Build - Fire Flyer From Rocketry Warehouse

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DRAGON64

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Today I received my 7/15/2015 Hump Day Happy Hour kit from Rocketry Warehouse. It is a beautiful kit, the fit of each piece is nearly as precise as you can get. I thought I had ordered the kit in "natural' filament wound color, but to my surprise, it was neon green with black. Sadly, I will paint the kit that requires no paint... I ordered the kit with a longer booster (12" longer @ 44"), so as you can imagine, the box was long...

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Another surprise, was how short the 38mm adapter was for the Aeropac motor retention system. SO I will be adapting a 36" long SkyRipper motor with a 6" long adapter... The materials are sound, so I do not expect a problem, but I was half expect a 10" to 12" long motor adapter. Here are the components as they come from Rocketry Warehouse...

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note that there are only 3-fins in the unopened package, and there is a slot machined into it to make the split fin design... very nice work, top quality workmanship.

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I'm off to wash the parts now. They clean for the most part, but just a little gritty.
 
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The MMA is how Aeropak seems to be making them now. I also was surprised a while back on the length of new style adapters. My older ones are much longer.
 
I can see a material savings for Aeropac, and a weight savings for the rocket. I'll just leave the booster open at the other end and maybe add a removable light weight 38mm adapter.
 
Started on the motor mount this evening, mainly getting lines drawn and part orientation... if that makes sense. I like big motors in small airframes, as it makes for cute centering rings. Here are the main components I am working with now:

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The motor tube took a little sanding to get the Aeropac retainer on, after that I was able to get my measurements to place the lower ring. I'm marking that location here with my trusty paper tool guide:

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I measured for fin root and set the upper ring line:

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Those little rings are a little flimsy, but still set perfectly due to the nice close tolerance cut.

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Once confident that the fins were placed, they were set with a little wick of thin CA adhesive. Once cured, I tested the clearance with a fin set.

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Tomorrow I will drill a hole in the middle of each fin slot, to be used for epoxy injection later, and the set the motor mount inside the airframe.
 
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Nice, I got mine earler this week. I was planing to start building this weekend but going watch your build first.
Cheers!
 
Nice, I got mine earler this week. I was planing to start building this weekend but going watch your build first.
Cheers!

Jump in, the build will go quite quickly... to coin an old phrase, it this kit "builds itself"

I am awake and ready to continue on, much work to be done today...
 
Because of the tooling used to cut the fins, a little trimming-to-fit is required. Seen in this image, the leading edge of the fin root has a radius to it...

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Here I am starting the process of removing the radius, which is easily done with a flat file. On the fin pictured I have more to trim to get the right angle I need.

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When done I will have a flush fit against the forward centering ring...

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I have decided not to drill a hole in the fin root at this time, as there is little room left once the motor mount is installed. I will use an alternate route to get epoxy fillets to the internal area of the fins.
 
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I'm now waiting on JB Weld to cure, while I work other projects today. Here is the lower centering ring with a bead. The pencil line is where the Aeropac motor retainer ends. The upper centering ring has the same bead of JB Weld... I have to flip the motor mount like an hour-glass every 20-minutes or so.

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Regarding the Aeropac retainer; it is nearly identical in Diameter to the airframe. I measured my motor mount assembly to leave a slight air gap between the retainer enclosure and the airframe. This will become more clear when I get to that point.
 
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Today I am doing booster prep, prior to mounting the motor mount. I did a little sanding on the centering rings to remove any high spots from the JB Weld beads, and I also sanded the region where the fin roots will seat...

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I also sanded inside the booster tube, and the external where fin fillets will be constructed (sorry for the sun glare)...

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Next, the Aeropac retainer was installed (not permanently), to test the fit of the retainer to booster gap...

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I had mentioned earlier that I anticipated leaving a small gap, between the airframe and the retainer cap, a gap a little smaller than that depicted in the next image...

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But realized that with the retainer flush to the booster tube, the centering rings fit more evenly inside of the fin slots, so here will be the final motor mount configuration when mounted permanently...

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Next we move on to more booster prep.
 
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With the accepted motor mount solution, I could then formulate where I wanted the rail button mounts to be...

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The upper rail button sits 12 3/4" up from the edge of the booster tube. Because we stuffing a 2.1" motor tube in a 2.6" airframe, we leave little room for the screw on the buttons to get a bite-hold. 8/32" threaded inserts do not go in deep enough. But I have a possible solution which I will detail later, once the motor mount install has completed.

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To build internal fillets, the common prep is to drill some access to the fin roots with which to inject epoxy into the root area. Being my first build of a fiberglass kit, I learned real quick what happens when a drill bit is introduced to a slot... the bit grabbed and nearly split the fin slot. The solution was simple; I used a cone shaped stone on my Dremel, and the access holes were bored in seconds...

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I probably will not trim the fibers in the hole, as the can be used to help strengthen the epoxy clay I use to seal the hole...

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I still need to drill the holes for the rail buttons. First I need to finish formulating a game plan for screw mounts that should help to determine the hole size.
 
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Catching up on this thread; I have started work on the opposite end, the nosecone. I ordered a couple bulkheads from Giant Leap Rocketry, and the arrived yesterday. I will be constructing a usable nose bay, a secondary avionics for a tracker, should I ever employ one in this rocket. I suppose that if I launch this rocket a K-class hybrid (6+ second burn) I may need it. Here are the components I will be using for the build...

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The Fire Flyer kit comes with one fiberglass bulkhead, and it is an inner coupler bulkhead. I ordered two plywood bulkheads, that are inner tube bulkheads, to complete the basic design.
 
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The first step was to prep the inside of the nosecone with 60-grit sand paper...

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Along with the nosecone coupler...

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Next I fit the all-thread rod to fit evenly between the coupler ends, then used Blue Thread locker to secure two nuts on either side of the bulkhead...

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The all-thread assembly will be permanently mounted into the nosecone...

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I thought for sure that I had some basic construction epoxy, but I mistaken. I used JB Weld for this portion of the build.

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Once the JB Weld was applied, I slid the coupler in, and then secured the all-thread (centered up) with the ending coupler bulkhead.

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I'll give this a night to cure before installing the U-bolt attachment point.
 
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Minor nosecone update; I drilled out the holes for the U-bolt attachment...

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...and put a final sand on the bulkhead ends for a real nice fit.

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This weekend I hope to get back to the booster, as there is still much to be done with the fins and motor mount.
 
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I was at an impasse on the project, as I was just coming up empty on what to do for the rail button mounts. The marriage between the motor mount and the thin wall airframe left little room for screwing rail buttons to the rocket. My original idea was to drill screw clearance holes, and then using the motor tube as a back stop, inject JB Weld through the holes. With only an 1/8" cavity to work with, the JB Weld would make a nice little expansive plugs that I was going to drill and tap for the button mount screw... There was only a one off chance to make it to work, so I decided to scrap the idea and seek another option. ...Then I found conformal rail guides in my parts box, and WALA! a solution to mounting rail mounts. The conformal mounts fit a 3" tube, yet thye also hug well to the side of the 2.6 airframe. I'll employ the best practices I can read up on for mounting the guide, and can now forge ahead on the project.

With that said, I mounted the motor mount and am ready to start fin attachment this weekend.
 
Everything is looking great, and you are certainly a thorough documenter. I just ordered Wildman's 2.6" DarkStar, which is almost the identical kit. I chose the WM for two reasons. 1) The non-Black Friday price of the FF is way higher than the introductory price of the DS. 2) The DS comes with 1/8" fins, which seemed more reliable to me for the speeds at which this thing will go (mach 2?).

For the rail buttons, you could always use pem nuts. What I do, and I thank One Bad Hawk for this tip, is to mix a little carbon fiber with 30-minute epoxy, dip the rail button screw in Vaseline, screw the button into the pem nut, and then put the epoxy over the back of the pem nut. This forms a rock-hard dome over the pem nut, and then you can take out the screws at will. Allows you to replace buttons if needed down the road.

Now, I say all this having not seen whether or not this is possible with a 2.6" airframe and a 54mm MMT. With my RW X-Celerator, I put one below the botton CR, and one above the top CR.

Here's a pic in case I wasn't clear.

railbutton.JPG
 
Thanks for the tips John, I had considered something similar (not with the threaded insert), but the gap between the motor tube and air frame is tight. With the motor tube at the way to the end of the airframe, working a threaded insert into the gap would be tough. The booster I have is a special order (extended by 12" to 44"), and reaching just in front of the motor mount to put in an insert would have been near impossible... I say near, as I am sure there is a way, but not happening with this particular kit. I looked at the threaded PEM style inserts that I have, and the "bite" teeth on the insert are longer than the tube is thick. Thin wall fiberglass tubing is not without it's own minor challenges.

Good luck with you 2.6 Dark Star. That is a sexy kit in any diameter, and you are right, that pricing is quite nice for what you get. Definitely looking forward to a build thread from you on that kit.
 
So last night I mounted the motor mount into the booster. The area for the front centering ring was sanded, to help with the JB Weld adhesion, bu taping a broad flexible nail file to an all-thread rod. Most anything would work, as long as I could reach deep enough, yet still apply the pressure required for the grit to bite into the internal wall of the airframe. Sorry no pics of the cobbled-together sanding tool. However, I made a similar tool using a wood dowel and a hobby Popsicle stick... crude as it was, it worked as intended.

dJXDNSc.jpg


Not my best "smear job" as indicated by the dark areas on the lead centering ring, but the outcome was successful... another reason why this rocket will get paint. Today I used a syringe to inject JB Weld onto the back centering ring, and then the slurry was spread evenly, and the motor retainer was installed.

GNjgqIF.jpg


I did not too terrible amount of epoxy at either centering ring, as the through the wall fins will ensure that the mount is going to stay put. The fins will get mounted this weekend.

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I got a late start, but I did manage some progress. First off, I tried making one of the fin alignment guides using foam core board... I guess there is an art to it. With a little more practice I'll get better. Here are the basic tools used , along with the roughed up finished guide.

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No turning back, I collected the tools needed to mount the first split fin: Syringe; popcicle stick, sand paper; JD Weld and the fin guide...

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So the first split fin was sanded at he root end on both sides. I sanded enough to ensure that the finishing fillets would have adequate roughness to adhere to...

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I have come to like JB Weld; The epoxy is quite viscous; stays where you put it, and has great work time. Here, the epoxy is mixed (pretty, right?)...

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...and then loaded into the syringe (6cc)...

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The slurry was then injected into the fin slot...

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The epoxy flowed well into the slot, but at times I moved to slow or too fast... the bead got kind of uneven at times...

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There was just enough left to touch on the leading 1+ inches of the fin that rides on the outside of the air frame...

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The fin slid right in with zero mess...

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Since the fin slot is carved into the fin, instead of having two fins, I ran into an issue. The center link on the fin slot kept bulging back out of the fin slot. I would push it with my thumb, but once released, the center would bulge back out of the slot...

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I ultimately ended up taping the center portion of the fin down while the epxoy cured...

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I added the fin guide, and let the epoxy cure the rest of the afternoon. Notice the center portion of the fins pushing back against the tape. I checked about every hour or so, to press the center down... it finally stayed.

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I still have two more sets to install, and the fins will be ready for fillets...
 
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The fins have been mounted, and are ready for fillets. Here I have dry fit the remaining airframe components and posed the rocket with largest possible motor I could fly in it. The motor is a 54mm SkyRipper Systems K-class motor, and stands nearly 36" long...

d6FHRnG.jpg


So, at this point I am questioning the decision to elongate the booster from 32 to 44 inches. Is it me, or are the fins looking kind of small? I have been unable to use my RocSim since buying a new computer. I'm working with Apogee Components to try and get the issue resolved. So, if anyone has this rocket in RocSim, maybe you elongate the booster by 12" and let me know your thoughts on the fin size to rocket length ratio. I sure do not want to introduce "coning" to a flight profile.
 
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The fins have been mounted, and are ready for fillets. Here I have dry fit the remaining airframe components and posed the rocket with largest possible motor I could fly in it. The motor is a 54mm SkyRipper Systems K-class motor, and stands nearly 36" long...

IMG_8841_zpsiu2j8xk1.jpg


So, at this point I am questioning the decision to elongate the booster from 32 to 44 inches. Is it me, or are the fins looking kind of small? I have been unable to use my RocSim since buying a new computer. I'm working with Apogee Components to try and get the issue resolved. So, if anyone has this rocket in RocSim, maybe you elongate the booster by 12" and let me know your thoughts on the fin size to rocket length ratio. I sure do not want to introduce "coning" to a flight profile.

If you can shave some length I would do it. It does look too long.
 
One of the many key features of a hybrid vehicle is the length of the booster to accommodate the longer motor components. In the SkyRipper line-up I also have the 36" by 38mm J144 motor. When I ordered the kit from Rocketry Warehouse, I asked that it be able to cover my full line of hybrid possibilities. The more I look at the rocket, the more I believe I will be okay... I just need to get my RocSim running so I can run some sims.
 
If I get a sec, I could use my sim for the DarkStar 2.6 and add 12" and see what happens. But keep in mind that adding length moves the CG forward, adding stability. The CP will move forward a bit, too, but my guess is that you're okay.
 
Started the first set of fillets today, which I found I am quire rusty at. Once the fillets were starting to set, I laid out where I wanted the rail guides to mount and then began to manicure the airframe and Conformal rail guides with a Dremel tool...

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The manicure consisted of groves and dimples machined into the airframe (outline of rail guide), as well as the bottom of the rail guide. Again, JB Weld was used for the adhesion.

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It is to bad that JB Weld is so expensive, because it is real nice to work with, here is the last rail guide, mounted 18" in front of the lower guide...

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The rest of the fillets should go smoother, after which I will start on the avionics.
 
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If I get a sec, I could use my sim for the DarkStar 2.6 and add 12" and see what happens. But keep in mind that adding length moves the CG forward, adding stability. The CP will move forward a bit, too, but my guess is that you're okay.

That would be much appreciated, thank you for offering.
 
I stretched out my screech. With a K350 I get 2.23 caliber of stability. I dont have any hybrid files loaded or I'd check those too.

I think you'll be fine as long as your thrust isn't too low.
 
Johnny, if you have a Menards nearby you need to roam the after-Christmas clearance aisle. Two years running I've been able to pick up the large 10oz "industrial" kits for like $8 each.

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I stretched out my screech. With a K350 I get 2.23 caliber of stability. I dont have any hybrid files loaded or I'd check those too.

I think you'll be fine as long as your thrust isn't too low.

SkyRipper motors were always nice "rippers" for lack of a better term, so I do not believe low thrust will be an issue. Worst case, I tape off one side of each fin set, and fill the slot between the finds with JB Weld and make more surface area...Just kidding. I think I will be alright also. seeing the rocket all in one with the fins on really got me guessing.

I like Rocket Poxy its a lot like using JB Weld. Give it a try.

Wildman has this in the larger sizes, I may have to give it a go on the next fiberglass kit.

Johnny, if you have a Menards nearby you need to roam the after-Christmas clearance aisle. Two years running I've been able to pick up the large 10oz "industrial" kits for like $8 each.

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First I have seen the economy size JB Weld kits... I may have to get you to pick some up for me... we do not have a local Menards. $8 is a good price for 5X the amount of epoxy.
 
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