TheNewGuy
Well-Known Member
- Joined
- Apr 24, 2017
- Messages
- 48
- Reaction score
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Hello Everyone,
I want to thank all the people who replied to my last thread sometime ago. I really appreciate everyone offering advice, I like to learn as much as I can.
Before I start, I just want to apologize for the wall of text. I have ran out of people to talk about rockets too, even my family is tired of me blabbing about it. :eyeroll: So I hope you guys don't mind me blabbing here.
My first build was a LOC Hi-Tech, which I learned a lot from building and flying. I never posted pictures of it because it's way too embarrassing some of the obvious mistakes I made. I used an enormous amount of epoxy on the fillets for the fins, for example, not realizing that just because you add more doesn't mean the fins are more likely to stay on.
I also put fiberglass on the airframe of the rocket because I wanted to do a Level-2 certification on it (which was successful!). I learned from some of the experienced guys at my local launch that, aside from the fact that I used too much fiberglass resin, I didn't need to fiberglass the airfame at all. I was advised that the cardboard airframe would have been able to withstand the power of the J270 that I got my L2 on.
Another thing I learned, although not flight critical, is that I should have spent more time on paint. I just rattle canned orange paint on the rocket, after watching John Coker's YouTube video on simple painting I learned that preparation, even when doing simple rattle can paints, is very important.
Taking all various lessons learned on my first build, I decided I was ready to take a shot at a second one. Before I started on my second build, I thought I'd throw in a cool motor into the Hi-Tech and see what would happen. I launched it with an Aerotech J425, and it flew really well. When I recovered the rocket, the only damage was a fillet that had separated from the cardboard (I only put fiberglass on the body and not the fins). Despite the failure of the epoxy fillets, the fin was still dangling in the slot of the airframe!
After that flight, I started to look for ideas on what I wanted to do for my next rocket. I decided that I had three main goals:
I did some research with these goals in mind and I started to become fascinated with the idea of a minimum diameter rocket.
After reading a thread about how people overbuild their rockets I started to lean more and more towards using cardboard instead of fiberglass for the airframe. The advantages of using cardboard vs fiberglass or even carbon fiber is that it's cheap and very light weight.
Someone posted here on TRF that you could convert any rocket kit to minimum diameter just by setting aside the motor mount and grinding down the tabs on the fins to be only the thickness of the airframe. This way the fins will fit into the slot, but don't go past the slot blocking your motor.
I ended up going with a 38mm "Mini Tomach" from Madcow Rocketry and today I finished sanding and grinding down the fins. I test fitted everything, and so far it's looking good!
I just need to decide how I want to fillet the fins. I'd like to try not to "overbuild" my rocket while at the same time being able to reach both my altitude and speed goals (if possible).
How should I approach the fins so that they can withstand high speeds? From research on this forum and conversations I've had, these are some options I have found:
Another thing I want to add is that I don't plan on immediately jumping into flying J's with this rocket. My plan is to start with the modest H123, then make my way up to big J's. I'd like to compare the performance of this rocket vs my old Hi-Tech.
Your input and advice is highly appreciated!
I want to thank all the people who replied to my last thread sometime ago. I really appreciate everyone offering advice, I like to learn as much as I can.
Before I start, I just want to apologize for the wall of text. I have ran out of people to talk about rockets too, even my family is tired of me blabbing about it. :eyeroll: So I hope you guys don't mind me blabbing here.
My first build was a LOC Hi-Tech, which I learned a lot from building and flying. I never posted pictures of it because it's way too embarrassing some of the obvious mistakes I made. I used an enormous amount of epoxy on the fillets for the fins, for example, not realizing that just because you add more doesn't mean the fins are more likely to stay on.
I also put fiberglass on the airframe of the rocket because I wanted to do a Level-2 certification on it (which was successful!). I learned from some of the experienced guys at my local launch that, aside from the fact that I used too much fiberglass resin, I didn't need to fiberglass the airfame at all. I was advised that the cardboard airframe would have been able to withstand the power of the J270 that I got my L2 on.
Another thing I learned, although not flight critical, is that I should have spent more time on paint. I just rattle canned orange paint on the rocket, after watching John Coker's YouTube video on simple painting I learned that preparation, even when doing simple rattle can paints, is very important.
Taking all various lessons learned on my first build, I decided I was ready to take a shot at a second one. Before I started on my second build, I thought I'd throw in a cool motor into the Hi-Tech and see what would happen. I launched it with an Aerotech J425, and it flew really well. When I recovered the rocket, the only damage was a fillet that had separated from the cardboard (I only put fiberglass on the body and not the fins). Despite the failure of the epoxy fillets, the fin was still dangling in the slot of the airframe!
After that flight, I started to look for ideas on what I wanted to do for my next rocket. I decided that I had three main goals:
- High Altitude
- First 1 mile
- Next 2 miles
- Lastly 3 miles
- Sophisticated Electronics - I graduated last year in EE, and I am itching to do something cool with the electronics. I have TONS of ideas.
- Flight Computer
- Payload Electronics
- Etc
- Speed
- I would like to break mach, but goals 1 & 2 take priority
I did some research with these goals in mind and I started to become fascinated with the idea of a minimum diameter rocket.
After reading a thread about how people overbuild their rockets I started to lean more and more towards using cardboard instead of fiberglass for the airframe. The advantages of using cardboard vs fiberglass or even carbon fiber is that it's cheap and very light weight.
Someone posted here on TRF that you could convert any rocket kit to minimum diameter just by setting aside the motor mount and grinding down the tabs on the fins to be only the thickness of the airframe. This way the fins will fit into the slot, but don't go past the slot blocking your motor.
I ended up going with a 38mm "Mini Tomach" from Madcow Rocketry and today I finished sanding and grinding down the fins. I test fitted everything, and so far it's looking good!
I just need to decide how I want to fillet the fins. I'd like to try not to "overbuild" my rocket while at the same time being able to reach both my altitude and speed goals (if possible).
How should I approach the fins so that they can withstand high speeds? From research on this forum and conversations I've had, these are some options I have found:
- Wood glue (I don't think this would withstand mach?)
- Aeropoxy ES6209
- RocketPoxy
- 15 minute epoxy (vs 5 minute epoxy?)
- Using any of above then fiberglassing the fins tip to tip (is this neccessary?)
Another thing I want to add is that I don't plan on immediately jumping into flying J's with this rocket. My plan is to start with the modest H123, then make my way up to big J's. I'd like to compare the performance of this rocket vs my old Hi-Tech.
Your input and advice is highly appreciated!
). The thin laminating epoxies (like West) are my daily driver. Proven products, can be used as a general purpose adhesive, good for injecting and laminating, and can be thickened for external fillets. JB Weld is a high-temp product that is very sticky, which makes it great for buttering fin roots on both surface mount and TWT projects. And Proline 4500 has some interesting properties that make it great for external fillets, plus it's also a high temp product. I have some Rocketpoxy on order and will get to play with in on my next build.
