I was able to use a new RTx system last weekend at OROC's Summer Skies Launch in Brothers, OR. I ordered a new Navigator system with two rocket transmitter units (one wire whip and one RP-SMA), the bluetooth module and the case. I already had an LCD screen, so I just built that into this system. Here are my thoughts on the system and it's performance.
The Units all look very well built. They are a little larger than the old 900 MHz GPS units I built three years ago (
Rocket Track), but I was still able to mount one to a small fiberglass sled with a 1S battery strapped to the back side and fit it into the nose cone of my 38mm MadCow Mini Screech.
So, no problem with size there. This is my smallest dual deploy rocket so this makes me happy.The Screech does have a deep nose cone so if you're thinking of stuffing this into a 38mm rocket, check that you have room to fit a 30mm x 120mm rectangle into the space.
The 3D printed case had a few fit issues that I relayed back to Jim and all subsequent units shipped after this one have been adjusted and should fit the base units perfectly. Another change I made to the case is I drilled a small hole over the bluetooth module LED so I could tell when it has a lock (flashing vs solid).
In my emails with Jim he mentioned that future cases may get some form of clear bezel over this light (I'm not making any promises for him). The hole works fine for me
Power for all my units is this battery:
https://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=44082
From Friday through Sunday last week I flew the RTx system 7 times at Summer Skies. There were six flights with my wire whip antenna unit and one with the RP-SMA antenna unit. I used this antenna from Sparkfun:
https://www.sparkfun.com/products/9143
This is the same antenna I used on my previous system; although I understand that Jim has a very nice flexible antenna in his store.
Since I have the Navigator System and bluetooth, I used this opportunity to track my rockets with both the LCD screen and the Rocket Track app that I was using before written by Kevin Ruland (you can find a link to it in the Rocket Track thread referenced above). I really like the way this app shows your rocket location and tracks you to it. It is open source (I think) if anyone would like to keep making improvements to it. I tracked with the handheld base and my wyfe, the expert tracker, used the phone app (it's her phone and she's been doing it for three years now - no need to stir things up)
Once powered up, it takes a couple minutes for the rocket units to get GPS lock. Once a lock is established there is an audible notification from the base and you can see the appropriate coordinates on the base unit LCD. The base unit also transmits flawlessly and simultaneously to the phone app.
During flights, I experienced some connection loss between the transmitters and the base when the rocket reached apogee and was directly overhead - the connection re-established on descent. This mostly happened on flights over 6-7k AGL. Some of the issue with signal loss might be due to my nosecone design: all my larger fiberglass nosecones have 1/4" all-thread running down from the tip to secure the coupler cover. This runs parallel to the transmitter antennas. I'm going to modify a few of my nosecones to remove the all-thread and see how that improves overhead performance (I know it's a bad design for my nosecones if I'm putting antennas in there).
I also lost signal on most flights after the rocket lands. This is expected, especially with the rolling terrain.
BUT....the base unit remembers the final position of the rocket and where it landed and I never had any issues walking directly to any of my rockets. Also, as you approach the final resting place of the rocket it will reacquire the transmitter signal.
I had perfect concordance between the phone app and where the base unit was directing me to go.
The true test of this unit was realized with the flight of my Mongoose 54 on a CTI L1030 RL. Projected to fly just over 20k feet AGL, we lost visual after apogee and even with three spotters we never saw it land. The RTx system allowed me to walk right to the rocket where it landed about 4300 feet from the pad. You just go the directions that the base unit arrows point. I'm sold!
:handshake:
The rocket units record the flights and you can download them later through the mDACS software. The data can then be exported as KML files (for Google Earth), CSV, or simple text. Here are three of my flights mapped in Google Earth:
Green: 2.6" DX3 to ~3800 ft
Orange: Competitor 3 to ~13,100 ft
Red: Mongoose 54 to ~20,000 ft
I really like the system. It works as advertised.
I'm really looking forward to using the RTx system some more. It was pretty easy to set up and use. In most cases, I just wrapped the transmitter unit and battery in bubble wrap and shoved them into the rocket's nosecone. I'll create some better options for future flying, but it doesn't get much simpler than this. I also plan to test out tethering it to an RRC3 unit soon.
I think my only wish at this point is for a mute button for the audio notifications from the base. When you're out tromping through the field for 30-45 minutes, or sitting at the bench with the unit running, it would be nice to silence it for a spell. You can turn these sounds off through the mDACS software, but it would be nice to have a temporary mute. In talking to Jim it doesn't sound like this is possible on this version. One can hope.
One more note: When connecting the base unit to the mDACS software via bluetooth (which is the best way to do it if you have the unit securely housed in the case), the HC-06 BT module creates two COM ports on the computer when paired: one incoming and one outgoing. Connect mDACS to the outgoing COM port - on my computer it was the higher numbered port.
-brant
