Wildman 2.6" Jayhawk kit - build thread

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

SMR

Entropy Demonstrator
Joined
May 15, 2009
Messages
2,134
Reaction score
169
Just back from a family vacation / EF tour of China, and picked up 2 weeks of stopped mail. Mostly bills and junk mail, but one pleasant surprise was the arrival of the fiberglass 2.6" Jayhawk kit from Wildman Rocketry. The kit is well designed, beautifully executed, and everything trial fit perfectly.

What you get...
2.6" x 8.5" fiberglass infused polycarbonate nose cone, 3.27 Ogive, slotted for the canards
1-piece fiberglass canard section (contains both canards), slides through nose cone slot
1 fiberglass nose cone bulkhead​
2.6" x 22" fiberglass body tube, slotted for the main wings
2.6" fiberglass infused polycarbonate conical tailcone
38mm x 14" fiberglass motor mount tube
2 fiberglass centering rings (mid and forward)
1 plywood centering ring / thrust ring (aft, must be sanded to fit into the inside taper of the tailcone)
2 main wings, 3/32" G10 fiberglass, CNC cut with tabs for winglet attachment
2 winglets, 3/32" G10 fiberglass, CNC cut with slots to match tabs on the main wings
4500 high temperature 2 part epoxy

what you will need...
rail buttons
recovery harness
parachute
motor retention
paint and decals​

2.6in jayhawk.jpg

Screen Shot 2015-06-22 at 7.37.50 PM.png

Screen Shot 2015-06-22 at 7.38.51 PM.png

Screen Shot 2015-06-22 at 7.40.53 PM.png
 
Last edited:
I'm a notoriously slow builder, and I know some of you will race ahead, so let me start with a quick Rocsim file. Starting position with components and no slop added for epoxy or hardware, it will need 14 ounces of nose weight for a 38-360 motor (I161 White Lightning), slightly less (12.5 ounces) for a 38-240 (H123-W). It should fly nicely on F and G motors also, with a significantly higher probability of getting it back.

View attachment 2.6%22 Jayhawk (Wildman).rkt

Screen Shot 2015-06-22 at 4.59.01 PM.jpg

Screen Shot 2015-06-22 at 5.07.28 PM.jpg

Screen Shot 2015-06-22 at 5.07.44 PM.jpg

Screen Shot 2015-06-22 at 5.09.00 PM.jpg
 
Last edited:
Subscribed! I'm looking forward to seeing how it goes together. I've been thinking about getting one of these for my son's birthday.
 
I am look forward to the build thread Sather! :pop:

Zach
 
Last edited:
First step, as in all fiberglass rockets, is to wash off the components. I use a tub (re-purposed cat litter box) full of hot sudsy water (Dawn dishwashing detergent), followed by a thorough rinse of hot plain water and a gentle towel dry. This will get all the mold release agent off the glass components. Step 2 is to rough up all the surfaces that get epoxied with a good bit of coarse sandpaper. And while you are at it, use your best technique (sanding, router, etc.) to give a nice taper to (or just break the square profile) of the leading edges of the main wings and the winglets. Also both the leading and trailing edges of the canards. No need to do the trailing edges of the main wings or the winglets, save your energy and attention to detail to do a really good job on the leading edges. Take care not to disturb the tabs on the tip chord (outside edge) of the main wing - it is important in winglet alignment. And cut out the molding sprue (tree) from the inside of the tailcone. Wash everything again.

WARNING - I know a lot of us have had good luck using acetone as a washing agent for fiberglass components. DO NOT USE Acetone with the nose cone or tailcone, as they are glass-infused polycarbonate. Base on my limited knowledge of chemistry and a rudimentary internet search, I believe acetone will melt the plastic.

note - pictures to follow. As soon as I find the cable to upload them from my camera, which I managed to misplace while unpacking from my China trip.

Screen Shot 2015-06-22 at 1.28.38 PM.png
 
Last edited:
Subscribed! :pop:

I was actually thinking about starting my build on this one today - I had searched in the past week for build tips and even emailed Tim to see if there were any instructions...he replied "Nothing yet on the Jayhawk ...use the Black glue to hold the winglets on. The mix ratio is 5.5-1". So thanks for starting this one! :)
 
I have started mine. Used a slimline motor retainer. I put a 1/2 inch wide single wrap of fiberglass on the retainer end of the motor tube. It would have been an extremely loose fit and I wasn't sure JB weld alone would have worked. I would have also had to use a motor case to center the retainer. I have the motor mount installed along with the tail cone and one fin.
 
Okay, back to work. I still have not found my camera's cable, but as luck would have it, my wife's Garmin cable has the same exact plugs. Hoping that none of them were cross-wired or re-purposed in that proprietary application, I plugged them in and voila... pictures appeared on my computer.

So, the first is the unboxing. This is what comes with the kit.

Second photo is the tailcone with sprue attached. This should be cut off carefully with an X-Acto knife or sharp, small wire cutters. Don't put too much pressure on the side of the tailcone as you do so. If you have a nub or two left over, no worries. Sand them off with coarse sandpaper, as roughing up the inside of the tailcone helps epoxy and won't affect your (optional) paint job at the end of the build.

Third picture - Sprue removed from the tailcone, and the inside of the tailcone and outside of motor tube sanded to improve epoxy adhesion. The aft (plywood) centering ring is shown as it comes in the box. It is the same O.D. as the O.D. of the aft end of the tailcone, so it must be sanded down (with a taper) to properly fit inside the tailcone. This may seem like a difficult process, but turned out to be relatively simple, with a couple of fall-back options should you inadvertently take too much wood off. The 38mm Aero Pack body is being recycled from my now-retired L1 rocket, coincidentally also a Jayhawk.

Fourth picture - aft ring marked for sanding. I lined up the O.D. of the ring and the tailcone, and then marked the ring around the inside of the tailcone with a sharp pencil.

Fifth picture - I used the tailcone to set the proper angle on my bench sander, and using the motor tube as a mandrel, turned the aft ring against the spinning sandpaper disk, incrementally, until it fit perfectly up inside the tailcone. (The ring is now a transition, matching the I.D. of the tailcone.) In the event you take off a little too much, the ring will go too far into the cone, sticking out the back end. You can then sand the face (aft surface) of the ring to bring it back flush with the tailcone.

IMG_6654.jpg

IMG_6656.jpg

IMG_6661.jpg

IMG_6666.jpg

IMG_6667.jpg
 
Last edited:
How did I know it'd be you to put up a thread on one of these? :wink:

Braden

Yeah, no pressure here. I had better do a good job... my reputation in the Jayhawk Secret Society is riding on it.
 
Last edited:
In the event you take off a little too much, the ring will go too far into the cone, sticking out the back end. You can then sand the face (aft surface) of the ring to bring it back flush with the tailcone.

My sanding effort did result in the ring sticking out about 1/16" too far, so I marked the edge and sanded the face of the ring to match, resulting in a nice flush fit.

I intend to assemble the ring to the tailcone with the included 4500 high temp epoxy which was thoughtfully included in the kit. Both JLRockets and I used it in our respective recycling container projects, and it appeared to do a pretty good job (compared to other epoxies) in bonding to plastic.

IMG_6674.jpg

IMG_6676.jpg

IMG_6705.jpg
 
I'm a notoriously slow builder, and I know some of you will race ahead...

One of the reasons for my leisurely pace is that I divide my builds into what I call "glue events". Since I normally use slow epoxy and let things dry overnight, I can basically do one set of events per day. I know there a many ways to do something, many are equally good, but this is just what works for me.

Last night, I assembled the aft end of the motor mount tube, to include the AeroPack and the wood (tapered) ring. Trial fit everything to ensure they fit BEFORE mixing epoxy. Then I slid the wood ring onto the motor tube, far enough up to be out of the way when applying a skim coat of JB Weld on the outside edge of the tube for the Aero Pack body. Then, I put the same tiny amount on the inside of the Aero Pack itself, spreading it evenly with a popsicle stick. (JB Weld is good for this step as it is the consistency of toothpaste, so easy to work with, and has excellent high temperature characteristics when cured.) Pushing the Aero Pack onto the tube, a little JB Weld oozes out of the seam, both on the inside of the Aero Pack and the outside of the tube. Carefully wipe the inside of the tube with a paper towel, repeatedly, until it comes out clean. This is important, as it affects how your motor casings will slide into the motor tube. (Note - any residue that you miss can later be scraped off of the aluminum with an X-Acto knife, or sanded from the inside of the fiberglass tube. It is just easier to do it now while the epoxy is wet.)

There will still be a little bit of JB Weld on the outside of the motor tube. Holding the Aero Pack in position against the tube, slide the wood ring aft until it rests against the Aero Pack. The epoxy will squish out, and you can make a nice little fillet on the aft side of the ring, keeping it small so as not to affect putting the Aero Pack cap on at a later point in time. (photo 1) Or, you can wipe it off completely if that suits you, this one is cosmetic.

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.

Wipe any epoxy off of the outside, tapered edge of the ring (or sand it off later) to keep a good fit inside the tailcone. Set the assembly aside, Aero Pack end down, to dry. Overnight.

IMG_6723.jpg

IMG_6730.jpg
 
Last edited:
The aft (plywood) centering ring must be sanded down (with a taper) to properly fit inside the tailcone. This may seem like a difficult process, but turned out to be relatively simple, with a couple of fall-back options should you inadvertently take too much wood off.

Or, if you are truly intent on loosing this rocket, with a little sanding, a 54mm motor mount will fit nicely in the tailcone with no need for an aft ring. Just replace (or bore out) the front 2 rings and you are good to go.

IMG_6715.jpg

IMG_6716.jpg
 
Prepping for this afternoon's build session. The next few steps can admittedly be accomplished in a different order, with a caveat to be careful not to paint oneself into a corner. (i.e., now that the aft ring is on, make sure you get the middle ring on before permanently installing the forward ring. Ask me how I know this.) I prefer to work from the aft end forward, so I'll start with the tail cone installation, using the body tube to line it up properly. Therefore, the mid and forward rings are installed temporarily with masking tape (photo 1), to align the motor tube in the body tube (photo 2). Be careful to only get epoxy on the tapered outside surface of the aft (wood) ring. (The Aero Pack is masked off here to protect it.) As always, trial fit everything before mixing epoxy (photo 3).

Steps to permanently install the tailcone onto the motor mount...
(a) remove the tailcone (from photo 3) and pull out the motor tube slightly (as in photo 2)
(b) mix a small amount of the 4500 high temp epoxy with a 5.5 : 1 ratio.
(c) holding the tubes horizontally, skim coat the outside edge surface of the aft (wood) ring. (Caution - DO NOT tip the assembly vertical (Aero Pack end up), to prevent dripping epoxy onto the mid centering ring. The motor mount assembly will be removed in a subsequent step, so do NOT get epoxy on the rings, inside the body tube, or on the shoulder of the tailcone.)
(d) carefully position the tailcone over the Aero Pack, and slide it forward into position, with the sleeve of the tailcone fitting up into the aft end of the body tube. Pulling on the Aero Pack while pushing the tailcone will make this easy. As it fits into position, the inside of the tailcone and the outside of the wood ring will squish out a little epoxy as they touch. Wipe off the excess on the exterior, live with the excess on the interior. (photo 4)
(e) set the assembly aside (Aero Pack end down) to dry. Overnight. Note the orientation of how pieces may migrate while the epoxy is setting... i.e. depending on how loose / tight your tailcone shoulder is, you may need to put some tape around the body tube-tailcone joint to keep the tailcone from slowly slipping down while the epoxy is wet. Also, if you set it on the Aero Pack, the weight of the body tube and tailcone may cause it to slide off of the tapered edge of the aft ring. I clamped my body tube to a drawer, so the weight of the motor mount pressed down against the tapered aft ring, keeping everything tight during the cure. (photo 5)

Note - the 4500 high temp epoxy is like tar... it smells and you'll get it on everything. Work with it in a place that can accept some permanent damage, i.e. not your kitchen.

IMG_6735.jpg

IMG_6738.jpg

IMG_6746.jpg

IMG_6753.jpg

IMG_6757.jpg
 
Last edited:
One of the reasons for my leisurely pace is that I divide my builds into what I call "glue events". Since I normally use slow epoxy and let things dry overnight, I can basically do one set of events per day. I know there a many ways to do something, many are equally good, but this is just what works for me.

I fall into this exact category and practice as well.
 
After a full night of epoxy curing, I carefully pulled the motor mount out of the body tube. The motor mount now includes the aft ring, motor retention, and the tailcone (photo 1). The assembly in this configuration (tailcone attached only at the aft end) appears somewhat fragile, so I beefed mine up a little. Keep in mind that when installed in the body tube, the forward shoulder of the tailcone adds considerable strength. So, steps (a) thru (c) below are completely optional. One can just jump to step (d) and install the mid ring, but be careful not to bump or drop the motor mount assembly before installation in the body tube.

(a) Using a little of your favorite epoxy, add a fillet on the forward side of the tailcone / aft ring joint. This involves reaching inside the tailcone with minimal clearance, so be careful not to stress that existing bonds. Mask off the tailcone shoulder and the motor tube to protect the mating surfaces. I used West epoxy with a little chopped carbon fiber, and a thin dowel to push the epoxy down into the gap and then spread it fully around the perimeter. The clear tailcone makes it easy to see your progress. (photo 2)

(b) Use a good quality, light-weight 2-part expanding foam to fill the tailcone interior (photo 3). Two pound (per cubic foot) foam is more than adequate, and the weight in such a tiny volume is insignificant. Do not use Great Stuff or other canned foam, it cures by exposure to air, and in an interior space, it won't get any and may never cure. 2-part foam cures chemically, like epoxy, so it works great in enclosed spaces like tailcones and nose cones.

(c) After it dries, carefully remove the excess foam. You can cut it down with an X-Acto knife and/or razor saw. Be careful not to cut into the fiberglass or plastic. If you cut slowly, you can feel the saw touch the masking tape (the pull is different), and stop there. Once you are down to the masking tape, pull off the tape and you have a clean surface remaining (photo 4).

(d) Put a bead of JB Weld around the motor tube, slightly forward of the edge of the tailcone shoulder. Slide the middle centering ring down the motor tube until it rests on the tailcone shoulder. This forma a fillet on the aft side of the mid ring. Set the assembly aside, Aero Pack end up, to cure. When dry, flip the assembly over and put a bead of JB Weld around the forward side of the mid ring. Set the assembly aside, Aero Pack end down, to cure.

IMG_6766.jpg

IMG_6793.jpg

IMG_6797.jpg

IMG_6820.jpg

IMG_6826.jpg
 
Last edited:
Back from another trip... back to work on the Jayhawk. Today I will be attaching the top ring and the recovery harness. As always, there are as many techniques to do this as there are rocketeers - this one works for me. A couple of caveats...

(a) Since I can't fit my hands into the 2.6" body tube, no need for a U-bolt... I'll just permanently attach a length of kevlar to the motor mount.

(b) the fin tang has to fit between the top and middle rings. The root chord of the wing ALSO has to follow the bend as the body tube joins the tailcone. So, important to trial fit everything before committing to final epoxy fillets. You may have to trim the tang a little on one end to accommodate.

picture 1 - filed a notch in two sides of the top ring to clear Kevlar shock cord, which will be epoxied to the side of the motor tube between the top and mid rings.

picture 2 - cut approx 36" of Kevlar, trial fit the assembly, and then tacked (medium cyanoacrylate) the top ring (aft side) to the motor tube.

picture 3 - after cyanoacrylate set, put a fillet of JB Weld around the forward edge of the top ring. note - I used JB Weld here both for its high temp properties, and because it is thick, so that the Kevlar won't "wick it up" as it would a liquid epoxy (which would create a weak spot).

IMG_6829.jpg

IMG_6852.jpg

IMG_6863.jpg
 
Last edited:
The steps I used to complete the motor mount...

(a) cut an appropriate length of shock cord
(b) notch the top ring to fit shock cord on opposite sides (to deconflict with wing tang area)
(c) trial fit everything in position
(d) tape shock cord in position and tack the top ring in place with cyanoacrylate (super glue). use care to not get CA on the shock cord
(e) apply a fillet of thick epoxy around the forward side of the forward ring. Use caution to keep epoxy from "wicking" up the shock cord
(f) epoxy shock cord down sides of motor mount, individually...
(1) lift shock cord out of the way
(2) apply epoxy down the side of the motor tube
(3) pull the shock cord taut and press into the epoxy
(4) using a toothpick or popsicle stick, press the shock cord fully into the epoxy
(5) spread the excess epoxy over the top of the shock cord
(6) set aside to dry
NOTE - the strength of the shock cord retention is the shearing resistance of this epoxy bond. Ensure the shock cord is fully imbedded into the epoxy.​
(7) repeat for other side​
(g) apply epoxy fillet on aft side of top ring.​

The motor mount is now complete and ready to be installed into the body tube. (When I get back... off to London for the 4th of July. They celebrate that there, don't they?)

IMG_6874.jpg
 
Last edited:
Sather, remind me to invest in JB Weld :jaw:

Yeah, I figured I'd take some flak for that. It is more expensive, but it doesn't run (or wick up) at all. My other frequently-used options include West Systems, but in the really small quantities needed during this build, mixing JB Weld was easier than wasting a full pump's worth of West every time I put a piece on.
 
Now that the motor mount is complete, time to install it in the body tube. It is important to keep the shock cord areas of the motor tube away from the wing slot areas of the body tube, so that the wing tang has a smooth surface to contact. I marked the tail cone with a Sharpie to ensure the shock cords ends wind up 90° from the wing slots. Trial fit to make sure everything fits properly. Tuck the shock cord into the motor tube to keep it out of the way, then spread some runny epoxy around the forward surface and edges of both exposed rings (the forward and the mid), as well as the edge of the tailcone coupler sleeve. Finally, quickly slide the motor tube into the body tube, referencing your alignment marks to keep the tang areas clear. Wipe off any excess epoxy that squishes out the seam between the body and the tailcone. Spin the body tube a few times, in the air (oriented vertically), catching it between spins, so that the centrifugal force will help the epoxy on the forward edges of the rings flow towards the inside of the body tube, making fillets. Set aside, tailcone down, to dry.

IMG_6879.jpg
 
Last edited:
Now that the motor mount is permanently installed in the body tube, again trial fit the main wings. My mid ring sits flush against the tail cone, yet sticks up about 1/16" beyond the aft edge of the fin slots. I had to take off the corresponding 1/16" from the aft edge of the tang so it will fit into the slot and still line up the angled root chord of the wing against the bend at the body tube / tailcone. Also, since I put rounded fillets on the tang sides of both centering rings, I rounded the square corners of the tangs to fit against the fillets. It is easier to work with the wings at this point if you have not yet installed the winglets.

IMG_6890.jpg
 
Last edited:
Once everything fits to your satisfaction, it is time to attach the winglets. The tabs (2) on each CNC-cut main wing have perfectly square corners, while the slots (2) in each winglet have rounded ends. The temptation therefore would be to round off the tabs or square off the slots. Don't do it - they are designed for a nice tight fit. Just (a) place the winglet flat on a firm surface (garage or basement floor works fine), (b) hold a wing over it and line up the tabs with the slots, and (c) give the wing a few gentle taps with a hammer to seat it firmly into the winglet. The advantage of the tight fit is that it also holds the winglet perfectly perpendicular to the wing. Any sanding you would do might make it a loose fit and correspondingly less likely to hold itself to a proper 90°.

Once the winglets are on the wings, you may mix a little of the included epoxy and create fillets along the joint on the inside edges. I am choosing to delay this step until the wings are attached to the body. There is an economy of effort when it is possible to do two fillets simultaneously (wing to body and opposite wing to winglet). Roll the body in 90° increments and you are done in 4 steps instead of 8.

First photo is winglets firmly fit to wings, no epoxy yet, and trial fit into the body. We are almost done, just a few glue events and paint... she will be ready to fly by Eat Cheese or Fly, the annual WOOSH regional launch, this year on 25-26 July. Not to hijack my own thread, but the trophies for some of the events at ECOF are now ready (photos 2 & 3).

IMG_6898.jpg

IMG_6131.jpg

IMG_6145.jpg
 
Last edited:
I glued one wing on tonight. Mixed some thick epoxy, spread along the edge of the tang with a popsicle stick, and inserted into the slot with the rocket flat and the slot pointed straight up. In a two-finned rocket, even more so than 3 or four finned ones, the straightness of the fins/wings is critically important. Take time to make sure it is lined up correctly and set aside to dry. Overnight.

photo - Luckily, the 2.6" body will fit perfectly in the normal-size fin alignment jig. Needed to counterweight it, though, as it doesn't balance well sticking almost all the way out due to the long wing.

IMG_6902.jpg
 
Last edited:
While the wing attachment is curing, you can get the canard (nose wing) attached. It is a one-piece item in the kit, including both canards and a common tang, CNC-cut perfectly to fit through the slot in the nose cone. The width of the tang corresponds exactly with the width of the nose cone, wider towards the aft. However, when you bevel the leading and trailing edges of the canards themselves, you will lose the nice, easily defined corners that identify where the canards end and the tang begins. So, before you glue anything, trial fit and mark where the canards line up with the nose cone, and measure to ensure it is even (equal exposure left and right). Tack in place with thick CA. I will do the external fillets during wing fillet time, so as to get 12 fillets done with 4 body rotations.

IMG_6883.jpg

IMG_6905.jpg
 
Last edited:
Wing 2 went on last night. One measure of how accurately the wings, winglets, and slots were cut is if she stands upright without rocking like a table with one short leg. This one is perfect.

Just a few steps remaining... nose cone weight & bulkhead, rail buttons, fillets, and paint. On track for ECOF.

IMG_6911.jpg

IMG_6922.jpg
 
Looking great! You seem to be progressing very well considering that you call yourself a "notoriously slow builder". ;)

Also I didn't even think of all the fillets needed until you mentioned it...oh boy. :bangpan:

Thanks. This one has gone together quite easily, as the pieces fit well right out of the box with very little fiddling. I allowed myself a month, mostly because my job takes me out of town a lot, but it could easily be built in a week. (Other than the fillets!) Sather
 
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.
 
Back
Top