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: | 2012-06-30 |
| Rocket Name: | Big Bertha |
| Kit Name: | Estes - Big Bertha {Kit} (1948, 23, 7007) |
| Flyer's Name: | Rich DeAngelis |
| Motors: | C6-3 |
| Expected Altitude: | 380.00 Feet |
| Wind Speed: | 10.00 mph |
| Launch Site: | Fort Indiantown Gap, PA |
| Actual Altitude: | 328.00 Feet |
I needed to end on a more spectacular flight, so of course I had to bring out ol’ Bertha. I love how she flies on a D, but didn’t want the 800+ feet it would make, the winds were just getting too much. In hind-sight I should have used a C11, but I already prepped her with a C6. The choice of the C6 was risky, and a stronger, steady wind was building. The C6 normally just doesn’t have enough git-up-n-go to prevent serious weather cocking, as I learned from previous bad experiences. I had to hold the launch for a good 5 minutes before it calmed for a second.
She flew great. The C burned for 1.9 seconds and got her going to 77 mph. Acceleration peaked at 6.2 Gs and averaged 1.8 Gs for the burn. After burnout she coasted straight up another 3.5 seconds to 319 feet. The ejection was early but OK (a -5 would be way too much in these winds). I honestly don’t know why she didn’t turn in to the wind like always. The ejection came as it was starting its turn, 6/10 second before apogee. She tumbled a bit and then peaked at 328 feet. The parachute unfurled well and she coasted down at 9 mph, landing within about 300 feet, ending a flight of 28.3 seconds. I thought that was enough for the day, but then I ended up doing one more.
| Stage | Motor(s) |
|---|---|
| 1 | Estes C6-3 |
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