Double Shuttle has double cato

Discussion in 'Rocket Boosted Gliders' started by aerostadt, Feb 21, 2013.

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  1. Dec 26, 2018 #91

    aerostadt

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    Rktman, There is a lot of detailed information there. I think I would agree with you that strength is pretty important for my application.

    Frank, I did use iron-on monokote years ago on the Estes AstroBlaster and Dr. John Kallend's LadyHawk years ago. The finished product looked very good, but I spent a lot of time working on the monokote. I am so far happy with the balsa white-glue coated label paper.
     
  2. Dec 27, 2018 #92

    aerostadt

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    It is easy to cut the wing material with a scroll saw. I took my electric ironing tool for applying monokote and tried it on the wing that had label paper with white glue and tried to get rid of the wrinkles. I think it helped a little bit. Elmer's white glue has vinyl in it, so applying a hot iron tends to melt the vinyl slightly. I found that it was best to take the sock off the iron and move the iron slowly while pressing down.
     

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  3. Jan 13, 2019 #93

    aerostadt

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    I had Boyce Aerospace make new 3D printed plastic T-sections for the Double. The fit of the parts is excellent. Shown is a photo for the vent tubes dry fit of the two shuttle halves along with some close-up photo's of the T-section 3D printed parts.
     

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  4. Jan 17, 2019 #94

    aerostadt

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    I glued the T-sections into the vent tubes for both half-shells. I coated the tubes before gluing with a sodium silicate solution except where the tubes were glued. I had some concentric tubing left over from a previous project that slid nicely over the tubes making the tubes double-walled. A dry fit with the wings looks good. Boyce Aerospace met the specified height of the protruding T-section just right so that it is flush with the wing surface.
     

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  5. Jan 18, 2019 #95

    Crawf56

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    Wow. Great work! :cool::cool::cool:
     
  6. Jan 18, 2019 #96

    Rktman

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    Eric Noguchi

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    IMPRESSIVE! Precise, clean craftsmanship too.
     
  7. Jan 18, 2019 #97

    burkefj

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    So do these interlock somehow and then the ejection charge blows them apart reliably via the vent holes?
     
  8. Jan 19, 2019 #98

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    See Post #63.
     
  9. Jan 19, 2019 #99

    aerostadt

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    Frank, that's right. It looks great, when it works. I am hoping here to improve the design and construction to increase the reliability. Another factor on the reliability is the cluster of two E12-4's, but I am partial to that motor. Perhaps, I could cluster a pair of 24 mm composite motors, but my frame of mind is not there, yet.
     
  10. Jan 23, 2019 #100

    aerostadt

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    The last T-section went in very good. The tolerances of the 3D printed parts are very good. The T-sections are essentially flush with the glider's undersides. I wanted to show the Boyce Aerospace nose cone halves before gluing them in place. Again, the tolerances are very good and consequently the fit is very good. The printed nose cones are a little bit heavier than balsa. I find that a comparable hollowed finished (balsa filled and finished) balsa nose cone is about 1.87 ounces, whereas the plastic printed (unfinished) nose cone is 2.56 ounces. It is getting harder to find the balsa nose cones, so I'm going with the printed nose cones. Holding the printed nose cones to the light shows that they have some kind of standard 4-sided internal fill. The plastic nose cones appear to be very strong and gluing them in place will make the model even stronger.
     

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  11. Jan 28, 2019 #101

    aerostadt

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    The short vent tubes are roughly 24 mm diameter. The white tube shown is a thin wall tube from Balsa Machine Services and I think the thick brown tube that fits inside is from e-rockets. At first I had trouble getting the vent tubes from one rocket glider to align and fit in the mating glider, but then I sanded the T-sections on one side very slightly with a Dremel tool. After several dry-fits I used Testor's plastic cement on the front and back tubes and then later I glued in the middle tube. For the final assembly I need to fit the two gliders together, so that all 3 vent tubes mate simultaneously. With a little bit of practice this works pretty good. The final clearances and tolerances are very good.
     

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  12. Jan 29, 2019 #102

    Rktman

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    Eric Noguchi

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    Amazing work, very slick!
     
  13. Apr 16, 2019 #103

    aerostadt

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    The new Double Shuttle with 3D printed parts flew at the UROC launch on Saturday. It flew with a cluster of two E12-4's using e-matches from Blackjack. I tamped the e-matches in place with a tiny amount of tissue paper with a tiny screw driver and put masking tape on top for good measure. Doing this I was able to prep fast and the ematches seemed to hold in place well. I had the wrong mindset thinking that this Double Shuttle was the same as previous versions even though the nose cones were heavier and so I did not use any pre-set "up" elevons. I think now that this was a critical error. In any case one glider came straight down and had considerable damage. Fortunately the other glider worked enough to sustain no damage.

     

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  14. Apr 16, 2019 #104

    Rktman

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    Eric Noguchi

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    Sorry to hear one twin didn't make it. Did the one that survived have some up flap? Just wondering why one glided while the other came in ballistic. (At least you had a 50% success rate).
     
  15. Apr 17, 2019 #105

    aerostadt

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    I'm thinking that the condition for gliding was just marginal. It is hard to see in the video, but it looks like the one that glided was in a fast dive.
     
  16. Apr 17, 2019 #106

    Crawf56

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    Sorry about the crash. Maybe time to put some RC gear in the remaining Shuttle?
     
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  17. Apr 18, 2019 #107

    aerostadt

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    Actually, in a way I have already done something like that. I have a red glider, which is slightly larger than the Double Shuttle glider and has R/C. It has flown twice as a parasite glider on the 4xOT successfully. In fact I have a new 4xOT blue glider that is approaching completion, which has R/C along with in-flight ignition for a model rocket motor.

    My current plan is to rebuild the damaged Double Shuttle glider. I am going to look into finding a lighter nose cone. Also, I want to do a hand-toss test glide of the remaining good glider with higher preset up-elevons.
     

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  18. Apr 24, 2019 #108

    aerostadt

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    I hand tossed the one good glider with a higher pre-set up-elevon and that seemed to help. Since I have a spare nose cone and I need to re-build the damaged glider anyways, I decided to cut off the bottom plate and the rear-end of the old nose cone with my dremel tool and see how things go. While I was doing this I removed some of the mirco-fill of the 3D printed nose cone. However, the micro-fill is so light, this step is probably not necessary. While I was doing this, the nose cone broke. I glued the pieces together with CA and later put epoxy on top of that fix. The nose cone weight went from 2.568 oz to 0.73 oz, which is a 1.838 oz reduction. Overall, I am thinking that this re-build will work. It is definitely worth a try.
     

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  19. Apr 25, 2019 #109

    Rktman

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    Eric Noguchi

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    That's quite a reduction in weight for a glider. Looks promising, I'm with you on a rebuild.
     
  20. Apr 26, 2019 #110

    Crawf56

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    Are you maintaining the same Center of Gravity location? (For boost and glide?)
     
  21. Apr 27, 2019 #111

    aerostadt

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    Crawf,
    In all honesty I have not paid much attention to CG and CP in designing and building this model. Perhaps, I can appeal to using mindsim as I think Daddyisabar would do. Early on I did build a RocSim model to check for stability during ascent. Such a sim model is easy to setup with the two gliders together. I believe RocSim measures the CG and the CP from the nose. On that basis with two E12-4's the prediction is CG=15.74" and the CP=21.56" giving a margin of 1.88. From experience the Double Shuttle flies straight up with no problem. I just checked the undamaged glider for CG, which was easy because it has the launch lugs. So I just put a wooden dowel through the lugs and suspended the model with a string. I don't have a burnt-out E12 (they are too stinky to keep in the house), so I put in a burnt-out AT single use 24 mm motor. I got a CG=16", which is essentially the same thing as before with motors loaded. I am not sure how accurate that is,because I would have expected the CG to have shifted more forward with a burnt-out motor.
     
    Last edited: Apr 27, 2019
  22. Apr 27, 2019 #112

    Crawf56

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    Really good answer. ;)

    I build kits most of the time, so I am targeting recommended guidelines. But when developing a model, so much of the analysis is simply based on observations of performance.
     
  23. May 8, 2019 #113

    aerostadt

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    I tried the Double Shuttle last Saturday. Both E12-4's fired successfully with Blackjack e-matches. However, the gliders failed to separate and there was a hard landing. Amazingly, damage to the gliders is small and the gliders are easily repairable. I still have two E12-4's left, so another try is warranted.

     

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  24. May 8, 2019 #114

    Rktman

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    Eric Noguchi

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    Ouch! Did the ejection charges not go off? I don't think I heard them.
     
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  25. May 9, 2019 #115

    aerostadt

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    Rktman,
    I didn't hear the ejection charges, either. I went back and looked at my original copy of the 05/05/2019 launch. It looks like ignition is at about 5 or 6 seconds into the video and apogee is at about 11 or 12 seconds. So, remembering that an E12-4 burns for about 2 seconds and then the delay is about 4 seconds, there should have been enough time for the ejection charge to go off near or after apogee. It looks like the white smoke on boost stops after about 2 seconds, so I am thinking that was burn-out. Both motors were burnt-out and the Double Shuttle would not get that high without both motors. At the crash scene the gliders would actually apart, but very close to each other. When I think back about past Double Shuttle flights, this has happened several times before. I don't think that BP ejection charges fail very often, if ever, if the thrust producing part of the burn is alright. I now tend to think that the ejection charges fired (the inside vent tubes look like they had a lot soot), but the gliders did not separate. Perhaps, the gliders were too tight together or there is some gas leakage somewhere.
     

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