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10" diameter JayHawk

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SMR

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This is my first really big scratch build, and first attempt to document it on the forum. I am building a 10" diameter JayHawk, (roughly 7/8 scale). Estimated launch weight approximately 100 pounds to fly on M1939-W, M2500-T, N2000-W, or N3300-R, depending on final weight. Launch is scheduled for late October at Mid West Power 2010. Special thanks to Andy Woerner for the concept, Jack Garibaldi and Polecat Aerospace for core components, and to Gates Brothers Rocketry for build tips and inspiration. (First launch is for you, Erik.)

JayHawk wing.jpg
 
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stickershock23

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WOW, now that is a project!

Can't wait to see the build. and the flight.

Are you worried at all about the fins? with the "H" tail do you think flutter will be a problem? I ask because I am doing a similar project (at least its "H" tail) and that is my biggest worry right now.

oh by the way I just added these to my website TODAY. havn't even announced them yet. maybe you would be interested..

jayhawk NEW pre.jpg
 

dixontj93060

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SUPER! Let's hope for good weather during harvest and no rescheduling of Midwest Power this year. Nice to see a first big project so soon!
 

SMR

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Last week we worked on the nose cone and canard. I slotted the nose cone, (thank you, Albert Dremel), and cut the slug out of 7-ply 1/2" birch plywood. Next on the agenda is adding a 15° bevel to the leading and trailing edges, and cutting the two custom nose cone bulkheads (8 1/4" and 9 9/16"). The bulkheads sandwich the canard between them, with all-threads extending up to the nose tip to anchor the lead weight to be added prior to launch. The goal is that none of the stress at deployment or landing is carried in the fiberglass shell of the nosecone itself. The bulkheads were a bit challenging, as the edges are tapered, each at a unique angle corresponding to the taper along the Ogive nose cone. I included access holes to pour a slurry of epoxy and #4 lead shot into the tip of the nose to adjust the Cg forward. The nose cone will separate with the drogue parachute after pulling the deployment bags off the main parachutes at 1100'. To protect the nose cone during landing with the added weight, I reinforced it internally with fiberglass tape epoxied along the seams and bulkheads. The interior space will be foamed as a final step, after the Cg is established.

nose cone slotted.png


canard slug.png


canard cut.png


canard bulkheads.png
 
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SMR

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Feb and March were set aside to finish the main wing. This is a big learning experience. The original plan called for building two wings (revision 1 and 2), and deciding after they were completed which I would use (depending on stiffness and weight). I am now on my third. Wing #1 was cut from 3/4" birch plywood and skinned with 1/32" G-10, which would have been its final surface. While examining it's twisting resistance, I managed to delaminate the leading edge, most likely due to inadequate surface prep. (better here than at 5,000'.) Wing #2 was also cut from 3/4" plywood, but skinned with 3mm cabinet plywood. It also had a slight redesign to fit the 98/15360 casing. (Wing #1 was designed around the 98/10240 casing, but due to weight gain, the option to fly a higher thrust motor became important.) Two weeks ago, I located a source of 1/2" Baltic Birch plywood, and have now started wing #3 in an effort to further reduce weight. It is in the process of being cut using the same pattern as wing #2, and I am holding off on the skin decision until after further research. In the meantime, I am going to cut and experiment with the winglets. (The carpet on my living room floor is probably not the best place to do a lot of this, but it turns out to be the only available perfectly flat surface of sufficient size. Probably will get kicked back outside when the snow melts. Especially if carbon fiber becomes an option.)

family picture, wing 2 & 3.jpg


skinning wing 2.jpg


routing wing 2.jpg


final progress on wing 2.jpg


cutout wing 1.png
 
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Rocketeer41

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SMR, Your Jayhawk is very cool.:) Quick questions: When did you build it? How big is it? Why 10'' in diamiter? Because I`m really :confused:.
 

stickershock23

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Looking good! I am real curious about fin flutter for this one.

See how the laminates help out. My "h" tail project is going to have the same problem, I think next time I would build my fins different. more like yours.
 

SMR

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SMR, Your Jayhawk is very cool.:) Quick questions: When did you build it? How big is it? Why 10'' in diameter? Because I'm really confused.
Thanks. I am working on this one now, so what you see is pretty much where I am in the progress of building it. (My avatar photo is a different Jayhawk.) The 10" uses Polecat Aerospace components, which is why it is 10.25" in diameter - it is the biggest body tube, nose cone, tailcone combination readily available that was still within my budget. It is 137" tall from the tailcone, 146" when measured from the aft-most edge of winglet.. While not perfectly true to the scale of the actual JayHawk, it is a reasonable upscale of some kits I have previously built and flown, specifically the Madcow 2.6" JayHawk and Polecat Aerospace 4" and 5.5" JayHawks. The most obvious difference's between those and the prototype are the lack of the wire tunnel and the length of the taper at the tailcone. It is also stretched a little in length to help stability issues.
 
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SMR

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Looking good! I am real curious about fin flutter for this one.

See how the laminates help out. My "h" tail project is going to have the same problem, I think next time I would build my fins different. more like yours.
I have changed my fin specs a bit after reading Tim D's paper on flutter, (although I must admit I don't understand all the math.). I originally thought I could get by with thin G-10 over the plywood frame, but will probably end up with some carbon fiber and glass layers over that. It is a relatively high drag rocket and will stay subsonic. I also am narrowing my motor selection to ones that give it a bigger kick off the pad and then taper off rather than sustained acceleration. It's a steep learning curve and I have a lot of work yet to do.

AeroTech  N2000-W.png


CTI  N2500 Classic.png
 
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SMR

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We have continued our work on the wing and winglets this last week. I have finished cutting 3 copies of the 1/2" baltic birch frame for the winglets (2 and a spare) and have been skinning them in sequence. And I have been working on a technique for foaming the wing interior lightening holes. (This gives a little more glue-able surface for the skin to aid in shear forces to combat bending moment and flutter, as well as reducing the surface flexing from differential pressure at altitude.) I decided to use expanding foam to fully fill each void, using a 7 step process. There are 4 holes in each winglet and 16 in the (one piece) wing.

1. tape off the edges
2. mix and pour 2 part expanding foam
3. cover the hole with a layer of waxed paper and glass. (the waxed paper protects the glass. the glass lets you watch the next step.
4. press down on the glass until the foam has expanded into all the areas. glass can then be removed. leave the wax paper on until
the foam has set up, which makes less mess and easier cleanup.
5. foam will rise up out of the cavity like a cake in the oven.
6. after cured, slice the foam level with the wing using a long flat blade. (a hacksaw blade works well)
7. remove tape and sand the foam flush with the wing frame.

2.  expanding foam poured into void.png


4a.  holding glass forces foam to expand into all areas.png


5.  cavity is completely foam filled.png
 
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SMR

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Haven't posted in a while, but still working with the basic wing and winglet cores. I have been filling each of the lightening holes with two part expanding foam, one at a time. After this step is finished (early next week?), the other side of the wing skin is attached. The motor mount then gets mounted into the wing core, and the wing will get some carbon fiber and fiberglass layers for stiffness. Starting to be identifiable.

6. trimming excess foam.png


7. revision 3 wing, fully foamed.png
 

stickershock23

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Incredible! very well done... I don't think you will have any problem with fin flex.
 

MartinVrstal

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Keep up the good work SMR. I love a good Jayhawk scratch build. Looks like I'll have to go to MWP this year.
 

SMR

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This week I finished all the basic wing work by putting a 22.5° bevel on the leading edges of the wing assembly, and the leading edges and sides of the winglets. (Outlines of the lightening holes were drawn on the wing faces to ensure mechanical fasteners go into the frame of the wing and not the foam.) I have also started to build the jig which will hold the wing when installing the motor tube and centering rings, and fiberglassing them in place.

lightening holes masked off.png


foam filled cavities.png


foam trimmed and sanded flush to winglet frame.png


winglet skinned and beveled.png
 
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SMR

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This week we assembled the motor mount and centering rings into the main (revision 3) wing. Everything fit! The top 4" of the motor mount has a 0.7" wide notch to fit over the connecting bar at the top of the wing. (A 1 3/8" length of G-10 coupler will later be epoxied into that for strength.) The top and middle centering rings are drilled for 1/4" all-threads, and the bottom and middle rings are drilled for access to pour 2 ounce expanding foam into the tailcone area later in the assembly sequence. All three centering rings will have 3/4" hardwood blocks added as attachment points for rail buttons. For operational flexibility, one side will have 1500 series buttons, and the other side will have unistrut buttons. Mark at Stickershock23 (http://stickershock23.com) was kind enough to modify the decal set for me, so that either side can face out on launch day. The decals came yesterday, and they are PERFECT. (Thanks, Mark).

JayHawk wing, motor mount attached.png


detail of notched motor tube.png


Stickershock23 Jayhawk decal set.jpeg
 
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WillMarchant

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The Jayhawk is just a great looking beastie. Thanks for keeping us up to date on your build progress...
 

dpower

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Your project would make for a great Sport Rocketry article. :)
 

SMR

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Your project would make for a great Sport Rocketry article. :)
Thanks. That might be an option after we see how she flies, and if we get any pictures. I don't want to jinx her.

P.S. I was pretty bummed when Extreme Rocketry closed up shop.
 

dixontj93060

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Thanks. That might be an option after we see how she flies, and if we get any pictures. I don't want to jinx her.

P.S. I was pretty bummed when Extreme Rocketry closed up shop.
Actually ROCKETS is still open for business and will be at Thunderstruck.
 

SMR

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We have been dividing our time over the last few days, between attaching the 98mm motor tube to the wing assembly, and gaining some experience and confidence in working with carbon fiber. I chose G-10 for the motor tube as I feel it's stiffness would help offset some of the liabilities of the main wing's sheer size (the tang alone is 34" long). JB Weld is used here as the primary epoxy between the motor tube and the wing. A layer of 5.7 ounce plain weave carbon fiber and a layer of 8.5 ounce fiberglass cloth are to be added to the wing later this month, using West Systems epoxy. (It would probably have been easier to laminate the wing prior to attaching the motor tube, but the fiberglass cloth layer wraps around the motor tube to reinforce the wing joint, so it has to be done after the motor tube is in place.) More on this later.

Centering rings #1 and #3 are attached temporarily at this point, so I must be careful to not inadvertantly get epoxy on them yet. (They come off, one at a time, to be able to reach inside the body tube to add internal fillets and fiberglass tape.) Ring #2 is a double, and fits in a slot previously cut into the main wing. It is a critical stress point in the airframe, as it anchors the wing, motor tube, and recovery harness, so I added eight small angle brackets to augment the fillet between the wing and the ring. I was fortunate to have access to an Omni Manufacturing "Tight Fit Drill Kit". (Thanks, Dad!) The system uses threaded drill bits, eliminating the chuck, and allows drilling around corners and into deep, narrow, and otherwise inaccessible locations.

90° angle drill bit.png


drilling for 90° brackets in centering ring #2.png


adding 98mm G-10 motor tube to wing assembly.png
 
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SMR

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Meanwhile, I added laminates (5.7 ounce carbon fiber and 8.5 ounce fiberglass cloth) to the winglets. I did the winglets first, as they are smaller and more easily replaced for fatal goofs, but the CF layer didn't turn out to be significantly harder than fiberglass alone. I sprayed 3M Super 77 on the edges before cutting, to minimize fraying. (Thanks to Tim D. and Dave B. for pointers here.) I then made a giant press out of 26" squares cut from a ping pong table (flat, strong, available. sorry, kids!). wax paper kept the epoxy from sticking to the press, then 9 easy steps per side... paint the winglet with West Systems epoxy, lay on the CF, pressed it in to fully saturate the cloth, add more epoxy, add the fiberglass cloth, press it in to fully saturate the cloth, add more epoxy, ensure no wrinkles or bubbles, add top of press and clamp down. wait overnight (the hardest part).

I knew the CF would not make the corner of my beveled leading edges, so I cut it a little smaller than the winglet and just cleaned up the existing bevel after the epoxy set. Ready to tackle the wing next.

cutting carbon fiber.png


26" x 26" press table.png


winglet after carbon fiber and fiberglass.png
 
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dixontj93060

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Looks like the CF turned out great! Super project--keep it up!

I did the winglets first, as they are smaller and more easily replaced for fatal goofs, but the CF layer didn't turn out to be significantly harder than fiberglass alone.
 

stickershock23

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Man, you have put some great thought and engineering into this build.

That is going to be one sweet rocket.
 

dragon_rider10

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I can't comprehend the amount of work that goes into these HPR beauties. This thing will be a work of art.
 

SMR

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Still plugging away on the main wing. Sorry there aren't many photos here but having epoxied my basement floor, several pair of pants, and a substantial amount of arm hair, I hesitate to bring my camera into the same room. When everything is dry and it is safe to do so, pictures to follow.
 

SMR

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Meanwhile, in my "clean room", I am laying out the main avionics bay. The Jayhawk will recover with an intact airframe, using a Defy Gravity "Tether" to release the main parachutes. Similar to many dual deploy rockets, the avionics bay is inside the coupler between the motor section and the payload section of the airframe. The coupler does not, however, separate in the apogee event. It functions as a body joint, allowing the rocket to come apart for transport, but is permanently attached to the lower body. The reinforced forward plate of the avionics bay is the attachment point for the recovery harness, and carries the stress through all-threads to the motor mount and main wing. The forward body tube is non-load bearing in the recovery.

I will be flying two sleds, with up to 4 Perfectflite MAWD altimeters. All have flown previously in various paired combinations to verify their operation and accuracy. In addition, a separate avionics bay will be in the nose cone, and will contain a separate MAWD with a transmitter for real-time downlink of altitude information, and a radio locator beacon.

If everything operates correctly...

At apogee, independent altimeters in the avionics bay fire redundant black powder charges in the forward payload bay, overpressurizing the forward payload bay, which pushes the nose off and deploys the drogue parachute. The drogue parachute pulls out a 40’ length of shock cord attached to the top of the main parachute deployment bag, which is held in the forward payload bay by the tether.

The rocket falls under the drogue parachute until approximately 1100’ AGL, at which point the primary altimeter fires a 1/4 gram black powder charge within the Tether’s combustion chamber. (The secondary altimeter fires a different 1/4 gram black powder charge at 900’ AGL as a backup.) This overpressurizes the interior cup of the Tether, forcing the two halves apart, which releases two quick links. The bottom link remains attached to the forward avionics bulkhead, and also retains both halves of the tether combustion chamber cup via a stainless steel cable. The forward link, now free to leave, allows the drogue parachute to pull the main parachute deployment bag out of the forward payload bay. The drogue pulls the deployment bag off of the main parachutes and then separates with the nose cone. The main parachutes inflate and bring the remainder of the rocket gently to earth.

electronic sled wiring.png


universal AV sled, front.png


universal AV sled, back.png
 
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stickershock23

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Meanwhile, in my "clean room", I am laying out the main avionics bay. The Jayhawk will recover with an intact airframe, using a Defy Gravity "Tether" to release the main parachutes. Similar to many dual deploy rockets, the avionics bay is inside the coupler between the motor section and the payload section of the airframe. The coupler does not, however, separate in the apogee event. It functions as a body joint, allowing the rocket to come apart for transport, but is permanently attached to the lower body. The reinforced forward plate of the avionics bay is the attachment point for the recovery harness, and carries the stress through all-threads to the motor mount and main wing. The forward body tube is non-load bearing in the recovery.

I will be flying two sleds, with 4 Perfectflite MAWD altimeters. All four have flown previously in various paired combinations to verify their operation and accuracy. In addition, a separate avionics bay will be in the nose cone, and will contain a GPS tracker and transmitter for real-time downlink of altitude and position information, and a separate radio locator beacon.

If everything operates correctly...

At apogee, independent altimeters in the avionics bay fire redundant black powder charges in the forward payload bay, overpressurizing the forward payload bay, which pushes the nose off and deploys the drogue parachute. The drogue parachute pulls out a 40’ length of shock cord attached to the top of the main parachute deployment bag, which is held in the forward payload bay by the tether.

The rocket falls under the drogue parachute until approximately 1100’ AGL, at which point the primary altimeter fires a 1/4 gram black powder charge within the Tether’s combustion chamber. (The secondary altimeter fire a different 1/4 gram black powder charge at 900’ AGL as a backup.) This overpressurizes the interior cup of the Tether, forcing the two halves apart, which releases two quick links. The bottom link remains attached to the forward avionics bulkhead, and also retains both halves of the tether combustion chamber cup via a stainless steel cable. The forward link, now free to leave, allows the drogue parachute to pull the main parachute deployment bag out of the forward payload bay. The drogue pulls the deployment bag off of the main parachutes and then separates with the nose cone. The main parachutes inflate and bring the remainder of the rocket gently to earth.

That is very interesting. I have been thinking about almost the same approach on my Mercury little Joe. I talked to DefyG he said you can use a cable (hard to describe.. ) the cable straps across your main. and loops through a quick link. when the tether releases the cable it release the "e-bay" (already under drogue) the drogue now is the main for that half of the rocket. BUT that also has a d-bag tied to the bottom of it. and the dbag is on your main.. so the drogue pulls the dbag out. pulling the main out of the airframe. and releasing the main. letting the two half's come down separately. seems like it should work well.
 
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