ECEE THUNDER BUILD and TEMPLATES

Discussion in 'Rocket Boosted Gliders' started by Rktman, Jun 24, 2019.

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  1. Jul 3, 2019 #61

    Rktman

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    Eric Noguchi

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    Impressive, especially Ari's flight. The 1st one looked kinda painful though. :eek:
    Wonder what these Thunders tipped the scales at?
     
  2. Jul 4, 2019 #62

    mikec

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    Mine is 8.7 oz (bare balsa).
     
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  3. Jul 6, 2019 #63

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    Eric Noguchi

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    Thanks for that benchmark. Hopefully can get to weight mine in a few days.
     
  4. Jul 6, 2019 #64

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    Eric Noguchi

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    Fuselage sides are now on. I decided to reinforce the area that some fliers have reported has a tendency to break sometimes (I believe mostly because the small stock vent hole wasn’t enlarged. With better venting that piston would be traveling at a lower velocity and the impact would be less).

    It’s the area right at the notch in the fuselage that allows clearance for the canard flap when it swings down. It’s also the area where the piston slams into the bulkhead as well as the small balsa lever that rotates the flap downward.

    I cut 1/64” ply to strengthen that portion of the fuselage.
    fuse reinforcement.JPG

    fuse reinfd.JPG

    Almost ready to button things up!
    IMG_3583.JPG

    These leftover shapes on the ¼” balsa sheet, if you downloaded the templates and were wondering, become the nose piece after they’re laminated.
    IMG_3588.JPG
    IMG_3595.JPG
     
  5. Jul 6, 2019 #65

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    Eric Noguchi

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    Motor tube just went in.

    Just an observation: the glider is actually a fast and fairly easy build if you leave everything absolutely stock and don’t do stuff like rounding off edges, tissuing, or otherwise make any changes or “enhancements” like motor retainers, enlarging the vent hole, etc.
    IMG_3591.JPG
     
  6. Jul 8, 2019 #66

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    Eric Noguchi

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    Minor problem I was aware of from a review elsewhere: the plastic hinge tape supplied in the kit has a tendency to lift/let go. The comment I read advised using RC plane hinges, and luckily I just happen to have a supply of the larger Du-Bro variety. It’s all good though, the tape will hold the flap in alignment and the plastic hinges will ensure the flap stays attached. I’d advise anyone building an Ecee to use RC plane hinges from the start though.
    hinge-2.JPG
     
  7. Jul 8, 2019 #67

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    Eric Noguchi

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    I had to trace around the Du-bro hinge and cautiously cut through and remove the hinge material without damaging the balsa underneath. Fortunately things went pretty smoothly.
    peel tape.JPG


    I had to cut a relief for the hinge knuckle so each leaf would lay flat and be in full contact with the flap’s surface. I used a Dremel but as you can see, it didn’t cut as smooth a groove as I expected it to. Resorted to doing it manually with an X-acto blade and router tip.
    hinge groove.JPG
     
  8. Jul 9, 2019 #68

    BABAR

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  9. Jul 11, 2019 #69

    Crawf56

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    Very nice work. :)
     
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  10. Jul 11, 2019 #70

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    Eric Noguchi

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    May have to resort to this option if the nylon hinges start to loosen. For now I'm trying to minimize even small weight increases since I had to add 12.08g (about half oz) of trimming weight to get the CG where it needs to be.
     
  11. Jul 11, 2019 #71

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    Eric Noguchi

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    Thanks appreciate that. Part of the enjoyment was the build of this classic original. Will probably get some snaps of the Thunder sometime today.
     
  12. Jul 12, 2019 #72

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    Eric Noguchi

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    Epoxied the Du-bro hinges in place.
    hinges.JPG

    Ran into another hiccup when the hinge tape started buckling and pulling loose, interfering with the flap swinging freely. I’m guessing it has something to do with the geometry of the plastic hinges subtly changing the arc of the flap’s rotation a minute amount. The plastic tape didn’t like that. Had no choice but to slice the tape the full length of the joint. Oh well, works fine now but the tape is now nonfunctional.

    I think if I had to do it over again, I’d place the plastic hinges on the bottom side of the canard (i.e. on the side the flap swings toward). I think it would’ve allowed more freedom of movement and I wouldn’t have needed to mess with the hinge tape. Valuable learning misstep.

    Also for the forward top fuselage nose piece, I’d replace that 1/4” balsa with 1/8”. It felt plenty heavy and using a lighter piece would’ve shaved off most of the trimming weight needed for the aft end (12.08 grams).
     
  13. Jul 12, 2019 #73

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    Eric Noguchi

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    Done and ready for the pad.
    45”L x 27” wingspan @ 9.8 oz with expended engine casing and 0.43 oz of trimming weight inclusive. A tad on the heavy side.
    IMG_3636.JPG
    IMG_3639.JPG

    Thunder and its smaller Ecee sibling.
    IMG_3628.JPG
     
  14. Jul 12, 2019 #74

    mikec

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    FWIW, I used CA hinges on mine, which are much lighter and better centered than these. It's quite easy to cut the slits for the hinges given the thickness of the canard balsa. First item on http://www.greatplanes.com/accys/gpmq3950.php
     
  15. Jul 12, 2019 #75

    BABAR

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    Straight trails!
     
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  16. Jul 12, 2019 #76

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    Eric Noguchi

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    Always assumed references to "CA hinges" meant the usual Du-bro variety but now I understand it's a hinge designed to absorb cyanoacrylate better, so thanks for url. Will switch to these for future builds.
     
    Last edited: Jul 12, 2019
  17. Jul 12, 2019 #77

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    Eric Noguchi

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    Thanks! Hoping for just that result when I get to fly this hopefully in September at a large (3,800 acre) field. If all goes well I'm also hoping to get some footage...or at least some stills.
     
  18. Jul 12, 2019 #78

    new2hpr

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    I just cut a piece of CA hinge material the size of the original tape, laid it across the joint between the fixed and moving parts, then CA'd to both. No slitting needed, as the canard only moves down. I guess it might be prettier with them hidden in a slit, but the full width hinge is beefy.
     
  19. Nov 9, 2019 #79

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    Eric Noguchi

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    Disappointed. Was hoping to finally get the Thunder airborne on its maiden launch next weekend, but with sustained double digit wind speeds and 43mph gusts forecasted, it'll have to wait for next month's Tripoli East launch date.
     
  20. Nov 29, 2019 #80

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    Eric Noguchi

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    Finally found some time to sew in the Thunder's canard flaps. Haven't had a chance to test fly it yet due to uncooperative weather conditions, but at least now I won't have to worry about the hinges coming loose.
    sewed in hinges.JPG
     
  21. Nov 29, 2019 #81

    kjm

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    Hi Eric --
    Just found your thread on the EceeThunder - my all-time favorite rocket glider!

    I have built and flown (and crashed) 3 of these magnificent boost gliders over a period of say 10 years. They were great flyers once all dialed and real crowd pleasers. The last one crashed in 2016 due an overly energetic E12-4 ejection charge which damaged the canard actuator. It never transitioned to glide mode and came in hot and fast -- hitting a rock (of course) on landing thus ensuring total destruction.

    But in an incredible stroke of good fortune, in 2017 I was able to buy (on Ebay) another one in a sealed bag. Thinking it was perhpas the *last* unbuilt Ecee Thunder in existence, I never wanted to build it until I figured out how to scan all the parts for posterity. And here you have done just that. Now I'm going to start building the kit this weekend!

    Many Thanks,
    Kevin.
     
  22. Nov 29, 2019 #82

    Rktman

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    Eric Noguchi

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    Glad to know that this thread served as a catalyst to get another one of these impressive gliders back into the skies. Would enjoy seeing your build/launch/flight pics here.
     
  23. Nov 30, 2019 #83

    kjm

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    Yes, I'll post some photos when I get started (soon!)

    Excellent job with your build, and good improvements. Especially enlarging the ejection gas hole and positive motor retention. The Thunder is very sensitive to fore & aft balance so keeping the motor retained is critical. Kicking the motor makes the glider nose-heavy resulting in a steep, fast descent (w/ damage on impact) instead of a nice graceful glide.

    I used an Estes 24mm motor hook with the forward tab ground off (so either D12-3 or E12-4 motors could be used), attaching it to the tube with a dab of JB weld. Worked great. And tape ring for fwd retention.

    I saw your motor retainer -- looks good and secure. If you haven't already done it, check how it affects the fore & aft trim. It may need added nose weight to get it to trim at the balance point marked on the underside of the fuselage. Always install an empty motor case adjusting the fore & aft trim.

    My previous builds always took 1/4 to 1/2 ounce in the nose compartment to trim out perfectly. I use short pins rather than glue to attach the top piece of the nose compartment so I can add or remove small amounts of weight in there for D v.s. E motors. And to re-trim after (the inevitable) repairs!
     
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  24. Dec 1, 2019 #84

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    Eric Noguchi

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    Great idea about using the pins to hold down the forward compartment cover. Wish I hadn't glued mine down.

    As an experienced Ecee Thunder flier do you think that a D12 is adequate to loft my 9.8 oz. Ecee high enough to safely deploy the canard flap?

    Also how do you deal with the balsa piston getting "frozen" in place from the heat and crud from the ejection charge? Yesterday I flew my 13mm Ecee and another glider that also uses a balsa piston and both jammed thier pistons in place because the heat tends to make them swell. I was thinking about replacing the balsa with a coupler with plywood discs glued to both ends.
     
  25. Dec 2, 2019 #85

    Ez2cDave

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    Eric,

    That's an interesting idea . . .

    I am pondering about being able to "fire-proof" the Plywood Disc by coating it with a thin layer of JB Weld ( good for 600 deg. F ) epoxy. JB Weld can be thinned with Acetone.

    There is also the possibility of using a Composite coupler, in place of a "paper" one . . .

    https://www.mach1rocketry.com/fiberglass-airframes.html

    Dave F.
     
  26. Dec 2, 2019 #86

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    Eric Noguchi

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    I coated the ejection-facing end of my balsa piston with JB Weld and it kept it from completely disintegrating, but it seems enough heat percolates through to cause swelling. While a fiberglass coupler would be an excellent fix, unfortunately I don't think Mach 1 has a 24mm coupler size. I've never worked with fiberglass BTs before so I'm not sure if a glass body tube could be used instead, with a piece sliced out longitudinally and the tube reglued (reglassed?) perfectly round again so it slip fits snugly inside the 18mm paper motor tube. Maybe it's easier than I imagine. If so it would be the ideal solution since it's so heat-resistant.

    I thought about using a 24mm cardboard coupler only because I used it as a piston in the first thing I scratch built after becoming a BAR: a helicopter recovery rocket. Glued plywood discs to both ends and coated it with epoxy and soaked the coupler with CA to reinforce it. The ejection charge drives the piston up and small wire hold-downs attached to it release the rotors. I was pretty clueless and wasn't aware at the time that there were easier ways to retain and deploy the rotors, but fortunately it worked real well and still works after 3 years and 5 flights even though it's a bit singed. Maybe instead of thick ply discs I could substitute some G10 fiberglass?
     
    Last edited: Dec 3, 2019
  27. Dec 2, 2019 #87

    Ez2cDave

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    Eric,

    I was on the phone with Steve Skinner ( a really nice guy ), from Mach 1 Rocketry, for almost 2 hours today.

    Among the many topics of discussion were their 18mm & 24mm FG tubes . . . They DO have Couplers and the website will be updated soon !

    Dave F.
     
  28. Dec 3, 2019 #88

    kjm

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    Mine weighed closer to 8oz (I tissued only the vertical stabilizers and the canard). At that weight they flew well on D12-3s. But I think with your 20-25% extra weight I'd stick with E12-4s.

    Regarding frozen pistons: well, they do get awfully sticky from the ejection crud. Maybe even stuck. Before each flight, I make sure the piston is free to move:
    • Push the piston into the tube (to boost position)
    • hold the glider vertically nose down
    • drop a 1-2 oz weight down the motor tube, knocking the piston forward
    • rinse, lather, repeat as necessary
    After a few times, this knocks the crud loose, freeing up the piston so it moves fairly easy -- but it's always a bit "gritty" and never friction-less. As you know, (and this is mostly for any future EC Thunder flyers reading this), the piston wants (and needs) a bit of friction to hold itself firmly against the canard actuator after the ejection charge has fired.

    I like your idea of coating the aft end of the piston with JB-Weld. I'm adding that to my build!
     
  29. Dec 3, 2019 #89

    Ez2cDave

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    Eric mentioned that the heat still caused the balsa to swell, even when coated with JB WELD.

    It might be a good idea to use a plywood disk on the Balsa Piston and then coat that with JB WELD.

    NOTE: JB WELD can be thinned with Acetone.

    Dave F.
     
  30. Dec 3, 2019 #90

    Rktman

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    Eric Noguchi

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    That's awesome! Seemed odd that they wouldn't have 'glass couplers, this makes much more sense. This is a great solution to the bothersome problem of short-lived balsa pistons. Thanks Dave, much appreciated! I'll be on the lookout for those couplers.
    Oh, and I had a senior moment...I meant 24mm coupler, not 18mm. Glad they have both.
     
    Last edited: Dec 3, 2019

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