What adhesive should I use? Part 1

Building bigger and bigger rockets requires stronger and stronger adhesives. Many of the glues I used in LPR arn't suitable for high power applications. Over the past few years ive gained experience of what adhesives should be used when and where. I believe that all adhesives have a place in rocketry, some should just be used for non-structural parts.  I wish I could send this blog post back in time to my past self so I would ruin my Cosmodrome Nike smoke with hot glue.

Let's start with epoxies.

"Low Quality" Epoxy
Low quality epoxy is the term I give to epoxies found at most hardware stores. Many of these are in disposable syringes or squeeze bottles. "Low-Quality" epoxies are mixed in a 1-1 ratio of resin to hardener. Fillers are added in the manufacturing process to achieve this 1-1 ratio. These added fillers decrease breaking strength and thicken the epoxy.
I have a set of BSI 8oz epoxies and use them quite often. The BSI epoxies come in 5minute, 15 minute, 30 minute and 20 minute (laminating). 5min is excellent for quickly "tacking" parts together or field repairs. 30minute works fine for fillets and has been my most used epoxy so far.
Even with the decreased strength these epoxies are perfect for almost any application. The bond well to almost any surface and are decently durable.
Epoxy like this is a must for any workshop.

Use for: Fiberglass, cardboard, Phenolic, Balsa, Most Plastics, and metals. 20min laminating epoxy is acceptable for small fiberglass layups.
DO Not use for: Parts requiring very high structural strength, very high heat applications.

"High Quality" Epoxy
"High Quality" Epoxy is more difficult to come by. You will not find it at most hardware stores and is usually ordered online. High quality epoxy is usually meant for fiberglass and carbon fiber layups. It is usually not mixed in a 1-1 ratio (with the exception of Aeropoxy). "HQ" Epoxy is typically sold by the quart or the gallon, rather then by the ounce. Most of these epoxies have a low viscosity and are ideal for soaking into parts. Many Higher-end epoxies are around 4 times stronger then the epoxy above (source.)
 These epoxies can often be thickened with an additive such as Phenolic Microballoons, Colloidal silica, or even carbon fiber. With these fillers the epoxy can be used to create smooth fillets.
Manufacturers include:
West Systems
Aeropoxy 
US Composites
and many more  

Use for: Everything
Do NOT use for: Applications that are under intense heat.

onto other adhesives....

Wood Glue
Surprisingly, wood glue is one of the strongest adhesives for wood-wood and wood-paper applications. Using wood glue on wood-wood joints is usually stronger then high quality epoxy. Wood glue works by soaking into the wood and hardening, this binds the wood together in a bond that will usually outlast the things being glued. I use wood glue for all of my engine mount assemblies and fin attachment. Wood glue shrinks as it dries so it should never be used for fillets. Woodglue should never be used on anything other then wood and paper. It will not bond to things like fiberglass, metal, or plastic. Besides that, it's great. You can work with it with your hands and washes off with a little water.

Use for: Wood, paper
Do NOT use for: plastic, fillets, fiberglass, metals,

Cyanoacrylates (CA) 

CA is also known as super glue. CA is a necessary adhesive to have around the shop. I use CA for tacking in all of my fiberglass or carbon fiber fins. CA dries very quickly, making it ideal for tacking in fins and joining parts that need to be bent. These joints should be reinforced later with wood glue or epoxy. CA comes in super thin, thin, normal, thick, super thick, gap filling, odorless and others. The main reason CA is not used more is the cost. CA costs 5x more then epoxy.

 Use For: Quick bonding, fiberglass, wood, metals, plastic.                                                                      Do NOT use for: structural joints 

 

JB Weld 

JB weld is a type of specialty epoxy adhesive. JB weld is intended to be used to "cold weld" metal structures togeather. Because of this, JB weld is very heat resistant and hardens like steel. In rocketry, JB weld is often useful for tacking in fins on minimum diameter rockets or securing motor retainers. JB weld is strong but it's loaded with fillers that decease strength and increase heat resistance. When deciding an adhesive for a strucural purpose that will NOT go under intense heat, it's best to go with a good epoxy instead. JB weld is also expensive, even expensive epoxies are much cheaper.

Use for: Retainers, Fin on Minimum diameter rockets

DO NOT use for: Things that epoxy could be used for. 

 

The shockwave 29

The Shockwave 29 is a high performance 29mm rocket. I wanted to gain experience building a rocket out of carbon fiber. I came up with a 1.26in wide, 24in tall mach buster. The body tube is 3 wraps of 2x2 twill carbon fiber. The fins are a homemade combination of 6oz fiberglass and 2x2 twill carbon fiber. They are attached with CA with carbon fiber fillets for strength and graphite-epoxy fillets for cosmetics and aerodynamics. The nose cone is a fiberglass 5-1 ogive from shockwave rocketry (hence the name).
She'll fly on a H410 Vmax at hellfire.
Estimated speed: Mach 1.31
Estimated altitude: 5400 feet.

 For more info: CLICK HERE