Power Line Seeker II – 3” MD Project

Discussion in 'High Power Rocketry (HPR)' started by AlnessW, Aug 17, 2015.

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  1. Aug 17, 2015 #1

    AlnessW

    AlnessW

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    Hi all – usually, I do detailed, step-by-step build threads (and construction pages on my website) for each of my projects, but this time I’m going with the Steve Heller-esque stream of consciousness / runaway train-style approach as it fits the demographics of this project a bit better. I may add a more detailed build page to my website at a later date, but we’ll see what happens…

    Background
    This year has not been the most successful of rocketry seasons for me. So far, I’ve had absolutely zero luck getting a new project in the air (for numerous reasons), and what little I have been able to fly has not fared the best. This year I’ve experienced landing in high-voltage power lines, damaging a rocket on landing, a shred, and a ballistic recovery (where said vehicle was never found) to name a few.

    We have a club launch next weekend, and this launch is to be my grand attempt at turning things around. I have another new bird all ready to go, and am now adding this project to my agenda. The name comes from an earlier iteration of this bird that flew to 25K last March, landed in a power line, and took 3 months to return home to me involving numerous SNAFUs with the power company. If you want the whole story, just ask me about it in person sometime…

    Design
    These days, I mostly find myself conceptualizing a motor first, and then building a rocket around it. This project will be no different. I have an AMW 75/7600 hardware set that’s been sitting around here and I really want to fly it – already have the motor design all planned out and ready to be executed. This project will also serve as my personal goal of trying to break 30,000’ by the end of this year, now to just build a vehicle that will fit the bill.

    The concept is fairly simple – take a 60” x 3” Performance Rocketry fiberglass airframe, add a nosecone, fins, and av-bay, then see what happens. FedEx delivered my Rocketry Warehouse order on Friday, so we’re in business.

    Recovery
    For recovery, I’m still trying to master the art of dual deployment out of a single airframe. My last attempt had a major design flaw that involved my main shear pins having to withstand about 160 lbs. of force during drogue deployment. They failed on at least one occasion that I know of.

    This time, I’m using a design I learned from some AeroPac guys who came up to one of our launches earlier this spring. It involves a single separation point with a Y-harness. Basically, av-bay goes at the forward end of the motor, the nosecone and drogue are deployed at apogee, and then the main gets shot out of the airframe like a cannon. There is a more detailed description on the AeroPac 100K project page, and should make more sense once I have some visuals. Chutes will be a 2’ drogue and 5’ main from Rocketman. Power Line Seeker version 1 used a 6’ main which was a little generous, and challenging to pack in a short 3” diameter compartment.

    Altimeters are a Featherweight Raven3 (might be my favorite altimeter right now?) and a StratoLogger SL100.

    That’s all for now folks – stay tuned for more. Only 1 week until launch…
     
  2. Aug 17, 2015 #2

    bclark989

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    Sounds like a fun project! Of all of the different impressive aspects of the build, I will be the most impressed if it is ready to launch this weekend. I think if I had one week to build a rocket I would be lucky to finish an E2X :p

    See you at the launch!
     
  3. Aug 17, 2015 #3

    chuck5395

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    Wish I could be there this weekend to see it.
    Best of luck.
     
  4. Aug 17, 2015 #4

    emckee

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    :pop:

    We'll see you Friday!
     
  5. Aug 18, 2015 #5

    AlnessW

    AlnessW

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    Yep, looks like we are on track for this weekend...fingers crossed!

    Thanks Chuck - we'll miss you out there.

    See you in the sage!

    IMG_3751.jpg
    Rocketry Warehouse order, plus my 7600 case for comparison. ;) I think he sent me the wrong nosecone (5:1 Ogive instead of 5:1 Von Karman) but I may just go for it due to time constraints.
     
  6. Aug 18, 2015 #6

    T34zac

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    That looks like a VK to me

    Good luck with the flight
     
  7. Aug 18, 2015 #7

    patelldp

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    Agreed.
     
  8. Aug 18, 2015 #8

    cvanc

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    Best rocket name EVER :clap:
     
  9. Aug 18, 2015 #9

    OregonBAR

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    Wilson - fingers crossed for ya! I won't get to see it, but looking forward to the pics & success story (Filible’s Folly maybe?). Extra kudos for the compressed timeline :eyepop:, as it took me almost a month for my MDRM last launch!

    Thomas
     
  10. Aug 18, 2015 #10

    MarkH

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    I've got two 3 inch VK cones from Rocketrywarehouse, and initially I thought the same thing (thought it was ogive) when the second one arrived. I bought them about a year apart. Ultimately I concluded they are both VK and have the same shape, but they appeared to have cut the top and bottom ends shorter on the newer cone. It is shorter on the coupler side by about 3/4 inch so that it does not accept as much coupler (not good for mach 2+ flights). It is also shorter on the top end because they cut the tip of the FG shorter and used a more blunt aluminum tip. Putting them side-by-side I can match up the shapes by aligning them in the middle; the new one is just shorter.

    I talked to them via email, and wanted to send it back and get one that matched the first. But I guess they change things up from batch to batch and that is how the newer ones are. Trying to explain this to them was like talking to a wall, and I gave up after about 3 or 4 email exchanges and sending pictures.
     
    Last edited: Aug 18, 2015
  11. Aug 19, 2015 #11

    AlnessW

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    You boys are exactly right - RW got back to me this morning confirming that fact.

    Thanks! I always enjoy coming up with a clever name.

    Thanks Thomas for stopping by! Yep, will have plenty to report back for sure. I'll be at Fillible's Folly too, as well as Rocketober.

    My experience was exactly the same. About 9 months ago, I bought a 3" VK (actually from Proline Rocketry, but as I understand Gary is pretty much out of the business now) which was noticeably longer than this nosecone. I suspect you're probably right about the mandrel being the same, just with the ends cut a bit shorter and a more blunt aluminum tip. Unfortunately I can't do a side-by-side comparison as my old nosecone is buried out in the desert somewhere...

    And yes, I've found RW can be difficult to get in touch with sometimes. A good approach I've found is to call Curtis directly with inquiries.

    Anyway, back to business. I'll get some more photos up soon, but I did work on the nosecone, av-bay, and motor today.
     
  12. Aug 20, 2015 #12

    chuck5395

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    :sad:
    Well, now I'll get to see you launch it.
    ;) :D
     
  13. Aug 28, 2015 #13

    AlnessW

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    Chuck is correct... After nearly a week of all-nighters getting this thing ready, the launch was cancelled due to fire danger on the day before I was set to leave for Brothers. This was a huge disappointment (though I understand the reasoning) and adds to the string of bad luck this season that I just can't seem to shake. New plan - fly this thing at BALLS, then if I don't destroy/lose it, fly it again in the same configuration at the Rocketober launch in Brothers.

    Because of the time crunch, I went with a Max Q Aerospace fin can (same as Power Line Seeker I) from Binder Design. Though prophecy chewed my head off for it...

    Fin can components.
    IMG_3792.jpg

    Assembled and ready for action.
    IMG_3790.jpg

    Bolted/clamped down onto the airframe. Since we're using an internal motor retention system, we can leave the fin can flush with the end of the airframe.
    IMG_3807.jpg

    Now it looks like a rocket!
    IMG_3809.jpg

    On to the av-bay. Per my first post, it will be attached to the forward closure of the motor. This is easily done using a 1" x 3/8" bolt with a lockwasher. Shown here is my 75mm AMW front closure, with av-bay bulkhead/all-thread rods in place.
    IMG_3767.jpg

    Altimeters - Raven3 and a trusty old SL100.
    IMG_3769.jpg

    Altimeters and Featherweight screw switches mounted in place on the av-bay sled. (1/4" plywood.)
    IMG_3774.jpg

    And 9V batteries attached on the back.
    IMG_3775.jpg

    Inside the av-bay coupler, we drill holes and install #8-32 T-nuts with hobby epoxy. This is how the av-bay will be secured to the inside of the airframe.
    IMG_3815.jpg

    Forward av-bay bulkhead (with 1/4" forged eyebolt) ready to accept terminal blocks and charge caps.
    IMG_3794.jpg

    More below...
     
    Last edited: Sep 23, 2015
  14. Aug 28, 2015 #14

    AlnessW

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    Assembled bulkhead. Wingnuts usually work best for removable bulkheads, however with all the other "stuff" on here, they wouldn't have fit.
    IMG_3799.jpg

    Sled and wiring in place.
    IMG_3806.jpg

    Completed av-bay buttoned up and ready to go.
    IMG_3801.jpg

    Rocket with loaded 75/7600 motor and av-bay for comparison.
    IMG_3804.jpg

    IMG_3798.jpg
    Motor/av-bay assembly secured inside the airframe using #8-32 screws, with holes drilled to access switches.
     
  15. Aug 28, 2015 #15

    OregonBAR

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    Wilson - what a beast, that bad boy is all motor! What is PLS 2.0 simming out at, altitude-wise?
     
  16. Aug 28, 2015 #16

    AlnessW

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    Thanks Thomas! Indeed, this is the most "motor" I have ever flown in a rocket this size. I can only imagine that trend continuing...

    As far as altitude goes, OpenRocket sims PLS II out at around 33K at Mach 2.95. Sounds a little generous to me (as is often the case with simulations). With this fin can, I'd be happy if I get 30K.
     
  17. Aug 28, 2015 #17

    patelldp

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    As long as you're happy with it, do it. Odds are you significantly reduced any uncertainty you had with respect to rushing your layups at the 11th hour. You won't get the same altitude, but it seems like you're okay with that.
     
  18. Aug 28, 2015 #18

    prophecy

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    Yeah - Wilson, correct me if I'm wrong, but I believe PLSI hit 25k on the Aerotech 7600 load? Assuming that's correct, you'll likely see that or a hair less (due to heavier snap ring hardware) on your motor. My best guess would be 24k.

    As we discussed, a "middle-of-the-road" option between leaving it as-is and laying up your own fincan is to lay a fillet over the screw heads - I'm learning with my current project how much this little stuff matters. This will increase your altitude more than you think.

    Whatever you decide, can't wait to see this fly!

    -s
     
  19. Aug 28, 2015 #19

    AlnessW

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    Hit the nail on the head, Dan. Controlling variables is always reassuring, and this project seems to have enough as it is. And yes, I'll be limited on altitude but can live with it.

    Correct, PLSI did 25K on the Aerotech M1850W which uses a dumbed-down version White Lightning. (Said flight was the namesake of this series of projects.) I hadn't even thought about the whole heavier snap-ring hardware thing, but like you said, little things make a difference.

    I'm leaning towards the fillet idea, and I doubt I'd ever have reason to keep the fin can "removable." Can't wait to see your project, too!
     
  20. Aug 31, 2015 #20

    AlnessW

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    Nosecone anchors installed with my usual method of #10-24 machine screws, Kevlar, and West Systems epoxy. Check out my L3 build page for a more detailed description on how this is done.
    IMG_3830.jpg

    Completed nosecone with coupler epoxied in place using Loctite.
    IMG_3834.jpg
     
  21. Sep 6, 2015 #21

    AlnessW

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    Nosecone bulkhead installed.
    IMG_3846.jpg

    Rail buttons went on last night. I've tried several approaches for mounting rail buttons on MD rockets now, most of which have ended with a button getting stripped off either when loading the rocket on the pad, or during flight itself. Using a weld-on T-nut epoxied to the outside of the airframe and reinforced with Kevlar/West Systems epoxy has proven to be the best approach, as seen on Power Line Seeker I, Not an Engineer, and now PLS II.
    IMG_3856.jpg

    Completed rail buttons.
    IMG_3855.jpg
     
  22. Sep 11, 2015 #22

    AlnessW

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    Well folks, this may end up being my last update before I finally get to fly this thing.

    I ground tested my charges, beginning with .5g and .75g (surgical tubing) for the drogue. As I outlined in another thread in the Recovery forum, these would have given me 15psi in an 11" x 3" compartment. I thought this would have been more than enough, turns out I was wrong. Both charges did next to nothing and showed no sign of even stressing my shear pins. (3 x #2-56 nylon screws.) So I returned with 1g and 1.5g - now those did the job. Nosecone popped right off, but not hard enough to pull back on the harness.

    For the main, 1g was plenty to push the chute out of the airframe, which is packed pretty tightly in there. My final values will likely end up looking something like this:

    Drogue primary: 1.5g
    Drogue backup: 2.5g
    Main primary: 1g
    Main backup: 2g

    I may end up adding some visuals of the Y-harness system I'm using, as well. But for now, 13 days until Black Rock!
     
  23. Sep 12, 2015 #23

    COrocket

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    What are you using for tracking?
     
  24. Sep 13, 2015 #24

    AlnessW

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    900 MHz Beeline GPS.
     
  25. Sep 21, 2015 #25

    OregonBAR

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    Wilson - just wanted to wish you a great flight of PLSII down at BALLS, you deserve a trophy after all the time & efforts you selflessly put into coaching and mentoring us up-n-comers, act as LCO at Fillible's Follies, and yet still are able to put together a great-looking rocket! :clap:

    "To the moon!"
     
  26. Sep 22, 2015 #26

    bclark989

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    Echoing this! Thanks for all the help, good luck in the big desert, and see in our desert in October!
     
  27. Sep 30, 2015 #27

    AlnessW

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    Thank you both for the kind words! Sheridan is fun...but what can I say, BALLS is more my scene. :)

    I flew this bird last Friday and the results were not optimal. I'll elaborate below, but first, a few finishing touches on the rocket itself.

    An issue many people have identified with ProLine filament-wound nosecones is the lack of a shoulder on the aluminum tip. They are simply manufactured with the tip sitting on top of the nosecone, secured with a bolt. This can be very easily dislodged (as was the case with my 5") and hence a better solution is needed.

    A 3/4" PVC end cap does the trick, however it's a bit big so we'll need to trim it down. Cue the "redneck lathe," as I learned from Steve H.
    IMG_0052.jpg

    I ended up having to shave off a lot more than I had planned, but it worked perfectly. The entire assembly is then glued into place using Loctite E-120HP.
    IMG_3898.jpg

    At BALLS this past weekend, I flew this rocket on an EX M2000. (My motor.)

    Ready for launch! Photo credit to Robert Braibish.
    IMG_3909.jpg

    Practically shaking out of nervousness, I pushed the button and the motor took its sweet time to come up to pressure. When it did, it leapt off the pad on a huge flame about as long as the rocket on its way to (I estimate) 26K-27K. At apogee I got no updates from the GPS, followed by several seconds of silence followed by the ever un-reassuring “1 update, then a thud.” We drove to the last coordinate and found this...
    IMG_3911.jpg

    Looks like I shredded my main at 1000’, since the nosecone had deployed and was sitting about 10’ from the “crater.” This may be the second time surgical tubing charges have failed me, so time to rethink that plan for next year. When the rocket augered in, the impact actually shot the aft snap ring, washer, and nozzle clear out – talk about some serious force there! There were pieces of liner scattered all over the place. Getting this thing out of the playa required a system of straps, levers, and Robert’s SUV – but it did the trick.
    IMG_3916.jpg

    IMG_0107.jpg

    The nosecone and GPS are fine, but the Raven3 and SL100 are both toast. That sucked for sure. However, my main goal with this project was getting the motor to work, of which it did perfectly, so I’m happy with that. Good thing this rocket didn't cost me an arm and a leg to put together, and I already have plans for the next one.
     
  28. Oct 1, 2015 #28

    OregonBAR

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    Hey Winston - Dang, sorry to hear about the "lake stake" :facepalm:, but glad to hear about the great burn on your motor...26-27K is a pretty impressive DIY! Nice job, and great attitude on taking what you can from this and looking to the next one :wave:

    Also, thx for sharing the build thread, great info for us noobs on what all goes into an L3 -type project.
     
  29. Oct 6, 2015 #29

    AlnessW

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    Thanks Thomas - a bummer indeed... I too, am glad the motor worked! Manny posted a photo of this flight in the BALLS thread, and the flame is longer than the rocket.
     
  30. Dec 28, 2015 #30

    AlnessW

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    Hi all,

    A few remaining photos and a report I never posted, plus a hint of what's next...

    Much to my surprise, there was more salvageable from this rocket than I had expected. Since the nosecone had deployed, it along the tip (since I had shouldered it) were unscathed, as was the GPS housed inside. After some major repairs thanks to Mike Fisher, both the fin can and motor case were saved!

    As you can see here, the fin can shot forward into the playa upon impact, shearing off the aft rail button and getting bent up pretty badly.
    IMG_0145.jpg

    After prying the forward bulkhead free, this is what remained of the altimeter bay...
    IMG_0141.jpg

    Chipping the pieces out with a screwdriver, we have isolated the bent up all-threads as well as the bolt used to secure said bay to the forward closure of the motor. I was pleasantly surprised that the motor case dropped right out the bottom of the airframe after removing this bolt.
    IMG_0142.jpg

    What remains of a Raven3, an SL100, and a few 9V batteries! Nothing usable here, obviously.
    IMG_0148.jpg

    The motor case was badly damaged, too. Upon impact, the nozzle and aft washer/snap ring got shot right out, along with lots of little pieces of liner. The washer and snap ring were never found, but the nozzle landed about 30' from the crater. It was chipped and broken very badly so I threw it out.
    IMG_0143.jpg

    Not entirely sure how, but the forward snap ring groove got stretched as well.
    IMG_0144.jpg

    I shipped both parts (motor and fin can) to Fisher who was able to repair them for a nominal fee. The damaged ends of my motor case were trimmed off with new grooves (3 of them) re-machined, yielding a 34.5" case. Returned to me here, good as new.
    IMG_0221.jpg

    My fin can needed to be re-formed on the metalworking equipment, as well as a large gouge (where it hit my rail button) cut off. Again, shipped back to me like nothing was ever wrong with it!

    I threw out what remained of my fiberglass tube, as it was in rough shape and really too short to be used for anything besides altimeter bays. Plus, I was worried about stress fractures weakening the tube. My main chute was never recovered, as it more than likely was obliterated upon deployment and probably blew clear to Winnemucca. The drogue and harnesses were all trashed.

    So, despite my misfortune, I still have a fin can, motor case, and nosecone to play around with. Steve and Manny (prophecy and mannyskid, respectively) have already made me a badass motor using Sunday Silent propellant for my shorted 75mm case, of which I'll fly whenever I'm in their neck of the woods next.

    As Aidan (tuxxi) said at Black Rock after I brought the remains back to camp, "I guess there were some underground power lines somewhere nearby where it impacted..." :wink:

    Needless to say, "Power Line Seeker III" will be materializing in the near future, so watch for a build thread sometime over these next few months. I have a good design planned already - this next iteration will be more optimized for altitude as opposed to just "slapping something together quickly to fly a big motor in." Hence, the fins will be 1/8" G10 with big fillets and carbon fiber tip-to-tip.

    I also need to find a more reliable method of getting a rocket open above 25K, which we'll touch more on later. But for now, that's all folks!
     

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