Fins

[rocketgirl2014]

Hello,

I'm a junior in high school taking an aerospace engineering class with a goal of constructing a mach speed rocket. One of the requirements that our teacher imposed was to construct our own rocket. I'm in the fin design team and I've been doing research, but I can't find good description on how to make G10 fins. Do you know how to construct G10 fins or any website that are helpful? Also, do you know the PSI of G10?

Sincerely,

Rocketgirl2014

 

[Racer1]

McMaster Carr is the place where I get mine.

https://www.mcmaster.com/#grade-g-10-garolite-plates/=ld2dzq

It comes in various thickness ans such. Not sure how big you're planning to make the rocket but that will affect fin thickness.

As for the 'PSI' im not exactly sure what you mean. but I have attached the materiel information sheet for G-10.

View attachment 8549KAC.pdf

Hope this helps!

 

[REK]

Hello,

I'm a junior in high school taking an aerospace engineering class with a goal of constructing a mach speed rocket. One of the requirements that our teacher imposed was to construct our own rocket. I'm in the fin design team and I've been doing research, but I can't find good description on how to make G10 fins. Do you know how to construct G10 fins or any website that are helpful? Also, do you know the PSI of G10?

Sincerely,

Rocketgirl2014

Quick question, is your class affiliated with Systems Go?

 

[rocketgirl2014]

Yes, my class is affiliated with System Go.

Quick question, is your class affiliated with Systems Go?

 

[REK]

Yes, my class is affiliated with System Go.

I used to be part of Systems Go. You shouldnt worry on G10 fiberglass breaking apart at Mach 1 speeds. My former High school usually got our G10 fins from Giant Leap Rocketry. Lots of sizes and and great prizes too. They also have that reflective plated G10 material. That stuff is awesome. Hope this helps .

 

[rocketgirl2014]

"PSI" stands for "pounds per square inch". I've heard that I need to take in account the PSI needed to create G10.

McMaster Carr is the place where I get mine.

https://www.mcmaster.com/#grade-g-10-garolite-plates/=ld2dzq

It comes in various thickness ans such. Not sure how big you're planning to make the rocket but that will affect fin thickness.

As for the 'PSI' im not exactly sure what you mean. but I have attached the materiel information sheet for G-10.

View attachment 116965

Hope this helps!

 

[REK]

"PSI" stands for "pounds per square inch". I've heard that I need to take in account the PSI needed to create G10.

That is of course you want to make your own G10 fins.

 

[rocketgirl2014]

My teacher told my class that we need to make our own G10 fins. It is extra credit if we find the instructions to make G10 by this friday. I need to get this extra credit to improve my grade.

 

[CarVac]

"PSI" stands for "pounds per square inch". I've heard that I need to take in account the PSI needed to create G10.

PSI needed to create G10 is separate from the PSI (or maybe KSI, kilo-pounds per square inch) ratings for elastic modulus and yield stress are separate.

It's pretty irrelevant what goes into the manufacturing, actually, and you can make (not actually G10) "g10" with no pressure at all, it just won't be quite as good.

EDIT: If you want to make your own, they won't be G10, because that's a fire resistance rating rather than something else. You can make a fiberglass-epoxy composite panel, which involves getting laminating epoxy (I recommend Aeropoxy 2320 resin plus 3660 hardener), wetting out a stack of fiberglass cloth, and squeezing it really hard between nonstick plastic sheets.

 

[REK]

My teacher told my class that we need to make our own G10 fins. It is extra credit if we find the instructions to make G10 by this friday. I need to get this extra credit to improve my grade.

Im no expert on this but I am positive I know what I am doing. First off do you have the cloth?

 

[rocketgirl2014]

We ordered the cloth this week.

 

[rocketgirl2014]

What do I need to do to create "G10" fins with no pressure?

PSI needed to create G10 is separate from the PSI (or maybe KSI, kilo-pounds per square inch) ratings for elastic modulus and yield stress are separate.

It's pretty irrelevant what goes into the manufacturing, actually, and you can make (not actually G10) "g10" with no pressure at all, it just won't be quite as good.

EDIT: If you want to make your own, they won't be G10, because that's a fire resistance rating rather than something else. You can make a fiberglass-epoxy composite panel, which involves getting laminating epoxy (I recommend Aeropoxy 2320 resin plus 3660 hardener), wetting out a stack of fiberglass cloth, and squeezing it really hard between nonstick plastic sheets.

 

[CarVac]

Do you have laminating epoxy?
Mixing cups and sticks?
Nitrile gloves?
Release film?
A room with good ventilation?
Two VERY FLAT, EXTREMELY STIFF plates of some material (whether it be ceramic tiles, blocks of steel, aluminum, granite, etc)?
Lots of clamps and/or weight to stack on top?
Paper towels to clean up?

 

[CarVac]

What do I need to do to create "G10" fins with no pressure?

To make fiberglass panel, you just wet out fiberglass cloth and stack it on top of itself. That's it.

What you gain from adding pressure is more fiber relative to resin, which increases strength and stiffness for a given cross-sectional area.

 

[REK]

Do you have laminating epoxy?
Mixing cups and sticks?
Nitrile gloves?
Release film?
A room with good ventilation?
Two VERY FLAT, EXTREMELY STIFF plates of some material (whether it be ceramic tiles, blocks of steel, aluminum, granite, etc)?
Lots of clamps and/or weight to stack on top?
Paper towels to clean up?

yeah you will need all this to make this work. Carvac pretty much is already reading my mind lol.

 

[REK]

If you have anything heavy it will benefit you. Find bricks or weights as for that will apply a lot of pressure. I have lots of cloth from my Mariah kits maybe I can give it a try with my 20 minute laminating epoxy and see how it turns out .

 

[REK]

Will try after I am out of class of course

 

[bobkrech]

Just a few questions.

What is the size of the rocket? Diameter and weight? What motors are you considering?

The materials you chose will have a lot to do with these numbers, but you should be aware that to build a rocket with a max V over Mach 1 does not require fiberglass. It can and has been done with aircraft grade plywood fins, a fiberboard airframe, and plastic nose cone.

A simple 4 ounce fiberboard 1.1" diameter rocket similar in design to the Wildman 24 will get you there with a CTI G145-15 24 mm motor.

Bob

 

[EeebeeE]

Bobkrech makes a valid point. Instead of a fiberglass tube, a 24mm Kraft phenolic body tube and a plastic nose cone should easily handle mach speeds because that small of diameter airframe is much more structually strong than an airframe made of the same materials in larger diameters. The reason why is that the walls of the airframe are roughly the same thickness until you get into 5+" diameter tube. Thus the smaller the diameter, the greater the proportionate thickness of the material. Phenolic or blue tube both could easily handle mach speeds.

Also since your fins on a 24mm rocket are going to be relatively small, plywood fins can work.

If your task is to make your own G-10, an easy way to do so is to lay a sheet of plywood down on a floor. Cover the plywood with 10 mil plastic (thick enough to withstand the heat reaction during the curing process). Lay out some epoxy on the sheet, cover with fiberglass. Add epoxy between each layer of glass and layer as many sheets of glass as desired. On your last layer, add epoxy to the top of the glass. Lay a sheet of plastic over that, followed by a sheet of plywood. Then stack about 5-cement blocks on top of everything. This will compress the fiberglass, evenly distribute your epoxy, and leave you with a pretty smooth surface on both sides of the fiberglass sheet you've made. Boatbuilders who need to make fiberglass sheets use roughly the same process and the bond is so strong you can use a similar process to bond sheets of plywood together end-to-end (it's called "scarfing").

To design and sim a rocket, go online and download "Open Rocket." It is free and can help you come up with a mach-busting design and simulated flights based on your design, construction materials, and engine choice. The only thing is it tends to be about 10-15% lighter in material weight estimates, so as you build, override the masses it calculates with actual weights.

 

[bobkrech]

Hello,

I'm a junior in high school taking an aerospace engineering class with a goal of constructing a mach speed rocket. One of the requirements that our teacher imposed was to construct our own rocket. I'm in the fin design team and I've been doing research, but I can't find good description on how to make G10 fins. Do you know how to construct G10 fins or any website that are helpful? Also, do you know the PSI of G10?

Sincerely,

Rocketgirl2014

To get back to your original question, G10 is a specification for a certain fiberglass manufacturing process. You can make your own fiberglass composite, but it won't be G10 since you don't have the manufacturing equipment nor the equipment to test it to make sure it meet the G10 specifications.

Most people would simply purchase a sheet of G10 fiberglass sheet and then cut it with a carbide blade band saw. You would use a shop vac to remove the fiberglass dust and you need to wear a dust mask or respirator to prevent you from inhaling the dust.

As previously stated you can get G10/FR4 (FR is fire resistant) sheet from McMaster-Carr. I've attached a catalog page with sheeting on it. For a 24 mm rocket you would use 1/16' thick sheet and table of composite properties. View attachment 3611.pdf View attachment 120711

Download the free RASAERO program as a simple design guide to assist in the design of effective low drag supersonic fins.
https://www.rasaero.com/

Bob

 

[mkadams001]

Bobkrech makes a valid point. Instead of a fiberglass tube, a 24mm Kraft phenolic body tube and a plastic nose cone should easily handle mach speeds because that small of diameter airframe is much more structually strong than an airframe made of the same materials in larger diameters. The reason why is that the walls of the airframe are roughly the same thickness until you get into 5+" diameter tube. Thus the smaller the diameter, the greater the proportionate thickness of the material. Phenolic or blue tube both could easily handle mach speeds.

Also since your fins on a 24mm rocket are going to be relatively small, plywood fins can work.

If your task is to make your own G-10, an easy way to do so is to lay a sheet of plywood down on a floor. Cover the plywood with 10 mil plastic (thick enough to withstand the heat reaction during the curing process). Lay out some epoxy on the sheet, cover with fiberglass. Add epoxy between each layer of glass and layer as many sheets of glass as desired. On your last layer, add epoxy to the top of the glass. Lay a sheet of plastic over that, followed by a sheet of plywood. Then stack about 5-cement blocks on top of everything. This will compress the fiberglass, evenly distribute your epoxy, and leave you with a pretty smooth surface on both sides of the fiberglass sheet you've made. Boatbuilders who need to make fiberglass sheets use roughly the same process and the bond is so strong you can use a similar process to bond sheets of plywood together end-to-end (it's called "scarfing").

To design and sim a rocket, go online and download "Open Rocket." It is free and can help you come up with a mach-busting design and simulated flights based on your design, construction materials, and engine choice. The only thing is it tends to be about 10-15% lighter in material weight estimates, so as you build, override the masses it calculates with actual weights.

The only thing I would change on this is to use 3/4" melamine instead of plywood. Then you can eliminate the plastic sheeting. I would wax the melamine with some release wax and do the layup as you described. I have done this method with great success and super easy.

 

[REK]

Did not have enough time to try the layup. By the time I got home, it was late at night.

 

[edwinshap1]

I've made my own fiberglass sheets multiple times, I actually have a piece on my desk. 5 layers of 5oz glass compressed together with a lot of clamps under moderate torque. They measure to 0.04" thick and are quite stiff when cut to size. I've surface mounted them to a rocket to hit about mach 1.2 without failure.

If you're looking for cheap in the long haul, there's nothing better than a gallon of the aeropoxy mix carvac linked above. It'll last you a long time and is great as far as strength and working time. I made a tube and fins for two rockets for under $10 per rocket, with an investment of epoxy. I doubt it's G10, but then again I'm not looking for G10, just a strong material I can make in my garage.

 

[REK]

Thank you for the tip on using 5 layers . I have a big 3K fiberglass sheet from the auto store that I bought for $6. I should try it on that. I wonder how aeropoxy would comepare to 20 minute laminating epoxy.

 

[new2hpr]

To really get the pressure up simply on the layup, build it up between your plates of waxed granite tile, etc. Then jack up the car, slip the sandwich under the tire, set it down gently, and wait. Make sure you've got plenty of paper towels around the edges to catch the squeeze-out, as there will be a lot.

Good luck on the project!
-Ken

 

[CarVac]

Thank you for the tip on using 5 layers . I have a big 3K fiberglass sheet from the auto store that I bought for $6. I should try it on that. I wonder how aeropoxy would comepare to 20 minute laminating epoxy.

Aeropoxy will give you 2-3x the working time, which is good if you want to squeeze out excess epoxy once the layup is finished.

I've never worked with the BSi laminating stuff, but if it's anything like the BSi adhesive epoxies, it'll smell TERRIBLE.

 

[edwinshap1]

I've never worked with the BSi laminating stuff, but if it's anything like the BSi adhesive epoxies, it'll smell TERRIBLE.

West Systems smells like peanut butter, so I like to use that on occasion when strength isn't that important

 

[CarVac]

West Systems smells like peanut butter, so I like to use that on occasion when strength isn't that important

Peanut butter? Really? Does adding phenolic microballons to it make it smell AND look the same?

Aeropoxy smells... faintly of yeast/baking bread. Kinda. Very difficult to describe.

 

[5x7]

It's your braincells imploding

 

[degreaser]

As far as PSI goes, the max pressure you can apply would be 14.7 using a vacuum pump...
If you want to apply more than atmospheric pressure, you would need other methods like an autoclave.

Note that is 14.7 lbs per square inch. So if your fin was say 6" x 3", vacuum bagging would produce the equivalent of placing a 264.6lb weight on top of the laminate stack.