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  #41  
Old 11-02-2016, 10:12 AM
cudacrazy72 cudacrazy72 is offline
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Oh ok. I will check the instruction to see if it specifies where the CG is suppose to be. Thanks for the help.
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  #42  
Old 11-02-2016, 10:37 AM
John Dyer John Dyer is offline
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Quote:
Originally Posted by cudacrazy72
Oh ok. I will check the instruction to see if it specifies where the CG is suppose to be. Thanks for the help.



I'm thinking the info should be there. The idea is to check the CG with the heaviest motor you will use (E30) - that should tell you whether or not you need to add clay.


Enjoy the build!

I have one model in painting stage (from the previous release), and will be working on another build from the latest release - planning on a conversion for a Saturn V Skylab.


John
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  #43  
Old 11-27-2016, 03:31 PM
johnpursley johnpursley is offline
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Believe it or not, the old K-36 Saturn (with the 3-motor or D option) would actually fly just fine on just TWO C6-3s if one happened to not ignite. Don't ask me how I know that. In fact, it probably flew better on two C motors because two C6 motors have more total impulse than an single D-12 (though it was the slightly more "potent" though less reliable D-13 that was initially used in the old Saturn).
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  #44  
Old 11-27-2016, 04:07 PM
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Quote:
Originally Posted by johnpursley
Believe it or not, the old K-36 Saturn (with the 3-motor or D option) would actually fly just fine on just TWO C6-3s if one happened to not ignite. Don't ask me how I know that. In fact, it probably flew better on two C motors because two C6 motors have more total impulse than an single D-12 (though it was the slightly more "potent" though less reliable D-13 that was initially used in the old Saturn).

The 1/70 Saturn 1B was originally a 4 engine cluster and the A8-3 was a recommended motor. The rocket is listed within 0.04 oz of the weight the Saturn V, but I bet most 1B's were/are heavier due to the way most folks glue and paint them. Four A's are the equivalent of a single C motor. We've flown ours on 4 B's (equivalent to 2 C's), but we never had the courage to try four A8's.
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  #45  
Old 11-27-2016, 06:15 PM
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I'd bet a 4x18mm cluster flight of a 1/70 K29 Saturn 1B on two B14-5's (or 2 B8-5's) and 2 C5-3's would make for a neat/interesting flight.
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  #46  
Old 11-27-2016, 06:29 PM
johnpursley johnpursley is offline
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Default Building The Old Estes Saturn IB

Yes, the 1/70 Estes Saturn IB had a 4-engine cluster (it was never offered with any other option...even after the D motors were released). What a memory-maker! And, it DID fly surprisingly well even on four of the "old" A.8-3 motors...and even better on the "metric" A8-3 which had slightly more impulse and a much higher peak and average thrust. The originally recommended A.8 (that's A point 8...it was the pound system) had about half the peak and average thrust as the "metric" A8 (no point before the 8) of 1968 through today (though the old A.8 did have almost twice the effective thrust duration). Plus, we tended to fly in "better" weather conditions as well as launching them straight up, waiting for calm days to fly the "big" models. Today, many modelers fly big, heavyweight models in any condition that exists and hope for the best (and blame the motor or the model manufacturer for design faults when they prang or "zipper" a model).

I don't recall specific instances of not getting a full cluster of 4 A motors to light (I'm sure it happened to me but I just don't recall specific instances) but I do remember when flying a Saturn IB on C6-5 motors in high school only lighting up two and it flew just fine though it was way past apogee when the recovery system deployed. I had the same "two engine" experience flying the 3-engine Saturn 5 though its wasn't as harrowing because of using C6-3 motors rather than C6-5s. I even recall "mixing" motor types on the old IB and it just seemed to fly fine.

I think people forget that modelers, particularly those in the hobby since before, say the mid-'70s, built rockets (and just about any other kind of flying model) appreciably different than than today. Today, they simply build significantly heavier...it's a fact. Gobs of Epoxy, "reinforcing" here and there. Heavy fabric recovery systems. Layers and layers of primer and paint. Fiberglassing...and on and on. Remember, in the '60s and most of the 70s, most modelers used nothing but white (and sometimes yellow) glues. CA was almost unheard of (and not suited to the materials used) and epoxies were messy and expensive (still are!). Plus, whether you bought from a hobby shop or direct (almost the "only" sources for model rockets back then) the mantra was to keep weight down while keeping strength up. This wasn't the "gospel" just for model rockets but for EVERY type of flying model. This was hammered home by publications like Model Rocket News (which if you EVER mail ordered from Estes you became a "subscriber" seemingly for life), Model Rocketry and The Model Rocketeer...and even the model aircraft publications that occasionally had model rocket articles. Following the instructions back then, it was almost impossible to build significantly overweight and what minor "overweight" instances that might have resulted was usually well within the safe performance capabilities of the recommended motors.

There were likely only a relative handful of the old IB that weighed more than 10 ounces...well within the lift capability of even the old A.8 motors. And, I'll just about bet that most were flown on B motors...especially after they saw how the model would "streak" (relatively speaking) off the pad. I built a twin D12 Saturn IB once. Talk about memories! And thanks for the Semroc Saturn IB today!
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  #47  
Old 11-27-2016, 06:41 PM
johnpursley johnpursley is offline
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Quote:
Originally Posted by ghrocketman
I'd bet a 4x18mm cluster flight of a 1/70 K29 Saturn 1B on two B14-5's (or 2 B8-5's) and 2 C5-3's would make for a neat/interesting flight.


Holy Cow! What a "vision." I remember almost being "afraid" of the B14 motors after putting them in something like an Alpha or WAC Corporal. Those models almost literally disppeared off the pad. It would have been "glorious" on C5 motors. I wish we had B14 and C5 motors still available today.

Anyone remember the B16 from Estes (I don't) from about 1962? It had an average thrust of 16 pounds and burned for less than a tenth of a second. Talk about a tiny sledge-hammer motor!
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  #48  
Old 11-27-2016, 08:17 PM
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I've flown the 1B on several combinations, built with removable mount. Single D12, 4 B's, 3 C's to this date. I actually like the slower liftoff of the single D12 better. It's still too fast for scale liftoff, but closer to the slow majestic liftoff of the Saturns.

I can't imagine the altitude of the 1B on four A8's, maybe 75 ft? Thank goodness the 3 second delay is really 2 seconds! The single D12 probably hits around 100 ft, barely above the tree tops with the heavier removable mount and museum quality finish of our model. A stock built one might get 120 if one doesn't weight it down with a slick finish.
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  #49  
Old 11-27-2016, 09:09 PM
johnpursley johnpursley is offline
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Quote:
Originally Posted by tbzep
I've flown the 1B on several combinations, built with removable mount. Single D12, 4 B's, 3 C's to this date. I actually like the slower liftoff of the single D12 better. It's still too fast for scale liftoff, but closer to the slow majestic liftoff of the Saturns.

I can't imagine the altitude of the 1B on four A8's, maybe 75 ft? Thank goodness the 3 second delay is really 2 seconds! The single D12 probably hits around 100 ft, barely above the tree tops with the heavier removable mount and museum quality finish of our model. A stock built one might get 120 if one doesn't weight it down with a slick finish.


We're two birds of a feather when it comes to scale, it seems. I'm a notorious "low and slow" flyer when it comes to scale models. Altitude doesn't mean a flip to me..."it is what it is" so long as it's a nice, safe, successful flight.

Though it's been years since I flew a IB on A motors it probably did hit around 100 feet or so (about twice as high as the ball park lighting on the field I normally flew from). Also, "way back then" delays actually seemed to run a little long. Some people kind of stick their noses up at 100 feet (as well as at "low and slow") but I personally don't care (doesn't sound like low and slow ruffles your feathers, either!).
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  #50  
Old 11-27-2016, 09:22 PM
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Quote:
Originally Posted by johnpursley
We're two birds of a feather when it comes to scale, it seems. I'm a notorious "low and slow" flyer when it comes to scale models. Altitude doesn't mean a flip to me..."it is what it is" so long as it's a nice, safe, successful flight.

Though it's been years since I flew a IB on A motors it probably did hit around 100 feet or so (about twice as high as the ball park lighting on the field I normally flew from). Also, "way back then" delays actually seemed to run a little long. Some people kind of stick their noses up at 100 feet (as well as at "low and slow") but I personally don't care (doesn't sound like low and slow ruffles your feathers, either!).

Not a bit ruffled! In fact, I have built up a small fleet specifically for that purpose so that I can do school demos on something more than a B motor. I've got several 2.6" models with 1/4" thick fins that fly well on C11's or D12's and of course the Saturns. My son has a nice cardstock Little Joe II that flies on 18mm motors and we've done gap staged Aerobee Hi's and the like that staged at less than 20 ft on some of my special A8-0 motors before they were re-released. I've also "manufactured" some nice 1/4A3-0T's for my Mini Brute Beta to stage just above the launch rod!
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