Hi all, I'm going to be filming in higher elevations with the C8 (Colorado, Utah etc...) Need some advice. I already did some testing in Vail and that was around ~8000 ft above sea level, I noticed the effects on lift & power compared to sea level; shorter flight times, and slower response in performance. Need advice as to how to optimize and any additional tips would be greatly appreciated.
Welcome to Density altitude. While your base elevation in Vail was 8,000 any propeller driven machine didn't see 8,000 feet. On an 80 degree day in Vail the 'actual' altitude your CS thought it was flying in was closer to 11,000 feet. The flight altitude (density altitude) is a combination of field elevation, temperature and the air pressure. Quick little app for the iPhone is DenAlt. So if you need more lift then larger motors, perhaps a 5s battery. Longer flight times additional batteries in parallel. Or wait until winter .
Gary, thanks for the info. Great app! Now let's add some gusty winds into the mix and things should get rather interesting with the heavy payload consideration.
Make sure all the lipos are topped off and watch your temps - plus ridgeline winds can crush you. Avoid afternoons when the temps/winds are high. 5 years ago I put a single rotor Joker in some scrub brush from nasty winds even after full power/pitch in Telluride.
Im going to have to post some video of what happens when you fly at 8000+ ft and you get hit with some of those crazy updrafts!!! Lets just say I almost lost my copter and camera down a 2000+ ft cliff... twice... and resulted in 2 hand catches of the copter since I couldn't get it back on the ground safely... will NEVER do that again! BUT the footage from the second flight turned out awesome! Josh
We routinely fly at altitudes between 6000' and 12,000', which in summer means our density altitudes are between 8000' and 14,500'. The best tip is to lighten your load as much as possible; but you should have little trouble at 8,000'. Just be prepared for significantly shorter flight times. Don't rely on your barometric altimeter much either, because the winds will send you skyward in a hurry.
Here you go guys... My two flights to try and get one shot... only ended up getting it during the second flight because I just took off and flew straight up the mountain... then fought it the whole time to get it back. Anyways enjoy and I really wish I had a go-pro on the copter for this flight so you could really see what it was going through during these flights. At one point I was below 1/4 throttle to try and get the copter back to the ground and it would not come down! Then all the sudden the updraft would leave and the thing would just drop. I was then at full throttle to SLOWLY get the thing to slow back down. Both flights ended in hand catches by my camera op and I. I have never been shaking as much as I did after those flights. Flight 1: Flight 2: (this is the flight we got the footage on) And here is the final shot. (It's the opening 2 shots). Josh P.S. I don't recommend hand catching... not the safest idea BUT we really didn't have a choice if I wanted to keep flying the copter. It was too all over the place for me to try and land...
Josh - that is a challenging location indeed! Thanks for sharing the vids. We had a similar issue filming a bike race at 12,000' (DA was 14,500'). We flew out LOS about a 1/4 mile, then hit GPS home (while in a gusty updraft) and she took off like a rocket to 800' AGL. Thought we lost her for good. I desperately cut throttle to zero and she still climbed, then started settle out and was able to get it back. It was nothing but a tiny dot in the sky. Bottom line is that winds have a major impact on the barometeric altimeter (alternating high/low pressure), so the copter thought it needed to climb, and climb it did! Now we don't use any altitude funtions in windy conditions - too risky. We've got a video of it that we'll post soon... -Jon
Yeah I never use the alt. hold in winds either... even with it all "Packaged" it still changes to much. My flights were all on manual with no help. Scared the crap out of me!!! Can't wait to see your video too!
My palms are still damp, Josh. And I think I discovered, again, that adrenalin is brown. I used to fly a full sized sail-plane along mountain ridges using the lift to travel for hundreds of miles -- but the other side of that benefit is the so called Giant Hand. And you have to peel away into the valley as fast as you can if you get hit with the Giant Hand pushing you down. Were you on the up-wind or down-wind side of the hills? The winds will be really squirly on the downwind side as the air roils like water over a rock in a rapids. I've measured lift of 1,200 feet/min and corresponding sink in mountain air -- but we tended to stay on the upwind side, except when it was time to come back to land and we need to step on the "down" elevator so we'd drift down-wind for a bit. It's also incredibly bumpy air -- enough to stick crud from the cockpit floor on the top inside of the canopy. Thanks for sharing. Can I relax now? Andy.