Geezer TARC 2021

The TARC Geezers ready their rockets (Photo by Patrick Morrison- Click to enlarge).

I'm back.

Maybe... The pandemic has dragged on and on, and my motivation really began to suffer several months ago. Things are still sucky out there in the world, but my guilt over neglecting the blog has now got the edge over my depleted morale. So I'm going to try to restart blog posts. We shall begin with a summary of this year's Geezer TARC competition.

As you may know, this year's TARC challenge was to fly two eggs "lying on their back" to 835 feet and bring them safely back to the ground in 41- 44 seconds. The two eggs were going to mean a fairly heavy rocket, but them being mounted horizontally was also going to require at least a 2.5 inch tube for the payload section, thereby adding more surface area/drag. "Gonna need F impulse" I thought as I started designing.

I should have listened to my instincts. But we'll come to that in a minute.

I didn't take very long for me to design EggTu - the fairly conventional rocket used a 29 mm, BT-60 sustainer with upscale Alpha fins joined to a BT-80 payload section housing the eggs, Apogee egg cushions and a Firefly altimeter. The sims showed plenty of margin, even suggesting it could make 835 feet on an E30. I was little bit skeptical, so I ported the design over to Rocksim - it gave similar results with a standard drag coefficient of 0.75. My doubts laid to rest, I moved on to building the rocket, installing the 29 mm motor mount "just in case" (very easy to adapt down to 24 mm motors).

Annotated EggTu design (Click to enlarge).

Weather and other things got in the way of the normal September launch, so the Geezer TARC flights had to wait until the October HARA launch in Woodville. The night before, I was once again nervous about using an E30 motor; the rocket seemed too heavy for an E to power it over 800 feet. So I entered EggTu's mass and diameter into my iPhone's rocket app, which spit out 700 feet on an E30. Great... I then went to thrustcurve.org and used that site's altitude calculator. It too gave a peak altitude around 700 feet for an E30 motor. I was in a fix - the two sophisticated sims said 840 feet and the two simple ones indicated 700. What to do?

October 9 was beautiful day for flying in Woodville, with comfortable temps and blue skies. There were four of us competing in Geezer TARC - myself, Duane, Vince and Doug. Doug was a first timer, eager to try his hand against the "veterans" (if there is such a thing in Geezer TARC). Vince's rocket was the usual Frankenstein, featuring an Estes Omega sustainer and a BT-80 payload section. The BT-60/BT-80 adapter was fashioned out of styrofoam, and it looked weak - very weak. My comment to him - which proved to be prophetic - was that I didn't think it would take the flight stresses.

Vince proudly displays his ill-fated Geezer TARC rocket
(Photo by Patrick Morrison - Click to enlarge)

You can guess what happened - Vince's rocket made it to about 160 feet before the adapter broke and the rocket fell out of the sky. Max altitude of 158 feet and a duration of 9.38 seconds, giving him an 803 score. Miraculously, the eggs survived.

Duane's design was the opposite of mine - his rocket featured a 3" diameter sustainer adapted down to a BT-80 payload section. Powered by the Mayer TARC standard F32 motor, it was very robustly built. To be honest, I considered it the better design - not only were the fins shaped to minimize breakage, but the larger diameter sustainer meant he could use standard rail buttons instead of the bulky 3D printed rail guides I had to purchase from Apogee. Elegantly simple.

Duane's Geezer TARC rocket awaits launch (Photo by Patrick Morrison - Click to enlarge).

And it performed fabulously. Duane's rocket soared to 840 feet, only 5 feet above the goal, and was down in 41.76 seconds. A 5 score - hard to beat, even at the TARC Finals.

Doug's rocket raised some eyebrows - not only were the fins very, very small, but he also used a Pringles can as the payload tube. It left the pad and almost immediately flew nearly horizontal, reaching a peak altitude of of 177 feet. The parachute deployed and he managed to get 24.36 seconds duration before the Pringles can touched ground. Score - 724. Now that he has some experience, I'm sure Doug is going to be a contender in future years. At least he now knows not to put too much faith in Open Rocket.

Doug's Geezer TARC rocket begins to arc over
(Photo by Patrick Morrison - Click to enlarge)

A lesson I have yet to learn, as I decided to go with the E30 in my flight. EggTu flew straight as an arrow, but only reached a max altitude of 678 feet. Naturally, the duration was also short, only 38.56 seconds. This resulted in a miserable 2nd place score of 167.

EggTu descends on its two 15 inch parachutes (Photo by Patrick Morrison - Click to enlarge).

It was over. Duane had won Geezer TARC for the third time.

And he deserved it - his design was clearly superior to any of the others, including mine.

Vince got the Flying Pig award for the worst flight. Doug's rocket may have had small fins, but at least it did not come apart.

Just to check things out a bit more, I reflew EggTu a month later at Pegasus field, this time with an F20. It reached 801 feet and was down in 41 seconds - a 34 score. Not good enough to beat Duane, but a damn sight better than its performance on the E30.

Moral of this tale - Trust your instincts!

Duane the winner! (Click to enlarge)

Vince with the "Flying Pig" (Click to enlarge).