My first Geezer TARC rocket for 2018...

I was suffering from rocket burnout last year at the time of the release of the TARC rules, so I did not get around to building my Geezer TARC rocket until the latter part of Summer. Normally I build two to maximize my chances, but I started so late that I could only complete one before the launch. I have determined I shall not repeat last year, so I got to work designing as soon as the rules for TARC 2019 came out earlier this month. Four completed designs are now stored on my computer, but I am only satisfied that one - christened the Reliant - is sufficiently well thought out to construct. Another will make the grade soon enough, but it'll take a little more work with Open Rocket.

Open Rocket visualization of the Reliant - still trying to decide decor (Click to enlarge).

So what am I looking for in my Geezer TARC entrees?

1) Simple and relatively easy to build - hard to cut straight with my eye condition, so I need fins with simple geometries, like swept trapezoids or deltas. No elliptical shapes, even though those are less draggy.

2) BT-70 based - BT-80 tubes have too much area, hence too much drag (remember we are trying to get to 856 feet this year, 56 feet higher than last year's mark). Centuri ST-18 tubes are "minimum diameter"; a regulation size egg will barely slip into them, but there is no room to pad the egg sides. OK if you land nose down, but bad if you hit on the side of the capsule, especially with 3 eggs inside. A BT-70 is a good compromise between the two. Another plus is that Apogee makes some relatively lightweight egg protection for this tube diameter.

3) A weight around 520-525 grams fully loaded without motor - The fact that this year's rockets have to be painted means added weight. Throw in the additional egg and higher altitude and you may find it extremely hard to make altitude with a BT-80 based bird. Too much drag, too much weight.

4) Assuming the weight range above and a typical rocket drag coefficient of about 0.75, a F motor should get me to about 850 feet. Open Rocket has the model going about 150 feet higher, but it always over estimates altitude.

1st-order altitude prediction for the Reliant (Click to enlarge).

The Reliant meets all these criteria. As you can see from the Open Rocket screen capture, it is very classic, very simple. The fins are balsa laminated with paper to keep weight low and increase durability, and the payload (capsule) section can be loaded from both the front and back to help in getting the eggs in and out - hopefully without breaking. The balsa coupler at the base of the capsule is augmented by a JT70 coupler wood glued to the front to help facilitate insertion of the Apogee 2 egg foam protector, and to add a little strength back there. A hardwood dowel will be glued into the back of the coupler, and the screw eye will be inserted into the dowel. That point - to which the dual parachutes are attached - will take a lot of stress at ejection, and I do not want the screw eye pulling loose (which would make me a prime candidate for the Flying Pig trophy). The rocket is powered by a single 24 mm composite, which is retained by the Estes plastic 24 mm screw-on retainer (available in 3 packs online).

Open Rocket design of the Reliant (Click to enlarge).

As I stated near the beginning of this post, I am pretty confident in this design - so I had to build it. The construction went quickly, and here she is, ready for primer when the stormy weather leaves. Getting started this early gives me the time to work up and build another design, probably a cluster of some sort. I am ahead of the game!

Reliant ready for primer (Click to enlarge).

And I am going to win this year... Mark these words!

I attend rocket camp...

Campers hard at work on a 3" BMS School Rocket (Click to enlarge).

I had the privilege of attending the Hope Christian Academy Rocket Camp this past Friday. Imagine 9 highly motivated kids spending a week devoted totally to rocketry - they covered a great many aspects of the hobby, progressing from stomp rockets to water rockets to model rockets to mid power birds. Along the way they learned the basics of rocket physics and how to use Open Rocket to design their own models. By the time I showed up Friday morning, they had advanced sufficiently far to breeze through the construction of the Balsa Machining 3" School Rocket, and were eager to show me some of their Open Rocket designs. To say I was impressed would be an understatement - one student knew Open Rocket better than I, and he revealed a beautifully rendered simulation of a rocket resembling the old Centuri Taurus. Several of the class plan to be on the Hope Rising TARC team, and so there were also some designs for this year's TARC rocket. It will be interesting to see which one makes the final cut (the team, when assembled, votes on the design that will be used during the season). I thought it appropriate that the members of the camp referred to themselves as "RPGs" (Rocket Powered Geniuses) - they even came up with a camp logo:

My rendition of the Hope 2018 Rocket Camp logo (Click to enlarge).

My progress on builds has been good - I have finished the first rocket on my 2018 build list, a clone of the Centuri Javelin. The Javelin was my first rocket, built and flown 50 years ago, and I had to have another one to commemorate the anniversary. The build was very straightforward, and it marks the first time I have used decals made with my inkjet printer. Past efforts with inkjet decals were pretty ugly, and so I resorted to printing my decals on the color laser printer at work. However, the colors are not as vivid as I would wish, and the toner is often low, so I thought I would try printing with my new HP Envy. The decals came out well, with better color saturation - A successful experiment for once!

Centuri Javelin clone in 1971 catalog decor
(Click to enlarge).

I have started construction on my first Geezer TARC rocket for 2019  - details to follow in another post.

Time to start Geezer TARC!

OK Geezers, now that the rules have been released for the 2019 TARC competition, we can start the annual Geezer TARC contest. This year promises to be fun-filled, with 3 eggs, 3 parachutes, and an altitude goal of 856 feet. I'm looking forward to it!

So here are the rules for 2019 Geezer TARC competition:

The rules are the same as those for the 2019 TARC challenge with the following exceptions:

• Geezer TARC begins with the announcement of the 2019 rules in May (which happened today) and ends with the contestants’ rockets being launched at a single event (date TBD, probably on a Saturday on or near the start of the college football season in September).
• Each contestant may enter up to two rockets. These rockets may not fly before the official launch date, and the score shall be determined by the first flight of each on that date. The contestant's score shall be the better of the two flights, or the score of one flight if only one rocket is entered.
• Contestants must use one of the regulation TARC altimeters (APRA, PNUT, or Firefly) as the "official" measure of altitude. A re-flight will be allowed in the event of an altimeter malfunction, provided the flyer can demonstrate it was not his or her fault (i.e., did not forget to turn it on or provide vent holes to the outside). The altimeter used to record altitude may be used for no other purpose, though the use of a Jolly Logic Chute Release or other altimeter type/flight computer is permitted for flight control.
• There is only one rocket per design, and there are no test or sub-scale flights permitted for the design. Its merit will be judged solely by the rocket’s performance at the contest launch. If two rockets are entered, they must be of substantially different design - different number of motors, fins, or something major - an inch shorter or taller does not constitute a substantial difference, nor does the same design at a different scale.

Good luck everyone!

Odds and ends...

The weather here in Huntsville is heating up as summer approaches; alas, I have not been able to take advantage of the recent favorable conditions by launching rockets, except for three I put up in a school demo. My colleague, Chuck, had arranged with Williams P-8 school to do a rocket lecture/launch for their science week. Unfortunately, he broke his ankle at the NASA SLP (Student Launch Project) launch, making it hard for him to easily get around, much less set up and conduct a launch. I  responded to his call for assistance - I'm always looking for a reason to ditch the innumerable meetings at work - and so 9 AM Monday morning saw Chuck giving a talk to a bunch of 5th graders while I set up my pad on the track field of the school. My launch gear goes together in less than 15 minutes, so I sat down on a bench after placing the first rocket - an Estes ARTF Rookie - on the rod. While checking my email on my phone, I happened to look up and noticed this little bird sitting right on the top of the 1/8" rod, in direct line of fire of the Rookie. Amazed, I moved closer, snapping pics with my phone camera as I approached, hoping to get close enough to get a really good image of this unusual occurrence. It was not to be so - the bird flew away when I was about 40 feet away, too far for the iPhone to get a decent pic. All I got was a few blurry images - How the heck the bird was able to perch on the tip of that skinny rod is beyond me.

Estes Rookie on pad (Click to enlarge).

Bird perched on the rod (Click to enlarge).

Anyway, the demo launch went well. The Rookie put in a fine performance on a B6-4; it was followed by the Estes Meteorite White Crayon, also on a B6-4. The final bird to take to the air was my Quest saucer, powered by a C6-0, after which Chuck amazed the crowd with some of his aerobatics with an RC plane. Several of the kids seemed very interested in the rockets, and asked some pretty good questions about stability and how the rocket motors worked. A good morning, except that I had to return to work.

I managed to finish three models this past week - the clone of the Estes KL-3 Marauder, a Centuri Payloader clone, and a clone of the Centuri Mach 10. I am very happy with the Marauder and the Mach 10; the Payloader seems a bit bland, and I may swap the black trim for the 1964 decor, which featured a checkerboard pattern and the kit name. I have also completed building the clone of the Centuri Stellar Starlifter - after a final sand, it'll be ready for primer. The Javelin is ready for paint, and the Shrox Sniple needs the gray primer sanded off before getting a coat of white primer.

KL-3 Marauder (Click to enlarge).

Centuri Payloader (Click to enlarge).

Centuri Mach 10 clone (Click to enlarge).

Lots to do this weekend...

Sunday morning launch...

The Longshots begin unpacking their equipment for practice (Click to enlarge).

The weather was practically perfect this past weekend - not only did I get rockets built (Centuri Stellar Starlifter), primed (Sniple), and painted (Mach 10, Estes KL-3 Marauder), but I also got to fly a couple during the Longshots' TARC practice on Sunday. Duane and I showed up at Pegasus Field around 10 AM, whereupon I started to set up the low power pad and Duane began grilling his finals-bound team. It is good to have the "benevolent dictator" back in the States; things were kinda quiet at Pegasus without him. Having been gone for 5 weeks, Duane had a lot to catch up on, and the Longshots were eager to show what they had done in his absence. I was happy to see a green and white backup rocket next to the red and white "Phantom Flier" on the prep table - always a good idea to have a backup at the TARC finals. The Longshots made two flights, striving to hit an altitude of 775 feet. The first, involving the green and white rocket, clawed its way to 717 feet, but the trusty Phantom Flier missed the mark by only 4 feet, reaching 771 feet. Pretty good, but they need to work on their durations a bit in the wind - their time on the second flight was way long (56 seconds).

Patrick inspects "Sign Here Please" (Click to enlarge).

 We were joined on the field by Patrick, a new member of HARA. Patrick brought with him a scratch orange and white rocket, "Sign Here Please". "Sign Here Please" featured 3D printed fins, nose cone and motor mount; it would make two flights on Sunday, both on Estes F15 motors. The first flight went well, with the rocket slowly ascending into the blue sky and deploying a colorful chute a bit past apogee. The second flight, not so much, as the model arced over right after leaving the rail and followed a flat trajectory to the northwest. Breaths were held as the rocket nosed towards the ground, but the ejection charge deployed the parachute at the last minute, saving the model from a ballistic impact. I figure the F15 did not provide enough thrust to weight to get the rocket moving fast enough off the rail - the first flight was lucky to have occurred during a lull in the wind. An F32 or something like it would be better for "Sign Here Please"; 3D printed parts are heavy beasties.

"Sign Here Please" leaves the rail (Click to enlarge).

Coming in for a nice soft landing (Click to enlarge).

I packed two rockets for this launch - an Estes Meteorite White crayon and my recently repaired Probe-18, its payload section loaded with two altimeters. The Meteorite White was the first rocket to fly on Sunday, reaching maybe two hundred feet on a B6-4. Recovery was nominal, with the orange ripstop nylon parachute softly landing the model in the field. The Probe-18 was also powered by a B6-4; the purpose behind Sunday's flight being to compare the data recorded by my Altus Metrum Micropeak and Adrel Alt-BMP altimeters. The Adrel is a new addition to my electronics collection - measuring less than 1x2 centimeters, it is the smallest recording altimeter I have, and was designed for use in rocket competitions. The flight was picture perfect, with a good landing under chute.

Meteorite White leaves the pad (Click to enlarge).

Probe-18 starts another flight (Click to enlarge).

I am always amazed by modern tech - As we waited for the Longshots to make their final flight, Patrick and I were able to use our phones to watch the live stream of the Blue Origin New Shepard launch to the edge of space. Mannequin Skywalker got a fantastic trip to 350,000 feet, and I shook my head in awe at the spectacle of the booster landing. Truly great things are happening!

The New Shepard booster touches down on the pad (Click to enlarge).

Back at the apartment, I plotted the data from the Adrel and Micropeak altimeters on the same graph. I did not expect an exact match, but was surprised by the 4 meter difference in peak altitude, and the 7 meter discrepancy during the descent. Gonna have to think about this a bit, as both units shared the same payload section.

Comparison of Adrel data to that of the Micropeak (Click to enlarge).

To close this post, here are a couple of screenshots from altimeter software - the Micropeak works on multiple platforms, while the Adrel application is Windows-only. An unfortunate thing that altimeter manufacturers have in common is that they don't update their software as the operating systems go though major updates, which can cause issues. The Adrel software was a pain in the rear to install under Windows 10, though I see a new version was released back in January (I installed an older version in December) - maybe it makes things easier. The Micropeak app also had issues under High Sierra on my Mac - I had to disable a security feature to get it to run. Sigh...

Micropeak summary screen (Click to enlarge).

Adrel summary screen (Click to enlarge).

Building the Shrox Sniple - Part 2, Construction and finishing...

There are no instructions for building the Sniple, but it is very straightforward - only thing that is different from a "standard" rocket like the Alpha is that you have to note that the forward fins are 4" from the rear of the body tube. My build proceeded as follows:

• An 18" length of BT-50 was cut to 13", using the Estes tube cutting guides (very handy for quickly cutting Estes tubes). The tube spirals were filled with water-thinned Fill N Finish and allowed to dry until late afternoon of the next day.

• While the body tube was drying, the fin patterns were printed out on card stock. A 6" sheet of 1/16" basswood was sanded smooth using 400 grit sandpaper, and three of each pattern traced, making sure the grain was parallel to the leading edges. The fins were cut out using a sharp hobby knife, and the non-root edges rounded using 240 grit sandpaper.

Assembled Sniple motor mount (Click to enlarge).

• The motor mount was assembled (an Estes BT-20J, Semroc AR-2050, Semroc AR-2050S, and a standard 18mm motor hook). Most folks use some sort of tape around the middle of the tube to help hold the hook in place, but I cut a strip of card stock and glue it around the tube; I find this to be much more durable than tape. A length of kevlar thread was tied to the motor hook and run through the upper centering ring - the sewing elastic shock cord was then tied to the end of the kevlar thread. To avoid "Estes dents", my shock cords are always at least twice the length of the rocket.

Sniple body tube with spirals filled (Click to enlarge)

• After they had dried, the tube spirals were sanded smooth using 240 grit sandpaper, and the motor mount glued into the body tube. I used the spiffy Qualman Rocketry fin alignment guide to mark the fin and launch lug lines, which ran for 8" from the rear of the tube. A strip of card stock was used to draw a line around the tube at the 4" mark - this served as a guide for placing the rear of the forward fins.

BT-50 Qualman Rocketry fin guide for 1/16" fins (Click to enlarge).

• The fins were glued on using Aileen's Tacky Glue with the double glue joint technique. The Qualman guide functioned as a jig to insure proper alignment of the fins - it's quite a versatile tool. After the glue dried, fillets were created using 3 applications of Titebond wood glue smoothed with a finger.

• 4 coats of Brodak sanding sealer were brushed on, sanding with 400 grit after coats 2 and 4. At this point, the basswood fins were smooth as glass, and ready for primer and paint.

As of this writing, the Sniple has just been sprayed with the first coat of gray Krylon primer. I will wait a week to give it plenty of time to dry in the Southern humidity, sand most of it off, then hit the model with a coat of white primer. I will pick up this build thread when I have started the painting.

Ready for primer (Click to enlarge).

Building the Shrox Sniple - Part 1, Getting started...

Anyone who has been into hobby rocketry for a length of time has heard of Douglas Shrox - "The Master of the Dark Art of Rocketry". Shrox is legendary for his exotic designs, many of which have been turned into kits offered by Apogee, e.g., the Orion, the LexJet, the Sea Sting, the Stonebreaker, etc, etc. There is also some of his work published in the Apogee Peak of Flight newsletter, free for download; however, you need RockSim or Open Rocket (which can import RockSim files) in order to open the designs, extract the parts lists, and print out the fin patterns. I particularly liked the Bolaero, an Earth defense missile, and built it several years ago - it flies great! The downside to all this is that some of the plans (like the Tarmon) are missing, having fallen into Internet voids over the years. Hopefully they can be recovered by some enterprising sleuth.

The orange Rustoleum paint I applied to the Marauder yesterday did not turn out so well - I have some bubbles and a "cottage cheese" problem on the lower body and a couple of fins, which means sanding and more paint later on in the week when the current paint is fully dry. Feeling a bit frustrated, I sat down at the computer and started looking for something else to build. Nothing on my kit list appealed to me (though I should have considered the Trident or Starlight, which are on the 2018 build list). However, I did run across a Shrox design - the Sniple - stashed away on my hard drive, which caught my imagination with its Asian missile looks.

The Shrox Sniple (Click to enlarge).

I noticed that the Sniple had rather small fins, with one set being located fairly far from the rear of the rocket - not very stable. Sure enough, the RockSim file showed almost 30 grams of nose weight to insure stability, which means it's gonna fly like a pig - only about 180 feet on an A8-3. I also noticed that all that weight gave about 5 calibers of stability, so I kept reducing it until Open Rocket showed about 2 calibers with a C6-5 loaded - which occurred with 10 grams added to the nose. Much more reasonable, and a nice improvement in altitude. Still, I didn't quite trust the results - the rear fins look very tiny - so I loaded the modified file into RockSim, which produced a near match to the Open Rocket results. I feel better with both programs saying the model is stable, but the proof will be in the flying.

The Sniple in Open Rocket (Click to enlarge).

It's raining all day today, so I am gathering the parts to start building this little beauty. It appears to be the perfect project to occupy my time over the next couple of rainy evenings. If anyone else out there is looking to build something from scratch, I heartily recommend one of the Shrox designs (see post 65 in this thread) - they are very cool fliers!

Open Rocket visualization of the Sniple (Click to enlarge).