L3 Build - "Bigger on the Outside" - Ultimate Wildman

Welcome!

You've managed to locate my L3 build thread. The idea to pursue this started stewing summer of 2014 with purchasing beginning October 2015. This is a "classic" Ultimate Wildman. It is green fiberglass with plywood centering rings and the longer payload bay. The kit was part of Troj's collection that he was ready to part with (thanks again, Troj). Various bits and pieces for the project have been accumulating since then via Black Saturday and the yard sale section. The certification flight is planned for some time in 2015, preferably at THOR's site near Jansen, NE; backup location would be AIRFest in Argonia, KS.

Greg Rothman and Bob Brown have agreed to serve as TAPs for my project. Most of the specifics of electronics and recovery have been planned out. I will post the specifics as the build thread progresses.

Thanks for reading,
Doug

Specifications:
=========
Airframe:

Propulsion

Electronics

Recovery

OpenRocket File:
===========
[Update weights and upload]

Parts have been weighed and measured for the OpenRocket design file. Sanding to fit centering rings and sandwiching of rings/bulkheads done. Did I mention the sanding?

Pictures please

Today's progress included sanding of the electronics bay bulkheads and the aft centering rings. The appropriate parts were then epoxied with RocketPoxy5000 and glued.

The aft centering ring is a combination of the stock plywood centering ring and a fiberglass centering ring. I wanted a little extra support of the motor retention and a little insurance against recovery and future motors with a big kick.

The fruit of today's labor.

op:

SinfulDarkLord said:

Pictures please

Click to expand...

A copse of fiberglass trunks.

(L to R: NC shoulder, motor mount, av bay, booster, nosecone, payload, switchband, fins on floor)

And now, the tip of the day:


Wrap a little masking tape on the bolt threads to keep them from getting filled with epoxy.

Doug

Thats more like it lol. Keep up the good work.

Gotta love the early Ultimate Wildman & Darkstars, green fiberglass & plywood centering rings.
For one you can see how good of internal fillets you made because of the translucent green FG.
The plywood centering rings are beefy and allow a perfect anchor for your rail guides. Good luck with your build.

op:

[2015-03-09] Motor retention is next up on the docket. Retention will be wit a flanged Aeropack 98mm retainer. This uses 12 8-32 hex cap screws to attach to the aft centering ring. With my sandwiched plywood / fiberglass centering, the inserts would have been almost impossible to install. I went with 1" hardened steel hex cap screws and pronged T-nuts for an alternative that is unlikely to work loose over time. I probably could have gotten away with 3/4"; there may be some Dremel work in the near future.

Several threads have addressed the issue of attaching the Aeropack so the motor casing doesn't bind up on the motor mount tube. Drilling and assembly was in a staged fashion. The first three were drilled/installed one at a time with alignment checked after each one. A small amount of sanding/grinding with the Dremel made short work of the portion of the T-nut that extended beyond the interior of the centering ring.

More to follow.
Doug

The 98mm flanged Aeropack retainer.


Attachment hardware; stock on right, upgraded on left.


A mock-up of the aft end to check fit with a 98mm CTI motor case.


Satisfactory attachment of the retainer with three bolts. Note the bolts extending beyond the T-nuts; fins are planned to break between two of the bolts.

[2015-03-10] With Monday's successful alignment of the retainer, it was time to finish the rest of the bolt installation. Nine lather, rinse, repeat processes, the retainer was attached. One thing to be aware of; it is usually necessary to have all bolts in the retainer before placing it on the centering ring; there is not enough play once a couple are attached. Bolts were partially tightened sequentially around the retainer twice and the motor casing placed back in the retainer for final alignment. A star pattern of tightening, similar to attaching a wheel to a car, was used for the final tightening. The motor casing was easily installed and removed after tightening. A close inspection revealed an almost imperceptible lip on opposite sides of the retainer, but it didn't interfere with functioning. Approximately 5 grams of RocketPoxy was then used to install the centering ring; care was taken to clean out any epoxy from the inside of the motor mount tube.

Doug

One installed retainer.


The finished retention from the bottom side.


Epoxied and ready to cure.


View of the interior of the motor mount after cleaning up residual epoxy.

[2015-03-11] Tonight was probably the last significant time to work on the Ultimate Wildman for a few days; life occasionally gets in the way. More attention was given to the motor mount. This includes the Kevlar strap and middle centering ring.

A brief interlude regarding the history of the Ultimate Wildman booster section (as I have come to understand it):

• Originally a 4-foot booster section.
• Booster section lengthened to 5 feet accommodate 6GXL cases.

The extension from four to five feet was a welcome design change; however, even my long arms are incapable of reaching the front centering ring from the forward end of the tub. This makes it nearly impossible to use U-bolts on the forward centering ring like I did on my 5" Jart. Back to the Kevlar Y-harness it is. The only downside is re-installation of the shock cord after damage. This will be addressed in a later post.

The centering ring was attached while the RocketPoxy was "Stage 1" - thin and slightly runny. By the time the Kevlar was secured, it was "Stage 2" - spreadable but not runny. By the end of the process, it was "Stage 3" - spreadable, but with some difficulty.

Doug

9-foot section of Kevlar strap. Overhand knot in the center.


Mark the middle centering ring to cut slots for the shock cord to pass through.


Marking fins and strap locations with angle aluminum.


Setting the height of the centering ring to snugly hold the fins.


Centering ring is now epoxied (~5g of epoxy) and the Kevlar straps are attached with a layer of epoxy above and below (~30g of epoxy for both sides).


Tape to protect fin attachment points removed.

Retainer looks great. Good idea to use T-nuts.

glenbo said:

Gotta love the early Ultimate Wildman & Darkstars, green fiberglass & plywood centering rings.
For one you can see how good of internal fillets you made because of the translucent green FG.
The plywood centering rings are beefy and allow a perfect anchor for your rail guides. Good luck with your build.

Click to expand...

Yep - sure wish Wildman would go back to green fiberglass. Then I'd buy from them...

This will be a cool build!

[2015-04-05] With a few days break, I've gotten a chance to do some more work of significance. Up for display first is a 3D-printed fin alignment jig. It's not the most efficient use of plastic, but manages to place the fins well enough after clamping that the tip-to-tip measurement is only off by about 1 mm; this is close enough for me. I had a couple other ideas, but this gives good enough results for me. I did just about max out the X and Y-axes on the print bed. Fit was great; no sanding required. I will consider loaning / bartering this after I'm done with fin attachment; it is a pretty hefty chunk of plastic and took about 16 hours to print.



Doug

[2015-04-05] The locally available screws on the motor retention were a little long, so a quick application of a cutoff wheel brought them down to size. Following that, I epoxied the last short segment of Kevlar strap and the third centering ring. Note the two U-bolts added to the upper centering ring; while not required at the moment, I have had rockets where the strap was damaged and needed replaced. I intend to keep this monster around for a good long time and am trying to make it easier to maintain in the future.

The aft centering ring after shortening the retention screws.


Two U-bolts with plates under to act as backup to the Kevlar strap should it become damaged.


Placement of the third centering ring


More to follow.

Doug

[2015-04-05] In preparation for fin attachment and injected fillets, a rat-tail file was used to make six short slots for each fin. For the most efficient epoxy flow, I center the middle one and put the other two approximately one-third the total slot length from the center. The airframe was also sanded to either side of the slot. Internal sanding for the centering rings and along the fin slots still remain before epoxying the motor mount in place.

FYI, an airframe this large causes a magnificent resonance with the file. It was something akin to a broken turkey call on steroids. Complaints from the family upstairs ensued shortly thereafter.

About 1/3 of the epoxy for internal fillets will be injected into each hole.


Doug

[2015-04-06] My last 'free' day of break; most of tomorrow is already spoken for. It's shocking what you can get done when you have some free time. This morning was internal sanding for centering rings and off to the sides of each fin slot for the internal fillets. I did tie and tape a bit of Kevlar (about 3-4 feet) on one of the U-bolts; this will serve as a safety tether on the motor casing. It is cheap insurance and I like the idea of a dedicated tether rather than adding it on the recovery train where it can muck up the works.

All surfaces were sanded with 60 grit then cleaned up with denatured. 32 grams (should have made 35 grams) of Rocketpoxy was mixed up and applied to the interior just aft of where the forward centering ring meets the airframe. The motor mount was aligned and slowly slid forward until the aft centering ring was just outside the airframe. A thin layer of epoxy was then added to the aft centering ring and slid forward the rest of the way. Frequent rotation occurred while I cleaned up the exterior with denatured as well as afterward.

Two quick clamps were put on the top of the rocket to suspend it to avoid any force on the motor mount. The epoxy on the forward centering ring leaves a bit to be desired, but that won't matter once I seal the rest of it with some epoxy later today. This is one of the first green glass kits I've built in a long time. The extra light inside really makes it easy to QA your work. I'd really like to set up some form of rotating device to encourage the first pour of epoxy to the outside of the centering ring, maybe I'll get bored some time; probably not.

Safety leash for the motor hardware is attached to one of the U-bolts.


Clear confirmation that the forward centering ring is epoxied in. The center ring will get a little CA later to prevent leaks from injected fillets.


The aft end of the rocket upon epoxying it into place.


Looking at the forward bulkhead. Rotation helps spread the epoxy around the edges. More will be poured in later to seal the rest of the plywood bulkhead.


The rocket hanging from the rafters to keep the epoxy where I want it. Pay no attention to the rocketry-associated disarray.


Doug

[2015-04-06] This evening's work focused on fins. And by fins, I mean huge chunks of G10 that would seriously ruin your day if you dropped one on your foot. This didn't happen, but it wouldn't have been pretty if it did.

Fins in place and the edges are marked with a soft copper pipe segment. This is what I will use to pull the fillets later.


The copper leaves light, shiny outlines where it will strike the airframe.


Fin fillet templates are made from the outlines scribed with the copper. These are cut out of masking material on my vinyl cutter.


Templates are in place. This can also be done after attaching fins.


26 grams of Proline4500 (22g epoxy and 4 g hardener) ready to go. All but a few grams was used to attach the fins.


The first fin root is sanded to the lines left by the copper, 'buttered' on the root edge with epoxy and ready to be placed in the slot. The first fin was pretty runny; by the time I got to the third fin, the epoxy was almost ideal for spreading and staying in place.


The fin is carefully slid into place and a quick clamp is put on the alignment jig seen at the far right edge. Repeat until the fins are all attached.


Shot down the motor mount shows a healthy bead of epoxy on all fins. I'd say it is fairly even.


All fins are clamped and curing. The 3D printed fin alignment jig has the fin tips within 1 mm of evenly spaced. I'll take that as good enough. I can't wait to make one for some of the smaller rocket and really put it to the test. I also found that it is just barely tall enough to keep the Aeropack from hitting the ground. This might actually become a small stand for storage.


Doug

Major update. The rocket is nearing completion. I need to attach rails and drill holes on the altimeter sled, drill vent holes, insert rail buttons, and finalize the optional HED (head-end deploy) bay layout which is not necessary for the AIRFest L3 attempt. I have put more time into building and documentation than I have posting.

Some highlights:

[2015-06-06]
View of the first pair of injected fillets. Green glass is a pleasure to work with.

I don't know why the picture didn't rotate correctly. Stand on your head. :wink:

Ends of tubes were sanded square. I wrapped posterboard around and marked this with a Sharpie. Sanding by block and final touch-up using the floor (shown below) gave great results. Joints will not allow a fingernail between the sections.


[2015-06-07]
US Composites epoxy was mixed with carbon fiber for injected fillets. 0.15% by mass seems to be about the perfect ratio.
220 grams epoxy to about 0.33 grams CF for each set of 2 fillets gave good results.


[2015-06-12]
Small squares of fiberglass were used to cover the holes for injecting the fillets


[2015-06-13]
External fillets with Proline 4500. No major departure from the typical methods. 3/4 inch copper was used to shape them.


[2015-08-11]
Sand and epoxy the switchband on the coupler.


[2015-08-12]
Sand the forward interior of the nosecone and spacer disk for the metal tip bolt. Pour epoxy in to a depth of 1/4" and let it cure. Flip it over and fill in the upper side of the disk.


[2015-08-19]
In a flash of brilliance, add the possibility of flying a shorty Ultimate Wildman by leaving out the main altimeter bay and payload section ala Punisher. Drill two holes through the epoxy and string Kevlar through. Tie off and don't glue the nose cone shoulder in.


I'm at the 10 image limit. More in the next post.

[2015-08-22]
Lay out the bulkplates for the av bay. I'll look for longer U-bolts, but nearly everything else is done. I'll add 6-32 screws from the bottom with terminals for the ejection charges (one from each altimeter). 1" PVC plugs will hold up to 10g of FFFF black powder. 1/4" All thread to hold it all together. All hardware is stainless steel.


Cut out a massive altimeter sled. It is currently 16" long, but I may cut it down to 9" to fit in the shoulder for head-end deployment (or just make another).


In the midst of these dates, 6-32 stainless machine screws and pem nuts were installed for the payload-avbay joint and nosecone shoulder-nosecone joint. The nosecone and shoulder joint will also be drilled for 4-40 nylon shear pins when the booster-avbay joint is done. This is waiting on a short switchband to arrive in the mail. I will make another drilled bulkplate with shorter bolts and use that in conjunction with another bulkplate from the avbay to serve as a forward mini avbay.

Primer, paint, a HVLP sprayer and supplies are also on hand but I don't plan on having this painted by AIRFest.

Documentation has also been updated to reflect changes. I will spend some time updating the simulation tomorrow. Ejection charge testing will occur after the forward avbay is done. Motor assembly will be scheduled before I leave for KS under the supervision of one of my TAP members. The goal is to have everything but final avbay assembly, charge preparation and section assembly ready before leaving for Argonia. Flight is planned for Saturday morning.

Doug,
I look forward to seeing this beast in a few weeks!
Bob Brown

What Bob said!

What is the planned motor?

Love the project but I really like the 3D printed fin alignment jig. I would like for these to become available for smaller sizes.

Planned motor is a CTI M2045. A 6G 75mm motor with about 7500 N-s of thrust. Early sims put it around 9,200 with no wind. It should be fairly easy to visually track depending on sky conditions, but will have one of my home-grown Telemega boards in it.

As for the alignment jigs, I printed a smaller one for the Punisher I worked on this summer. It was just a collar that fit around the airframe and halfway on the fins. Light clamping and everything seems pretty well aligned. I don't think I measured the tip-to-tip on that one, but maybe I'll take a picture of it later today. I have a new 3D printer that hasn't been dialed in yet and isn't ready for prime-time printing. Maybe that will be a project post AIRFest. There are a few other rocket bits that need some attention as well.

I've already been doing some work this morning on the altimeter sled. Layout should be complete. I hope to have that and epoxying pem nuts in place today. I did end up cutting the sled shorter to make it transferable to either bay.

Doug

[2015-08-23]
The 1010 railbuttons now are now temporarily on the rocket; I used two of the twelve threaded inserts for the 8-32 screws. I wasn't overly impressed with their beefiness when trying to keep the hole through the fiberglass close to tolerance. One or two ended up with the hex portion for installing stripped out. Problem solved with an 8-32 screw and nut to encourage them in with a little less stress. 1515 railbuttons will be installed next week when the appropriate hardware arrives.

Today's time-consuming activity has been epoxying in the pem nuts for airframe joining. I previously sanded around each pem nut before installing; there are 6 total to epoxy; 3 on the avbay-payload joint and 3 on the nosecone shoulder-nosecone joint. The timing is much like fillets; epoxy, wait, rotate...


Cut a 3/4" circle out of masking tape and place over sanded area surrounding pem nut.


Wrap some electrical tape around a 6-32 screw to match the pem nut diameter; place in nut from inside and snug down lightly.


Apply a glob of epoxy around the area, try to minimize coverage on the tape. (6-gram batches for 2 nuts at a time gave just enough)


Using everyone's favorite epoxy applicator, pull a fillet around the screw. It shouldn't be full radius, you are just evening out the epoxy.


Fillet pulled and some excess epoxy removed. Perfection is not necessary, gravity and heat will take care of that.


Carefully remove the screw and clean any epoxy that may have been introduced when removing the screw. I like to run a clean screw from underneath.


Remove the tape and add a little heat to encourage a smooth surface and speed curing. (I'm working in a cool basement)


The pem nuts can now take a little more abuse before popping out; just a little insurance against minor mishaps.

I have also laid out the drill pattern for the altimeter sled and will be tackling that in a few minutes. Recovery harnesses and chutes are set off from the collection. I put in a McMaster order late last night for 4-40 pem nuts, longer U-bolts and 1/4-28 inserts for the 1515 railbuttons. The chute protector for the main will hopefully show up early next week; I don't think there will be any more orders needed for this project.

Doug

Very nice build, I am definitely loving this build.

[2015-08-24]

A 1.5" long switch band arrived today and was subsequently epoxied on the HED av bay. Same process as for the main av bay.


4-40 pem nuts for mounting electronics should arrive either Tuesday or Wednesday.

Work remaining to be done:

• Drill vent holes
• Drill and install 4-40 nylon shear pins
• Install and wire posts for charge initiators
• Countersink airframe screws
• Install 1515 rail buttons
• Install electronics pem nuts
• Bulkheads for HED av bay
• Ground testing

All in all, there is really only a mopping up of some loose ends.

Doug

[2015-08-25]

Tonight saw the hole drilling and installation of shear pins. The same set of shear pin holes can be used in full-length or HED mode. 7/64" seemed just a bit loose for the 4-40 nylon shear pins, but they will be fine once I shim up the shoulders with a bit of tape for flight and exercise caution when moving this behemoth around.

The first time it is externally flight-ready. (Recovery, av bay lids and motor are missing.)


This project has come almost full-circle; a new take on an old photo seemed appropriate.


Remaining:

• Avbay and airframe vent drilling
• Countersink 6-32 screws for airframe
• 4-40 pem nuts on sled (arrive Wed.)
• 1515 rail buttons (arrive Wed.)
• Longer U-bolts (arrive Wed.)
• Drill HED av bay allthread bulkhead
• Make blank bulkhead for HED av bay
• Install recovery system and ground test

After that; a trip to Argonia, KS to light this candle.

So say we all...