High-Strength Composite Rocket Fins - Building Lumineer

hiiiiiii you know what's cooler than these fins? S A F E T Y: Epoxy is a sensitizer and your body's reaction gets worse every time you touch it, and fiberglass particles in your lungs will ruin your life :) You'll notice in nearly all of the build footage, I'm wearing gloves to protect my hands from touching the epoxy, a respirator with fresh cartridges to protect my lungs, often safety glasses to protect my eyes, and headphones to protect my ears, as a treat. If you're building something like this, please help your future self out, and wear PPE(Personal Protective Equipment). It's worth spending extra money on good protective equipment, as no amount of money will get that fiberglass dust back out of your lungs.

Want to know more about surface preparation? Here are some great places to look!

For more info:

[BPSspace]

Hey besties, Icarus Thiccarus back with another slammer of a video. Don't forget to peep that description to learn a little about why I'm wearing a respirator and gloves because getting hurt building rockets does n o t spark joy! Peace and love!

[RealEngineering]

Did someone say high strength composites?

[SeanHodgins]

I think you should put it on a taller, skinnier, and less stable table before testing the fin load next one. Just to be safe.

[AstroCharlie]

Joe, these are some of the best composite fins I've seen on any HPR. Thank you so much for taking the time to make this resource. Rocketeers everywhere will benefit from this for years to come.

[AirCommandRockets]

Pro Tip: Use a roller cutter for the fiberglass. You will never look back! Roller cutters are available for a few dollars at fabric stores.

[Orangie]

So, this was pretty impressive. When I saw you were doing layup and bonding I thought "Oh, Boy, this will be interesting!" As an aircraft tech and former bonding department manager at a composite aircraft company, it sounds like you've done your homework. I only cringed when I saw you sanding without gloves, but it looked like you learned how nasty that is by the end. Pro Tip: If you find your hands super itchy after sanding, try sticking masking tape to the area and pulling it off. Also, the amount of Hysol you were using poses very little threat of significant exotherm with the size of heater you were using.

[AirCommandRockets]

Epiglue is your friend for fillets. The epoxy doesn't sag under gravity so you can do all 4 fins at the same time. Saves lots of time.

[xylafoxlin]

Don't mind me sneaking into your shop to steal some of your talent

[claytonbuckley]

Hey Joe,
I have 10 years of experience working with composites and have been to multiple courses on the subject.

Just want to give you some tips.

The next time you do composite layups, consider placing your fabric between two pieces of heavy mil plastic that doesn’t stretch. Add your resin and squeeze out the extra. This keeps you from working air bubbles in the resin and creating “Resin Foam”.

On the outer most layer of the plastic you can have your shapes pre drawn out and ready for cutting or use an aluminum or some other material as a stencil. Use a sharp roller cutter to cut through your two layers of plastic and saturated fabric.

Next all you have to do is peel the bottom layer and stick the fabric in place. The top layer of plastic also helps keep the shape of the fabric from being distorted. Final peel that last layer off and you will find your edge quality to be much better and not have frayed edges.
Another tip is you can take the “plastic sandwiches saturated fabric”and place them in the fridge so they don’t cure as fast on you, this also makes removing the plastic easier.
Keep up the good work.

Also look into using micro-balloons/ microspheres for making your filets. It’s much lighter and is the same chemical make up of your resin.

[ianhennus]

epoxy tip: after mixing for about a minute, pour the epoxy in a new cup. This will help ensure there are no pockets of unmixed epoxy at the corners and surface of the cup. Keep up the good work, very inspiring!

[LewisRawlinson]

Hey Joe, great video. Just one thing I picked out, around 20:40 you said the process of applying resin to the cloth is called 'prepreg'. It's actually called "wetting out". Prepreg is a dry fibreglass or carbon fabric that has already been impregnated with resin and allowed to partially cure. The fabric is stored in a chiller to prevent it from fully curing and is then placed in an autoclave once laid up to fully cure the part. It's a completely different process to the "wet layup" which you are doing here.

[terpcj]

The difference between Joe and Xyla's approach to deadline rocket design is amazing...and oddly comforting in the similarities.

[dominicd]

"I am not a chemist" he says. Well you could be. Along with mechanical engineer, electrical engineer, software engineer, production manager, flight controller, physicist. Should I keep going? Great job man, keep up the good work and you'll get to the Karman Line in no time!

[theholymacintosh]

every garage composite engineer has definitely built a curing oven that they caution that NO ONE SHOULD EVER DUPLICATE

[USWaterRockets]

Hey Joe, 55 minutes on a 60 minute epoxy is cutting it really close. One thing you're doing that can cut into your work time is mixing the epoxy in a tall cup. The epoxy tends to self heat as it cooks off in a dense container and this reduces the work time. If you mix your epoxy in a shallow flat container (those disposable baking pans work great) it will not be able to concentrate heat and it will be workable a lot longer.

[snopyKS]

Classic office environment! Desk, keyboard, computer, flower pot, can of acetone

[LSUtiger]

I’m building a fiberglass Long-EZ in my garage. A few things I’ve learned:

Consider pre-pregging all 7 layups on the table before applying to the rocket. Allows more attention and dexterity to weave orientation and bubbles while still on a flat surface. Also, if you sandwich all layups between 2 sheets of wax paper (much cheaper than mylar) it allows you to cut the whole layup with scissors to a more exact and neat final shape. You can also draw on the top sheet of wax paper with a marker and a ruler with no mess. Just peel away the wax paper before applying.

I use EZ proxy from aircraft spruce.com. Longer cure time but ideal for lightweight aircraft.

If you can pinpoint the direction of the higher stress loads you can use lightweight unidirectional (UNI) cloth and strategically align the weave. My entire wings are done this way.

Consider mixing your 2 part epoxy with microballlons. Lots of strength, easily sandable and most importantly, lightweight. I use it all the time for fillets.

With 14-16 ply fins I think you can opt for much thinner and lightweight fin cores. Rigid, thin foam would work. Easily carved and shaped. Less mass, less drag, higher altitude.

Keep in mind I’ve never built a Mach 1 rocket, so take all this with a grain of salt. Just some thoughts. Nice work.

[ucrunmannedaerialsystems]

Thank you so much for making this video! We're a student organization at the University of California, Riverside and are planning to dive into using composites on our aircraft in the near future, so the timing of this is absolutely perfect!!

[mfryer]

A tip for trimming the cloth after its laid up. Before the epoxy is fully cured, but after it has started to stiffen up, it will be the consistency of chewing gum. You can cut it with a razor knife right up to the fin edge. This will save you tons of time sanding and will almost eliminate fiber glass dust.

A proven technique that we use on composite aircraft.

[BrianKelsay]

Excellent video. You not being a pro really helped make it sound less complex. You also went through the steps in a more clear fashion than I have seen before. It made it a lot more approachable than someone's cell phone video going through the process real quick.