My LOC IV Build Thread

Discussion in 'Techniques' started by Curtis Enlow, Apr 15, 2019.

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  1. Apr 15, 2019 #1

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    I always enjoy reading build threads and always learn a lot, so I thought I might share my IV build journey here.

    This is my first rocket in some time, since my step-son & I built and flew rockets (and I won't tell you how old he is now, but 'D' engines were monsters then), but I have kept my hand in building stuff ever since, including radial aircraft engines, jet airliners, restoring a wooden sailboat, R/C planes and dabbling in electronics. So it will be fun to bring a lot of those things together in one of my favorite things ever - Rockets!

    I am mostly here to glean from the tremendous knowledge base here. I have not only been warmly welcomed, but also the generous recipient of some great advice already. I can only hope that some things I do here might inspire or help someone of my own skill level, and that I might even share something new to the more experienced members.

    ~

    First, a lot of research showed the IV's fins to be a weak part of the rocket; it seems they don't make great landing gear. So I decided, after watching John Coker's video on vacuum bagging fins, to mod the IV's fins to a simple symmetrical airfoil with tapered balsa skins and some 2oz glass and epoxy. I feel there are some aerodynamic advantages for airfoil fins on slow rockets at the price of a small amount of weight (51g vs. 31g stock, per fin) and a little added drag, plus it's fun to do :)

    Something I did different was to leave just a little edge on the leading and trailing edges and finish the sanding to a point after bonding to the ply core (but before glassing) so they would have support and wouldn't fray or split, plus it resulted in a little more of a precise edge. I also added some 3mm Plastruct styrene triangle stock to the leading & trailing edges, as I didn't feel I would have been able to hand-sand them as precisely. I think they turned out nice.

    [​IMG]

    [​IMG]

    [​IMG]

    While those were curing I tested two new, unflown MissileWorks RRC2-Minis I found (for a pittance!) in a Foodsaver canister with a 60mL horse syringe and a bit of aquarium tubing. (I plan on adding a BT tube extension and a coupler electronics bay for a HP/Dual-deploy Super IV at a later date). Without an altimeter it's not precise, but at least I know the apogee event is accurate and the main fires about where it should by releasing the seal button and feeding the syringe back in to the canister. There are methods out there (for those who know & enjoy enjoy the strange little shapes & letters on their calculators and how to use them) to actually calibrate the mL's on the syringe and capacity of the canister into altitude, but...well, this works for me. At least for now. (I think I will pick up a keychain-style altimeter soon; they seem handy)

    [​IMG]

    I laid out the locations of the bulkheads, rail lugs and motor retainer on the BT for reference and upgraded the shock cord hardware (the pre-cut hole is 1/4" but the supplied hardware was 1/8"?).

    [​IMG]

    [​IMG]

    Luckily, this is about when I discovered that my forearm is too big to reach the shock cord eye-bolt on the forward bulkhead in the 4" tube(!) So, not wanting to have to search for someone to reach in to attach and disconnect the shock cord I made an extension and sewed the loop with a Speedy Stitcher clone (BTW, Harbor Freight carries a stitching awl that is cosmetically & functionally the exact same tool for $6.49. I'm just sayin'... (A smaller needle can be had on the popular auction site for very little).

    [​IMG]

    ~

    Next up, I need to epoxy in the MMT/Fwd/Mid-bulkhead assembly into the BT. I had someone rip a 45ยบ on a 2X4 to make a fin locating jig, so I will be making that, as well as a cradle to hold the beast after the fins are on.

    Again, per John Coker's suggestion I will fit but not epoxy in the aft bulkhead until I have applied internal fillets to the fins where they contact structure. (If you're new and haven't watched John's YouTube channel, you should: https://www.youtube.com/user/JohnLCoker Lots of good stuff to be found there.

    Suggestions & advice are always welcomed!

    C
     
    Last edited: Apr 15, 2019
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  2. Apr 17, 2019 #2

    Curtis Enlow

    Curtis Enlow

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    Built a 'V'-style fin alignment jig along with appropriate spacers for my fins. I really like the guillotine-style jigs and I hear they work great. that is something I might need to tackle before a new project. If anyone knows of plans that exist for one somewhere i would appreciate learning where.

    [​IMG]

    It's one thing to talk about weight reduction by cautious use of epoxy. It's an altogether different thing when you are painting it in with a two-foot long stick... I used milled glass fibers to give it some extra strength and to thicken it up a bit so it doesn't run or flow as much. But, the motor mount tube is now in, so it looks like fin to body tube assembly day tomorrow.

    [​IMG]

    Also, the 29mm & 38mm RMS/RAS kits should come tomorrow, so that's exciting. I have a 38mm RAS and a 38mm 120 & 720 Case which should allow use of small 'G's up to 'J', as well as a 29mm RAS and 29mm 180 and 360 cases, which should give a lot of flexibility and access to haz-free reloads.

    I need to make a cradle that will work for both the standard IV as well as the planned HP/dual-deploy Super IV with an extended BT & electronics bay coupler. I am thinking building it in such a way as to serve as transport protection might be smart, perhaps with some sort of fence to protect the fins. I have to pull the sailboat project out of the garage to use the band saw, so I hope it stops raining...
     
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  3. Apr 18, 2019 #3

    Curtis Enlow

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    So, there are things I like about the 'V' type alignment jigs, and some things I don't: I like their simplicity, they are easy to build and easy to store. But, by it's nature, the fin is pointing down (unless you raise it up somehow or clamp it to the edge of a bench) and that makes it difficult & awkward to insure its placed properly before you clamp it. The second thing is that, by stretching rubber bands around the body tube to hold it down to the 'V', it imparts a twist to the tube and tends to pull it out of radial alignment with the fin, and that's a major pain. I think the guillotine jig probably is much easier to work with. Next time.

    At any rate I got the fins tacked into place and then all the joints painted with thin penetrating epoxy. A few hours later when it had set up but was still chemically active, I mixed up a thickened, gap filling batch and coated the internal joints and along the external fin root.

    [​IMG]

    Then I almost screwed up. No, let's be honest, I did screw up. Getting all excited because the tube was starting to look like a rocket I went ahead and epoxied in the aft bulkhead and sealed it with thin epoxy. While clearing bench space to set it down I noticed my rail buttons with their ply backing plates on the bench (one of which was supposed to go just forward of the aft bulkhead. The aft bulkhead I just epoxied in a bit ago.

    Crap.

    Luckily, the epoxy was at gel stage and after drilling two small holes and screwing in two wood screws I was able to pull it out. That was a stupid mistake. I've now got some additional sanding to do.

    So, it's all finned now. I still have a little more work to do before adding fillets - another coat of thickened epoxy at the fin roots before fillets, but it is starting to look like a rocket :)

    [​IMG]

    The good thing that happened was the motor hardware - 29mm & 38mm RAS and assorted 29mm & 38mm cases arrived today, so I am set there. I enjoyed fitting the pieces and screwing the closures in (have I mentioned that I am easily entertained?). This should allow a lot of future flexibility, not to mention cost-savings, in the future.

    [​IMG]

    Time willing, I will get the cradle for the rocket cut, drilled and put together tomorrow, but at some point I need to be a grown-up adult and attend to household stuff.

    Dang it.
     
  4. Apr 18, 2019 #4

    Rex R

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    there is a downside to the 38mm ras, the charge well cap (included with the reloads is a bit larger than the charge well on the floating forward closure. you will need to use masking tape to either hold the cap in place or skip the cap and just use the tape to everything in place. I use tape in a cruciform pattern with a 3rd piece to hold the 1st two pieces in place, that has worked so far.
    Rex
     
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  5. Apr 18, 2019 #5

    Curtis Enlow

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    Thanks, Rex. I have heard that about the RAS system, including the tape dots they supply being...inappropriate to the task. Do you tamp down the charge with wadding and then tape it? Or is the charge loose in the well?
     
  6. Apr 18, 2019 #6

    Rex R

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    I generally use a pinch or two of Dog Barf to hold the BP in place.
    Rex
    sequence is; assemble delay element, apply lube, place the O-rings rubber washer etc. in the closure, then pour in the ejection charge and gently set to one side. assemble the propellant (liner seal disc O-rings), floating closure and place spacers (as needed) in the motor case thread the ring thing in place. carefully turn the case forward end down and assemble the back end of the motor (washer O-ring nozzle and aft closure) you might want see if you can get a demo for this :). the rest of the motor prep is done on the pad with the rocket pointing in a safe direction (usually pointy end up). HTH
    Rex
     
    Last edited: Apr 18, 2019
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  7. Apr 18, 2019 #7

    Banzai88

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    We've all done this. You'll do it again. ;)o_O:)
     
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  8. Apr 20, 2019 #8

    Curtis Enlow

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    Getting there!

    Nothing to report but the boring stuff: Fabbing the backing plates and fitting the rail buttons, putting the last structural fillets on the fins, should tackle the aerodynamic fillets soon.

    This is the IV with the BT tube extension for the future HP/dual-deploy version. Not certain I will need the entire body tube section; I really haven't gotten as far as determining how much space I need forward of the elecronics bay, but it's fun to see it looking like a rocket!

    You all look at your half-built rockets and make 'WHOOOSH!' sounds and imagine how hard it's going to snap your neck back to watch it climb, right? Everyone does that, right? don't they...?

    [​IMG]

    I've decided on an homage to the 60's space race paint scheme, similar to the Gemini Titan II. Most of it, of course, can be done with paint, but I've been looking into it and I might have to try my luck at DIY decals for the vertical 'UNITED STATES' or get them custom printed.

    [​IMG]
     
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  9. Apr 20, 2019 #9

    rharshberger

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    Plans for the Macklin Missleworks Guillotine Fin Jig are available from Ted Macklin of Macklin Missleworks for a reasonable price.
     
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  10. Apr 26, 2019 #10

    Curtis Enlow

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    thanks, Rich! I see the plans are for the 'small' version, I assume one simply scales them up for larger builds? I've ben on the run with work, so i know I should just write them and ask...
     
  11. Apr 26, 2019 #11

    Curtis Enlow

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    Cut & mounted the switch band for the coupler. I need to decide on what style of switches I am going to use before designing the electronics sled. I am partial to the quality of the rotary switches, but like the simplicity of the screw-type switches. Leakage doesn't seem to be an issue unless you are allowing a large ingress of air into the compartment, but I don't think trying to finesse flush-mounted air-tight switches isn't realistic at this time (though I would love to do that). Advice on this matter would be appreciated.

    Shot the first (certainly not the last) coat of revealing primer the other day between gigs. It's always done with such trepidation, as it tends to be so revealing; no matter how smooth you think you worked things, in the (oblique) light of day all the little blemishes come out. I should have time to stop by the local hobby shop and get some lightweight sandable airplane filler (I find it's easier to work with than epoxy/micro-balloons or wood filler for touch ups). I know perfection is the enemy of good-enough, but...dang it...

    [​IMG]

    I have also cut the rough bulkheads for the stretched DD/HP version instrument bay coupler. I was a little shocked at how heavy 1/4" all-thread was compared to aluminum rod, and while I know stainless and aluminum don't get along too well, I am still considering threading the aluminum as the through-rod for the coupler - I'm not building the Brooklyn Bridge here, the aluminum can certainly handle the stresses of a low-range HP rocket, and I think if I protect against the intrusion of an electrolyte with a light oil I should be able to keep galvanic corrosion within reasonable bounds. It's a compromise but I think the weight savings is worth it.

    Hoping to make some of the high power fly-in's in May I need to make progress without cutting corners, and I am now anticipating recovery system materials I am going to need. The base IV comes with a nice 36" chute, but I am going to bump it up to 42" for the heavier, stretched Super IV (IV-B?). I am guessing (at this point) that I will wind up around 2kG in the final dual deploy version, so i need to get a decent drogue, as well. In YouTube videos I see that many rockets come down under drogue nice & stable, and some are gyrating all over the place; does the style of drogue have anything to do with that? Are there some that are just more stable? It's not just visual aesthetics, I am concerned about fouling the mains. Any advice on drogues and chutes in general this would be appreciated.
     
    Last edited: Apr 26, 2019
  12. Apr 26, 2019 #12

    Bat-mite

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    Yup. My last big one after I painstakingly constructed a very large MMT assembly, with three #10-24 threaded rods through the CRs, and made sure there was no stray epoxy when the fins would need to butt up to the MMT, happened when I finally inserted the MMT and CRs into the booster.

    All day long I had been reminding myself: "align the threaded rods between the fin slots. Align the threaded rods bewteen the fin slots."

    So that night, after work, after dinner, after getting kids to bed, I excitedly rushed down to insert the MMT into the booster, and ...

    ... paid no attention, and aligned the threaded rods with the fin slots, so that the fins could not go in. Fortunately, there was no epoxy yet. But getting that tight-fitting thing back out of the booster cost me an hour of building, and resulted in a ton of frustration.
     
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  13. Apr 26, 2019 #13

    Curtis Enlow

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    Of course! 10-degrees rotation either way and you would have been fine. Fate is a cruel, but efficient, teacher ;)
     
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  14. Apr 26, 2019 #14

    Curtis Enlow

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    Prime. Sand. Prime. Sand. Prime...sand...

    [​IMG]
     
  15. Apr 28, 2019 #15

    Curtis Enlow

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    Prime. Sand. Prime. Sand. Day 3

    Bought Dupli-color adhesion promoter for the nose cone and Dupli-color sandable primer. I'm really surprised at the difference in quality of the primer vs. the basic Krylon automotive primer. I'm still torturing myself over very, very minor unevenness in a couple spots in the fillet areas; I need to let it go. Generally, it's looking (and feeling) good. The biggest thing I am dealing with now is a little bit of fabric texture in the fins from the cloth.

    [​IMG]

    While the primer was doing its thing I cut out bulkheads for the electronics bay coupler with my scroll saw and, after making a simple collet out of a 1/4" bolt, put them in the drill press and sanded them down to a snug fit.

    [​IMG]

    Tomorrow...hmmmm, let's see what's on the schedule. Oh, will you look at that? Surprise. More sanding... But I think I will also get out the tap & die kit and see about cutting threads in the aluminum rod for the stainless eye nuts, as well.

    Spent a lot of time looking at recovery, and I think i am going to go with Spherachutes - a 48" main and 18" drogue (being spherical, the openings are actually approx 30" and 11", but with higher drag coefficients than flat chutes). I hear nothing but high praise for their products - great quality and top shelf customer support; you can't beat that.

    To do list is: Lay out RRC2-Minis (I have two, they are small & light and I think dual-redundancy is always a good thing if you can do it. It would be a shame to lose a rockets for want of saving a few grams) and work on designing the electronics sled. I have an extra 1/8" coupler bulkhead, and think it might be a good place to mount switches for the switch band.

    I ordered plastic vials for deployment charges, as well as e-matches. Cups and connector blocks look cool, but I like the weight savings and simplicity of just running match wires through the bulkhead. I would think black powder corrosion could be a failure point in connector blocks unless you were religious about getting in there with a 00 jewelers file and cleaning them up on occasion. I need to look into either printing my own 'UNITED STATES' decals or having a custom sheet printed. I looked at LEUP rules & regs until it gave me a headache...

    It's fun seeing all the threads come together, but I just don't see myself making the early May HP fly-in's in the desert, not with dual-deploy ground testing, paint & finish, etc.. There are some in early June I am going to shoot for. There's no sense in rushing things - it's the journey, not the destination.

    Found out something extraordinarily cool today, though: I am going to be doing sound on a video segment for local & national news on the Apollo 11 capsule exhibit at the Museum of Flight in SEA. We'll have unfettered after-hours access to the capsule (no motion detectors!) and we are going to be able to get up close & personal. Yes, I will post pics :)
     
  16. Apr 29, 2019 #16

    Curtis Enlow

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    Making further headway.

    I have the primary coupler/instrument bay completed, just need to design the sled and figure out how I am going to mount the switches. I have been wanting to use disposable plastic centrifuge-style vials for a number of reasons, but have been concerned about a couple things and ha some questions. Got some great tips and learned some things from the https://www.rocketryforum.com/threads/black-powder-charge.142926/page-3 thread, including some tips from Banzai on containing the vials and insuring the powder is consumed in the initial event, instead of still-burning powder being distributed around the space.

    I obtained some 1/2" PVC caps from the local hardware store - cheap, strong and surprisingly light. I'll wait for the 2g vials to arrive before i actually drill any holes, just so i can make sure everything is going to fit correctly.

    [​IMG]

    So. Back to Amazon. I actually dislike Amazon, but there are some times when you just need to do what you gotta do, and I have no idea where I can get 1/8" removable plastic rivets locally, and I need the rotary switches, as well, and quickly, if I am going to continue good progress working on the coupler/sled while paint is curing.
     
  17. May 6, 2019 #17

    Curtis Enlow

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    Now that my Dad's out of the hospital...

    Made some progress the avionics bay! I am going to use two 300mAh lipos (90C), a RRC2-Mini and decided to get an RRC3 w/USB from Jim at Missileworks, as well as two screw switches and guide blocks. I will put the altimeters on one side, and the batteries on the other side to balance things out a bit. The altimeter and switches should be here by Thursday, so the switch locations/mount will have to wait. Also, the parachutes came from Spherachutes, so I need to do some work on the shock cords now and need to decide on how I am going to put chute attach loops in.

    [​IMG]

    I have a prototype for the top-down firing charge cups (you can see the plastic vial inside) but am having a heck of a time finding black powder locally. I'm sure a can will last almost for ever, but....wow...even Cabala's doesn't carry real black powder anymore...?

    [​IMG]

    A final light sand on the primer on the body tube(s) tomorrow. The nose cone came in a little late on the process, so I need to do a little more primer there before laying down the white base coat.
     
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  18. May 9, 2019 #18

    Curtis Enlow

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    First Base.

    That unnerving moment when you finally lay down the first coat of base paint.

    At times I have thought the purpose of my life was to serve as a warning to others, and...I made a mistake, and I don't mind sharing it so that other new rocketeers who might be reading this can learn from my example. When I epoxied in my fins I did a two-step process: First, I ran a small fillet of epoxy with milled glass fibers for strength, then I ran the aerodynamic fillet with epoxy and micro-balloons. I should have only ran the epoxy with fibers only along the straight edge of the fin, leaving the strakelet area bare. But I didn't. that was a mistake. Strakelets are tricky enough to blend nicely as it is, and the epoxy with milled fibers is hard as a rock and it will not fair in nicely. The micro-balloons sand very nicely without being harder than the cardboard, so you get a nice blend with it. However, I had just a little too much expoxy with fibers at the strakelet, and it would be best to have none at all. So, to my disappointment - while not a major aesthetic issue - I can detect the edges and I'm not happy about that. But, live & learn.

    I also put a bit too much white on the NC and it ran, so I will have to wait until completely dry (it's warm today, so 24-hours should do it) to sand that down before I can apply more coats to the NC.

    Dupli-Color sprays on very thin; it flows nicely but will run, so be careful.

    [​IMG]
     
  19. May 9, 2019 #19

    Curtis Enlow

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    Avionics sled is coming along nicely. Just waiting for MissileWorks to hit their once-a-week 'Shipping Day'...:confused: and another 3-days after that to receive the goods so I can finish layout, routing, etc..

    [​IMG]
    [​IMG]

    90-mile (round trip) to the only black powder source in NW Washington State tomorrow. Better hit the rack...
     
    Last edited: May 9, 2019
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  20. May 10, 2019 #20

    Curtis Enlow

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    Perty in white.

    This is the white base coat for what will eventually be an homage to the Titan II of Gemini fame.

    The tall version is the HP mod with coupler and upper BT. The shorter version is the standard LOC IV.

    Unfortunately, black powder is out of stock until late next week, so testing of the charge cups are put off. Missileworks shipped today, so I should have the RRC3 and switches soon.

    [​IMG]

    [​IMG]
     
  21. May 12, 2019 #21

    Curtis Enlow

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    Here is my single-rod design for the avionics bay so far. Using aluminum all-thread and washers, nuts, etc., made a tremendous difference in weight, essentially giving the batteries (and some of the electronics) a free ride.

    Waiting on the re-flashed RRC2-Mini from Jim at Missileworks to do the final routing and switch install. The RRC3 will be the back up altimeter, as it has the drogue delay option. I will use aquarium tubing hot glued into place to serve as guides and hold-downs for the e-match wires. I also need to trim the excess threads on some of the fasteners for weight. I am using screw-type switches which will most likely mount to the upper bulkhead. In hindsight the switch band was not necessary with that kind of installation, but it doesn't seem appropriate (or necessary) at this point to build in some sort of elaborate bridge to place the switches in the switch band. I culd mount them on the sled at the band location; I will wait until they arrive to get a better idea of ho that will work. Generally, I like the added strength the band imparts when holes are drilled through the body tube; Still undecided at this point. I will, however, locate the vents there for a centralized location.

    The e-matches will go into centrifugal plastic vials and will be downward firing into the cups, and the vials will be stabilized with packing & tape. I used a high-pressure tube to extend the blast cups. they are particularly tough, and being open-ended, should survive the small amounts of BP i will be using, and will direct the blast into the body tube. The outer bulkheads were painted with heat resistant paint.

    I have plastic tubing on the battery retaining/electronics mount stand-offs, and have tried to use the fasteners in such a way as to serve multiple purposes, when possible, to save weight. Keep in mind this is a small, 4" low-range HP rocket - it's light, but structurally very strong, so I think it will serve it's purpose well.

    Any comments, concerns, corrections or suggestions would be appreciated!

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: May 12, 2019
  22. May 13, 2019 #22

    Curtis Enlow

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    Some good input on another thread about using neoprene washers to seal the center rod and cup fasteners, as well as safety wiring the eye nuts so they can't spin loose during deployment. I will implement all of the ideas.
     
  23. May 19, 2019 #23

    Curtis Enlow

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    My Dad is back in ICU, and work has been heavy but I have made a little progress. I find working on this gives my mind something else to do other than worry...

    I installed neoprene fender washers under the rod load-distributing washers to help seal the avionics bay. I also installed O-rings under the charge cup fasteners. My no be a perfect seal, but should reduce blow-by to a minimum.

    I use the Labeler to make labels. Seemed like a good thing to do to keep me from making some bonehead move (which I have been likely to do lately). I have also installed the upper BT retention fasteners for the coupler. I used 4-40 screws into T-nuts and a 1/8" ply backing. I also used small nylon bushings that protrude through both the couple and BT wall. They increase the bearing size and make the holes less likely to deform.

    [​IMG]

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    Because I have an avionics bay with shouldered bulkheads I needed a way to connect the e-matches upon closing the 2nd end with pigtails from the altimeters, as the altimeter connecting blocks are then unaccessable. I figured it was better to run short lengths of soft, pliable silicone multi-strand up from the altimeters instead of long, solid-core, stiff sires down from the forward charge cup e-matches. I installed two connector blocks on the interior side of the forward avionics bay bulkhead. Yes, they are small, but they aren't exposed to the charge blast, carry no structural loads other than the negligible weight of the wires, and need only do one thing - make an electrical connection to the e-matches. They are rated for the electrical load, and, while designed for PCB install (with through mounting pins) I drilled holes for the pins, roughed up the pins with wire cutters and epoxied them into place. They should be fine for their purpose. I can pre-install the e-matches and their wires and tape them down and simply connect to the altimeter outputs upon final assembly.

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    That's it for now.

    So much more to do - ground testing (providing Missileworks doesn't wait another weeks to send me my re-flashed altimeter and corrected order), exterior design & paint, ordering more 1/2" nylon strap for HP DD shock cords (the LOC IV came with 15-feet of 7/16" strap for MP flights), final weighing and balancing and ordering MP & HP motors for the early June fly-in...all providing my Dad continues improvement. It's okay; gives me something to think about...
     
  24. May 21, 2019 #24

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    Laid down the aluminum layer for what will eventually be a Titan II-like paint job and homage to the mid-60's space race. The proportions of my LOC IV in standard & extended HP/DD version aren't quite the same as a Titan II, but it will have a 'look & feel' and that was all I am going for. I also had to lay it out in such a way that it would make sense in both the standard and stretched versions. It still needs the black roll bars to pull it together, but it's getting there.

    I let the white base coat cure for quite a while - a week or two, at least - while working on the av bay, etc., and everything went well. I used low-tack Blue Hawk masking tape and had zero issues with Dupli-color pulling loose.

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    [​IMG]
     
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  25. May 21, 2019 #25

    mbeels

    mbeels

    mbeels

    Putting the tree in rocketry

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    I hope your father fully recovers.

    Beautiful rocket, I especially like the way you finished the Av bay. Very nice.

    And the fins are gorgeous.
     
  26. May 22, 2019 #26

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    Thank you for your kind words, Marten, I appreciate it very much.

    I was hoping to have my switches before finishing the AV bay, but due to a shipping error they will be a week and a half late, though I should have them tomorrow. Locating and drilling the vent/access (they are screw-type switches) holes and mounting the switches with accuracy will be interesting, and you might have spoke too soon ;)

    Thanks, again,

    C
     
  27. May 25, 2019 #27

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    Received my screw switches and re-flashed RRC2-Minis from Missileworks, so I installed the Mini and made mounts for the switches that matched the switch band on the AV Bay/coupler. They say "Measure twice; cut once" but i think I measured about five times. I didn't want to have to repair a poorly placed switch access hole, so I tormented myself over the location until i was certain that the hole location would lie directly over the head of the switch screw. The screw guides for the screw switch from Missile works certainly makes it easier, and they are well worth the price!

    Other than vent holes, and a small adjustment on the mains bulkhead wiring (I had to resort to stranded copper 18-guage wire for the hook up to the main blocks, but am not happy with it, and so I need to scrounge up some 18-guage silicone wire. Hopefully, the R/C car & truck place has some in stock), I think I am ready to paint the switch band and proceed with testing. A couple things: Aware that is probably as much an exercise in designing & building an AV bay as it was a necessity (some have suggested that I keep it simple and go for a single-deploy L1) I tried to incorporate things like the a single-rod AV bay assembly and using the zip-ties as wire organizing & hold-downs as much as possible to keep weight and complexity down, which I think worked well; the entire AV Bay weighs 552g, and that's all-in - dual redundancy systems: two batteries, two altimeters, wiring, clamps & mounting - everything but the actual charges. I don't know what other AV Bays weigh in comparison, but I would like to think mine is at the lower end of the scale...

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    The switch guides are close to the coupler tube - in fact, as close as I could get them. I will locate and drill separate vent holes for the bay that have free & open flow, not partially obstructed by switches, etc.. I don't know if that makes much of a difference, but it can't hurt and whatever leakage around the switch guides that occurs won't be a bad thing - better too large of a vent hole than too small of one. My local hardware has a nice assortment of small, shouldered nylon bushings that would really 'dress up' the vent holes and i thought about using them until I realized they would actually create a low-pressure area at the hole, like half of a venturi, so I'm glad I didn't make that mistake ;)

    Otherwise, I have completed sewing that recovery harnesses. For the dual deploy drogue I used 30-feet of 1/2" Nylon webbing with a reinforced loop for the drogue at 1/3 of the harness length. For the mid-power base IV version I used 18' of 7/16" Nylon webbing that came with the kit, also with a loop at 1/3 the length for the main chute. The advantage is that (and opinions vary widely on this) in the stretched High-power dual-deploy version I have 6 times the length for the drogue, which is in the ball-park of the opinions I have found here in the forum, and the 15-foot 7/16" should be fine as the main harness at 3 times the total length of the DD version of the rocket.

    I have also included a swivel that can be used in both versions. The opinions seem to vary on the use of swivels but are generally good.

    [​IMG]

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    So, next: Vent holes in the AV Bay, and then on to laying out the black layer of the final paint design. Functional test of the AV Bay assembly with LEDs in RRC3 'Sim Mode' and then testing all up in the yard with charges (after warning the neighbors, of course). Weather permitting the 7th, 8th & 9th Swoosh fly-in at Tri-Cities is coming up fast, especially with a three day business trip coming up soon and some more scheduled gigs. It will be tight, but i think i will make it, though it means maidening the IV on mid-power there, and then going for my L1 on the second day, barring any catastrophic problems on the mid-power maiden.

    My weight on the basic IV came in much lower on Open Rocket than the actual did, until I weighed an empty and full can of the spray paint i have been using after which i realized where the extra 528g of weight came from ;) the good thing is that i think i will still get it under 1500g for flying on a 29mm 'G' at the local field, so that will be nice - fingers crossed!
     
    Last edited: May 25, 2019
  28. May 26, 2019 #28

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    Laid out, masked and painted the black layer on my rocket. Despite my best efforts some of the black (and underlying white) came off with the tape (it was raining and humid today - that's my excuse and I'm sticking with it), so touch-ups are in order. I still need the gold band at the bottom of where the adapter module would be, and some protective clear coat. The proportions are different than a Gemini/Titan II (too tall/thin) but I think I captured the look & feel.

    I also laid out and drilled the vent holes in the AV Bay switch band. I think I've got my cardboard hole drilling down: I drill in stages, using CA and letting it soak in and harden between each drill size. It gives nice, clean hole after sanding inside and out - no ragged edges at all.

    [​IMG]
     
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  29. May 27, 2019 #29

    mbeels

    mbeels

    mbeels

    Putting the tree in rocketry

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    That is definitely very reminiscent of a Titan! I bet the gold band will add a nice splash of color. I like the motif, very classy.
     
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  30. May 27, 2019 #30

    Curtis Enlow

    Curtis Enlow

    Curtis Enlow

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    Interestingly enough, I think that even among brands like Dupli-color there are slightly different formulations that may not be entirely inter-compatible. The solvent used in the 'Universal Black' didn't affect the Silver in any way, but definitely affected the much older (and more thoroughly cured) white base coat, softening it and pulling it up right down to the base coat in a couple of places.
     

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