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  #1  
Old 02-16-2007, 11:56 AM
SaturnV SaturnV is offline
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Default estes Short engines

Hello everyone. This is my first post but I have been checking out this site for about 6 or 7 months. Lots of good info here. First got into rocketry back in the mid 60's, then got out of it in the late 70's. Now I am back into it and am building a lot of the kits I once owned, and some I could only dream of owning in my youth. So far I have built a Gemini-Titan (PDrocketry), a saturn V (Estes), and with the help of balsa machine service a wac corporal, mini bertha, screamer, midget, skyhook, V2, etc. Now to my question. I wish to fly some of my "S" engine rockets, not with the mini-brute engines but with actual S engines. For the upper stage of my Midget I simply made a little fixture that holds the 1/2A engines and cut them on a saw to the S size. However, Estes stopped making the 1/2A or full A booster engines so I am stumped here. Way back when Estes packed their engines with a little paper cup on top to hold the ejection charge (any of you old timers remember that??) I would make my own booster engines by removing that paper cup and dumping out the loose blackpowder grains. These booster engines always worked in igniting the second stage. Am wondering if I could still do the same by removing the clay on top of current engines . Appropriate safety measures would be taken of course. Anybody ever try this? I should mention that when I was growing up everybody in the neighborhood that wanted booster engines would do as I did and simply modify regular engines. Any other manufacturer of engines besides Estes?? I am basically just re-entering (no pun intended) this hobby and cannot find anything on the web about this. Thanks to all in advance
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Old 02-16-2007, 05:09 PM
Green Dragon Green Dragon is offline
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Well, safety code issues aside ( it is technically illegal to modify ANY motors, including cutting off the cardboard casing to 'short' specs. ) ...

cutting down a 1/2A or A engine to 1.75" short, should pose no hazards, and would fly nicely.

However, you mention pouring out the ejection charge powder and using a regular engine for a booster - although it sounds liek this would still adequately ignite an upper stage engine - the DELAY would still be in place, and would therefor NOT stage at burnout, like a true booster engine would.

I would definately NOT reccomend using a delay engine as a booster, as staging delay would lead to tip-off and non-vertical flights.

~ AL

ps: and welcome to the forum, lots of rocket crazies here, me included, will help each other out as possible, guys teach me lots.
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Old 02-16-2007, 05:41 PM
stefanj stefanj is offline
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If you hunt around, you can still find A10-0T booster motors.

I plan on using them in my Firefly by gluing the motor inside of a "shorty" sized dummy casing.
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Old 02-16-2007, 05:50 PM
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tbzep tbzep is offline
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I will admit that I once took a D12-3 and dug out the clay cap, ejection charge, and delay train one day when I wanted to chad stage a Big Bertha and realized I was out of booster motors. (It was a private launch, BTW.) It worked exactly like a regular booster, but I was paranoid enough about a static charge igniting it while digging the stuff out that I wore my fire gear for protection (trained professional and all that stuff). I only did it that one time because I've always kept a supply of booster motors on hand since then. Would I ever do it again in a pinch? I'll just take the 5th on that.
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Old 02-16-2007, 07:02 PM
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Doug Sams Doug Sams is offline
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Quote:
Originally Posted by SaturnV
I wish to fly some of my "S" engine rockets, not with the mini-brute engines but with actual S engines. For the upper stage of my Midget I simply made a little fixture that holds the 1/2A engines and cut them on a saw to the S size. However, Estes stopped making the 1/2A or full A booster engines so I am stumped here.
Basically, your only choice is Estes, although there are a few Quest B6-0 boosters out there you might could cut down to "S" length.

If you use a cut-down Estes 1/2A6-2 in the sustainer, you should be OK for single stage flights, but for staging, you will want a longer sustainer delay. Otherwise, you're likely to get ejection while the rocket is still moving fast on the way up resulting in a zippered airframe or shredded chute and crash. I zippered my ~30yo Midget 'cause of too short a delay and was mightily bummed.

Unless you find someone willing to part with actual shorty motors, you're gonna have to roll your own. The S motors are pretty scarce. They went out of production around 1972, so they've been gone a long time.

I have a fleet of over 20 Midgets in various sizes and scales, and fly them on everything from 1/8A's to J's. The common motor combos I use with my K-40 clones are A10-0T and/or B6-0 boosters with A8-5 or 1/2A3-4T sustainers.

With the T motors, you take a spent 18x70mm casing (ie, standard size motor) and saw it down to 1.75". Actually, saw it to 1.8" then sand it to the exact length - you want a nice, clean, square end to tape flush to the other motor. Insert the T motor in it and add a couple drops of white or yellow glue. Voila! Home made S motors.

If you use the 1/2A3-4T in the sustainer, try to find some with the all-purple printing on the motors. These are a bit older and work great. Some of the newer ones, with the multi-color printing, have nuclear ejection charges which have been know to break the shock cords and even rupture the airframes

With the standard sized motors, you can, as you have stated, cut them down to length. Both the B6-0 and A8-5 have over an inch of open space you can saw off. I like to stuff a bit of flame proof wadding into the end before I begin sawing just in case the sawing produces a spark which might make things hot Be sure to remove the wadding before you tape the motors together. Also, make sure you scrape, eg, with a small drill bit, the sustainer nozzle to ensure it's clean and unobstructed for staging. One wrap of cellophane tape is the standard for joining the motors.

I love staging and fly lots of them besides my Midgets. (Sunday's outing was four 2-stagers and a cluster.) If you get the motors prepped well, you'll have lots of success.

Here's a shot of my 2.2X upscale Midget just coming up to pressure. That's 3 outboard B6-0's (or C6-0's) and a centerline D12-0 in the booster. I think that's the burn string falling away just below the burn stick. Or maybe it's one of the ignitor lead extensions.


Doug
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  #6  
Old 02-17-2007, 12:18 AM
SaturnV SaturnV is offline
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Thanks guys. I thought about using the A-10-0T engines, but my local hobby shop does not have any and I checked the Estes catalog and they don't make them anymore. Couple of other shops I can hit, will try them this weekend.
Sure wish companies would make a run of these old motors, like some gun companies do. Every once in awhile Winchester or somebody will do a quick production run of some long obsolete ammo.....just to keep their customer base (that had faith in the company and bought their firearm) happy.
I'd like to see the B-14 motors back too!!
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  #7  
Old 02-17-2007, 05:52 PM
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tbzep tbzep is offline
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I'd like to see it happen too. However, I doubt we will ever see the B14 again because the cored motor is more complicated/dangerous/less profitable to make.
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Old 02-17-2007, 08:56 PM
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Gus Gus is offline
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A10-0Ts are currently available at AC Supply.
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  #9  
Old 02-17-2007, 10:28 PM
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Ltvscout Ltvscout is offline
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Quote:
Originally Posted by Gus
A10-0Ts are currently available at AC Supply.

There's that rocketry store down in TX that has them as well. Unfortunately, I don't recall their name. I'm sure Dave will pipe in if he sees this post.
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  #10  
Old 02-18-2007, 10:03 AM
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JRThro JRThro is offline
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Quote:
Originally Posted by Ltvscout
There's that rocketry store down in TX that has them as well. Unfortunately, I don't recall their name. I'm sure Dave will pipe in if he sees this post.

Scott, do you mean Launch Pad 2000?

Here's a link direct to their mini-engine page:
http://www.launchpad2000.com/modrocen-miniengines1.html

(I belong to the same club as Dave and Harvey, the proprietor of Launch Pad 2000, btw.)
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