Welcome to the Rocketry Planet How-To Classroom Series!

It's that time of year again: Labor Day is behind us, the kids are back in school, and that means it's time for us adult kids to get back into the How-To Classroom! This edition of the How-To Classroom is based on the Estes Maxi Brute Honest John, a 1/9 scale model of the venerable M31 Honest John ballistic missile used by the United States Army. This class covers the Estes first edition Maxi Brute kit #1269 released in 1975, the Estes second edition Collector Series kit #1269 released in 1993 or the third edition Maxi Brute kit #2166 released in 2000.

This kit is approaching collector status, if it hasn't already, and you can still find them occassionally on eBay for reasonable prices. In this class series, we will be building three at one time: two 38mm versions and one 54mm version. All three will feature dual deployment with altimeter bay, fiberglass airframe reinforcing and fiberglass fins to replace the thin styrene shells that come in the standard kit. In fact, of the original kits, we are mainly using the styrene fin canisters and the two-piece styrene nose cones while replacing most everything else — this is imperative to be able to fly these kits on 38mm and 54mm motors.

The Maxi Brute Honest John came in several flavors, but all the parts were much alike. This is a Collector's Series, which came with a certificate of authenticity.

Before the purists and collectors shudder, all of the kits I am using in this class were opened and assembly contemplated before I purchased them, meaning the fin canister and nose cone base had been cut apart, but no actual assembly had taken place. So they were opened kits — my unopened kits are still safe and sound.

The original model was designed to fly on 24mm motors, and many have been built and flown successfully — plus they just look cool when painted olive drab. The Honest John is a classic rocket enjoyed by many, featuring a two-piece blow-molded styrene nose cone which had simulated spin thrusters on the lower nose cone base. The fins were molded styrene shells, which were meant to be glued together and then glued to the blow-molded styrene fin canister. Anyone who has every built one knows these were notorious for coming off, either in flight or upon landing. And the nose cone shoulder, being only 1/2" long was always a problem waiting to manifest itself.

Based on a BT-80 airframe tube 14.25" long, when combined with the fin canister and long oversized nose cone, the Honest John model stood 37" tall when assembled. In this class, we will be replacing the BT-80 with 2.56" LOC/Precision airframe tubing, which is a perfect replacement, while using 2.15" (54mm) LOC/Precision airframe tubing for the altimeter compartment and main parachute recovery tube. The BT-80 with fiberglass reinforcement could be used if you wanted to, but I chose to upgrade it. At the same time, LOC/Precision 2.56" coupler tubing will be used to extend the nose cone's shoulder another 2.5", to give a much sturdier base in flight. It's all a tight fit, but you are going to be surprised at how well it works out.

Testor 3501 Plastic Cement

We will be using a number of different adhesives during this build since we are going to be dealing with various components: styrene, cardboard, plywood, fiberglass cloth, G-10, etc. There are some considerations to be made about how to best adhere the styrene plastic to the cardboard and to itself. Plus, there are normal places where basic hardening is better achieved with the right adhesive as well.

Typically, model building with styrene has been done with plastic cement. Testors is a popular brand of plastic cement and has been around for decades, considered a mainstay in plastic model building. The gel-style tube-delivered thick cement melts into the surrounding styrene and when it dries, if forms a good bond. Testors No. 3501 (pictured at left) is typically the type of plastic cement you will find in your local hobby shop but any similar brand designed for use in styrene plastic model building is suitable.

A disadvantage of using this type of cement on styrene plastic is that it can soften and melt the surrounding styrene parts, often distorting thinner pieces. It is beneficial for general plastic model building and will be used on this project in areas where a thicker bonding joint is available so that melting isn't a consideration and where there will be styrene-to-wood and styrene-to-cardboard joints, as the plastic cement is capable of penetrating into porous materials and developing a good joint.

Tenax 7R Plastic Welder

For styrene-to-styrene joints, such as where the spin thrusters shells mount on the nose cone, a different adhesive will be used. In this case, the product is Tenax 7R Plastic Welder by Hebco of Hohenwald, Tennessee. Tenax 7R Plastic Welder is a very thin, solvent-type plastic model cement that actually welds parts together. Very fast drying and very strong once dried, it has been said that when you put it together with Tenax 7R, it isn't coming apart. Tenax was used in the D-Region Tomahawk build with good results, so we can expect the same here.

What you have to remember is that you aren't cementing or gluing with Tenax, you are welding. Actually, you are dissolving the plastic, which, when the solvent evaporates, the plastic reformulates together into a very strong bond. You use it by holding the parts together and then flowing small amounts into the joint. Capillary action draws the thin liquid into the joint, melting the plastic together and forming the bond.

Insta-Cure CA

The two most common types of adhesive we will use in our construction are basic hobby staples: two-part hobby epoxy in the 12-15 minute variety and thin cyanoacrylate (CA) glue. I patronize local hobby shops for these products, and usually end up with the Bob Smith products. For this particular classroom project, I am using 15 minute Bob Smith brand two-part epoxy and Insta-Cure CA in the 2 ounce bottle. As with any epoxy and cyanoacrylate, proper storage of these product will lengthen their shelf life. Cyanoacrylate can be stored in the freezer section of your refrigerator for a long time. When you aren't using your epoxy or cyanoacrylate, replace the caps and store them airtight.

Finally, for the purposes of airframe lamination with fiberglass cloth and the construction of the custom fiberglass fin shells, I called on West Systems two part lamination epoxy. This product is used in the marine world and is known everywhere for its quality and strength. I ordered a 1 gallon kit, using the 105 resin and the 205 hardener, from my friends at Mr. Fiberglass, and have the benefit of knowing it will take me a long time to use that much. I am adamant about fiberglass reinforcing my rockets because I really tire of the ding and dent maintenance I used to get from flying unreinforced rockets. And, I wouldn't think of getting the epoxy without getting the pump kit — for $11, it's well worth it to take away the guess work of mixing.

Gougeon Brothers, Inc.'s West Systems epoxy is some of the best epoxy you can get for laminating airframes with fiberglass cloth.

Speaking of airframe lamination, most people who have never tried this may balk thinking it is too difficult or they lack the expertise to be able to successfully do this. It is easier than you think, and as anyone who has used the right components know, it's not really that hard to do once you get the hang of it. You just need to get the right components to do it with. For me, that means tubular fiberglass sleeving. Today, your best bet is Soller Composites, who has a very expansive website with just about anything you could want. For this project, I selected their 3" light weight fiberglass sleeve, and planned on doing just a single layer. This is enough to add substantial strength to our project.

I've already discussed a few of the replacement parts the class will use, such as the 2.56" airframe tubing, 2.56" coupler tubes and 2.15" (54mm) airframe tubing from LOC/Precision. In addition, we will need a 2.15" (54mm) coupler tubes, 1.5" (38mm) motor mount tubes, a number of centering rings and bulkhead plates, including:

• 2 centering rings to fit a 38mm tube inside a 2.56" coupler,
• 6 centering rings to fit a 54mm tube inside a 2.56" coupler,
• 4 centering rings to fit a 38mm tube inside a 2.56" airframe tube,
• 2 centering rings to fit a 54mm tube inside a 2.56" airframe tube,
• 9 bulkhead plates to fit a 54mm tube, and
• 3 bulkhead plates to fit a 2.56" tube

General Tools No. 55 Circle Cutter.

Don't be overwhelmed — remember I am building three at one time. I cut most of my rings and bulkhead plates myself, using 1/4" and 3/16" birch plywood from my local craft store, although some of the centering rings used in the project are extremely thin, like the ones that place a 54mm tube inside a 2.56" coupler, so it might be a good idea to farm that. I had the really small ones made by Patrick Waite of CNC Rings N Fins (http://www.cnc-rings-fins.com/), and the results are perfection.  For the ones I cut, I used an adjustable fly cutter. I purchased the General Tools adjustable circle cutter (General No. 55) online for my hobby use. It features a 1/2" chuck, 1/4" pilot hole size and cuts holes from 1-3/4" to 7-7/8" in diameter. By flipping the cutter bit, you can make inside and outside cuts.

In addition to all this, sheets of .062" G-10 will form the core of our fins, and the two 38mm birds will use the Giant Leap Rocketry Groove-Lok to positively position the fins at the right angles while the 54mm bird will have the fins mounted directly to the motor mount tube. AeroPack will provide the two 38mm and the single 54mm motor retention hardware, while the rest of the miscellaneous hardware will be shopped at the local hardware store, such as the eye bolts, all-thread, nuts, washers, etc.

Some might say, "How can you get a dual deployment arrangement into such a small kit?" It's really simple with this kit, because Estes did us the favor of making the nose cone in two pieces. With the main chute stowed in the forward nose cone section, and the altimeter in the rear nose cone section, leaving the airframe tubing to carry the drogue, we have plenty of room to make this work.

I built this same kit in 1995 with a 38mm motor mount and a dual-deployment arrangement, so this is where I draw my experience for this class. The illustration above displays the concept of the dual-deployment layout, with the altimeter vent holes drawing air through the spin thrusters and into vent holes in the forward end of the altimeter bay. I flew my 1995 version many times to altitudes regularly over 4,000 feet, deploying a large streamer at apogee and a 30" parachute for the main using an Adept ALTS-2 altimeter.