jump to navigation

Yet Another Way to Fail When Flying Rockets November 28, 2017

Posted by rluhman in Rocketry, Technology.
Tags:
add a comment

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 (more…)

Advertisements

Warlock Repairs October 27, 2016

Posted by rluhman in Rocketry.
add a comment

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.

Creating Steam-Bertha August 15, 2016

Posted by rluhman in Rocketry.
Tags: ,
1 comment so far

001When I received the March/April issue of Sport Rocketry I noticed the headline on the cover, “Steampunk Rocketry Designs and Techniques”.  That sounded interesting so I opened the magazine to the story and immediately saw some amazing looking rockets.  I dove into the article and each paragraph started my mind swirling off into different directions thinking how I could make something that might look as interesting as those in the article.

Rather than start working on a new rocket to create my first steampunk example, I looked at my fleet of tired rockets that I seldom fly anymore.  I was drawn to my Big Bertha that I had built many years earlier with a three engine cluster.  It was sitting there with a rather ugly plain blue finish.  No markings or anything else, just solid plain blue.  Yes, this should work, I’ll convert my Big Bertha into Steam-Bertha!

Using the article as inspiration and a guide to begin sourcing the parts I would need, I started getting my materials together.  First I got a couple of manila file folders for the heavy paper that I’d need for the straps that the “rivets” would go on.  Now for the “rivets”.  I went to Michael’s and picked up a sheet of half-round pearls with sticky backing.  I’m not sure what other crafters use these for, but for me they were going to become my rivet heads.  I also found a few cards of pre-punched cardboard centering rings in my Estes rocket parts stash.  Those could be used as portholes.  Also in the stash, were some extra launch lugs that I could turn into external piping to disguise the actual launch lug that was already on the rocket. (more…)

Building the Interceptor-E January 13, 2009

Posted by rluhman in Rocketry.
Tags: , ,
add a comment

Well, I had to do it.  I took the Hobby Lobby 40% off coupon and bought an Estes Interceptor-E.  Of course, I made a couple of mods.

Engine hook

Re-enforced engine retainer

First, I reinforced the area directly behind the forward end of the engine hook.  Hopefully that will prevent the hook from being ripped aft when the ejection charge fires.  Sound weird but I’ve had it happen before.  Some of those ejection charges are rather energetic.

Forward ring mods

Modified coupler and forward centering ring

Next, I drilled a couple of small holes in the forward centering ring to attach my kevlar shock cord to.  I don’t like gluing the shock cord to the side of the tube.  I also cut about 3/4 of an inch from one end of the tube coupler to use as a block against the forward centering ring.  Since the centering ring is made of plastic, I know epoxy doesn’t stick to it as well as it does wood or cardboard.  The block is epoxied ahead of the centering ring to help hold it in place just in case the epoxy holding the centering ring gives way.

(more…)

Viper 4x Rises From The Ashes (Again) January 6, 2009

Posted by rluhman in Rocketry.
Tags:
add a comment

It looks like my EAC Viper 4x will fly again.  After spending the last 4 months looking at the remains, I just couldn’t throw it in the trash.  90% of it is still intact.  The main tube only had the forward six inches crushed in the LDRS crash.  The rest of it looks perfect.

There was a small amount of internal damage.  The forward centering ring had popped loose from the tube.  I can easily repair that.  But since I will have to add back the six inches that were crushed in the crash, I won’t be able to use the altimeter setup I had built into it.  It will go back to motor ejection for recovery system deployment.

But, since the tube is now glassed I should have less of a problem with zippers.  That assumes that I can get the motor delays worked out correctly.  Maybe I need to get the EFC-01 from Aerotech or the new accelerometer based one from Giant Leap.  I’ll have to look into that.

Anyway, look for the EAC Viper 4x to make it’s return to flight at our March club launch.  Keep your fingers crossed.