Recovery for a Wildman 3X Andromeda

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Wally Ferrer

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As a proud owner of a new Wildman 3X Andromeda kit, I am now faced with how to do the recovery. The up part should be pretty simple with a 54mm inner/main tube that can handle a wide range of motors. My question is how would you do recovery? Traditional dual deploy with drogue at the tube split, main coming out the nose? Or keep that long tube together, like the original, deploying only a main out the nose end, maybe a JLCR if going big motor/high altitude? I haven't done any calculating on the tube volume to rule out motor ejection/nose main only, but likely it will be electronic ejection if only to have a more manageable ejection charge size. Aesthetically I like the idea of just the nose cone separating and parachute coming out. The recovery attachment points aren't quite clear to me yet, regardless of whether dual deploy or single, so ideas and opinions are solicited. I didn't do a poll because my experience is way too limiting to craft a poll that might be thorough enough. Lots of very clever folks on this forum.
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crossfire

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A friend of, one got his yesterday hes like you parts laying all over.
 
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RobertH3

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I want, want, want but no place to store the completed model. Hanging in the living room would be great but I am sure it isn't an option. :rolleyes:
 

Wally Ferrer

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I want, want, want but no place to store the completed model. Hanging in the living room would be great but I am sure it isn't an option. :rolleyes:
As much as I would love that, I have to agree. Transport and storage dictate it will need to come apart in the middle. Which the makes me wonder if rermoveable rivets will be strong enough or would I need to use screws.
 

Wally Ferrer

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I wouldn’t even know where to begin with recovery for that bird.
I have plenty of ideas, but I like simplicity. Parachute in the front pod, motor ejection would be ideal in my mind. I'm just not sure yet what it would take to clear 10 feet of 54mm tube. I need to find the ejection charge calculator and do some cypherin'... Ultimately I think I'll have to use a bay in the coupler with electronics to blow the nose cone. Using the av bay to attach the main would allow easy replacement of recovery gear, but I worry about the strength and reliability of plastic rivets holding that beast together- I just lack experience to know if it's 'no problem' or if I should think about steel screws instead.
 

Handeman

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It looks like you could do a standard DD setup with the av-bay above the point where the rods attach. Finding the right drogue for this might be problematic. You want a big enough drogue to ensure the two halves don't touch on the way down. That would mean a larger drogue so the fin can hangs pretty much straight down rather than the standard V since those large fins could easily make the fin can "fly". With that large of drogue, you may get quite a bit of drift, but should still be better than popping the main at apogee.

You will definitely have to "fly the field" with this one.
 

Wally Ferrer

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It looks like you could do a standard DD setup with the av-bay above the point where the rods attach. Finding the right drogue for this might be problematic. You want a big enough drogue to ensure the two halves don't touch on the way down. That would mean a larger drogue so the fin can hangs pretty much straight down rather than the standard V since those large fins could easily make the fin can "fly". With that large of drogue, you may get quite a bit of drift, but should still be better than popping the main at apogee.

You will definitely have to "fly the field" with this one.
I am considering this, but I'm unsure of where/how to attach the shock cord/recovery harness. I haven't done minimum diameter motors yet, so I have either used an eye bolt or epoxied the cord, kevlar or nylon to the outside of the motor tube with a slot in the centering ring the cord goes through. I guess I can pick a spot somewhere above the location of the longest motor I would use and epoxy the end of the cord there, but that just feels wrong- can't replace it, hard to get to, etc. I have no experience with minimum diameter motor retainer, but that might be the best choice for the tether attachment. But that solution I think provides for one motor length only, and I don't know what the best length might be. I'm not very likely to fly this to 10,000 feet, but it might be cool to have the option eventually. I should weigh the parts today to get a ballpark figure of what I'm dealing with ;)
 

PatD

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I know someone has a 54mm version of something like this one (38mm from labratrocketry)
1595783862899.png

I just can't find it right now. Install it to accomodate the longest motor and use threaded rod to fit shorter motors. Of course you need to use a plugged fwd closure.
Edit: From the looks of it you might be able to fit a regular retainer in the aft end of it. Dry fit it and see what you have for room. Connect the shock cord to an eyebolt in a plugged end closure.
 
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Wally Ferrer

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I know someone has a 54mm version of something like this one (38mm from labratrocketry)View attachment 425974
I just can't find it right now. Install it to accomodate the longest motor and use threaded rod to fit shorter motors. Of course you need to use a plugged fwd closure.
I take it that hole is for a screw, so it gets screws through the tube wall to install it? Or do you epoxy it in place? Either or?
 

Wally Ferrer

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Edit: From the looks of it you might be able to fit a regular retainer in the aft end of it. Dry fit it and see what you have for room. Connect the shock cord to an eyebolt in a plugged end closure.
I was originally planning to use a standard aft retainer, and since I haven't yet ever used a motor with a plugged forward closure, I wasn't thinking about it as a potential anchor point for the recovery tether. In my mind that would put a lot of stress on the aft of the motor case, but as I think about it, it is probably considerably less than the kick in the pants the motor thrust itself imparts... 🤔 :goodjob:
 

crossfire

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Useing forward closure for shock anchor is done all the time with no issues. AT wouldn't make a thread clouser if it was a problem.
 

Wally Ferrer

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Useing forward closure for shock anchor is done all the time with no issues. AT wouldn't make a thread clouser if it was a problem.
Sounds reasonable, I was only thinking about it as a minimum diameter anchor for the motor instead of a tether anchor. But that is why I started this thread, I need to learn about more options than my limited experience and imagination might come up with. With that as one solution I feel far less blocked from starting the build.
 

Wally Ferrer

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I truly appreciate the replies, I find them all helpful. Now I'm pondering how I would successfully achieve recovery if I keep the body together, and only deploy recovery out of the nose/payload section. I'm assuming nylon or plastic rivets should be strong enough to keep the coupled sections together, and just deploy the main at apogee. If apogee is high enough, use a chute release, perhaps combined with a streamer because as mentioned, those fins could start sailing a bit. There isn't really a whole lot of weight, the length is probably making me overthink this. The hardest part might just be washing the long tube before assembly... :rolleyes:
 

WILDMANRS

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I designed it with dual deployment in mind .the main in the 3” section up top there is plenty of room there ,shock cord attachment normal up top ,below depends on your likes and taste I would glue to apiece of coupler and then glue the coupler in the booster tube.
 
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Wally Ferrer

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I designed it with dual deployment in mind main in the 3” section up top plenty of room there shock cord attachment normal up top ,below depends on your likes and taste I would glue to apiece of coupler and then glue the coupler in the booster tube.
Cool, thanks for that response! It's always good to hear it straight from the rocket scientist's mouth... ;) I've already been doing some preliminary searches for a 54mm av bay...
 

les

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I'm trying to figure out mine as well

Note - the Semroc version has the upper tube overlap the smaller central tube by 2". Based on the 3X scale I allowed 6" of overlap My volume equations are based on this assumption. I have not gone back and figured with Tim's design if that can be reduced or not. If we can reduce the overlap, then the volume grows and my calculation below will require more BP.....

If you want to go for motor eject out the top, you need to consider the total volume of those long tubes.
I did a quick calculation (with some rounding, so probably only accurate to 10~20%).
The motor would need between 3.25 ~ 3.5g of BP for ejection. I'm not certain if commercial motors come with that large a charge. (again, see note above - if less than 6" overlap the volume increases as will the amount of charge required). I doubt this is viable. Tim's DD is probably the way to go.

I'm also a bit concerned with the chute size. My kit weighed 8 pounds, 13 oz, almost 9 pounds. By the time we add the motor retainer, electronics/battery, laundry, motor case, epoxy, paint, vinyl I'm guestimating a recovery weight around 12 ~14 pounds. For about a 15fps landing, a minimum of an 8 foot diameter chute is needed. Descent rate calculator shows at 12# an 8' chute is almost 16 fps. At 14# an 8' chute would be 17.23 fps. To get back to 15.3 fps would require a 9' chute. Even if only 11# an 8' chute recovers at 14.4 fps.

Meanwhile, we have an effective 28" x 3" tube to pack that into, around 170 cu in. (Again assumes we lose 6" of the larger tube (rough total length of ~ 34") to overlap with the smaller tube - we gain space if we need less than 6"). Also, we can store the shock cord in the smaller tube and save all of the volume in the larger tube for the chute. May even be able to stuff part into the nose cone....
 

Wally Ferrer

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I'm trying to figure out mine as well

I'm also a bit concerned with the chute size. My kit weighed 8 pounds, 13 oz, almost 9 pounds. By the time we add the motor retainer, electronics/battery, laundry, motor case, epoxy, paint, vinyl I'm guestimating a recovery weight around 12 ~14 pounds. For about a 15fps landing, a minimum of an 8 foot diameter chute is needed. Descent rate calculator shows at 12# an 8' chute is almost 16 fps. At 14# an 8' chute would be 17.23 fps. To get back to 15.3 fps would require a 9' chute. Even if only 11# an 8' chute recovers at 14.4 fps.

Meanwhile, we have an effective 28" x 3" tube to pack that into, around 170 cu in. (Again assumes we lose 6" of the larger tube (rough total length of ~ 34") to overlap with the smaller tube - we gain space if we need less than 6"). Also, we can store the shock cord in the smaller tube and save all of the volume in the larger tube for the chute. May even be able to stuff part into the nose cone....
Wow, that is great info- you have made way more progress in cypherin' than me- I'm still wrapping up some works in progress but I am now confident I can form a strategy to get a complete build.

The ultra light high-performance chutes from Rocketman indicate a 6' chute might suffice, and it would be loose in all that space... Not inexpensive, but I already have a 60", if I build light enough... 🤔😁

72in. Rocketman Ultra Light High Performance CD 2.2 Parachute
Number of Gores: 12
Weight (oz): 4.6
Packing volume: 2.0”D x 4.875”L=15.318”^3
Decent Rate:
-15fps @ 16.8lb
-17fps @ 21.5lb
-20fps @ 30.4lb
-25fps @ 46.2lb
 

les

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The 2.2 CD is higher than the descent calculator I used, so a smaller chute could work
 

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Hi all! I'm thinking of how I want to go about assembling mine. One question though: The transition from the 3" forward section, to the 2" "main" tube is very loose. Thoughts on attaching this?
 

les

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Another question - thought process
Rail buttons....
With the rings, we can't mount them directly to the 3" tube.

Options -
1) use spacers on the lower large tube to get rail button out past the rings
2) sacrifice one quadrant of rings (cut them away) and use that side for rail buttons
3) mount the buttons to the sail past the rings

In all 3 cases, the issue is the lower tube/sail is not that long (so the buttons will be too close together) and well below the CG/CP. I'm thinking a button will be needed on the upper section or off the smaller tube.

For option 1, use the same spacers on the larger upper tube or even longer spacers on the smaller tube
Option 2 add a button to the larger upper tube directly or a button with spacer if using the smaller tube
Option 3 will require an add on (perhaps to the flange supporting the rods) to mount the button too

Thoughts? Other options?
 

Wally Ferrer

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Another question - thought process
Rail buttons....
With the rings, we can't mount them directly to the 3" tube.

Options -
1) use spacers on the lower large tube to get rail button out past the rings
2) sacrifice one quadrant of rings (cut them away) and use that side for rail buttons
3) mount the buttons to the sail past the rings

In all 3 cases, the issue is the lower tube/sail is not that long (so the buttons will be too close together) and well below the CG/CP. I'm thinking a button will be needed on the upper section or off the smaller tube.

For option 1, use the same spacers on the larger upper tube or even longer spacers on the smaller tube
Option 2 add a button to the larger upper tube directly or a button with spacer if using the smaller tube
Option 3 will require an add on (perhaps to the flange supporting the rods) to mount the button too

Thoughts? Other options?
The lugs attach to the sail right above the rings, and the same distance up from the main tube on the rod support, on the original kit. I figure that's where my rail buttons will go as well, adjusted for rail width. I am slightly concerned about how much room there is to position the upper button on the flange.

IMG_7825.JPGIMG_7826.JPGIMG_7827.JPG
 

les

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The lugs attach to the sail right above the rings, and the same distance up from the main tube on the rod support, on the original kit. I figure that's where my rail buttons will go as well, adjusted for rail width. I am slightly concerned about how much room there is to position the upper button on the flange.

View attachment 426157View attachment 426158View attachment 426159
Math time.... Smaller tube is 2.25", larger tube is 3.125", for a difference of 0.875, divide by 2 = 0.438
The rings are 0.375". Let's allow 0.6" clearance for the 1010 rail (since there is some play and we don't want to be scraping across the rings). So the lower rail button will be 0.975 away from the large tube.
The rod support mounts to the smaller tube, so we lose the 0.438 just to get even with the large tube. The support max is 1.375". Let's get the rail button 0.25" away from the edge, so we have 1.375 - 0.25 = 1.125" - 0.438 = 0.687, which is less than the 0.975, but only by about 0.3". This 0.3" error is separated by about 40" (estimate - have not measured and will depend if you put the button on the top or bottom of the sail)

Even if you take away the 0.1" extra clearance for the 1010 from the rings, it puts the lower button 0.875" from the tube. And if we reduce the 0.25" to 0.1" on the support, that gets us an extra 0.15" or 0.837" - pretty close to parallel (0.018" difference)

So it looks like my Option 3 works with a slight misalignment (without an extension), but probably close enough....
 

Wally Ferrer

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So it looks like my Option 3 works with a slight misalignment (without an extension), but probably close enough....
It does make me wonder if Tim had that, or something else in mind as the clearances are very tight. Also, do fly-away guides have a 1" or bigger stand-off? Might be a possibility...

Edit: Although I imagine the rods would become a liability for fly-away..
 
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