T' Big Bertha: Is a very old model built in t' 1970s by me brother. Very popular model, you probably have this or one o' its many derivatives yourself. This rocket be t' classic '70s kit. It is big, fat, slow flier with a retro look. This one isn't retro-"looking" though; it's t' real retro thing. It is painted in t' original mid-70’s catalog scheme, but with a lighter - more 50's style - cream yellow. Ahoy! I would prefer t' newer all-black look Estes is showin' now, or maybe some red/white/blue patriotic scheme.
It sure eats a lot o' waddin' with that big BT60 tube! I installed a Nomex cloth so it will never need waddin' again, and a nylon cloth parachute. Begad! I have modified this rocket with me "Iris" altimeter bay, which adds another 2.88 inches in length and 14.6 grams o' weight. (Iris is named after t' Greek god o' t' rainbow. Blimey! She is a messenger o' t' gods, linkin' t' gods with humanity.) This model always seemed t' weathercock a lot for me, me bucko, I hoped that t' extra nose-weight o' t' newly added payload would have helped a bit, matey, but it just slowed it down some more, t' 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 t' Saturn V Apollo spacecraft, matey, and t' famous Spire o' Dublin. Aye aye! But with t' extra weight and drag I added, this slow flier seems t' always be sensitive t' t' wind.
A late ejection on a B6-4 (I should have used a -2), damaged t' engine mount in a high-speed impact with t' mud, so this was re-built with a larger motor mount so she can fly again with D12 power. Well, blow me down! (T' original stuffer-tube was removed.) T' added impulse should get her up in a hurry and t' longer burn time should produce some really high flights, matey, 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 t' Two Liberty Place Buildin' in Philly, t' US Steel Tower in Pittsburg, and t' Chase Tower in Indianapolis IN.
| Flight Date: | 2012-04-01 |
| Rocket Name: | Big Bertha |
| Kit Name: | Estes - Big Bertha {Kit} (1948, 23, 7007) |
| Flyer's Name: | Rich DeAngelis |
| Motors: | C11-5 |
| Launch Site: | Penn Manor School Lancaster PA |
| Actual Altitude: | 361 Feet |
Second attempt with this new motor type for Bertha. This time she flew about as well as t' first time. T' peak acceleration was a bit less at 12.8Gs, and averaged 6.1Gs for t' burn (a little less). Begad! It reached a speed o' 99 mph, also a bit less. After a 4.2 second coast she apogee'd at 361 feet (17 feet less), matey, and dropped 8 feet in 1/2 second before t' ejection fired.
This time t' parachute fully opened and she descended at 12 mph t' a softer landin' in t' grass after a 25 second flight. Well, blow me down! One shroud was caught on t' shock cord knot on t' swivel clip, so t' canopy was a bit mis-shaped. Considerin' me last three flights with failed parachutes, I'll take it!
Succesful test flight o' t' C11-5 motor in gusty winds. Possibly t' best motor for this model, with near-perfect delay times. Comparin' t' C11 flights with t' C6 which have almost t' exact Newton-Seconds o' total impulse, I can see that t' C6 flies about 35% slower and goes about 3% higher because o' t' reduced drag at lower airspeeds.
| Stage | Motor(s) |
|---|---|
| 1 | Estes C11-5 |
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