows the tube after the first layer of glass has been applied. I glassed the bottom 1/3 in 4 oz glass, and the rest in 1.5 oz glass (including the fins). I tried to make it progressively stronger as you move down the body, so I added another layer of very thin (less than 1 oz) glass to the main body tube in attempt to get what I thought was a good strenght-weight distribution. As it turned out, the very thin glass is also very hard to work with, I over thinned the epoxy, and ended up with little bubbles all over the rocket. After much sanding at least I had a nice finish to work with, so I finally was ready to assemble and prime the rocket.

In the future, I'll have to remember to fill the spirals before glassing. You'd think fiberglass would mask the spirals, but they dont!. After I assembled the rocket, I created some mounting brackets for and installed the Adept ALTS2 altimiter, and the rocket was ready to go. Here's a picture of me and my rockets and flight junk the night before we left for SpringFest for it's maiden flight.

SkyDream is Dead! Long live the next rocket.