|Jan 31, 2011, 12:21 PM|
6 miles out, and back. Planning on the fly.
Maybe I should have titled it "31680ft!!!"
This is bit more long winded than I planned, but whatever.. Some people
provide too little info.. I provide too much.
I'm not a "long range" guy. I've generally only been looking for "solid" video
and control out 2-3 miles. But with the new Skywalker, on which I installed a little
higher powered video Tx (FOX800 putting out about 500mW at 1.3Ghz) and much
better tuned antennas, and a 2.4Ghz control system that seems to work better near
the UHF band Digital TV broadcast towers, I decided it'd be fun to try for one of
the benchmarks I had noticed while ground range testing various control systems. One of
the spots I always test from is exactly 6 miles from where I usually launch and fly.
The original plan, was to set up the Tx and ground station on the mountain I normally fly
from, and then have one of us take the plane in a car down the highway testing video
and control at various distances, using different antennas, power settings, etc.
Then pick the best combo and make the flight, keeping the plane low the whole
time (launch point is high, so can fly low). I'm also waiting for a 3S 5000mAh
pack and I had set a goal to make the 12+ mile round trip on that single battery.
That was the first best laid plan.
Sunday, we were sitting around on the slope watching the wind blow straight in
below us, but generate no lift to fly our slope planes, due to a heavy inversion.
Bored, I mentioned that we could do the antenna tests and my buddy was game.
Then I realized I hadn't brought my 13dB Yagi antenna and didn't really think I
could make 6 miles without it. Hmm.. what to do.. Antenna testing without my
best antenna? Wind lightened up to almost nothing, taunting me into making a
powered flight (it's rare when the wind doesn't blow hard in the winter here) ..
What the hell. I figured I'd go with my 4000mAh pack, 8dB patches, and just keep
flying until video got too scratchy, and turn around and/or battery ran low, and
land out somewhere in one of the many fields along the route and my buddy
in the chase vehicle would pick it up. So that was the second best laid plan.
He drove out to the north edge of town about 2.5 miles away, and then I
launched from the mountain (with two more flying buddies with me helping spot
and communicate with chase vehicle). Following is the whole 30 minute flight
in both HD and SD with my thoughts and reasoning along the way. Can see it
followed neither the old plan or the new, but I was happy with the outcome. Just
kept revising the plan as I went along.
single 3S 4000mAh battery pack.
total battery capacity used: 3300mAh
flight time: 29:45
Ave current: 6.65A
Furthest distance away: 6.0 miles.
Distance flown: about 13mi in the air (didn't fly straight to goal)
Average ground speed: 26mph
Vid Rxs: Rangevideo 1.2-1.3Ghz single output Rx with 17Mhz SAW filter mod.
Vid Tx: FOX800 on ch9 1.3Ghz with DBCAV low pass filter to keep 2nd harmonic out of 2.4Ghz band.
Vid Tx antenna: IBCrazy style inverted-V (simplest kind, just soldered shield ground into thin wire and pointed 120 degrees from core wire)
Vid Rx antennas: L-COM 1208, trimmed to better suit 1280Mhz
Oracle diversity. One patch on ground, one on tripod. Both were being selected
for extended periods even at furthest range. Patch on ground was angled back from
vertical about 30 degrees with sloped ground in front of it while patch on tripod
was 4 feet up and pointed straight down the route. Plane was below launch
for almost entire flight.
RC gear: RMileC 2.4Ghz at 1W with 5dB omni on Tx.
Cameras: RCV922 + GoPro HD.
No low battery indicator other than ESC's LVC (set a bit higher than stock).
I've still got control and video when motor shuts off and I'm a sailplane pilot,
so I'm always looking for places I can safely glide to.
Motor: Scorpion S-3008-28 1220Kv
Prop: 10x6 folding (had to raise mount on Skywalker for prop to clear boom)
ESC: Scorpion Commander 55A with 5A 6V BEC.
Only one torroid filter on the plane, comes pre-installed on Turnigy 5V BEC
that powers my flight camera and mic. No LCs.
Keep in mind this isn't a record *anything*. It's just a PB for me using what
I consider a fairly basic no frills setup. I'm quite happy with the performance of
the video gear and the plane. The video reached out way further than I expected
on 8dB patches and 500mW Tx power (just goes to show most folks probably do not need
the 1000-1500mW Txs they think they do). The RC gear performed about how I
expected, with a glitch here and there depending on position/orientation of the 5dB Tx antenna.
It's not even close to the performance of properly functioning UHF control system
free from powerful external RFi, but it works at the ranges I need, in the
nasty Rf environment I need it to. I'd like to make the flight again with a
little more battery margin, and flying much lower, if possible.
BTW, I'm flying the Skywalker with the CG 30-35mm behind recommended (behind
the wire slots in the wing), and it flies great. Dunno how the Skywalker got the reputation
as being so ridiculously tail heavy. Never trust the manufacturer's recommended CG.
Only weight I have in the nose is single 4000mAh battery (not even all the way forward
any more), and GoPro camera. I'll bet I can go further back than that with the elevator rates
|Jan 31, 2011, 01:24 PM|
What DVR were you using? Was it the lawmate?
Really good flight, looks like you could have gone much further without any video issues. It almost makes me want to get a skywalker.
|Jan 31, 2011, 01:27 PM|
It's the RCV922. It's only a 420TVL camera, but it biases its exposure for
the bottom 1/3rd of the frame, which means even when the sky is bright white
overcast (like it was yesterday) the ground is always visible, instead of dark.
We tend to refer to it as "the pilot's camera". Not the prettiest colors, but
you can always see where you're going.
All I did in editing of this vid was brighten the GoPro video track, which was pretty
dark, and darken the RCV922 vid which was a bit too bright.
|Jan 31, 2011, 01:31 PM|
about 9-10Mbit/s. You don't gain a whole lot by jumping from 720x480 to 1280x960
but it picks up every detail that's available in the SD signal, and it costs about
the same bitrate, so no reason not to use it.
start, but didn't degrade that much more at distance. I think the average quality
was a bit worse than the flight I did the other day from down below, because this time
the Rx antennas were up on the mountain in full view of the whole city, so they pick
up more external Rfi. But I was pleasantly surprised with the quality, 6 miles out.
I'm sure I could reach out double that distance with a good Yagi, tuned for 1280Mhz,
and not talking about doing it 5-10k feet up either.
|Jan 31, 2011, 01:43 PM|
Awesome flight info.
Can't watch the video now, but lots of info is good to me. Someone's bound to ask something and if you've covered it that's even better.
Now I have my after work entertainment. Thanks for posting.
|Jan 31, 2011, 01:49 PM|
closer to 13 when I include the circling I did 4 times along the route.
Other people had reported that this plane would cruise at around 7A, so I was pretty
confident that I could make it easily on a 5000mAh pack, if I could average 25 mph or better.
I knew it was *possible* on a 4000mAh pack but not at all confident, especially if
there was any wind. I didn't really notice the wind while flying, but chase driver said
he was doing 20-25ish most of the way out, and 35+ on the way back.
I'm thinking it'd be fun to throw a 2nd 4000mAh pack in there, and do it with about 50%
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