Eggfinder TRS / LCD to 17,000 Ft?

[kevinkal]

I'm planning to fly a project to 17K this weekend at XPRS/Blackrock, using my Eggfinder TRS that has the stock wire antenna for 900 Mhz transmission. For receivers, I'll be using both an Eggfinder LCD and an Eggfinder Rx connected to my laptop, both with the upgraded antenna that Chris sells using an SMA connector. I've had good results to 7,300 ft thus far with no significant missed data packets until it's on the ground.

For those with experience using Eggfinders and their range capabilities, what are your thoughts on the range capability for this setup? How high have you flown with what antenna setup?

I spoke with Chris at Dairy Aire this year, and he mentioned getting data from 5 miles out using, if I remember correctly, a similar antenna setup on his Eggfinder.

 

[rc dude]

For my L2 I had TRS telemetry all the way to 24k. But this was using a rubbery ducky antenna on both ends, I'm not sure how the wire antenna affects it.

Good luck with the flight!

 

[High Desert Rocketry]

You should have no problem...I've done them over 50,000'

 

[Wayco]

My highest flight was in a carbon fiber Mongoose 75mm minimum diameter rocket flying an M840. The Eggfinder was in a fiberglass nosecone with no all thread near it. It went to 28,905 and was recovered about 3 miles away. Things to consider are the speed of the rocket on ascent and the terrain you are flying in. High g flights usually loose lock on the GPS, but mine always came back before apogee. I have never flown at Black rock, but have been told that the playa sucks up signal. If you regain signal before the rocket lands, you can usually go to the last location recorded and regain it for the exact location of your rocket.
I still think we have not found the max range of the Eggfinder. Good luck on your flight.

 

[kevinkal]

For my L2 I had TRS telemetry all the way to 24k. But this was using a rubbery ducky antenna on both ends, I'm not sure how the wire antenna affects it.

Good luck with the flight!

You should have no problem...I've done them over 50,000'

My highest flight was in a carbon fiber Mongoose 75mm minimum diameter rocket flying an M840. The Eggfinder was in a fiberglass nosecone with no all thread near it. It went to 28,905 and was recovered about 3 miles away. Things to consider are the speed of the rocket on ascent and the terrain you are flying in. High g flights usually loose lock on the GPS, but mine always came back before apogee. I have never flown at Black rock, but have been told that the playa sucks up signal. If you regain signal before the rocket lands, you can usually go to the last location recorded and regain it for the exact location of your rocket.
I still think we have not found the max range of the Eggfinder. Good luck on your flight.

Thanks for the feedback. My confidence is up.

My simulation shows that it will pull 14 g's max acceleration, have a peak velocity of 1520 ft/sec (Mach 1.32) and coast for 24 seconds before Apogee at 17,300 ft. Hopefully I'll get tracking data back during the coast to apogee. The TRS is mounted in a 4" Filament Wound Fiberglass Nosecone with an aluminum tip that uses a steel washer and screw for mounting (standard Madcow tip mount). The antenna is 8" below the aluminum tip, oriented with the longitudinal axis of the rocket pointed at the nosecone tip, which I hope will not impact the monopole antenna RF pattern, given that it's RF pattern is minimized pointing straight off the antenna ends.

As far as the Playa sucking up RF.. I'm guessing it's related to the moisture content in the soil.. which will be up this year given the wet winter and recent rains(yesterday). Hopefully, since the RF is emanating from well above, the range won't suffer much until close to the ground.

 

[OverTheTop]

Nothing ringing alarm bells with your flight or construction. Should work well. Good luck and enjoy!

Personally, I usually blow the main at about 1800' just to give extra time for receiving the final packets before landing, when flying GPS telemetry. I think it just ups the odds a little. YMMV.

 

[ksaves2]

If you are wanting to find the rocket and not so interested in live tracking with saving the data, you should be fine. All you need is one position just before touchdown to get you within the ground footprint
of the tracker. Follow OverTheTop's advice to blow the main as high as you can afford because with the tumbling settled down, you start to get more positions coming in to develop a drift trend.
The ideal position of a tracker antenna is the same as the receiver's position but as you know a rocket under drogue has a tendency to flop around. That does affect the range as the antenna polarity is
changing with the position. Once dangling in a stable descent, the positions start streaming in. If your rocket is higher up, the greater the chance you'll get positions based on line of sight.

This holds true with Ham radio APRS tracking except that the packets are streaming it at once every 5 seconds as opposed to the "possible" 1/sec of the Eggfinders. Even then with the very high fliers that are
way up there and taking their time coming home, missing a packet and having silence for 20 seconds doesn't make much difference as far as the recovery is concerned. Under the slow main descent
you get enough positions to get you to the ground footprint. If you don't see it by then, you'll get a new position to go to. If you got the room, put a beeper on the harness 'cause even with a GPS tracker,
if you are standing nearby you still might not see it due to vegetation. Out on the salt flats/playa you don't have that much of an issue with tall vegetation but the ground footprint of the tracker will
be much less. The dissolved salts suck up Rf like a sponge and the ground range is much less. Mind you, your range in the air is just as good as anyplace else but lying on the salt, it's less than if it
was lying on the ground in farmland.

Make darned certain your mounting is secure because if your antenna gets "smushed", you'll be lucky to receive any positions at all. Have a great flight and wished I was there to track it too! Kurt

 

[OverTheTop]

Don't forget a little bead of epoxy around the GPS antenna base on the Tx. You don't want your GPS antenna falling of the PCB under boost or deployment accelerations.

 

[kevinkal]

Nothing ringing alarm bells with your flight or construction. Should work well. Good luck and enjoy!

Personally, I usually blow the main at about 1800' just to give extra time for receiving the final packets before landing, when flying GPS telemetry. I think it just ups the odds a little. YMMV.

Don't forget a little bead of epoxy around the GPS antenna base on the Tx. You don't want your GPS antenna falling of the PCB under boost or deployment accelerations.

If you are wanting to find the rocket and not so interested in live tracking with saving the data, you should be fine. All you need is one position just before touchdown to get you within the ground footprint
of the tracker. Follow OverTheTop's advice to blow the main as high as you can afford because with the tumbling settled down, you start to get more positions coming in to develop a drift trend.
The ideal position of a tracker antenna is the same as the receiver's position but as you know a rocket under drogue has a tendency to flop around. That does affect the range as the antenna polarity is
changing with the position. Once dangling in a stable descent, the positions start streaming in. If your rocket is higher up, the greater the chance you'll get positions based on line of sight.

This holds true with Ham radio APRS tracking except that the packets are streaming it at once every 5 seconds as opposed to the "possible" 1/sec of the Eggfinders. Even then with the very high fliers that are
way up there and taking their time coming home, missing a packet and having silence for 20 seconds doesn't make much difference as far as the recovery is concerned. Under the slow main descent
you get enough positions to get you to the ground footprint. If you don't see it by then, you'll get a new position to go to. If you got the room, put a beeper on the harness 'cause even with a GPS tracker,
if you are standing nearby you still might not see it due to vegetation. Out on the salt flats/playa you don't have that much of an issue with tall vegetation but the ground footprint of the tracker will
be much less. The dissolved salts suck up Rf like a sponge and the ground range is much less. Mind you, your range in the air is just as good as anyplace else but lying on the salt, it's less than if it
was lying on the ground in farmland.

Make darned certain your mounting is secure because if your antenna gets "smushed", you'll be lucky to receive any positions at all. Have a great flight and wished I was there to track it too! Kurt

Thanks for the feedback and suggestion. I have generally been deploying the main at 700' with a back up deployment charge at 500'. It makes sense to do this higher as you suggest.

I had to stand down on my plans for Blackrock yesterday. I over estimated my ability to complete my Avionics bay in time. At best I would have pulled an all-nighter and left for Blackrock at 3am with no sleep. It's probably for the best, as I have an early flight out off San Jose across the country to Virginia Monday morning, and the drive to Black rock is over 6 hours each way without traffic. Little sleep building day and night, 6 hours of driving early this morning, little sleep tonight out on the playa, then another 6 hour drive home Sunday.. and getting up Monday at 3:30am to catch a flight... I came to my senses and called it off.

Instead, I'll be setting up my avionics today and will configure the altimeters to deploy the main at higher altitude.. I'm thinking 1200' with a 1000' backup. I anticipate the chute will require an additional 150' to open.. thus I'll be under the main for ~1050' to give the Eggfinder TRS time to send data. At 4000' MSL, I anticipate a descent rate under the main of 19 ft/sec. OpenRocket simulates that I'll have 55 seconds of slow fall time under the main for the 1200' deployment compared to just 27 seconds if the main deployed at 700'.

A few months ago, I had some Aeropoxy ES6209 left after bonding some fiberglass parts. I used a little of it to bond the SIRFstarIV GPS antenna on two clean opposing edges for by my Tx and TRS. I used some IPA to clean the surfaces before bonding. I was temped to sand them a little.. but opted no to risk getting sanding debris, which could contain some metal dust, into the Eggfinder components. Hopefully, this will keep the antennas on permanently. I assume the Aeropoxy is a much better bond than the BSI epoxies, and sufficient for this purpose. It worked well since it's very thick, and did not run down the side of the antenna onto the PCB.

My TRS and Tx antennae are simply cantilevered off the end off their PCBs per the stock Eggfinder build directions. They have had no problems with 40 G launch accelerations. I did have one get slightly bent to the side one day, but that was due to multiple side impacts on my nosecone while my rocket was being dragged under a chute that was inflating and pulling the nosecone/tracker up and dropping it repeatedly onto hard dirt... Not fun to watch while trying to catch up to it as it dragged away.

It now looks like I'll be flying this a the TCC October Skies launch next month. I'll have to keep my altitude under the waiver, which I believe is 16K.

 

[RGClark]

My highest flight was in a carbon fiber Mongoose 75mm minimum diameter rocket flying an M840. The Eggfinder was in a fiberglass nosecone with no all thread near it. It went to 28,905 and was recovered about 3 miles away. Things to consider are the speed of the rocket on ascent and the terrain you are flying in. High g flights usually loose lock on the GPS, but mine always came back before apogee. I have never flown at Black rock, but have been told that the playa sucks up signal. If you regain signal before the rocket lands, you can usually go to the last location recorded and regain it for the exact location of your rocket.
I still think we have not found the max range of the Eggfinder. Good luck on your flight.

What's the best mass ratio you were able to get using carbon fiber casing? I'm investigating getting an amateur built orbital rocket using solid motors. It requires lightweighting the motors by using carbon fiber casings.

Bob Clark

 

[ksaves2]

Kevin, since you are flying a TRS you'll have the baro altitude to ponder in real time.

Ummmmm, Bob..... Ahem. You said amateur "orbital" rocket. That's nice to simulate and ponder but where do you expect to fly this thing? Out of your own island in the middle of the ocean? If said project comes down on someone's head, you going to have launch insurance? What makes you think you can pull off
an orbital flight cheaper than Space-X?

I remember at TRA some years ago there was the "Big Idea" that brought a number of people together online (it was by invitation or petition only I believe)
and nothing became of it. Orbital is very difficult to achieve safely on a shoestring budget. If you are very wealthy and can afford it, I
can eat my words. Kurt

 

[kevinkal]

I flew to a little over 13,000' last weekend using a TRS with the stock wire antenna. I had a Windows Laptop "base station" with an Eggfinder Rx feeding Mapsphere data. I also had an Eggfinder LCD with Bluetooth feeding my Android phone running Rocket Locator. The Rx and LCD both had the upgraded SMA mounted monopole antenna that Chris sells. All systems worked perfectly! I lost data during the boost, but regained data right at apogee... and tracked it down to the ground about 1.3 miles away. Data reception did become sparse near the ground, as expected. Here's a 3D plot of the data acquired using Mapsphere on my Laptop Base station:

 

[ksaves2]

When you got to the 1.3 mile last known position were you able to see the rocket being dragged or did you get a new position that told you which way to proceed? Kurt

 

[kevinkal]

I was able to see the bright orange 84" top flight chute was inflating ad swinging up into the air. I was able to see it.. but the LCD was also receiving data and Rocket Locator was updating nicely. I think the fact that the TRS was in the nosecone that was kiting 20 or 30 feet in the air each time the chute inflated helped with RF range, giving me transmission range that I would not have had otherwise. That poor TRS went up and down in that nosecone for about 30 minutes before we could get to it.