Micro Egglofter Enigma

Not sure of the logistics, particularly on something so small, but could you use a standard grade of tissue paper forming a diaphragm of some sort and use a BB or similar as the 'puncture' device? I would think tissue paper is pretty consistent and the BB weight would be as well.

I looked for a few other ideas, but haven't really gotten very far. The other thought was some sort of thin film component (like a resistor) without the protective covering. Sounds like a stretch to me, though.

Good luck.

Sandy.

One of the biggest challenges that I can see with 1/8A is something that Jim Flis alluded to - getting decent hang time using a parachute or streamer. Actually, I have never gotten a 'chute to successfully deploy and fill from a micro model. I realize that payload duration is already in the book for 1/8A, but perhaps this aspect should be more emphasized in the discussion.

In thinking about the whole issue, though, I am reminded that the egg in the egglofting events is supposed to be a stand-in for a biological payload. The idea is to send the "passenger" on a suborbital flight and return it back to Earth unharmed. A standard large hen's egg happens to be about the size of a hamster and has a similar degree of fragility. Back in the early days, people used to do horrible things like launching their pet hamsters in their model rockets, which almost always had a bad result for the creature. Egglofting redirected that curiosity by providing an acceptable substitute. But at the scale of Micromaxx, what biological analogues are there? Most creatures that are this size are invertebrates, and all of them can likely survive a 1/8A flight just fine. Nature doesn't produce items that have the same characteristics as a hen's egg at that scale. (Birds' eggs are small enough, but they have comparatively stronger shells. Besides, as John mentioned right off the bat, their eggs are hard to find or else are very expensive.) That's because nature doesn't generally produce creatures at that scale that are as comparatively fragile as a hamster. Hence the dilemma. I'm all for expanding the number of 1/8A events, and I would welcome some equivalent of egglofting, but finding the right "passenger" is tough.

MK

I think its easy to lift payloads with 1/8A, but trying to get the same "fragility" just isn't going to work. Strength doesn't scale linearly with size; anyone trying to build an HPR out of cardstock will discover that quite quickly. Likewise, trying to build an MMX rocket using the techniques and materials for a large rocket will also fail.

When we're talking about tiny payloads, the force of the impact becomes negligible. There are extremely few things that weigh a few grams but can't be dropped 50 ft onto soft ground without breaking -- there just isn't enough force in the impact. So what are you trying to measure?

lordhedgie said:

I think its easy to lift payloads with 1/8A, but trying to get the same "fragility" just isn't going to work. Strength doesn't scale linearly with size; anyone trying to build an HPR out of cardstock will discover that quite quickly. Likewise, trying to build an MMX rocket using the techniques and materials for a large rocket will also fail.

When we're talking about tiny payloads, the force of the impact becomes negligible. There are extremely few things that weigh a few grams but can't be dropped 50 ft onto soft ground without breaking -- there just isn't enough force in the impact. So what are you trying to measure?

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Exactly my point in one of my previous posts.

Oh, and BTW, I actually have built a high power rocket out of cardstock. More about it here.

MK

I beg your pardon, but that kind of thinking would never have got us to the moon. There is a solution, it just hasn't been thought of yet.

Doggonewild said:

I beg your pardon, but that kind of thinking would never have got us to the moon. There is a solution, it just hasn't been thought of yet.

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I'll Second that Doggonewild!

Lordhedgie apparently you haven't been around Micros much because everything that is being done with or in model rocketry is being done with micros Including many of the same materials, methods and techniques. To be sure we have and are developing alternatives to some things but standard wall .013" craftpaper body, tubes balsa and plastic construction are just as at home in 1.4g micros as Standard and larger models.

Mark is also correct about cardstock or superlight weight HPR model building as well, a little engineering trumps wall thickness just about anytime. The Atlas main body (tanks) are 20ga (about .040") Stainless steel not even self-supporting but this launch vehicle is in it's 40 something year and still evolving. Many folks have built HUGE Mod-Rocs out of cardstock or cardstock and paper but this is WAY of topic.

We are not trying to measure anything, simply find a Micro size fragile payload to bring the NAR eggloft event to 1/8A-A motor models. With time and more searching we'll find something or a combination of somethings that will fill the bill. To be a little more blunt; Button quail eggs are PERFECT for the application but are not easily available for contest use in quantities. NATURE has therefore offered a suitable alternative just not in the quantities or local "easy access" needed "Can't NEVER could". After all landing impact is NOT the only load consideration in egglofting.

The search continues.

You're absolutely right, I haven't been around Micros long. I am impressed with your cardstock HPR rocket, although according to the link you posted it's never actually been flown on an HPR engine (acknowledging your post is over a year old, so maybe you have by now), and it also contains at a minimum basswood fins and epoxy -- not typical construction for a Micro. My point is simply that upscaling or downscaling changes the performance of various materials and techniques, and adaptation is necessary. I doubt you'll disagree with that.

As far as the negative thinking stopping us from getting to the moon, I almost agree. The problem is I didn't say it was too hard, I'm saying its too easy. It's not that you can't design a payload for such a contest, but it won't differ from a standard payload contest because no design considerations will be required to protect the payload.

You'll looking for a payload that will break in a hard landing. Thus, it has to be fragile; meaning it breaks when presented with a given force. The force of impact is a function of mass. With these extremely light masses, very little force is produced at impact -- one of the reasons why weaker materials can be used in construction. In order to break with such weak forces, your payload will need to be extremely weak. Manufacturing and transporting something that weak will be difficult, but getting it consistently the same weakness will be extremely difficult.

For a mental experiment, imagine dropping a glass onto concrete. It will shatter, right? Now one by one pick up the pieces and drop them. If any break at all, it will only be the largest pieces that do. The smaller pieces will survive a drop out of an airplane, because they haven't got enough mass to break.

As I said before, try dropping various 5 gram items a few feet onto grass and see what breaks. When you find something, then you've got a starting point.

lordhedgie said:

You're absolutely right, I haven't been around Micros long. I am impressed with your cardstock HPR rocket, although according to the link you posted it's never actually been flown on an HPR engine (acknowledging your post is over a year old, so maybe you have by now), and it also contains at a minimum basswood fins and epoxy -- not typical construction for a Micro.

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It hasn't flown yet because I don't have HPR certification. I have used epoxy when I have built micros; the instructions in my A.S.P. Micro Sandhawk recommended using it to adhere the styrene fins to the body tube. It calls for just a tiny bit, though; but then, they are tiny fins. Also, if you don't think that solid basswood fins are typical for a micro rocket, then you haven't built any of the FlisKits Micromaxx kits.

The problem with bird eggs is that they are not produced on an industrial scale and sold nationwide, as is the case with hen's eggs.

I wonder about using something with Jell-O. I have an inkling that it could be used somehow, but I haven't thought it through yet. How does the idea sound of using Jell-O in some way as a payload mass?

MK

To magnify the weight, instead of a marble, maybe a 4 gram pyramid inside of something (Jello?), or maybe a pin or nail inside of a balloon of some kind.

(I posted this previously to the wrong thread)

What about a blown eggshell?

They weigh 5 to 6 grams, and are pretty easy to produce. Would not want to make them for a NARAM, but cheap, easy and fairly fragile.

Ok, this might work as well. I can't stop thinking about this, please help me Get a small glass Christmas ornament, you know, those glass balls. Take the metal hanger thing off, and put a lead pyramid, or better yet, like a four-sided die from D&D inside that would fit through the opening. I bet that would break pretty easily. Maybe a small steel rod sharpened on both ends would work instead of the lead, and easier to make. If I had a Christmas ball, I'd be testing this right now.

Don't use anything that will shatter into shards! The idea behind egg loft is to use something that is an analogue to a biological payload. The aspect of fragility is important, but it is not the sole issue. Using a glass ornament (yikes!) or an empty egg shell with a hunk of metal inside takes one quite a long distance away from the original concept of an egg lofting event. How is either one analogous to a living "astronaut?"

I definately see your point, and agree with you on using things that might be dangerous. I have broken those ornaments, and they don't break into sharp shards. If they did, they wouldn't be putting them on Christmas trees for millions of kids to possibly break. It wouldn't be a large metal object, it couldn't be to fit through the hole in the ornament. But the point to the whole simulation is to duplicate the fragility of a biological payload, without using one. This is made harder with the fact that it must be able to be launched with MMX engines. We could have everyone go raid robin nests for their eggs, but that just wouldn't be right. This may or may not work, I'm just throwing ideas out there to solve a problem.

One more thought, a sphere is strong against pressure from the outside only, so something inside might break it quite easily if it bounces around a bit. It might not need anything pointy. I'm hoping someone has the balls to test it out.

Doggonewild said:

I definately see your point, and agree with you on using things that might be dangerous. I have broken those ornaments, and they don't break into sharp shards. If they did, they wouldn't be putting them on Christmas trees for millions of kids to possibly break. It wouldn't be a large metal object, it couldn't be to fit through the hole in the ornament. But the point to the whole simulation is to duplicate the fragility of a biological payload, without using one. This is made harder with the fact that it must be able to be launched with MMX engines. We could have everyone go raid robin nests for their eggs, but that just wouldn't be right. This may or may not work, I'm just throwing ideas out there to solve a problem.

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Robins Eggs are TOO Big!!! We are looking for something 5/8" in dia or perferably smaller. Somewhere around 5grams or less. Glass just isn't going to make the grade, sorry but we really need to continue the search for something fragile without the broken sharp edges.

Some sort of very thin membrane or fine tissue might be possible with an internal splitting mass. Are their super tiny thin wall balloons? Some type of tiny Hollow very thin wall float? Some sort of liquid filled (Non-glass) ampule or vial?

Have we completely dismissed using an electronic payload?

A simple circuit could be developed to only measure peak acceleration. You would (probably) not need timers or iginiter outputs for upper MMX stages, or for apogee sensing and igniter signal for deployment charge, at least not for a pseudo-eggloft contest. Would it be possible to develop a one-function circuit, that fits on a small enough board (3/8 x 1?), holds a button cell, cheap enough for clubs to afford ($10? $15? $20?), simple enough to operate for someone not familiar with bigger, fancier electronic payloads?

Seems like an overlooked opportunity for some vendor to get a foothold into MMX and low-power electronics. Could open a market for a simple, one-function altimeter (I'd buy at least one) tiny enough to fit into these smaller birds. Or an upper stage ignition system based on a simple timer (no accelerometers, etc) Or maybe a deployment timer based on a simple timer and using a Q2G2 igniter to burn a thread (use engine ejection to deploy small recovery system at altitude, use electronics to release bigger system at N seconds into flight, just like the "big" rockets use dual-deploy)

You could drop-test 100 eggs (equipped with accelerometers) to see what the thresh-hold level of "g" is to get a consistent crack, and set that as the same not-to-exceed criteria for a MMX contest roc.

I have no doubt that someone (maybe even a few people) actually are working on genuine DD for Micromaxx. (Seriously, to get around the 0.86 second motor delay.) An accelerometer payload for micro egglofting? Now that's an IDEA!

Very nifty thought Powder. Wonder if Perfectflight or Pico could produce such a device?
Pico has a tiny altimeter for micros and at least 2 Staging timers already.. as always with micros, it's the Darn power supply that get in the way

I had seen the Pico products, and those are certainly great for low power--right on the money, actually.

But I'm still kind of wishing that it was possible to make equivalent gizmos that would fit inside the smaller MMX-sized tubes without having to use a payload section with larger BT diameter. Then again, the electronic components themselves might not even be available in sizes that small. Oh well, I guess you can't have everything.