To glass, or not to glass, that is the question...

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

ckjohnson

Well-Known Member
Joined
Oct 19, 2013
Messages
307
Reaction score
0
Okay, let me start this off by saying I have searched and searched for information on this, but keep getting way more information than is practical. Also, throughout all of my searching, I understand that there is a contingency of members who do not believe in glassing and are actually against it. I don't want to start a debate on whether the rocket gods will frown upon me for using fiberglass on my rocket. I'm not asking how to do it, I have found plenty of resources on that. HERE, is my question:

I am considering doing my L3 launch next year, and am deciding on which rocket to go with. I have looked at a number of fiberglass rockets. I did my L1 & L2 with my Loc Norad Pro-Maxx, so naturally I am happy with Loc and looking at them again. The Hyperloc 1600 is listed for handling an M motor, and is set up for dual deploy. The question is do I have to fiberglass it? I understand that glassing increases the strength of the rocket, but at what point do I need to increase it? Just completely looking at the cost of flying at level 3, I don't foresee myself launching continuously at M or above. One of the reasons I like the Hyperloc 1600 is because it set for an M motor, but I can put an adapter in it and launch it on an I600 or J motors after I complete my L3. I would like to keep it lighter (without the fiberglass) so that I can launch it on less expensive (notice I didn't say inexpensive) J motors.

So, again, do I need to fiberglass it for an M1297? Rocksim is showing that it would only pull 19.6 Gs and reach 854 mph (supersonic).

Thanks for any helpful input.
 
On extreme flights (>Mach 2) lamination is important. Below that, all you need is good solid construction techniques and verifying your fin profile/materials are not flutter-prone. Saying that, I still laminate most builds simply for long-term durability. I have nearly always been disappointed by not glassing, and seldom, if ever, by glassing.
 
I put some form of composite on all my rockets solely for durability. If I drop it, the ground should be afraid... :p
 
.

So, again, do I need to fiberglass it for an M1297? Rocksim is showing that it would only pull 19.6 Gs and reach 854 mph (supersonic).

Thanks for any helpful input.


Yes.....

One of the perquisites for becoming L-3, is the ability to answer that question. If not able to, then research the answer. So good for you on that point!

Most problems come from the shock wave forming at .75-85 mach....in any case you want to push through fast and not linger in the transition.[in or out of] This often overlooked ,& the thinking Mach itself, is the issue. It is not.... all of it is.

760 mph is the magic number and you show being well above that.

There are re-enforcement methods, full length couplers glued in for one. BUT if you wish to guarantee [or should I say, Improve your chance of success dramatically....glass it!]

I believe the Hyper Loc is a 4in kit? I have seen many large 5.5 & up cardboard rockets survive L-3 flights. [Without re-enforcement]

Can't recall seeing a 4in make it with out shredding & I have seen 4-5 of those!

It's not that difficult to glass...especially if you use a sock. Pull it over the tube, soak with resin & done. Done correctly you should only add 1-1.75 lbs to your project.
 
Last edited:
On extreme flights (>Mach 2) lamination is important. Below that, all you need is good solid construction techniques and verifying your fin profile/materials are not flutter-prone. Saying that, I still laminate most builds simply for long-term durability. I have nearly always been disappointed by not glassing, and seldom, if ever, by glassing.

Thank you! I know that glassing just the fin can will pull the CG back toward the CP, but I was thinking about just glassing the fins to ensure they aren't negatively affected by supersonic flight. This rocket isn't going to reach Mach 2.
 
Yes.....

One of the perquisites for becoming L-3, is the ability to answer that question. If not able to, then research the answer. So good for you on that point!

Most problems come from the shock wave forming at .75-85 mach....in any case you want to push through fast and not linger in the transition.[in or out of] This often overlooked ,& the thinking Mach itself, is the issue. It is not.... all of it is.

760 mph is the magic number and you show being well above that.

There are re-enforcement methods, full length couplers glued in for one. BUT if you wish to guarantee [or should I say, Improve your chance of success dramatically....glass it!]

I believe the Hyper Loc is a 4in kit? I have seen many large 5.5 & up cardboard rockets survive L-3 flights. [Without re-enforcement]

Can't recall seeing a 4in make it with out shredding & I have seen 4-5 of those!

It's not that difficult to glass...especially if you use a sock. Pull it over the tube, soak with resin & done. Done correctly you should only add 1-1.75 lbs to your project.

The Hyperloc 1600 is a 5.5" kit.

https://shop.locprecision.com/product.sc?productId=150&categoryId=16

Thank you for the help Jim. I'm confident that I could successfully fiberglass it, but would like to keep the weight down. I have found a great deal of resources on glassing both here and Apogee.

The graph for the flight shows that it will punch through the transonic region in less than a second. It will break the barrier and be back below supersonic in less than five seconds.
 
Blackjack2564, I am assuming it is just the fin can and fins that need to be glassed? I believe that for what this rocket is going to do, I should be pretty safe just glassing the fins and the joints between the fins / motor tube and the fins / fuselage.
 
Last edited:
I understand that there is a contingency of members who do not believe in glassing and are actually against it.
While I'm sure one can find someone to advocate any position, I don't recall anything like a "contingent" against reinforcement as a technique.

So, again, do I need to fiberglass it for an M1297? Rocksim is showing that it would only pull 19.6 Gs and reach 854 mph (supersonic).
No, unreinforced cardboard rockets routinely go Mach 1. If you read more on the subject, you will realize that those of us advocating it do so for durability (transportation and landing), not for in-flight stresses.
 
Thanks John. I didn't mean anything negative saying there is a contingent. In looking for answers, I noticed a couple of posts that got a little heated having this discussion. I did not want to start another of those discussions here, which is why I stated that. I did not mean to insult anyone, and am sorry if I did. It was not my intention.

Thank you for your reply, your answer is precisely what I was looking for.
 
CJ pretty much nailed it. The largest danger point is the transonic region. Get through that fast.

I certainly would do a two layer tip to tip on the fins. Beyond that, it depends on how long you want the rocket to last, in my opinion. If it were me I would glass the whole thing. Two layers of six ounce glass, quality epoxy, and heat shrink tape. This is after you peel the pesky wax/ gloss layer off of the tubes as epoxy does not stick so well to that.


Mark Koelsch
Sent from my iPhone using Rocketry Forum
 
I would suggest being more sparing with the use of glass. Unless you have severe adhesion issues, the part of tip-to-tip that is not near a fin is simply wasted. I would reinforce the root and reinforce the central part of the fin and that should be sufficient, at perhaps less than half the weight of tip-to-tip.

When the limit is adhesion and not material strength, then you need large areas and that is where tip-to-tip comes in.
 
This is what I don't get myself. I have read the old stories of the guys that built large paper kits with wood glue and successfully flew L3 flights. Kits like the Bruiser should be just fine un-glassed. I am steering my builds from here on out with paper and wood glue for the most part. My new 4" build is all wood glue. It will only have epoxy fillets, no glass at all. I have need glassed a rocket to date and don't really intend on doing it mostly because I like to keep things simple.


Because I am addicted, this is coming from my phone.
 
Everyone: I really appreciate the input. I know just enough about aerodynamics to be dangerous. It was part of my degree, but supersonic flight and, more importantly, transonic flight made my head spin. I'm an airport manager, not a flight engineer!

Anyways, John really answered my question. I was concerned that there was some secret barrier that I might be running into going to my L3 with the big rocket. I know very well that a non-reinforced rocket will do fine supersonic, my Norad went to 826 mph on my L2 launch. I just noticed that so many people were talking about glassing their L3 rockets, and I wanted to be sure that I wasn't missing something.

I'm sure the Hyperloc 1600 will do just fine without glass. Barry has it listed as a rocket capable of M flights, and it doesn't say it needs to be glassed. I'm not too terribly worried about them being damaged in transport or storage. I built a rack and cover for transporting my rockets, and at home they get wiped down and displayed in my living room & aviation rooms (the advantages of being a bachelor home owner, I don't have anybody to tell me I can't display my rockets in my living room).

Again, thanks for the input.
 
Here's the problem; once you glass an airframe and fins, you become hooked. You cannot see another bare-bones cardboard airframe. Soon you will see that rocket covered in primer and paint are weak, and you will feel the need to glass it, if only for your own peace of mind. The real problem arises over time... The time when you look at getting a new kit... lets say are 'larger' kit, and becuase you are now glassing everything, you begin to dread the new purchase... the sanding, The mixing of epoxy, the gloves and brushes, the layering and the stretching etc etc. Eventually you succumb to the dark side and purchase your first all fiberglass rocket from Rocketry Warehouse, Wildman or Mad Cow rocketry and you are ruined... Fiberglassing is a gateway step to a better way of building rockets.

I glass everything that flies high power only...
 
I've been running some simulations, and as it turns out, the motor I want to use in the HyperLOC is going to keep it subsonic. I'm planning on launching it on an M650W. The max velocity in Rocksim is 745 mph, keeping it subsonic, but the predicted maximum altitude is 13,693'. I love the long burn time motors, and this one should do nicely!

Also, I sent Barry over at LOC an email that I was sending this up as my L3, so he traded out the 1/4" fins and replaced them with 3/8" fins for me, and traded out the coupler for a stiffy coupler. THANKS BARRY!!!
 
For the purposes of ensuring a successful attempt, I would recommend against pushing a rocket that fast and that high. For L1 and L2, the operative phrase is "Low, slow and dumb" to max your chances of success. Obviously, you have to drop the "dumb" part for L3 since electronics are required, but "low and slow" still applies. This would, of course, prevent you from flying the rocket on I600s later, however, due to the mass/drag required to keep it low and slow, but, for me, that's preferred over risking having to build and rebuild and rebuild a cert rocket. Not to mention the expense of multiple M1297s.

That being said, I did my L2 on a 4" dual deploy Blue Phenix w/ a 54mm J motor. I failed on my first attempt and had to rebuild and try again. Lesson learned. I should have done it on the LOC 7.67" Warlock with a J350 and saved my dual deploy flights til later. I've since flown this same rocket on several I impulse motors for some nice dual-deploy action.

My L3 will be a 10" Thumper and should come in at a nice, hefty 40-45 pounds. I'd love to keep it under 4000", but we'll see.
 
Last edited:
M650 isn't far off the bottom of the M impulse range (15-20% M) and is low thrust so effectively you're telling him to build a whole new rocket...

CK - do your cert the way you want to do it....
 
Thanks Zebedee, I intend to. :)
My L2 rocket went to 6058' @ 826mph. It is also dual deploy. I'm not worried about altitude. If recovery fails at 8,000' or 13,000', the rocket is equally as screwed.
As far as "low and slow", this is about as low and slow as this rocket will get. I am going with that low M so to reduce the structural stresses on the rocket, meaning I don't have to glass the entire thing, which means the weight will be a few pounds lighter, and the rocket will fly on less expensive J motors, and even some higher end I motors.
Thank you everyone for the input. I have gained some great insight here, and have found a path that I believe will work well and produce a nice L3 certification flight.
 
Back
Top