Landing Gear Impact Accelerometer?

[Drkwing]

In one of our ongoing projects, a customer of ours have asked about landing gear g-meter. I said we would look into that, but I could not find an application so far.

This g-meter should record the vertical deceleration of the landing impact on the strut.

I would be very glad, if you can supply me a clue regarding this.

Best regards

 

[kontiki99]

What kind of data are you trying to capture? You can measure the collapse of the scissors link too.

 

[rb1957]

most planes measure landing impact gs at the airplane cg ...

you Could mount an accelerometer on the landing gear (if there's space, and route the cables to the data collector, but that sounds a lot more trouble than it's worth (unless the customer wants it that way, 'cause he's always right).

if you're looking for vendors, we've had good experience with SoMat.

whatever you do ... mount the accelerometer on a very stiff piece of structure

 

[crackman]

There's a ton of information regarding recorded data for landing impacts. Take a look at the FAA website for Operational Loads Monitoring:

http://aar400.tc.faa.gov/Programs/AgingAircraft/airbornedata/index.htm

One of the more recent ways of measuring the landing sink rates is to use digital video of the landing and determining from the images the amount of shock strut compression. All gears have a struct deflection curve and the deflection is directly measured from the images. Of course, strain gages are the standard as well.

James

 

[kontiki99]

crackman,

Your use of the term “sink rate” jogged something loose in my memory.

In a former life as an Instrumentation Engineer for Navy Flight Test we used what we called a sink rate pod to verify the build up to steep arrested landing approaches.

The pod contained a modified police radar (pointed down) with power supply, signal conditioning, and a transmitter. We received the data in a van parked nearby. It was plotted on a strip chart.

After every landing, the new piece of strip chart would go to the test conductor so he could see where we were in the series.

FYI,

Military flight test technical guidelines (Range Commanders Council) standards are on the internet.

You might find something useful here.

http://www.jcte.jcs.mil/rcc/PUBS/pubs.htm

Drkwing,

I don't know what your budget is like, but I'm sure if you contact the Test Article Preparation group at Patuxent River (PAX) they will be more that happy to instrument your aircraft for you.

 

[Drkwing]

Thanks everyone for the help. Special thanks go to rb1957... We have still not decided to install an accelerometer on the landing gear. Most of the applications use an accelerometer on the CG of the aircraft. If the accelerometer on CG is adequate, I think it will not be necessary to use on LGs.

Best regards,