L3 Airframe Material?

[llobdelljr]

I have had an L2 for 22 years & finally want to try for L3. What airframe material should I use for a 7.5" x 9' rocket? LOC cardboard, fiberglassed LOC cardboard, phenolic, fiberglassed phenolic, Blue Tube, G-12 fiberglass, etc. I know L3 costs $$$$$$ - I have already bought AT 75 mm motor hardware, electronics, GPS, etc., but G-12 fg airframes seem quite spendy.
Thanks!!!!!

 

[Grog6]

FG or CF seems to be the way most people go.
Blue tube would probably move the decimal point, in comparison.

 

[OverTheTop]

One of the great things about rocketry is that you choose what you want to fly, and that goes for cert flights too. Whatever you fly will need to withstand the relevant flight and recovery forces. L3 has indeed been done on cardboard. Quite a few flyers add some fiberglass to the cardboard for strength, longevity and insurance too. Whatever you are thinking of run it past your TAPs to get their go-ahead first.

Don't forget to factor in your skillset and what tools you have to work with.

Composites are popular, but not the only way to fly .

 

[rharshberger]

One of the great things about rocketry is that you choose what you want to fly, and that goes for cert flights too. Whatever you fly will need to withstand the relevant flight and recovery forces. L3 has indeed been done on cardboard. Quite a few flyers add some fiberglass to the cardboard for strength, longevity and insurance too. Whatever you are thinking of run it past your TAPs to get their go-ahead first.

Don't forget to factor in your skillset and what tools you have to work with.

Composites are popular, but not the only way to fly .

Mostly we add the FG to Cardboard for durability...on the trip to and from the field.

 

[Grog6]

I have no doubt the Sentinel Model I bought will still be working well by the time I get to L3 It's incredibly well built cardboard; adding glass or fiber would only add weight and durability.

 

[Titan II]

LOC cardboard...no glass.

 

[Zeta]

I have had an L2 for 22 years & finally want to try for L3. What airframe material should I use for a 7.5" x 9' rocket? LOC cardboard, fiberglassed LOC cardboard, phenolic, fiberglassed phenolic, Blue Tube, G-12 fiberglass, etc. I know L3 costs $$$$$$ - I have already bought AT 75 mm motor hardware, electronics, GPS, etc., but G-12 fg airframes seem quite spendy. Thanks!!!!!

I don't know what your time frame is but the 7.5" blue tube is out of stock.... the 6" blue tube shows 5 pieces in stock (Apr. 3, 2022). It makes for a really tough airframe. The strength to weight attributes are really good and when cost factors into the equation it beats out carbon fiber in my mind. Blue tube will take a hit and CF can crack or shatter.

Zeta

 

[jimzcatz]

My L3 was on a paper rocket, but my go to material is fiberglass now. Its so easy to work with and almost indestructible. Yea, it's a bit spendy but in my opinion well worth it. Any Loc 7.5 kit well suit your needs fine.

 

[OzHybrid]

Why are you going for your L3. What's your reason?, What's your thing.... We all do things for different reasons. Some like kits. Some like building every conceivable part themselves. Some like a beautiiful paint job.. Once you've answered those questions to yourself, you can decide on what materials to use. If you go with feathers and wax, stay away from the sun...... And make sure your TAPS approve of the bird you're plucking feathers from... You can easily glass your own tube, but you're trading time for cash saving. Go with whatever you've got a budget of. time/cash. Curtis does awesome spiral wound GF tube. When it turns up. But it is awesome....
Good luck with the cert attempt

 

[David Schwantz]

I also would go with glass. Built one rocket out of blue tube and never will again. Glass is tough, lightweight (thin wall) ,easy to cut, easy to paint.

 

[JackC]

Go with glass. No need for weight savings when using an M motor. Virtually indestructible unless things really go south (a CATO or drogue charges fail to deploy). Just remember to sand areas you want to join with epoxy and you should be good to go.

 

[Tommie D]

I have had an L2 for 22 years & finally want to try for L3. What airframe material should I use for a 7.5" x 9' rocket? LOC cardboard, fiberglassed LOC cardboard, phenolic, fiberglassed phenolic, Blue Tube, G-12 fiberglass, etc. I know L3 costs $$$$$$ - I have already bought AT 75 mm motor hardware, electronics, GPS, etc., but G-12 fg airframes seem quite spendy.
Thanks!!!!!

I've been rowing that same boat for twenty years, Planning for a 2023 level three. I'm deciding between a full scale ARCUS or a six inch Little John from Composite Warehouse on a Loki M-900.

 

[JackC]

I've been rowing that same boat for twenty years, Planning for a 2023 level three. I'm deciding between a full scale ARCUS or a six inch Little John from Composite Warehouse on a Loki M-900.

I would recommend the full scale Arcas. It’s a long, lean rocket with a very forgiving CG/CP ratio. You won’t need nose weight for it. The Little John is a fairly short rocket with fairly small fins. When you use large motors the CG/CP ratio can get close to unstable. My dad flew a six inch Little John for his L3 and had some coning during the boost. That told me he didn’t have enough nose weight to move his CG toward the nose.
Most people tend to use a lot of epoxy to construct L3 fin cans and that extra weight in the Little John requires a lot of nose weight to move the CG forward.

 

[crossfire]

I used PML tubing with fg nose cone and g10 fins for my L3. Flew it on a AT M1315 single deploy.

 

[mccordmw]

My L3 was an 8" x 13' Quickcrete tube wrapped in FG. Choose whatever materials you are comfortable with.

 

[Hobie1dog]

I guess for people being real cheap skates They always seem to take something like Sonotube or cardboard tubing which has to have fiberglass laid over top of it , a very laborous and costly process, and lots of heavy fiberglass resin to get it to soak in, vacuum bagging, etc. Then you end up with something that is very rough on the surface, takes a whole lot of filling and sanding, and is heavy. Life is way too short to have to spend a portion of it going through all of that stuff, just to end up with something that is still inferior to fiberglass. Fiberglass is the way to go, it's tough as a Gorilla, and has a smooth finish that's ready for paint. That's worth its weight in gold right there.

 

[mtnmanak]

30-weight ball bearings, 3-in-1 oil and gauze pads. It's all ball bearings, these days.

 

[Titan II]

cardboard tubing which has to have fiberglass laid over top of it

That is so inaccurate. Cardboard does not have to have glass over it.

Though money is no object and I could use glass all the time, I like working with cardboard and ply to keep the weight down for long burn motors.

 

[rharshberger]

That is so inaccurate. Cardboard does not have to have glass over it.

Though money is no object and I could use glass all the time, I like working with cardboard and ply to keep the weight down for long burn motors.

And adding a wrap or two of 6oz glass weighs very little more but greatly increases the durability of the cardboard (talking transport and or landing damage resistance).

 

[JackC]

And adding a wrap or two of 6oz glass weighs very little more but greatly increases the durability of the cardboard (talking transport and or landing damage resistance).

I also find phenolic tubing wrapped with fiberglass cloth is strong and fairly light weight. It is great for transport and landing damage, too. It’s also fairly easy to wrap it yourself or you can have Public Missiles (now owned by Loc Precision) sell it to you.

 

[manixFan]

I used PML phenolic 6” tubing with several layers of fiberglass for my L3 airframe, and 1/4” plywood, also with several layers of fiberglass, for the fins. Plenty strong enough. Since then I’ve built rockets with both wound fiberglass and carbon fiber, and while easier, a lot more expensive.

I got a lot of satisfaction knowing my L3 rocket had a lot of my labor and learning in it, which I feel helped pave the way to my more complex rockets and flights. Do what feels right for you and you won’t regret it.


Tony

 

[cerving]

I know somebody who made their L3 out of three 55 gallon drums, and used 3/4" ply for centering rings and fins. The ultimate short stubby rocket... it went maybe 2,000' on an AT 75/6400. No tracker needed on that one...

 

[rharshberger]

I also find phenolic tubing wrapped with fiberglass cloth is strong and fairly light weight. It is great for transport and landing damage, too. It’s also fairly easy to wrap it yourself or you can have Public Missiles (now owned by Loc Precision) sell it to you.

Especially phenolic as its pretty brittle, not sure about the flexible phenolic though.

 

[Philip Tiberius D.]

Don't forget MAC Performance and canvas phenolic tubing, have flown many rockets on this material. Great stuff!!!!

 

[DAllen]

I guess for people being real cheap skates They always seem to take something like Sonotube or cardboard tubing which has to have fiberglass laid over top of it , a very laborous and costly process, and lots of heavy fiberglass resin to get it to soak in, vacuum bagging, etc. Then you end up with something that is very rough on the surface, takes a whole lot of filling and sanding, and is heavy. Life is way too short to have to spend a portion of it going through all of that stuff, just to end up with something that is still inferior to fiberglass. Fiberglass is the way to go, it's tough as a Gorilla, and has a smooth finish that's ready for paint. That's worth its weight in gold right there.

This post makes me laugh.

Anyways...I got my L3 with a LOC 7.5" Goblin. So there's that. Build your L3 the way that makes you happy FFS and find some TAPs/L3CC folks that will go along with what you are doing. Some people like spending time glassing everything up - nothing wrong with that at all. If it works and falls within prescribed safety parameters who cares? I love working with paper and cardboard. I have plans on doing a 8" sonotube rocket sans glass this summer.

 

[David Schwantz]

I have built up to 16" sonotube rockets. No glass on it. The V 2 is 12" dia and weighs 68 lbs and flies on M2050X. Although that one is glassed.

 

[SDramstad]

Another vote for Loc cardboard with 2 wraps of 6 oz fiberglass cloth. Strong and light

 

[llobdelljr]

I guess for people being real cheap skates They always seem to take something like Sonotube or cardboard tubing which has to have fiberglass laid over top of it , a very laborous and costly process, and lots of heavy fiberglass resin to get it to soak in, vacuum bagging, etc. Then you end up with something that is very rough on the surface, takes a whole lot of filling and sanding, and is heavy. Life is way too short to have to spend a portion of it going through all of that stuff, just to end up with something that is still inferior to fiberglass. Fiberglass is the way to go, it's tough as a Gorilla, and has a smooth finish that's ready for paint. That's worth its weight in gold right there.

This is not accurate. Three years ago I made a 4" dia rocket of LOC cardboard. Used a Soller Composites FG sleeve & their heat shrink. Came out super smooth. - no sanding needed. No painting needed either because I bought their tinted sleeve. Only thing is epoxy is quite messy

 

[ghostfather]

Any cardboard or phenolic airframe larger than 54mm gets a layer (or two) of glass, they are just so much stronger
especially if it's for a level 3

 

[Zeta]

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