Altimeters - NARAM60 - MicroPeak?

[mh9162013]

A final thought. I rarely fly altimeters in a payload or altimeter compartement. I routinely fly them simply tied with a piece of kevlar to the nosecone. If you have enough wadding to prevent chute or streamer melting, the altimeter will be just fine.

I try to fly my rockets with a baffle + wadding. Yet I still like housing them in a payload bay.

But if it's choosing between the FireFly attached to the nose cone and the MicroPeak in a payload bay, I might need to consider the former option. I just hating wasting all that space in the nose cone while providing plenty of protection for the altimeter.

 

[mh9162013]

Bernard,

Of interest about the Firefly is that it WILL fit in an 18mm tube, but not in an 18mm coupler or nosecone, because of the shoulder. Our FAI Russian friends use Fireflys in their national altitude contests because they work well and are far less expensive than Adrels. No flight tracing, but affordable. Can't be used in actual Cup contests but great for practice. FAI altitude contests require a sustainer at least 18mm in diameter. Almost all use a unibody with rear ejection. Altimeters are activated, slid into the nose, then the motor mount/recovery section is slid in behind,

A final thought. I rarely fly altimeters in a payload or altimeter compartment. I routinely fly them simply tied with a piece of kevlar to the nosecone. If you have enough wadding to prevent chute or streamer melting, the altimeter will be just fine.

Steve
View attachment 541388

Love that rocket. Do you have any more information about it? Links, dimensions, etc.?

 

[mh9162013]

Small update to my altimeter adventures...

I finally got around to using the MicroPeak. So far, I've used it in 4 launches:

Launch 1: Estes Viking (52.4m); attached and placed inside the nose cone
Launch 2: Estes Viking (55.4m); attached and placed inside the nose cone
Launch 3: Estes Patriot (12.7m); attached to kevlar cord in payload bay
Launch 4: Estes Viking (46.7m); attached and placed inside the nose cone

A few notes about the above data. Launch 4 was a little low due to a partially detached fin and my F.A.L.L. not falling away from the Viking until ejection. Launch 2 went fine, but the MicroPeak malfunctioned, as the JL AltimeterTwo in the nose cone read an altitude of 253 feet (the Patriot weighs 120+ grams without an engine or parachute). It's possible (although not likely) that JL altimeter malfunctioned, but this would be the first time that I'm aware of. Also, the Estes Patriot definitely got above 100 feet.

So it looks like my MicroPeak works great in a BT-20 rocket when attached to the nose cone, but not when jostled around in a BT-60 payload bay. What confuses me is why I got the error I did. It's not like I got a bunch of blinky lights or no reading at all. Instead, the MicroPeak starts up and reads: 1 blink, 2 blinks, and 7 blinks. And yes, the payload bay has vent holes (4 of them, actually, and they're 1/16" in diameter. These are the same sized holes I have in my Estes Viking, although just 3 holes are used in that smaller rocket).

I know the MicroPeak has a bad reputation, but my issue doesn't seem related to other peoples' complaints. Just curious as to what I did wrong with the Patriot's launch. Maybe excessive dangling in a super large payload bay instead of being in a small BT-20 nose cone makes a difference?

 

[BEC]

Was the µPeak just hanging from a tether inside the Patriot's payload bay or loose to rattle around or....what was the installation like. All pressure sensors used in these sorts of devices have some sensitivity to shock.

At first I was going to go to the light-sensitivity that the µPeak seems much more susceptible to than others, but it it was inside a close payload bay (and on a Patriot I wouldn't expect that to be clear tubing, then that's not it. (I was reminded of this issue on January 1st when my wife flew one of my µPeaks in her Eggstravaganza-18 (egg lofter from ASP) and we got nonsense readings afterward. In that model the altimeter rides under the egg/foam protector in a clear plastic egg capsule.

 

[mh9162013]

Was the µPeak just hanging from a tether inside the Patriot's payload bay

This, but it was able to rattle around.

I know this is how many people install their altimeters, but it's usually encased in soft cloth/foam/padding in a main body tube or payload bay that's not that much larger than the altimeter itself. In my case, imagine the MicroPeak dangling from the bottom of the Patriot's nose cone in a payload bay the size of the yellow portion of the main body tube.

I wondered if it rattling and jangling around a large payload bay might be responsible, but I though I'd get a different type of error.

 

[BEC]

I AM surprised that it read ridiculously low. I can only surmise that the nature of the randomness of the data caused the filter to select a value much lower than the actual apogee. This is what we saw with the Eggstravaganza last Sunday. When I downloaded the data it was clear that the model had gone higher than the µPeak reported (and that's what our eyes told us as well), but there was so much noise in the data the "correct" value got filtered out.

Just fill the compartment loosely with wadding next time — enough to keep the altimeter from bouncing around — and see if that will help.

 

[mh9162013]

Just fill the compartment loosely with wadding next time — enough to keep the altimeter from bouncing around — and see if that will help.

I'll try that, thanks!