Convert any Wildman Jr kit to a 2 stage build [Vindicator JR]

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blackjack2564

Crazy Jim's Gone Banana's
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Convert ANY Wildman JR size kit to a 2 stager flier..............

One of my favorite Wildman Jr kits is the split-fin Vindicator Jr.
A 54mm airframe with a 38mm motor mount. Can be flown in motor deploy with or with out the payload for L-1 on G-motors & up. With the payload and dual deploy for a nice J-motor L-2 flight.

Been flying the 3 in Wildman 2-stage quite a bit lately, which is tons of fun, but can get a little pricey when it comes to 2 motors in the J-K-L range.

So thinking it would be nice to do a 2 stage upgrade to one of the JR kits. This can be flown with 29's & 38's in many different combinations keeping it on fields with lower waivers & not taking a bite out your wallet.LOL

How does this work you ask...well ... you take the kit you already have, and use your fincan for the bottom stage/booster. Then build a new fincan for the upper stage/sustainer, which has the fins moves forward so you can couple the 2 stages together with an interstage couple.

This interstage coupler holds the avionics for the booster, acts as the nose cone for the bottom stage/booster and also couples both stages together. You can use motor eject for chute deployment in the booster or altimeter. Then the upper stage flies with dual de-ploy as any other rocket. So.........

What you get:

Complete new fincan for the upper stage, with fins moved forward to allow insertion of the interstage coupler.
Fins, centering rings, motor tube, shock cord, airframe.

Interstage coupler: 54 coupler, vent band, 38mm av-bay tube, centering rings, bulkplates and end caps for av-bay.
DSCN2071_2.jpg


This is how all the parts will fit together when built:

from left... end cap for 38 av- bay and sled...which fits inside the 54mm coupler by way of CR's and interior bulkplate.

This assembly will fit inside the new fincan and butt up against the rear CR which is moved up forward 1 caliper. All held in proper position by the interstage vent band.
DSCN2073.jpg

Hoping to have this finished for a test flight at URRF launch next weekend in New York.

Will be using the MissleWorks RRC3 for staging duties. It's been working perfectly for the 2-stage flights of the Wildman 3.

I'll also be using the new Rocketpoxy for everything on this build.

Tim can tell you what this upgrade is going to cost & will probably have a nice special for every body with Jr size kits that want to join in the fun of flying 2 stage.

He will be making the 2-stage upgrade for all of them.... Wildman Jr., ShapeShifter Jr, DarkStar Jr., Vindicator JR. WildThang Jr and any others I may have forgot.
 
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First reaction; I want one!!!

Second; subscribe

Third; Call Tim!!!

This is going to be awesome, and I think that it will open up the world of 2 stage to many other people!
 
Here's a couple dry fit views of Interstage coupler so ya can get a better idea of the concept.

DSCN2074.jpg DSCN2077.jpg




And then into the sink for the obligatory "washing of the parts" & the build will begin!DSCN2078.jpg
 
Ah crap- where's the kids when you need to sell one? Just when I say "no more"....THIS happens! *sigh* Guess we're lucky out here it's too hot to fly for a couple of months. The build pile just took an ominous turn...thanks, Jim!
 
First I will build the new fincan. Sand the entire motor mount tube & both sides of centering rings with 80 grit.

Notch the top centering ring on opposite sides for the Kevlar Y-harness.100_9816.jpg 100_9817.jpg



Then cut off enough Kevlar so the Y-harness just comes to edge of fincan. Little over or under doesn't matter. But you want the loop right at edge to give double thickness, so less chance of zippers. Tie overhand knot near the end so you have an attachment loop for shock cord.
DSCN2084.jpg


Slip ends of Kevlar under notches and put about 4-5inches along side of motor mount, to be glued.
100_9828.jpg


Finally encapsulate the Kevlar with epoxy. I'm using the Rocketpoxy on this build. Be careful not to get it all over the MM tube. Fins need to have nice clean areas to be glued too. Put a small fillet of epoxy on top side of CR also.

DSCN2086.jpg
 
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After glue is FULLY cured add a CR on to end of motor mount assembly and insert into fincan. NO glue .......this is just a dry fit so you can insert fins and mark them.
DSCN2087.jpg


Sand any rough edges on fin slots and fins if needed. Insert fins into slots, one at a time and draw line along fin/airframe joint. This mark will aid in showing how much of fin root to sand for fillets....internal & external to aid in glue adhesion.

DSCN2089.jpg

Sand above line approximately 1/2inch......... down to fin root, with 60-80 grit paper. Now ready for installation. Slip back into slots and re-mark lines on fins. When gluing them into slots, the line will show they are tight to motor mount tube. If any line is showing or at an angle, fin is hitting something[Y-harness tails in way of slot] or caught on edge of slot. Lines straight & in position at airframe, indicate a tight fit to MM tube.

DSCN2091.jpg
 
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Sand on each side of every slot, 1/2 inch from edge, for external fillet adhesion.DSCN2092.jpg




Use dowel, PVC pipe, etc wrapped with 60-80 grit sandpaper to reach INSIDE of airframe. Sand in front & back of all slots on airframe where the CR's will be positioned for a good glue bond

DSCN2095.jpg


Be sure to check and see if you hit the mark! If not....sand again. Looking inside you can see the scuff marked rings where the CR's will hit.
DSCN2097.jpg!
 
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I am skimming over most of this, as you should have built the other fin can previously & be aware of the steps.

Kevlar strap is already glued in, so rest of CR's can now be tacked in place for a dry fit. They should barely show in each end of fin slot, they can be lined up externally and tacked in place.
This shot is from the booster fincan.
DSCN0279.jpg

Only difference for the new sustainer is starting from the rear slot, which has been moved farther up. So you cannot rest a CR on the Aero-Pac as before, there will be a large gap between motor retention and bottom CR.
DSCN2099.jpg

The motor retention should be flush with edge of airframe. [give or take 1/4in. either way]
DSCN2100.jpg


Tack CR's into place after stacking and fitting fins. First the upper set.
DSCN0283.jpg

Then the lowers's. Actually it really doesn't matter which set you do first. Just tack them first, remove fins,place assembly into airframe, then insert fins into place checking for proper fit.
If satisfied, remove fins and assembly and glue CR's into place. If not adjust to fit correctly.
Remember keep glue from any area fin will contact!

DSCN0280.jpg
 
Awesome build thread, CJ! How much clearance is there from the Aeropack screw-on ring and the interstage coupler? I've wondered if there was enough clearance, or if it might even be tight enough to add additional rigidity to the stack. Also, how do you plan to separate the stages via the RRC3--actively through a seperation charge or via sustainer motor ignition?
 
Awesome build thread, CJ! How much clearance is there from the Aeropack screw-on ring and the interstage coupler? I've wondered if there was enough clearance, or if it might even be tight enough to add additional rigidity to the stack. Also, how do you plan to separate the stages via the RRC3--actively through a separation charge or via sustainer motor ignition?


Hey Mark, hope ya had a good time back!

Yes, clearance is close. The bigger picture is getting the match wire through that same gap when the interstage coupler is in place should you wish to keep the staging electronics in the sustainer. It's so tight ya need to keep the wire oriented flat against the aero-pac or use 24guage shooter wire run through the conduit, then attach a match after the trip around the AP retention.
It will also be set up for staging below through the interstage coupler.

Since there is only one aux channel, you would have to hook up a separation charge to the same lead as the firing match, if you desired to use one. [unless someone know another way around this, possibly a timer in the interstage in conjunction with altimeter above or just a 2 event timer such as the PET-2 missleworks in the interstage.

All this above is being addressed in the next few posts for you to decide how you wish to configure this.
 
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First Option using conduit in sustainer:

This is a tight fit and during building there is NO room for error. I used steel brake line for the conduit. 3/16 foreign, get it Pep Boys, Auto Zone, etc. Since I'm not injecting internal fillets & using the Rocketpoxy, I went with 3 CR's. Drilled holes, fitted line, filed where needed for better fit & filleted line on MM tube.
You can plainly see with some care it will fit fine.

DSCN2104.jpg


Run conduit to within a 1/4 in of retention flange [part glues on motor mount]. This way end of conduit is easier to "find" when fishing match wire through it. If you cut it off flush with rear CR....good luck fishing wire. If you butt it against retention flange , half the hole will be blocked.

DSCN2103.jpg [Retention crooked, not glued on yet in pic]



Over all pic of my mounting technique.

DSCN2102.jpg
 
First off to make this work I must modify my aero-pac. Since it sits 1/4 inch inside of airframe, I can't screw it shut.

I drilled 2 1/8in holes in my cap .DSCN2121.jpg



So now I can use a finish nail, allen wrench, what ever to screw cap on and off

DSCN2123.jpg DSCN2124.jpg


Here with cap on & match wire in conduit,then bent into motor hole simulating nozzle position . You can see it's do-able but NO room for error. You must be sure everything is centered correctly, and motor retention is on straight. Wire must be laying flat against retention cap.


DSCN2161.jpg









Now with the transition coupler in place & looking down through it.[ obviously before I glued it all together]

It's a perfect fit, but NO room for play. My back up plan is to use 22-24 gauge shooter wire run through conduit & around retention cap, then splice on e-match lead, to motor. That will ensure plenty of room if needed, due to different brands of match wire thickness.
Everything is centered correctly as seen in above pic, but here it looks off center due to optical illusion from taking picture at an angle.

DSCN2162.jpg


All these pictures will blow up quite large by clicking on them 2x which I advise doing & inspecting if you are considering doing this.
I will also be doing the transition coupler for firing motor from booster in a bit, hopefully will have this done to test at UURF in New York [Potter field[ this weekend.
 
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Now that I've explained why and how I did what I did,to make this work...... time to get back on track.

Using the Rocketpoxy, so I use my "double dip" method of tacking fins on to motor mount tube.
First I butter the root edge of fin with glue, then gently place into slot and just barley push into place. Remove fin and butter root edge [bottom] a second time, finally pushing into position.

Essentially doubling the amount of glue internally holding fin to motor mount.

DSCN2111.jpg



On a split fin model, I find it easier to do the bottom set of fins first.....

DSCN2119.jpg

Then use clips,clamps etc and a straight edge [here mixing sticks] glue & align the top set.
 
DSCN2105.jpg DSCN2108.jpg DSCN2112.jpg DSCN2113.jpg DSCN2114.jpg DSCN2116.jpg DSCN2117.jpg Building the interstage coupler:

I first must glue the front CR & Bulk-plate onto the 38mm inside tube for the 54mm bay.
Sand end of 38 tube and one side of CR & bulkplate

DSCN2105.jpg

Tape over center 1/4 hole on one side of BP. It will be filled with epoxy, then drilled 7/16 for match lead latter.
DSCN2108.jpg


Flip over and fill hole with epoxy. Then spread liberally more epoxy around the centering ring.

DSCN2112.jpg

Push 2 rings together. DSCN2113.jpg


Insert 38mm tube. Make sure rings are flush on end & excess glue removed from edges so they will fit inside the coupler later
DSCN2114.jpg

If ya did it right, taped side out...just sitting next to coupler curing.

DSCN2116.jpg DSCN2117.jpg
 
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DSCN2128.jpg DSCN2130.jpg DSCN2140.jpg DSCN2141.jpg DSCN2144.jpg DSCN2145.jpg After the cure drill a 7/64 hole in front BP for match wire.

DSCN2141.jpg

Insert coupler into airframe and mark around it for vent band placement.
DSCN2128.jpg


This mark should be 2.5 inches give or take. Measure another 1/2 in further back, this is where the BP will go. You want the extra room for a nozzle or nozzle cap to clear inside. I'm showing the measurements on the out side for visual. You can slip tube into coupler and measure from the inside and push into place with a ruler as in pic. 3 inches!

DSCN2130.jpg DSCN2140.jpg


For the other end:
cut a section of Kevlar off the supplied length for a Y-harness on the coupler. Tie overhand knot in center for loop to tie recovery shock cord to.

Notch the the remaining CR for 38mm tube on 2 sides.
Slip CR over Kevlar tails with knot tied in ends and onto tube. don't glue yet.
First position the 38mm av-bay tube into position previously described, I tacked in place with a drop of CA from the sustainer side.
Then mix some 5-10 minute epoxy and pour down the gap between tubes.
Now slide the Kevlar and CR into position approximately 1/4 into tube.
Finally do an epoxy fillet on top of the CR. Done with gluing.

This is what it should look like.

DSCN2144.jpg DSCN2145.jpg

all that's left is to fit and mount the end cap for the av-bay [38mm tube]
Add vent band
drill 3 vent holes
 
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This thread has been very helpful to this newbie's Wildman Jr. 2 Stage build!

Is the AP retainer needing to be recessed just because of the Vindicator fins (i.e. no room for top CR to move forward on motor mount)? Since there is plenty'o room for the forward CR on the Wildman Jr. sustainer I was hoping to avoid the hassle of drilling holes in the AP retainer and having to use nails etc. to screw it shut. Here is the dry fit layout. The blue tape on the MM is just to hold CRs and conduit for dry fit into the sustainer BT.
View attachment 142751
You can see the AP retainer would stick out about 1/4" which is much more convenient. Is there any significant reason not to do this? Shooter wire would wrap around flat the same way. The forward bulkhead on the coupler AV bay moves back to leave the 1/2" for nozzle clearance. Edit 25-Aug-13: One reason to keep retainer forward is to leave room on 1" band behind bulkhead to put vent holes for booster AV bay.

Also, I am a little confused on how to use the three wooden BP and how to build the booster AV bay. Any advice, pictures, thread links etc. would be much appreciated. My thinking is to have the booster avionics (RRC3) do the stage separation just after booster burn-out and booster apogee deployment with motor back-up. The sustainer avionics (Raven 3) would do the fail safe air start and upper stage DD.

This might be getting ahead of you, but do you have to notch the interstage coupler so that it fits outside the conduit?

CarVac there is room (barely), so you don't have to notch the coupler. Here is a my dry fit with AP retainer removed to show the conduit against the coupler.
View attachment 142753
You can see the conduit image mirrored on the inside wall of the coupler showing that there is no room for error. My 3/16" drill holes for the conduit on the CRs were right against the MM (more like notches than holes). I am thinking of slightly beveling the aft end of the conduit to guide the coupler and reduce the chances of a hang up during prep.
 
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DSCN2166.jpg DSCN2168.jpg
Is the AP retainer needing to be recessed just because of the Vindicator fins (i.e. no room for top CR to move forward on motor mount)? Since there is plenty'o room for the forward CR on the Wildman Jr. sustainer I was hoping to avoid the hassle of drilling holes in the AP retainer and having to use nails etc. to screw it shut. Here is the dry fit layout. The blue tape on the MM is just to hold CRs and conduit for dry fit into the sustainer BT.
View attachment 142751
You can see the AP retainer would stick out about 1/4" which is much more convenient. Is there any significant reason not to do this? Shooter wire would wrap around flat the same way. The forward bulkhead on the coupler AV bay moves back to leave the 1/2" for nozzle clearance.

Also, I am a little confused on how to use the three wooden BP and how to build the booster AV bay. Any advice, pictures, thread links etc. would be much appreciated. My thinking is to have the booster avionics (RRC3) do the stage separation just after booster burn-out and booster apogee deployment with motor back-up. The sustainer avionics (Raven 3) would do the fail safe air start and upper stage DD.

.


My motor mount tube was a bit short, hence the need for the retainer to be further up. Yours is longer so no need for the mods to retainer.

The 2 small wood rings get glued together then glued onto the larger one to make a "cap" for the av-bay. Since the recovery harness is glued to the sides of av-bay tube, there is no force on this cap.
In my pic I have a small screw eye on cap just to aid removal from tube.

A small screw on side of tube, screwed into to wood plug, holds everything in place.

I used my RRC3 for staging and sustainer deployment & motor eject for the booster...just to keep things simple.

I finally will get to fly it at Airfest & will post results here with more pics & final notes.
 
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Thanks, that makes sense... just like the 3" Wildman 2-Stage instructions. Would be interested in seeing how your RRC3 is supported inside the AV bay. I'm thinking maybe wrapping in foam. Good luck at Airfest!
 
Would be interested in seeing how your RRC3 is supported inside the AV bay. Good luck at Airfest!


Here ya go. I just added terminal block on the existing bay & mounted the RRC3.

I put my sled BETWEEN the tie rods so I have much more room than those putting the sled ON tie rods. Also use # 6 rods instead of 1/4in. giving me plenty of space.

DSCN2171.jpg

DSCN2173.jpg

DSCN2176.jpg

DSCN2177.jpg
 
Thanks again. Very helpful. It looks like the bottom of the sled is not attached to the tie rod below it. For axial Gs do you pad the ends with foam or is that not really an issue?
 
It looks like the bottom of the sled is not attached to the tie rod below it. For axial Gs do you pad the ends with foam or is that not really an issue?

Correct, it cut to fit just under half the diameter of airframe,sits lower in bay , more room to mount stuff on top of sled.

Not an issue, the sled is cut a tad oversize....then sanded to fit exactly into the bay [end to end]
no play or slop. When end caps are on, it does not rattle.
 
I realized one reason to have the AP retainer as forward as possible is to leave more room for booster AV bay vent holes in the 1" band. An additional set of internal vent holes would go on the AV bay tube just aft of the stage coupler bulkhead between the CRs. This keeps open the option of baro based electronics to do booster separation and recovery. Might come in handy since some of the Rocksim motor combos show the booster hitting 4,500' or more. :surprised: So, there would be a set of vent bands on the 1" band above the stage coupler bulkhead for the sustainer motor ignition and a set below to vent the booster AV bay. The sustainer motor vent holes are only needed if the booster separation fails or for simple flights using the sustainer motor for separation, but they will be there for redundancy and flexibility. Any flaws in my thinking here?

Another question is about rail buttons. Should they be on the sustainer as well as the booster? The buttons are only 6 3/8" apart on the Wildman Jr booster (CR to CR) to start with and that seems marginal at best for the two stage stack. Another option is to move the booster forward rail button higher (kind of a pain in a 2.1" rocket, but certainly do-able). Nice thing about the later is no rail button drag on the sustainer.
 
I realized one reason to have the AP retainer as forward as possible is to leave more room for booster AV bay vent holes in the 1" band. An additional set of internal vent holes would go on the AV bay tube just aft of the stage coupler bulkhead between the CRs. This keeps open the option of baro based electronics to do booster separation and recovery. Might come in handy since some of the Rocksim motor combos show the booster hitting 4,500' or more. :surprised: So, there would be a set of vent bands on the 1" band above the stage coupler bulkhead for the sustainer motor ignition and a set below to vent the booster AV bay. The sustainer motor vent holes are only needed if the booster separation fails or for simple flights using the sustainer motor for separation, but they will be there for redundancy and flexibility. Any flaws in my thinking here?

Another question is about rail buttons. Should they be on the sustainer as well as the booster? The buttons are only 6 3/8" apart on the Wildman Jr booster (CR to CR) to start with and that seems marginal at best for the two stage stack. Another option is to move the booster forward rail button higher (kind of a pain in a 2.1" rocket, but certainly do-able). Nice thing about the later is no rail button drag on the sustainer.

You could use Acme rail guides on the booster instead and get whatever amount of spacing you want.
 
You could use Acme rail guides on the booster instead and get whatever amount of spacing you want.

Y'now that might be the ticket. I have some 38 mm ACME guides laying that were just too bulky for a MD project, but they might be a okay for this. Especially if the sustainer gets to go rail guide free. Just looking at them and thinking about the metal on metal going up the rail gives me a "fingernails on a chalkboard" feeling, but I could get over it.
 
The aerotech "conformal" rail guides work great and are plastic if you don't want to use the metal ones. I used the acme ones on a rocket for 10 or so M flights and they worked great.
 
Y'now that might be the ticket. I have some 38 mm ACME guides laying that were just too bulky for a MD project, but they might be a okay for this. Especially if the sustainer gets to go rail guide free. Just looking at them and thinking about the metal on metal going up the rail gives me a "fingernails on a chalkboard" feeling, but I could get over it.

The metal ones really slide easily. They cut right through gunk from sparkies and such, but they don't seem to put much wear on the rails.
 
I was thinking about this the other day-several clubs don't allow metal rail guides because they 'chew up the rails', but in my experience launching exclusively metal rail guides for the last year, I haven't seen any damage whatsoever. I think the issue is that the Acme rail guides have tons of slop room; they're much smaller than the size they need to be. This means that if they're on really, really straight, they don't rub at all, and they don't gouge the rails. However, it (possibly) means that if you put them on crooked, or misaligned, they could actually be fairly far off and the rocket would still fit into the rails-but it would gouge the rails by jamming the sharp edges of the metal into the sides of the channel. It might be the case that the metal guides only work fine if they're very straight.
 
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