How much glass ?

[Kcee]

I'm currently starting to glass the airframe on my LOC Big Nuke the payload section now done with one wrap of 6 oz fibreglass with epoxy resin of course looks to be very strong.

I plan on flying this rocket on a CTI L1090 SS which has a total impulse of 4815 NS and a max thrust of 1702 NS this is going to be the most powerfull motor it will see but I'm trying to keep it light enough to fly on a large J and K motors.
Will the one layer of glass be enough for the big L?

Thanks
Kevin C
CAR S569 L3

 

[Neil]

Well.... thats really a matter of opinion, and if anyone else chimes in, listen to them. They have more experience with that heavy glass. But I would say that 2 wraps would be safer, but it could survive a smaller motor on just 1. I am not Mr. Brillian Glass Pro, quite the contrary. Dont quote me on anything I say on fiberglass, other than that it is tough stuff, you should use finish-cure epoxy on it, and you should not leave it sitting on your picnic table while the epoxy dries (that was my first attemt at glassing. Dont inquire further, I will start crying/laughing at the same time. ).Someone else knows better than I do. IMHO 2 wraps would be better. Your choice.

 

[Kcee]

You know a lot for a young lad
I'm looking for a good power to wieght ratio something in the 12# realm that can be flown on a high impulse J to L do the math and it's really not as simple as you think
But you seem to know it all so tell me

Kevin C
CAR S569 L3

 

[Kcee]

Enjoy the ride Niel
This is not a race it's all about design and watching glue and paint dry be patient and enjoy.

Kevin

















kevin

 

[Austin]

Kevin,

I can give you my ideas on glass cloth and how much. To start, I think much of the glassing idea is overkill, just due to some of the writeups I see people trying and with the experiences I have had fiberglassing over the last 20 years or so. I use only 2oz cloth for glassing fins on 4" rockets that handle up to J motors and have never had a glassing failure. I know that seems light but I have glassed entire rockets before with only one layer of 2oz and during one flight I had a NC seperate, which took the chute with it. The model came in without recovery and landed without a scratch, not even a cracked fin and they were only 1/8" ply. This was on a 4" Thoy Phoenix that weighed just over 4lbs and flew on an I161W...I still fly the rocket today. Point is, it doesn't take alot of cloth to help prevent damage and add strength.

For Level 3 models, I guess it would be the equivilent of your CAR L4, I use a single layer of dense 5-6oz cloth on the outside for the fins and for Bodytubes, either two wraps of 6oz or I buy pre-glassed tubing from PML. Most of the fin is glassed and supported on the inside, which allows for a more scale appearance on the outside. Probably the best way to test whether you have enough cloth on a bodytube is to try to compress the tube from the sides. If it gives alot, add another layer.

Note that I do not fly ballistic/mach rockets, in which I would use either G12 or carbon fiber tubing. The best flights you can have are those that run around half of mach for velocity...the model comes off the pad fast enough to be stable and never overstresses the airframe. So many times I have seen people push the edge and wind up overstressing the model...not good. Hope this helps and I hope you are having fun here at the Rocketry Forum!

Carl

 

[Kcee]

Thanks for the reply Carl I feel the same way as you about the over use of glass to get desired strength most of the replies I get are the "enough is good more is better" response.
But you did make a good point regarding mach capable rockets and having enough strength to withstand such a flight
So I did a mass overide in RS 6 and brought the model up to 12 lbs which is close to what it would wieght with 2 layers of 6 oz glass.I then simmed it on a CTI L1090 SS and it still screams and still hits mach. Then I simmed it on a CTI J360 it's a bit of lob but it still flies ok and gets enough rail speed for stable flight, so an extra layer of glass probably would'nt hurt as the L is very unforgiving to this bird with or without the glass.

I glassed the fins with 2 layers of 2.5 oz and the MMT fins and all are going to slid into the booster section and glued and glassed into place I have done other mods to the original kit including a 10" stretch on the booster section to accomadate the longer hybrid motors.
This is my 5th HP rocket and also the largest this is also the first time I've used fibreglass in a build I've used Quantum tube and even PVC for other projects as I like to sand tubes as little as possible
As far this forum is concerned it has been a great resource for me
nice helpfull people that really know thier stuff and the best part?
NO POLITICS just rockets unlike some other forums and NG's.

Hope I can contribute

Kevin

 

[Neil]

Youve built PVC rockets? would you mind telling me more about this sometime... I have a lenth of 4" tube that was GOING to be a rocket, but it started to look impossible, and slightly dangerous, so it is just collecting dust now. How did you do it??? What kinda glue, and how did you keep the motor from taking the motor mount straight up the tube in a big blow-through? It makes sense to me to make good use of the $20 I spent on PVC parts, if I have insight from someone whose done it. Thanks! -Neil

 

[Stymye]

Neil,
try here ,,this site will keep you busy for a while

https://www.nakka-rocketry.net/#Quick Index

 

[Neil]

All I see is PVC Motors, no rockets. I am talking about using PVC as an airframe, not propellant. Ill keep looking. Maybe I missed it. Thanks for the link!

 

[Neil]

OK. I found one reference to PVC airframes. but it was just the subtitle to a picture.

 

[Ryan S.]

www.inverseengineering.com

they usually dont work but sometimes they do. You need to remember he makes the motor in the PVC tube. Also, he makes all his own parts and screws fins on etc

 

[Ryan S.]

o wait he used quicktube for his bigger projects...sorry good site anyway

 

[Neil]

That wasnt a hint, was it... I may have seen that site before... Some google search turned it up. No offense to him, but I would rather listen to someone who has had just a little more success, which he admits he has not. The warning about why I should leave his sight now was pretty funny, but still, a little serious as well.... I dunno. This tube may be collecting a LOT of dust beforfe I decide....

 

[Kcee]

I would be glad to give any imformation you want Niel
Mine was built from a piece of PVC pipe used for electrical conduit they use it for protecting wire that is buried underground it has a 3.25 OD and a 3.062 ID it's reasonably light and very strong. I designed and built the rocket completely from scratch making the CR's fins and bulkheads from .25" birch ply the only parts I bought were 1 Loc tube coupler which I had to put a layer of glass on to fit properly
a LOC 38mm MMT and 2 acme rail guides. The MMT with the fins were slid into the back the booster section and glued with West Systems epoxy resin I had a friend turn me a ogive nose cone from yellow cedar after which I took a speed bore bit and hogged out the center of the nose cone to hollow it out as it turned out to be a little heavier than I thought nose cones are the biggest obstacle when using non standard tubes like this, if you have a friend with a lathe your laughing. I used a RS 4 demo to design the model and used it to cert L2 and L3 on.
Both flights went off without a problem the rocket wieghed almost 6lbs and was brought down very fast on a 3ft chute landing in some very rocky terrian with only a little damage to the paint If you like some build pics let me know.

Kevin

 

[Neil]

Im pretty sure I can make a nosecone out of foam and glass. Though I would like advice on that too....


Mostly I am worried about blow-throughs. Normal epoxy cant stick to PVC. How am I going to get it to stick? I figure if I just fiberglass the heck out of fin/motor mount (whichis made of paper, BTW) joint, it will be strong enough to keep the fins on the rocket. But then the only thing keeping the motor from flying up is the fin tab. Unless..... Maybe if I put a huge mega honkin bulkhead in front of the top of the motor mount it would act as a big engine block. Is that what you did? Maybe some of those screws that hold joints.... You know, those ones that screw through stuff at a *90 angle. If I could screw a few of those into the fin, and the other bit into the outside of the tube, it could hold it on reasonably welll..... I am just thinking out loud here. Please tell me how its really done if you know.... Ive gotta get to bed. My parents want this light out... It gets into thier bedroom. 'Night.


BTW, my names "Neil", not "Niel". When I am in a rush even I spell it wrong (such as when I really gotta pee, or when a rocket just came in the mail and I am trying to type an email or something) . Thanks for the advice! -Niel

 

[Kcee]

The glue will stick just fine Neil
Believe me alot of people told me the same thing they dont know what they are talking about here's proof

Kevin

 

[Kcee]

Pipedream L3 cert on a CTI J300

 

[Neil]

L3 on a J??? Ohhhhh, right. You are a CAR member, and they do it differently, dont they.

Why is that PVC pipe blue/gray? I have only seen white. is there a difference? Thanks. -Neil

 

[BlueNinja]

I think he painted it. Check out NARAM44 R&D reports, Ted Mahler's NO DOG entry.(Not One Drop Of Glue) It was all pvc IIRC.

 

[Neil]

No, I dont think so. unless he used see-thru paint... YOu can still see the words onthe side of the tube.

 

[MarkABrown]

Originally posted by Blue_Ninja_150
I think he painted it...

No, I don't think he painted it. If you look closely at his pictures you can still see the information on the PVC pipe. Schedule 40 PVC pipe is usually white in the USA. I'm not sure what schedule pipe Kevin is using but it is obviously a lot thinner than Schedule 40. If you subtract the inside diameter from the outside diameter that Kevin gave, you'll see that there is only a 3/16" difference. That means that he's got a 3/32" wall thickness on his pipe. Schedule 40 has at least a 1/8" wall thickness, probably more.

 

[Neil]

Toldja.... I think I have 1/4" wall, but I am not sure. Ill check later today. I am not going outside for a loooongg time... its 10 degrees out!

 

[Austin]

PVC EMT Electrical conduit can be found at many stores, including Lowes and Home Depot and it is gray in color. It varies in sizes and they have an entire section just for it, which is usually found in the isle next to the regular PVC, hence it is not as visible. The stuff is pretty thick and is used for above ground apps.

Carl

 

[Neil]

Interesing. Never seen it there before.... Ill have to take a look sometime.

 

[Kcee]

Originally posted by Neil
L3 on a J??? Ohhhhh, right. You are a CAR member, and they do it differently, dont they.

Yes we have 4 Levels instead of 3 I could have flown up to an L if I wanted but why? I believe in the KISS method on cert flights big dumb rocket and keep it low and slow.
I "ll have lots of other oppratunities to screw around with bigger and faster projects. Talk to anyone whose certfied and they will probably tell you the same thing.

Kevin

 

[Neil]

So I have been informed..... I have no taste for a 600' L2 flight. 1K thru 1.5K at least if you ask me. If yer gonna use a motor that big, you might as well have some fun with it! (At one point I was sorely tempted to use a minimum diameter rocket for L2, but that shriveld. Now I am thinking about the 5" bird that is at the bottom of this post. That isnt quite as light and fast, and should get a respectable 2K on a J540R. I consider that a decent L2 flight. Sure, it is a lot higher than Bill Spadafora's 667' Pro38 L2 flight, but he was in the smallest field in the east! Well, its big enough for most MPR, if the rocket is heavy enough. Joel Rodgers was either brave or foolish, and he launched a mega-nuk on a K there. Through some miracle it landed in the main field. That had me baffled. I launched a 4" V2 on an H165, and it landed past two stinkin barbed wire fences for cryin out loud! Well, I suppose mine went twice as high as his, but still...

 

[Manwithbeers]

I've been building a 4" PVC Rocket. 2 stage in fact. I've been using epoxy and CA like Kevin. My PVC is plain old sewer pipe. Lighter than Sch40 by a lot! Mine is a step lighter than sewer in fact as it is a grade called Non CSA. I Canadianian thing I'm certain but likely means it's good as drain pipe and not much else if you actually have sewer in it. I don't so anything goes right? We'll see. I'm going to launch it on a J295I have not tested it yet.

I made (hotwire cutter) my nose cone from expanded poly styrene (beads fused together) but syrofoam, cell fort(sp?) would work. I glassed that and spread epoxy thicked with lightweight filler (West Systems) over the cone like frosting a cake. Then I snaded it to shape. Easy actually with a power sander. Pics can be seen on my meager website at https://oberon.ark.com/~lkvend/rocket.html

Bonding wasn't a problem on the sustainer due to thru the wall fins but the booser uses a thrust plate so bonding the motor mount isn't as problematic (surface mounted fins, glassed onto the tube)

My first Post here. I've gained a lot from this forum. I hope I too can contribute sometime.

Layne

 

[Kcee]

Good to see you Layne