X-20 Dyna-Soar with titan booster....

Discussion in 'Rocket Boosted Gliders' started by burkefj, Nov 3, 2014.

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  1. Nov 3, 2014 #1

    burkefj

    burkefj

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    I've been wanting to try adapting my already flown X-20 dynasoar to a titan booster. The X-20 is 11 oz rtf with a 24mm E-6 motor, 9 oz rtf without motor, it is 30" long and 20" wingspan, made of 3mm and 6mm depron, and approx 4" diameter. Booster will be 8" diameter.

    It's very lightly constructed so I can't just slap it onto a normal rocket booster and fly it on high impulse motors or it will come apart. My though is to construct a large booster using model airplane construction, depron centering rings, carbon spar depron fins, 6mm depron stringers between the centering rings, a 29mm tube up the middle for support and a 2mm depron skin.

    I'm planning on having the chute in a 4" compartment under the dyna soar with a capped coupler as a nose cone, and on ejection pop the glider off and deploy the chute and have it come nose down. Glider will attach via three carbon rods and aluminum guide tubes.

    It's going to be very tough to keep the weight down, I've got a spreadsheet and am counting ounces already. It may turn out to be a complete failure, either over weight or not stiff enough, but if it works it will open up some other large designs I want to do that can fly on smaller motors.

    If all else, it may bring you all some laughs.

    here we go, rear centering ring and depron rings cut and the fins cut out. Should be around 110" long and be based on a photo I have, but since these were all concepts, i'm not going to get too hung up on scale.

    Idea is to have the centering rings about 8" apart with 1" stringers, between each centering ring at the outer circumference and have 8 stringers around. This will give extra surface area to contact cement the 2mm skins to and help with stiffness.

    Here are some simulations.

    Frank

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    Last edited: May 27, 2015
  2. Nov 3, 2014 #2

    TheTellurian

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  3. Nov 3, 2014 #3

    burkefj

    burkefj

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    Did a bit of work trying to figure out a solid mechanism to attach the guide rods....Here's the idea, two at the wing/fuse roots and probably another into the upper part of the shroud and attached to the 4" parachute bay, not shown yet....

    Frank

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  4. Nov 3, 2014 #4

    burkefj

    burkefj

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    a bit more progress, mounted the rod guides, added a third locating guide near the top of the model....seems like it slides off ok, a lot can go wrong, ejection might not push the model squarely, so it might cant on the rods, blocking chute from coming out.....

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  5. Nov 3, 2014 #5

    burkefj

    burkefj

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    Did some ground testing. I created a cap for the parachute bay, that seemed to work well, and also manually blowing on the tube forced the cap and glider out as long as there wasn't significant horizontal load on the glider. These were done holding the glider horizontal which should be the worst sort of loading on the guide rods to cause binding. I need to figure out how to mount the altimiter in a place I can get to it, and then start on the fuse.

    Frank
     
    Last edited: May 27, 2015
  6. Nov 3, 2014 #6

    Rob Campbell

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    This is going to be good!

    :pop:
     
  7. Nov 4, 2014 #7

    burkefj

    burkefj

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    Some more progress, I mounted the av bay hanging below the upper ply plate, I'll have a hatch allowing me to load the altimiter and route the deployment charge up into the parachute cup...
    I also added a ply plate on the centering ring to attach the upper rail button.

    Started adding the depron centering rings, and the stringers, about 2/3 done, then reinforce the joints, and put on some skin. It's got a slight bit of flex right now, but with the skin attached to the stringers it should stiffen it up.

    Weight of the unit so far with glider attached and altimiter is 29 oz.

    Rest of the components, skin, fins, chute, and rest of the centering rings add up 24 oz.

    I may need to run motor ejection as backup in case it pitches over and doesn't reach 200 foot arming altitude.....

    Also, if it did pitch I'm assuming I'd need to give opposite controls since it would be more like a canard...

    Frank

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    Last edited: Nov 4, 2014
  8. Nov 4, 2014 #8

    burkefj

    burkefj

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    Major milestone, got the first skin on, went on ok and really added stiffness. Cut the door for the av bay. Hard part now is to make the fin box and make sure they are perfectly straight and aligned with the dyna-soar wings....

    Frank

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  9. Nov 4, 2014 #9

    shrox

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    I am sure it will be just as awesome as you envision.
     
  10. Nov 4, 2014 #10

    Daddyisabar

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    This is super cool!
     
  11. Nov 4, 2014 #11

    burkefj

    burkefj

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    Did a bit of work on the fairing, a lot of cutting paper, fitting and then seeing how the foam bends and adjust as needed.
    Also built one of each fin, with a single carbon spar and 2 6mm sheets laminated, so I could get a weight, 2.4 oz for the large fin and 1.75 for the smaller fin.

    You can see the door to the electronics below the transition.

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    Last edited: Nov 14, 2014
  12. Nov 4, 2014 #12

    burkefj

    burkefj

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    To give an idea of how light this is, the entire rocket plus glider at 110" long and 8" diameter will weigh the same as 70" of standard loc 7.5" tubing with nothing else, just the tube...
     
    Last edited: Jun 18, 2016
  13. Nov 5, 2014 #13

    burkefj

    burkefj

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    Made some fin guide templates to hold the rear and align the fins so I could build the fin boxes straight, and also to hold the dynasoar wings level so that the fins are aligned with the wings. Worked well, created the fin boxes, locked them together with a second gusset so that bending loads would transfer to the other fin boxes and not rely on glue joints. Skinned the rear section and cut out the fin slots afterward. Looking more and more like i imagined. It's gotten so long I had to do the fin alignment in the garage, the kitchen counter is 8' but that's not enough....Need to build the other two fins, finish the transition skinning and then do some rail buttons.....and add the bottom centering ring, retainer and eye bolt.

    Frank

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  14. Nov 5, 2014 #14

    burkefj

    burkefj

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    Right at 59 ounces now with everything installed less motor, and less the final fairing pieces, looks like 60 oz will be the auw dry plus any balast. Wings/fins appear aligned nicely.


    Frank
     
    Last edited: Nov 14, 2014
  15. Nov 5, 2014 #15

    aerostadt

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    The model looks terrific, Frank, and the low weight is amazing. I remember years ago someone built a Restone Mercury that was very light; I think using 1/64" ply. The center tube is amazingly a small diameter. I would think packing a parachute in there would be a challenge, but since the overall model is so light, you have probably already sized the parachute appropriately. I am also surprised that you do not need any lead in the forward end in order to move the C.G., but it sounds like you have already checked and simmed that concern. The detail on your X-20 with the fine white lines looks terrific. On a different note I have gotten my order of Depron to build your SR-71 profile model (foamie), but I have not taken it out of the box, yet. I will PM you, when I start making progress on that project.
     
  16. Nov 5, 2014 #16

    burkefj

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    Thank you. For the chute, it will go into the 4" upper tube that has the piston/cap to blow off the glider, so there is 5" by 4" of room, plenty for a blanket or two, kevlar and a 48" chute, at 58 oz recovery weight, that should be plenty of chute. This is the same size I used in my flown full scale Hellfire that is slightly heavier.

    Frank
     
    Last edited: May 27, 2015
  17. Nov 6, 2014 #17

    burkefj

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    Finished the transition, painted it and all up weight is now at 61.5 oz. CG is where I think it needs to be. Added magnets for the electronics door. Will also tape it for flight to keep it from popping open due to aerodynamic forces.

    One question I have though, the X-20 I built was based on a version with canted outboard fins...on the glider flying by itself, this will help lateral stability, like a shuttlecock, trying to keep the rear end behind the nose due to the drag....Now that it is mounted on the nose, what will that do? Will it have the same impact, or will that drag tend to want to destabilize the booster......should I build one with straight outboard fins? I've tried to model this with side by side fins in the middle of the rocket both canted at opposite angles, and with a transition wider than the body tube by a few inches(like a shuttlecock), I see it move the CP forward.... but I don't know if that will be modeled correctly....

    Frank

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  18. Nov 6, 2014 #18

    chuck5395

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    Wow Frank. Wow!
    Can't wait to see this baby in action.
     
  19. Nov 7, 2014 #19

    burkefj

    burkefj

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    Well, this afternoon I met my buddy John at the Evergreen Museum in Mcminnville and we met James Barrowman, yes that one.....and got to take an after hours tour of the museum, and got to sit in the pilot seat of the spruce goose....! James is a great guy, and I even asked him about my angled fins on the X-20 and he thought I could model them with straight fins to first order.....that was neat to meet him.

    Frank
     
  20. Nov 7, 2014 #20

    TheAviator

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    Looking awesome. <4 pounds at that size is an excellent weight for that size. Can't wait for the flight report.
     
  21. Nov 8, 2014 #21

    burkefj

    burkefj

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    I decided yesterday to build a second Dyna-Soar, with the wing tips not swept out quite as much, in addition I could build in a pixie 7 amp speed control to fire onboard ignition if I decide to do that. I made a few changes, used 2mm depron instead of 3mm sheet for the fuse, cut some lightening holes in the 6mm fuse spine. Managed to cut an ounce or so from the original weight. I'm using a single 120 2s battery for radio if it is glide only, and a 2s 800mah pack for flight standalone with the E-6. I'm not going to set it up for airstart yet, there is enough to go wrong as it is....

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  22. Nov 9, 2014 #22

    burkefj

    burkefj

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    Had some leftover vinyl from my Titan II so I started applying some to the Booster, I don't want to paint it to save weight, but I will do the stars/bars and us air force and cutouts for the stage separation.

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  23. Nov 9, 2014 #23

    burkefj

    burkefj

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    Here is the new glider, also put in a few carbon strips on the inboard and outboard trailing edge tips of the booster fins to protect for landing impact, I also inserted and glued two 3/16" carbon rods in the rear centering ring to protect the inboard fin tips from landing impact as well.

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  24. Nov 9, 2014 #24

    burkefj

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    I also ran into a slight problem. I had planned on using rail buttons attached to the forward and rear ply centering rings since I had access to them.....However I didn't realize they were about 7 feet apart....and most of our rails are 8 feet long and you need some amount of standoff......I still wanted the forward rail button to give some resistance to wind when the glider is attached and on the pad, so I had to figure out a way of putting another rail button just ahead of the CG. It is mostly foam in that area.

    However what I came up with seemed to work. I cut two 4" by 1/2" 3/32" ply plates and a 1/2" by 1/4" ply block. I glued the 1/4" ply block between the two plates at one end so it made a U shape.....
    I then cut into the fuse skin on either side of a 1/4" foam centering ring. I think slipped the U shaped thingy with the 3/32" ply fingers on either side of the foam ring and up against the motor tube...and glued in place. So there is a glue joint to the motor mount, and on either side of the foam centering ring and into the skin at the surface, it appears to be quite solid...sort of a ply/foam sandwich...here is a crappy drawing....and a picture of a later model that I did this to before skinning...you'll get the idea.


    Frank

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  25. Nov 10, 2014 #25

    tab28682

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    A stellar job on the Titan/Dynasoar stack! Looking forward to the flight report!
     
  26. Nov 14, 2014 #26

    burkefj

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    Got the markings from Mark at Stickershocktoday and as usual were perfect! I've modeled this in openrocket, rocksim, and modeled it as a full wing for the glider, a 4" tube for the glider and wings added, and as just the wings added on to the body tube....all give me a cp that with a few ounces I added and a slighly larger battery in the glider than I need for glide CG give me 1.6 cg to cp margin....the glider is pretty well aligned, it has a slight bit of play so that it will come off the rods, that gives just about 1/16 to 1/8" of offset from the centerline worst case at the front of the glider....hopefully that will not be enough to cause a drastic loop effect....CG is about an inch above the rectangular 2nd stage cutouts...That matches pretty well with what George Gassaway used in his much smaller naram model back in the day. I also proudly stole the markings he used as a template. CP runs roughtly from the
    A to the R in AIR depending on how you model it.

    Frank

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  27. Nov 14, 2014 #27

    aerostadt

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    This looks really cool! I can't wait to see it fly. I'm sure you will have video.
     
  28. Nov 14, 2014 #28

    burkefj

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    Thank you. It's interesting, the CG of the glider and the distance to CG is identical to the motor and distance to it...they weight approx the same, so they balance each other out.

    I'll fly the new glider on it's own to confirm the glide CG, I'm considering flying the booster on it's own just to determine max altitude and make sure ejection works ok, I'm afraid that if there is any contact of the piston and body it might damage the booster and that might prevent a same day flight of the full stack, but is probably worth the risk. The CP without glider is about 1/2 a diameter in front of the fins, and the CG with motor is well ahead of that....so it should fly fine, but it will tell me if there is any roll......

    Frank
     
  29. Dec 16, 2014 #29

    burkefj

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    I did get in some glide trim tests of the new glider I built with less wing tip angle and it flies about the same as the other one. I did figure out how to set my elevon pitch direction to work opposite on boost and switch back to normal pitch direction once in glider only mode, the throw on the boost setting is about 1/4 of full throw due to the mixing, which is probably a good thing.
     
  30. Dec 16, 2014 #30

    Rob Campbell

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    Might try a retract to elevator mix and program in an offset. I did something similar about 12 years ago with a Zagi 400. I had a powered mode and a glide mode. What radio are you using? I'm fairly good with most of the Futaba radios.
     

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