Background

The Sizzler (#2127) offered by Estes, is a rocket with sharp looks and special features. The Sizzler is advertised by Estes has being 70 centimeters long, 4 centimeters in diameter, and 110 grams when finished. Recommended motors are the B4-2. B6-2, C5-3, C6-3 and C6-5. This bird is on the larger side for B and C power, so I was planning to investigate using 18 millimeter AeroTech D reloads or possibly the 18 millimeters D motors offered by Apogee. More on this later. 

The real reason I built this rocket was to investigate the unique rear deployed parachute system that it uses. The nose cone is permanently glued to the body tube and the motor is mounted in a long motor mount tube that is blown out the rear of the rocket when the ejection charge goes off. A 46 centimeter parachute is attached to this motor mount and the mount itself is attached to the rest of the rocket with a standard elastic shock cord. Of course, the rocket descends nose first instead of tail first, but that should be easier on the balsa fins when meeting the ground after a flight. 

Construction

The basic design is what I call "a rocket in a rocket". A smaller body tube carries the motor mount tube inside the outer body tube. It is located by large but standard looking adapter rings. This inside body tube extends nearly to the nose cone and is capped at that end. The outer body tube is slotted for "through the wall" fin attachment, a nice feature. The fins go through these slots and butt against the inner body tube, which makes them very strong. Estes is using "through the wall" fin mounting on several of their rockets. This feature makes accurate alignment of the fins quick and easy. 

Constructions is along pretty normal lines using typical glues and finishing materials. I used Titebond aliphatic resin glue for all construction and Krylon white finishing primer and enamels for painting. The kit parts were of high quality, typical of an Estes product. The die cutting on the fins was clean and accurate. Tubes and rings had no flaws. The nose cone was a little rough with molding flash but cleaned right up with an Xacto knife and sandpaper. The only flaw was that the slots in the outer body tube were to narrow for the 1.5 millimeter balsa fins. I solved this problem by using a sanding block to carefully sand down the thickness on the fin tabs that extended through the tube until the fit was "just right". I simply rounded the fin edges instead of streamlining them. the balsa grain was filled with Pactra Prep, a surface filler that I like. It dries quickly, sands easily and two coats are all I typically need for good results. 

I just followed the instructions and the rocket assembly was a breeze. The only modification that I made was to file a small notch in the rear motor mount ring so that the shock cord was not pinched when the motor mount was in place. I spent some time making sure that the fit of the motor mount rings and the inner tube was just right. A little light sanding on the rings with 400 grit sandpaper made the mount slide smoothing and easily, but still stay in place with a motor loaded. 

A coat of Krylon white finishing primer was sprayed on and sanded smooth with 400 grit sandpaper after it dried. White Krylon was next, then masking and yellow Krylon on the front 1/3 of the rocket. I applied the kit decals and then used Krylon crystal clear as a top coat. Looks pretty good! 

Flight

The first flight was on May 3, 1998 at a C.R.A.S.H. launch in Denver. Warm, sunny, light breeze - a perfect flying day. The rocket was prepped per the instructions that Estes provided in the instruction sheet. This flight was on a C5-3. Boost was straight and surprisingly high for a rocket of this size and weight. Recovery deployment appeared normal and the Sizzler descended normally on its 46 centimeter parachute. Upon recovery I discovered that the parachute's shroud lines had tangled with the shock cord on deployment, but I still got a fully opened parachute, lucky! Post flight inspection showed everything to be OK except that the elastic shock cord was scorched where it attaches to the back of the rocket. I am going to change the shock cord attachment by drilling a small hole at the base of one fin and attaching a length o 100# rated Kevlar® shock cord and then tying the present elastic shock cord to that so that I is all inside the rocket when packed. This will keep the elastic from being exposed to the hot exhaust gases. As it is, the shock cord attachment would probably fail in a few flights, not good. If I build another Sizzler, I will do it this way from the start. 

The prepping instructions by Estes did not give me a clean recovery. I am going to experiment with other packing arrangements. I think the problem is that the shock cord is wound over the top of the parachute. I believe it would be much better to pack the parachute on top of the shock cord. Well, this is the reason that I built this rocket in the first place, to learn about the problems with rear ejection. 

As I mentioned earlier, this rocket can easily handle more power. It would be a very stable platform for AeroTech or Apogee 18 millimeter composite motors of D power. Its construction is very strong and its flight manners are sweet. I will certainly be trying these in the near future. 

Grades

Design: B 
Construction: A 
Flight: A 

This is a really cool looking rocket with a very stable and satisfying performance that is flawed only by a few details in its recovery system design and instructions. While not for the beginner, I would recommend this rocket to any rocketeer looking to find out about rear recovery ejection.