Getting rocket altitudes was tough in the old days...

Ed Mitton left a very interesting comment on my last post about tracking rockets with theodolites... In addition to trying to see a pretty small rocket at apogee, he reminded me of the need for proper equipment:

"A little history on tracking at NARAM 11...The Peak City Section of Colorado Springs owned a pair of tracking theodolites that featured a 90 degree bend in the optics near the eyepiece and some pretty hefty magnification. This combination made them extremely difficult to follow and mark rocket flights. On the first day of NARAM 11 only a small handful of egglofter flights enjoyed a closed track. Thankfully, one of the East Coast sections in attendance had brought along a set of straight line tracking devices which were pressed into service for the remainder of the contest.

Fast forward a few years - the Peak City theodolites were part of the range equipment donated to ROMAR in 1973, so I had first-hand experience with trying to use them. No wonder there were problems at NARAM! I practiced with one of the scopes for probably a dozen club sport flights, and not one of them could be kept in the field of view. A major fail! "

So not only did trackers have to have keen eyes, they also had to have equipment that allowed them to easily fix on the rocket. I can see where sighting down into an eyepiece rather than looking at the rocket would be kinda iffy. I never experienced the issue Ed had, because I shied away from altitude events - which were hard - in favor of the easier duration contests. No unclosed tracks, and building skill was not a major factor, as it had more to do with the biggest parachute or streamer you could pack into a given diameter body tube.

In my brief contest rocketry sortie, I heard complaint after complaint about tracking. Altimeters are much easier to use, even if they do add a little weight (very little - the Adrel altimeter flown in many contests weighs a scant 1.2 grams without the battery, which adds another 2 grams). Despite this, there was a bit of a debate among the contest rocketeers about using altimeters during the late 1990's and 2000's - a confidence/trust issue, I think. Things settled down in the past decade, and the advent of the NRC pretty much drove the stake into theodolites. To quote a contest rocketeer (Don C.): 

"Small clubs and lack of volunteer staffing had all but eliminated altitude events anywhere but NARAM. Even at NARAM, the job of doing tracking fell to the same unfortunate few who had experience with it. Theodolite tracking is dead, mourn it if you like."

As a final note, Chad Ring produced a short R&D report comparing altimeter readings versus theodolite altitudes for 20 flights of an Estes HiJax on C motors. I have graphed the results below - you will note that the altimeter and the theodolite readings are very similar, and the second plot shows an apparent random scatter around the 1:1 line, meaning there are no real systematic differences. Also, Chad had unclosed tracks for 3 of the 20 flights, whereas the altimeter failed on one. Altimeters are the way to go!

Graphs of the data presented in Chad Ring's R&D report (Click to enlarge).

I really wish I can attend a NARAM soon - I bet tales of the "old days of tracking" are very much like my dad's stories of fighting bears to get to school, which was uphill both ways.

An awesome present!

Today's mail consisted of the usual junk ads and bills, with one exception - a large envelope with Ed Mitton's return address in Colorado. Ed has been in rocketry as long as I, and he was a NAR contest rocketeer while I was still futzing around in the Estes Aerospace Club. I keep track of his very nice rocket blog, Blast from the Past, enjoying the build threads and flight reports. Needless to say, I was very curious about the contents of this envelope and wasted no time opening it. Here's what I found inside:

Letter and NARAM 11 flight card (Click to enlarge).

A flight card from NARAM-11? Holy cats! I could not think of a better present for an old rocketeer like me, with a passion for the history of our hobby. If you look at the flight card, you see that it was designed to allow for the recording of information pertaining to all events flown at that NARAM, including scale. You will also notice that there are sections for recording the tracking information for the altitude flights - azimuths and elevations given by rocketeers manning trackers similar to theodolites. Using some trig formulas and tables of sines and cosines, the altitudes were computed (see here for the old Estes technical report on altitude tracking); if they agreed to within a certain percentage (10% in this case), "the track closed" and the flight's score was valid. A "track not closed" meant no score and a reflight - a real bummer to most rocketeers.  Many rocketeers put colored powdered chalk or equivalent in their models so that the trackers could fix on the bright colored cloud produced at ejection.  It helped, but the model got covered in the powdered chalk - kinda messy, to say the least. So you can understand why there were many pre-contest prayers for the trackers to have keen eyesight and be familiar with the equipment. 

Charles Russell and Bill Roe (right) at NARAM-11, which was held at the U.S.
Air Force Academy in Colorado (Click to enlarge).

This flight card is a very cool glimpse into 1969 contest rocketry, about a year after I started in the hobby. After scanning the card and letter, I placed them back in the plastic bag and put it in my stash of rocket memorabilia. Thanks very much, Ed - your gift made my Tuesday!

Camera Carrier...

I managed to get my Astrocam into the air back on September 27; on this, its only flight so far, the flimsy body tube suffered some damage. As I mentioned back in this post, I was worried that the rocket would not last long, and had started designing a new Astrocam carrier rocket using a normal strength BT-50 tube and the Generic fin can. However, the design, which you can see below, never really caught my fancy - guess I have built too many of the E2X Generic series of late. 

My initial Astrocam carrier design (Click to enlarge).

Yesterday, I was searching through an old parts box (the rain outside precluding any other rocket activity) and came across my old Estes Camroc. Then I remembered that the first carrier rocket for the Camroc was the nice-looking 2 stage Astron Delta, and that it was also BT-50-based. That's when the notion struck me - I could build a Delta, and have it loft both my Camroc (now non-functional) and the Astrocam. Forget designing my own - it was time to go old school!

The Astron Delta in the 1972 Estes catalog (Click to enlarge).

The first thing to do when building an old design from scratch is to grab the instructions and review the parts list. This I did, and I realized I had all the parts, including some spiffy laser cuts fins from Semroc, which would make life much easier. I had started pulling the pieces from my bins when I noticed something funky about the JT-50C couplers. Of the 6 I had, 3 were 1" in length and the others were 1.5" long. But the labels on all six said 1.5", contributing to my "WTH" moment. The 3 short couplers were from the older Carl Semroc days, and the long new ones were bought after eRockets took over, which was suspicious, so I glanced at the Delta instructions. It had drawings supporting the 1" length of the JT-50C. I then got online and consulted the 1974 Estes Custom Parts Catalog (a sacred tome to us cloners) and it gave the length of the coupler as 1". Be warned, fellow scratch builders - the eRockets JT-50C is 0.5" too long - probably not an issue in most builds, but ya never know. My guess is that Randy took the the typo on Carl's label seriously and made all his JT-50C couplers 1.5" inches in length. But the original JT-50C was definitely 1" in length.

The other "WTH" moment came when I tried locating the launch lugs called out in the Delta instructions - 2 LL-1B's. I couldn't find any in my large launch lug stash, so I consulted the parts catalog to get the lengths, figuring I would cut two larger lugs to the right size. Guess what? There was no entry for LL-1B, or LL-1 anything in the catalog - only LL-2A, LL-2B, LL-2C and LL-2D. Scratching my hairless head, I did some more googling and discovered that Estes had changed the part numbers sometime around 1970, with the LL-1B becoming the LL-2B. Those I had, so all good.

I have gathered all the Delta parts into a "kit", ready to start the assembly process. Which isn't going to happen for a while - I have 5 projects needing to be completed, and I promised myself no new builds until they are done. But I really, really want to build the Delta, so I'm hoping to channel this desire into action on the build backlog. Maybe I will be able to start on my camera carrier in December.

My Delta "kit" (Click to enlarge).

My vintage Camroc (Click to enlarge).

We shall see...

Halloween launch!

Rockets awaiting their turn to fly (Click to enlarge).

This past Sunday (October 18) several of us gathered in Research Park to fly a few rockets. In addition to myself, there was Duane (who flew nothing, but helped out with his customary cheer), Allen, Vince, Brian, Martijn and family, Art, James and grandson, Chris, and Greg - pretty good crowd for a Sunday afternoon launch. Vince had led me to think that he was going to be flying some Halloween-themed rockets (turns out he brought only one such critter), so I dug out several of my creepy birds to add to the spirit of the occasion. Even though it was less of a Halloween launch than I expected, a lot of model rockets took to the air, and a great time was had by all on the field. In this post, I'm going to focus on what I flew, and maybe hit some highlights of the afternoon towards the end - there's always some excitement, ya know.

My Generic clears the rod (Click to enlarge).

Me hooking up Ecto-1 (Click to enlarge).

The first rocket I launched was the only non-creepy one - an Estes Generic on an A8-3. Flight was straight up with a good parachute deployment, but for some reason the FlightSketch altimeter tucked inside the bird recorded screwy (i.e., unbelievable) readings. Maybe it was because the altimeter was loose inside the model or maybe it got stunned when Brian caught the rocket just before hitting the ground - I don't know. It'll be interesting to see how the altimeter behaves when I fly it again.

Ecto-1 gets going (Click to enlarge).

Witch Hazel makes her annual flight
(Click to enlarge).

The next rocket of mine to fly was Ecto-1 - a Der Red Max with Stickershock Ghostbusters decals. It got some pretty decent altitude on a B6-4, and made a nice slow descent under an Apogee 15" nylon chute. Ecto-1 was followed by my venerable clone of the Estes Zoom Broom. Old Witch Hazel would curse me if I didn't fly her in October, which she did this year on an Estes A3-4T. Not the recommended motor, but I seem to be out of A10-3Ts - don't know how that happened. At any rate, Hazel had a good ride.

Brian launches my Spooktacular
(Click to enlarge).

The Spooktacular under chute
(Click to enlarge).

Flight #4 was that of the Excelsior Goony Ghost, powered by an A8-3. The kiddos always like the Ghost, and its flight was picture perfect, landing a short distance from the pad. The OOP Quasar One Spooktacular was next, doing well on a B6-4. It is also one of those once-a-year-in-October birds - Quasar One went belly up about ten years ago, and the Spooktacular is beginning to show heat damage in the main body tube at the end of the motor mount. I very much like its look, so I am trying to lengthen its life as much as possible.

The Goony Ghost starts moving
(Click to enlarge).

The A8-3 in my Zombie ignites
(Click to enlarge).

The sixth rocket to leave the pad was the Estes Zombie - this ARTF (Almost Ready To Fly) model made its maiden voyage propelled by an A8-3. Good chute deployment and a gentle touch down on the grass. Then it was my Goblin's turn to fly. I may be old, but I ain't stupid, and there was absolutely no way I was going to put a D12 in that lightweight rocket given the wind and our small field. So I adapted down to a B6-4, which worked out just fine. The Goblin achieved a decent altitude, and best of all, stayed within the confines of the field. It will fly again - but probably not on a D12. I don't like to walk great distances to recover my models anymore - that was for my younger and slimmer days.

The Bat spreads its wings (Click to enlarge).

And returns gracefully to Earth
(Click to enlarge).

My last flight was reserved for the clone of the Estes Bat, which took to the air on an A8-3. I really like this rocket, even if the bat wing shaped fins are kinda fragile. Fortunately nothing broke when it touched down, and the Bat now sits proudly on the shelf, having survived yet another taste of freedom.

I mentioned there were some highlights to the day - besides my flights, which naturally are always notable. Allen's Estes Sky Dart II put on a great show with its slow, spiraling glide, Vince's beautiful Skonk Wulf pleased everyone with a textbook flight on a D12, whereas his Halloween Battle Axe rocket went up ok, but came down in two pieces after the shock cord separated. It was also a not-so-good day for gliders - Allen's eRockets Sabre parasite glider was last seen heading to the North Pole, Brian's competition glider was a bit underpowered on an 1/2 A, and Vince's Edmonds model shredded when it caught on the igniter clips on liftoff.

Vince's Skonk Wulf starts its journey (Click to enlarge).

Allen's Sky Dart II doing its thing
(Click to enlarge).

Vince's Halloween Battle Axe rocket
(Click to enlarge).

Estes Riptide under chute (Click to enlarge).

Vince's glider shreds (Click to enlarge).

It was a glorious way to spend a couple of hours on a lazy Sunday. It is great to be flying again!

Outreach day for HARA...

Today was a reasonably busy day for members of my club. It started bright and early at 9 AM, when Vince and Allen gave presentations on rocketry fundamentals to mentors and mentees of the 100 Black Men of Greater Huntsville. There were about 20 present in this virtual Zoom meeting, and I must say Vince and Allen did fantastic jobs - they managed to make boring math and concepts quite interesting. Vince used his Halloween rockets to illustrate some basic stability concepts, whereas Allen invoked personal experience and some basic problems to help the kids understand things like thrust to weight ratio and how total impulse factors into rocket altitude. Those attending appreciated the talks, and I'm pretty sure they all learned a thing or two. Good way to start the day.

Then Allen showed up at my place around 11:15 to load rockets and gear for our next event. We had agreed a few weeks ago to help a group of local scouts learn rocket basics by conducting a build and launch session down at St. Johns Episcopal Church. I raided my stash to provide 23 Estes Generic rockets and a Blast Off Flight Pack containing 24 A8-3 motors, igniters, and wadding. As the scouts would need to first build the rockets they would fly, I also scrounged up a few bottles of Aileen's Tacky Glue, rulers, pencils, scissors, and hobby knives. Last to be loaded was my new launch rack and controller, which can launch up to 5 rockets - this would be its inaugural launch, and I was pretty excited about putting this equipment to use.

Hard at work building Generics (Click to enlarge).

We arrived at the Church around noon, where we met Vince and Art. I had originally thought that me and Allen could handle this event by ourselves (after all, it was only 20 scouts), but we soon found out that Art and Vince's help was more than optional - it was required. The Generic builds progressed somewhat chaotically - we really needed more glue, pencils and scissors - but thanks to my club mates, some capable scout leaders and attentive parents, the job got done without any major problems. The big lesson learned for me was to have a bottle of glue and tool set for every two rockets, not every four like I did today. Too many kids were waiting on glue and pencils, which slowed things down.

Vince helps cubs load their rockets (Click to enlarge).

The pads were set up on a small field immediately south of the church, and it was less than ideal - there was a creek on the west side, a major road on the east, and high voltage power lines running diagonally across it. We chose a location that would hopefully maximize the chances of getting the rockets away from the hazards, and advised the scouts that maybe they should utilize "nose blow" recovery, rather than go with a parachute that could easily have the rocket drift into a bad spot. Most heeded this advice, though there were a few that opted to use a chute.

A Generic lifts off (Click to enlarge).

Up, up, and away! (Click to enlarge)

18 Generics took to the air on A8-3 motors, and we got 18 back. There were only a couple of igniter problems, and even the rockets that had parachutes stayed on the field and avoided the power lines. Needless to say, we had quite a few happy scouts and I also was pretty pleased, as my new launch gear performed very well. We closed out the launch by flying Vince's Target Halloween bowl saucer on a C6, after which we packed up. Art, Allen and I caught a late lunch at Red Robin, where we engaged in a wee bit of rocket talk before returning to our residences.

Always nice to be appreciated!

Good talks, perfect weather, and a little rocket fun with the scouts - all in all, a nice outreach day for HARA!

3 more Generics in the fleet...

 

New fleet members (Click to enlarge).

I just finished "building" 3 more rockets based on the Generic fin can - the Generic (can you believe I have never built one of these "stock"?), the 1472 Scorpion, and the 2026 Athena. All of these are original kits, though I did have to replace the damaged body tube of the Scorpion, which was crushed in shipping. Not a big deal, as it was necessary to fill and paint the body tubes to get rid of the very visible seams. So these E2X "quick builds" took a bit longer, with all the filling, priming, and multiple coats of paint. The results are seen in the photo above - not too shabby, even considering the peel n' cuss stickers that are used to decorate these models.

Generic motor mount assembly instructions (Click to enlarge).

A quick tip on the Generic - the motor mount slides into the fin unit, and is held in place by a thick cardboard coupler in the front and a small thin cardboard centering ring on the motor tube (which also holds the motor hook in place). This is good enough to keep the mount from sliding back and forth, but there is a fairly wide gap between the motor tube and the inner wall of the fin unit - which makes it easy for the motor tube to be tilted with respect to the rocket centerline. To prevent this, glue a split BT20/50 centering ring even with the rear of the motor tube, which makes a snug fit in the back. Adds a little weight, but the motor tube will be held straight, eliminating off axis thrust.

You can get split BT20/50 centering rings from eRockets here: AR-2050S

Or you could cut them yourself - I'm kinda lazy, so I buy them precut.

Lightning is coming!

Last year Quest/Aerotech released their line of 18mm Q-Jet composite motors, which were a welcome addition to the stable of model rocketry power plants. The C12, at 9.8 newton-seconds, is a full C (the Estes C6 has an impulse of 8.8 newton-seconds) and has an average thrust over twice that of the C6 - nice for lifting heavy rockets. The D16, on the other hand, is a "baby D"; its impulse of 12.4 newton-seconds is quite a bit less than the power offered by the Estes D12, which also has a higher maximum thrust. But the D12 is 24mm in diameter, so you ain't going to put one of those in a stock Big Bertha.

I like the Q-Jets and have quite a few of them in my motor stash. However, the Q-Jet motors emit black smoke, akin to the Aerotech Smoky Sam or Black Jack composites. This is OK, but I like to see fire coming out of the nozzle - makes for better photos! Rumors had it that Aerotech was in the process of developing more Q-Jets based on the White Lightning propellant mix, and this got me excited. I love White Lightning motors - they emit a brilliant white flame and produce quite a bit of noise. They command attention at every launch in which they are flown.

Well, the rumors are now close to reality. Aerotech/Quest has submitted the White Lightning Q-Jets for certification, and Gary Rosenfield has posted some information on the forums. The new motors will be a C18 and a D20, both of which feature relatively flat thrust curves with short burn times and high thrust. The C18 has an average thrust of 19 newtons and a thrust duration a tad over 0.5 seconds, whereas the D20 has an average thrust of 18 newtons and a burn time of 0.76 seconds. It also has a peak thrust of 25 newtons at the beginning before settling down to its 18 newton plateau. 

Here are the thrust curves (from thrustcurve.org):

The packaging is also very attractive:

But the best thing is going to be the fire and noise! Gary posted this image on Ye Olde Rocket Forum of an Estes rocket powered by one of the new White Lightning motors:

Take my money, please!