Well, I had a build pile before, but for the first time I can remember I also have a building pile.
Okay, a little backstory:
My local low-power club, DART, hosts a number of ARC (formerly TARC) teams and a number have advanced to finals. San Diego is well-represented in competition. But why should high-schoolers have all the fun?
Thus, DART created the “Geezer TARC” event, an unofficial precision egg lofting event for all ages and affiliations but with different design requirements so that TARC teams are generally unable to use the data and must gather their own. I think the target altitude is different, and entries can come from any source. There are no body tube requirements like there are for TARC teams this year.
Full rules here:
https://www.nar.org/site/section317/geezer-tarc/
On DART’s Facebook page, I described the concept for my entry:
“Currently I’m looking at converting a Quest/AeroTech Courier with a 29mm mount, single-piece recovery, 1010 rail buttons, and an extended body tube with payload bay to meet the contest requirements. A modest E motor should hit the altitude target. Single-motor operation makes the E35W Q-Jet more viable.
(snip)
“Currently I’m only looking to qualify and score, not to beat Chris [Flanigan, DART Director] and any other competitors that may show.”
Now, the Courier is a classic egg lofter, but these are not necessarily simple conversions, especially not with the kind of time I have and the rapidly approaching 11/11 deadline. I’m hoping to have the guts all sorted out and the thing ready for a test flight by Saturday. You can bet there will be a few manic episodes dumped into the work on this rocket!
Here’s the first update I posted:
“G-TARC update: After half-a-dozen shopping excursions, three or four engineering challenges solved, and a few experimental subassemblies put together and validated on a preliminary basis, I feel confident and ready to begin assembly.
“First though: A weigh-in. I don’t expect this figure (253g) to stay static but I did need to know what kind of headroom I’d be looking at. A minimum length (650mm) and maximum mass (650g) makes you really think about the limits and discourages you from trying anything extreme.
“In this case I need not have worried. The preliminary figure is encouraging. I have more than enough length and I’m not even close to the mass limit.
“For added context: The motor mount is glued in place, probably dried and curing by now. The forward centering ring is just a masking tape shim held in place by wood glue, the rear centering ring is the stock one, cored out *not quite enough* and butting up against the end of the body tube instead of slipping inside. That joint got CA superglue. A preliminary breath test indicates a good gas seal but I will likely apply some more glue later to act as a sealant. The aftmost portion will be cut down a bit to accommodate an Estes 29mm retainer.
“The brown-colored tube is a BT-55 and that will be the extension, and I’ve stuffed both of the stock Quest polyethylene sheets for chute assembly inside, plus a length of Estes elastic shock cord (the Pro Series II stretchy fabric kind also found in some AeroTech kits). The Quest T35 will be cut in two for the BT-55 to serve as middle component/payload bay. The nose will slip into the forward segment of the T-35. I’ll still need to fashion a bulkhead and shock cord attachment point of some sort but I don’t expect that to eat up all my room for weight gain.
“The rail standoff has been beefed up a bit, constructed out of a bit 1/4-inch birch ply cut to similar dimensions, and another 1/4-inch plate held on with wood glue, which will hold the rail buttons. In addition to the attachment screws I have some pretty serious JB Weld in my supply, which will be applied liberally on all remaining joints in that assembly and I may make some fillets on the existing glue joint as well.
“The fins will probably stay stock balsa unless a test flight reveals that they break, in which case they’ll be replaced. I probably won’t fly the Quest chutes, more likely I’ll get a stronger, more compact nylon one from the Discount Rocketry trailer or use one I happen to scrounge up from my own supply.
“A few more grams of dog barf, glue, and one or two minor structural components will give me a final weight. Part of me wonders if I can get away with flying this on less-thrusty motor like an F23.
“Either way, my only goals are to qualify and score. I’ve seen how hard TARC can be and I have no illusions as to my skills as a builder!”
That mass figure includes a Jumbo-sized egg in the nose, by the way. If you look closely you might be able to see the bit of condensation that formed since I had just taken it out of the refrigerator.
One thing I’m realizing from this build is that I don’t really like the Gorilla brand of wood glue, at least not until it has sat for about 10 minutes and become somewhat more tacky. I refuse to turn this into a glue thread, but you can rest assured that I will be trying something else soon!
@fyrwrxz was kind enough to recommend that I get into contact with Discount Rocketry for custom laser-cut centering rings, which appear to just not exist commercially for this combination of diameters. I’m reasonably happy with my solution though, so I might have a spare set lying around at some point, maybe for some improvements to this project.
Okay, a little backstory:
My local low-power club, DART, hosts a number of ARC (formerly TARC) teams and a number have advanced to finals. San Diego is well-represented in competition. But why should high-schoolers have all the fun?
Thus, DART created the “Geezer TARC” event, an unofficial precision egg lofting event for all ages and affiliations but with different design requirements so that TARC teams are generally unable to use the data and must gather their own. I think the target altitude is different, and entries can come from any source. There are no body tube requirements like there are for TARC teams this year.
Full rules here:
https://www.nar.org/site/section317/geezer-tarc/
On DART’s Facebook page, I described the concept for my entry:
“Currently I’m looking at converting a Quest/AeroTech Courier with a 29mm mount, single-piece recovery, 1010 rail buttons, and an extended body tube with payload bay to meet the contest requirements. A modest E motor should hit the altitude target. Single-motor operation makes the E35W Q-Jet more viable.
(snip)
“Currently I’m only looking to qualify and score, not to beat Chris [Flanigan, DART Director] and any other competitors that may show.”
Now, the Courier is a classic egg lofter, but these are not necessarily simple conversions, especially not with the kind of time I have and the rapidly approaching 11/11 deadline. I’m hoping to have the guts all sorted out and the thing ready for a test flight by Saturday. You can bet there will be a few manic episodes dumped into the work on this rocket!
Here’s the first update I posted:
“G-TARC update: After half-a-dozen shopping excursions, three or four engineering challenges solved, and a few experimental subassemblies put together and validated on a preliminary basis, I feel confident and ready to begin assembly.
“First though: A weigh-in. I don’t expect this figure (253g) to stay static but I did need to know what kind of headroom I’d be looking at. A minimum length (650mm) and maximum mass (650g) makes you really think about the limits and discourages you from trying anything extreme.
“In this case I need not have worried. The preliminary figure is encouraging. I have more than enough length and I’m not even close to the mass limit.
“For added context: The motor mount is glued in place, probably dried and curing by now. The forward centering ring is just a masking tape shim held in place by wood glue, the rear centering ring is the stock one, cored out *not quite enough* and butting up against the end of the body tube instead of slipping inside. That joint got CA superglue. A preliminary breath test indicates a good gas seal but I will likely apply some more glue later to act as a sealant. The aftmost portion will be cut down a bit to accommodate an Estes 29mm retainer.
“The brown-colored tube is a BT-55 and that will be the extension, and I’ve stuffed both of the stock Quest polyethylene sheets for chute assembly inside, plus a length of Estes elastic shock cord (the Pro Series II stretchy fabric kind also found in some AeroTech kits). The Quest T35 will be cut in two for the BT-55 to serve as middle component/payload bay. The nose will slip into the forward segment of the T-35. I’ll still need to fashion a bulkhead and shock cord attachment point of some sort but I don’t expect that to eat up all my room for weight gain.
“The rail standoff has been beefed up a bit, constructed out of a bit 1/4-inch birch ply cut to similar dimensions, and another 1/4-inch plate held on with wood glue, which will hold the rail buttons. In addition to the attachment screws I have some pretty serious JB Weld in my supply, which will be applied liberally on all remaining joints in that assembly and I may make some fillets on the existing glue joint as well.
“The fins will probably stay stock balsa unless a test flight reveals that they break, in which case they’ll be replaced. I probably won’t fly the Quest chutes, more likely I’ll get a stronger, more compact nylon one from the Discount Rocketry trailer or use one I happen to scrounge up from my own supply.
“A few more grams of dog barf, glue, and one or two minor structural components will give me a final weight. Part of me wonders if I can get away with flying this on less-thrusty motor like an F23.
“Either way, my only goals are to qualify and score. I’ve seen how hard TARC can be and I have no illusions as to my skills as a builder!”
That mass figure includes a Jumbo-sized egg in the nose, by the way. If you look closely you might be able to see the bit of condensation that formed since I had just taken it out of the refrigerator.
One thing I’m realizing from this build is that I don’t really like the Gorilla brand of wood glue, at least not until it has sat for about 10 minutes and become somewhat more tacky. I refuse to turn this into a glue thread, but you can rest assured that I will be trying something else soon!
@fyrwrxz was kind enough to recommend that I get into contact with Discount Rocketry for custom laser-cut centering rings, which appear to just not exist commercially for this combination of diameters. I’m reasonably happy with my solution though, so I might have a spare set lying around at some point, maybe for some improvements to this project.
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