First HPR scratch build, Tank Girl

I started my first HPR scratch build today, that I'm calling "Tank Girl". (Thanks to El Cheapo for the name suggestion.) Tank Girl will be 4" diameter transitioning to 3", and either 82" or 92" long (depending on whether I decide to use the payload section or not). I started by cutting out the centering rings, from 1/4" plywood. I don't have a hole saw big enough, so I cut them out on the bandsaw, then drilled 1/4" holes through the centers. I mounted them on the lathe and cut them to final size, using a 4" payload section to check the size.

Using a 1-9/16" hole saw, I cut the center holes in the centering rings. I'll sand them to final size with my Dremel, once I get the 38mm motor tube in hand.

I wanted to use thicker than 1/8" plywood for the fins. I have some 5.2mm (0.20"), but decided it was a little too thick. So I bought some 5/32" Finnish birch plywood from Woodcraft. Nice stuff, but expensive at $20 for a 24" x 30" piece. I decided to try something new for me, and I cut out the fins with my tablesaw. I pinned the fins with 1/4" dowel pins to hold them together when I made the cuts. Using both a taper jig and the miter, I got them all cut out except for the tabs.

Using the bandsaw, I got all the tabs cut out. There will be six fins and three finlets, and being able to do most of the cutting with them in stacks really saved some time. I sanded them on the stationary belt sander, and they're ready to go. Now if only FedEx would bring the package from LOC-Precision...

Saw the tank girl on thrust curve. You put it there?

Aksrockets said:

Saw the tank girl on thrust curve. You put it there?

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Yes sir. It's not accurate, though, I just guessed at the weight.

I decided to try something new for me. I epoxied pieces of plywood to the centering rings where I'll be screwing in the rail buttons. Hopefully they'll be easier to drill into and be stronger.

Got the tee-nuts installed and epoxied in the lower centering ring.

I've done the same thing on some of my centerings. On others I covered the epoxy with JB weld just because I wanted to try it out. Someone here posted pictures of their build and they used it to secure the t-nuts. Seemed like a good idea.

My question is why are you only using a 38mm spout? It would be nice to see such a big rocket boosting on a 54mm reload and you've got your Adept22...

Looking good so far Jim. Cant wait to see more. Wow, I wish I had your tools!

o1d_dude said:

I've done the same thing on some of my centerings. On others I covered the epoxy with JB weld just because I wanted to try it out. Someone here posted pictures of their build and they used it to secure the t-nuts. Seemed like a good idea.

My question is why are you only using a 38mm spout? It would be nice to see such a big rocket boosting on a 54mm reload and you've got your Adept22...

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I can go up to J reloads with my 38/720 case. Didn't seem reasonable to have to buy 54mm hardware. Besides, you know me. Low N Slow! LOL

qquake2k said:

I decided to try something new for me. I epoxied pieces of plywood to the centering rings where I'll be screwing in the rail buttons. Hopefully they'll be easier to drill into and be stronger.

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I've been doing this for all of my builds too. I do use regular wood glue to attach the blocks though. It's just as strong, or maybe stronger then using epoxy.

Handeman said:

I've been doing this for all of my builds too. I do use regular wood glue to attach the blocks though. It's just as strong, or maybe stronger then using epoxy.

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I use epoxy because it sets so much faster.

I usually put half moon baffles in the motor tubes of my build, and Tank Girl is no exception. This time I cut them out with a hole saw, epoxied the pilot hole shut, and cut them in two with the bandsaw. I decided to put three of them in this time. I also drilled the holes in the forward centering ring for the u-bolt.

I cut the motor tube with the miter saw. I wrapped tape around it hoping it would keep the edges cleaner, but it didn't seem to help. So I flooded the end with CA so I could sand it smooth.

:cyclops:

Where do you guys get these weird sized hole saws? In my neck of the woods if it ain't 2 inch 3 inch maybe 1 and a half you can't find it!

Andrew

accooper said:

Where do you guys get these weird sized hole saws? In my neck of the woods if it ain't 2 inch 3 inch maybe 1 and a half you can't find it!

Andrew

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They sell a lot of in between sizes at OSH, Sears, Home Depot, and Lowes. Usually by 1/16ths. Home Depot even had a 4-1/8" hole saw that I considered buying for the centering rings. But I couldn't justify spending $22 for something I'd use so infrequently. I did recently buy a 15/16" hole saw from OSH, that I use for 24mm motor mount centering rings.

Got the forward centering ring epoxied on the motor tube.

Got the baffle plates epoxied in.

qquake2k said:

I use epoxy because it sets so much faster.

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Maybe that's why it takes me so long to finish a build. I had one that took 22 months.

qquake2k said:

I cut the motor tube with the miter saw. I wrapped tape around it hoping it would keep the edges cleaner, but it didn't seem to help. So I flooded the end with CA so I could sand it smooth.

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What kind of blade do you have. I found that if I went to a fine tooth finishing blade in my table saw, I could cut a lot of things without splinters, like tubes and fins, where the standard blade would chew things up.

Handeman said:

What kind of blade do you have. I found that if I went to a fine tooth finishing blade in my table saw, I could cut a lot of things without splinters, like tubes and fins, where the standard blade would chew things up.

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I think it's the blade the saw came with, which is probably the problem. It's a 12", and I do have a new blade for it, I just need to change it.

I have a 60 tooth carbide blade for all my tube slicing. Works great for making baloney sliced tube fins like on my Steppin Razor.

Of course attaching them in proper alignment to the air frame is where the fun begins.

o1d_dude said:

I have a 60 tooth carbide blade for all my tube slicing. Works great for making baloney sliced tube fins like on my Steppin Razor.

Of course attaching them in proper alignment to the air frame is where the fun begins.

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Yeah, I need to change the blade in mine. I've cut aluminum and all kinds of hardwood with that poor blade.

Looking good so far. The construction will not fall short of the name, that's for sure. FWIW, take a second before you fit that mmt to the body tube. Think about saving it for a bird that isn't so big. You can always adapt down, but never up when it comes to motor choice.

El Cheapo said:

Looking good so far. The construction will not fall short of the name, that's for sure. FWIW, take a second before you fit that mmt to the body tube. Think about saving it for a bird that isn't so big. You can always adapt down, but never up when it comes to motor choice.

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With the 38mm hardware I already have, I can fly up to a J500, and I'm not even Level 2. I don't think Tank Girl will be all that heavy. I recently flew my Hyperloc 835, which is 5 lbs without motor, an an I218 and it still drifted a half mile away. With my 38/720 case, I can fly up to an I600, which would be more than enough for me. In fact, I plan on flying the Hyperloc on the I600 for my first dual deploy flight. If I wanted to go to 54mm motors, I'd have to buy all new hardware.

I'm sure, with your rock solid motor retention, there is more than one or two club members that would loan you a case.

El Cheapo said:

I'm sure, with your rock solid motor retention, there is more than one or two club members that would loan you a case.

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Oh I'm sure, but it's not necessary. My 5 lb Hyperloc sims to 1500 ft on an I245 and 2600 ft on an I600, and Tank Girl will be lighter than that. 38mm motors will be plenty for me. The sites I fly at are huge, but one has a lot of rolling hills, so recovery can be difficult. I'm more than content keeping my rockets under 1500 ft. Remember, when I became a BAR i had absolutely no intention nor desire of ever getting my Level 1. I don't currently have any plans of getting my Level 2, but I know that can change. But for now, I'm happy exploring the benefits of Level 1.

Perhaps once you get the dual deploy worked out you will change your mind.

54mm and s 38mm adapter for now.