LDRS XVI or
How I Spent My Summer Vacation

by Chuck and John McConaghy, Lunar #359 & #360

(46KB)
Photo 1. View of the LDRS XVI flightline.

Its probably been two years since we really got serious about this high power rocketry stuff. A lot of that had to do with attending LDRS XIV at the Black Rock Desert in the summer of 1995 and watching those giant rockets take to the sky. By the way it wasn't until a year later that we discovered what the acronym LDRS meant. (It means Large and Dangerous Rocket Ships.) Every year LDRS moves to a new location around the country and this year's event was held at Hartsel, Colorado. This particular location had been the site of some of the earlier LDRS events in the 1980's. It was also billed as an extreme altitude launch since elevation is 8800 feet. (One advertisement said that all rockets were guaranteed a minimum altitude of 8800 feet.)

When we looked at the map and found Hartsel, which is just a small dot and isn't much bigger when you get there, it didn't seem all that far from California. We decided to drive since going by air with a bunch of large rockets (not to mention the camping equipment) seemed difficult. LDRS was a four day event that started on Thursday August 7th and ended on Sunday August 10th. We arrived on Thursday at Hartsel and didn't see any signs of a launch but asked for directions to the camping location and when we turned on to the side road we saw a little white sign that had the letters LDRS. When the side road turned to a dirt road, I knew we were getting close. The launch site was a very large open range. In fact buffalo are raised at this site and a large herd could be seen off in the distance. The people taking the parking fee at the gate told us to follow the dirt path across the range and to slow down when we crossed the old irrigation ditches. They said they made very good speed bumps for those that tried to drive too fast.

(58KB)
Photo 2. The mosquitoes were hugh in Colorado this summer.

This particular launch site, as mentioned, is a very large open plain with no trees and many rocks intermingled in the very short grass. Far off to the distance in the west were many snow covered peaks of the Rockies. Immediately off to the east of the launch site was a small hill which, because of the prevailing wind from the west, became the landing spot for many of the rockets. Some of the higher altitude launches ended up on the other side of the hill making recovery a little more difficult since they were out of view. The parking area had vendors representative of all aspects of high power rocketry. These vendors included Kosdon, PML, Magnum, Binder Design, Rocketman Enterprises, Rocketdyne, Advanced Propulsion Systems, Aerotech, Dr. Rocket, Robbyís Rockets and many others. People came from all over to attend this event. We met people from Illinois, Alabama and a very large group from Texas. In fact, there was one large rocket from Sweden. We even recognized a few people from California including Scott Bartel of Delta V Rocketry.

(64KB)
Photo 3. John recovers the successful Level II certification flight of our PML Ariel.

One of our personal goals for this launch was to have a successful Level II certification flight. By Tripoli rules, Level II requires a J engine or greater. We had previously bought the very popular J 350 engine. It is popular because it uses 38mm hardware and the reload kits are ìeasy access.î However, we also learned an important lesson. That is because of its popularity, nobody had reload kits for this engine or had sold out prior to our arrival early on Thursday. The lesson is to reserve your reload kit in advance. Luckily, we had one reload kit with us so we would have one shot at Level II. In preparation we had also bought an ALTS25 altimeter by Adept electronics and had originally planned to do altimeter deployment of the chute. This particular altimeter is set up for dual deployment. However none of our rockets have the dual deployment feature but we had modified them all for single stage deployment. However, in the end we decided on using the standard delay that comes with the reload kit and let the altimeter just ride along and record the altitude. We had also planned on using the J350 engine in our 4"; diameter Excel Plus. On Friday we launched the Excel Plus (to check out the altimeter) with an I357 engine and recorded the altitude at 2350 feet. However, even though the Excel Plus which is made out of cardboard tubing can supposedly handle a J engine (we even confirmed it with Tom Binder who was at the launch), we felt safer putting this engine in our PML Ariel which is constructed of phenolic tubing with fiberglass fins. The Ariel is 3"; in diameter and preflight computer calculations indicated that with a 14 second delay it would go to 5000 feet on the J350. Saturday morning had the clearest skies and best weather for the entire event. So we set up the Ariel with the J350 and used one of Robbyís Rocket large diameter igniters. We had a Tripoli Official watch while we held our breath and the camera. (One advantage of LDRS is there is no shortage of Tripoli officials.) Liftoff was fast and it appeared that there was some material blowing in the air where the rocket had just been. We thought it was a shred but when we looked up and saw the rocket still going and going. (Later it was speculated that some material was blown off the ground or pad by the engine exhaust.) It was a great relief to see the parachute come out and then begin visually tracking its descent back down. Of course it went directly into the sun and we lost it. Upon heading toward the hill where we thought it would land, we caught site of the red and white parachute while it was still up about 1000 feet and knew that must be our Ariel. We were able to see it land and John ran up the hill to find it in good shape and beeping out the altitude of 6750 feet. The original predictions, which even took into account the 8800 foot elevation, assumed a CD of 0.6 but a postflight analysis with a CD of 0.4 gave a more accurate agreement with the measured altitude.

(10KB)
Figure 1. Altitude predictions compared to measurement.

As far as the rest of the event went, the weather was probably the key factor. It only actually rained once, shutting the launch down early on Saturday afternoon. However, many other times it was cloudy where rockets with altitudes greater than 2000 feet would be swallowed by the clouds and sometimes reappear with parachutes deployed. There were many windows of clear sky or holes in the clouds which people took advantage of. The FAA waiver was for 10,000 feet with windows to 18,000 feet. The waiver ended every day at 4:30 p.m. which sometimes caught us by surprise. On the first day we were trying to launch our brand new LOC MiniMagg on an H242 when the igniter failed. (I was trying a brand I donít normally use.) In any case we ran out of time and had to launch the next morning. We bought a bag of Robbyís rocket igniters and even got to talk first hand with the man that makes them and he guaranteed no failures and instant ignition because they burn symmetrically and hot. (We had very good luck with these igniters.) Other things we noticed included Advanced Propulsion making a large pitch for their new engines. They had a professional booth with a video presentation. For those that havenít seen these engines, theyíre pyrotechnically spectacular with the Spitfire literally spitting out bits of fire as the rocket goes skyward while the Red Eye engine puts out a brilliant red glow. There was one large cluster rocket that had 4 Redeye engines with an even larger center mounted engine that was supposed to air start. The red eyes performed well but the main engine never went. It isnít clear if we will ever see any of these APS engines in California. At the moment APS doesnít have a DOT approval not too mention a CFM approval. Also at LDRS were some large M engines that had a beautiful green flame. I think these engines were made by Kosdon. There was one launch on a Kosdon N engine that literally shook the ground where we were standing. LDRS had several altitude contests including closest to 5000 ft and closest to 10000 feet. There was also a contest for landing closest to the launch pad. On Saturday PML sponsored a fund raiser dunk tank and had all the various vendors take turns. John spent a lot of time and dollars throwing balls and dunking the participants. Even though it was a little further trip than to a Lunar launch at Robertson Park, we had a great time.

Information date: September 14, 1997 lk