Just thought I’d cap off my build log with my first flight! This was a first in many ways. It was the first flight for me away from the area I’ve trained at. It was the first flight for me that I was completely on my own with no one coaching or correcting or telling me it was OK to go. It was my first zero wind launch. Beyond myself I’ve been reminded it was the first flight of an electric paramotor one the Sunshine Coast of B.C. Probably the first electric flight of any kind in the area. It was very likely the first flight of an electric paramotor in this province. OK enough firsts, on to the pics.
Setting up. Sorry I blurred out my helpers face there in a ridiculous way but I’ve not informed him that I’ve posted these yet so… Privacy and all.
One of 8 more inflation attempts. I was getting tired, and that wing was getting damp from the dew. I had lots more help than this one person too. I had a whole impromptu ground crew helping me reset each time. Finally…
FLIGHT!
The time spent not getting airborne chilled the batteries somewhat and it was barely climbing. Or maybe 6cell batteries isn’t enough for the Batch 4 motors/props combo. Hope a warmer day will be better. I’m at sea level.
Batch 4 is designed to use 7S so the biggest factor for lack of power would be that. Cold batteries will drop power a little bit but after a few minutes of flying they should warm up… how long did you fly?
6 packs of 6S (instead of 4 packs) will increase power a little because the voltage sag will be less but the extra weight might make that a trade off.
I’ve flown a batch 4 with 6 packs of 6S. Compared to 7S, it’s harder to takeoff and the initial climb out isn’t very good but the rest of the flight always felt very comfortable including dropping down into fields and climbing back out.
About 30 seconds. LOL. Just enough to get turned around and land. So the batteries probably didn’t really warm up. I didn’t want to push things if the batts were not going to be enough. I know from my model airplane years that cold LiPo batteries can turn a performer into a slug.
I’m about 80Kg dressed. I weighed the motor and batteries and the total is just over 25kilos so I’m around 105kg AUW. That’s the top of the range for my Buzz Z3 ML (23.5sqm) and it was damp. Climb was not great but it was steady at full power. The only other motor I’ve flown is a Blackhawk 125 but only with some wind which increases the climb rate over the ground.
I can probably correct this somewhat by going to more prop pitch (cheaper than more battery or batch 3 motors). Are there alternate prop choices available?
I think there is some performance data posted somewhere that had the 150kv motors with 6s and 22x14 props. It looked pretty close to the 180kv motors on 6s with 22x10 props.
Actually, another quick note: I was originally using a big 34x22 prop on my ultralight single prop build. That 3:2 diameter to pitch ratio is (usually) as coarse as you can go without having significant sections of the prop airfoil stalled on the ground. With my 34x22 I found that I was way over that line at 4000 RPM. It may be beneficial to get 22x13 (if you can find them) or 22x12 props instead of 22x14, just to avoid the prop stall. It makes the props very loud, can cause a lot of vibration if the stall is asymmetric, and I can imagine a lot of pitching and yawing being introduced as the four props stall and install unevenly. Whatever performance you lose from slightly less pitch will probably be compensated for by having a rig that is running smooth and (relatively) quiet.
I think DFDL sells 22x12 wood electric props on AliExpress.
I found those DFDL props. $37 a pair. Someone else on here ordered a set of props from DFDL and found them to be identical to the Gemfan props. It’s likely that they are coming from the same factory.
Got another flight in today. The day was a tad warmer, the sun was sunny, and it only took me three tries to get launched in calm air. Batteries were warmer for sure. Climb was good even though I’d not recharged at all from Sunday’s fun. Flew about seven minutes. It’s an amazing flying machine. Pictures forthcoming.
Quick disclaimer about the 22x12 props: those are specifically for the 150kv motors and 12s battery power. If you try them with 150kv motors and 14s batteries, or 180kv motors and 12s batteries, you may end up drawing too much current and smoking your motors and/or motor controllers.
As noted the extra pitch might pull too many amps if running seven cell packs (i.e. 14s, you’re connecting two packs in series). On a Batch 4 or newer X4 with the 150kv motors you’ll be safe with either 7 cell packs or 22X12 props but not both. On the older 180kv motors the 6cell packs (12s) and stock 22X10 props will be your limit and should be plenty of power. Thrust is advertised as similar to a 180cc 2 stroke.
Flight #2 pics as promised. Might post these somewhere else when there’s more flying and leave this as a build thread.
Starting the takeoff run. Again the wind is calm so it’s gonna be a run!
In the air! Looking good. Having trouble getting into the seat. Check where my right hand is. LOL I think I need to adjust the harness a bit somewhere.
Thanks - I thought the higher stated thrust was originally with 22x14 props but they drew too much power to be practical. I was looking at a compromise with 22x12.
All those numbers (thrust, electrical power, heating) are dependent on atmospheric conditions. For example, if you are @GliderPilot and live at 4500’ you may be able to run higher pitched props without drawing too much current because of the reduced air density. On the other hand, if you’re at sea level and it is 120F outside, even the 22x10 props could overheat your power system if you run it at full throttle for too long.
If you want to experiment your best bet is to use something like eCalc to find a prop that should work the best for you in whatever conditions you normally fly in. Then do some real world testing on the ground to verify eCalc’s predictions. THEN do some (ideally instrumented) flight testing to make sure nothing unexpected is happening in dynamic vs static (your ground testing) conditions. Making a guess about adding “a little more pitch”, throwing props on your machine, and blasting off into the wild blue is a recipe for disaster.
Even with a pre-built openPPG you are still to a certain extent a test pilot, and definitely are if you did your own build, and even more so if you are modifying it from the original specifications. In the professional flight test community, even small changes start with a lot of engineering and then go through a long process of testing and verification before they are flown. “Kick the tires and light the fires” test piloting killed a lot of people. Don’t let yourself be one of them.
It’s an amazing flying machine. Pictures forthcoming.
