Tupelo

I had this project in mind prior to the start of my two 2002 projects, the M-Python and the Shock Value. This project combines those two rockets into a two-stage configuration. The objective is to get the highest possible altitude out of my M1315 motor used as a booster. For some reason, I got stuck trying to come up with a name for this project. Whenever I get stuck on something, I've found that the best thing to do is ask the question "What would Elvis do?". If I was Elvis, I would name it "Tupelo", so there you go. One of the most important parts of this project is the transition section which joins the two rockets. Eric Haberman from Dynacom and I spent a long time designing this, and Eric's close-to-final drawing is shown below:

Shown in the "dumb rocket photo" at left is the last photo taken prior to launch on June 19, 2004. With my slow work pace, it took me 2 and a half years to get to this point.

The sustainer is friction fit into the transition, and the staging electronics will be in the booster. This is generally considered a risky thing to do, as drag separation must be avoided, but there was simply no room in the sustainer to do otherwise, and adding conduit down the side of the sustainer and cutting into the transition was "beyond my scope" at least for this year.

Shown below is the final transition section from Eric. It is a great piece of work. It's a little difficult to see, but the aluminum sleeve sticking out has the same taper as the fiberglass. This entire section of fiberglass is of monolithic construction wound on a single mandrel. The coupling shoulder on the left hand side is machined in.

Below is a view from the top looking into the transition section. You can see the straight cylindrical ID of the aluminum sleeve. I've been having nightmares for months about a "fold" failure at the transition, but finally having this piece in my hands has been very reassuring. There are plenty of things still to go wrong, but I don't think that the transition section will be a problem.

Below is a photo of both stages fit together in an attempt to convince myself that the transition section can support the sustainer.

I have hopes for this project to reach an altitude greater than 40,000 feet, and that is the point at which all commercially available altimeters peg out. Originally, I thought that I could integrate the accelerometer data as a substitute, but the more I learn, the more I realize that approach will not work. My only hope of legitimately recording the altitude is to use GPS. Bummer, because the second stage is all carbon fiber, which is conductive, and will not allow signal from the GPS satellites to reach the rocket. I have had to stop everything and build a payload bay from non-conductive fiberglass.

In order to match the outside diameter of the rest of the second stage, I conducted a search for commercially available or re-workable fiberglass tubing...no dice. I need to make this airframe section myself.

Having some knowledge about what is necessary already, I've picked out a technique, and have decided to laminate a lame cardboard tube with glass using porous shrink wrap tape to squeeze out the excess epoxy. To do this I needed to build a curing oven.

Here is the result of my first tube laminating session, a humble looking cardboard tube wrapped with two layers of 3 oz. fiberglass, the first of which is bias cut (45 degree angle). To the left is the coupler cut from a spent Aerotech K250 single use motor. What's left of the spent motor makes a nice black fiberglass coupler tube. Doesn't look like much but it is strong and light.

I purchased an RDAS GPS expansion board and antenna from Dewayne Doud, and he was kind enough to deliver it to my house when he was in my neighborhood. This is an early version board and it uses quite a bit of current. I soon realized that ordinary 9V batteries would not be suitable and on the advice of the RDAS Topica discussion board, I decided to incorporate a rechargable 9.6V NiMH battery pack. I built it into the payload bay's coupler and potted it with two-part foam and epoxy. It was difficult to fit all this stuff into a 54mm airframe, and I had to get help from Duncan McDonald to change the connector on the antenna from straight to right-angle.

To summarize, the sustainer has an RDAS compakt with the GPS expansion board and is powered by a rechargable battery pack located in the coupler underneath. I built in recharging banana jacks in the base of the coupler so that I could easily charge it in the field just prior to flight.

The booster's electronics were located in the interstage coupler and consisted of two separate items. First, a tried and true Blacksky Altacc to deploy the booster's main parachute at apogee. I decided not to mess around with dual deployment for the booster. Second is an Adept ES231MH staging device to ignite the sustainer motor. This is a funky device that uses a spring loaded lever as a g-switch...very Soviet-era! It was the only thing I can find that had a small form factor and had a programable coast time between stages. The Adept stager uses an outboard rechargeable 9V NiCad battery to supply high current for the igniter. Here's a photo of everything in their relative positions. Please note they are missing their switches and batteries for the most part. Not shown is the Walston transmitter that was sewn into the streamer with kevlar thread just like the original test flight.

I decided that I could get ready in time for the MudRock launch scheduled for June 19, 2004. Instead of the cool but scary 1990 VW camper-mobile, I thought a regular RV would be a better choice, so I got a generic P.O.S. fiberglass unit of approximately 25 feet. It worked out fine. My Sr. Director of Field Operations was my brother-in-law Jeff, a geologist and physics teacher who pointed out all kinds of "basin and range" geological fine points to me on the drive up to Black Rock. You can see him below Friday evening helping to do some last minute trouble-shooting with the digital volt meter.

Sunset Friday night prior to the big show!

Saturday morning at the ergonomic work station.

At the pad with Tom Rouse, his son, and Jeff.

Recovery was exciting...everybody but me could see the booster deploy its parachute and track it down to the ground. I was focused on pointing my walston receiver antenna at the sustainer so that I could make sure that apogee deployment went off as planned. Sure enough, I acquired the signal at the planned apogee time of t+60 seconds. To make a long story short, I lost the signal after about 4 minutes, and ended up visually tracking somebody else's rocket. Fortunately, Chet Geyer volunteered to help pick everything up. He took his Jeep out to the booster while Tom Rouse and I tore off in Tom's truck to pick up the wrong rocket. After determining that I had screwed up, Tom and I looked over in Chet's direction and got a headlight flash from him. We drove to Chet's Jeep and picked up the booster. I did another Walston check and still couldn't get a bearing, but Chet advised that the sustainer should be on the same bearing from the launch site as the booster, and we all picked up and drove that way...Chet on the line and Tom and I parallel to the right. 1.8 miles along we saw Chet stop and flash his headlights again. He had found it! I must say that Chet Geyer is spooky-good at finding these things, and I consider myself very lucky to have had him volunteer for search duty. Thank you Chet.

That's about it. I'm going to retire this rocket (it's too much work!). This flight got the TRA "M" class altitude record, so I'm happy about that. A summary of useful information I learned from this project is:

1. I used a Rouse-Tech CD-3 CO2 deployment device for sustainer apogee. It worked well with a 16 gram cartridge. This is relatively new technology so I hope this serves as a confidence builder.

2. If I ever do another two-stage project, I will certainly use drag separation for staging, rather than the method I used for this one. Drag separation will give better performance and a much easier clean-up chore!

I usually work in the "lone wolf" mode, but this project was complicated enough that I needed plenty of help. I would like to acknowledge and thank the following people for their help:

Tom Rouse for the K250, machining job on the nose shoulder, the CD-3, getting the grains unstuck from the M liner, the booster chute, the paint, the nice camping spot near the celebrity section of the flight line, crewing at the pad, and helping me recover from a mental "blue screen of death" shortly before the flight.

Dewayne Doud for delivering the gps and subsequent tech support, and post flight data alnalysis with his thinkpad.

Duncan McDonald for the SMA fitting on the GPS antenna.

Peter Clay for lending me a back up Altacc.

Erik Ebert for the sustainer igniter.

Gabriel Bilek, Stan Hemphill, and Lee Treichera for helping me figure out how to charge the NiMH battery pack.

Sue McMurray for pointers on the interstage design.

Bob Fortune for help with selecting the altimeter.

Chet Geyer for finding it! His experience, skill, and intuition are second to none.

Mike Brest for his excellent advice on the streamer.

Geoff Huber and Bill Schwrorer for their help with RDAS data analysis.

Gary Rosenfield for help with the motor assembly on-site.

Brother-in-law Jeff Freeman for his general crewmanship on-site and on the road.