Flight Log - 2013-05-04 - Rich DeAngelis's Big Bertha

The Big Bertha: Is a very old model built in the 1970s by my brother. Very popular model, you probably have this or one of its many derivatives yourself.  This rocket is the classic '70s kit. It is big, fat, slow flier with a retro look. This one isn't retro-"looking" though; it's the real retro thing.  It is painted in the original mid-70’s catalog scheme, but with a lighter - more 50's style - cream yellow. I would prefer the newer all-black look Estes is showing now, or maybe some red/white/blue patriotic scheme.

It sure eats a lot of wadding with that big BT60 tube! I installed a Nomex cloth so it will never need wadding again, and a nylon cloth parachute. I have modified this rocket with my "Iris" altimeter bay, which adds another 2.88 inches in length and 14.6 grams of weight. (Iris is named after the Greek god of the rainbow. She is a messenger of the gods, linking the gods with humanity.) This model always seemed to weathercock a lot for me, I hoped that the extra nose-weight of the newly added payload would have helped a bit, but it just slowed it down some more, the Nomex and heavier Nylon cloth didn't help either, I just made Big Bertha into Big & Heavy Bertha.  With a C6 motor his rocket has flown higher than the the Saturn V Apollo spacecraft, and the famous Spire of Dublin. But with the extra weight and drag I added, this slow flier seems to always be sensitive to the wind.

A late ejection on a B6-4 (I should have used a -2), damaged the engine mount in a high-speed impact with the mud, so this was re-built with a larger motor mount so she can fly again with D12 power. (The original stuffer-tube was removed.) The added impulse should get her up in a hurry and the longer burn time should produce some really high flights, I would expect more than 600 feet at least, possibly 7 or 8 big ones. We will see...

...we did see. It has now flown higher than the Two Liberty Place Building in Philly, the US Steel Tower in Pittsburg, and the Chase Tower in Indianapolis IN.

 

Flight Date: 2013-05-04
Rocket Name: Big Bertha
Kit Name: Estes - Big Bertha {Kit} (1948, 23, 7007)
Flyer's Name: Rich DeAngelis
Motors: D12-7
Expected Altitude: 852.00 Feet
Wind Speed: 8.00 mph
Launch Site: Halifax, PA
Actual Altitude: 777.00 Feet

I have only sent Bertha up on a D12 once before since it had its new motor mount installed, and it was a spectacular flight reaching over 850 feet.  Today I was about to try again but use an even longer delay charge since a -5 was not enough. This was flight number 199 since I was a born-again rocketeer, and I was planning a big launch for #200 to follow.

The rocket took off well and travelled fast and straight up for a beautiful high flight.  The bright yellow Nylon ‘chute opened well and the rocket floated for about a minute in the sky.  As it came down, it drifted West and was caught in the very top of a tall tree, about 50 feet high.  The club’s longest recovery pole only reaches about 35 feet, so there was plenty of space between the tip of the pole and the rocket, with no hope of recovering it.

Big Bertha is now on permanent display 50 feet up on the 7th tree from the entrance on the West side of the field.  Having a Nylon parachute with extra thick shrouds, a Kevlar “screw eye” holding the paper and wood payload compartment, it is not likely to rot and fall anytime soon.  Best I can hope for is the high-quality shock cord to eventually rot and the body might fall to its death or recovery. 

The $70 Altimeter Two may easily survive for years before it falls inside its thick plastic padding wrapped in painted cardboard and covered with a plastic nosecone and plywood bulkhead.  If it ever does fall, I should be able to recover the flight data if a lawnmower doesn't get it first. For now though, after about 17 flights and many adventures, Rest in Space Big Bertha Iris, you will be missed.

Heartbroken, I abandoned my plans to execute flight #200, which was to be the Estes Interceptor on a Apogee D12-5 composite motor.

Three weeks later, after many rainstorms, I devised a plan to retrieve the rocket or at least the payload.  The rocket body was not in the tree, the shock cord rubber broke and the body was nowhere to be found after a substantial search.  The parachute was severely wrapped around a branch and so was the Kevlar leader to the payload, obviously from many windy days.

The altimeter was intact but the battery was dead, after charging I could retrieve the data. The burn was 1.8 seconds long, peaking the Gs at 14 and averaging 3.8 for the whole burn.  It coasted for 5.5 seconds after reaching a top speed of 149 mph, apogee was 777 feet. Then it dropped 32 feet in the last 1.3 seconds and the ejection fired 2/10 seconds too short at 745 feet. It descended at 10 mph before hitting the tree at about 80-90 feet. Flight time was 56.3 seconds – or arguably 504 hours and, 56.3 seconds.

I shot a fishing sinker over the offending branch using a sling shot.  Attached was a few hundred feet of 60 lb. fishing line.  The fishing line was used to haul a heavy rope up and over the branch.  Shaking and tugging would not shake loose the parachute/payload, but eventually the branch broke and it fell to the ground with the payload and parachute.

The payload section was obviously soaked during a few rainstorms, but the plastic nosecone and plywood bulkhead kept the altimeter intact and the plastic padding seemed to keep it dry. The Nylon parachute is definitely useable. Someday I may rebuild the rest of the rocket using the original nose cone, but that might have to wait until I complete another 25 kits in my to-build box.

Much thanks goes to my wife who helped me every step of the way. This terse description makes it sound simple, but it took about four hours to complete this rescue as we had unforeseen problems with every step.

StageMotor(s)
1Estes D12-7

 

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