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SteveA

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Here is the design. I need the quad 24mm to provide enough lift to reach the desired altitude to accomplish what I want to do. (collect airborne bacteria at high altitudes) However, as you can see from the sim flights that breaking below 29mph at deployment is tough. I did it once, but it, I'm pretty sure that it was an anomaly. So, do you think a nylon chute along with nylon chord along with a heavy elastic shock cord capable of withstanding the forces exerted on the recovery systems at speeds above 20mph and below 30? If not, any suggestions to the design that I could squeeze out this altitude with it carrying a small altimeter like an Altimeter2 and a collection system?

Cluster A.jpg

Thanks as always for your time.
Steve
 
Steve-I'm unsure of your other concerns, but a common trick to lessen recovery shock is to go with a longer recovery train. I've used small rubber bands on bundled sections of elastic so the deployment 'sequences' with less chute opening shock transmitted because the delay gives everything a chance to slow down thru aerodynamic drag. I really hope this helps. Props to you for an actual working payload.
 
I agree with Rex on a single 29mm composite motor over your 4 motor black powder cluster. A single motor system is inherently easier and more reliable.

Need altitude? With a single 29mm motor, you can use a smaller diameter airframe. Smaller diameter rocket goes higher given the same motor. An Aerotech Barracuda (1.9" airframe) will hit 1500' on an F20 motor.
 
Steve-I'm unsure of your other concerns, but a common trick to lessen recovery shock is to go with a longer recovery train. I've used small rubber bands on bundled sections of elastic so the deployment 'sequences' with less chute opening shock transmitted because the delay gives everything a chance to slow down thru aerodynamic drag. I really hope this helps. Props to you for an actual working payload.

I think this is the way to go. The 29mm sounds great, but I have the 24s on hand. (plus I've never used the 29s before.) I hope this all works out. I kinda excited to give it a try. I'm trying also on a smaller scale with AGLs at about 300 or a little more. Thanks for all the advice guys.
 
29s are actually easier to assemble than the 24s since it is much harder to get the O-rings mixed up :). or you could go with a single use motor. w/ the Ds you're looking at approx. an F48, so an F50 should suffice for altitude (plus one F50 weighs less than 4 bp Ds).
Rex
 
29s are actually easier to assemble than the 24s since it is much harder to get the O-rings mixed up :). or you could go with a single use motor. w/ the Ds you're looking at approx. an F48, so an F50 should suffice for altitude (plus one F50 weighs less than 4 bp Ds).
Rex


Okay, this going to be a dumb question, but the 29s use the same style of motor mount except a BT55, correct?
 
tis a fair question, basically a motor mount is a motor mount they are all pretty much the same style (apart from size), however you will need a 29mm mount tube(bt55 is too big). they can be purchased from a number of sources (Apogee and Loc just to name 2) I think BMS might carry them too. also needed are a pair of centering rings (can be cut from 1/16" non corrugated cardboard assuming TTW fins), and a motor retainer. the easy to use retainer from Estes would work nicely https://www.estesrockets.com/rockets/accessories/engine-mounting hope this helps,
Rex
 
The rule of thumb is below 25 fps for LPR and 50 fps for HPR (stronger construction).
 
Another source for a 29mm motor retainer is a kids meal milk container from Wendy's or Burger King. Cut off the top 5mm (at the convenient notch), the cut the threaded portion of the neck off (behind the "rear" ring), sand as needed, and epoxy the threaded section to your motor tube. You'll need to cut a hole in the milk container's cap. The lids come in brown (chocolate) or white.

Here's a shot showing two of them (the 2nd being used as a centering ring) for my D-Region Tomahawk, and another showing the motor in place...

13530814115_0a07d43b85.jpg
13505320574_25d2e7a51a.jpg


The white milk at Burger King is nasty though (nonfat). Their chocolate is actually not bad. Can't speak to Wendy's milk... My niece was drinking the milk, and I snagged the bottle when she was done.

Caveat on the Milk bottle idea... It fits Estes' 29mm Motor tubes beautifully (without modifying the tube). I just checked, despite being thicker, Sunward's 29 mm motor tubes will fit the Estes 29mm Motor Retainers (without modification of the tube). If you want to use the milk bottle retainer on Sunward tubes, you'll need to remove a layer or two of the paper.
 
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Very interesting! Okay, you guys have convinced me. I'll give this a try with a 29mm. I've wanted to make the crossing for awhile, I guess now is as good of time as any.
 
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