Redshift- 38mm Minimum Diameter Rocket

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nute

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Well, It's my turn to do a 38mm minimum D. I'm going with the name Redshift



redshift pic 2.jpg

The basis of this rocket is a Wildman Intimidator Mini. The stock kit has a 22" long, thinwall, 38mm airframe, and one of the new polycarbonate nosecones. There are 3 G10 fins, that I measured at 1/16", perhaps slightly more, thick. It has a 29mm motor mount, and the centering rings to match, but we won't be needing any of those ;). They have tabs that extend to the motor tube, which will also have to go :).


The other part of this rocket is a Wildman "mini" Dual Deploy Upgrade featuring a 4" coupler, and an 8" section of tubing. Mine also came with the famous (or infamous) stepped aluminum bulkplates. I'll be using this for a standard Dual-deploy setup, with the drogue (more on that later) in the booster section, above the motor, and the main in this payload section.

This will be my first real High Performance rocket, so I'll probably be taking it a bit slowly. I'm planning to fly it mostly at my home club here in New Jersey, The wonderful RadRocketeers. If I make it to LDRS, It'll probably fly on something big to 8K+. Maybe an I600R, or a 38/1080 J if I can get someone to fly it who's L2. We'll see.

I'm open to suggestions and ideas, I haven't done anything like this before.

Parts/ Pics:20141230_175944.jpgThis is everything that came with the kit, plus what came with the Dual Deploy upgrade. I obviously won't be using the motor mount, and will have to add some stuff along the way.

20141230_180826.jpg
Dry Fit of the rocket + the Dual Deploy upgrade. This is a nice looking rocket!​

20141230_180056.jpg
These fins are unlike any I've ever seen before. They have a pattern on them that's almost reminiscent of carbon fiber. It was on all of the kits I got from Wildman this year, no complaints here, at least visually.​



20141230_180138.jpg
Stepped aluminum bulkplates​


20141229_182704.jpg
Parts being washed off- this is a couple of kits jumbled together for washing, but this one's in there :)


20141230_180913.jpg
Aluminum bulkplates and the coupler. It's gonna be a tight fit to get everything in there.​


Recovery:
As far as recovery goes, this rocket will be pretty standard. Like I said, I'll have standard Dual Deploy. For a drogue, I'll probably use a mylar streamer, likely about 6" X 36". I'm considering investing in a TFR 4 X 40, or a 6 X 60 thin mill streamer. This would take up a bit more space, but be more reliable and provide a more repeatable descent rate. In larger sizes of mylar, especially when packed in small spaces, I have seen severe burning of the streamer, tearing apart during descent, and failure to unfurl. I probably could drop this drogueless, but if at all possible, I prefer to have some sort of drogue device.

The main will be a TFR parachute, probably 15" or 18", depending on final weight. I have had very good success with these parachutes before, and the thin mill chutes pack tighter than any other nylon I've seen. I have a thin mill and regular 15", and one or two 18".

20141230_191744.jpg
Various parachute options.


The brains will be an RRC2+ in the altimeter bay. I have a 100% success rate with mine over the course of 6 or 7 flights. I'll be using one of the 3D printed altimeter sleds available through Missileworks.
RRC2+LiFront.jpg
I'll also be using the switch pictured here, the 110/220 voltage selector. I hear good things about it, and It hasn't failed me on my Darkstar Lite DD.
I'm planning to use the Li-Ion battery suggested with this sled, the Sparkfun 400MaH "Polymer Lithium Ion" battery.
I ordered the sled today, so I'll be able to start working on the AV-bay soon. I'll be using .5g charge wells from Doghouse Rocketry. The 1.5g version hasn't failed me yet, and I've only had the best of experiences with Bill and his products. I'm still working on the bulkhead layout. I'm planning to use an eye-bolt to attach recovery gear to, but the standard 1/4" ones I have on hand seem to simply be too big for this application. I'll also have to fit the nuts from the allthread, and a wire connection of one type or another. It's looking like a terminal block will be off the table completely, except for maybe one of the elevator terminals available from Missileworks, which seem to be notably smaller. However, I'm considering going with a simple e-match pass through. KISS, right? Maybe, if I have time, I'll see if I can't add a bulkhead sealing Well-Nut to my order with Missileworks.

As far as tracking goes, this rocket will definitely have it. I'm planning to get a BRB RF tracker in the near future, and I'm thinking I'll use the "tape it to the shock cord" method, as there's really no room in the E-bay, and without a threaded tip in the NC, It'd be tricky to do something akin to one of Mr. Crazy Jim's glueless nosecone AV-bays.

Bonding and Fin Attachment:

The vast majority of , if not all, bonding will be done with Rocketpoxy G5000. I picked some up on Wildman's sale with all the colored dies. I'm thinking I'll just go with black, but I'm tossing around the idea of using yellow. Anywho... I've had excellent success with Rocketpoxy before. I haven't had any "extreme" flights per say, but it held the fins on an Argent on it's way to 3500 ft, hitting 600mph, and kept everything intact when my ShapeShifter Mini came in ballistic from 1500 or so. I have plenty of faith in it.

The fins will have the tabs sanded down to the thickness of the body tube, and then will be glued in place. I'll have a 38/720 case in the rocket wrapped in wax paper or parchment paper (any suggestions on which works better?) to prevent drips, and to keep the fins in place. I'll probably keep them in alignment with a guide from Payloadbay.com. Then, I'll pull large fillets using Rocketpoxy and a dowel dipped in rubbing alcohol. This technique has also served me well before.

Launching:

I'm still deciding if I'll put rail guides on this thing. I think someone at our club might have a tower, but I'll have to be in contact with him, and there'll probably be a tower somewhere at LDRS, so maybe I can go for tower launching and really get every foot out of it. If I do use rail guides, I'll go for conformal rail guides.

Motor Retention:

The plan is currently to use plain old friction fit. I'm thinking about an Aeropack minimum diameter retainer, but I don't like the idea of having a limit on the largest motor I can use, and also having to deal with extensions of the threaded rod, etc. I'm also not keen on missing out on motor backup. Granted, some motors won't be able to use the motor backup regardless, but it's an option I like to have.

Shock Cord Attachment:

I'm thinking of doing something similar to what Wildman recommends in their instructions for their BH 24. A short piece of coupler with the kevlar bonded to that. I'm open to suggestion on this, as it's something I'm still pondering.

Finish:
I'm gonna go with the straight black fiberglass- maybe give it a clear coat. The nosecone will be bright red, courtesy of Rostoleum, and the fin tips will be bright yellow, also from Rustoleum. I'll add a silver tip, because, well just because. The decal will be from Mark at Stickershock. I'm still working out some of the details of it, but I'm sure It'll turn out wonderful.

That should just about cover most of it, I'm sure there's some stuff I forgot though. :)
 
I like the name.

Aside: best bumper sticker I ever saw was red and said "If this appears blue you are driving too fast"
 
I like the name.

Aside: best bumper sticker I ever saw was red and said "If this appears blue you are driving too fast"

Thanks :)

LOL, that's great.

On a related note: objects_in_mirror.png
"Objects in Mirror are Bluer Than Thy Appear"
 
Awesome!!!!! Definitely subscribed. Really hoping you can make it out I LDRS :)
 
Thanks guys! :)

I'll put up an OR file once I get a chance to weigh the parts I have.

Nate
 
Is very nice, it is.

I really like the graphics/color scheme - nicely done.

Since you are lengthening the rocket (via the dual deploy payload section), and adding mass towards the pointy end (AV bay/avionics/tracker), you might want to consider trimming those fins down a bit - something sleeker, faster, more stream-lined. Dink around with your sim software to find what will work best.

NO rail guides! Build or borrow a tower launcher. This is a minimum diameter high flier, yes? Then it don't need no stinking rail buttons/guides sticking out the sides - again think sleek and streamlined.

Do not use those big honking 1/4" eyebolts - WAY to big and heavy for something like this. Consider going with a kevlar loop instead - much more compact (for that limited real estate you have on the bulkplate), lighter, and every bit as strong as the cord you are attaching to it, right?

Yeah, that finstock is pretty cool ain't it? I grabbed a couple of WildmanSports a ways back and they came with the same stuff. I like it.

And yes, I like the aluminum bulk plates! (how about that?)

I'm excited to see this rocket created - can't wait to hear about it's flight(s). Best of luck with it.
s6
 
I believe it was wfcook who designed the 3d printed fly away rail guides that could also work. They detach after the rocket leaves the rail.
 
Is very nice, it is.

I really like the graphics/color scheme - nicely done.

Thanks :)

Since you are lengthening the rocket (via the dual deploy payload section), and adding mass towards the pointy end (AV bay/avionics/tracker), you might want to consider trimming those fins down a bit - something sleeker, faster, more stream-lined. Dink around with your sim software to find what will work best.

You know, after drawing it up, and especially after doing some dry fits, it did look like the fins were a bit large- almost to the point of too large for the rocket. I'll do some playing around. I'm curious as to how heavy the av bay will turn out- it's gotta add a couple ounces, at least.

NO rail guides! Build or borrow a tower launcher. This is a minimum diameter high flier, yes? Then it don't need no stinking rail buttons/guides sticking out the sides - again think sleek and streamlined.

LOL, yes, a minimum diameter high flyer this is. Like I said, I'll have to look into borrowing a tower. It would definitely be a great advantage and lots of fun to boot!

Do not use those big honking 1/4" eyebolts - WAY to big and heavy for something like this. Consider going with a kevlar loop instead - much more compact (for that limited real estate you have on the bulkplate), lighter, and every bit as strong as the cord you are attaching to it, right?

Yeah, definitely NOT using those eye-bolts. I was looking around at what I had, and nothing seemed to be a good size. I like the idea of a kevlar loop. Is the idea just to loop it through a hole and tie a knot inside the AV-bay so it can't pull through? Or use two holes, and create something like a kevlar U bolt?
Thanks for the suggestions!

Yeah, that finstock is pretty cool ain't it? I grabbed a couple of WildmanSports a ways back and they came with the same stuff. I like it.

Yes, definitely cool, I'll try to keep these fins clean during the build, that's an awful nice finish right there!

And yes, I like the aluminum bulk plates! (how about that?)

I like them too :), they definitely add a cool factor.

I'm excited to see this rocket created - can't wait to hear about it's flight(s). Best of luck with it.
s6


Also, does anyone have a weight for their 38mm av-bays? I'm honestly not that good at estimating, lol.

I'm figuring, if I were to cut down the fins, the resulting forward CP shift could be a problem on larger motors. Adding wight to the av-bay (in the form of the altimeter, battery, etc.) would help this, but it's hard (at least for me) to judge how much without an accurate weight.
 
Nate,

Awesome rocket! I am hoping to go to LDRS this year (It's going to be at URRG right?) to fly a couple minimum diameter rockets as I should have my L2 by then, so there is a pretty good chance I will be there with my tower. It's fully adjustable for diameter and has about 6 feet of guidance.

Can't wait to see this fly!

Coleman
 
Nate I think wfcook designed some 3d printed fly away rail guides that detach from the rocket after it leaves the rail so that's another option.
 
I will be watching! After I get my MD rocket build.... I think we should all have a drag race at LDRS.
 
I'm planning to fly it mostly at my home club here in New Jersey, The wonderful RadRocketeers. If I make it to LDRS, It'll probably fly on something big to 8K+. Maybe an I600R, or a 38/1080 J if I can get someone to fly it who's L2. We'll see.

Consider another build of a low-flying rocket to get your L2 at your home field, then go for your moon shot 38mm MD at LDRS with your very own J motor.
 
Consider another build of a low-flying rocket to get your L2 at your home field, then go for your moon shot 38mm MD at LDRS with your very own J motor.

We are JR's. We can't cert L2. We can fly up to our mentors level though. This is how a couple of us JR's are flying a M at LDRS.
 
Consider another build of a low-flying rocket to get your L2 at your home field, then go for your moon shot 38mm MD at LDRS with your very own J motor.

I wouldn't be flying for my cert. My mentor, or something to a similar effect would be basically flying it for me on a J. Since I'm under 18, I can't get my L2 yet.
When it does come time for my cert, though, that's the plan. A non-extreme rocket at my home field.

Nate
 
Alright, here's a fairly accurate sim file:

View attachment Redshift Accurate Model for Upload.ork


Regarding trimming the fins:

I'm hesitant to do any major reshaping, as I'm just not that confident cutting the fins. I would probably be using a belt sander to just sand down the height. So, trimming down the top of the fins yields a fin that is shorter, but that I'm not aesthetically fond of. The other option is to sand down the bottom of the fin, yielding a nicer shape, but then I have a shorter root cord, and fin slots that are longer than the new root cord.
Does anyone have suggestions or input about that option?

That said, at this point, I'm leaning towards not modifying the fins. The goal of this rocket isn't necessarily to eek out every foot of altitude, and the gains from changing the fins on a J570 is only about 600 ft.

Nate
 
Nice build. I too am starting my first MD, 38mm Blackhawk. Where can these printed fly-away rail guides be obtained?
 
I say if your going to make them smaller cut them out but when cutting keep a distance of about and 1/8" from the new size the. Use a belt sanded to get hem to the rift size if your not comfortable cutting them directly to the right size.
 
I say if your going to make them smaller cut them out but when cutting keep a distance of about and 1/8" from the new size the. Use a belt sanded to get hem to the rift size if your not comfortable cutting them directly to the right size.

That's a good idea. My dad is getting home later today, so I'll consult with him. He's the one who really knows his way around a table saw (and radial arm saw, and jig saw, etc.)


I got the first fin tab sanded off today. There's just a little bit of the tab left which is just the thickness of the wall. I might take it down a little more, but it's a very good fit, and the fillet will hide any little discrepancies:


20141231_124841.jpg
Regular fin compared to the sanded fin (top)

Nate
 
That's a good idea. My dad is getting home later today, so I'll consult with him. He's the one who really knows his way around a table saw (and radial arm saw, and jig saw, etc.)


I got the first fin tab sanded off today. There's just a little bit of the tab left which is just the thickness of the wall. I might take it down a little more, but it's a very good fit, and the fillet will hide any little discrepancies:


View attachment 250303
Regular fin compared to the sanded fin (top)

Nate



Wait no band saw? Now I see why it would be difficult.
 
Wait no band saw? Now I see why it would be difficult.

Yeah, we do have a band saw. Do you think that would work best? Other than some tubing once, I've never cut composites. AFAIK, the only blade we have for that is a wood blade. Again, my dad will know how well it'll work. Maybe if I decide to cut the fins, I can practice on the fin guides from my BH24 first.

Nate
 
do not clear coat the fiberglass. I clear coated my darkstar mini and it completely hides the look of the glass. It is just gloss black. also, it doesn't bond well to the fiberglass so it scratches easily. once I did it I was told by several members of the club not to. oh well. one vendor suggested putting Armor all or clear shoe polish on raw fiberglass as the very last step, after decals. I will try that on my next build.
 
Yeah, we do have a band saw. Do you think that would work best? Other than some tubing once, I've never cut composites. AFAIK, the only blade we have for that is a wood blade. Again, my dad will know how well it'll work. Maybe if I decide to cut the fins, I can practice on the fin guides from my BH24 first.

Nate

Ya the band saw would be the easiest to work with. You're probably not supposed to but I've been cutting composites on my band saw with the wood blade.
 
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Ya the band saw would be the easiest to work with. You're probably not supposed to but I've been cutting composites on my band saw with the wood blade.


Okay, I gotcha, I'll see how much I might be able to get done before I have to go back to school.
Thanks!
Nate
 
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Nate I think wfcook designed some 3d printed fly away rail guides that detach from the rocket after it leaves the rail so that's another option.

Well the initial design sort of, um...sucked. But I have recently printed a dramatic improvement after getting acccess to a 3D printer andd being able to play with the design to get something working. Nate send me your address by PM and I'll send a set to you. They currently come in a lovely shade of Magenta by virtue of the fact that it was the cheapest color.
 
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