Metallic paint and trackers

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EXPjawa

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I am building a 54mm, single-deploy MAC Performance Radial Flyer, with a nose bay kit installed in the cone. My intent is be able to place a tracker in the cone, however, I do not yet have any sort of tracker hardware. I thought I read somewhere to avoid metal or metal structures in the nose, due to interference with a tracker. My question is - how much metal does it take to be a problem? Is it just something like a length of all-thread, or would I have problems even if I used a metallic paint on the exterior? This is a consideration now since I'm getting ready to paint. As I said, I don't have the tracker yet, so I haven't finished out the tracker bay (only the bay tube is mounted).
 

timbucktoo

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I have heard the same thing but this past weekend another flyer painted his entire rocket with metal flake paint and stuck an eggfinger in the NC and he tracked his rocket all the way to apogee with no loss of signal.
 

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I have heard the same thing but this past weekend another flyer painted his entire rocket with metal flake paint and stuck an eggfinger in the NC and he tracked his rocket all the way to apogee with no loss of signal.
If it was true metal flake then that would be OK as the flake is actually polyester pieces. Metallic paint contains aluminum flake/powder and this would block/attenuate rf signals. Best to use non metallic paint on the area that the tracker is being contained.

Greg
 

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This is a common question and to date no one on this forum has presented any empirical evidence or analytical data to suggest that the components of model rockets which are metallic, composite, or of other RF attenuating materials hinder the performance of radio devices within the model enough to render the device ineffective within our scope of the use of the devices. Experimentation and bench testing will get you further in this subject than a forum inquiry.
 

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I know that in the eggfinder instructions, it specifically advises against metallic paints near the tracker. Someone with a big open line-of-sight field ought to do some empirical testing, I think that would be interesting information.
 

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This is a common question and to date no one on this forum has presented any empirical evidence or analytical data to suggest that the components of model rockets which are metallic, composite, or of other RF attenuating materials hinder the performance of radio devices within the model enough to render the device ineffective within our scope of the use of the devices. Experimentation and bench testing will get you further in this subject than a forum inquiry.
Not an expert, but like CORZERO I have heard this claim as well, however I can confirm that composite carbon fiber does block radio. Not totally, I did some ground tests using a Comspec AT-2B and it cut the signal down noticeably. When it comes to metal in the airframe I generally try to keep all metals away from the antenna if I can. This is practically because I am somewhat ignorant on the topic so it is a "just in case" approach. However if you read up in HAM forums and antennas it is a common discussion and that is one group that would know. I suspect in some cases metal does have a negative effect but it may go from noticeable to requiring equipment to measure it.

As for metallic paint, rms is correct. I have a couple of cans of the Dupli-color metallic paint after reading these claims years ago I was surprised to find out that it does not contain metallic flakes. However I have heard some painters claim that they use metallic paint with metal flakes. So it sounds like you can't assume on this one and would be better to dig into the specific paint you are using to confirm...that is if you subscribe to the "just in case" approach.
 

Banzai88

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This is a common question and to date no one on this forum has presented any empirical evidence or analytical data to suggest that the components of model rockets which are metallic, composite, or of other RF attenuating materials hinder the performance of radio devices within the model enough to render the device ineffective within our scope of the use of the devices. Experimentation and bench testing will get you further in this subject than a forum inquiry.

This. ALL of this. Especially that last part. My research into paint last year has taught me that very few of today's 'metallic' paints actually contain metal anymore to get the sparkle effect. Nearly all of it is ultra fine cut/ground polyester glitter. This was further solidified when I walked down the block from my office to the two paint/body shops and started talking paint to their folks. MOST of today's paint that's metal flake isn't metal to get around the toxic effects of airborne contaminates along with the solvents. A review of various MSDS sheets will also help to confirm the contents of most paints.

I have several different rockets that have different brands of metal flake/metallic paint on them, and I found that there was NO range difference in ground tests between naked plastic and my painted nose cones. At one point I bought a can of every 'metallic' paint that I could get from testors, rustoleum, krylon and other brands and put my stick antenna eggfinder set up in a test nose cone. I sprayed a smooth, even coat and range tested vs. bare plastic with the nose cone approximately 1 foot off of the ground (on a box) and straight line of sight along the ground for 1.1 miles along the road at Bayboro. WITHOUT stripping paint, I put on the next color and range tested again. Lather, rinse, repeat. At the end of testing, there were like 30 different spray can coats of paint on the nose. NO LOSS OF RANGE.

Conventional wisdom would say that with all those layers, I should have had ZERO reception. Never once broke lock. ALL.DAY.LONG. (and believe me, at the end of the day my wife let me know just how long we had been spraying paint standing in the sun and playing walkie talkie tag).

Not saying that there isn't metal in metallic paint, just that in my 30-odd test samples LAYERED ON TOP OF EACH OTHER, it didn't make a hill of beans difference.

Bottom line.....test your own chosen paint with your electronics. Don't have a test nose cone? Make one out of cardboard.
 

EXPjawa

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Thanks for all the input everyone. I hadn't considered that the paint wouldn't actually have metal in it; that'll be my first thing to check. But with regards to testing to verify, well, as noted in the OP - I don't have any electronics hardware yet to test. That comes into the budget maybe midyear, perhaps before URRF4. But even then, I'm not HAM-approved, so that'll be a limiting factor even then...
 

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My friend tested his Eggfinder TRS for signal degradation, from inside a Estes Mammoth BT which has a metallic surface and same diameter BT plain white. The TRS was on a 1 ft stump. Signal was cut almost in half with the Mammoth BT.
 

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Thanks for all the input everyone. I hadn't considered that the paint wouldn't actually have metal in it; that'll be my first thing to check. But with regards to testing to verify, well, as noted in the OP - I don't have any electronics hardware yet to test. That comes into the budget maybe midyear, perhaps before URRF4. But even then, I'm not HAM-approved, so that'll be a limiting factor even then...
If budget is a limiting factor and you have soldering skills, the Eggfinder has little competition. I spent probably $20-30 on a few practice kits (unneccessary if you know how to solder), $40 on a soldering iron (but could have totally done it with a $15 one), $5 on an LED desk lamp, $8 on a magnifying visor, and probably $15 on LiPo batteries and a charger, and probably another $20 on assorted other bits & pieces. Some of this stuff is stuff that's REALLY handy for rocket building anyway (WHERE HAVE YOU BEEN ALL MY LIFE, MAGNIFYING VISOR?) ... but for about $100 for the kit and $50-100 in supplies, you have a GPS tracker; additional Tx units are $70 a pop.
 

Banzai88

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Thanks for all the input everyone. I hadn't considered that the paint wouldn't actually have metal in it; that'll be my first thing to check. But with regards to testing to verify, well, as noted in the OP - I don't have any electronics hardware yet to test. That comes into the budget maybe midyear, perhaps before URRF4. But even then, I'm not HAM-approved, so that'll be a limiting factor even then...
HAM is not a limiting factor, depending on what you really want to do or for your locator to do for you.

BRB, EggFinder and RTx/GPS are all non-HAM systems of various expense levels. The BRB is very easy to use and what I would call a 'base line' system, the EggFinder is a do-it-yourself assembly kit that's not that hard to do and has great utility, and the MW RTx/GPS is the new gold standard.

If you're working up to a budget, leave the nose cone unpainted until you buy your equipment, test in a test rig, then paint based on those findings. Nothing says that you can't fly with a naked nose cone!
 

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If it was true metal flake then that would be OK as the flake is actually polyester pieces. Metallic paint contains aluminum flake/powder and this would block/attenuate rf signals. Best to use non metallic paint on the area that the tracker is being contained.

Greg
I believe the phenomena is dependent upon the frequency of the tracker and the power output. I had a metallic paint (rattle can Rustoleum) that attenuated
a low powered BeelineGPS riding in the ebay. It was on the 400Mhz/70cm band. Interestingly, I was able to download a valid .kml file so it was able to receive
the GPS signals. Had a 7 to 11 satellite lock. I was lucky the 10k L powered flight came down just within sight. I stripped the metallic paint off the upper bay of a Wildman Jr. rocket, painted it plain yellow and the same tracker exhibits good range.

I've come to the conclusion it's a crapshoot. If one wants to be certain they are not going to have to strip paint or lose a rocket, paint the carrier bay of the tracker
with a non-metallic paint. Or if one's friend successfully flown an X,Y,Z tracker to 20k, use that same tracker and the metallic paint the friend used.

I've been told to avoid black paint in a warm climate as the temp inside can cook off the electronics.

I think Multitronix is the gold standard not Missileworks. Missileworks has a higher power output which helps but a larger footprint than an EggFinder.
Multitronix also has a gold standard price and a larger footprint only amenable to larger projects. Also has 1 watt output in the 33cm band.
Beeline and Missileworks are well known choices for unlicensed trackers and I believe there are a few more but are at a higher price point.

Metal? It's accepted to avoid paralleling all-thread but a metal nosecone tip is fine as it's in the antenna null anyways. A battery on the other side paralleling the antenna
is less than optimal too. Can people get away with less than optimal setups? Sure, but I will tell you it's not pleasant to find out in the middle of the flight that your
range stinks and you have no idea where the rocket went. Kurt
 
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EXPjawa

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I have soldering irons and equipment, but my experience has been in building wiring harness for race cars, auxiliary lighting, etc. Usually that's connecting wires between 10 and 14 gauge together, nothing that involved sitting down at a desk to do fine work or components on boards. Still, its something I can learn. I had seen the BRB, but was still sorting through the pros/cons of that vs Eggfinder, assuming assembly issues are overcome. It isn't that I can't spend the money on one or the other, but more about not wanting to spend more than I have to (balancing that against other things I want spend it on), and knowing what I'm getting for my $$$...
 

ksaves2

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I have soldering irons and equipment, but my experience has been in building wiring harness for race cars, auxiliary lighting, etc. Usually that's connecting wires between 10 and 14 gauge together, nothing that involved sitting down at a desk to do fine work or components on boards. Still, its something I can learn. I had seen the BRB, but was still sorting through the pros/cons of that vs Eggfinder, assuming assembly issues are overcome. It isn't that I can't spend the money on one or the other, but more about not wanting to spend more than I have to (balancing that against other things I want spend it on), and knowing what I'm getting for my $$$...
Rick,

BRB is 250mW output as opposed to 100mW with the EggFinder. You should consider what kind of flights you have planned for the tracker.
At this message one can see the ground footprint of an EggFinder with a patch antenna on a 10 foot pole. It' fairly large: https://www.rocketryforum.com/showthread.php?137555-Eggfinder-Map-tracks&p=1676742#post1676742

Kurt
 

Adrian A

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I have several different rockets that have different brands of metal flake/metallic paint on them, and I found that there was NO range difference in ground tests between naked plastic and my painted nose cones. At one point I bought a can of every 'metallic' paint that I could get from testors, rustoleum, krylon and other brands and put my stick antenna eggfinder set up in a test nose cone. I sprayed a smooth, even coat and range tested vs. bare plastic with the nose cone approximately 1 foot off of the ground (on a box) and straight line of sight along the ground for 1.1 miles along the road at Bayboro. WITHOUT stripping paint, I put on the next color and range tested again. Lather, rinse, repeat. At the end of testing, there were like 30 different spray can coats of paint on the nose. NO LOSS OF RANGE.
I applaud your effort to test it yourself rather than rely on hearsay. A couple follow-up questions, though:
Did the Eggfinder provide signal strength information? Did you have any trouble with the GPS reception? Keeping lock with the tracking radio at 1 mile is probably an easier putt than getting good GPS data, which is a much weaker signal by the time it gets to your tracker.
 

EXPjawa

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Rick,

BRB is 250mW output as opposed to 100mW with the EggFinder. You should consider what kind of flights you have planned for the tracker.
At this message one can see the ground footprint of an EggFinder with a patch antenna on a 10 foot pole. It' fairly large: https://www.rocketryforum.com/showthread.php?137555-Eggfinder-Map-tracks&p=1676742#post1676742

Kurt
Kurt, I appreciate your input. So far, I plan to have flights that go up, come down and are hopefully recovered readily. I don't mean to be flippant, but I'm realizing (I think) that I guess I don't really know what questions I should be asking myself or of the community. The differences that you've pointed out don't tell me anything, because I don't know what impact they have. What I mean is, it isn't something I would've known to compare despite trying to read the BRB user guide (clearly not written for someone at the bottom of the learning curve) or by trying to use this site's excuse for a search function. So, I guess I need to back up to very basic first principles here.

I can tell you this, and maybe that will help frame where you'd steer me next. I'm an L1 flyer. I've not ventured beyond 3-grain 29mm reloads yet, though I've recently purchased a longer 29mm case and, now, a 38mm case to start this season with. I only have one rocket so far that'll take the 38mm case; more are planned later. I hope this season to fly upwards of 4-5000' - so far, I've only tickled about half that. My stuff is single-deploy, and have become adept at using the JLCR to get stuff to drop nearby. But I feel that really anything going over 2000' or so should probably carry a tracker.

All that brings me back around to now I'm starting build with the assumption that I'll have to accommodate a tracker. The Radial Flyer is built with the nose kit, and I'll likely retrofit my 38mm 3" MAC Scorpion with something equivalent. But right now, I hadn't reached any conclusion as to what that tracker would be, only that it should be there at somepoint. Thus, this question about building/finishing the rocket.
 

ksaves2

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Kurt, I appreciate your input. So far, I plan to have flights that go up, come down and are hopefully recovered readily. I don't mean to be flippant, but I'm realizing (I think) that I guess I don't really know what questions I should be asking myself or of the community. The differences that you've pointed out don't tell me anything, because I don't know what impact they have. What I mean is, it isn't something I would've known to compare despite trying to read the BRB user guide (clearly not written for someone at the bottom of the learning curve) or by trying to use this site's excuse for a search function. So, I guess I need to back up to very basic first principles here.

I can tell you this, and maybe that will help frame where you'd steer me next. I'm an L1 flyer. I've not ventured beyond 3-grain 29mm reloads yet, though I've recently purchased a longer 29mm case and, now, a 38mm case to start this season with. I only have one rocket so far that'll take the 38mm case; more are planned later. I hope this season to fly upwards of 4-5000' - so far, I've only tickled about half that. My stuff is single-deploy, and have become adept at using the JLCR to get stuff to drop nearby. But I feel that really anything going over 2000' or so should probably carry a tracker.

All that brings me back around to now I'm starting build with the assumption that I'll have to accommodate a tracker. The Radial Flyer is built with the nose kit, and I'll likely retrofit my 38mm 3" MAC Scorpion with something equivalent. But right now, I hadn't reached any conclusion as to what that tracker would be, only that it should be there at somepoint. Thus, this question about building/finishing the rocket.
No, I didn't take your response negatively at all. All of the GPS systems out there for rocketry are a little bit different and that's what I meant by considering the differences of the
100 mW EggFinder and the 250mW Missileworks. If you're really going to be punching up modest sized rockets really high that have the chance of drifting far, higher power Rf output can be desirous, If you are sticking to 38mm, the Eggfinders and even a TRS can fit and work well. I don't think they'll fit in 29mm but maybe an EggFinder can. Anyone correct me there on that.

Smaller rockets are harder to see at a distance and 38's can really disappear. At 1 to 1.5 miles away under a 36" fluorescent chute there's a good chance one isn't going to see it even if the chute deploys properly.

I've had a good 8 flights with small rockets that really didn't land that far away that I walked right up to and it was obvious the main deployed nicely. Even though my mapping trackers
cued me where to look to get a visual on the main deployment, they weren't seen by me or anyone else under chute, drogue or main. Additionally, I've had a couple of fiberglass rockets that came in with stiff parachutes that didn't fill after being released by the Jolly Logic Chute Release. Didn't see them at all except the EggFinders survived and were giving me positions with the rockets on the ground. That's what is in that message photomap link I posted above. Never saw the rocket coming in but knew exactly where it was at. If I had done that without a tracker, I would have likely been lucky because that was the direction I travel to get back to the main road.

I'd say a tracker is more important if punching smaller rockets above 3000' in windy (> 10mph) conditions. Winds aloft can send them every which way too, not necessarily in the direction of the prevailing ground winds.

Venue plays a part too. If flying at a major launch, people stumble into others downed rockets and return them. I do a lot of flying with few other fliers with
a 15k waiver. I lose it and likely nobody else is going to stumble into it. That's why I'm addicted to the GPS trackers. Fly it, find it fast and can get back fast
to fly the next rocket not dawdling around looking for the last one.

Yeah, once you send small rockets above 2000-3000 feet strange things start happening the longer time they remain out of sight. I'll send up my 38mm motored
ASP WAC Corporal on a 38mm 2 grain H242 but I stuff a 14 second smoke delay in the plugged motor and use a magnetic anomaly detector to deploy the apogee only main chute (with the JLCR) The long smoke gives me as much a chance to maintain a visual but I'll tell you the yellow rocket is hard to see on descent with that restrained chute. I'm lucky if I see a few flashes of sunlight reflected off the paint and it's hard to follow the rocket down. Once the chute is out, it's easier to see.

Other thing I suggest and I do this on all my tracker flights in a newly built rocket is do a first flight that doesn't necessarily spend that much time out of sight so I can shakedown the tracker installation and the rocket. It comes back so I can see it visually and I don't have to worry about losing it on the first flight.
I then start punching with harder motors once my confidence goes up with a given configuration.

Early on I had a deployment failure with a 70cm Ham BeelineGPS and that $259.00 loss was hard to swallow. Farmer found the remains and I got the motor casing back 18 months later at least. The altimeter survived surprisingly but the BLGPS was pulverized to bits.

One other thing is with an unfortunate "sight unseen" ballistic flight, a GPS tracker can lead you to the remains or the hole in the ground. Once the rocket is in the death dive, you just need "one" position. The lower the better. You go to that position and the hole or the fincan sticking up will be nearby. Had one of those too.
If using an RDF tracker, one is likely not going to be able to hold a steady bearing once the tracker is dead as is likely going to happen with a ballistic descent and
crash. Kurt
 

cerving

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The deal with metal near the antenna (including metallic flakes, REAL metallic flakes not plastic lookalikes) is that they scatter the radio waves in a direction that is very difficult to predict. This is not an Eggfinder "problem", this is a characteristic of ALL radio waves around ALL metals to one degree or another. It doesn't matter if it's a 100mW Eggfinder or a 1W Multitronix, it's gonna happen. That's why we tell customers to avoid placing the antenna near metal... you can't predict what it's gonna do. Maybe it won't do much. Maybe your range will go to pot. You just don't know, at least until you try it. In reality, if you're doing a L1 type of flight that chances are that it's going to be OK, unless you're flying a minimum-diameter full-I. I HAVE flown Eggfinders in the AV bay with two allthreads, and kept lock throught the flight, but I wouldn't do that with anything that's going to disappear. If you lose the signal and it's out of sight, it's too late.
 

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Any significant metallic items near the antenna affect the radiation pattern from the antenna. Metallic paints could absorb the rf, dissipating the energy, via eddy currents, to heat.

I have access to a wonderful EMC chamber and equipment. I should set up some experiments one day if I can get time to scratch.

The only problem with this sort of testing is it will be indicative of my specific setup. Lessons can be learned but they won't translate directly to any other build, paints or other materials.

I will put it on my list of things to get to unfortunately.

You could take the empirical approach and measure the range before and after application of paint, using identical setups.
 

Banzai88

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I applaud your effort to test it yourself rather than rely on hearsay. A couple follow-up questions, though:
Did the Eggfinder provide signal strength information? Did you have any trouble with the GPS reception? Keeping lock with the tracking radio at 1 mile is probably an easier putt than getting good GPS data, which is a much weaker signal by the time it gets to your tracker.
Thanks. Mostly, I just wanted to confirm or refute the 'metallic paint' boogey man for myself. All thread or carbon nose cones are a different animal

No, eggfinder does not provide signal strength, although it does give HDOP. I got GPS coordinates throughout, with never more than a second or two between updates. Just to play with it a little, after each paint coat was applied, I turned off the TX until the paint dried a little and then turned it back on, and ALSO moved from one side of the road to the other kinda randomly. Always good lock on and good GPS coordinates, and movement updated right away. Overall, for what I'm doing (L1 and for getting into L2 altitude flights), the eggfinder fits well within my expected usage parameters.
 

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I hope this season to fly upwards of 4-5000' - so far, I've only tickled about half that. My stuff is single-deploy, and have become adept at using the JLCR to get stuff to drop nearby. But I feel that really anything going over 2000' or so should probably carry a tracker.
I fly 4" diameter birds to those altitudes (4-5k) without any tracking routinely. That said, I'm working on my soldering skills so I can build an eggfinder for higher flights with smaller birds.
 

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I appreciate the input. My conclusion of 2000' for tracking is based on my own observations and chasing. I think that a lot depends on when and where you fly; we've got a pretty large site, however, through much of the season it is planted with corn, carrots or beans. A rocket can drop fairly nearby and become obscured in the foliage. Usually, I can get a rocket to drop from 1500-2000' on a JLCR and fall where I can see it and find it readily, but that becomes more challenging the farther they're allowed to drift. And JLCR or not, they drift farther before main deployment even if drogueless when they're coming from farther up. OTOH, I'd imagine that if you are flying over an open desert or something, you'd be able to see it on the ground from a much greater distance...

Most of my mid to high power stuff is in the range of 2.2 - 4". So, they're not real small; my references to 29 and 38mm above were simply the motor choices I moving towards. None of it in minimum diameter, which seems to be impression Kurt had from previous comments. I may build a 38mm powered, 54mm rocket at some point soon, but that would be as close as it comes to that.
 

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Here is the test that someone did on the effects of a black (colored with some form of carbon most likely) filament wound fiberglass nose cone:

https://forum.ausrocketry.com/viewtopic.php?f=32&t=5661

He found a 1db signal loss through the cone. It's worth the read as he explains well how much signal loss really matters...
I've seen a similar post to that effect. The thing to remember there is the tester WASN'T using a carbon fiber nosecone.
The black fiberglass is colored with carbon black to get the black color. It's the carbon black that does the attenuating.

1db is not so bad and if a 900Mhz tracker the figure might be different or perhaps the black fiberglass would have no or little effect at all.

If a long nosecone is used, a higher gain antenna can counteract the effect or as Tim Taylor used to say, "Use more horsepower!!. Argh, argh, argh!"
(In the form of more Rf power.)

For us less sophisticated, doing a range test with the tracker out in the open and contained can yield valid results. If using a nosecone. Walk away and note the distance the signal is
no longer decoded. Take the tracker out of the carrier and walk in the same direction. If you notice you can go farther out, you can make a judgement as to whether or not you can
live with it.

Kurt

Kurt
 

ksaves2

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I appreciate the input. My conclusion of 2000' for tracking is based on my own observations and chasing. I think that a lot depends on when and where you fly; we've got a pretty large site, however, through much of the season it is planted with corn, carrots or beans. A rocket can drop fairly nearby and become obscured in the foliage. Usually, I can get a rocket to drop from 1500-2000' on a JLCR and fall where I can see it and find it readily, but that becomes more challenging the farther they're allowed to drift. And JLCR or not, they drift farther before main deployment even if drogueless when they're coming from farther up. OTOH, I'd imagine that if you are flying over an open desert or something, you'd be able to see it on the ground from a much greater distance...

Most of my mid to high power stuff is in the range of 2.2 - 4". So, they're not real small; my references to 29 and 38mm above were simply the motor choices I moving towards. None of it in minimum diameter, which seems to be impression Kurt had from previous comments. I may build a 38mm powered, 54mm rocket at some point soon, but that would be as close as it comes to that.
In the case of the rocket falling in corn or foilage, try and see if you can fit a beeper on the harness too. The tracker can get you close but I tell you, your ears can do a bang up job
if the rocket is densely hidden. Get within earshot and you have it made.

Bottom line Rick is small rockets up high don't have to drift far to get lost. One simply can't see them on the way down. They don't have to be minimum diameter.

Larger diameter and longer rockets are easier to visually see at altitude. Kurt
 

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Oh, I have a beeper. Or screamer, whatever. But that's only effective if it happens to land such that it isn't muffled. BUT, if a tracker can get you close enough to be able to listen for it, then we're on the right track...
 

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