When to get Telemetry

Howdy,

I was wondering when does one start to integrate telemetry? I'm planning a 3 inch, 54mm build that will go 12,000 ft. I would rather wait on the telemetry for now and get GPS, but I want to make sure it's not a safety concern. Thanks!

Go for it a cheap option would be the new Eggfinder. for $90 as a package you aren't getting another GPS for cheaper. You will most definitely want a tracker for a rocket going 12,000ft even if you are using dual deployment which you probably are

What do you mean by Safety concern????

Wow Eggfinder is sweet! I was concerned about safety since the rocket might go out of sight and I didn't want it to lawn dart without me knowing that the drouge or main deploy. I have seen people launch without telemetry/gps or it failed and it was just a guess if we were going to get a lawn dart next to us. Kind of scary. :y:

There is a "velocity" reading that you can use with the mapsphere software . I don't know how accurate it is but I guess you could tell that your rocket isn't coming in at 100mph.

You should get into telemetry just before you lose your first rocket. I did it the other way around and it's not as much fun.

grouch said:

You should get into telemetry just before you lose your first rocket. I did it the other way around and it's not as much fun.

Click to expand...

Post of the day definately.

s6

Actually, I should add you should get the telemetry (or tracking) in operation just before you lose a rocket. My sad tale is that I had a transmitter, but not a directional antenna sitting at home when I lost my last rocket.

At the end of the day, I don't know if you can get cheaper than the Eggfinder. Big Red Bee had the distinction with their transmitter, but unless you have a well stocked ham radio junk box, you would be hard pressed to save much money that route now.

Great post and completely true.

grouch said:

You should get into telemetry just before you lose your first rocket. I did it the other way around and it's not as much fun.

Click to expand...

I use telemetry or tracking about every high power flight. I call it insurance.

In theory, you should launch in a direction that a ballistic return will land safely away from crowds or buildings. Telemetry may be able to tell you a rocket is returning ballistic, but not likely to be useful in playing dodgeball with it.

Telem and tracking are great for finding rockets, but I'm not really sure that they're part of a safety package. I could be wrong, and if I am correct me. I've just always tried to point things away in case of failure, as even if you know where it is, it'd be coming in too fast to do much about it. Of course even if you try to be safe crap happens...

From your explanation of what you want, I am assuming you mean telemetry that transmits the rocket data to the ground in real time during flight, not a tracking transmitter. You want altimeter data and any other data you can feed through the transmitter.

The only real time telemetry I've ever seen fly has been for payloads such as CanSats and for GPS tracking units. The GPS units tend to lose lock during the assent and pick it up near apogee. I'm not sure they would really tell you what you want to know, which is if the rocket is in a ballistic return. I tend to agree with DizWolf. The best practice is to make sure any rocket returning ballistic isn't going to return in the parking/prep areas.

To answer your question, I don't think you really need telemetry at any altitude. It's cool and interesting, but I don't see it as needed. A method of tracking the rocket, either GPS or a DF transmitter, that would depend on your launch site, wind conditions, and what altitude you expect. Where we launch at BattlePark, I use a tracker on most flights over 3,000 ft to speed up recovery more than guaranteeing recovery.

Killachrome said:

Howdy,

I was wondering when does one start to integrate telemetry? I'm planning a 3 inch, 54mm build that will go 12,000 ft. I would rather wait on the telemetry for now and get GPS, but I want to make sure it's not a safety concern. Thanks!

Click to expand...

If you are going "outta sight" it's mandatory if you expect to find the rocket again. Of course, if you only fly at major launches where people are running all over the range recovering
their own rockets, you increase your chances they'll find your lost ship. I've had several disappearing modrocs found in that manner using stupid "power" motors. But, I didn't have much invested in them
if they weren't returned.

That said, a GPS tracking solution is the "stupid man's" recovery method. I'm a lazy "stupid man" myself and like everything to be automatic. The EggFinder is a nice simple unit although one has to build it.
It'll take a fine tipped soldering iron, good light and magnification. If one has an Android phone with a GPS receiver in it or an Android wifi terminal device like a Nexus 7 Flo they'll have most of the receiving station they can use with the EggFinder. Stick GPS Rocket Locator in the Android device, https://play.google.com/store/apps/details?id=com.frankdev.rocketlocator and you'll be able to track graphically.
You just need to get a $6.00 bluetooth board to solder to the labelled pads on the EggFinder receiver, add a battery pack and you'll be good to go.
Look at this thread here: https://www.rocketryforum.com/showthread.php?62624-The-Eggfinder-A-Low-Cost-GPS-RF-Tracking-System
The non-directional beacons are also serviceable but a commercially available set will cost more than the EF. It's an art form.
APRS, a Ham Radio protocol, will take a ham radio license and a lot of ingenuity to get it to work economically.

Unless you want to record a flight, try to avoid having to depend on a laptop as a primary tracker. You want something portable you can carry to the recovery site. Sure, some folks use the laptop to
allow input of the last known coordinates into a handheld mapping GPS, but if they carry the EggFinder receiver with them, they can get a new fix to the final resting place. This wouldn't
be so important if the rocket is fairly close by (say a mile or two) but if it's at a distance, the last received packet may be a fair distance away from the final resting place. Get in close to the
last known position and one stands a chance to pick up a new fix. Kurt

Pictures: EggFinder receiver various shots. "Glare box" painted flat black to make Nexus 7 screen more visible in sunlight.

I recommend one get a matte screen protector like this for their device so it also cuts down glare in the sunlight.
https://www.techarmor.com/tech-armo...001b2166becc&gclid=CKDbsO7D674CFYk7MgodJi4AiQ