The hours before...

Today is clear and comfortable, with light winds out of the NNE - perfect for the Geezer TARC launch in a few hours...

Ready to compete!

I'm all packed up, with altimeters charged, eggs weighed, rockets loaded with parachutes, and low power pad/controller bagged for use by the modroc flyers. So why did I fret last night, and why I am still fretting?

Because I have doubts about the parachute sizes I have chosen for the payload section, that's why! I woke up in the middle of the night and revisited my descent rate calculations using three different utilities - 2 online, and the app on my iPhone. And I'm still reviewing them this morning, wrestling with the basic issue, which is that all the numbers indicate my chosen 12" parachute size is marginal for the challenge, producing a descent rate of around 23 feet per second. A tad too fast, but the next commercially available size - 15" - would definitely keep the eggs up there way too long. I am wishing I had the talent/ability/motivation/etc. to make my own rip stop nylon parachutes, because I sure could use a couple of 13" diameter hexagons right now. Alas, it's too late, and I'm going to have to make do with what I've got.

Top Flight parachute compared to that from BAMA (hexagon vs. octagon)

To show you how nervous I am, I opted to use some new parachutes I ordered from BAMA Recovery Systems instead of my tried and true Top Flight brand. The BAMA chutes are octagonal in shape, with 8 long shroud lines instead of 6 - this supposedly increases the parachute drag coefficient, slowing the descent. I'm a) hoping this is the case and b) they can take the stresses that are going to happen with that egg capsule is ejected from the sustainer. It'll be very sad and messy if those shroud lines break.

I'm also second-guessing my motor choices, but that's normal before a Geezer TARC launch. We'll see how things go on the field.

Stay tuned...

Another Boy Scout rocket...

I just finished the Estes "Space Exploration" Boy Scout rocket, which I bought in a bulk pack from the Boy Scout store (Scout Shop) many moons ago. It was a great deal - 6 rockets for $30, including shipping; unfortunately, this product has been discontinued, with the only offerings being standard Estes fare. The reason is pretty clear - Estes has stopped producing the Ricochet, and the Space Exploration rocket was nothing more than a Ricochet with different stickers. So it went bye-bye with the Ricochet.

The kit parts are good Estes quality - laser-cut fins, nicely fitting plastic adapter and nose cone, and decently strong body tubes. I would rate this build a definite skill level 2, as you have to line up the three components making up the fin. This is more tedious than hard, but it does require that you pay some attention to what you are doing. Finishing was straight forward - 4 coats of Brodak sanding sealer on the fins, then a couple of coats of primer followed by the paint. I screwed up the paint scheme by relying on my failing memory, for if I had bothered to take another look at the box art, I would have seen that one fin was red and the others blue. My memory had all four fins blue, and that's how she was painted. The stickers went on easily, but appear shiny against the paint - you can tell there are stickers on the model. Why can't Estes just give us waterslide decals, which look so much better? I know - stickers are easier for young ones to handle, but they all too often look crappy to us old geezers.

Boy Scout "Space Exploration" rocket (Click to enlarge).

Anyway, the rocket turned out OK, as you can tell from the pic. A bit of trivia for you non-Scouts - the circular logo beneath the American flag is a replica of the Boy Scout Space Exploration merit badge. I thought it was kinda neat that they managed to incorporate that into the kit.

Now it's back to assembly line - I have to apply the second primer coat to the lower part of the Artemis (my 2nd Geezer TARC rocket), build an egglofter for the NRC Eggloft Duration event, and finish assembling my Apogee tower. Gonna be a busy weekend...

Time to do some TARC math!

Now that the Reliant is finished, it's time to figure out the size of the parachutes needed to land the booster and payload sections safely. To do so, you need to measure the weights of both these sections, which in my case are 178 and 318 grams, respectively. The booster is easy, as one can choose the descent rate and size the parachute accordingly. A "safe" descent rate - one that avoids damage to the fins - is usually around 15 feet per second, so we go to one of several handy-dandy parachute descent rate calculators available on the Internet - I use either Model Rocket Parachute Descent Rate Calculator or Descent Rate Calculator - Rocket Reviews or an app I have on my iPhone. All 3 give similar results, so the choice does not really matter.

But, wait... Why can't we just use Open Rocket, as that's the design program? It gives descent rates, doesn't it?

Yes, but Open Rocket cannot handle the case where the payload section comes down separately from the other section. So what it will give you is a descent rate based on the sum of the areas of all your parachutes and the total weight of the rocket. That's not going to work this year. So we are going to have to do things outside of the simulator. If you use Rocksim, you can trick it into handling this year's TARC circumstances by creating a 2 stage rocket and designating the payload section as a motorless upper stage; you can then attach a recovery device to each stage and set the deployment circumstances. However, most folks don't have Rocksim.

Now I'm ready to do the compute the booster chute size, so I bring up the RocketReviews calculator and put in the booster weight. I prefer to use Top Flight thin mil rip stop nylon parachutes, which are hexagonal in shape, so I choose "hexagonal" from the Parachute Shape drop down menu. Just for grins, I put in the altitude goal of 856 feet, and finally make a guess at the right parachute size before I click the "Submit" button:

Click to enlarge.

It appears that my initial guess of 15 inches was too small - the calculator is recommending a parachute size of 18 inches. Recalculating with this value yields

Click to enlarge.

This is pretty close to my desired descent rate of 15 feet per second, so I'll run with it. My booster parachute will be an 18" Top Flight, bright orange in color.

Now for the harder part - the two identically-sized parachutes attached to the payload section carrying the eggs and altimeter. To calculate this, we must first figure out the required descent rate to land the payload section 43 to 46 seconds after liftoff, which means we have to go to our simulations to get the time of ejection, and subtract that from the duration goal to get the length of time the parachute is deployed. Open Rocket tells me that it will take about 7 seconds to reach 856 feet, so I will subtract that value from the midpoint of the duration goal - 44.5 seconds - to get the parachute time. The descent rate - in feet per second - is simply the altitude (856 feet) divided by the parachute time (37.5 seconds), or

So we need 2 parachutes that will lower the payload section at 22.8 feet per second. Now I go back to the descent rate calculator and put in the weight of the payload section, keeping everything else the same:

Click to enlarge.

Turns out that 18" is pretty close, with a descent rate of 22.6 feet per second. If I fiddle a bit, I end up with a parachute size of 17.8".

However, I need two parachutes, not one, so how do I do that? What I need to do is divide the area of the above by 2 to get the area of each identical chute. Since area goes as the square of the diameter, this means I must divide the diameter by the square root of 2 to get the size of my chutes. Doing so gives me a diameter of 12.6". I can check my work by doing a comparison:

which is close enough for government work.

Trouble is, there are no 12.6" commercially available rip stop nylon parachutes. The closest match is the 12" diameter. So what happens if I use that? Well, 2 12" parachutes have a scaled area (I'm leaving out the factor of pi) of 288, which translates to a diameter of square root of 288, or 17.0". I can now plug this value in into the descent rate calculator, which gives:

Click to enlarge.

This shaves about 1 second off the time, but it is still within the allowed duration range. Quite acceptable, especially given that I really don't want to have to learn to make nylon parachutes. Therefore, Reliant's booster will be recovered by an 18" parachute and the payload section will be brought down by two 12" chutes.

This concludes today's TARC exercise.

3 done.....

The wet summer continues, but I have managed to find brief periods of lower humidity (between 45 and 50%) to get some final painting done. First up is the clone of the Centuri Stellar Starlifter, painted bright blue and white - the "challenging" decor mentioned in the instructions:

Centuri Stellar Starlifter (Click to enlarge).

The only thing challenging about this build - a snap with Semroc/eRockets laser-cut fins - was the application of the blue Testors enamel. It blistered, necessitating a major sanding and re-coat. That one applied OK, but it reminded me how much I hate dealing with enamel paints. I have very poor luck with them. The orange horizontal stripe decals also turned out to be a bit translucent when applied to the blue body tube, which turned the orange into a brown hue. I'll leave them in place for now, but am seriously thinking about replacing these decals with a couple of pieces of orange pinstripe tape.

My 1st Geezer TARC rocket, the Reliant, received its final coats of paint and markings. The name I ginned up in a graphics program and used the Cricut Maker to cut it out of black vinyl. The black roll pattern on the payload section is made of strips of black chalkboard paper, also cut by the Cricut. It turned out pretty nice, and I was surprised that the model came in over 50 grams under weight, which may force my motor selection to a F30J, rather than a F32 (Open Rocket says the Reliant will go about 300 feet too high). The F30J yields a margin of about 50 feet, which is kinda small - I will have to import the design into Rocksim and see what altitude it gives me.

Reliant (Click to enlarge).

I also played some more with applying decals to OpenRocket designs, and was able to replicate the Reliant fairly well, even down to the fin art. The only downside is that Open Rocket insists on putting the decal on both sides of the fin, which isn't the case for the actual model. Still, I am pleased with the result, and am liking Open Rocket more and more for conventional designs. The only thing I wish it had is a drag coefficient override, like that in Rocksim. It would be nice to put in a numerical value, rather than messing with the drag by altering the finish of the rocket (smooth paint, unfinished, etc). That's clunky, and too coarse for serious work.

Virtual Reliant rendered by Open Rocket's photo studio (Click to enlarge).

Finally, I completed my first competition build in decades, the 1/4A parachute duration rocket, which comes in at 7 grams without the chute and motor. That's probably about 3 grams too heavy, but 1) I suck at parachute packing and needed the extra room of an 18 mm tube, rather than going with the straight minimum 13 mm diameter structure, and 2) I could not resist spritzing on a light coat of paint, which added about 0.5 grams. However, it is an improvement over my competition birds of yore, and I am looking forward to seeing this little puppy fly at Pegasus.

1/4 A Parachute Duration rocket (Click to enlarge).

Miscellany...

It's been a few months since I last flew, and I am feeling a bit restless. Unfortunately, Pegasus field is way overgrown with weeds - won't be cut until fall - and HARA is still awaiting our first launch at our new HPR field, which also won't occur until September or October. So I am kinda out of luck, unless I can locate a free spot of ground for a quick launch fix. In the meantime, I am going to have to content myself with building rockets, in anticipation of returning to flying in a couple of months.

So, what have I been doing?

1) Took advantage of a very rare low humidity weekend to apply paint to the Centuri Stellar Starlifter clone. However, I had trouble with the sky blue Testor's enamel (what else is new?) - the model surface has a sandpaper-like texture, which means sanding and a recoat. After I wait the requisite 3 days, naturally... Did I mention I hate enamels?

2) Applied primer to the Estes Boy Scout Rocket (rebranded Ricochet).

3) Applied the first coat of paint to my 1st Geezer TARC entry, the single motor Reliant. Gloss white is now on, color coats to come when the humidity drops once again. It should have already been finished, but the thought of sanding the primer off that big TARC rocket was enough to send me into a fit of procrastination. Only exceptionally good weather and the beginnings of schedule pressure could induce me into "gittin' er done" so I could move on to the paint. I really do hate sanding.

The Artemis - My 2nd entry for Geezer TARC (Click to enlarge).

4) Started building my 2nd Geezer TARC entry, the Artemis. It's a 4 motor cluster that resembles a Saturn. I had told myself I was not going to fall prey to the Apollo theme of this year's TARC, but in the end it was just too much to resist. I am pretty happy with the design, actually.

The Artemis as of Monday night (Click to enlarge).

5) Built my prototype 1/4A parachute duration rocket for the coming NRC season. I am trying to keep it as light as possible, but in a bout of senility, I primed it just like any of my other models. Duh... Now to sand the primer off, and hope that I can get a finished model well under 10 grams. After I finish this bird, I will move on to designing and building a prototype for B payload altitude.

My 1/4 A Parachute Duration prototype (Click to enlarge).

So still staying busy, but alas, no flying. Gotta find a field somewhere.

What to do on muggy summer days...

Midsummer is a frustrating time - the days are hot and muggy, with humidities 60% and higher - lately, MUCH higher. One cannot paint in such conditions, as the paint will "blush", causing the finish to appear blotchy. So my models patiently sit in primer, awaiting drier days. Which is not good, as I have a policy that no more than two rockets can be in primer at the same time, to avoid the overbuilding problems of the past. However, one cannot stay idle, so what am I to do? The answer came to me this past weekend - build some of the almost ready to fly (ARTF) or E2X kits in my collection. They are pre-painted and assemble in under an hour, so no adding to the backlog.  A perfect task for stormy summer afternoons.

ARTF or E2X kits are built using most of the standard build set - ruler, scissors, tape, hobby knife, and white glue. You don't need sand paper, and Plastic Weld is used to glue the plastic parts together and CA gel to join plastic components like fin cans to the body tube. Construction is quick and easy, and I put the models together while watching old movies ("Captain Blood", "When Worlds Collide"). Last weekend's builds were the MPC Duck Dodgers X-2 Invader and Cadet Cruiser, the Estes Banshee and Alpha VI, and an Estes-made Space Center Houston payload rocket.

MPC X-2 Invader and Cadet Cruiser (Click to enlarge).

I rather liked building the MPC kits - the body wraps are nice, with the X-2 Invader featuring Marvin the Martian, and the Cadet Cruiser sporting Porky the Pig's mug. The plastic parts are of good quality and fit well, with the only negatives being the flimsy motor tube, motor hook, and the hard plastic launch lugs, which seem to keep falling off the body tube no matter what glue is used (I finally fixed the issue with 5 minute epoxy). The shock cords were also way, way too short and had to be replaced.

The Estes Banshee build was straightforward - the only problems I encountered were getting the fins to adhere to the body tube with Plastic Weld (CA gel fixed this) and the fact that the orange stickers are too translucent for the black body tube. The Space Center Houston rocket went together with absolutely no problems, though I do not like the off-white payload section base - should be glossy like the body tube or blue like the nose.

Estes Space Center Houston Payloader, Alpha VI, and Banshee (Click to enlarge).

The Estes Alpha VI is the company's 60th anniversary model, sporting a candy apple red fin can and nose cone, along with a very prominent anniversary logo. However, the preprinted body tube was so flimsy that it had already begun to unwrap while still in the package, so I cut a matching length of BT-50, which I primed and painted gloss white. Consequently, this build took longer than 30 minutes, but if you discount the time I spent in readying a new body tube, it went super fast - the model was assembled in less than 15 minutes. 5 rockets finished in a weekend - not bad, and it definitely beats doing nothing rocket-wise.

Unfortunately the weather forecast indicates many more days of the same muggy weather - and I am getting low on ARTF/E2X kits to build...

Second time around...

My 30+ year old competition rockets (Click to enlarge)

During the first 25 years or so of model rocketry, the elite rocketeer was not one who had completed a level 3 certification involving a rocket propelled by a M class motor (such things did not exist, except in the wildest dreams of rocketdom). Back then, the "big boys" (and girls) were those belonging to the ranks of competition rocketeers, who built and flew models that tried to milk every ounce of performance from low power black power motors. In doing so, they made use of the lightest weight materials they could find - thin vacuform plastic nose cones, bakelite, vellum, and thin cardboard tubes, and 1/32" thick plywood fins of clipped delta or elliptical shapes. Rockets made from these were launched from rods using pop launch lugs, or towers, or pistons (used by the most driven competitors). The elite assembled in regional meets sponsored by NAR sections, vying to accumulate points for themselves, their teams, and/or their sections, keeping a constant eye towards the NAR's annual meet (NARAM), where the best of the best challenged each other. Winning the national championship was the epitome of the hobby in those years, and the rocketeers who did so earned it by sweat and tears (not much blood, save that caused by hobby knife cuts).

Summary of my first regional meet back in May of 1975 (Click to enlarge).

In my senior year of high school, I decided to throw my hat into the ring, and see how far my skills could take me up the competition ladder. So I built a couple of models based on the Estes Sprint and eagerly thumbed through each newly-arrived Model Rocketeer magazine, looking for a regional meet reasonably close by. In May of 1975, I got my chance - there was a regional, the Music City Competitors Annual Regional-1 (MCCAR-1), going to be held in Nashville on the 3rd and 4th of the month. I persuaded my dad to make the 2 hour drive to the launch site, where I joined about twenty other rocketeers under a canopy, waiting for the rain to stop. This happened about mid-morning, and I eagerly readied my streamer duration entry, loading an Estes B motor into the rear of the model and stuffing into the front the longest crepe paper streamer I could find. The model flew ok, and I logged a qualified flight duration of 27 seconds, which, amazingly was good enough to net me 4th place in A division. I also placed 4th in Class 1 Parachute Duration, so I finished in both events I entered - a good beginning, and I was pretty happy schlepping about in my waterlogged tennis shoes. I learned a quite a few lessons from watching the other rocketeers at MCCAR-1, some of which have stuck with me through the decades:

• Estes parts may get you an occasional win in duration events, but they ain't going to cut it in other event types. Build lighter.
• Ditch the launch lug - pop lugs are the minimum, and pistons or tower/piston combinations are best.
• Competition rocketeers are not so friendly during competitions - they are trying to ready their birds for a win, and usually don't have much time to chat with newbies. Also, bear in mind that you are potentially their competition, so don't expect helpful hints. Learn by watching, not by asking.
• Egglofting events have high entertainment value - especially the dual events. Lots of messes.

Competition Model Rocket (CMR) Rapier flown at NARAM-30 (Click to enlarge).

That was my one and only regional; I went off to college in the fall of 75, and used my free time during breaks to do sport flying. I did manage to fly at NARAM-30 in Huntsville (1988), where I sucked in a most supreme fashion. My only good thing about NARAM-30 was that it was my first introduction to what we now call high power rocketry, thanks to Matt Steele and his company, North Coast Rocketry. And so it was that my very weak attempts to participate in competition rocketry came to an end. Over the next three decades I read about competitions in the NAR magazines, noting that the ranks of competitors thinned out greatly over time, with the winner lists being dominated by the same people over and over again. And read about it was all I did - My reluctance to getting my butt kicked, plus the fact that the competition folks seemed to have gotten more unfriendly over the years, caused me to give it a wide berth. I'll take sport launches, with friendly and (mostly) happy folks flying for fun any day of the week.

Until now...

At last year's NARCON, I listened to a talk about the newly agreed upon revision to NAR competition. It sounded like NAR had finally gotten the message, creating a team of experts to breathe new life into competition flying. This panel established something called the National Rocket Competition (NRC), which consists of 6 events chosen annually from an approved list. These events are all low power, like 1/4 A Parachute Duration, 1/4 A Helicopter Duration, A Boost Glider, B Payload Altitude, B Eggloft Duration, and C Eggloft Altitude, which means they don't require a big flying field and can be done by anyone who can build an Estes kit - as matter of fact, Estes makes a couple of rockets that could be flown in this year's events (the B & C Eggloft and 1/4 A Helicopter Duration. The egglofter is way heavy, but it will at least turn in a qualifying flight). But the best thing about the NRC is that you no longer have to travel long distances to compete. All it takes are two NAR rocketeers (one of whom must be 21 or over) to set up and fly a NRC launch, after which the scores are logged onto a web-based national scoreboard, for all the world to see. You can fly any event as often as you wish, and can even specialize in certain events. I love this concept, even though I know a lot of old-school competitors are unhappy with it because a) it diminishes the importance of sections, and b) there are no craftsmanship events like scale in the NRC (even though a contest director may choose to have them as part of his launch). Change does not come easy, especially in the face of decades-old traditions.

I am going to give the NRC a try - It will give me a chance to work on some new skills, and enables me to fly competition events at Pegasus field with interested members of my section. That sounds like a lot of fun!

Did I mention egg lofting events have high entertainment value?

You can read more about the NRC here. Consider giving it a try!