1st Airborne LiDAR Control Project

Cool

Shelby... I helped develop and field prove some of the first versions of the PosPac software, and had Applanix PosAV units number 3 and 8. It is cool stuff... Did a lot of 100km plus trajectories, loosing lock and solving GPS ambiguities on the fly for relock. Some real challenging GPS post processing, but really if you use the GravNav processor you can tell if you have the right SV ambiguities solved. Not sure about using VRS, I suppose it will work fine, but short baseline distances from base to rover is not as important as collecting as clean of data in the airplane as possible. This means a good antenna location that minimizes multipath and signal blockage, proper flying so that wings and tail do not block GPS reception during turns, doing hard S turns every 5 minutes so that the yaw component gets some change rate to solve the z axis for the IMU drift and so on. Is your GPS antenna under the main rotor on the helicopter? That presents its own challenge if so.

I was working with Joe Hutton at Applanix to get a way to use the IMU data to carry the SV ambiguity count to carry through cycle slips. Basically a fully integrated solution using the IMU to solve the GPS trajectory, then reseed the trajectory thru PosPac to fully solve the IMU drifts. I miss doing that stuff, as it is so challenging and fun.... Thanks for the post.

Cool

does laying the stick over for a couple of steep turns make the cameraman sick?

Cool

@David, you do not want to do a high bank turn at all.... you want to do a flat skidding turn. High bank turns can put a wing up to block the signal to the GPS antenna, loose lock and you have to reinitialize the GPS ambiguities. what you need to do to prevent drift of the IMU gyro that relates to aircraft heading, is change heading through at least 15 degrees every so often, hopefully less than 5 minutes. So on long flight lines, where it is traditionally get a heading set to compensate for drift and hold it steady, you need to break that habit and make some flat S turns every so often so that the heading changes and the trajectory then has change in it to calibrate the IMU gyro procession during post processing. Easier to do with a helicopter if the antenna is on the tail boom as you can make nice flat pedal turns with the helicopter and really move the antenna around. Fixed wing you need to make the flat skidding S turns. Make sense?

Cool

Cool stuff for sure. When all said and done the statistics coming out of the software indicate errors of under 2 cm horizontal and under about 3 cm vertical for the 5+ hour flight. We were using a C310.

Applanix seems to be moving away from the GravNav processing engine, an Applanix OEM version still comes with PosPac, however that is secondary to their primary processor they call Infusion which is a tightly coupled solution with the IMU. They have several modes of this starting at the top end with what they call SmartBase which is basically a post process kinematic procedure using VRS technology allowing the aircraft to be up to 70 km from the base station. The PosPac Infusion processing seems to be easier to use, BUT they have taken away a lot of the tweaks you can do in GravNav.

I think the OEM GravNav version is mostly included for using GLONASS and for multiple base stations as the PosPac processor only allows a single base station to be selected either in the "VRS" mode or single baseline mode and only GPS satellites. I suspect that eventually they will get those items figured out too. I already owned GravNav and have been using it for years so am pretty familiar with how that works.

I haven't seen the helicopter installation so I don't know where the antenna is located, just got the data for post processing, I guess if the X lever arm is real long in the negative direction, I will know it is out on the tail boom someplace!

In about 1993-94 we were maintaining lock under the rotor disk on an R22 and able to maintain ambiguities for doing stop and go post processed kinematic. I think it was in 1994 that my former boss and I co-authored an article about this procedure in an article published in POB magazine.

SHG

Cool

Yes that makes sense.

My Dad flew photo missions in the 1960s and 1970s in a C182. He told me about keeping the wings level. I never got the chance to fly those missions; I talked to a company owner but I don't have whatever huge number of hours their insurance requires for their C206 pilot. I don't know where they find pilots that can afford to fly around in a C206 for a thousand hours before getting a paying gig.

I finally let my CFI go (it expired at the end of September). It has been so long and I figured if I was going to teach I would need training anyway so I might as well take the checkride again if I ever was going to give dual again. I still have the single engine commercial.

We just did the ground control for an aerial project. We set 4 primary control points and a bunch of panels. On the morning of the flight we ran our receivers on the primary control points at 1 second epochs (that made huge files) for the duration of the flight. They told us they would be done by 1pm. We saw the airplane fly by (a twin) about 12:45. We waited until 1pm then took everything down. I sent the coordinates and receiver files to the photo company and they are about to deliver the product. They wanted the coordinates of one of the primary control points so they could fly over it before and after to get the shortest baseline to the receiver to help calibrate their kinematic processing somehow.

Cool

You wouldn't get me in an R22. That helicopter has a terrible safety record. A friend told me in the late 90s he was considering learning to fly helicopters but the most common training helicopter was the R22 and 25% of them ever built had been in a crash. It seems to me a helicopter CFI told me the pilot has to be careful with the cyclic; if it is moved too rapidly the blades can come through the canopy.

R44-maybe.

Cool

OK I have to stop watching these videos; they make me want to drop a load of cash to go flying.

My Dad used to fly us into the Sierra Nevada backcountry in a C182; he would take off with the stall horn starting to complain like the river takeoff in the C180.

[flash width=640 height=360] http://www.youtube.com/v/R48L3_PPVrs&hl=en_US&feature=player_embedded&version=3 [/flash]

Bush Plane website

Infusion

... must be the tightly integrated GPS post-processing Joe was developing. I would like to see it sometime.

Bush Flying

David, that was not too impressive of a takeoff to me. I had over 3000 hours and 25,000 float takeoffs supporting survey operations in a Cessna 185 over ten years. Most in places nobody had ever taken a floatplane. I would have been out of there on the first run.

The cubs are really fun, I prefer big bushwheels these days. Here is a short video from two weekends ago. Foot of new snow on that runway today, so in town for this weekend

Supercub Takeoff

This is what a light SuperCub can do with a little wind

Breeden Cub takeoff

Or add a little water to assist coming in and really get short
Water Assist

Here is a shot from 1990 in a slough near Bethel, Alaska with worker Fritz. I think Daryl Moistner was on that job too working for me that year.

Bush Flying

That is some great STOL performance.

The Helio Courier with no wind assist. Notice the slats on the leading edge in flight, which slide out as the wing nears stall to improve lift.

Bush Flying

I never got to do any bush flying. A friend went up to Alaska and flew a C207 for a commuter airline. He said one time he picked up a native woman and maybe a couple of kids at some small town strip. The husband showed up aggressive and drunk at the airport just as he started up. So he turned the airplane towards the husband and gunned it which was enough to scare off the husband.

I don't know anything about floatplanes but it seems like if you could get a few feet off of the water but stay in ground effect then you would get climbing faster.

My Dad had a T206U (mid 1960s model) with a STOL kit. With the flaps down at 25° (including the ailerons) and lightly loaded you couldn't hold it on the runway.

Cool

> You wouldn't get me in an R22. That helicopter has a terrible safety record. A friend told me in the late 90s he was considering learning to fly helicopters but the most common training helicopter was the R22 and 25% of them ever built had been in a crash. It seems to me a helicopter CFI told me the pilot has to be careful with the cyclic; if it is moved too rapidly the blades can come through the canopy.
>
> R44-maybe.

You can and has happened you can cut off your tail in R44 under certain condition but you can in MD 500's as wells...the safety record of the Robinsons has far improved over the years and I have no problem flying in them ...they are fine and durable machines...

Infusion

Long story short...

My folks owned a 1967 TU206B. They sold it in February, 1994. Dad has since passed on.

My Mom just recently received a delinquent unsecured tax roll bill from the County Assessor (apparently they were going through their files and collecting old unpaid tax bills). So I had to find out when it was sold before March or April 1994 so we can prove they don't have to pay the property tax bill.

I paid $14 for a certified copy of the aircraft record on CD. It's pretty interesting going through the registration record. It is just like a chain of title but you don't have to search the grantor-grantee indexes like at the County Recorder. They put the record together for you. I have never seen that before.

That airplane has had a LOT of owners, particularly after the folks sold it. That is a very expensive airplane to own, too much maintenance and multi thousand dollar annuals. It was one of those things that a dealer at Bishop Airport hooked them up with the owner (who probably wanted out from under it) and they bought it. If they would've considered what they really needed even a C182 would have been much better for a private party to own and operate. They lived in Mammoth Lakes at the time (8,000 feet).