Any tips for finding rocket in cornfield?

[Rocketcamper123]

That's a cheap shot, and one that is not backed up by any data.
I fly Eggfinder GPS and Misseleworks T3 GPS. Both are 900 Mhz band GPS trackers, both work reliably. The two are virtually interchangeable (you get to solder the first, you buy the other pre-soldered).

You can buy Eggfinders GPS in either 900 Mhz or 70cm / 400Mhz Ham Version.

"seem cheap" is the definition of trash talking.
TRF has a policy of not bashing or denigrating the few vendors we have in the hobby.
Please respect it.

i said nothing wrong with 900mhz. i have 900mhz trackers, ham license trackers, along with rf trackers. all i said i dont trust nor like a particular brand. relax. if I don't like i don't buy. i respect the vendors that make and sell gopd products.

 

[ksaves2]

Ahhhh,

I forgot to mention to use the Sight n’ Go feature with a Yagi RDF antenna one simply holds the Garmin GPS next to and parallel to their Yagi antenna when the signal is peaked. Of course, if one is still able to receive a signal from their RDF tracker once their rocket is down, they’re in the catbird seat. Can easily walk to and increase the attenuation of the incoming signal as they approach their rocket to maintain directionality of the incoming signal. I was amazed by the Comspec stuff in the 2006‘ 7 era as to how close a bearing they could maintain at very close range. Great if ones rocket is in standing corn.

If the rocket is out of ground Rf footprint range, that last bearing is incredibly important so one can walk the line and get within ground footprint range to home in or if using a GPS tracker, get a final fix if the GPS has a good shot to the sky to the satellites.

I haven’t had a problem with a GPS tracker on any frequency in the terminal phases of recovery as they were always sending out a fix of some kind when I reacquired a signal. The accuracy might be off somewhat but here is were a ”sound making” or “screamer” device on the recovery harness is helpful. One’s ears are actually an excellent terminal recovery device if one gets within ”earshot” of the noisemaker! Don’t underestimate it.
I’ve sent up noise makers on modrocs with no Rf trackers and as long as they came in within sight, even though they landed in standing corn, I was able to find them. I had some ruckus two stage modroc flights that disappeared for 2 minutes and then I hear the streamer “flapping in the breeze”. When down low with no time to get a “Sight n’ Go“ fix live, I’d sight and try to get the best Sight n‘ Go fix I could get then started “walking the line”. With a noise maker on the harness, I recovered the rocket every single time even in standing corn or a bean field. Good gosh, sound and one‘s ears are incredibly good in the terminal phases of a recovery!

If the GPS receiving antenna was facing the “dirt” there might not be coordinates transmitted. This is where a tracker that continues sending out an Rf signal is important as technically one could convert to RDF tracking to find the rocket. Some GPS devices stop sending an Rf signal if no positions are received from the satellites. That could technically be a problem for a difficult recovery. As long as a GPS tracker is transmitting an RF carrier, even if it’s sending garbage, one could convert to RDF and find it using the bearing/attenuator method. (As long as one has the equipment.)

A difficult recovery would be a rocket that lands quite a distance away from the receiving station with a loss of signal close to the ground. Altitude or height above ground is absolutely great for signal propagation. It’s when the transmitter gets closer to the ground that things get dicey. With 400Mhz and 144Mhz trackers the propagation is better than the 900Mhz (33cm) stuff. Yagis on 400 and 144 can be used effectively for in-flight tracking of the entire rocket flight. The “beamwidth” of Yagis on those frequencies is broad enough to be able to point the antenna to the “sight unseen” rocket to maintain the telemetry download more easily.

With 900Mhz the beamwidth for inflight tracking might lead to loss of signal as the narrow beam might not be easily positioned with a handheld Yagi antenna. Once the rocket is on the ground and is more than likely fixed, (unless the wind is blowing it away) pointing a Yagi antenna is easier as one knows where to point the antenna. As mentioned, I’ve tested this out with my 900Mhz trackers and a 900Mhz Yagi does effectively increase the ground footprint of a 900Mhz tracker. Get into tracking. It saves one’s rockets. Especially if one has to fly solo or at sparsely attended launches. Best regards,
Kurt Savegnago

 

[mbeels]

I know all that. I might be a biologist by education, but I hung out with e-mag majors in college. My roommate would test my home brewed antennas (I had a thing for quagis at the time) in the RF lab’s anechoic chamber.
So knowing all that - why do rocketeers do RDF by peak seeking? Is it easier? Did nulling fall out of fashion?

I see, reading comprehension failure on my part, I answered the wrong question. I don't know! I don't think I've actually seen anyone doing RDF for tracking rockets, GPS systems seem to be so popular now.

BTW, a few years ago I built a 15 element quagi for 70cm, and then recently a smaller 70 cm antenna. I still remember the guys with the antenna equipment hooking it up to the network analyzer and exclaiming, "Look at the return loss on that thing!" That was fun.

 

[ksaves2]

Ummm, One other thing. In my early days in 2007, Walston was

Kurt, you’ve got a lot of experience with different systems, maybe you can answer something that’s piqued my curiosity about RDF rocket tracking.
In the late 80s-early 90s, I played at 2m fox hunting. Everyone was using phased arrays and null seeking, rather than the peak seeking I see rocket RDFers doing. Do you know why?

Charles, I don’t know why. As I see it, with null seeking with a hand held Yagi and attenuator, one would be holding the Yagi and turning around until they got the null signal. In that case, the transmitter would be behind them. Seems counter-intuitive to me. With the Walston hardware, the local prefect let me take a tracker and the receiver/attenuator home to “play with”. Yeah, I was the one that placed the transmitter out there but I was amazed as to the directionality even when up close with optimizing the attenuator settings. Was pretty darned good. With phased arrays, doesn’t that use multiple antennas which would be hard for one to hand hold carry?
A single optimize Yagi seems to work well enough at least with the Walston/Comspec trackers. I saw a lot of folks doing RDF tracking with Walston/Comspec stuff when I started out in ‘06. I think Comspec had a different name back then but I forgot what it was. Actually the RDF trackers were of higher power back then until the FCC clamped down and dinged them. I still have a transmitter replacement case that is a lot larger than the current transmitters and I believe the earlier trackers put out a lot more power than the current ones.
Umm, in fact I think I have one of the older Comspec transmitters that is actually legal as it’s hard programmed with my ham callsign. I gotta clean out the basement to find it.

Cripes, back in the “old days” it was “technically” illegal to use those trackers to track rockets! When the local prefect ordered a system, he told them it was going to be used to track “his horses” on a “nonexistent“ farm he owned! That is no lie. They were “supposed” to be used as animal trackers for wildlife purposes. Technically we/them rocket people were doing something “illegal” in the FCC eyes back then. The deal is it didn’t bother anybody so the Feds didn’t come after us rocket guys and the Walston/Com-spec people looked the other way as they wanted sell product.

In the early 2000’s, RDF was the only game in town and GPS tracking was only just coming out for beaucoup bucks. The Kenwood D7Ag just went out of production and the Yaesu VX-8R was a piece of doggie do-do as one couldn’t pull the NMEA packets off the thing with a cable to shunt them into a handheld mapping GPS like could be done with the Kenwood product. The KW D72A changed that and I bought one really quick for my Beeline GPS units. Still works nicely to this day with an old Garmin 60 CSx. Kurt

 

[OverTheTop]

I am guessing it is counter-intuitive so it was not even thought about. You also need to have a different antenna. By peak-finding you can use the same yagi that you used for receiving telemetry on the way down. That's just my supposition anyway. The loop antennas have a nice null fore/aft, but yagis have complex lobes and lots of "nulls" but only one major lobe.

 

[Charles_McG]

I am guessing it is counter-intuitive so it was not even thought about. You also need to have a different antenna. By peak-finding you can use the same yagi that you used for receiving telemetry on the way down. That's just my supposition anyway. The loop antennas have a nice null fore/aft, but yagis have complex lobes and lots of "nulls" but only one major lobe.

Don’t they think that the bi-null pattern of a loop is what did in Amelia Earhart? She located on the wrong null and flew -away- from the next stop?

The antenna that was popular with my fox hunting friends was just 2 1/2 wave dipoles spaced a 1/2 wave apart, and tuned by adjusting the spacing. Easy for 2m. Perhaps it was 2 1/4 wave whips. It’s been 30 years. No harder to point than a small yagi. The front lobe was only about 1.5 dB and about 90° wide. The null could be -30-40db and just a couple of degrees wide - if you took the time to tune it.
The Comspec gear is certainly more intuitive to use.

 

[John Kemker]

Re: Peak-seeking vs. Null-finding

Mostly, I think that it's the extra fiddly-bits for null-finding that turns most rocketeers away from it. The phased arrays you're talking about require careful tuning of antennae and feedlines. It's not so bad at 144MHz or even 440MHz, but a real pain at shorter wavelengths, such as 900MHz. Even a millimetre off on one of the feedlines can mess up the whole array.

 

[Tim Crabtree]

If you are working near the maximum range of an amplitude-based system then finding the null is like trying to find the peak when you are too close - both the null and the peak will be somewhat broad in those situations.

In a phase based system, like Marco Polo, the receiver is in saturation all the time so, disregarding the effects of noise, the system works the same from a mile away or an inch away (literally). This is why a Pseudo Doppler RDF will lead you right up to the transmitter with no manual peaking, nulling or attenuation required at the receiver. The disadvantage is that Doppler systems operate with an array of omnidirectional antennas, which only have a peak gain of about 2 dBi. A directional antenna may have a peak gain of 8, 10 or more dBi. This gives the directional antenna system a greater maximum range. Now, plowing through the cornfield while sweeping a 12-element Yagi back and forth, you have to imagine that one for yourself.

 

[ksaves2]

I know all that. I might be a biologist by education, but I hung out with e-mag majors in college. My roommate would test my home brewed antennas (I had a thing for quagis at the time) in the RF lab’s anechoic chamber.
So knowing all that - why do rocketeers do RDF by peak seeking? Is it easier? Did nulling fall out of fashion?

I think it's psychologically easier to point a Yagi in the direction where one has to go and with a sensitive meter, know that's the way to go. Yeah, I know a Yagi has some side lobes but if one has an idea where the rocket is, pointing the major lobe with the receiving antenna is not too hard to do. The Walston/Com-Spec stuff I had a chance to play with was pretty good even close in with the provided attenuators. I have a Marvin White attenuator that works really nice on 2 meters (144Mhz) and 70cm (400Mhz) bands. Kurt Savegnago

 

[djs]

Charles, I don’t know why. As I see it, with null seeking with a hand held Yagi and attenuator, one would be holding the Yagi and turning around until they got the null signal. In that case, the transmitter would be behind them. Seems counter-intuitive to me.

I did this once when a rocket ended up in a pond at Bong. Kept getting weird directional info from the receiver. I think the transmissions were doing strange things with the tracker underwater- bouncing around or whatever. With null seeking, I was able to zero in on where it was, until I saw the floating nose cone.

 

[PayLoad]

..... the few vendors we have in the hobby.
Please respect it.

......Spits coffee all over the monitor....

 

[ksaves2]

I did this once when a rocket ended up in a pond at Bong. Kept getting weird directional info from the receiver. I think the transmissions were doing strange things with the tracker underwater- bouncing around or whatever. With null seeking, I was able to zero in on where it was, until I saw the floating nose cone.

I’ll keep that trick in mind thank you! Probably an ultimate way to track would be to use a GPS tracker on the rocket and send out a “trained” drone for a photo reconnaissance mission. Spot the chute or rocket in the corn and get a final fix from the drone. Easy peasy recovery then. Kurt

 

[BABAR]

Not sure if anyone got the easy answer.


Fly the rocket after the corn is harvested

 

[Tim Crabtree]

We have had many customers recover drones and rockets in cornfields using the Marco Polo recovery system. Because the Marco Polo handheld locator is very small, less than 3 1/2 inches wide, you can walk through the rows of corn while holding it and, because it is a pseudo Doppler direction finder, it operates literally within inches of the tag transceiver- taking you directly to the rocket. You will step on it if you are not careful.

https://eurekaproducts.com/rc-model-tracking-and-recovery/

 

[Tim Crabtree]

Check out this video of a guy recovering a small drone hidden in tall grass:

 

[afadeev]

We have had many customers recover drones and rockets in cornfields using the Marco Polo recovery system.

You may not realize this, but the vast majority of drones have their own GPS receivers (one in the drone and another in the controller), making this device (and the weight penalty that comes with it) totally and completely redundant.

Are you a vendor for this gizmo ?

 

[HHaase]

Any update from the OP if he ever found the missing rocket?

-Hans

 

[Tim Crabtree]

You may not realize this, but the vast majority of drones have their own GPS receivers (one in the drone and another in the controller), making this device (and the weight penalty that comes with it) totally and completely redundant.

Are you a vendor for this gizmo ?

Yes, I am the vendor and we have been selling these systems for over 8 years to many thousands of drone users, model rocket enthusiasts and pet owners.

Totally AND completely? Wow, that is really redundant!

The 12 grams of weight is not really a factor for any but the very smallest drones. Please take a look at at the video I posted where the drone crashed in the tall grass. It is doubtful that he would have found it using relative GPS coordinates. Here is another one:

 

[billdz]

Any update from the OP if he ever found the missing rocket?

-Hans

No, it is still missing.

 

[Ronz Rocketz]

I have an idea. Dont fly a rocket into a corn field. If you point a rocket towards a corn field then you have wasted a perfectly good rocket.

Now if during recovery it floats into a corn field then just wait until the combine goes over the field. You will find rocket but it will be in pieces.

Just having a laugh. I have landed in a corn field before but it came in ballistic. I found it in pieces.

That’s like saying don’t shoot the target frame at the rifle range but sometimes my AK says, nope not today.

 

[BSNW]

All I can tell you is that yesterday my Marco Polo paid for itself TWICE in one day. Please see the photos below. If anyone here knows the farm field where we launch at in Muncie Indiana, they would know it is very big and rolling.

Everyone was landing in the corn or soybeans. I did as well. My flight in the photos below was from a flight that landed very far away. I would have NEVER found this rocket without this tracker. It is very simple, cost effective and works right out of the box. Also, at a NOTRA launch last month, It saved/found no less than 4 rockets in corn and soy as I loaned it out and used it myself.

Say what you will.....But while the rest of you are walking rows and flying drones etc., the folks with Marco Polo's are simply walking up to our rockets and flying again. I have tested it and it works. I personally know 4 other rocket fliers who got one after using or seeing mine. I have put mine in a model rocket all the way up to a 7' 5.5" diameter high power....IMO it is the greatest bang for your buck. I cant believe I ever launched without one. In the lower photo, notice the arrow pointing to the cone on my hand held....I wonder where I put the tag/transmitter in this rocket? Hmm......

 

[Big-Bob]

I have considered a drone, but good ones are super expensive and just not in my budget. I have lost a few cheap rockets over the past 5 decades, but last year I lost a $150 rocket. Plus all the work I put into it. I changed to a different launch site. I have had a few rockets come down in tall mesquite bushes (I usually launch in the AZ desert) I found them, but it was not easy to get them down. I have used a 2 piece 20' long 1/2" PVC pipe with a string and hook on the end of it, and believe it or not, I have reeled in a couple of them with a fishing pole.

I had never heard of an Estes Trajector before (I don't typically use kits) but after checking it out, it does not appear to be a cheap rocket. Around $75, and uses E and F engines. Designed to reach 2000+ feet. Or is there another cheaper version of it?

 

[afadeev]

Drone to the rescue pictures set #2.

Background - I finally went Club launching rockets again yesterday, 9/12.
Got to fly everything I've built over the spring, and summer (10+ kits), then starting working my way through winter backlog of builds, including 3" diameter 4-foot long Estes Smoke (#9704, I think). Last flight of the day, everyone is watching, plenty of eye balls for tracking. Upgraded to 38mm MMT, it took off on a G67R motor, and promptly weather cocked into a wind gust. Rocket sim-ed to be going 73.1 ft/s off the rod, but reality wins every time, so off it went at ~30% angle.

Not a problem, wind will bring it back once the chute opens at projected 2,000-foot apogee, right?
No, not this time. I was expecting a straight up flight, and set the JL CR to release at 300 feet to minimize the walk.
We all observed the separation near apogee, chute comes out held in place by JL CR, opens at 300 feet a good 1,000+ feet East from the launch pad. Rocket lands gracefully, everyone agrees "no problem, it's in the field in front of the abandoned green houses".
I go to the projected landing area, NO bueno.
Sun is getting lower, I'm tired, Android 11 broke my DJI fly app so I can't use the drone. Drove home, dug up an old iPhone, planned to go back to look for the rocket on Sunday.

Today, I returned to fly the drone over the projected landing area - nothing.
A few trash bags and farming debris here and there, but no rocket.
Then I flew the line of sight from the launch pad towards the landing area landmarks (house and a utility pole), and at exactly 2,000 feet from the launch pad, in waist to chest-high weeds, I saw this (DJI says picture was taken from 15.4 meters, or ~50 feet):


I kept the drone hovering over the spot as I hiked towards the area on foot.
The heights of the weeds and reeds varied from 3" to 6", and the area where the rocket landed was nicely hidden from view by taller weeds around it.
Stumbled over a grown deer hiding in the weeds along the way (saw it from the drone, figured it would run away by then, but it didn't). My puppy went after it, I was concerned I will never see the dog again and won't know where to look for it, but it caught up with me before I got to the rocket.
This is what the landing site looked like from the ground, from five (5) feet away:


This is me and my 3-month old puppy extracting the rocket:


As per usual, the rocket was way further than the eye-balls had estimated.
It was a bit behind the abandoned green houses (picture above is facing North, launch site is ~2,000 feet to the left/West), in the wide field of overgrown weeds. Even though it was painted bright and contrasting white / red, I could not see it from ten feet away. And it wasn't in the general area I would have searched on foot!

There is no way I would have found the landing spot without drone's view from above.
$300+ of hardware recovered (JL CR, 38mm RMS motor, chute, rocket, etc).

 

[Ronz Rocketz]

So the deer took the rocket away from where you expected it, obviously.

 

[OverTheTop]

Oh deer...

 

[Banzai88]

Since I purchased a MW RTX, I've encountered the law of trackers.....that anytime you use a tracker, your rocket will easily land within visual range.....but JUST ONE TIME that you launch without it, and it's lost!

Seriously, though, the navigator set RTX has sent me right to the thing, every single time.

I made a pod for a tracker out of a piece of orange coupler that hooks onto the recovery harness so that everyone that wants to use it, can. Since then I've found many a rocket that were otherwise hidden in the beans/corn, including two that were not spotted by drones.

 

[Spitfire222]

I know this isn't strictly on-topic, but since there's discussion of drones in this thread, I just thought I'd share something fun. Yesterday morning, I lost my Estes Alpha on the roof of the middle school where I launch. This afternoon, I returned with my DJI Mavic Mini, under-slung with a weighted hook on some fishing line. It took a few minutes to locate the rocket, and a few more minutes to hook a shroud line, but eventually I got it down. This is rocket #2 to be saved by my drone! (My Citation Patriot owes it's second chance to this Mavic as well).