Wondering about Estes first flight engine recommendations...

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Hank1986

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I am curious what parameters Estes uses in their "Recommended Engines" for first flights. For example, Estes recommends a range of these engines: B4-2, B4-4, B6-2, B6-4 and C6-5 for use in the Big Bertha.

For the first flight, however, the B6-4 is recommended. I wonder upon what criteria they base this choice. Any thoughts?
 

neil_w

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I am curious what parameters Estes uses in their "Recommended Engines" for first flights. For example, Estes recommends a range of these engines: B4-2, B4-4, B6-2, B6-4 and C6-5 for use in the Big Bertha.

For the first flight, however, the B6-4 is recommended. I wonder upon what criteria they base this choice. Any thoughts?
I would say it is the motor most likely to result in a successful flight and recovery under a wide variety of conditions.

Conceivably, motor availability could play a role (B6-4s are very easy to get, certainly moreso than B4s) but I don't know.
 

SharkWhisperer

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I am curious what parameters Estes uses in their "Recommended Engines" for first flights. For example, Estes recommends a range of these engines: B4-2, B4-4, B6-2, B6-4 and C6-5 for use in the Big Bertha.

For the first flight, however, the B6-4 is recommended. I wonder upon what criteria they base this choice. Any thoughts?
Especially for those who've only flown a few (or no) rockets before, it's the motor designed to give sufficient altitude (generally on the low side) to pretty much guarantee recovery. Even experienced flyers sometimes have a tendency to pick a field that's too small or to misjudge wind conditions (which can always be variable). Bertha's unlikely to get too high on a C6-5, but running on half that power increases the odds of: 1) you recovering your rocket instead of it blowing into the weeds/woods/waters, and 2) being able to see all phases of flight, particularly take-off and ejection, so you know how your rocket behaves in general. I have a fleet of tiny "disposable" Wizards from a bulk pack that I toss up for fun or sometimes to check upper wind conditions before launching more valuable birds, especially when i'm using my closest field that I wish were larger. On an A motor, it'll always come home, 90% of the time on a B motor, though I generally lose visual track of it until I see the streamer pop out. On a C motor, in that field, it would be a coin toss if I'd ever see that little rocket again. Bertha's great because she's fat and a low flyer--550 feet listed using a C, with "typical" construction/finishing with the stock 18 mm motor mount. But you can also fit composite fuel 18mm D-motors (e.g., Quest D16-4s) or install a 24mm or 29mm mount for bigger engines to get more altitude. If you don't build so aerodynamically (rounding fin leading edges especially or rough/no paint job), she might not fly as high as possible. I've seen a few Berthas that were built heavy or not so aerodynamically that did better on a C6-3 than the recommended C6-5. If the chute's popping while she's screaming towards home, then use a shorter delay time. If the chute's popping while there's still some upward motion then consider a longer delay. You're gonna love your Bertha!!! And then you need to get yourself a Big Daddy to complete the marriage! I'm not much of a speed/altitude demon and enjoy big fat rockets where you can see all phases of flight without binoculars.
 

messedupryan

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get yourself a Big Daddy to complete the marriage! I'm not much of a speed/altitude demon and enjoy big fat rockets where you can see all phases of flight without binoculars.
I bought a Big Daddy today for this exact purpose. Something to fly with my kids that they can track visually.
 

SharkWhisperer

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I bought a Big Daddy today for this exact purpose. Something to fly with my kids that they can track visually.
You're going to love Fat Daddy!!! Try a D12-3 BP motor first and watch winds--it's got a large profile. You can stuff some potent composite D/E motors into its 24mm mount if you want that will exceed Estes recommended motor specs, and still keep it within sight.

It's a fat rocket that doesn't fly all that high. But if you're feeling gutsy, you can probably get away with a low flight with a C11-3 motor or even (really pushing it) a C6-3 in a plastic adapter. Please do not try a D12-5 though--I saw one pop it's chute about 50 feet off the deck going ballistic once and it survived, but was less than ideal. And I saw another destroy itself when the ejection charge (or chute packing) failed and it came in fast. Big Daddy is as much a classic as the Bertha series.

Have a blast!!!
 
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icyclops

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I would say it is the motor most likely to result in a successful flight and recovery under a wide variety of conditions.

Conceivably, motor availability could play a role (B6-4s are very easy to get, certainly moreso than B4s) but I don't know.
I would agree...
 

SharkWhisperer

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Thx for looking out for a feller ;)
Of course. But it's a great rocket and your kids are going to love it as much as you!

Another potential issue with Big Daddy is the angled/slanted nose cone insertion into the 3" diameter body tube. Some have speculated that (especially if your chute packing is too tight) the ejection charge might have enough force to vent much of it's energy through the gap of the partially separated nosecone but that leak might not leave enough force to completely eject the nosecone and recovery laundry. Then, drag might push the nosecone back on snug on the ballistic return. To avoid this possibility, you can use a hacksaw to cut off a chunk of the angled nosecone insertion end so that it the nosecone bottom is perfectly flat, and glue in a round disc of balsa plywood or craft plywood with a metal screweye through it (and epoxied down tight) as the new nosecone bottom. This would remove the angle and present a flat nosecone end, provide more room in the body tube for your recovery gear, and weight loss/gain would be dependent on your craftsmanship and choice of bulkhead material. This is discussed in at least one other recent thread, but you'll have to search for it. Just sayin'.
 
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