Can ANY altimeter handle the Apogee Aspire?

OpenRocket predicts a peak acceleration somewhere between 50-60G, and even with proper mounting of the AltimeterTwo, that altimeter can only handle 40Gs.

Can ANYTHING reasonably priced handle this?

Do you need an accelerometer type altimeter? Most barometric altimeters will work fine. My Perfectflight HiAlt45 handled several of my +80G flights with no issues. I wouldn't hesitate to use any of the Perfectflight altimeters in high G flights.

RocketRoll said:

OpenRocket predicts a peak acceleration somewhere between 50-60G, and even with proper mounting of the AltimeterTwo, that altimeter can only handle 40Gs.

Can ANYTHING reasonably priced handle this?

Click to expand...

The Altimeter Two can handle 60 G, it just that the accelerometer chip won't record any acceleration greater than ~40G, and the barometric altimeter chip will read the apogee altitude just fine. Since the accelerometer chip tops out at 40G and the accelerometer chip is used to determine the maximum velocity, you will not get an accurate peak velocity.

Barometric altimeters measure pressure altitude, however as a rocket crosses Mach 1, the pressure fluctuates rapidly as a shock wave moves across the pressure port. The computer program that calculates the rocket velocity using the barometric pressure sensor output looks for the greatest dP/dt, and this occurs around Mach 1 unless the rocket greatly exceed Mach 1. This error is not correctable, so you need to use a sim to obtain the velocity profile of the flight. You match the apogee of the sim by adjusting the Cd of the rocket to match the altimeter apogee and look at the velocity profile to get the maximum velocity.

Bob

My RRC2+ survived a ~ 90 G (for .3s) boost on an H669 without any ill effects.

Nate

The Raven is rated for 70G. Plus you can order with a special option for 250G!!!

les said:

The Raven is rated for 70G. Plus you can order with a special option for 250G!!!

Click to expand...

+1 for the RAven 250G. I have 2 of those. I haven't flown them yet but I do have a plan for them.

ideas-

https://cart.amwprox.com/index.php?...t_id=974&virtuemart_category_id=19&Itemid=474

https://cart.amwprox.com/index.php?...t_id=973&virtuemart_category_id=19&Itemid=474

The Raven will fit in a 29mm tube. Featherweight even sells an AV bay for it in that size (although you don't get all the channels). They even sell a 24mm version of the bay.
That plus getting the optional 250G version I would hope would be sufficient.

What folks need to understand it that while many altimeters can reach their recording limit during a rocket flight, the altimeter is usually not damaged.

I've gun-launched the 70G rated R-DAS Classic under 20 KG acceleration and they worked fine after that stress. (Note the altimeters were encased in wax to prevent part movement during the gun barrel transit.)

To see if the accelerometer chip has been damaged from an over scale acceleration, turn on the altimeter (has to be recording type) and tumble over 1 or 3 axis depending on the accelerometer chip used. Each axis should indicate a +2G differential on the data trace (+1G minus -1G = +2G differential.)

Bob