Playin' With Fire - Flight Report

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daveyfire said:
usz36ZX.gif


Dude that looks awesome, Alex. Keep it up!
Click to expand...

Hey, I was saying that they look incredibly awesome in the photos.
 
stealth6 said:
Tell me about that nosecone tip in the photo. I see it has a shoulder on it - UNLIKE any of the tips on my FWFG cones (I have three of them). On mine, it drives me completely insane getting them to go on straight, and/or to stay on straight. I'm talking foaming-at-the-mouth, screaming-and-shaking-my-fist-at-the-heavens kinda nuts. Very frustrating. I wish they had a shoulder on them like yours. So, what's the deal with yours?

On another note: I won't be making it up to the Feb UROC launch - gotta go to the dentist, have him torture me, and take all my money. Way more fun than flying rockets, let me tell ya.
Click to expand...
The NC tip came with my Wildman 2.1in darkstar. TONS nicer then the ones without the shoulder. I think they're just on the 2.1in ones. To fix your shoulder problem have you tried putting two washers spaced apart on the allthread? The once closer to the tip could have a smaller OD and hypothetically it would center itself.
:( Sad you can't make it out to the February launch you've always been one of my favorite people to see out there. We'll miss you!
CarVac said:
I understand the need you feel to make it better; flaws in CF rarely show up in photographs so I'm guessing the tube looks less incredibly awesome in person.
Click to expand...
No, it looks just like that in person. It just doesnt feel like you think it should. It might be the way I applied the clear cloat. It didnt spread out evenly but the mist created a slight texture on the tube. It may have been because it was too cold. Once it warms up. I'll sand the tube down with 1500 grit and try again.
daveyfire said:
Dude that looks awesome, Alex. Keep it up!
Click to expand...

Thanks for the compliments everyone and whatever Carlo said!

Alex
 
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daveyfire said:
Probably shoulda gone with that phrasing the first time around then ;)

It's too bad it's so pretty... now the rocket gods have that much more reason to give Manny's motor a hard time!
Click to expand...

Aww, don't say that! Now it's bound to happen!

I've done some preliminary simulation and I like what I see. I'm planning on making it Tiger Tail, since I don't feel comfortable branching out yet. I'm starting to think about building a thrust stand with a load cell data logging to an Arduino board. I don't know too much about it and have to do some more research, but my room mate Joel was able to make a data logging thermocouple using an Arduino board, so that gives me some confidence. I promise you Alex, there is a 99% chance your rocket won't CATO. If I find problems while testing the motor, there is always plan B.

Burnsim is giving me about 8300 Ns out of a 7600 case with pretty tight cores for about an M2100.
 
Regarding CF layup for tubes, how do you source accurately sized mandrels? S'there a place that carries workable tooling for a reasonable price, or do you need a lathe?
 
mannyskid said:
I promise you Alex, there is a 99% chance your rocket won't CATO. If I find problems while testing the motor, there is always plan B.
Click to expand...
Well now I'll have to think up some excuse for lawn-darting your case!
Zeroignite said:
Regarding CF layup for tubes, how do you source accurately sized mandrels? S'there a place that carries workable tooling for a reasonable price, or do you need a lathe?
Click to expand...
For standard tube sizes you can use a full length coupler that would fit the desired tube ID.

Alex
 
I was going over this design with Ryan (FrozenFerrari) and he pointed out that I was very overstable after motor burnout (3 cals or something). This could result in serious issues like weathercocking, coning and others. Not ideal.
I spent a few days reworking the design entirely. The fins will have to be shortened and instead of standard dual deploy, I'll be doing the same thing as my Peacemaker (Deploying out of the NC using a cable cutter) This is all to lower stability at low mach numbers.
With the revised the design I am now at 2.37 cal with an empty case and .6 cal at Mach 2.5 (estimated max speed). I'm estimating the limit for this is Mach 2.8.

Here is the redesigned file:
View attachment PWF STABILITY .ork

I'd appreciate feedback on the design and what changes I can make to improve it.

Alex
 
Aksrockets said:
I was going over this design with Ryan (FrozenFerrari) and he pointed out that I was very overstable after motor burnout (3 cals or something). This could result in serious issues like weathercocking, coning and others. Not ideal.
I spent a few days reworking the design entirely. The fins will have to be shortened and instead of standard dual deploy, I'll be doing the same thing as my Peacemaker (Deploying out of the NC using a cable cutter) This is all to lower stability at low mach numbers.
With the revised the design I am now at 2.37 cal with an empty case and .6 cal at Mach 2.5 (estimated max speed). I'm estimating the limit for this is Mach 2.8.

Here is the redesigned file:
View attachment 164652

I'd appreciate feedback on the design and what changes I can make to improve it.

Alex
Click to expand...
is that stability information coming from openrocket or from RASAero?
 
CCotner said:
is that stability information coming from openrocket or from RASAero?
Click to expand...

Openrocket. RAS seems very, very optimistic when it comes to stability. OR seems pretty pessimistic. I like to look at both but I'm more comfortable following the pessimistic one. Better safe then sorry.

Alex
 
Work resumes on this today. I completely resigned the file with the help of FrozenFerrari. Thank you Ryan! The new fin profile is specifically designed for a Mach 2.5- Mach 3 flight profile. They have an extremely long root chord to keep stability at high velocities, while having an extremely short span to keep it from going over-stable at low velocities. I also opted for an extremely flutter resistant shape. With the long root chord and short span, I doubt these will encounter that much flutter.

The design file is attached below.
View attachment 172695

I've cut the first two fins and I'm surprised how small they feel.

image.jpg

image.jpg
Here's one is next to the previous fins.

Alex
 
I cut all the fins out of .1in carbon fiber I bought off of Upscaler. The fin plate is comprised of 0/90° oriented unidirectional fibers. The sheet isn't made from a cloth so it doesn't look like traditional carbon fiber. Much like the previous fins, I cut them out with a jigsaw, beveled them and attached them with Aeropoxy structural.
IMG_0073.jpg
When doing fins with nothing but straight lines, I like to use a little jigsaw guide that I can rest the edge of the saw up against. It's just easier to get a good straight edge the first time and not have to worry about stack sanding as much.

The fins were cut:
IMG_0077.jpg
IMG_0080.jpg
Hand beveled:
IMG_0087.jpg

And attached:
Here the fincan is next to the previous one.
IMG_0088.jpg

More in the next post.

Alex
 
Moving right along....
It's fillet time. I opted to go with JB weld based on some very positive recommendations about the strengths and heat characteristics. I fell that this is a much safer bet then the Proline 4100 I would have used otherwise, which has unknown strength and heat properties.

They're just like any other fillets...
The fillet areas were masked:
IMG_0101.jpg

Then I poured Jb weld into the fillet area and shaped it with a 1/2in piece of PVC
IMG_0102.jpg

Here it is all put together.
IMG_0091.jpg

IMG_0092.jpg

I like the new fins. It gives it a certain missile-y sounding rocket look.

Alex
 
This project has been pretty impressive throughout, but seeing these fincans and your methods, you've clearly moved onto a new level of craftsmanship. Awesome, man! https://d24w6bsrhbeh9d.cloudfront.net/photo/aEwp1pn_460sa.gif

I agree with your reasoning for choosing JB weld over the Proline; I've found multiple datasheets of the proline that were contradictory, and I've never really found a manufacturer that makes it; only retailers for it. Without reliable data, it's a little frightening to use, even though lots of pros use it. My experience with Jb weld has been strictly positive, with one exception; it's a little brittle. Hopefully it isn't a problem for you; with fins that stiff and small, it shouldn't be.

The fin material you have is sort of made from cloth, just not woven cloth. The panel is made by taking unidirectional fabric (something like this https://i01.i.aliimg.com/photo/v1/280156977/carbon_fiber_prepreg_prepreg_carbon_fabric_prepreg.jpg) and adding layers at 90 degrees away from the layer before.
Some of the differences relative to a panel with an identical number of fibers in each direction made from woven fabric:
  • Lighter weight: flatter layers of fiber mean it probably has a lower amount of resin.
  • Probably thinner: maybe, but by the same reasoning as the lighter weight argument, the panel could be thinner than an equivalent woven-cloth panel. This means it might be less stiff by a tiny bit.
  • Possibly stronger-no fibers are pinched in the over/under pattern, since there isn't one. I don't know if this is really a big deal, but when I've snapped CF weave panels, they crack at the over/under points.
  • The all-uni panel will probably fail by delamination, where the UNI layers split apart. Woven layers have regions where fibers in layer n of the laminate and layer n+1 are touching and in the same direction, which bonds the layers of fabric together better.

*Disclaimer: I think you made a great choice of fin material, just thought I'd provide some (possible false) information on the material.
 
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CCotner said:
This project has been pretty impressive throughout, but seeing these fincans and your methods, you've clearly moved onto a new level of craftsmanship. Awesome, man! https://d24w6bsrhbeh9d.cloudfront.net/photo/aEwp1pn_460sa.gif

I agree with your reasoning for choosing JB weld over the Proline; I've found multiple datasheets of the proline that were contradictory, and I've never really found a manufacturer that makes it; only retailers for it. Without reliable data, it's a little frightening to use, even though lots of pros use it. My experience with Jb weld has been strictly positive, with one exception; it's a little brittle. Hopefully it isn't a problem for you; with fins that stiff and small, it shouldn't be.

The fin material you have is sort of made from cloth, just not woven cloth. The panel is made by taking unidirectional fabric (something like this https://i01.i.aliimg.com/photo/v1/280156977/carbon_fiber_prepreg_prepreg_carbon_fabric_prepreg.jpg) and adding layers at 90 degrees away from the layer before.
Some of the differences relative to a panel with an identical number of fibers in each direction made from woven fabric:
  • Lighter weight: flatter layers of fiber mean it probably has a lower amount of resin.
  • Probably thinner: maybe, but by the same reasoning as the lighter weight argument, the panel could be thinner than an equivalent woven-cloth panel. This means it might be less stiff by a tiny bit.
  • Possibly stronger-no fibers are pinched in the over/under pattern, since there isn't one. I don't know if this is really a big deal, but when I've snapped CF weave panels, they crack at the over/under points.
  • The all-uni panel will probably fail by delamination, where the UNI layers split apart. Woven layers have regions where fibers in layer n of the laminate and layer n+1 are touching and in the same direction, which bonds the layers of fabric together better.

*Disclaimer: I think you made a great choice of fin material, just thought I'd provide some (possible false) information on the material.
Click to expand...

Thanks for the input Chris! Always a pleasure to have you following along.

Qquake2k said:
That sure looks sleek, Alex!
Click to expand...
Thanks, Captain!

Alex
 
Last edited:
Onto the T2T portion of the build. Personally, this is my least favorite thing to do with carbon fiber. There's a lot more prep and cleanup then making something like, say... fin stock or tubing. However it is extremely, extremely necessary. I'll be doing a 3 layer 1/3, 2/3, full style layup where each layer is slightly larger then the other. Creating an airfoil. I cut out paper templates of each layer of carbon fiber.
IMG_0108.jpg

Traced them onto the fincan using a silver sharpie.
IMG_0109.jpg

I've actually finished one side of T2T and I can say it turned out really well. I wasnt able to take pictures but I will when I do the next side.

Alex
 
10386862_571178752995348_2753491819136503714_n.jpg


I had a feeling you guys were getting bored, so how about a paint teaser to liven things up?!?

Alex
 
Looks terrible... Wish you had actually put some work into this... Sheesh... :p
 
Alex
What is the max Mach for this one? Did you use ablative? I want to find out how your ablative works out for you.


Sent from my iPhone using Rocketry Forum
 
Wow this thread needs updating. I finished T2T and im now working on the AV bay. Ill post my complete T2T process later.

I mounted my RRC3 and SL100 on the upper sled along with 1 9v battery holder. The other battery holder goes on the lower sled. The wiring is hidden between the two sleds.
image.jpg
image.jpg
image.jpg
image.jpg

Alex
 
This thing's done. I just have to write everything up and do the ejection charge testing.

Heres something. I like to label all my Av bay sleds differently. Heres how i did this one:

image.jpg

Lots of posts coming soon. I need to catch you guys up.

Alex
 
Last edited:
Okay, so maybe not as many posts as I thought. I seem to remember having taken more pictures. I actually did a 20 minute video of the T2T process, but I dont feel like editing it. Working through a 20 minute video in Imovie is torture.

I DO have some photos.
My T2T process is pretty simple. It's the standard 1/3, 2/3, full. The first layer is small. Just enough to cover the middle of the fins and a section of the fillets. This layer is a 90/0. The second layer covers much more area. This spans the length of the fin, almost to the bevel and is a +-45 layer. The final layer covers everything. Again, a 90/0.

Here's a few pics.
DSC00380.jpgDSC00379.jpgDSC00382.jpg

Immediately after all 4 sides, I gave the entire fincan a thick coat of epoxy.
DSC00383.jpg

Alex
 
After that I might have lost count of how many epoxy coats the fincan got. Somewhere between 4 and 7. The fincan was riddles with defects. None structural. Just things like epoxy buildups and such. After numerous epoxy coats and hours of sanding, I felt happy with it.

I needed some kind of protection for my T2T edges. To keep the edges from peeling back from the heat and speed, I gave the tips a coat of JB weld. This is purely experimental. I have seen this done with cotronics but never JB weld. They both have similar TGs so I thought it was worth a shot. If it works. Great. If I get tip delamination, I guess we learned something.
IMG_0485.jpg
IMG_0484.jpg
IMG_0483.jpg
IMG_0486.jpg

Keep in mind this isn't to shield the T2T from the heat. Just to keep it from pulling away from the leading edges.

Alex
 
Onto the pretty part! After coating the fin tips, I sanded everything down and gave it a final coat of epoxy. I do my final coats very different then my thick coats. I apply epoxy by sweeping over the surface with a playing card. This keeps the layer of epoxy thin and smooth.

Here it is before the final coat:
IMG_0496.jpg

After the final coat:
IMG_0499.jpg
IMG_0500.jpg


Alex
 
The final coat got a pass of 400 wet, then 600 wet, then 1500 wet. It's not perfect but It's good enough,

IMG_0510.jpgIMG_0511.jpg

Alex
 
Krylon makes some terrible paints but they make one of the best clear coats around!

IMG_0512.jpgIMG_0513.jpgIMG_0516.jpgIMG_0517.jpg

Alex
 
It's really terrible to find out that you can't draw good flames to save your life after you paint your rocket....

I did this with the bottom and top of the tube. First I drew flames on a piece of paper. That peice of paper was taped to a big sheet of masking tape and I cut the negative out with an exacto knife. Took me a few hours.

This was then wrapped around the tube and painted.
IMG_0503.jpgIMG_0504.jpgIMG_0505.jpg

Alex
 

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