Recommend a good accelerometer

[MasonH]

I am in search for a good accelerometer. I do not NEED it to be able to fire an ematch or other pyro, but I do need it to be able to measure and record the flight data accurately. I would LIKE it to have one set of terminals for battery, and another for switch.

That said, anyone have a good recommendation?

 

[Reinhard]

Generic recording accelerometers are not too common, especially ones with a high enough range for rocketry use. I think it would be the easiest solution for you to get an accelerometer based altimeter (Raven, Marsa, Telemetrum, et. al.).

Reinhard

 

[dixontj93060]

How about an AltimeterTwo: https://www.jollylogic.com/products/altimetertwo/

 

[MasonH]

I honestly had not considered that.

 

[Eyeguy41]

Altimeter 2!
Couldn't be easier to use and gives all the data you are looking for and more and can easily move from rocket to rocket.

 

[troj]

If the Altimeter 2 isn't what you're looking for, the only thing that comes to mind off the top of my head is a Telemetrum, but that's way beyond what you're looking for. They're also temporarily unavailable, which I realize also doesn't help you much.

-Kevin

 

[CarVac]

I am in search for a good accelerometer. I do not NEED it to be able to fire an ematch or other pyro, but I do need it to be able to measure and record the flight data accurately. I would LIKE it to have one set of terminals for battery, and another for switch.

That said, anyone have a good recommendation?

Ravens are pretty good for the price, given that they can handle 70g, but they don't have separate battery/switch terminals, and there is some sample variation with respect to accuracy.

I want a digital-accel version without the ADC inconsistencies please, Adrian! I'll buy one as soon as they come out.

 

[jderimig]

Marsa54 has a very linear and accurate accelerometer and separate terminals for battery and switch.

Its cost may be more than you consider, but if this is a scouting endeavor i will offer a generous scouting discount. PM me if interested.

 

[MasonH]

Marsa54 has a very linear and accurate accelerometer and separate terminals for battery and switch.

Its cost may be more than you consider, but if this is a scouting endeavor i will offer a generous scouting discount. PM me if interested.

I am actually looking to use the accelerometer, as well as an altimeter (and backup, as necessary) in a project for my Aerospace engineering/Capstone project for school. Not a scouting endeavor, but a school one.

 

[jderimig]

That counts....

 

[H_Rocket]

Mason

I have two MARSA devices and will gladly work with you. Then if it is what you need, you can chat with John.


Speking of which - John, I can fly the test unit again in mid Sept. PM me if need be.

 

[troj]

Marsa54 has a very linear and accurate accelerometer and separate terminals for battery and switch.

Its cost may be more than you consider, but if this is a scouting endeavor i will offer a generous scouting discount. PM me if interested.

I knew I was forgetting something that was readily available -- and this is it!

-Kevin

 

[MasonH]

Mason

I have two MARSA devices and will gladly work with you. Then if it is what you need, you can chat with John.


Speking of which - John, I can fly the test unit again in mid Sept. PM me if need be.

Think I can have a look see if/when I vacuum bag over there?

 

[BLKKROW]

Hey Mason I will send you an email on facebook about this.

I have a Raven 3 that will not fire ejection charges but may still be good to record. I am testing this with my next rocket.

 

[cerving]

If you're still looking for an altimeter and don't mind putting a kit together, I'll give you a Scout discount on an Eggtimer kit (see www.eggtimerrocketry.com). PM meif you're interested. I have a 16 y/o son that's a Life Scout, he's working on the Eagle... amazing how things slow down once girls/cars/friends get in the way...

I am actually looking to use the accelerometer, as well as an altimeter (and backup, as necessary) in a project for my Aerospace engineering/Capstone project for school. Not a scouting endeavor, but a school one.

 

[Tetrahedron]

I am in search for a good accelerometer. I do not NEED it to be able to fire an ematch or other pyro, but I do need it to be able to measure and record the flight data accurately. I would LIKE it to have one set of terminals for battery, and another for switch.

That said, anyone have a good recommendation?

I have been using Robert DeHate's PICO AA1 and it works well with good accelerometer data from my EX motors:

https://cart.amwprox.com/index.php?...mart_product_id=404&virtuemart_category_id=19

THX, John

 

[r1dermon]

that's hilarious...i was just gonna post

https://www.picoalt.com/ AA1

 

[Jmhepworth]

I have a 16 y/o son that's a Life Scout, he's working on the Eagle... amazing how things slow down once girls/cars/friends get in the way...

I call that the 3 Ps. Pigskin, perfume and petroleum. You hit two of them, but left out sports.

Joe

 

[Larry Curcio]

I am in search for a good accelerometer. I do not NEED it to be able to fire an ematch or other pyro, but I do need it to be able to measure and record the flight data accurately. I would LIKE it to have one set of terminals for battery, and another for switch.

That said, anyone have a good recommendation?

The field of accelerometers has thinned a lot recently. The inexpensive ones that are left are, IMHO, unacceptable. You might try the GWIX HCX. Previous models have yielded excellent data. I haven't tried this particular model, but one is in my future.

https://www.gwiz-partners.com/html/g-wiz_hcx.html

Regards.
LarryC

 

[jderimig]

The field of accelerometers has thinned a lot recently. The inexpensive ones that are left are, IMHO, unacceptable. You might try the GWIX HCX. Previous models have yielded excellent data. I haven't tried this particular model, but one is in my future.

https://www.gwiz-partners.com/html/g-wiz_hcx.html

Regards.
LarryC

Larry,

Are you referring to the specific MEMS chips currently in production or specific altimeters? If the former can you please expand on this and share your data with respect to specific MEMS modules which you feel are unacceptable and on what basis?


Regards
John

 

[cerving]

Well, he does play ice hockey, which is kind of a big deal in SoCal... it's year-round. He's tapering down though... girl(s).

I call that the 3 Ps. Pigskin, perfume and petroleum. You hit two of them, but left out sports.

Joe

 

[cerving]

Don't know what you're trying to say, but high-G accelerometer sensors are definitely more expensive than baro, which is why you don't see them on $100 flight computers. There are a few promising new parts, but they're not readily available yet. Most of the commercial flight computers are based on the Analog Devices ADXL series, it's an analog part which is good and bad; the resolution depends on the ADC that you use, so if your MCU doesn't have sufficient resolution then you have to add an ADC part to the board.

The field of accelerometers has thinned a lot recently. The inexpensive ones that are left are, IMHO, unacceptable. You might try the GWIX HCX. Previous models have yielded excellent data. I haven't tried this particular model, but one is in my future.

https://www.gwiz-partners.com/html/g-wiz_hcx.html

Regards.
LarryC

 

[Larry Curcio]

Larry,

Are you referring to the specific MEMS chips currently in production or specific altimeters? If the former can you please expand on this and share your data with respect to specific MEMS modules which you feel are unacceptable and on what basis?


Regards
John

John,

Actually, I'm not commenting on MEMS chips. In fact, I'm seeing altimeters with components at least as good as older altimeters that yield poorer results. I used to see data like the graph attached. Today, I'm seeing acceleration altitudes on the order of half the barometric altitudes in hot weather (where the barometer should be under-estimating).

The data in the attached are from an ARLISS flight with a GWIZ LCX flight computer.
I would see similar consistencies with the ARTS II. Even though that instrument had issues, it gave useful acceleration data.

Regards,
-Larry

 

[Larry Curcio]

Don't know what you're trying to say, but high-G accelerometer sensors are definitely more expensive than baro, which is why you don't see them on $100 flight computers. There are a few promising new parts, but they're not readily available yet. Most of the commercial flight computers are based on the Analog Devices ADXL series, it's an analog part which is good and bad; the resolution depends on the ADC that you use, so if your MCU doesn't have sufficient resolution then you have to add an ADC part to the board.

Well, I'm not comparing accelerometers to barometric altimeters. I would agree with what you say, and add that it also matters how the parts are put together. (Nothing controversial here.) I'm just not seeing a lot of usable acceleration data lately, and I'm growing depressed over the situation. (See my reply to cerving)

Regards,
-Larry

 

[cerving]

The general rule is that accelerometer data is more accurate than baro when you're going up and/or fast, and baro info is more accurate when you're going slow. Baro data for velocity is really not as good as accel, even with a good filter, because it's not a direct measurment; it's inferred by another event (pressure change) that can be affected by other factors. Acceleration and velocity are directly measured by an accelerometer, so as long as you get rid of the noise it's going to be solid data.

Since most flight computers' primary task is parachute deployment, which occurs when the rocket is going slow (hopefully...), baro-only works just fine. If you want to control something while going up (i.e. an airstart), an accelerometer has the edge. The airstart logic in the Eggtimer has a lot of parameters that you can play with to get it as right as you can get it with baro, but it will never be as good as what you would get with a good high-G MEMS accel chip. Of course, it wouldn't be $40 then, either...

Going back to the original post, I agree with the consensus... the G-Wiz LCX 100G version appears to be the best choice for the money; a Raven 3 with the 70G accel would be fine too if your rocket's performance falls in its range.

 

[jderimig]

Well, I'm not comparing accelerometers to barometric altimeters. I would agree with what you say, and add that it also matters how the parts are put together. (Nothing controversial here.) I'm just not seeing a lot of usable acceleration data lately, and I'm growing depressed over the situation. (See my reply to cerving)

Regards,
-Larry

Larry, no reason to get depressed.

Here is a plot of data from the MARSA54 on Gerald Meux min diameter N5800 flight at LDRS. He posted this data in his video file and was kind enough to share the data with me.

Blue is inertial altitude, red is barometric. Flight to 30K pretty decent integration wouldn't you say? He also used this data to characterize the motor and it estimated the thrust curve and total impulse of the N5800 within 10% of the certification values.

 

[jderimig]

Going back to the original post, I agree with the consensus... the G-Wiz LCX 100G version appears to be the best choice for the money;

What consensus? the LCX wasn't even mentioned until your post.

 

[bobkrech]

Don't know what you're trying to say, but high-G accelerometer sensors are definitely more expensive than baro, which is why you don't see them on $100 flight computers. There are a few promising new parts, but they're not readily available yet. Most of the commercial flight computers are based on the Analog Devices ADXL series, it's an analog part which is good and bad; the resolution depends on the ADC that you use, so if your MCU doesn't have sufficient resolution then you have to add an ADC part to the board.

ADXL375 3-axis 16-bit 200 G digital accelerometer, $5.74 in quantity over 100 available in September.

You don't need an accelerometer for a dual deployment altimeter. Current baro units work fine to 100 kft and use Kalman filters to eliminate Mach delay timers, and cost less than $100. Stick a $5 accelerometer into a $100 altimeter and you get a Raven, or similar altimeter for ~$150.

Bob

 

[4kids49]

ADXL375 3-axis 16-bit 200 G digital accelerometer, $5.74 in quantity over 100 available ub September.

You don't need an accelerometer for a dual deployment altimeter. Current baro units work fine to 100 kft and use Kalman filters to eliminate Mach delay timers, and cost less than $100. Stick a $5 accelerometer into a $100 altimeter and you get a Raven, or similar altimeter for ~$150.

Bob

Now that is interesting. Maybe I can try that with my RRC3's.

Chris

 

[4kids49]

Okay, I missed the buy in quantity part. Maybe Jim from MissileWorks or someone can buy a bunch and sell them to us.