R&D Corporal Scale Kit Build -- Gary Buck, In Memory Of

I am now in finish work on three HPR builds, some of which have been hanging around for quite a while, a LOC 4-29SS, a ShadowAero/Public Enemy Ultra Fatman, and a Binder Stealth. Given that, I have begun work on two new rockets, one larger, as yet unannounced rocket, and this one which I will be documenting here.

This will be another sport scale build, similar to my LOC Phoenix, but this one has a bit more history. This is a kit from Rocket R&D, and although there are not date stamps on any of the materials, was likely produced circa mid-90's. Rocket R&D was located in Urbana, IL and was owned by Gary Buck. From those that know their rocket history better than I, you may be able to add some detail, but Gary from all accounts was one of the "fathers" of high power rocketry here in the Midwest. Not only did he run Rocket R&D as an early HPR kit builder (as a side job given that his primary job was as an HVAC contractor), but he, while associated with Tripoli Central Illinois #59, ran and promoted the Danville Illinois High Power Launch held late fall each year (see: Danville '98). From this genesis, as I understand it, other companies like Binder and BSD spun off as high power rocket kit suppliers related in some way to Rocket R&D. In addition, the premier Midwest launch today, Midwest Power, was modeled after those early Danville, IL launches after that location was lost and launches thus suspended.

Gary himself was one of the original high power "rocket cowboys" (the torch being carried high by folks like Crazy Jim and Darryl at Wildman Kentucky today). Gary's sense of humor and cavalier attitude led him to step up the power and take chances with his flights and designs. As commented on by the Central Illinois Aerospace website, where Gary was prefect for some time, "It has been said about Gary's rocket flights that they were either spectacular successes or equally spectacular failures, but always spectacular in some manner or other."

I met Gary in early 2007 after moving back to the Midwest from career changes that took me to Texas and California and back again. For those that knew Gary, they might comment, but in my interaction with him, he was amazingly supportive and was always encouraging those around him to strive for new goals in the rocketry hobby. From his inspiration, I decided to set Level 3 certification as a goal and Gary was naturally, my first TAP chosen to review and help with my design. Unfortunately, before even beginning the build of Hope-N-Pray, Gary passed in early 2009. I will always remember Gary's wry smile and sparkling eyes as he told short stories and gave little pep talks at CIA club meetings. Also other memories, like being at Tripoli Central Illinois launches in Tuscola and having him make a banking turn in his ultralight plane around a hanger and buzz the pads while the launch was in progress -- of course, with a big smile on his face! Here are a few snapshots of Gary at some of those later launches.

Rocket R&D marketed a variety of kits, including some from today's manufacturers like PML and Aerotech, but they also had their own line of designs. This included classic 3FNC kits like the Brutus (see attached ad from the February 1994 issue of High Power Rocketry) and a number of scale kits. In fact, one of the tag lines used by Rocket R&D was THE source for scale. I have been able to pick up two of these Rocket R&D scale kits over the years, an ASP and this one.

Nice tribute, mate- I had a Brutus also. It may still be out there-unless the Big Horn Sheep ate it...

Great tribute, Tim! Along with a pair of Brutuses, I still have a R&D 4" Iris and 4" Skyraider waiting to built; love these kits.

Gary Buck was one of the first people I met at my first high power launch a long time ago. Great guy, exciting flights!

Watching with interest....op:

-Eric-

I never met the man, but your story is touching and makes me sad I never will. Thanks for sharing.

Thanks guys.

OK, a little bit more on the Corporal itself. The Corporal MGM-5 was the first surface-to-surface nuclear missile ever put in service by the United States and was originally commissioned by the U.S. Army with Firestone Tire & Rubber and JPL being the prime contractors. The Corporal apparently had a poor service record. The missile required extensive pre-flight prep including loading caustic fuel mixes of red nitric acid and hydrazine. Guidance was also questionable with overall accuracy on test flights in the late-50's of ~50%. Performance was upgraded with the Corporal Type IIB, but it was quickly succeeded by a better performing class of missiles beginning with the MGM-29 Sergeant. (Note: Maybe someone can verify, but there is some evidence in the literature that the Corporal base was transformed/upgraded to the WAC Corporal, but considered a completely separate missile class.)

[video=youtube_share;qZaC1AEMxMw]https://youtu.be/qZaC1AEMxMw[/video]

Saying the above, in the end, the Corporal still makes a cool looking HPR rocket. The Corporal had fairly large plenums that extended outside main body installed in line with the fins (see attached drawings courtesy Peter Alway's Flickr site posting; BTW I would highly recommend Peter's Rockets of the World book series and it's supplements if you can find them). One set, the larger, apparently installed on all versions, was piping for mixing of the liquid fuel. The second, smaller plenum housed Dopler instrumentation and was normally installed in conjunction with a fore telemetry section that extended the length of the missile.

There were/are many color motifs that the missile has been seen in over the years from a solid olive green to a mix of black/white and red roll patterns installed on the fins and body. I have yet to decide what the final color combo will be on this build, but am leaning toward more, not less color.

Before getting into the build, per se, it is probably good to outline the changes I'll be making after reviewing the materials and the scale data. As mentioned this build is sport scale and by no means do I intend to be exactly accurate. But saying that, after looking at the dimensions of the kit, as is, it is somewhat apparent that Gary erred on the side of being conservative on CP/CG ratio and/or designed around materials readily available reducing secondary cuts which add time/money to a kit. In general, I will do some adjustments to more align with the dimensions found in the Peter Alway drawing for the extended/telemetry version as presented in the previous post.

The scale factor for this kit is 13.33% (4" kit dia. / 30" actual dia.), thus the overall length should be 76" (48.5'x13.33%). The length of the kit unmodified is ~86.5". The additional length comes from a combination of factors including a lengthy 34" payload (again seems convenient as you don't have cuts from standard length), an ACE 4:1 ratio nosecone (likely convenience too as this same nosecone is used on other Rocket R&D kits), and larger than scale fins (likely as a safety compensation providing additional margin on the design).

To get the kit closer to scale, the first obvious change is the nosecone. The Corporal nosecone is actually a "coned-ogive" with an aspect ratio of approximately 2.1:1. I'm not going to get a custom cone built for this kit, although I could, and apparently Sandman has done a few of these. Instead, an approximate, but easy option is to drop down to a 3:1 nosecone which I can conveniently swap out from an unbuilt Performance Rocketry Lil' Rascal I have on hand.

Second change is to modify the fins. I played with the overall look/profile a bit and examined the range of motors I expect to use. After several iterations, in the end, to get to a better match to scale, I am going to drop the overall span by 1" and also remove 1" off the aft overhang. This gives me a closer fin profile while still meeting CP/CG requirements.

The final, and easiest change is shortening the payload. I will do so by cutting 5.5" which achieves the total length savings of 10.5" (3.75" nosecone, 1" fins, 5.5" payload). This also makes me feel a bit better about recovery as driving pressure on a full 4"x34" payload isn't always easy. That get's us to the next change, recovery...

The original Rocket R&D kit configuration is single deploy with a bulkhead at the aft end of the payload utilizing a 6" coupler that was meant to be epoxied into the airframe. I prefer to build this rocket dual deploy as I want to fly larger K's and up to an L1400 (although this will be tight) when done. Considering the 6" coupler, it was just too short to reuse as an av-bay, so I took advantage of K&S Rockets recent sale and picked up one of their 4"x8" couplers. BTW, I specifically didn't get/want an av-bay that had an airframe switch band as this would wreck havoc on the strake placement (which I will discuss later).

The other modification to recovery comes in several of the components. As is typical of kits circa mid-90's, this kit utilizes 3/4" wide elastic strap as a shock cord. And the parachute, although nice, is smallish at 44". Also Gary had pre-installed a 1/16" cable as the hard connect to the upper motor mount centering ring. Although this connection point was to be reinforced with a dowel (provided in the kit) and epoxy, I didn't feel comfortable with it. I felt it might still rip through the centering ring, which is fairly thin anyway at 1/8". So, all the components in the last picture attached will be upgraded during the build (including the 3/8" lug which will be changed to a set of rail buttons).

As you peruse the instructions you begin to see Gary's personality come through... Actually on second thought, it doesn't take much peruse'n' as the first line in the instructions says: You CAN'T use too much epoxy... (see below). As you can probably discern, Gary was one to push the envelope.



In any case, the above, although I might not completely agree with said statement, was immediate encouragement for me to do two layers of glass on the fins and CR's. Well, to be honest, there was another reason... Two of the four fins were pretty badly warped and needed some coaxing to get back "in line." This, of course was facilitated by the laminating work and they are now very much in sync with the other two fins.



If you look closely you might see that those four (yes, count 'em, four) fins in my hand are proportionally rather thin for a 4" dia. HPR rocket and you would be right. The fins are only 1/8" in thickness and thus another reason to laminate especially given the aft overhang of 2+ inches for the fins. There is a reason though that Gary went to 1/8" on this kit which will be discussed in a following post...