Giant swing wing!

Discussion in 'Rocket Boosted Gliders' started by Maxout, Nov 15, 2018.

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  1. Nov 15, 2018 #1

    Maxout

    Maxout

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    I built this cute rocket glider a while back, and it flew nicely:


    I liked it, so I decided to throw common sense to the wind and build a bigger one. See the photos below. 29mm fiberglass motor tube from Mach 1 Rocketry.

    Root chord is 10.4", with a 3/8" thick sheet balsa wing for 3.5% airfoil thickness (probably a little on the thin side).
    Still yet to arrive is a fiberglass nosecone (can't use plastic as the captive nose mount would cause the nose cone to melt from the ejection charge).
    Tailboom will be a 1/4" carbon arrow shaft.
    Wing area is about 500 sq in. Oh yeah.
    Trying to keep the weight under 16 oz. I'm a little worried about that bit because I'd like to have a 5:1 mean thrust/weight ratio. We shall see...
     

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  2. Nov 15, 2018 #2

    aerostadt

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    Wow! Interesting! Will be fun to see how this develops and flies.
     
  3. Nov 15, 2018 #3

    Crawf56

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    Winner, winner; chicken dinner.

    While the model is larger, it will allow you to use standard RC receiver and servos, right?
     
  4. Nov 19, 2018 #4

    Maxout

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    Got a little more done on it including the kevlar dihedral hinges. This thing is absolutely massive!

    And a silly sleep deprived video:


    Free flight only this time. R/C would be a piece of cake, but I want the NAR free flight record. ;)
     

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  5. Nov 20, 2018 #5

    Crawf56

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    "Lock S-foils in attack position."
     
  6. Nov 20, 2018 #6

    Maxout

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    For sure!

    I made some more progress. Ok, a lot more progress. Wing outlines are cut to shape, tail sanded and installed, and wing dihedral bevels cut. Hopefully I'll finish it off tomorrow and be ready for a test flight. My launch railing came in yesterday, so I have something to stabilize it up to speed.

    Now is where it gets scary. This model is 21 oz as it stands here. It's probably going to lose weight when I airfoil the wings, even taking into account adding the nosecone and release mechanism, so it's the heaviest now that it could possibly be. The problem is there's no way this thing is dropping under 1 lb, and I still haven't balanced it. If it doesn't require any ballast, there's a chance for a takeoff weight of 21 oz (F15-4 weighs 2 oz loaded), but it could go over, and that's really marginal. I think I can get away with just rigging a piston launcher to accelerate the model faster, but another alternative is to tape a C6-0 to the motor pod and cluster it. It would stay well within the 80 N-s limit even then. Another alternative is to see if someone at next weekend's launch has a F20 or F22 on hand. Time will tell. Weather permitting I'm going to maiden it at our house in a few days, and that leaves me firmly stuck with the F15 platform. This could get interesting. :eek:
     

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  7. Nov 20, 2018 #7

    burkefj

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    Maybe a D to a D chad staged might do it....I know I fly my 5" diameter foam structure pershing on F-32's, it weighs about 22 ounces and it goes about 400' at least, this should not be so draggy and those 24mm motors are pretty light....I also fly my Tri-ceptor trident styled rocket which is pretty draggy on F-32's as well to about the same altitude with 24 oz rtf....I think they are around 60ns maybe.
     
  8. Nov 20, 2018 #8

    neil_w

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    If you ever decommission that thing it looks like you could repurpose the wings as ceiling fan blades. That thing is *big*. :eek:

    Looking really impressive, good luck with the flight!
     
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  9. Nov 21, 2018 #9

    Maxout

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    I got both wings planed out last night, and the right one completely finished. There's 1.6 oz of shavings, all from a single wing, in the first photo (and I planed a little more after that)

    Second photo is the finished right wing atop the as yet unsanded left wing, showing the dihedral tensioner.

    It's now 3.5-4 oz lighter than before. I should have it finished up tonight, since all I need to do is sand that left wing, install the locking mechanism/nose, and add rail buttons. Oh, and make a piston so it actually clears the rail at a safe speed. I'll coat the top of the right wing with a thin layer of epoxy as a heat shield before launching it, but for now I need to get it balanced for a stable glide.
     

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  10. Nov 21, 2018 #10

    aerostadt

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    How thick is that balsa wing?
     
  11. Nov 21, 2018 #11

    Maxout

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    3/8" at the root. I kept it that thick at the high point out to 1/2 span and tapered it from there.
     
  12. Nov 26, 2018 #12

    Maxout

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    The maiden flight did not go well. The launch piston absolutely disintegrated, but that was relatively ok since the launch was safe. What wasn't safe was that the right wing failed to deploy. This is my first failed deployment probably ever, since I can't remember ever having one of these crash from anything other than structural failure in flight. First time for everything...

    I was a bit dejected, but all the parts were there save for the nose cone which was absolutely smashed. Basically, it just rekitted itself. Ok, there was a kevlar hinge that got shredded, too...

    I put it back together, and everything seemed to function well. In glide testing I ended up taking off all of the nose weight to get a happy glide. This was rather alarming, since it put the CG aft of 50% root chord. I've never flown one of these with the CG aft of 35%. Still, it seemed really happy, so who was I to argue?
     

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  13. Nov 26, 2018 #13

    Maxout

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    I posted this excited photo on Facebook on Saturday, right before the adrenaline drained out of me and I found myself absolutely exhausted...

    None of that exhaustion mattered...

    At GRITS 2018 on 24 November 2018, Fliplock F left the pad on its first public flight, powered by an Estes F15-4. It performed flawlessly in every way, milking every second out of the damp air for a total flight time of 75 seconds, which establishes a new NAR record in F Rocket Glider.

    Here is a complete video roundup of the project, including the record setting flight:




    So where to from here? Well, this model will be mothballed for a few months while I concentrate on other projects which have been delayed because of it. When I get a feel for dates for the next nearby NAR launch at a sufficiently big field, I'll work on fiberglass shielding of key areas of the airframe as well as investigating ways to reinforce it for more powerful motors. Options include testing to see if an Apogee F10-4 will be strong enough to lift it (lighter than an F15, and 60% more total impulse for a massive 8.5 second total burn) or exploring the necessary reinforcing to withstand an Aerotech F25 (same 60% impulse increase, but only a 3 second burn, so extremely energetic and rather dangerous to the airframe).


    The G record is going to be much harder. The G12 would work, but I'll have to use altimeter-activated deployment since those are plugged motors. Altitude would be absolutely spectacular, that's for sure. G38s are almost out of the question. That's 3 seconds of power spent mostly at >5:1 thrust to weight ratio. Gonna be hard to survive that. Alternatively, I could cheat my way into G impulse by launching on an F10 clustered with an Estes C6-0. Time will tell which one wins...
     

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  14. Nov 26, 2018 #14

    burkefj

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    Nice straight boost and perfect trim, and the thrust profile looked excellent for that model, congrats!
     
  15. Nov 26, 2018 #15

    Crawf56

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    Well done, sir! The glide performance was spectacular, especially the way it recovered from the stall. :cool::cool::cool:

    Would be very curious to see how the model would perform with a shorter ejection charge delay, or even with a boost engine (if these are options).
     
  16. Nov 27, 2018 #16

    Buckaroo

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    Congratulations on an impressive accomplishment. I got to watch this flight and it was fantastic to see. If I remember right, the glider was pretty nose down by the time the wings fully deployed and you lost quite a bit of altitude before it leveled out? I can only imagine how much longer it would have stayed in the air with an earlier deployment, maybe a 2 second delay? Either way it was fun to watch. Maybe a CTI F29 IMAX with a 3 second delay? Or how about the G33 Mellow? Not sure which was more impressive, the big bird or the MMX one. Well done sir!
     
  17. Nov 27, 2018 #17

    Maxout

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    One of the problems with picking motors is dealing with the NAR motor certification list. I'd love to launch this thing on any one of several nice options out there for long burn motors, but NAR hasn't certified them for whatever reason. Based on my current research, I'm considering the Apogee F10 for the next time I get this bird to a big field. It's got a lower average thrust, but stays above 15N for a full 1 second. Definitely a calm-day-only setup, though, although I could strap a B6-0 to the side for an extra shove.

    For a G powered launch, there are several approaches given that this model can crack the G record without even trying just so long as it survives launch. One is that F10 again, with a C6-0 strapped to the side to push it over the 80 N-s threshold.

    Of course, the G25W-10 is an option provided that the delay drilling tool can be used to shorten that back to 4 seconds. Can anyone confirm that this is allowed for NAR contest flying and that the G25W reloads can have their delays drilled back?
     
  18. Nov 27, 2018 #18

    burkefj

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    The G-25 is pretty robust and weighs 5.5 oz I think rtf, I flew that in my big X-15 that weighed around 37 ounces and boost was pretty quick, in this model it might be too much. the G-12 32mm motor would be better, it weighs 4.5 oz rtf...you'd have to swap your forward pod, but using a double thick BT-56 would same some nose weight up front anyway and might be a decent trade off but as you said you'd need to figure out a deployment scheme since no ejection...are you allowed to use an altimeter ejection for free flight rocket gliders? that wouldn't add a significant weight to something this size, and you could also use the single use G-12 if gary can get it re-certified with the temp under control.
     
    Last edited: Nov 27, 2018
  19. Nov 27, 2018 #19

    neil_w

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    What's the current G record?
     
  20. Nov 27, 2018 #20

    burkefj

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    http://www.nar.org/records/
    Rule Div Impulse Event Record Date Set Holder NAR Num Motor(s)
    35 C 1/8A RG 49s 8/25/2007 Chan Stevens 80019
    35 C 1/4A RG 68s 4/15/2000 David Schaefer 62840
    35 C 1/2A RG 230s 5/17/1981 Lawrance W. Bercini 18121
    35 C A RG 750s 10/10/1981 Martin Huber 29714
    35 C B RG 276s 9/16/1995 Andy Jackson 14575
    35 C C RG 361s 1/28/2015 Vern Richardson 91272 C6-3
    35 C D RG 361s 8/6/1987 Dan Domina 45463
    35 C E RG 951s 9/26/1993 Fred Williams 14198
    35 C F RG 54s 5/30/2004 James N. Brazell 12442(former F record)
    35 C G RG 56s 5/30/2004 James N. Brazell 12442(current G record)
     
  21. Nov 27, 2018 #21

    neil_w

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    Wow, that E record... Thermals are a beautiful thing.... sometimes.
     
  22. Nov 27, 2018 #22

    Maxout

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    Frank,

    Thanks for that info. I was really hoping to avoid that 36/60 casing. I guess not...
     
  23. Nov 27, 2018 #23

    BigRiJoe

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  24. Nov 28, 2018 #24

    Maxout

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    Yes. The hosting club, SOAR, was kind enough to put in a contest sanction for this launch.
     
  25. Nov 28, 2018 #25

    Tyler P

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    That was awesome! Very cool design! Congrats!
     
  26. Dec 6, 2018 #26

    Maxout

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    I've ordered some Apogee F10-4 motors for this rascal. Comparing the F10 thrust profile to that of the F15, I find that the F10 actually stays above 15 N longer than the F15, and follows that up with a heck of a long burn, remaining around 9 N for the remainder, which is enough to keep it pointing up for the remainder. The impulse being 74.3 N-s, I'm going to slap a B6-0 on the side for some extra oomph on takeoff.

    This sets the stage of course for my next hat trick which is that as soon as that flight is over, I'm going to load back up and put a C6-0 in that side pod to push it into G class and go after that record while I'm at it. Given the long burn and lower percentage of total time before deploy spent nose down waiting for the ejection charge, I'd be willing to bet it does close to 3 minutes in both configurations. More if there's any lift. And if it's windy, well, we're not flying, even though I've launched this thing in 15 mph winds without it weathercocking on the F15.
     
  27. Dec 7, 2018 #27

    Amsterdam

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    Congratulations on the record! And Congratulations on the 1/8a record!

    Ever get the urge to combine all your aeromodelling skills into one da Vinci-stein contraption?

    Like a rocket boosted rubber plane, maybe a scissor flop wing, folded prop, all tied up with a burn string?
     
  28. Dec 9, 2018 at 11:33 AM #28

    sooner.boomer

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    Just catching up on this thread. Braz was a friend of mine. He was a forum member for a few months before his very untimely death. I assume he made these records with a version of his BORG (Big Ol' Rocket Glider), a delta-winged, canarded glider made from thick foam poster board.

    951 seconds! Wow! That's almost 16 MINUTES of flight time!
     
  29. Dec 10, 2018 at 3:04 PM #29

    Maxout

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    Could be fun, sans burn string. Burn strings are against my...well...my everything. I built two models with them long ago and divorced myself from that technique as quickly as possible. ;)

    Sounds familar. I've got a video of that model's record flight archived somewhere (no, I wasn't present for the launch). The announcer said it was called "Reptilian Entity". Your description is definitely consistent with the layout of the model.

    One of the R/C records is nearly an hour. All you need is a good thermal. PD was won this year with a 30 minute flight. And quite frankly an optimized F or G sized glider should do over 10 minutes in dead air. Molded carbon S8E models are getting 10 minutes in dead air. Admittedly, that's a $1000 airframe, but the point remains.
     

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