Fort Worth, TX

About Me:

Aerospace Engineer with 27 or so years experience in aerodynamics and flight control.

Please tell us a bit about your UAV interest

I've been in RC for years, interested in autonomous flight DIY.



Activity Feed

Larry Grater commented on Andrew Rabbitt's blog post APM-guided High Altitude Glider Drop Simulation in X-plane
Paul, I don't really want to hijack the thread too much but you might want to look at the link above.  I did end up using FG for my HIL simulations.  With new versions of the code the SIL route might be best since you get better SW coverage. …"
Mar 22, 2014
Larry Grater replied to Max Messinger's discussion Enabling and using analog inputs
I was hoping someone else would respond since I'm not sure I did things right.  But, it worked.  In v 2.65 I followed suit in sensors.pde, modeled after the way the voltage pins are handled.  Then I had to extend the max_pin_sources in…"
Mar 10, 2014
Larry Grater commented on Chris Anderson's blog post APM-powered space plane has successful autonomous return from 100,000 ft
"Andrew,  I'm looking forward to 2.76 for the reasons you mentioned.  The current code writes a bunch of multi-rate data to an external SD card by way of UART2 and slows the fast loop to 38 Hz.  This is just barely enough but does work for HIL, UAV…"
Nov 20, 2013
Larry Grater commented on Chris Anderson's blog post APM-powered space plane has successful autonomous return from 100,000 ft
"Thanks for the kind words guys.  Over the next few weeks I'll post my mods to the stock Arduplane code.  Actually the roll rate feedback issue that resulted in the initial dive is fixed in 2.76.  The vehicle wanders about after controlled flight…"
Nov 19, 2013
Larry Grater replied to Andrew Tridgell's discussion APM:Plane 2.76 released
"Bravo to Andrew and the team on the DCM fix.
I'm positive that you've found the issue that eventually caused my 1st high alttiude return attempt (NTNS-2) to lose attitude reference (Link).  This flight experienced 2-3 Hz oscillations due in part…"
Nov 5, 2013
Larry Grater replied to A. Fleyfel's discussion Setting up stabilise mode to damp rotation but not auto-level
"This is fairly easy, but you will have to do some modifications to software to accomplish what you want.  The standard controller doesn't actually use the rate process variable but uses a standard PID.  The guys can correct me if I'm wrong here. …"
Apr 18, 2013
Larry Grater replied to paul riseborough's discussion A batch of faulty Pitot/Static probes - how to detect and fix in ArduPlane User Group
"Great write-up; and complete with a fix!  I found that all 3 of my probes leaked somewhat.  This one thing that may have contributed to measuring only about 1/2 of the dynamic pressure on my North Texas Near Space 2 flight.  My fix was a little…"
Apr 6, 2013
Larry Grater replied to Project Nadar's discussion Mission Planner Vibration Detection?
"On my last flight we pulled the sound track from the HD camera into Matlab and did a PSD.  There are likely free tools to do this.  Visible were the 1st and likely the second wing bending modes as well as the pitch oscillations that the plane was…"
Dec 27, 2012
Larry Grater replied to Darren Orange's discussion AutoPilot Glider(no motor) Released at 5000 Feet 2 miles from landing location...
"There are several pretty good discussions on the v2.67 thread that are relevant.  One part discusses airspeed control and that the code isn't really flexible enough now to handle gliders.  My observation here is that there's a flag in defines.h that…"
Nov 30, 2012
Larry Grater commented on Chris Anderson's blog post Weather balloon payload guides itself home (almost)
"There are several blogs and forum posts on this site dedicated to this topic. I'll likely be ready to fly again in a month. I got pretty far for a 1st attempt but had 4-5 issues, most of which are explained in the post flight charts. The end result…"
Nov 9, 2012
Larry Grater posted photos
Oct 22, 2012
Larry Grater replied to Tom Griep's discussion Setting UART2 on the APM2
"Tom, I don't think so.  What you have to do depends on your objective here.  The wiki explains how to route serial3 to UART2.  This tales a mod to APM_config.h and subsequent compilation.
#define TELEMETRY_UART2 ENABLED  // solder bridge changed to…"
Oct 15, 2012
Larry Grater posted a discussion
I'll preface by saying that I'm not a C++ developer.  There are multiple references to APM2/2.5 support for UART2 on the forum.  Most references don't seem to come to conclusion.  I think we have quite a bit of flexibility on how to utilize the HW…
Oct 12, 2012
Larry Grater replied to Tony M's discussion MPU6000 Accelerometer Setting
"Tony,  I'm also interested in this topic for gyros as well.  Part of my issues on the last high altitude flight were associated with gyro saturation and loss of the attitude matrix.  So, this is on the todo list.   Keep me up with what you find out…"
Oct 6, 2012
Larry Grater commented on Larry Grater's blog post NTNS-2 Flies to 88k ft with Stinger 64 Airframe (partial success)
"Update: I found a pinhole in the pitot dynamic proble.  This could be crash damage, a manufacturing defect, or an assembly issue.  Potenially significant to others is that I have tested both my DIYdrones AS probes and they both leak from the dynamic…"
Sep 8, 2012
Larry Grater commented on Larry Grater's blog post NTNS-2 Flies to 88k ft with Stinger 64 Airframe (partial success)
"This thread is really mostly about the data.  Not necessary, but completed was a range safety analysis that showed < 1X10-7 probabilities of a major issue with aircraft.  I haven't done the work but I believe it much more likely to hit a buzzard on…"
Aug 31, 2012