To fiberglass or not?

I am getting ready to build a 5.5" LOC Sandhawk, and I am conflicted with whether I should glass it or not. My original plan was to glass it, but now I am seriously considering a somewhat lightweight build and using couplers to stiffen the airframe. In the end, It probably wont be any lighter, and both build options will probably be able to take the same range of motors.

Thoughts?

Glassing it will give it a little more protection when it comes to hangar rash and handling dings.

Flyfalcons said:

Glassing it will give it a little more protection when it comes to hangar rash and handling dings.

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That's the only main positive I can think of

Glass is your friend. I've done more handling damage than I care to think about simply moving, packing and storing rockets than I care to think about...

If anything, it's always a good learning experience to glass an airframe. I wrapped my Warlock & even did a T2T and it has survived some pretty ugly landings!

timbucktoo said:

If anything, it's always a good learning experience to glass an airframe. I wrapped my Warlock & even did a T2T and it has survived some pretty ugly landings!

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100% concur, but it will add weight. You have to decide. Strength vs. Lower weight.

Just go for it! Even just one wrap of 2 oz glass will make a dramatic difference. I started glassing airframes last year, and really enjoyed learning the technique. Here’s a few threads about it. (I was embarrassingly obsessive about it.) The last thread documents some strength testing that I did to compare 2, 4, and 6 oz glass.

https://www.rocketryforum.com/showthread.php?136266-Glassing-my-first-tube

https://www.rocketryforum.com/showthread.php?139767-Do-I-need-a-rotisserie

https://www.rocketryforum.com/showthread.php?138421-No-More-Peeling-Tubes-for-Me

https://www.rocketryforum.com/showthread.php?136881-Glassed-Tubes-Data

Glass it! and give it a 98mm MMT then you can fly a lot of different motors. My Cherokee-D L3 project was LOC 5.38 glassed, and it only weighs 35lbs at the pad.

rharshberger said:

Glass it! and give it a 98mm MMT then you can fly a lot of different motors. My Cherokee-D L3 project was LOC 5.38 glassed, and it only weighs 35lbs at the pad.

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Nah, sticking with the stock 75mm mount. I have another plan brewing with a 98mm!

Glass it with at least 2 wraps of 6oz or better,anything less on a rocket of this size is just cosmetic.[my opinion,not the law....lol]

Glassing will add hoop & compression strength to the tubes. Can come in handy during hard landing or ugly deployments on heavier birds like this.[helps prevent zippers]

Yes the only reason, is to save your pride & joy from early demise...due to unlucky circumstance.
During travel or flight. That's reason enough for me

If you are new to this a tubular "sock" is nice way to learn. Just place airframe in sock, pull tight on each end ,& saturate will resin. Will add about 2-3lbs on project this size when done with brush/roller.

If you vacuum bag your easily loose a lb.

Unless going for maximum performance glassing a sport rocket is fairly simple.[especially with youtube these days]

I've glassed before, just been awhile! I went ahead and ordered some sleeving from Soller.

I’d keep it light. Gives you more motor options on the lower side.

grouch said:

I’d keep it light. Gives you more motor options on the lower side.

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Thats my goal. I think I am going to go with a layer of the light sleeve from Soller Composites. If I do that, it should give me a happy medium between both worlds.

Absolutely do it. You will discover that the nose cone no longer "fits" so nicely wit the the o.d. of the tube though. There is a a simple fix if it bothers you and as soon as I can find it I'll post pics..

The Sandhawk has swept back fins. You probably won't see problems in flight, the problems will occur upon landing.

My advice would be to glass the fins. Do a T-T on 'em. Cuz Murphy is a son-of-a-gun, and if he gets half a chance, he'll bite you on the butt.

Well, I glassed it! I wont be doing a t-t job on this, but I will be glass reinforcing the fin installation.

Looks great!

Wallace said:

Absolutely do it. You will discover that the nose cone no longer "fits" so nicely wit the the o.d. of the tube though. There is a a simple fix if it bothers you and as soon as I can find it I'll post pics..

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Is there a simple fix for smoothing the step between a NC and a glassed body tube? I’ve wrapped layers of FG on the end of the NC, and then sanded the heck out of it using liberal amounts of bondo. If there’s an easier way, I’d love to hear it.

BDB said:

Is there a simple fix for smoothing the step between a NC and a glassed body tube? I’ve wrapped layers of FG on the end of the NC, and then sanded the heck out of it using liberal amounts of bondo. If there’s an easier way, I’d love to hear it.

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I don't know any other method than sanding, like you mentioned. for this build, I am actually not going to be using the LOC nosecone, and have purchased a Madcow filament wound one. With the LOC nosecone, the mismatch between the tube and the cone is not bad. A little sanding and bondo would probably knock it out completely. With the fiberglass cone, the difference is even less, and as such, I think I am leaving it alone.

At this point, I think I might as well turn this into a build thread! Thoughts?

BDB said:

Is there a simple fix for smoothing the step between a NC and a glassed body tube? . If there’s an easier way, I’d love to hear it.

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krislhull said:

I don't know any other method than sanding, Thoughts?

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There is a simple fool proof way to match any Nose cone to the body tube.

Draw a vertical line at top of tube where cut will be. [about 1-1 1/2 inch slice] the line lets you get perfect fit every time ,by lining up the marks. Make better key mark later with punch, drill, dremel etc.



Cut the slice off tube and glue it to top of NC shoulder.
Use old credit card/something flat, and fill the joint with epoxy & filler. JB weld already has needed filler and easy to use. Hold card with epoxy and spin tube at joint. May take a time or 2 but the joint will disappear. Now when you match up cone & airframe joint is truly invisible.



Now your actual joint is tube to tube, imperfections get feathered in permanently at shoulder to slice joint. Problem solved.

This IS rocket science after all!....LOL .
I bet I post this at least once every year...lol

This tip should get a ton of Likes guys!!

blackjack2564 said:

There is a simple fool proof way to match any Nose cone to the body tube.

Draw a vertical line at top of tube where cut will be. [about 1-1 1/2 inch slice] the line lets you get perfect fit every time ,by lining up the marks. Make better key mark later with punch, drill, dremel etc.

View attachment 357905

Cut the slice off tube and glue it to top of NC shoulder.
Use old credit card/something flat, and fill the joint with epoxy & filler. JB weld already has needed filler and easy to use. Hold card with epoxy and spin tube at joint. May take a time or 2 but the joint will disappear. Now when you match up cone & airframe joint is truly invisible.

View attachment 357907

Now your actual joint is tube to tube, imperfections get feathered in permanently at shoulder to slice joint. Problem solved.

This IS rocket science after all!....LOL .
I bet I post this at least once every year...lol

This tip should get a ton of Likes guys!!

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Crap why do I always overthink these issues, of course this is the way to do it. I guess I don't need to build that sanding jig after all.

that is a nice way to do it! I like that!

Yes it is & it will work with any fiberglass technique....sleeve, vacuum,wraps.....now go back & hit the like button! That's all I charge for my tips...LOL

Ya know, I am the laziest builder out here...that's why I'm always figuring out the easy way to do stuff!!

[that & a couple of my Wal-Mart Pina Colada's] all are inspirational.

Well, I discovered today that I hate bondo with a passion... Not a fan. Anyone have any tips or tricks to working with it to fill weave on tubes?

krislhull said:

Well, I discovered today that I hate bondo with a passion... Not a fan. Anyone have any tips or tricks to working with it to fill weave on tubes?

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Its easier if you use a veil layer of 2oz cloth over the top of the heavier glass cloth. I am not sure if you can thin Bondo, but for sanding it I use a wood working lathe with the tube mounted between centers in adapters made for that purpose.

rharshberger said:

Its easier if you use a veil layer of 2oz cloth over the top of the heavier glass cloth. I am not sure if you can thin Bondo, but for sanding it I use a wood working lathe with the tube mounted between centers in adapters made for that purpose.

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That would work great... if I had a lathe! I guess lots of elbow grease is in store for this one.

I just did a Google on thinning Bondo and evidently you can use polyester FG resin as a thinner (prior to mixing hardener) since its the same/similar as the resin in Bondo and the hardener will still work, the filler will be easier to spread.

+1 for the veil layer. Even that will leave a little texture, but it can be filled with a thin coat of laminating epoxy.

rharshberger said:

I just did a Google on thinning Bondo and evidently you can use polyester FG resin as a thinner (prior to mixing hardener) since its the same/similar as the resin in Bondo and the hardener will still work, the filler will be easier to spread.

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Looks like I will have to try that!

I talked to someone that used acetone to thin the bondo used to fill the fiberglass weave on his rocket. I'll be trying that on my next Polecat build.