Conway,

Jim has been talking about doing an all-surface mount 10 or 12 bit altimeter with EEPROM memory for the last altitude recorded for at least 2 or 3 years - probably predating the MPac project. The full feature list I'm seeing here is definitely more extensive than what I was expecting, but he was originally planning on going to production in time for LDRS 06 and his paintball electronics business got in the way. I had dibs on 5 or 6 of the way back when he first told me about them, at least as early as May 06 and probably a good bit before then.

I don't care who gets the first ones, I just want enough of them to replace all my RRC2X units - in fact, I started selling off my RRC2X's last summer in anticipation of these coming out. Sold two of them I believe to Troy Hummel and another one to some guy at Oktoberfest. I'm down to only 3 RRC2X's and I hate like hell to swap altimeters between birds.

To be honest, I'd prefer to have other folks fly the first production units so that the bugs get wrung out - I'll take the second production rev of the firmware. I've been in computers far too long to trust V1.0 of anything - no insult to Jim, he does great work, but no piece of code is ever perfect right out of the gate.

Warren

gotcha, accelerometer good, no accelerometer bad. does that put me back to the gwhiz?

I am mostly horrified of accelerometers, and have seen them kill many more rockets than all baro units combined (editorial comment, but based on many observations).

Speaking for me, myself, and I -- Make mine a baro, please...

JW

Wilke started this, so I'd thought I'd jump in...

The new unit is a 10-bit implementation, all SMT (excepting the terminals, electrolytic and piezo) vs. the older 8-bit implementations.

It's intended to replace both the current "classic" and "X" version units. The finshed dimension I'm planning at 1" x 3" (29mm comfy). 9V power basically rules out 24mm BT's.

The unit records the previous flight data to onboard EEPROM. It's retrieveable interactively via pushbutton with LED/Audio feedback. There's no data logging or download/interface capability. The scope of this unit is a replacement to the current product (albeit there's more bells and whistles).

Velocity is just the peak difference in MSL elevation during ascent, snapshot at 1/10th second intervals... not perfect or precise by any means, but is fairly indicative of airspeed.

Time to apogee is from arming elevation (256') to the apogee event, truncated to the nearest second.

I'm using Mick C's absolute pressure standard for calibrating these new units (it's ultra accurate) vs. my older digital manometer.

The firmware borrows heavily from the conventions used in the legacy RRC2 code, albiet I've made significant improvements over that code base. I now maintain dual baro history FIFO's (high speed and low speed trends), the MSL lookup and interpolator is vastly improved, and the main deployment event is using true AGL conversions vs. the old legacy pressure based approximated main deployment... Both test flights last Saturday were flawless BTW.

Now for the best part... it should cost less than the current stuff. I guess I'll have to hold a lottery for the 1st units off the line.

gotcha, accelerometer good, no accelerometer bad. does that put me back to the gwhiz?

I am mostly horrified of accelerometers, and have seen them kill many more rockets than all baro units combined (editorial comment, but based on many observations).

Speaking for me, myself, and I -- Make mine a baro, please...

JW

This debate is one I find extremely interesting...

Baro sensors are truly deterministic, meaning for the bulk of a rocket flight profile (excepting sonic-subsonic transitions) you always know what the rocket is doing (ascending or descending).

Inertial based deployment has it's own set of intrinsic weaknesses despite the continued espousing of the merits of inertial recovery over barometric recovery. Inertial recovery relies on derivation, and there's lots of physical and electrical issues to trip you up... things like:

aliasing
drift
AOA (angle of attack)
compound integral errors

Even my experience with high-end $12000 FOG's in true state-space transformations using inertial-only data makes for some REALLY dismal results. I'm continually refusing position with DGPS data...

For HPR, make main baro too, please....

I wouldn't mind an accelerometer in ADDITION to the baro sensor as long as the baro sensor is the primary trigger for deployment.

Jim,

Would you be considering a more complete suite of features including data download and so forth? Perhaps an RS232 compatible port? I have an RS232 telemetry system good to 7 miles LOS and I'd like to find something reliable to feed it.

Warren

I am mostly horrified of accelerometers, and have seen them kill many more rockets than all baro units combined (editorial comment, but based on many observations).

My observations have been just the opposite. I have seen many more baro based altimeters destroy rockets than acceleration based units. Of course, human error well exceeds both.

I'll never know what cause my latest "technical difficulties" with BDCR but I have no reason to believe that it was the onboard electronics. That unit had been used in at least two dozen flights flawlessly and it gave the required beeps before flight. It is a possibility, but it also possible that it was something else (battery, e-match, etc).

I did use another brand of altimeter and switch to another. Bottom line is for the beginner is identify your requirements, do your own research, pick a brand based on your needs and then see if you like it.

I have my own reasons for preferring acceleration based deployment rather than baro based but that is just my preference.
I am reconsidering my choice for using only one altimeter for my larger projects...

Doug

I guess I'll have to hold a lottery for the 1st units off the line.

Hey Jim- I know you are bizzy so I just went ahead and did the lottery thing and golly gee I seem to have won the grand prize. Thanks! 😉 😉 😉

There are three things: one, we are all subject to our experiences; two, there is a business axiom, if you try to produce a product that is aimed to please everyone, you are doomed to fail, i.e., you can't possibly please everyone; three, remember that MWC is putting this into a much-needed smaller package. It would be impossible to combine EVERYTHING into such a small footprint, even with Moore's law. 😉 Personally, I want two. That's just the size and with the features I need. I have never had a baro failure, nor an accelerometer failure. I don't care which is used. I want a safe deployment. Period.

Conway,

Jim has been talking about doing an all-surface mount 10 or 12 bit altimeter with EEPROM memory for the last altitude recorded for at least 2 or 3 years - probably predating the MPac project. The full feature list I'm seeing here is definitely more extensive than what I was expecting, but he was originally planning on going to production in time for LDRS 06 and his paintball electronics business got in the way. I had dibs on 5 or 6 of the way back when he first told me about them, at least as early as May 06 and probably a good bit before then.

I don't care who gets the first ones, I just want enough of them to replace all my RRC2X units - in fact, I started selling off my RRC2X's last summer in anticipation of these coming out. Sold two of them I believe to Troy Hummel and another one to some guy at Oktoberfest. I'm down to only 3 RRC2X's and I hate like hell to swap altimeters between birds.

To be honest, I'd prefer to have other folks fly the first production units so that the bugs get wrung out - I'll take the second production rev of the firmware. I've been in computers far too long to trust V1.0 of anything - no insult to Jim, he does great work, but no piece of code is ever perfect right out of the gate.

Warren

Warren, Just kiddin and playing around for the most part I really dont care what number I get as long as I have one to fly at and after LDRS...

Also another reason Jim flies Beta production before release. Most Computer related manufactures do not. As its not going to cause your PC to yard dart into someones Mini van... I have NO issues flying any production of Jim's or even Beta testing for him.

I guess I'll have to hold a lottery for the 1st units off the line.

Hey Jim- I know you are bizzy so I just went ahead and did the lottery thing and golly gee I seem to have won the grand prize. Thanks! 😉 😉 😉

Huh you must be hanging out with Warren and smoking whatever he is... 😆

Warren I would not be to fast if I was you to get rid of your RRC2X stuff. That is unless you want to give me one for my Birthday 😆

They are still one of THE most robust and well put together units on the face of the planet. I wont be so fast to part with the one I have. I cant say ive seen to many Altimeters ever survive what Ive heard happen to some of these.

gotcha, accelerometer good, no accelerometer bad. does that put me back to the gwhiz?

I am mostly horrified of accelerometers, and have seen them kill many more rockets than all baro units combined (editorial comment, but based on many observations).

Speaking for me, myself, and I -- Make mine a baro, please...

JW

I wouldnt say I am horrified with Accelerometer units. BUT I do prefer Baro based more as they are far more accurate and seem to get the job done better. BUT what I do like the Accel units for is data collection. I agree with Warren that I to would love to see an Accel on the High end unit like a 100K unit with full logging and down loadable abilities to PC. Kinda guess what I want is more like what the Mpac had to offer. But thats coming from purely a research motor/Rocketeer person.

Also another reason Jim flies Beta production before release. Most Computer related manufactures do not.

Well, there you did it! You let the computer software secret out! Alpha testing is in the lab; beta is for a select few out in the field (or, in this case, prairie). Computer software is, for pretty poor business reasons, let go too soon before thorough beta testing, using customers as the beta test. From knowing Jim a relatively short time--compared to all of you, he doesn't let something go before it's ready. I have no hesitation to grab one of the first off the assembly line.

I cant say ive seen to many Altimeters ever survive what Ive heard happen to some of these.

Okay, okay, so I blew up the booster below my RRC2X, and I mean I BLEW IT UP! Let it go, dude! The real cool thing, although the sound was shaky and quavering, it gave me my correct altitude. Poor little guy...