Changing props for high altitude flying

[DucktileMedia]

I have a job coming up where the altitude could be above 7000 feet. I usually fly 12" APC sf's on 2814's 4s. If I switch to 14"SF do you think this is enough to compensate for the 7000' difference? I flew graupner 11's on my y6 at 7000' a while back and the thing was 100% throttle coming down and landed hard! Normally I would never push to 100% or it would be lost in a few seconds. I was amazed at how big of a difference it really makes. Is there a rule of thumb for how much to increase per certain elevations? Any experienced input would be greatly appreciated.

thanks

Yuri

 

[ghaynes]

Yuri may not be necessary. Performance degrades approximately 3% per 1000 feet. But lots of us are flying in Colorado at or above that altitude with no detrimental effects. What does eCalc tell you for reference.

 

[Tomstoy2]

My Hexa weight is rather on the fat girl side of things, deffinately over the recommended weight limit I'm sure, though I've never weighed her. I regularly fly above 10000 feet and have had it up to 13000 feet before without modifying anything. Performance was only marginally decreased.

 

[DucktileMedia]

I was flying a y6 on 2814's and graupner 11's. The heli, at sea level, had gobs of power. But at 7000' it was barely able to land without crashing down. at 100% throttle it hit hard enough to bend the landing gear a little! I come back home and it flies normally again. I know graupners dont have a lot of surface area but I must have been right on the edge of lifting power.

 

[Tomstoy2]

Jeez, a y6, you really must be at the edge of weight to power there. If it was a battery thing, you would have know when you came back down. I do fly slo-fly props, so that could be the factor. Graups are pretty thin. Plug the data into ecal and see what difference the props make?

 

[DucktileMedia]

That's how I roll! I live life on the edge!

 

[tstrike]

Guys fly their cs's up at Brighton all the time and its almost 9000 ft. Slow fly props though.

 

[Tahoe Ed]

Yuri, When I go from Vegas to Tahoe and fly at 6500 feet, I find the graupners lack sufficient lift. I have put the DJI props on in those cases. I would increase the pitch if you can over the diameter. I found that my Discovery was very happy on 9" graupners and 4S at that altitude.

 

[meme]

I flew with AD6HL at 9000 feet and the Disco at 12.000 feet+ with a CX on Board and 9`Graups. I saw no changes on both copters as for lift, only more jello on the disco.

 

[DucktileMedia]

Well, thanks for the input guys. I guess I will have to just try again. I'm pretty damn sure it was the props and not something else like lipos. But I will bring assorted props if I drive that far to shoot next time.

 

[RancherPete]

Well, thanks for the input guys. I guess I will have to just try again. I'm pretty damn sure it was the props and not something else like lipos. But I will bring assorted props if I drive that far to shoot next time.

Yuri: I came across this thread because I wanted to see what guys were doing to make their MR do better at higher elevations. As you know I have the S800 and I live and I generally work at 7K-8K MSL. I have had to strip my machine down considerably in order to get it to lift my small Sony NEX5N and AV200 gimbal. In order to have a predictable hover I can run only ONE 5,000 mAh lipo other wise I must continually play with the throttle which drives me nuts. Even when I dial the vert. gain way up in the Assistant it is still not happy. I have been flying fixed wing aircraft for over 30 years and know that density altitude is always on your mind when flying so why should these smaller craft be any different when all of the same principles apply? When I take off from Durango I need twice the runway that I need at Van Nuys. Usable load and density altitude are big considerations with anything that flies.

For this reason I want to build a new HEXA that will be capable of carrying a greater load. I can't keep working like this, with 6 minutes of flight time and a tiny camera. Since I am starting from scratch I am looking for advice on the best motors, props and ESCs for this elevation and that will be less likely to wimp out up here. Does anyone have any thoughts or advice on this that they are will to share?

Also, Yuri; Check out the "Smooth Gimbal Controller" from Jakub! Absolutely amazing! Less $$$ than HFG and sooooo much smoooother!

 

[Breezemont]

"Smooth Gimbal Controller" from Jakub!

€200.00 ???

 

[DucktileMedia]

whats the link? is it a brushless controller? My hovergimbal works pretty well. Trust me I would complain if it didnt. RancherPete, if you want more oomph get an octo, dont build another hex. You should move back to LA where it is sea level

 

[RancherPete]

whats the link? is it a brushless controller? My hovergimbal works pretty well. Trust me I would complain if it didnt. RancherPete, if you want more oomph get an octo, dont build another hex. You should move back to LA where it is sea level

Yuri, Here is the link to the Smooth Gimbal controller thread: http://www.rcgroups.com/forums/showthread.php?t=1828803&page=13 . This is very new and while it is for servo driven gimbals the results are great. The configuration software offers tons of customization setting but he is coming up with pre-configurations for popular gimbals so that you can get going right out of the box. It's less money than HFG too by $125 or so if I remember correctly. Regarding the hexy vs. octo: I dread the idea of having to build an octo because it will be a monster! With 15" props the span will be over 1,000 MM to keep the blades from hitting one another. Do you really think that an octo is the only way to fly at 7-8 thousand ft. MSL? I did think about moving back to LA but that would put me closer to you and I'm sure we'd get arrested together within a week of hanging out

 

[DucktileMedia]

Go XY8! cant beat it. Solves many issues you speak of.

 

[RancherPete]

Go XY8! cant beat it. Solves many issues you speak of.

Yuri: Wow, I forgot about those twin engine jobs (over and under). I am not sure though what XY8 means. I think X8 is basically like a quad but with the four additional motors but I'm not sure where "Y" comes into it. Can you point me somewhere that I can get more info on this setup? For example I heard that the props on the top had to be a different size than those on the bottom (?) so this leaves me wondering where do I start with regard to sizing my motors, props and ESCs. Like this stuff is not complicated enough already This might be a great solution to my need for greater lift without building a monster craft that's a mile wide.

 

[DucktileMedia]

Seacrh for Bart's Xy8. he is the inventor of this configuration. It works so well I am surprised others havent stole it yet. basically the "y" is the 120 deg spacing as a Y6 would have but 8 motors on 4 arms. If you took 2 arms off the front and back of a hex you would have an XY8. You will never see props, and can even point the camera up! Small footprint, great lift, great in wind, great redundancy. Its only downsides are slightly less efficient and the lower props can show in a pan if you are using a 360 gimbal. Other than that it's a no brainer.

 

[RancherPete]

Seacrh for Bart's Xy8. he is the inventor of this configuration. It works so well I am surprised others havent stole it yet. basically the "y" is the 120 deg spacing as a Y6 would have but 8 motors on 4 arms. If you took 2 arms off the front and back of a hex you would have an XY8. You will never see props, and can even point the camera up! Small footprint, great lift, great in wind, great redundancy. Its only downsides are slightly less efficient and the lower props can show in a pan if you are using a 360 gimbal. Other than that it's a no brainer.

That was a great explanation, Yuri. Many thanks! I will dig into this.

 

[RancherPete]

That was a great explanation, Yuri. Many thanks! I will dig into this.

My only issue may be that this might not work with WKM. I have a brand new Wookong sitting right here for the new build and I'm not sure if DJI would allow for this Spyder design. I'm still reading and perhaps someone will address this question as I dig deeper.
Oops, it looks like WKM will work with the asymmetrical design from what I just read.

 

[SMP]

Hey Pete,

Where did you read this? Assuming its a custom configuration in WKM?? Modded the AD6 hexa in this exact same way - Coax mounts, 8 motors, lost the front and rear arms. Looks more like a sideways H. Haven't flown it yet. Love the footprint and hoping it becomes a "backseater" with the ability to lift a 5D2.