Altimeters - NARAM60 - MicroPeak?

[vcp]

So before NARAM60, I had zero experience in dealing with altimeters. After NARAM60 I have mostly bad experience. I'd like to try and figure out what I'm doing wrong. I had four flights with normal, very straight boosts to altitude, but three of those reported altitudes in the 30-50 meter range (using two different MicroPeaks). I don't think I was the only one having this problem, as I counted about 20 flights in the results with qualified flights but similar unlikely low altitudes. There may have been more, as there were some reported as 'TL' or not returned. (But I also don't know how many of those were MicroPeaks.)

Along the way, I heard a couple of comments in the nature of: "People are having trouble with MicoPeaks."

I don't have any reason to think that there is a particular failure in the MicroPeak altimeter, but I do think that there is some procedural problem with the way I, and perhaps others, are using it.

The instructions say to turn it on, wait for it to report the prior altitude, then after a delay of one minute for prep time, it will be ready to detect a launch. The problem that I had with this is that after prepping, checking-in, getting pad assignment, setting up the tower and piston; easily thirty minutes could have elapsed. 'De-prepping' the model to recycle the altimeter before launch would have been difficult and wasn't built into the process. Perhaps it should/must be?

Vent holes. Per some threads and comments here I'd assumed that vents wouldn't be necessary. But on a second flight, a vent was added with the same low reading result (utterly certain the altimeter was on). Thoughts on vents re this problem?

Finally, I've heard about a 'light-sensitivity' problem, but no information on the nature of this problem. Does exposure cause low readings/no readings/failure to detect launch/ what? Is light exposure a bad thing before, during, or after a launch?

Anything else I'm missing or should/shouldn't be doing?

TIA.

 

[UhClem]

All pressure sensors, since they are built from silicon strain guages, are light sensitive. If strong light strikes their sensing port it can result in anomalous readings. So long as that port is not in line of sight of the vent holes, you are safe.

The Micropeak records data, have you looked at any data for the suspect flights?

It appears that the only thing recorded is the pressure data and not the internal state. That is important because it uses a Kalman filter. Although with the data and the Kalman gains it should be possible to see what was happening.

 

[BEC]

I worked returns at NARAM. Most of the “track lost” altimeter flights - at least when I was on duty - were MicroPeaks, but not all of them. I don’t know why this was...but we saw them both having not detected launch (still slow single flashes) and some which seemed to have not detected landing (faster single flashes when presented to be read). I knew when I saw one that was not flashing at all that we were in good shape to get some kind of reading, since the MicroPeak turns itself off when it thinks it is done flying.

As to why this was....I don’t know. I’m sure that there are going to be conversations amongst the experts and the maker to see what might be going on.

On static ports: the idea that they aren’t needed is nonsense. All of the altimeters we were using record air pressure and if they can’t sense the air pressure at apogee while the rocket is there, then they are going to give lousy (generally low) readings. Some of them then do the conversion to altitude onboard while others - notably the Adrels - only record pressure and depend on their computer interface program to turn that data into a time vs. altitude graph and data table.

On light: yes, MicroPeaks (and others which don’t have onboard protection including Adrels and early FireFlys) should be protected from bright light. This generally manifests itself as noise in the data but the effects are not - at least for me - predictable.

I flew two Adrels and a MicroPeak in my Classic Model entry (Nova Payloader on a C6-5). All of them were protected from sunlight inside that clear payload section. One Adrel and the MicroPeak were in dark fleece sleeves my wife made and one Adrel was wrapped in blue Quest wadding. The data from all three agreed very nicely (within a meter in max altitude). The Adrel that was in the tissue wrapping rather than cloth pouch had more wiggles in the descent data (the payload section swung around under the ‘chute quite a bit) but it wasn’t severe.

One MicroPeak (and one FireFly) was lost and not returned, though one FireFly did turn up at the lost and found and was there for a couple of days and so far as I know never claimed.

I flew Adrels in my altitude flights and had generally good luck with them. Some did not, but this was more a function of the mishmash of versions of altimeter versions, computer interface hardware versions and computer software versions that are out there....

I really like the MicroPeak and hope that whatever is going on can get sorted out.

 

[vcp]

I should have mentioned that all of my altimeters were not directly, but essentially in the parachute compartment. I'd heard people talk about 'flying naked', with the altimeter just tied in with the parachute, so I thought this would be ok. By 'essentially' I mean that they were in a slot fitted into the shoulder, but open to the parachute compartment.

So re light, they weren't exposed except during prep, and after ejection they were in their shoulder slot, which shouldn't have been direct sunlight. Though I wonder if the plastic was opaque with respect to sunlight. But if sunlight just causes noisy data, would I be concerned about that? Can it trigger a false launch detection?

I guess launch detection is what I'm really wondering about. Did they detect a false launch and record a 'flight', before the flight? Changes in ambient air pressure over time before launch? On venting, they were fully exposed to the pressure at altitude after ejection, I'd have thought it would have recorded apogee then if it hadn't already recorded a 'false' flight.

So being 'in' the parachute compartment, there was the overpressure of the ejection charge, which would be a 'low altitude' spike - would that terminate the flight recording?

Don't have the magic cable, so I can't see the recorded data.

 

[James Duffy]

...after prepping, checking-in, getting pad assignment, setting up the tower and piston; easily thirty minutes could have elapsed

I suspect that this is the problem. Thirty minutes is an awfully long time for an altimeter to bake in the sun, be subjected to gusts, and get jostled about during prep. The flyer's prep procedures should be optimized to minimize the time between altimeter arming and launch, and the NARAM range procedures should be tweaked to help. At a minimum, pad assignment should take place before altimeter issue/check/verification, allowing the flyer an opportunity to get everything at the pad tweaked and ready to go beforehand. That way it would be a simple matter of popping the altimeter into the rocket, sliding the rocket into the tower, engaging the piston, and launching.

I've just returned from flying Scale Altitude at the World Championships, and this flow was almost exactly what was used. We were typically able to go from altimeter issue to launch in less than three to five minutes (note that the Adrel altimeters we used have a three-minute arming delay). Admittedly, we had a dedicated prep and launch area assigned to the US team, but a similar flow could be achieved by simply making pad assignment the first step in the process.

 

[BEC]

Gary - Shoot - I had “the magic box” at NARAM and could have helped you take a look at the data to see what we could learn from the data. Often there is a big spike at ejection - sometimes up, sometimes down - between the pressure change (if the altimeter is exposed to the ejection charge as in your case) and sometimes up or down due to all the shaking that happens - or both. The sensors are also affected by very high G loading. The software tries really hard to filter this stuff out, but it doesn’t always succeed.

As for sunlight and plastic transitions - Apogee has you paint the inside of the transition black in their payload altitude model (the Midge) to mitigate this. I can’t see how sun exposure would trigger a false launch detect (the MicroPeak needs to see a pretty rapid altitude increase to 30m to detect a launch) but I suppose it is possible.

There was some inconsistency in altimeter checkin at NARAM - I didn’t have to show my altimeter was “ready” for any of my four altitude flights. I don’t think that I was using an Adrel was the reason for this. I certainly agree with James that the checkin flow where altimeters are involved needs to take into account the times that altimeters aren’t “watching” for pressure changes - a period which is generally around one minute (PerfectFlite devices, MicroPeak) and defaults to 3 minutes with the Adrel (I have mine set to two minutes). That’s the time when folks should be stuffing altimeters in and buttoning up the rocket. Unfortunately, no altimeter indicates “ready” until after this “I’m not watching” period is over.

Also, if you pop open the compartment that contains the altimeter (especially with your hand over the static vents or if you don’t have any vents) outside this period you can certainly cause a false launch detect.

 

[vcp]

Gary - Shoot - I had “the magic box” at NARAM and could have helped you take a look at the data to see what we could learn from the data. ...

As for sunlight and plastic transitions - Apogee has you paint the inside of the transition black in their payload altitude model (the Midge) to mitigate this. I can’t see how sun exposure would trigger a false launch detect (the MicroPeak needs to see a pretty rapid altitude increase to 30m to detect a launch) but I suppose it is possible.
...

Also, if you pop open the compartment that contains the altimeter (especially with your hand over the static vents or if you don’t have any vents) outside this period you can certainly cause a false launch detect.

Never even occurred to me to ask about a cable or download the data.

Black paint. Got it.

That last is probably the killer. There was a lot of fumbling going on in getting the models set in the tower/piston.

 

[zog139]

Because the amount of time from check in to launch can be a while. What you want to do is check in, get your pad, then right before your model is ready to fly, turn the micro peak off and back on. Make sure it flashes the last flight, then install in your model and fly. I've had good results with this process

YMMV
Jim

 

[BEC]

Jim is quite right, but of course this process only works if your model is set up so that you can do it that way without too much hassle. Another part of integrating altimeters into competition....

 

[mh9162013]

I know this is a necro, but I'm thinking about buying a Micropeak altimeter. I presume the issues discussed in this thread have been addressed and are no longer an issue?

I also assume still no updates on FS Mini or FS Comp availability?

 

[BEC]

The MicroPeak firmware hasn’t been updated in several years and the hardware design has been static I think since it was first released to the public. So far as I know the odd behavior we saw at NARAM-60 (my post #3 above) has not been addressed. But I’ve never personally had any of those issues with MicroPeaks either. I still fly them from time to time and they still work for me reliably.

So —

I would do what Jim Filler suggested, and also make sure it’s not exposed to sunlight while in your model.

Last time I heard from Russ (@gtg738w ) there was no news on the FlightSketch front, or at least no news we wanted to hear.

 

[Gus]

I sold the last few MicroPeaks I had because I absolutely won't waste my time flying them any more. Nothing worse than a great flight with a non-working altimeter. Adrels, Fireflys, FlightSketch altimeters are all way too reliable to waste time on "Maybe-it-will, Maybe-it-won't" MicroPeaks.

 

[mh9162013]

I sold the last few MicroPeaks I had because I absolutely won't waste my time flying them any more. Nothing worse than a great flight with a non-working altimeter. Adrels, Fireflys, FlightSketch altimeters are all way too reliable to waste time on "Maybe-it-will, Maybe-it-won't" MicroPeaks.

Hmmm, good to know...

 

[BEC]

Well…. Steve (@Gus) has a BUNCH more experience flying altimeters where it’s reading determines or helps determine a contest score than I do. So his is a good voice to listen to.

The FireFly is about as simple to use/reliable as you can get. It’s just a tight fit in anything smaller than BT-20. The current Adrels (AKA NCR MaxAlt), while small and relatively pricey (and requiring you to have a Windows 10 computer and a bit of extra hardware to read them) actually work very well. They should, since they are the ones used in international competition.

I’m not as down on the MicroPeak as Steve is, as you can tell from our comments, but his is the voice of competition experience, not mine.

 

[rharshberger]

Well…. Steve (@Gus) has a BUNCH more experience flying altimeters where it’s reading determines or helps determine a contest score than I do. So his is a good voice to listen to.

The FireFly is about as simple to use/reliable as you can get. It’s just a tight fit in anything smaller than BT-20. The current Adrels (AKA NCR MaxAlt), while small and relatively pricey (and requiring you to have a Windows 10 computer and a bit of extra hardware to read them) actually work very well. They should, since they are the ones used in international competition.

I’m not as down on the MicroPeak as Steve is, as you can tell from our comments, but his is the voice of competition experience, not mine.

But your voice is the one that has probably tested more altimeters than anyone else, is there an altimeter you don't own or have tested Bernard?

 

[Gus]

Thanks for the kind words, Bernard! We've seen a huge amount of progress over the few years in micro-altimeters. Realistically almost all of the current altimeters record a flight graph which makes them usable for altitude records. And the reliability of those I mentioned is just wonderful I also really like the Jolly Logic III but it is a bit big for contest flights. What is ironic is that at times the MicroPeaks work OK. The day that Emma set 11 altitude records in a single day she was using MicroPeaks. At the time the Adrels were still a bit glitchy and the MicroPeaks were very quick to download data and recycle to refly. We had a good day with them. But I've had enough no-reads since that I just quit using them at all.

 

[BEC]

But your voice is the one that has probably tested more altimeters than anyone else, is there an altimeter you don't own or have tested Bernard?

I have never owned any altimeter that can do any deployment events. I also have nothing that is older than about 12 years except for one PerfectFlight Alt15K/WD that I got used.

Only a subset of those I have tested/flown are really suitable for LPR contest use from a size/weight standpoint. Of devices you can actually buy today, those are the FireFly, the MicroPeak and the Adrel/NCR Max Alt. If we extend the discussion to ones that we wish we could buy, that list adds the two FlightSketch devices.

Of these, the MicroPeak has the most checkered reputation amongst those who actually have used them in contests. And of these, the FireFly is the only one that cannot be used for NAR records because one cannot download a time vs. altitude history of the the flight (or most of it).

But yeah, I have lots of altimeters and I probably have more flights with one or more altimeters than anyone (save, perhaps, Steve).

 

[mh9162013]

FireFly is about as simple to use/reliable as you can get. It’s just a tight fit in anything smaller than BT-20.

I would like to fit whatever new altimeter I buy in the nose cones of my BT-20 rockets (specifically, the Wizard/Viking and Yankee nose cones, but also the other 2 that are provided in the Estes BT-20 nose cone 4-pack...#3161). I know the FS Mini will fit for sure. I'm 99% sure the Micropeak will fit, based on the dimensions given. But from the online measurements, the FireFly will not.

Do you know if that's the case? My guess is that the Firefly fits inside the BT-20 tubing, but not a BT-20 coupler or Estes plastic nose cone.

 

[BEC]

You are correct. MicroPeak will fit in a BT-20 coupler pretty easily. Firefly will not. Here are some illustrations I just took. I’m on a trip, but I brought some models to fly and one of them is my Checkmate, which uses a BT-20 coupler and a ply disk to form the base of a payload section that’s made from the top 1.75 inches of the main body. So I held a MicroPeak and a FireFly against/in that coupler.

You can also see the black tape that PerfectFlite puts over the pressure sensor on the FireFly to protect it from sunlight and that there’s no such protection on the MicroPeak. So fly it in an opaque or nearly opaque area in the model.

 

[mh9162013]

You are correct. MicroPeak will fit in a BT-20 coupler pretty easily. Firefly will not. Here are some illustrations I just took. I’m on a trip, but I brought some models to fly and one of them is my Checkmate, which uses a BT-20 coupler and a ply disk to form the base of a payload section that’s made from the top 1.75 inches of the main body. So I held a MicroPeak and a FireFly against/in that coupler.View attachment 541353View attachment 541354View attachment 541355

Many, many thanks, BEC!

You confirmed what I was afraid of: the FireFly won't work for my BT-20 purposes.

Now trying to decide if the Micropeak is worth getting or if I should shift my rocket focus to BT-60 rockets instead of BT-20...

 

[BEC]

Many, many thanks, BEC!

You confirmed what I was afraid of: the FireFly won't work for my BT-20 purposes.

Now trying to decide if the Micropeak is worth getting or if I should shift my rocket focus to BT-60 rockets instead of BT-20...

Or, if you already have a Windows 10 computer you can take to the flying field, get an Adrel, a cell to power it and the little USB interface device which doubles as a charger for the cell.

I don’t think either one of us can solve Russ’ supply chain issues so there are more FS Minis and Comps made. I didn’t put a Mini in these pictures because…well, you know why…even though I have some with me as well.

FireFly fits easily in Centuri ST-8 or anything bigger than that. But then so does AltimeterOne/Two/Three and even the Estes Altimeter….not that I would recommend that latter.

 

[PayLoad]

Flightsketch - if you can't actually buy it (and you can't), it simply no longer exists to be compared with anything else.

 

[BEC]

Flightsketch - if you can't actually buy it (and you can't), it simply no longer exists to be compared with anything else.

Ah…I see you fixed your post. I was about to post the link to where the FireFly can be had….

 

[dhbarr]

FlightSketch in a Yankee recorded ~200ft on a c6-7 CATO

 

[mh9162013]

Or, if you already have a Windows 10 computer you can take to the flying field, get an Adrel, a cell to power it and the little USB interface device which doubles as a charger for the cell.

I don’t think either one of us can solve Russ’ supply chain issues so there are more FS Minis and Comps made. I didn’t put a Mini in these pictures because…well, you know why…even though I have some with me as well.

FireFly fits easily in Centuri ST-8 or anything bigger than that. But then so does AltimeterOne/Two/Three and even the Estes Altimeter….not that I would recommend that latter.

I've thought about the Adrel, but I can't justify the asking price for one of those.

I'm wondering if FlightSketch might considering releasing an FS Mini without bluetooth capability. I know that's its big selling point, but an FS Mini that used a blinky light or hooked up to a screen (like the FireFly) is still a vast improvement over what's currently available.

The Adrel is nice, but it's expensive.
The Firefly is nice, but it's too big.
The FS Mini is nice, but it doesn't exist anymore
The Micropeak is nice...when it works.

Oh well, first world problems!

 

[mh9162013]

FlightSketch in a Yankee recorded ~200ft on a c6-7 CATO

I hope the FS Mini was ok!

 

[dhbarr]

I hope the FS Mini was ok!

It was! The Yankee flew again as well.

 

[BEC]

I'm wondering if FlightSketch might considering releasing an FS Mini without bluetooth capability. I know that's its big selling point, but an FS Mini that used a blinky light or hooked up to a screen (like the FireFly) is still a vast improvement over what's currently available.

The bluetooth bits for the Mini aren’t what he can’t get, last I heard. At one point (maybe still) it was the battery holder!

I don’t know what part or parts he can’t get for the Comp.

 

[Gus]

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

 

[BEC]

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 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.

Steve

Right. That was the purpose of taking those images….to show that the FireFly won’t go into a coupler, in response to @mh9162013 ’s query.

You saw the lanyards on both in those pictures. They often get flown outside of dedicated compartments (as do the FS Minis), though if there is room they fly in little pouches my wife sews from scrap fleece material rather than just bare. But that’s for bigger than BT-20 — ST-8 and up.