New to HPR Fiberglassing Fins

[JoeFilgas]

Hi, so I’ve been searching the threads for quite awhile and can’t find exactly what I’m looking for. I want to build my LOC V2 to eventually get a Level 1. I haven’t yet built anything with plywood fins. These are only 3 ply fins and are 1/8” in thickness. This V2 is heavy and I want to protect the fins from a hard landing mostly. My question is should I glass them before installation or after. I’ll be using West Systems epoxy resins and fillers. If glassing before do I leave the tab untouched? Wondering how the external epoxy fillets work in The sequence. Any help would be greatly appreciated. I know how to fiberglass I’m just wondering more about procedure. Thanks for any help!

 

[rharshberger]

View attachment 610196Hi, so I’ve been searching the threads for quite awhile and can’t find exactly what I’m looking for. I want to build my LOC V2 to eventually get a Level 1. I haven’t yet built anything with plywood fins. These are only 3 ply fins and are 1/8” in thickness. This V2 is heavy and I want to protect the fins from a hard landing mostly. My question is should I glass them before installation or after. I’ll be using West Systems epoxy resins and fillers. If glassing before do I leave the tab untouched? Wondering how the external epoxy fillets work in The sequence. Any help would be greatly appreciated. I know how to fiberglass I’m just wondering more about procedure. Thanks for any help!

anything you dont want to glass you can cover with masking tape and while the resin is still "green" cut away the glass and resin over the tape and peel everything off.

 

[bad_idea]

For through-the-wall wood fins, I glass the fins in advance nowadays, including the tab. For a kit that means you'd need to widen the slots in the body tube slightly. I'm sure though this is a question that will get as many different answers as there are rocketeers to answer it.

 

[JohnCoker]

Yes, 1/8" fins are pretty thin. I would laminate them before building the rocket. (It's much easier to do when they're flat and the result will be stronger.)

 

[JoeFilgas]

For through-the-wall wood fins, I glass the fins in advance nowadays, including the tab. For a kit that means you'd need to widen the slots in the body tube slightly. I'm sure though this is a question that will get as many different answers as there are rocketeers to answer it.

Thank you! I was kind of leaning that way and was hoping for confirmation!

 

[JoeFilgas]

Yes, 1/8" fins are pretty thin. I would laminate them before building the rocket. (It's much easier to do when they're flat and the result will be stronger.)

Thanks!

 

[JoeFilgas]

anything you dont want to glass you can cover with masking tape and while the resin is still "green" cut away the glass and resin over the tape and peel everything off.

Thank you!

 

[Aeva]

For through-the-wall wood fins, I glass the fins in advance nowadays, including the tab. For a kit that means you'd need to widen the slots in the body tube slightly. I'm sure though this is a question that will get as many different answers as there are rocketeers to answer it.

For through the wall, preglassed fins, do you also glass the fillet area/put fiberglass connecting your fins to the body? or do you just do fillets? I did the latter for my first HPR... haven't gotten to launch it because of some delays, but I cannot imagine them coming out or breaking unless something goes wrong. I considered using fiberglass for that but I was already pushing my rocket's weight a bit; so I'm glad I didn't even if it was a marginal amount of weight.

 

[bad_idea]

For through the wall, preglassed fins, do you also glass the fillet area/put fiberglass connecting your fins to the body? or do you just do fillets? I did the latter for my first HPR... haven't gotten to launch it because of some delays, but I cannot imagine them coming out or breaking unless something goes wrong. I considered using fiberglass for that but I was already pushing my rocket's weight a bit; so I'm glad I didn't even if it was a marginal amount of weight.

For most rockets, I'd just fillet them. For a particularly flexible body tube or particularly protruding or fragile fins, I'd tip-to-tip them. I suspect your fins will be just fine. Good luck with your cert flight!

 

[JoeFilgas]

For most rockets, I'd just fillet them. For a particularly flexible body tube or particularly protruding or fragile fins, I'd tip-to-tip them. I suspect your fins will be just fine. Good luck with your cert flight!

Thank you!

 

[JoeFilgas]

For through the wall, preglassed fins, do you also glass the fillet area/put fiberglass connecting your fins to the body? or do you just do fillets? I did the latter for my first HPR... haven't gotten to launch it because of some delays, but I cannot imagine them coming out or breaking unless something goes wrong. I considered using fiberglass for that but I was already pushing my rocket's weight a bit; so I'm glad I didn't even if it was a marginal amount of weight.

So the way I have decided to go is entirely pre-fiberglass the fins. I’m using West Systems epoxy resin with colloidal filler to glue fins and bond the lower motor mount ring in. I’m going to make the internal fillets out of the same material as it is a strengthening filler. I’ll use the same epoxy filler for the external fillets and I also have a lighter micro filler I may mix in. So the external fillets will be going over the pre-glassed fins and I blend all that in.

 

[bad_idea]

Thank you!

With your V2, you might think of applying some fiberglass over the fillets. Not so much to protect the fins if you already glassed them, but rather to strengthen their mounting. I've seen several accounts of V2s breaking fillets or even popping fins off the motor tube even when the fin itself was undamaged.

For your internal fillets, you might also consider some fiberglass reinforcement. I once built a rocket that way as a deliberate exercise in overbuilding, but for a V2 it might actually be a reasonable decision.

 

[Handeman]

Are you using a LOC 4" V2 kit with a 38mm MMT, I would build it according to the instructions and not bother with all the fiberglass. That kit is designed for L1 motors.
Just be aware of what they say:
For Level 2 motors and large Level 1 motors change the launch lugs to rail guides to eliminate rod whip due to its short height and wide motor mount location. Nose weight will be required.
I would suggest the rail guides to begin with since most clubs these days only use rails, not rods. Sounds like their description of the rocket is a little behind the times, like maybe 10 years behind.

Also, know that, this:
This boat tail kit comes standard with a 38mm motor mount but flies great on F50 and G motors using an optional MMA-2 adapter.
means it flies acceptably on F and G motors. It's going to get some good altitude on H motors and even more on large H and I motors. Even though they claim it can fly L1 and L2, the fact they say it can fly of F and G motors, makes me think this is more of a MPR kit that can do small L1 motors OK.

This can be a great flyer if you use the right motors. I'm not sure it's a great L1 cert rocket. It can be if it's what you want. It's your hobby and your cert and you should do it the way you want. Just know what the parameters of the rocket are. Run lots of sims with lots of different size motors and take a serious look at what altitudes are predicted and analyze what that means at your field and how it affects your chance of recovery.

Good Luck

 

[COSTransplant]

So can I ask a stupiud question -- the OP is using West Systems epoxy resins and fillers. What do most of you use for this type of work?

 

[davidb123]

I have a LOC 4” V2 that loves anything G-I. The problem I have with it is the 1/8” ply fins bonded to a plastic boat tail. The fillets keep cracking slightly even though I put beefy internal and external fillets on it. The plastic is just hard to bond to. The best peace I’ve come to with the model is that it just needs a super big chute. I cut out the bottom of the nosecone and added a bulkhead at the very tip, and stuff the biggest chute I can in there.

OP has got the right idea with tip to tip on this kit in particular. That would also help fix the problem of cracking fillets. Just do some research on laying up over plastic, and make sure you sim it and add nose weight!

 

[rharshberger]

So can I ask a stupiud question -- the OP is using West Systems epoxy resins and fillers. What do most of you use for this type of work?

As long as you use a laminating epoxy it doesn't matter, the two most common ones we seem to see here on TRF are the West Systems and US Composites 635 (my preferred and most economical), Total Boat is also another one recommended by some. The epoxy needs to be pretty thin to evenly soak through the materials. BSI even makes a laminating epoxy the BSI 20minite Finish-Cure iirc.

 

[bad_idea]

So can I ask a stupiud question -- the OP is using West Systems epoxy resins and fillers. What do most of you use for this type of work?

I've used System 3 General Purpose so far. (I also have some Aeropoxy laminating epoxy that I'll try at some point; have their structural epoxy waiting to be tried too.) I use various fillers, some generic, some West Systems, some System 3.

I actually used Bob Smith 30 minute for my first tip-to-tip simply because it's what I had on hand. It worked, but it's thick stuff and by the time I had all the cloth wet, I ended up using a lot more epoxy than I would nowadays.