Sea Tiger

Discussion in 'Low Power Rocketry (LPR)' started by Bruiser, Jul 12, 2019.

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  1. Jul 12, 2019 #1

    Bruiser

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    Having finished my latest design (Tempest in the multi stage forum) I have been deciding what to build next. I have been thinking about picking back up a project that stalled or building an upscale Shrox design. Earlier today I gave up on finding a file for one of the Shrox designs that I liked and I started working up my own design inspired by the Shrox's designs.

    I am calling it the Sea Tiger. It's BT60 sized, just under 24 inches long and has a 24mm motor mount.

    My build should start tomorrow. I'm very excited!

    BTW, the engine pod under the body tube is the "scale" location. The mount is in the main body tube.

    Sea Tiger 2.JPG

    -Bob
     
  2. Jul 12, 2019 #2

    kuririn

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    Looks like a sea borne cruise missile. What's up with the naval designs? Are you a Navy vet by chance?
     
  3. Jul 12, 2019 #3

    BABAR

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    Cool!
    Gonna put a motor in the pod and cluster it?
     
  4. Jul 12, 2019 #4

    Bruiser

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    What's up with the naval designs?
    I don't know. I didn't even realize it until you mentioned it. Maybe I've been listening to the Village People too much lately :)

    Are you a Navy vet by chance?
    No, I'm actually retires Air Force. Almost joined the Navy though right out of high school but the recruiter pushed too hard and spooked me :)

    Gonna put a motor in the pod and cluster it?
    No, but it was tempting. I've read up on offset thrust lines and such but I am going to save that for when I build the Interceptor with the booster :)

    -Bob
     
  5. Jul 12, 2019 #5

    BABAR

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    That minimal an offset isn't much of a problem, in my experience. That's my routine with long gap stage rockets.

    It's when you put motors in pods at the outside edges of the fins that you get into trouble.

    Problem with your design (if you cluster) is the open forward end of the tube. Best be would be plug the tube forward of the tube and eject the motor, use zero or short delay (best bet, even a zero delay motor should eject and that's less mass slowing down the rocket, dumps it on the upward trip before the main engine deploys the chute).

    If you use a long delay and deploys AFTER the main deploys the chute, could potentially get "interesting."

    "interesting" is generally not a good thing in this scenario.
     
  6. Jul 13, 2019 #6

    Bruiser

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    I'm not going to cluster or stage this one. Once I graduate to electronics I will probably stage this:
    Estes Interceptor with Booster Page.PNG

    In the meanwhile, I'll just plug away at my simpler models.

    I bought the motor mount today. I made the centering rings from a couple layers of poster board and I bent up a motor retention spring thingy

    I also cut out the wings and fins. I papered them with Avery label paper.

    I filled and sanded the spirals on the main body tube.

    I built the "engine pod" and have it ready to primer.

    I also made a "coupler" from a couple layers of poster board. It' not going to be used as a coupler though. It will be a ejection baffle instead.

    Sorry no pics. I'll get some Monday.

    -Bob
     
  7. Jul 13, 2019 #7

    kuririn

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    This actually looks more interesting than the Tarmon. I see you've replaced the big ventral fin with the faux motor tube. Will be looking forward to this build.
     
  8. Jul 13, 2019 #8

    Bruiser

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    I went to the Space Museum yesterday to look at the Lance on display, but that's another thread. While I was there I noticed this rocket.
    XQ 4A.jpg


    I had already been thinking off designing something like the Tarmon, Sea Snap or DetlanX. When I saw this display, I decided my design would have a engine pod like this.

    -Bob
     
  9. Jul 15, 2019 at 1:17 AM #9

    BABAR

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    The pic makes it LOOK like there is a big CHAD staged Estes cardboard motor in the pod!
     
  10. Jul 15, 2019 at 2:11 AM #10

    Bruiser

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    The front looks just like the back. I thought about some sort of boat tail on my rocket but the CP and CG were just right without one. If I had added a chopped off nose cone back there I am sure I would have needed more weight up front.

    Some of these type of drones/test rockets had both a rocket motor and some sort of jet engine. The rocket motor would fire to help get it up to speed then the same jet engine would take over flying it.

    -Bob
     
  11. Jul 15, 2019 at 8:58 PM #11

    Bruiser

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    I have glued in the motor mount and the baffle. I didn't take pictures of the mount but here's the baffle:
    Sea Tiger Baffle A.jpg
    Sea Tiger Baffle B.jpg


    I also have the fins on and am working on the fillets now.
    Sea Tiger Fins On.jpg

    -Bob
     
  12. Jul 15, 2019 at 9:57 PM #12

    neil_w

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    In the current design it appears as if the rocket has no fin area extending below the rocket, although it's hard to tell exactly what's going on with the tail there. You will have the pod hanging down there, though I haven't figured out from discussion above whether it'll be open or closed (or if it's long like the photo it may *behave* like it's closed; that's pretty long and skinny for a tube fin. Either way I suppose the pod will pull the CP down a bit, maybe not too much different from a fin (depending on final shape).

    I'm never quite sure how much of a problem this might be. The good old Estes Firecat has only a pod hanging down, but it is short and open and should be functioning as a pretty effective tube fin.

    Just pondering.
     
  13. Jul 15, 2019 at 10:22 PM #13

    Bruiser

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    The pod is open. The lower fins are not 90 off the vertical but they aren't at 120 degrees either. I haven't gotten out a protractor but I would say they are at maybe 110 degrees. It's all good :)

    Sea Tiger Rear.jpg

    BABAR wants me to put an engine in the pod but not on this design :) It's a flow-thru pod

    -Bob
     
    Nytrunner and neil_w like this.
  14. Jul 17, 2019 at 5:36 PM #14

    Bruiser

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    No naked rockets. Got the primer on. Now I need to lock in the final paint scheme.

    Sea Tiger Primer.jpg

    -Bob
     
  15. Jul 17, 2019 at 6:00 PM #15

    neil_w

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    The paint scheme in that rocket in the photo from the Space Museum you posted looked pretty sharp....
     
  16. Jul 17, 2019 at 8:47 PM #16

    BABAR

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    You have plenty of fin surface area. The asymmetry should not cause instability ( net trajectory will be straight)
    You may get a bit of spiraling.

    Your open tube may be too long relative to diameter to function as a tube FIN but the base drag will also help keep net trajectory straight.

    I predict this will be a good flyer as well as a show model.
     
  17. Jul 17, 2019 at 8:54 PM #17

    neil_w

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    Thanks, I am terrible at mind-simming asymmetrical designs.
     
  18. Jul 17, 2019 at 9:10 PM #18

    kuririn

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    Is that 3D rendering in the first post from an OR file?
     
  19. Jul 18, 2019 at 1:53 AM #19

    Bruiser

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    "The paint scheme in that rocket in the photo from the Space Museum you posted looked pretty sharp.... "
    I like it too but I will build a scale model of that one someday so I have to save it. I had the mechanics of this scheme picked out but not the colors. I will say that the paint gods frowned on me today. I painted the belly and it came out good. I had a small build up on the tail of the engine pod from trying to spray inside the tube but it'll be ok. Then I went to paint the tail fin blue and the paint had a weird reaction. It kinda of puckered up and then settled into a sort-of stucco/sandpaper look. I thought maybe I had something on the fin so I sprayed a piece of metal laying around and it did the same thing. Then I shook the hell out of the can and tried again, same thing. I guess it's going in the trash... Rustoleum 2X Gloss Blue, the medium shade.

    "I predict this will be a good flyer as well as a show model. "
    I hope so, thanks for saying that. The fins were to be set at 120 degrees then last minute I decided to kick them up just a little. Truthfully they came out a little "flatter" than I meant for them to.

    "Thanks, I am terrible at mind-simming asymmetrical designs. "
    Me too. I went with the TLAR method and actually went a bit beyond TLAR. When that happened, I switched over to the "build it and it will fly" theory from Field of Dreams. Never underestimate the power of positive thinking :)

    "Is that 3D rendering in the first post from an OR file? "
    It is an OR file. I stuck pretty close to it during the build. Wanna see it? I've attached it if you do.

    -Bob
     

    Attached Files:

  20. Jul 18, 2019 at 7:05 AM #20

    kuririn

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    Simmed it with a C11-5. Around 470ish ft. Looks like a good small field flyer.
    I see your D12 and E12 sims.
    Looking forward to your flight report.
     
  21. Jul 18, 2019 at 2:20 PM #21

    BABAR

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    Wow I didn't know the fat 24 mm C engines were available again. Good to know.

    https://www.acsupplyco.com/estes/engines.htm
     
  22. Jul 18, 2019 at 2:25 PM #22

    neil_w

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    I didn't know that either. Good news! I always like to use these for first flights on my 24mm rockets.
     
  23. Jul 18, 2019 at 2:37 PM #23

    Bruiser

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    I tend to build my rocket around engines that are available locally so this one will go with a D12-5 to start with. Hobby lobby doesn't carry the C11, at least the local one here does not.

    I didn't even know about the C11 until I went on the Estes site and ordered a pack of A8-5 for the sustainer of my Tempest design. Hobby Lobby has discontinued the D12-0 engines but I bought the last few packages they had. Maybe they are bringing in the C11 series of engines. I hope they do bring in some type of 24mm booster.

    I believe the local launch is scheduled for this Saturday. I think I will launch either my heavily modified Estes Honest John or my scratch built Nike 10 Degree Heat Test rocket. They are both 24mm and are ready to go. My Tempest is also ready to go but I don't think the A8-5 engines will arrive in time.

    I think I will have this one (Sea Tiger) done for next month's launch. I'm in the paint phase now and that just takes time. You can't rush Rustoleum products. I sprayed the first color yesterday so I have to wait another day before I can mask it off for the second color. If the second color goes well, I'll be able to spray the third color Monday. I did try to speed things up by painting the "rudder" yesterday as well, but that paint had some type of reaction coming out of the can so I need to sand it and try again :(

    -Bob
     
  24. Jul 18, 2019 at 5:12 PM #24

    Bruiser

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    Here is how the rudder turned out. When I first sprayed it on, it reminded me of crinkle paint like you might use on engine valve covers but it laid down flatter as it dried. Now it looks like drywall texture...
    Sea Tiger Rudder Texture.jpg

    This is Rustoleum American Accents 2X Ultra Cover Gloss Brilliant Blue. I need to figure out how to contact Rustoleum customer service for this one...

    -Bob
     
  25. Jul 18, 2019 at 7:56 PM #25

    BABAR

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  26. Jul 18, 2019 at 8:24 PM #26

    Bruiser

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    Rustoleum's Reply


    What you are experiencing sounds very much like dryspray.
    This is when the paint mist from the aerosol can dries in the air and lands on the painted surface.
    Where this 'dryspray' or 'overspray' lands it prevents the coating from leveling out properly and can leave a dull or textured finish.

    Factors that can cause dryspray or overspray include:
    - Painting in direct sunlight or in very warm or windy conditions
    - Holding the can too far away from the surface or at an uneven distance while spraying
    - Painting large, flat surfaces or intricate objects with a lot of open space
    - Painting multiple objects next to each other

    I spray in a connex so no wind or direct sunlight but it may have been warmer than 90 degrees yesterday

    I hold the can about 12" from the item

    The fin is small, 2.5 x 3 inches

    It was the only item I was painting

    BTW, I tried the can again this morning on some scrap laying around and it seemed good. I taped up the fin and sprayed it and guess what? yep, the same thing. It's all sanded off now and it is now in gray primer. There is blue paint residue all over the rest of the primer. I even got some on the area that was "final" painted. I haven't messed with trying to get it off that yet. I don't think I am going to do this blue again. I think the "rudder" will be another blah color. So much for adding some "splash"!

    Update, I was able to get most of blue smudges off the "final" paint. I think I will be wet sanding this one and spraying a clear coat over it so that will get rid of any blue that is left behind. If not, re-spray...

    -Bob
     
    Last edited: Jul 18, 2019 at 8:32 PM
  27. Jul 18, 2019 at 8:42 PM #27

    Nytrunner

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    I do believe the C11 will be back. If it is, goes to show that new Estes leadership listens to the people of the hobby

    At NARAM 60, one of the first things Ellis Langford was asked at vendor forum was "Why did you get rid of the C11?/When are you bringing back the C11?"
     
  28. Jul 19, 2019 at 2:59 PM #28

    Bruiser

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    So I think this is where Rustoleum and I part ways.
    Sea Tiger Gray Splatter.jpg

    Pretty much the same results as with the blue. I think I am going to another brand of paint after this rocket. After this dries I'll try wet sanding it with some 1,000 and see what happens. If I can get it smooth enough without punching thru I will clear coat over it. Chances are that I am going to end up repainting...

    I like the Duplicolor "color match" paints but the color selection is somewhat limited for scale projects. Autozone has the best selection in my area. The other problem is paint adhesion to plastic but they do make a promoter.

    I am thinking about the Model Master paints at Hobby Lobby. Our HL just doesn't have a very large selection in the store.

    I think I need to look on Amazon...

    -Bob
     
  29. Jul 19, 2019 at 3:12 PM #29

    Nytrunner

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    How long are you waiting between recoat? And what's the humidity in your area?
     
  30. Jul 19, 2019 at 3:18 PM #30

    BABAR

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    Whatever paint you use next might be smart to try it on a scrap piece before you try it on your rocket. Scrap piece should Scrap piece should however be prepped the same as The rocket is already prepped, including sanding and primer
     

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