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Discussion in 'High Power Rocketry (HPR)' started by Valkyrie, Jul 9, 2017.
Nice work on the slideshow too.
Thanks for posting the video. Top marks for the Filter soundtrack. Nice Shot.
Unbelievably straight flights with virtually no roll at all.
Now I'm anxious to start working on my Screech 2.6.
Thanks guys. I can't believe it's been two years since I popped those four flights off. I need to get to work on something cool again.
More progress. I made a jig from cardboard and installed the fins. I filleted the fin roots to the motor tube as well as to the inside of the BT. Overkill? I figured why not, its certainly not gonna hurt and is a very small amount of weight. It was tedious and I was able to get them done with a minimal amount of mess. I did the external fillets on one fin. using the tape method, I dyed the epoxy with graphite to help see what I was doing and to show any spots where there was an imperfection. I used a piece of PVC tubing to mark and then pull the epoxy smooth. It worked very well. I have two more fins to do. The aft CR is installed also. I'm gonna skim coat it with JB weld and instead of a pair if circumferencing fillets there just mix enough to do everything and be done with it and install the motor retainer.
Out of curiosity, How fast and how high can this rocket fly successfully? Generally?
If you put a Loki K motor in there- very high and very fast . Depends on how you built it.
I out another fillet on the fins this evening. Its tedious and I do one at a time. Three more to go!
Starting to think that it will be done by the end of the week, minus paint? Much faster to build than I anticipated. I am looking through the recovery gear that I got with it a small drogue and a 30" main. I am thinking of using a 4' main? With a chute release I can set my altitude pretty easily for main deploy and I see that many rockets that get beat up under the stock chutes on landing? Why not slow it down a little more if I have a good handle on the deployment altitude? I'm way ahead of myself but I'm just thinking.
I have a lot to work on. Paint is gonna be tough. I don't want to use rattle can paint on it, I'm thinking of a simple spray gun and automotive paint. I want to go with heavy flake candy apple red. The entire rocket one color and maybe an accent on the switch band of the AV bay.
Also, I'm going with SS machine screws to hold the NC and forward bay together in case I ever make it a true DD. What size and type screws would you recommend? Should I use anchors on the back side? This thing is pretty cool looking. Tall and looks fast too but my experience with anything bigger than 29mm E and F motors is about it.
Does anyone have a .ORK file for this I can tinker with? I don't know much about using this program and starting from scratch seems impossible.
I don't have an ork for that rocket, but I can give a couple pointers
The cool thing is, you Don't have to get every single component in place. Just make the externals the correct size (Nose, tube, fins), then put an internal tube in, set it as motor mount, and you're done with construction.
Place (n) parachutes in there set to open according to your flight plan. You're done with components! (Although it's hard to model a chute release flight)
Then in the parts list click Sustainer, and go to Override CG. You'll weigh and balance your model and just make your simulation match.
Last thing is the surface finish which will be unique to your rocket anyway. Then it's off to the simulations! (Make sure your ground level altitude is set for where you launch. I forgot to change mine for awhile when I moved from a river Delta (~97') to Hill/plain country (~900')
If it were my bird I would use M3 countersunk screws, with some sort of insert inside, rather than just tapped into the f/g tube. An alternative might be to add some more f/g to thicken up the airframe where the threaded holes need to go and tap them out. I assume you are in the USA so there might be some imperial screws that are more available for you, and a slightly coarser thread than the M3 has would possibly be an improvement.
I have used pan head screws in the past but the CSK ones look better.
If you are countersinking the f/g tube it can come out a bit out of round (typically triangular if you are using a drill for countersinking) if you don't have a tool that has a slightly negative rake on the cutting edge. An alternative to finding such a tool is to put a few layers of cloth (old t-shirt or similar) between the workpiece and bit. It has the effect of making the hole nice and round. Drill slowly so it doesn't bite in and ruin the tubing, especially if you are using a standard drill.
And the fins are done and the fillets are nice! I also put the aft CR in and used JB weld as the aft epoxy since I figure this is a high heat area.
The fins are filleted to the motor tube as well as interior of the BT and the exterior.
Not sure whats next.
K1127, J510, K1127, j1026
all around 9,000 feet and Mach 1.2ish
Well the hard stuff is done. I feel pretty confident that the motor mount and fins are as well constructed as they can be. I'm gonna mount the motor retainer later this afternoon. It's an Aerotech screw on style.
Any recommendations on son a decent altimeter to record flight data? I was thinking the Altimeter Three from Jolly Logic? I'm going to makr and drill the rail button mounting holes also this weekend.
The JL A3 is pretty sweet. Very versatile, and I love the Bluetooth connectivity.
Let's see some pictures!!
Aeropack was the first, but Aerotech does sell retainers under their name:
the Jl3 is nice for recording and ease of use. However, you could get an altimeter capable of doing deployments as well, and what I feel are better graphs of flight data for less money with an RRC3 or SLCF
Yep it's Aeropack, lol. Anyway. I have some pictures but they will not upload. Any ideas?
Here's the fins and everything but the retainer[/IMG]
Here she the motor tube with the Kevlar recovery harness in place with JB weld.
Thanks. Not sure what is next. I need to get the launch button holes located and drilled but I am thinking that the tube is pretty thin and that building up the area and tapping the holes out is the way to go. I was thinking a piece of radiused glass epoxied to the outside of the tube at the button locations and then and tapped for the button screws? And where would I get a small piece of glass that would match the outside radius?
You could get an av bay band and cut it up. It's not a terrible idea
i just drilled holes slightly smaller than my screws, filled it with epoxy, and then screwed the buttons in. No additional reinforcement I've done almost everything else I build that way, and it seems to work. Haven't ripped one off yet. There's typically not a lot of force on the buttons.
Oh yeah! I completely forgot about those. Oops.
Ditto David's plan. I even leave out the epoxy and have never had a button failure.
What would be a good sized motor case for this rocket?
I'd use a CTI 38/3-grain all day long, or an AT 38/360.
Those are all L1 motors though. But with this build, it'll be easy to get your L1.
Also, if you get the spacers (CTI) or the RAS (AT, spacers), you'll be able to fly it on smaller motors in that case.
I'm trying to think of every possible way to make this a solid model that will function. I don't want to leave anything to chance.
Yeah. 360 or 3-grain gives you a great range of motors to fly at a great price. You can really punch it with some of the high thrust motors or go easy with some softer motors. After you've been flying it for awhile, you can get a larger case too really kick it, but the 3-grain size is a great value every way around. Definitely check what your local dealer carries to decide between AT or CTI.
I'm getting to the finish line on air frame construction. I used three #8 1/2" sheet metal screws to secure the forward tube to the AV bay and I'm gonna do the same to attach the nose cone to that should I ever want to try DD. Turns out that the fin slots aren't exactly 120 degrees apart, I used the slots to mark where I would drill holes in the rest of the body by transferring them to the AV bay and then to the body tubes. Its only slight and not able to be seen, just that the holes only line up one way. Not a big deal. Once I'm finished with this part, I have to decide on shear pins or friction fit and rig the recovery harness assembly.
Otherwise, its done! I feathered out the fin fillets with some 400 sand paper. I also put together a model in OR though, I don't know if its accurate or not.
While I am thinking about the recovery set up I ordered a 48" main chute. I plan on using the 12" drogue chute that was included also. I am not sure how to actually rig everything though? The kit came with two lengths of 1/2" tubular nylon. I epoxied a Kevlar harness loop to the motor tube that terminates about an inch or so from the end of the BT.
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