Wildman 2.6" Jayhawk kit - build thread

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I ordered one of these for my son's birthday today. He really likes the Saab I just finished so I hope he likes it.

I'm sure he will. The Jayhawk is a unique rocket, always a crowd pleaser, and this one will go together easily AND be durable.

Today I finished the rail button installation. It is easier to mark the centerline before wing installation, but should definitely be done prior to fillets, as the sharp edge of the slot is a better defined reference point than the radius of a fillet. Measure the circumference of the rocket between two wing slots, divide in half, and mark this as the centerline of the rocket for button installation. I placed my lower button above the seam of the body tube / tailcone (this is into the shoulder of the tailcone and aft of the mid ring, so as to be as far back on the body as possible). The upper button is just aft of the top ring (so as to not interfere with the recovery harness). This worked out to be 1/2" and 10 1/4" from the aft edge of the body tube.

Choose your drill bit carefully... it should be the same size as the shank of your screw, but smaller than the teeth, so the shaft won't bind going into the hole while the teeth will cut threads into the fiberglass. I left my screws long on purpose, so when I was cutting the threads I could sight down the fuselage and ensure they were lined up with each other. This eliminates the possibility of having cock-eyed buttons. Once you are happy with the threads and alignment, cut them to length (or replace them with shorter ones). A 38mm motor tube in a 2.6" body leaves only about 1/2" of room on each side. Accounting for the 1/4" thickness of the button, I cut my screws to 3/4" total length and they went in fully without bottoming out against the motor tube.

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How much nose weight did you decide to use?
Ted

I'm not quite there yet, but getting close. My ballpark estimate is in one of the first posts of this thread, but my final will be determined by how much weight the fillets and epoxy actually added to the build, which weren't accounted for in the original rocsim. My off-hand guess will be about 14 ounces. A Jayhawk with a correctly scaled body (unlike most of my Oddroc fleet) should have the Cg at least at the 60% point (measured from the tip of the nose to the aft edge of the tailcone).
 
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Fillets in progress. I used the included epoxy only to bond the aft ring inside the plastic tailcone, so there was an ample supply remaining to do all the fillets. 3 at a time (canard to nose cone, wing to body, opposite winglet to wing), so 4 sessions and we'll be ready for paint.

P.S. A word about the fiberglass infused polycarbonate nose cone. My good friend Ben W. recently sent one well in excess of Mach 2. The rocket was unpainted and the nose cone was painted red. Post flight, the melted paint had flowed down the body tube, while the newly bared nosecone looked brand new (photo 2). These nose cones can hold their own against a lot of heat!

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3 more fillets completed, 3 remaining of 12 total. During the lull, I also filled the rectangular indentations where the wing tabs fit thru the winglet slots. I used Super Fil, but Squadron Putty would work just as well. One more fillet session tonight, and tomorrow we paint.

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Nose cone after wet sanding and primer. Couple of low/high spots on fillets yet to sand, then ready for final paint. I did the nose cone first as it gets two colors... orange (to include the canards) and black (forward of that).

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Sather all I can say is :

Tim picked the right guy for this project!

How many of these things [including all mod versions] do you have now?
 
Sather all I can say is :

Tim picked the right guy for this project!

How many of these things [including all mod versions] do you have now?

Thank you, Jim. That's a good question, I had to go count them. The answer is, including this one, 22. Most are small, a couple are group efforts.

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You put the Magnum in Magnum Jayhawk..

CaveDuck will go gaga when he sees the Gooney AQM-37 !

Kenny
 
Well Jacob thought it was pretty cool. We'll have to get started on it soon. I'd like to find a decal set for it. Madcow has a 2.6" Jayhawk that includes water slide decals. Maybe they'll sell the separately.
 
Well Jacob thought it was pretty cool. We'll have to get started on it soon. I'd like to find a decal set for it. Madcow has a 2.6" Jayhawk that includes water slide decals. Maybe they'll sell the separately.

Or wait for Mark to reopen Stickershock

https://stickershock23.com/JAYHAWK.html

I bought a set when he opened up a couple weeks ago :cool:
 
Alternating primer colors helps identify high and low spots during sanding. My goal was to make the transition from body to tailcone seamless. Final primer is white as it helps the low-hiding orange stay bright. Nose cone tip is done in satin black. Conventional wisdom would have one paint the darker color (black) after the lighter color (orange), but the geometry of masking the taper is easier in this direction.

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CaveDuck will go gaga when he sees the Gooney AQM-37 !

"You can make anything fly with the proper use of nose weight." Isaac Newton, 1687 (paraphrased)

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Final paint today. A few specks of dust which I'll have to live with, and some tape residue on the Aero Pack and the radome (black portion of the nose cone), which I will clean up after the paint dries. Nose weight and bulkhead tonight. I did final paint before nose weight only because I believe epoxy cures faster than paint dries, so I'm giving the paint a little extra time as I am running in to time constraints for Saturday's launch. She will fly naked in support of Marion Hayes.

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why do you need such thick fillets on this build??


Thick as in big or thick as in not runny? If you thought they were big... They are actually very small in radius, although in the pre-sanding pictures (black on black) they look larger because I don't mask the edges. I wet sand them to blend in. I made them small to stretch the included epoxy (intended for the winglets) to all body fillets. (I pull the fillet with my thumb, so how hard I press defines the size of the fillet, so tape doesn't work for me.)

If you meant viscosity, it was just personal preference. Any epoxy will do. The nose cone / canard fillets used a thicker epoxy because the gap between them which was created by beveling the leading and trailing edges left little holes to be filled, which could also have been done after the fact with spot putty. I also used thick epoxy for the kevlar as it was left over from a simultaneous project, so saved some time.

The internals are a different story, as mentioned in the posts assembling the Aero Pack and aft ring. Since the thrust ring does not contact the tang, pretty much all the load path initially goes up the motor tube. I prefer not to rely solely on the strength of an epoxy joint, but where mechanical / physical contact is lacking, it sometimes becomes necessary.

Using the remaining epoxy, make a good fillet on the forward side of the wood ring. (photo 2) This one is important. The aft ring (thrust ring) transfers the thrust of the motor to the rest of the rocket. In a typical high power rocket, this occurs in several load paths, including through the ring to the body tube via the epoxy joints on the rings between the motor tube and the body tube, as well as through the aft ring to the TTW fin tangs and then to the remainder of the structure via physical contact. With a tailcone, the aft ring does not make direct contact with the fin tangs, so the epoxy on the ring carries all the load. On some of my bigger projects with tailcones, I have included ribs here to provide another load path, but the weight (and thrust requirements) of this Jayhawk does not warrant the additional weight aft of the Cp.

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Nose weight and bulkhead/recovery attachment. I'll start with the acknowledgement that the following steps are way overkill*... it is probably just as effective to loop some Kevlar around the canard tang, inside the nose cone, and be done with it. But, since the kit comes with a nose cone bulkhead, and weight needs to be added up there anyway, let's add some hardware (photo 1) and make the weight functional. I drilled the bulkhead for a stainless U-bolt (1" wide) and two all-threads, (1.25" apart). The all-threads were cut and bent to fit up into the tip of the nose, where the lead will be. They were also staggered slightly to fit around the canard (photo 2). I added 7.6 ounces of lead ballast, mixed into a slurry with West Epoxy (slow version), and poured into the nose cone. Use a dowel to make sure all the shot gets up into the tip - nothing worse than a loose BB rattling around inside a sealed nosecone. (One can drill a small hole in the bulkhead and injection foam the cavity at a later date if warranted, particularly if a BB does break free.) While the slurry is still liquid, press the bulkhead in place, imbedding the all-threads into the nose weight. Add a fillet of epoxy to the aft side of the bulkhead and set aside to cure, tip down, in your handy Jayhawk nosecone jig (photo 3).

The painted nose cone with canard but not bulkhead weighed 5.4 ounces. When completed with bulkhead, all-threads, U-bolt, epoxy, and lead shot, it weighs 1 pound, 4.2 ounces. So the total weight added was 14.8 ounces, pretty close to my initial estimate. I'll get a good measure of the Cg tomorrow when prepped at the launch. (Can't do it now as the epoxy not yet dry.)

* Having once dropped a weighted nosecone into the parking lot due to a recovery harness failure, nearly beaning a few friends, it is now pretty high up on my list of things to not do again.

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And finally, the inevitable comparison. Pictured are the Wildman 2.6"/38mm Jayhawk (left) and Madcow 2.6"/29mm Jayhawk (right). The Wildman version is slightly longer with a wider wingspan. The Madcow version is cardboard tube, plastic nose cone, balsa tailcone, and ⅛" plywood wings. It weighs in at 1 pound, 4.4 ounces empty (no motor or recovery). The Wildman version is all fiberglass or fiberglass infused polycarbonate. In a similar configuration, it comes in at 3 pounds, 2.6 ounces. The Madcow lists for $79.95 with waterslide decals and a 30" parachute, and was on sale on Black Friday for $64.00 (in VERY limited quantities). The Wildman Jayhawk lists for $109.99 ($98.99 for club members), with a lower introductory price which has since expired.

Editorial... My Madcow Jayhawk was an early model which came with a balsa nose cone. Both the nose cone and tailcone were open-grained which, combined with my limited modeling skills, were difficult to fill and finish properly. The canards were therefore individual and are surface mounted. It flies nicely on an F40-7 White Lightning SU motor, but has needed winglet repairs on exactly 50% of her flights. (There is a single 2" tall tab on the wing and a corresponding 2" slot in the winglet. IMHO this significantly weakens the thin plywood, especially knowing the winglet invariably will be the first point of contact with the ground. Other than issues with the balsa and strength of the winglet, it is a good entry level Jayhawk, particularly with the included decals and parachute.

My Wildman Jayhawk is also an early model. There were zero fit and finish issues, everything fit together perfectly right out of the box. The filament wound fiberglass and glass-infused polycarbonate components provide literally a glass-smooth surface for a nice paint job. The canard is one-piece with a TTW tang, so alignment and installation in the pre-slotted nose cone was easy and durability is assured. There are two tabs on the wings, with corresponding slots in the winglet. These are smaller than the Madcow slots, but spaced further apart too keep alignment easy. Mine has yet to fly, but I feel that the higher strength of fiberglass combined with the smaller slots in the material will better protect the winglets on landing. To the best of my knowledge, this is the first and only fiberglass Jayhawk kit available, flawless in implementation, and an excellent value, particularly in fit, finish, and durability issues.

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You seem to have used a basic bright orange for the main color. Have you ever found a specification for the official color?

No, sorry, I don't. None of mine are perfectly accurate scale models, (lack of wire tunnel on the back side, the length of taper in tailcone, etc. The black radome should actually extend down mid-canard, which is difficult.) If I made one look too good, I wouldn't want to fly it. But since I do fly them, they get scratched and need touch-ups on occasion. So I just use rattle cans, in this case Valspar from Lowes. The two rockets in the previous post are actually the same paint color, but variations in lots and humidity/temperature when applied make subtle variations. Original Jayhawks appear to have a little more red in them, so I have a few painted in Chevrolet Orange engine paint. The finest example of a correct Jayhawk that I have seen is Marty Vrstal's 4" version, which was featured on the cover of the Sept/Oct 2009 Sport Rocketry.

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Thick as in big or thick as in not runny? If you thought they were big... They are actually very small in radius, although in the pre-sanding pictures (black on black) they look larger because I don't mask the edges. I wet sand them to blend in. I made them small to stretch the included epoxy (intended for the winglets) to all body fillets. (I pull the fillet with my thumb, so how hard I press defines the size of the fillet, so tape doesn't work for me.)

If you meant viscosity, it was just personal preference. Any epoxy will do. The nose cone / canard fillets used a thicker epoxy because the gap between them which was created by beveling the leading and trailing edges left little holes to be filled, which could also have been done after the fact with spot putty. I also used thick epoxy for the kevlar as it was left over from a simultaneous project, so saved some time.

The internals are a different story, as mentioned in the posts assembling the Aero Pack and aft ring. Since the thrust ring does not contact the tang, pretty much all the load path initially goes up the motor tube. I prefer not to rely solely on the strength of an epoxy joint, but where mechanical / physical contact is lacking, it sometimes becomes necessary.

Yeah in the black on black they look "wide" ok thanks for explaining
 
Yeah in the black on black they look "wide" ok thanks for explaining

Yeah, sorry for the crappy photos... black on black in the basement (flash) was a tough shot. The fillets show up much better painted on a sunny day.
 

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The 2.6" Jayhawk flew twice over the Eat Cheese or Fly weekend launch. First flight was on a CTI I175 White (38-3G), second on a CTI G185 Vmax (38-1G). Both flights used a 48" Spherachute and a rather long Kevlar shock cord, which did fit in the 2.6" body tube. The second flight was a direct hit on the runway (tightly packed gravel surface originally intended to be the foundation of a runway for a planned but cancelled Air Force Base). Despite the good smack (winglet first, hard enough to bounce), the winglets stayed firmly attached and undamaged. Next up, the premier launch of the central CONUS... Midwest Power.

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Yup. IMHO the inherent flexibility of fiberglass kept the winglets from cracking. It may also have added to the height of the bounce, as it functioned like a spring. I've broken quite a few plywood fins at Bong.
 
Hi SMR,

I thought I'd add to your thread rather than starting a new one so we could keep all of the info in the same thread.

I downloaded your RockSim file and opened it in OpenRocket. OR can't handle fins that are not attached directly to the body tube, so I moved the vertical fins to the body tube. This will keep the weight and side surface area in the correct positions, but it looks weird.

I wanted the cap of the AeroPack retainer abutted to the centering ring without any gaps. IMHO it makes the back end of the rocket look a lot cleaner. So I got a chance to explain to Jacob all the steps needed to cut a new rear centering ring on my CNC mill. We made it so that it slips over the shoulder of the AeroPack retainer and its tapered to match the ID of the tail cone. Since then I've tried my hardest to let Jacob do all of the work and just explain what he needs to do.

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We drilled two 1/4" holes and pressed in PEM nuts for the rail guides, epoxied the motor mount in place, and epoxied the wings in place. We used a pair of 123 blocks on a piece of melamine to keep the wings level.


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We got all of the fillets done yesterday. I also added 22 oz. of weight to the nose. That should balance it for G and H motors. Anything larger will need supplementary weight.

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Looking good!!!

Wow! 22 oz of nose weight! That seemed like a lot of weight and my first thought was it was more then needed. But looking at the canards and long fins, I figure you have it right.

I don't know where the CP is, but I've found that some rockets will handle a variety of motors with little or no adjustment for larger motors because the larger motors put more weight forward and don't affect the CP/CG balance that much. This rocket looks to have a CP pretty far forward, so all bets are off.

Good luck and let us know how it works.
 
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