Wild Thing Vintage Kit Build

I haven’t worked on any flying rockets lately, and with the possibility that I might be able to get vaccinated in the next few months, I thought I should work on a new high power rocket.  I went through my collection of kits and picked an old kit that I bought from a fellow club member many years ago.  It’s a kit by Vaughn Brothers Rocketry.  They started in the mid to late 1990’s and folded sometime in the early 2000’s.

It is an interesting design.  It has a central 38mm motor tube surrounded by seven 29mm motor tubes.  It is designed to be flown on the single 38mm motor or a cluster of 29mm motors or both.  The thoughts of flying a cluster intrigued me.  But with safety considerations, it seemed that the safest way to fly the cluster would be to airstart the 29mm motors after the 38mm got it into the air. But, these days you really need a controller that can sense tilt so you don’t start the outboard motors if you are not near vertical.  Plus, the 29mm motor tubes are mounted flush to the 38mm motor tube.  That leaves little room for positive motor retention.  I’ve pondered those problems on and off for a couple of years, and I have finally decided that I just don’t want the complexity and multiple points of failure beyond what a normal rocket has.

This left me with what to do about the outer tubes.  Enter my new 3D printer.  I have designed a false rocket nozzle that will fit in the 29mm tube and surround and hide the central 38mm Slimline motor retainer.  I’ll print 7 copies of that and install them in the rocket.  That should give the rocket a nice interesting look and solve the cluster ignition problem.

So with that major problem out of the way, on to the build.

Here are the parts in the kit.

Mike, the club member that sold me the kit, had already peeled the main body tube and he even threw in the fiberglass for it.  Here is a close up of the centering rings for the motor mounts.  You can see how all the tubes are going to be very close together.

To get a small amount of clearance for the fake nozzles, I wrapped the end of the 38mm motor tube with some masking tape.  That will move the 29mm tubes out enough to clear the Slimline retainer that I’ll be using on the 38mm tube.

With that done, I started putting the tubes in the centering rings.

I’ve done this a couple of times before when trying to solve the above mentioned problems.  The rings need to be kept in a good alignment to get all the tubes in.

Here is a closeup of one of the fake rocket nozzles.

With the tubes in place (nothing is glued yet) I put the Slimline and a nozzle in place to check for clearances.

Just enough room.  The centering rings need some sanding to fit nicely into the main body tube.  I’ll do that after I glass the main tube.  Before I do that, I need to sand the tube to get the major fuzzies off (you can never get all the fuzz off).  I then applied some CA glue to the ends to harden them and also to repair a couple of minor dents on the ends.

Now I need to actually glass the tubes.  First I need to get over to West Marine to get some new pumps for my resin and hardener.  The pump in the resin can seems to be permanently attached now and the hardener is a black orange color so it appears to be past its prime.  The cans didn’t have much left in them anyway and it has been about 5 years since I last used them.  I have trimmed the fiberglass and marked a start line down the main tube, so I’m ready whenever I get the pumps and have some time.

I’m also working on a new plastic model (a BanDai 1/72 scale X-Wing), so I’m dividing my time between this project and the X-Wing (and whatever life decides to throw my way).  More to come.  Thanks for looking.

LDRS 38 Club Project

LDRS is an annual gathering for high power rocketeers from all over the country and a few from foreign countries as well.  This year was LDRS 38 hosted by the Kloudbusters of Wichita Kansas.  They are one of the best clubs in the country for large launches.  They have hosted several LDRS launches and have it down to a fine art.  Which is good because this was the largest LDRS ever.

At the last LDRS held at the Rocket Pasture, LDRS 30, the club built a two stage scale version of the Nike Asp sounding rocket.  It flew well until time to ignite the second stage.  It didn’t ignite!  The recovery system worked properly and we got all the pieces back.  We vowed that the next time LDRS was here we’d try again.

That time came last week at LDRS 38.  Members pitched in and prepared the motors loaded them into the Nike booster and the Asp second stage.  Electronics were prepared and all recovery devices were packed and loaded into their respective stages.

Then we departed for the away pads and to get approval of the Range Safety Officer to fly.  One small problem getting RSO approval, he didn’t like our electronics set up to assure that the second stage would light only if the rocket was still within a few degrees of vertical.  We worked that one out.  Bob Brown the LDRS leader took one of our members back to our camp site to get the laptop so we could reprogram the electronics.  After a few minutes all was well and we headed out to the pad to get the rocket loaded for launch.  Time was ticking down as our FAA waiver only had about 20 minutes left.  We finally got it loaded with just a few minutes left.

The countdown proceeded well and then with a loud roar off she went.  Staging looked beautiful just like last time.  Then the Asp second stage lit and off we go.  Looking good…for a few seconds.  Then the smoke trail changed a bit.  That didn’t look quite right.  But she is still going up.  Wait, the second stage parachute should be out.  Oh, there it is.  That definitely is not right.  There is nothing under the chute.  Plus it should be a lot higher.  We definitely had a problem.  Then we noticed a large section coming down with no chute just trailing some cords to the east.  No sign of the rest of the rocket.  The Nike booster came down just fine.  No problems there.  Now we need to find the as many parts as we can.  The radio trackers came out and then the nose cone was found, but still no sign of the rest of the rocket.

From studying the pictures, we definitely had an anomaly shortly after staging.  Our theory is that as the rocket went transonic or just supersonic we lost a fin.  That caused a deviation from the flight path that increased the angle of attack.  This over stressed the airframe and it broke up.

At least we got the booster back.  I’m sure at some point in the future we will try another club project, but for now we’ll take a break.

Still it was a great LDRS 38, mostly good weather and lots of great flights.

Yet Another Way to Fail When Flying Rockets

Jolly Logic Chute Release

Early in 2016 I bought a Jolly Logic Chute Release.  The device is about the size of a small matchbox.  It allows you to turn any rocket (that the device will fit into) into what is essentially a dual-deploy rocket.  I have several 2.5  to 7 inch diameter rockets that deploy their parachutes at apogee (the highest point of the rocket’s flight).  Depending on the altitude the rocket reaches and the wind it can result in a long walk to retrieve the rocket.

Enter the Jolly Logic Chute Release.  This nifty little device uses a rubber band and pin that wraps around the folded parachute preventing it from opening.  Then when the rocket descends to a pre-selected altitude the pin will release and the parachute will unfurl and the rocket will land safely at a distance that is much closer that it would have otherwise.  I used it quite a bit during the 2016 flying season and had only one failure when the rubber band released from the Chute Release, but somehow entangled in the parachute which caused the parachute to fail to open.  I have avoided stretching the rubber band that tight since then and have had no problems.

That is until this last flight in November 2017.  I had missed all the 2017 season due to back problems, but I finally seem to have that managed and I went out fly on the last launch on the year.  I carefully folded the parachute for my LOC Precision Minnie Magg and wrapped the Chute Release rubber band and pin around the parachute and locked in into the other side of the Chute Release.  I then did my usual shake test to be sure the parachute would not slide out from the rubber band and everything was fine.  Out to the pad I went and we launched it on an Aerotech I161 motor.  It boosted beautifully into the clear November sky, arced over popped the nosecone and bundled parachute out at apogee.  It fell down to abour 400 feet when the Chute Release did its job and released the parachute which opened perfectly and it landed a few hundred feet from the pad.  What a great way to end the season.  A perfect flight.

At least it was until Continue reading “Yet Another Way to Fail When Flying Rockets”

Warlock Repairs

I thought I’d publish a short post on repairing my Warlock after the 2015 High Frontier launch.  I flew it in the Warlock Drag Race and while the up part was just fine, the landing was not so much.  I landed on the asphalt runway and one of the composite fins took the brunt of the landing.  It pretty much crushed the lower corner of the fin and then started to splay the fiberglass skin of the fin apart.

I might have been able to repair it but it would have been a very weak fin and probably would not have withstood another landing without taking damage again.  Instead I decided that my best route would be to cut the current fin off at the body tube and graft another one into place.

These fins are through the wall type fins, meaning that they extend into the body tube and are glued to the motor mount on the inside of the rocket.  I didn’t want to try and remove my rear bulkhead in order to gain access to the fin root, hence my decision to cut the fin off at the outer body tube and graft a replacement on at that point.

In order to provide some strength I decided that I would take my new fin and add a tang that would fin into a clevis that would be put into the part of the fin that was still inside the body tube.  I got some birch plywood that would fit into the composite material between the fiberglass skins.  I decided how deep I wanted the tang to be and cut the plywood accordingly.

Now I needed to remove the Nomex  honeycomb where the plywood tang would go.  I got my Dremel tool out and put in a straight router bit and started removing Nomex.  When I got the depth I thought I needed I pushed the plywood into the space to check the fit.  After several iterations of routing and checking, I finally had the clevis done.  Now I had to do the same thing to the new fin in order to place the tang.

Once that was complete I mixed up some West Systems epoxy to put the tang in the fin. I wiped the excess that oozed out of the slot and set it aside to set up.  The next day I used some more West Systems to glue the new fin into the piece that remained in the body.  The next day I used some 30 minute epoxy to add new fillets to the fin and the process was complete.  I did do a test flight at Leonard to make sure the new fin was as strong as it looked.  The test flight was fine.  It even landed on the repaired fin with no damage.  Now all that was left was to fix the paint job.

At least that was what I thought.  I later found a crack around the circumference of the bulkhead in the nosecone.  Now I need to stabilize that before I can fly it again.  I’m thinking of using three flat head wood screws to hold the bulkhead in place and then put a new epoxy ring around the bulkhead hold everything in place.  Hopefully it will be ready to fly at the start of next season.