GPS or RDF

Looking to "upgrade" in the tracking department and having never done any RDF ing I am curious. First priority for me is ease of use. A simple directional arrow or tone would be best. Don't need coordinates,logging,elevation,time,temp,zip code,lunch reccomendations.etc. Just direction to my rocket. Gps units seem to require too much "stuff" and effort to give me info I realistically have no use for and personally find it difficult to link to phones,computers,maps etc. Is RDF as straightforward as it appears? Just rotate an antenna 'till the signal is strongest and move in that direction? If so, I suspect that is what I am looking for. Alternatively, if such a thing is possible with GPS I'd be interested in that also. Anyone have real world experience/advice on what to look for/at? Price is of course a factor, but function and ease of use is most important. Btw, I have no qualms with having to get a technicians license if required.

I only use GPS systems. Never looked to far into RDF with all the newer inexpensive GPS units on the market. Some systems give more info then your looking for. And require you to carry two things around. But the Eggfinder Mini set up is great. Tiny unit in rocket. And one box that gives you an arrow to walk right to your rocket. Also the distance from the rocket.

RDF units are smaller and more mechanically robust. I use them for extreme or space-constrained flights and I have had them survive supersonic shreds. They also have more run time before the battery goes dead, and typically much farther detectable range on the ground, though still much less than in flight.

When GPS works, it is certainly easier and more convenient.

Or both. If GPS loses lock, RDF is fool proof (sort of).

I'm using both & enjoy both. They each have a place for their own. RF definitely has a bit of a learning curve and requires HAM license. Many GPS systems operate on non-HAM bands such as Egg products, Missile Works RTx Navigator & Featherweight GPS. Others such as TeleGPS operates on Ham band. Personally I like the RTx navigator. Walks you right to your rocket without the need of phone or any other device.

cwbullet said:

Or both. If GPS loses lock, RDF is fool proof (sort of).

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Except with RDF if you can't keep a bearing lock at loss of signal, things can get dicey for the recovery especially with a totally sight unseen flight.
If you have to go off at any direction other than the straight line bearing, could lose the line. If you don't get within the ground footprint of the tracker, your rocket can go lost. I've been told it's more important to fly GPS out on the playa as the ground salts cut the ground footprint of an RDF tracker
dramatically. Even walkie talkies don't carry as far. Air propagation is fine but once down it's another story. Fly anyplace else and this doesn't apply.
Those who gained experience when RDF was the only game in town could become very successful at it. If one's rocket can carry both, an RDF backup is good insurance. If the room isn't available it's best to use what you can get away with and make sure the tracker isn't going to crap out with a bad battery or connection during a flight. Plus if going on the playa, best to use a GPS tracker to get you to the last known position. Kurt

ksaves2 said:

I've been told it's more important to fly GPS out on the playa as the ground salts cut the ground footprint of an RDF tracker
dramatically.

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I've flown RDF at Black Rock and Lucerne, and had no particular trouble picking up the signal post-landing, so I suspect this is either a legend or an exaggeration.

It is true that RDF doesn't work very well if the rocket is underground, as is pretty common at Black Rock.

I was going to jump into HAM with the altus metrum products, but then missileworks released the T3 gps and RDF was forgotten. A couple low-risk flights worked out the kinks and it's my favorite thing (even used the last position to find my receiver when I left it where the rocket was picked up.....)

Having RDF backup saved my bacon just last weekend. I've been using both GPS and RDF in my rockets for about 6 years. GPS goes in the nose cone or AV bay and then I'll clip the little radio onto the booster shock cord with the drogue or streamer. Now there's tracking in both ends of the rocket.

Well, one of my GPS transmitters has been a little temperamental since it had a hard landing a while ago, but I decided to use it anyways. Of course, right at launch time it decided to stop transmitting. I went ahead with the flight anyways knowing that I can use the radio transmitter. The Punisher flew to 25k feet and the strong upper winds blew it well over the hills to the south of the range. We got the general direction it was drifting using the receiver while it was in the air, then drove out to base of the hills. We climbed to the top of the first hill and got our bearings with the receiver. We ended up walking about two miles through more sage and over another set of hills but I got my rocket back. I believe in redundant tracking when going high.

There are non-HAM options for RDF. I track using a Marshall Telemetry Scout falconry transmitter in the 218 MHz frequency (one of the unlicensed wildlife frequencies). My receiver is the Com-Spec PR-100A. It's a good combination. Probably the most frustrating part of using RDF is not knowing your distance from the target, although you can guess a little based on the gain setting of your receiver.

If your looking for the easiest to use, most robust GPS with the best range, you cannot beat the Multitronix Telemetry Pro System. “Kate’s” audio tells you where the rocket landed and exactly how far away it is. A simple arrow points you to the rocket and counts down how far away from the rocket you are. The Multitronix unit has a one watt transmitter. That is way more powerful than the other GPS Trackers that I’m aware of. This unit is expensive though.

I also have a Missile Works RTX GPS Tracker. It works. The Bluetooth connection can take a few try’s to connect. The display on the receiver is hard to read in bright sunlight. The RTX is a good unit at its price point.

Older readers might remember the Walston RDF units. I’ve used one of them to locate radio control model sailplanes. They require some expertise and practice to use effectively. I just purchased a Wildman RDF System to use in small 38 mm diameter rockets. I’ll also use the RDF as a backup on high altitude flights if I have to use the Missile Works RTX if the Multitronix unit won’t fit in the rocket.

I have used both the TeleGPS and the Telemini V3 with success. Different devices for different needs.

Ok, since almost everything gps related seems to insist on displaying coordinates, how about recommendations for a SIMPLE hand held gps unit. I DO NOT need or want maps, logging,elevation,battery voltage or anything else that adds complexity/confusion. I had a Garmin don't remember the model# (blue case, e trex?)but it was absolutely unusable. Thought it was me at first but after handing it to several tech savy people, virtually none of them could enter coordinates and get it too simply point to the location. Had a zillion or 2 menus, sub menus, sub sub menus..Does anyone make a hand held unit that will accept coordinates and point to them in basically one step? Or is that just wishful thinking? Think along the lines of the big button cell phone for senior citizens...

An Eggfinder with the LCD receiver and the GPS option will literally point you to your rocket. Follow the arrow and it will take you there... you don't need to mess with the coordinates if you don't want to. You do have to be able to solder, of course, or find somebody who can do it for you...

Missile Works RTx Navigator does the same thing - points you to the rocket!

....and you can pretty much ignore any of the displayed information that you don't want to use.

I have and will continue to use both.
Both have their place - and both have advantages and disadvantages.

Clearly RDF is cheaper, lighter, smaller, less complicated.

Both will get you CLOSE to your rocket.

I'd suggest you choose based on your local conditions and recovery needs:

Is close good enough? Do you need to find that needle in the haystack? - RDF helped me find which sage brush bush hid my NC....GPS gets me to within 50-100 bushes.

Can you recover right away, or do you need hours? RDF has better runtime.

Gentle or hard flight profile? RDF has better durability and is unaffected by the flight profile....I've even seen it used to find lake-stakes.

GPS is great for flights that go out of sight and stand a chance you won't see the main deploy to give you a heading to start your RDF hunt. Once on the ground, both tend to have limited range. So that "last coordinate" before landing that you get from a GPS can be gold.

Lastly, as you get close to finding the rocket, you CAN RDF the GPS packet bursts, but they are harder to use. I keep asking BRB to include a beep along with packets.

I used RDF for 15 years and never lost a rocket. Then at Airfest last year I lost two in unexplainable circumstances. I had a good track on both rockets all the way to the ground. Yet once I lost the signal I was never able to pick it up again, in spite of more than 20 hours over several days of looking. I used descent time and winds aloft to try and make best estimates of how far they should have drifted, talked to other flyers who flew to a similar altitude at the same time of day, used Google earth and a very nice GPS ground mapping system to track my search grid, etc., but no joy.

This year I used the new Featherweight GPS tracker at BALLS on three flights, 14,500', 19,500', and 20,500'. It showed me the heading and distance to the rocket, as well as GPS coordinates. In all three cases the rocket was right where it was supposed to be. I had a good signal all the way down, the farthest one was over 9,000' away. The time to recover was literally the amount of time it took to drive out and get the rocket.

On the other hand I tracked a rocket that landed 4 1/2 miles away at BALLS several years ago with just a RDF tracker. I got the rocket but it took about two hours to find it. Once on the ground at BALLS you typically have to be within at least 2,500' good line of sight to re-aquire an RDF signal. The rocket had landed behind a small hillock and it took a lot of driving before I was able to get a lock on the RDF. The same has been true of all my long distance RDF recoveries, the amount of time it takes to find the rocket that lands a good distance away is appreciable. And that is with 15 years of practice and many flights at BALLS.

With a good GPS system you get a very specific recovery area. With RDF you just get a direction and maybe some idea of distance based on signal strength.

I may still use a RDF beacon in super small rockets that don't allow a GPS unit, but one of my flights this year was a 38mm Mongoose (14,500' on a CTI J150). The Featherweight unit fit easily into the nosecone.

And to your liking, the Featherweight displays a heading and distance if that's what you want. Just keep the arrow green and drive/walk to your rocket.

I know there are other systems that can do much the same thing. My main point is that we might was well take advantage of 21st century technology. It is rocket science after all.


Tony

Fred and Tony,

You Guys did a good job explaining the alternatives. There is no reason that you cannot use both GPS and RDF tracking for redundancy. I’ve been spoiled flying a Multitronix Kate unit. Unfortunately the Kate won’t fit in anything smaller than a 3” airframes nosecone.

This morning I ordered a Featherweight GPS System to fit in my 38 mm Blackhawk. Several forum members have had good luck with it.

Bob you can adjust the contrast on the MissleWorks RTX. Theres an adjusting wheel under the LCD screen. Try that and if you need I'll take a pic and post it. I adjusted mine when I first got it and I see it just fine in direct sunlight.

Bobfly said:

Fred and Tony,

You Guys did a good job explaining the alternatives. There is no reason that you cannot use both GPS and RDF tracking for redundancy. I’ve been spoiled flying a Multitronix Kate unit. Unfortunately the Kate won’t fit in anything smaller than a 3” airframes nosecone.

This morning I ordered a Featherweight GPS System to fit in my 38 mm Blackhawk. Several forum members have had good luck with it.

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I fellow club member has one of the new Featherweight's and I am impressed with that little jewel. Thats my next tracker for sure.

captbk said:

Bob you can adjust the contrast on the MissleWorks RTX. Theres an adjusting wheel under the LCD screen. Try that and if you need I'll take a pic and post it. I adjusted mine when I first got it and I see it just fine in direct sunlight.

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I'ts also recommended to use a 2S 7.2v lipo instead of the 1S with the LCD. It's MUCH brighter and easier to use. A 1S just doesn't have enough to power the RX and the power hungry LCD. This one has been recommended, which is also the same one that the Eggfinder GPS seems to thrive on : https://hobbyking.com/en_us/turnigy-nano-tech-1500mah-2s1p-20-40c-lipo-receiver-pack.html

Tony - GPS is the bomb on the playa.
You can see everything for 100's of feet on the playa.

When you are in knee high (or more) heavy sage like at Brothers or a corn field in Kansas, not so much.
You can walk within 5 feet of your rocket in the sage and miss it.

If you don't get a packet on the ground, you are stuck with the last GPS packet from higher up in the air and some drift will occur.
If you can't see within the landing zone [like you landed in a corn field, or whatever] you'll need to RDF at the end.

When I fly out of sight in the sage at Brothers, I like to have both. A GPS to get me close and the ability to RDF the last 100 yards to get me THERE.

Ok. I’ll throw this out there because of Fred’s statement. Yes when you are in the thick stuff you won’t find a rocket without RDF. Ask the majority of those flying in Wisconsin at Bong Rec and I think they would agree.

I’ll add this to the “finding” topic. If given an option of an external beeper, from now on I’m using it. The only way I found my last flight at Bong was from the faint beep of my Stratologger. I was standing within 10 ft of the rocket. A 7’ DD rocket with 60’ of harnesses. Still could not find it without the audible beep.

By the way, I use BRB products and only had the RDF beacon on board for that flight.

The beeper is a good idea. Too bad that even a loud unit like the Sonic Location Beacon SB20 are muffled when inserted in a nosecone. The corn up in Potter NY in August is up to your shoulders. You could end up stepping on your rocket and still never see it.

I’ve used the Multitronix Kate System for three years now. I have never lost communication with the rocket. My Level 3 Certification Flight landed a mile and a half away in a heavily wooded area. The Kate took me right to the nosecone of the rocket. The rocket landed on a small grass clearing behind the trees.

We've tried beepers and warblers and they can be hard to locate.

One thing that we've kicked around is a strobe that activates at night.
Could be visual or IR with night-vision - then, from a high point, scan the horizon looking for the light.

FredA said:

We've tried beepers and warblers and they can be hard to locate.

One thing that we've kicked around is a strobe that activates at night.
Could be visual or IR with night-vision - then, from a high point, scan the horizon looking for the light.

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Alternating light and sound for a relatively constant power draw is kind of appealing, at least to me.

FredA said:

We've tried beepers and warblers and they can be hard to locate.

One thing that we've kicked around is a strobe that activates at night.
Could be visual or IR with night-vision - then, from a high point, scan the horizon looking for the light.

Click to expand...

Guess my point was RDF can get you really close. Enough to hear a beep. Human ears, at least if you have two of them are about as good of a locator as anything once you’re within that range. A flashing light may have helped me find it too. Good idea.

I used RDF on my first L3 attempt, 25k+. Rocket went up, had signal, then I lost it way before I was expecting to. Drove around our launch site ~15 miles and didn't get signal. Where we fly the soil has properties that make RDF act odd. Some areas attenuate, some reflect.

I came back 4 days later with an amazing friend and ended up hiking 18+ miles and finding the rocket. The rocket landed in a finger of a box end canyon so the RDF was only emitting strong one direction. I got a very, very weak signal up on a high butte at the wide end of the box end canyon approximately 5 miles from the rocket. Epic recovery.

The next launch I used GPS and was at the rocket 30 minutes later and back on the range an hour later. I used RDF as backup. After this flight I switched to exclusively GPS and quickly recovered my rocket, and knew the direction it was drifting in. I'm sold on GPS because of my experience with it. We fly in an area that has gentle rolling hills, but also some high buttes and canyons. It hasn't ever failed me.

Edward

Wallace said:

Gps units seem to require too much "stuff" and effort

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RDF needs stuff as well...and the stuff is bigger in size to carry around. You need a dedicated receiver or a fancy Kenwood or BingBong (whatever it is called) radio. In your other hand you may have a big Yagi antenna. Effort is needed to study for and take the HAM test at a certain place and time. Effort is needed to practice RDF tracking technique, which seems harder than reading lat/long or following an arrow.

At first, I just wanted to "find my rocket, and nothing more", but I now enjoy all the additional data and stuff that can be done with GPS. The GPS products keep getting better/innovative. As mentioned, I also like to work in the 21st century rather than waving an antenna around like Marlin Perkins.

Buckeye said:

RDF needs stuff as well...and the stuff is bigger in size to carry around. You need a dedicated receiver or a fancy Kenwood or BingBong (whatever it is called) radio. In your other hand you may have a big Yagi antenna. Effort is needed to study for and take the HAM test at a certain place and time. Effort is needed to practice RDF tracking technique, which seems harder than reading lat/long or following an arrow.

At first, I just wanted to "find my rocket, and nothing more", but I now enjoy all the additional data and stuff that can be done with GPS. The GPS products keep getting better/innovative. As mentioned, I also like to work in the 21st century rather than waving an antenna around like Marlin Perkins.

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Com Spec is much simpler than you make it out to be. You have a TX and a hand held RX. Nothing more. Do some research.