Saturday, February 27, 2021

Picking up where I left off...

Back in the 70's, a lot of young rocketeers were members of the Estes Aerospace Club (EAC - see this post for more details). There were a couple of EAC specific kits (the Viper and Pegasus), a newsletter, a membership certificate, and - best of all - an iron-on EAC logo. As you advanced through the EAC, you received various colored "thrust bar" iron-ons, which you added to your T-shirt. This shirt became your badge of rank, and the rocketeers in my neighborhood wore theirs to every launch, showing off their rocketry prowess. You were ok if you had the blue thrust bar. Magenta wearers were scoffed at, and those with just the basic gold were ridiculed. I personally wore the green - the red was unattainable, as Camrocs, Cinerocs, and Transrocs were well beyond the means afforded to me by my allowance.

Estes Aerospace Club levels and requirements (Click to enlarge).

The EAC faded away as the many years passed; then, back in 2004, I discovered that the National Association of Rocketry had something called NARTREK, in which you advanced levels similar to the old EAC (except Estes kits were not required). NARTREK intrigued me... First, there was the name - nothing with 'Trek' in it could be bad - and second, it had been around for a very long time, since 1978. I wondered how I could have not known about it, given that it was prominently featured in Model Rocketeers of the late 70's. I guess I was so wrapped up in college, I neglected to properly read my rocket magazines. If I had, I would have known not only of the program's existence, but that the NARTREK name was not just NAR joined with last half of Star Trek, designed to appeal to us nerds. It actually stands for something, as you can see from the logo:

Well, ok, so there's a little Star Trek mixed in...

The NARTREK creators also did not like the program being compared to the EAC. NARTREK, they said, was designed to help NAR members advance their rocketry skills, preparing them to design safe rockets and to compete in competitions; it was not a gimmick to get young rocketeers to buy more kits. In the words of Chas Russell, the first honcho of NARTREK:

Model Rocketeer, December 1978, page 7 (Click to enlarge).

"ROCKET ON!" How could I not want to be part of a program like that?

And so I obtained my Bronze and Silver packs, and began my voyage through NARTREK. Bronze level was super easy - all you had to do was:
  • Make a 60-second parachute duration flight with a kit.
  • Make a 30-second streamer duration flight with a kit.
  • Fly a 2 stage kit.
  • Fly a kit with a D or larger motor.
Did all the flights in a single launch, filled out the forms, attached the 4x6 color glossy photos printed on my spiffy ink jet, and mailed the materials to NARTREK Base (ok, so there's a little more Star Trek). My Bronze certificate soon arrived, along with little bronze NARTREK logo decals to put on my rockets (badges of honor, I suppose).

My Bronze certificate (Click to enlarge).

I started Silver immediately - did the boost glider flight in February 2005 using an Estes Dragonfly (which was a very nice glider, BTW) and followed through with a cluster flight the following weekend (3 B6-4s in my Semroc Goliath). I was rolling!

Dragonfly on the pad before its NARTREK Silver flight (Click to enlarge).

Semroc Goliath stuffed with 3 B6-4s for a NARTREK Silver flight (Click to enlarge).

And then I just stopped...

Don't remember why - probably got sidetracked into some other part of rocketry (TARC maybe?). Anyway, I did not do the other 2 Silver flights (payload and scale) - NARTREK simply went out of my mind and stayed gone until this week, when I ran across my NARTREK packet in a pile of some old rocket papers. I had recently seen some posts on YORF about other rocketeers wanting to finish NARTREK, so I got to thinking that I ought to do the same. But 16 years had gone by - would I be allowed to pick up where I left off, or would I have to start back at the beginning? So I emailed George Scheil, the current NARTREK coordinator. He responded quickly and let me know I could pick up right where I left off, as if it were yesterday. He also informed me that I still had to mail in the paper forms with the photos.

I can't remember the last time I printed photos - probably back in 2004 for my NARTREK Bronze. Talk about nostalgia!

So I have added NARTREK Silver and Gold to my goals for 2021. Time to finish what was started many years ago. I have even located some old 4x6 sheets of glossy photo paper.

NARTREK - something every rocketeer ought to do, even if it takes them forever. Check it out here!

Sunday, February 14, 2021

Estes culls the herd...

The 2021 Estes catalog is now out - there are some pretty cool things in there, like an upscale, 24mm powered Mars Snooper (super excited about this!), a rather strange looking addition to the Space Corps line (the DARC-1) and the Antar, a new member of the signature series based on a non-flying model G. Harry Stine built back in the 1950's. The Antar looks awesome - I am eagerly awaiting this kit! Lots of goodies from Estes, and you can hear about them (and great offerings from other rocket vendors) in the NARCON Manufacturers' Forum posted here.

G. Harry Stine holding the Antar (Click to enlarge).

I am so excited about the new things in the Estes catalog that I never notice the discontinued stuff. Never notice, that is, until they become unavailable. However, folks over at Ye Olde Rocket Forum have pointed out that Estes has dropped over 20 kits this year, which seems like a pretty big number! So a few days ago I did a little research and put together a list of the discontinued kits (there's also one on YORF) - 23 in all:

This year's discontinued kits (Click to enlarge).

Some of these are not going to make rocketeers happy - the scale kits are quite popular with old  rocketeers like me. I kinda get the V-2, as there are a lot of these offered by other vendors, in all sizes. However, the Black Brant 3, the Nike Smoke and the Nike Apache are surprises, especially since Estes has been prominently advertising their line of scale models over the past year. I suppose sales of these kits were not so great, and ultimately we have to realize the Estes is a business. Poor sellers have to go bye-bye in order to make money.

So, in the midst of our celebration of the new arrivals, let us take a moment to mourn the dead. They will be missed...

Sunday, January 31, 2021

NARCON solves a mystery!

NAR's annual convention, NARCON, started on Friday afternoon and finished just a couple of hours ago. As usual, it was great - lots of informative and entertaining talks, good keynotes, socialization, and news from rocket vendors. But this year was special - COVID had eliminated the possibility of an in person NARCON, so the conference went virtual. This may have initially been met with trepidation, but the meeting was absolutely superb - not one iota decrease in quality - and best of all, a record 500+ people attended (as opposed to 100-150 for an in person NARCON). Not only was the attendance 4 times greater, but the virtual format had the advantage of eliminating one great problem experienced by past NARCON attendees. There are 3 parallel tracks, and you often had to make agonizing choices between two interesting talks held at the same time. This year, the conference vendor was making videos of the presentations available to attendees as soon as they were over, so you could go back at your leisure (up to a month from now) and catch up on the talks you missed. How cool is that!

Part of Saturday's NARCON schedule

So, what were the highlights? Well, I loved the manufacturing forum announcing the forthcoming goodies and the two keynote talks (on Osiris-Rex and commercial spaceflight). There were excellent video tours of LOC Precision, Kennedy Space Center, and the rocket capital of the world, Estes Industries. Among the talks, there was an outstanding video presentation by James Duffy on kit bashing common kits into works of art, some great tips on making and using decals by Randy Gilbert, and how to use and care for common rocket altimeters by Bernard Cawley. Because of the packed schedule I missed several good presentations, and I will be looking at those over the coming days. 

Alphas in WWII fighter livery (Click to enlarge).

Estes Explorer Aquarius with tanks painted to resemble freight cars (Click to enlarge).

And let's not forget Ed LaCroix's proposed logo for this year's NARCON...

Bernard's talk on altimeters solved a long standing mystery that has had me puzzled over several years. My altimeters often reported a sharp dip in altitude at ejection, indicating that the compartment with the altimeter was getting pressurized by the ejection charge. I figured it may have been due to too large vent holes in the payload section (altimeters need to sense the outside air to work properly, and vent holes are the easiest way to accomplish this). So I made my vent holes smaller, but the dip remained, showing up in flight after flight. I had resigned myself to living with it, but in his talk Bernard pointed out something that was so obvious I was kicking myself for not thinking of it.

Balsa is a very porous wood.

I use balsa couplers at the rear of my payload sections to connect them to the rest of the rocket, and so the ejection gases were flowing through the balsa into the compartment, spiking the pressure. The vent holes quickly allow the pressure to drop, but not before the altimeter records the spike as a sharp decrease in altitude. Simple, and you fix it by sealing the balsa - easiest way is to coat the coupler in wood glue. That will block the ejection gases. So I will soon start sealing the balsa couplers on my rocket payload sections, starting with the RX-16.

NARCONs are good - even old dogs like me learn a thing or two.

Friday, January 1, 2021

What to do when OpenRocket no longer works...

Some of you may know that I switched from Windows/PCs to MacOS/Macs several years ago - I got tired of all the issues with drivers, the "blue screens of death", the endless stream of updates, and the relentless virus/malware attacks. However, this change came with costs - the first being that Macs are very expensive compared to the equivalent PC in terms of horsepower. There is also less software available, especially in the engineering area, and you pretty much sell your soul to Apple. Microsoft only wants to own your computer's operating system - Apple takes the whole shooting match, hardware and OS. But I will say that things work very well the vast majority of the time - practically no system crashes, and the software that is available works smoothly and has a "better polish" than the Windows equivalent. I have had no problems with software from the Apple App Store; it's only the stuff one downloads that causes the fits.

Which brings me to OpenRocket...

On all my past Macs (including my MacBook Air laptop), OpenRocket has worked flawlessly; it even worked fine on my new Mac until yesterday, when I upgraded the operating system from Catalina (10.15) to Big Sur (11.1). I did the usual reinstall of Java you have to do when you perform such an upgrade, checked to make sure the Java was working, and then fired up OpenRocket as a test. That's when I saw this:

Well, crap.

I spent the next couple hours googling and trying things with permissions and stuff - nothing worked. My frustration mounted, and I began to understand the feelings of TARC newbies who struggle to get OpenRocket working on their computers. I had often shrugged off their issues by telling them their Java installs were not right, and that if Java was working, there would be no problems with OpenRocket. Well, darn it, my Java was working and the stupid program would not run! I can tell you, I will be much more sympathetic in the future.

For a few minutes, I thought OpenRocket's performances on the screen of my shiny new Mac were a thing of the past, and that I would have to run it on my laptop (which I am not going to upgrade to Big Sur anytime soon!). Then my searching revealed this page, in which someone had posted links to OpenRocket run times and executables compiled for different operating systems. I downloaded the MacOS version, and voila! OpenRocket once again graced the screen of my Mac!

Big sigh of relief.

However, this whole experience once again drove home the fact that major updates to our computer operating systems, driven by security and technology advances, are just as, if not more, frequent than software updates. This is especially true for hobby programs like OpenRocket, which hasn't been updated since 2015, and also for altimeter drivers/codes like those from PerfectFlite. Keeping these legacy codes running often involves hacks or bypassing OS security features, and eventually things reach a point where even that is not enough. Catalina did that to me, as 32 bit codes no longer work. Unlike Microsoft, which provided a fair amount of backwards compatibility, Apple simply forced developers to upgrade their programs to 64 bits. So now I have to find a Windows box to download data from my Perfectflite PNUT. This is the major reason I have largely switched to Bluetooth altimeters like the FlightSketch, as small vendors like PerfectFlite focus on the Windows platform, which is over 90% of the market. Macs are an afterthought, if there is a thought.

I understand that we can expect a new version of OpenRocket sometime in the foreseeable future, which would make me quite happy. It's a great program and needs to be maintained/upgraded.

Back to designing rockets...

Thursday, December 31, 2020

Bye Bye 2020!

Can't say I'll be sorry to see you gone... COVID-19 wreaked havoc on the world, causing many deaths, lost livelihoods, business failures, and radical changes in our daily lives. It also impacted the rocketry hobby, causing the cancellation of launches and a shift to online meetings. In addition to this plague, we had to deal with considerable bad weather - my goodness, the number of hurricanes! Hard to imagine a worse year.

Hoping 2021 turns out to be much better!

Saturday, November 28, 2020


I only made 2 flights at the November HARA launch; the first was that of the RX-16, described in the last post, and the second was the maiden flight of my Quest Q E-Z Payloader, a "Qwik Kit" I acquired many moons ago. It was recommended by Art Upton as a good starting rocket to loft his BoosterVision Mini GearCam, a 2.4 GHz camera that live-streamed the video to a receiver, much like the way it is done by NASA, Space X and ULA. While I tested the GearCam on the ground, I never got around to flying it - and for the life of me, I can't remember why. Anyway, the Q E-Z Payloader has sat on the shelf for over a decade, until I decided to launch it two weekends ago.

Quest Q E-Z Payloader (Click to enlarge).

And the rocket did carry a camera, even though it was not the one for which it was purchased. I taped the Estes camera to the side of the payload section, and, just to make things more nerdy, loaded a Perfectflite PNUT into the compartment. A quick weight check indicated that an Estes C6-5 would be about perfect for the flight - I estimated a peak altitude of around 350 feet, which was high enough to get good footage, but not so high as to make for a long walk. Yep, I had thought things through and prepared pretty well.

Uh huh...

The Q E-Z Payloader left the pad and headed up into the blue sky. I watched it arc over and was pleased to see the nylon Apogee chute deploy. But then I caught a glimpse of other pieces falling, and that's when it hit me...

I had forgotten to tape the nose cone to the payload tube, so it would stay in place throughout the flight.

So those two additional falling pieces were the nose cone (no big deal) and the PNUT altimeter (big deal, to the tune of $60). And I did not see where they landed, so I did not have a location to search.

Sighing, I trudged after the rocket, having little hope of recovering the nose cone or, more importantly, the altimeter (assuming it survived the fall). But fortune did smile upon me, for as I was returning to the flight line one of the rocketeers at the high power pads handed me the altimeter. He had heard it beeping - PNUTs are noisy little beasties - and located it on the ground using the sound. I also got back the nose cone, which was a minor miracle. The model has been put back on the shelf, ready for its next flight. And I hope to not be as stupid for that one.

Anyway, I downloaded the data from the altimeter - which appears to be undamaged, as it fell in its holder tube - and got an answer to the question "What does an altimeter record as it is free falling to the ground?" Apparently the tumbling results in oscillations, as you can see from the below graph. The altimeter was also not as snug in the holder tube as I would have liked, and that also shows in the flight profile. At least my motor choice was correct.

Q E-Z Payloader flight profile from November HARA launch (Click to enlarge).

Being taped to the side of the payload section, the camera stayed with the rocket, and I managed to pull a few interesting frames from the video:

Ignition (Click to enlarge)!

Coasting upward (Click to enlarge).

Parachute deploy (Click to enlarge).

Altimeter and nose cone falling away (Click to enlarge).

So a good ending came out of a royal screw-up on my part. That does not happen often.

Comparing instruments...

Today's electronics are wonderful; you can fit a lot of measurement capability into a very small package. There are a goodly number of choices available from various vendors and it is a very natural thing to compare capabilities and accuracy, especially when new products hit the market. That's one reason I built the clone of the Centuri RX-16 and the beefy Big Bertha look-a-like, Beulah. Their large payload sections and interchangeable motor mounts enable me to fly multiple instruments on the same flight, facilitating comparisons.

PocketLab Voyager

I was perusing the Estes website last month, and came across these teacher's bundles, which feature the large 24mm powered Green Eggs rocket and some electronics gizmo called the PocketLab. The prices were a little rich for my wallet, but I was intrigued by the PocketLab - I had not heard of it. A Google search instantly produced the manufacturer's website, where I learned that the PocketLab included in the Estes bundles was the PocketLab Voyager, a 1.5 x 1.5 x 0.6 inch mini laboratory capable of making measurements of the following:

  • Acceleration
  • Angular Velocity
  • Magnetic Field
  • Barometric Pressure
  • Altitude
  • Infrared Rangefinder
  • Internal Temperature
  • Temperature Probe
  • Humidity
  • Light Intensity
Wowzers! This is a lot of capability, and after perusing the online documentation, I figured I ought to get one - in the interest of science, of course. I never play... Anyway, the PocketLab Voyager arrived within a few days, and quick trial and error showed that it would fit - albeit very tightly - in the 1.6 inch diameter Estes BT-60 body tube (the Green Eggs rocket that Estes bundled with the Voyager is 1.8" in diameter). I was happy, as this meant I could use the RX-16 or Beulah to fly the PocketLab Voyager and compare it to other instruments.

So when I attended the HARA launch earlier this month, I carried with me my trusty RX-16, loaded with a Quest Q-Jet D16-4 and 3 devices in the payload section - the PocketLab Voyager, a FlightSketch Mini altimeter, and a Perfectflite PNUT altimeter (the TARC gold standard). I was curious not only to see the data returned by the instruments, but also to see how well my iPhone could configure and handle 2 Bluetooth devices simultaneously (Both the Voyager and the FlightSketch Mini communicate via Bluetooth). I need not have worried about the latter, as the phone was more than up to the task, and as for the former, the instruments agreed fairly well, as you can see from the below plot.

Comparison of altitude data taken on November 14 (Click to enlarge).

Note that the Voyager ceases to return data after 140 feet - that's my fault, as I had not yet figured out how to set the instrument to autonomously record data over a span of time (What? I have to read instructions?). So it was transmitting real-time numbers via Bluetooth, which stopped once the rocket passed beyond range. However, the little bit I received looked good. A club member pointed out that the FlightSketch data is systematically lower that of the PNUT, especially below 300 feet altitude. However, the difference is less than 5 feet, so while curious, I am not bothered by it.

The FlightSketch altimeter also is capable of measuring acceleration, so let's look at that data along with the Voyager's:

FlightSketch Mini and PocketLab Voyager acceleration data for the November 14 RX-16 flight
(Click to enlarge).

Again, the agreement is good until the Voyager data transmission stops. Kind of interesting to see 22 g's at ejection, which is substantially larger than the 12 g's experienced during thrusting.

A note about the PocketLab Voyager - the documentation is not that great, as they encourage you to "experiment" with the device to figure out how it works. However, their email support is awesome, answering questions about the device operation very quickly. They were able to help me to figure out why the iPhone app was not showing the screens that allow you to configure the PocketLab to collect data offline (iPhone has to be set to "light" not "dark" mode).

I did a reflight at last week's launch, but the bad luck pervading that afternoon messed things up. Structural repairs have been made to the RX-16 and it is awaiting a new coat of paint on the fin unit. I'll be trying again at the next launch - whenever that is.