Carbon Nightmare

[mannyskid]

I made the long trip down to Gus's place in order for him to teach me in the ways of the "SLATHER" method. Well, first off I want to thank Gus for the great hospitality, and taking an hour out of his day to show us the way out, because we didn't want to go the way we came in! I also want to thank Gus for generously donateing all of his scrap carbon to me for the future. Sorry for the delay in photos though, I didn't get home until 11:30. I was starting to doze off and needed to pull over and nap for awile, then drink some mt. Dew. And, we needed to make a stop at the aforementioned, HOOTERS. "You guys ate really quickly!" (it's 9 o'clock) "we've got a 3 hour drive ahead of us." The first picture shows me cleaning the airframe under the guidance of Mr. Peipenburg. Since I can only attatch 5 photos per post, here goes. The first photo shows me cleaning up the airframe under the guidance of Mr. Peipenburg. "Listen up kids! Carbon class is in session!" The second is me scuffin the airframe really good to allow that glue to be soaked into the airframe to hold the carbon on. We used some graph paper and laid it over the fins to make some patterns. We then cut out a whole lot of carbon to sacrifice to the AWESOME Gods of Mach! Then we painted the airframe with some wet systems.

 

[mannyskid]

We centered the patterns on the fins and began wetting out the carbon. There are three layers on each rocket. Once they were all wetted out, we laid down the wax paper peel ply. In order to get even preasure on the cloth, Gus gave me his years supply of rice! It looks pretty ugly, but it should look pretty nice once I get it all sanded. The others go on tomorrow and Thursday.

Manny

 

[redsox15]

We centered the patterns on the fins and began wetting out the carbon. There are three layers on each rocket. Once they were all wetted out, we laid down the wax paper peel ply.

Did you use legit peel ply or was it wax paper from the store (like walmart or something)? Also does any of the epoxy seep through the wax paper? Just asking because it would be an interesting substitute to look into.

Matt

 

[mannyskid]

Yes, it is just wax paper, the epoxy generally won't seep through, but it has happened before, when we were doing the tube roll, that happened. The wax paper does work very well though. On a little side note, Gus is loaning me his 7600 case to fit the motor retainer, when I slid that HUGE case in, I just drooled. Although, I am not going to be using the M2300 RR as I don't think it really was ever certified and I can only be there on the commercial days. Instead, I am going to be using a new load that CTI is coming out with, an Imax load for the 6 Gxl case. At over 9000 ns, it sure is going to give this tiny rocket a good ride!

Manny

 

[gtm3323]

So, I left my camera at the shop and hadn't gotton around to posting pics. But here they are. The first two pics show the sustainer fillets. These fillets were done with proline high-temp epoxy (coltronics). The same glue that comes with the mongoose kits. The 2nd and 3rd photos show the fillets on the booster, these were also done with Proline high-temp epoxy (coltronics). The last pic shows the two monsters together. This weekend, it's my turn to make the 5 hour drive to meet Gus and do the carbon tip-to-tip. These fins are going nowhere!

Manny

Manny,
Great looking build thread!
I have a question for you and everyone else since I am working on a minimum diameter rocket myself. Is a tip to tip carbon fiber layup necessary? I simply am not getting it! While in flight the force will be on the leading edge of the fin trying to rip the fin off the rocket?( provided the fins are on straight and the fins have the same thickness on all three sides) If you use the M3500 the max lb-force would be 926lb-force and in flight with the L935 the max force would be 360lb-force. So does that mean it is like taking a 926lb and 360lb sledge hammer to the fins?? I thought epoxy have over 5,000 psi tensile strength? If you just run a 1” wide fillet for a 5” the area of fin fillet would be 5sq-in force on the fins, right? Would the load then be divided over fillet or 185lb-force per sq inch on the fin, therefore a simple fillet should hold the fins on? Am I way off base? I am only a salesman and not an engineer! Thanks!

 

[dixontj93060]

Manny,
Great looking build thread!
I have a question for you and everyone else since I am working on a minimum diameter rocket myself. Is a tip to tip carbon fiber layup necessary? I simply am not getting it! While in flight the force will be on the leading edge of the fin trying to rip the fin off the rocket?( provided the fins are on straight and the fins have the same thickness on all three sides) If you use the M3500 the max lb-force would be 926lb-force and in flight with the L935 the max force would be 360lb-force. So does that mean it is like taking a 926lb and 360lb sledge hammer to the fins?? I thought epoxy have over 5,000 psi tensile strength? If you just run a 1” wide fillet for a 5” the area of fin fillet would be 5sq-in force on the fins, right? Would the load then be divided over fillet or 185lb-force per sq inch on the fin, therefore a simple fillet should hold the fins on? Am I way off base? I am only a salesman and not an engineer! Thanks!

I will pre-answer for Manny... It is not direct force that you are primarily worried about, it is lateral forces on the fins from corrective adjustments during flight (fins doing their job) and wind angle of attack. This force alone may shear the fins, but more likely it could cause the fins, depending on their physical profile to resonate/oscillate to the point of ripping the fins right off. There are two ways to protect against this, 1) use thicker fins, and 2) stiffen the "skin" of the fin structure--the carbon layer does help both while also strengthening the root edge connection to the airframe.

 

[mannyskid]

Tim hit it pretty much spot on. In other words, fin flutter. It's bitten more than a few rockets. But that is not the only reason. Think about the landing, then being thrown in the back of a pick up and being driven around. It's just extra insurance. And besides, the carbon looks really cool! Another little update, all three sides have their carbon and tomorrow I will tack on the ACME rail slides and do the carbon on those. Also, Bruce Lee (vice president of Tripoli, not the Kung fu fighter) emailed me today and he is going to give my number to Discovery/science channel! I could be a big TV star and meet Kari Byron!

Manny

 

[mannyskid]

I got some more work done today. I did some sanding on the booster and tacked the ACME rail slides in place. Then per Mr. Gus's instructions, I put carbon around them to hold them on. While I had some extra west systems, I painted the fin can to give it some shine.

Manny

 

[mannyskid]

The High Altitude Application went out today, fingers crossed it gets aproved! And since my manager BEGGED me to take my shift as she goes back to school in two weeks, I caved and don't have work today so lots of sanding today! Pics later!

Manny

 

[mannyskid]

Some things have come up so it looks like I may be doing something differant at LDRS and this will turn into a BALLS project. Mods, please move this thread to the high powered sub-forum.

Manny

 

[edwinshap1]

ooh, this would be much easier to fly at balls right?

and i've used parchment paper to wrap tubes, no stick from seep through, but i wrap it diagonally really right and the inside can get stuck in some epoxy meaning i gotta scrape it out, but nothing too bad

 

[mannyskid]

I've been making some progress, the "Carbon" part in Carbon Nightmare is looking good, as is the "Nightmare" part. She's starting to look pretty.

Manny

 

[mannyskid]

As many of you already know, this rocket flew as a single stage at LDRS on an L2375 white thunder. It hit 19,000 ft at just above mach 2. The whole two stage thing kind of fell apart. It may fly with the upper half in the future, but in the near future, it is going to fly in my "24,999' contest" at MWP with a Chuck "Frontpage" Swindler M2000 8000ns reaserch load. More to come on that later. As for two stages, Gus and I are already planning a very "Special" two stage for A.I.R fest next year, think O-25000/N-10000. Anyways, takeoff pictures taken by Sather (SMR).

Manny