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Help! Battery/prop efficiency Sky Fly Max Newbie

#1
Hey fellow aviators, I just got into the hobby and have built two different FT models but just picked up a Sky Fly Max ready to fly for $50 to get me into the next level of performance from my simple cub and 4 channel. My question is how to get some more efficiency out of it and longer flight times. Its currently running an 1800 3c and a 9" S-2 Master Air Screw prop. Can I run a bigger battery and maybe a different prop? how about a 9" three blade to bring the rpm down? Im new at all this, having a lot of success flying but don't know a ton about all the other little things. Was getting 15-20 min out of the 1800 battery in my simple cub, RIP.
 

FastCrash45

Well-known member
#2
I'm not sure adding a blade to the same size prop would be right. I am fairly certain it would add to the current draw. I think you'd want less pitch on the prop but I am no expert on these things. Just giving you my gut instinct.
 

DamoRC

Well-known member
Mentor
#4
Hey fellow aviators, I just got into the hobby and have built two different FT models but just picked up a Sky Fly Max ready to fly for $50 to get me into the next level of performance from my simple cub and 4 channel. My question is how to get some more efficiency out of it and longer flight times. Its currently running an 1800 3c and a 9" S-2 Master Air Screw prop. Can I run a bigger battery and maybe a different prop? how about a 9" three blade to bring the rpm down? Im new at all this, having a lot of success flying but don't know a ton about all the other little things. Was getting 15-20 min out of the 1800 battery in my simple cub, RIP.
Its a simple question but probably a very complicated answer. To get longer run times you want to be able to draw lower amps for enough thrust to fly to your liking. As others have said, the extra blade would typically be less efficient. Lowering the pitch could help (don't know what pitch you are running now) but this is just a generality - you may find a prop with the same diameter and pitch, but a different style that could improve your efficiency. Ultimately it depends on what you want. If you are absolutely focused on flight times, then never have the throttle over the amount needed to keep her in the air and fly slow circles. Sure - you'll be in the air longer but will it be as much fun?
Really the only way to find a better prop in this instance is to try different props.

One the battery question, yep, you can theoretically get longer flight times with the bigger battery provided you do not add so much weight that you have to be flying at high throttle values all the time, maybe more fun, but less flight time.

So what are the specs on the plane / motor / prop etc?
 

FDS

Well-known member
#5
Also part of the deal with small electrics is that you can’t fly for super long periods without landing, like you can in a big gasser.
No matter what you do there will be a point where physics means you can’t get more potential energy on board and still fly. On the plus side electric pilots get more landing practice. Buy lots of batteries!
 
#6
Its a simple question but probably a very complicated answer. To get longer run times you want to be able to draw lower amps for enough thrust to fly to your liking. As others have said, the extra blade would typically be less efficient. Lowering the pitch could help (don't know what pitch you are running now) but this is just a generality - you may find a prop with the same diameter and pitch, but a different style that could improve your efficiency. Ultimately it depends on what you want. If you are absolutely focused on flight times, then never have the throttle over the amount needed to keep her in the air and fly slow circles. Sure - you'll be in the air longer but will it be as much fun?
Really the only way to find a better prop in this instance is to try different props.

One the battery question, yep, you can theoretically get longer flight times with the bigger battery provided you do not add so much weight that you have to be flying at high throttle values all the time, maybe more fun, but less flight time.

So what are the specs on the plane / motor / prop etc?
So the plane is a sky fly max the motor is 1300kv, 8x4 master air screw S-2 and 1800ma 3 cell. I am a beginner so cruising around at slow speeds is what I'm doing for now. I also built (and destroyed) a simple cub and now have just finished a simple scout. The scout has a cobra 1350kv. I haven't flown it yet cause the weather is windy. I think that some of the inefficiency with the sky fly is that it is a pusher and not a tractor.
 

Attachments

#7
So the plane is a sky fly max the motor is 1300kv, 8x4 master air screw S-2 and 1800ma 3 cell. I am a beginner so cruising around at slow speeds is what I'm doing for now. I also built (and destroyed) a simple cub and now have just finished a simple scout. The scout has a cobra 1350kv. I haven't flown it yet cause the weather is windy. I think that some of the inefficiency with the sky fly is that it is a pusher and not a tractor.
Maybe I can run a slightly bigger battery?
 

DamoRC

Well-known member
Mentor
#8
From what I can find, your wing loading is reasonably low so you could probably go to a 2200mAh pretty safely (if it will fit). The additional weight from an 1800 to a 2200 would only be a couple of oz which should be no biggie for this size plane.
 

FastCrash45

Well-known member
#9
So the plane is a sky fly max the motor is 1300kv, 8x4 master air screw S-2 and 1800ma 3 cell. I am a beginner so cruising around at slow speeds is what I'm doing for now. I also built (and destroyed) a simple cub and now have just finished a simple scout. The scout has a cobra 1350kv. I haven't flown it yet cause the weather is windy. I think that some of the inefficiency with the sky fly is that it is a pusher and not a tractor.
Nice looking fleet!!
 
#10
So the biggest problem I guess is that it feels a little anemic. I am surrendering to the fact that about 10 min is the flight time limit. But I did get an 8x6 pusher prop for it. Haven’t flown it yet (hopefully tomorrow). Hoping that will give it some more punch and bring the rpms down to maybe be more efficient at lower throttle settings.
 

DamoRC

Well-known member
Mentor
#11
The higher pitch will give you higher top end speed, but not more punch and is likely to draw more current for the thrust generated. Just so happens that I am in the midst of testing the new FT Radial C pack and running a number of props on it. Also testing an NTM 2826 1200Kv as a comparator. I have 8x4 and 8x6 props on test and, yes, the RPM will come down but the current draw increases. Thrust per watt is about 10-15% less with the 8x6 compared to the 8x4 on both motors.
 

Arcfyre

Well-known member
#12
The higher pitch will give you higher top end speed, but not more punch and is likely to draw more current for the thrust generated. Just so happens that I am in the midst of testing the new FT Radial C pack and running a number of props on it. Also testing an NTM 2826 1200Kv as a comparator. I have 8x4 and 8x6 props on test and, yes, the RPM will come down but the current draw increases. Thrust per watt is about 10-15% less with the 8x6 compared to the 8x4 on both motors.
I'd love to see a detailed chart of your findings when you've finished collecting data.
 
#13
What about a slow fly? They seem to have a ton of tractor like power on my scout. But the speed envelope is limited. I may just need to go to a bigger motor on the skyfly or just move to a different model. I’m finding I’m progressing seemingly quickly.
 

DamoRC

Well-known member
Mentor
#14
What about a slow fly? They seem to have a ton of tractor like power on my scout. But the speed envelope is limited. I may just need to go to a bigger motor on the skyfly or just move to a different model. I’m finding I’m progressing seemingly quickly.
It all depends on what you want. You can have fast, you can have 3D hover, you can have long flight times, but it's hard to get a motor, prop, battery combo that will give you all three at the same time in the one plane.
 
#16
Thanks for all the advice. I think I'm over this plane. just isn't that fun to fly. I tried the 8x6 and it really didn't change anything. I like flying my scout much more. I am finding that it is very acrobatic an still super forgiving. I also just bought a nitro set up for $90 used. Came with everything to fly and a flight box with electric starter and all. I'm gonna keep pushing the scout for a while and then fly the nitro plane. I'm defiantly intimidated by it but it is a trainer and they guy I bought it from said its super mellow.