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Here is my latest power setup for F1Q/Electric B. The awesome power produced by this pkg. requires a very strong airplane in the 450 sq. inch range.
Motor : Scorpion 2212 – 1920
Battery : Fusion-Pack 800 mah 4S 25C 14.8 volt
Controller : Phoenix 25
Prop : See below
Hub : BB Aluminum, 32 mm pin pitch, 6mm root widthNo load test (no prop)
Volts—-Amps—-Watts—-RPM
16.3—-3.5
57
32,040Graupner 6 x 3 blades (6.7 actual dia. on BB hub)
Volts—-Amps—-Watts—-RPM
12.8—-28.0
358
21,540 (67% of no load speed)That is approaching Rossi 15 power. Probably exceeds a Supre Tiger 15.
What is the all-up weight for that package?Dan, Electric power component weights:
Motor
59.8 grams (Includes alum. mount plate + 3.5 mm bullet connectors.)
Battery—- 85.0 grams (Includes Deans Ultra connector on 3″ 16 ga.wires)
BB Hub
5.5 grams (Has collet clamp, no prop adapter needed)
Blades 6 x3 — 3.8 grams
P25 Controller– 17 grams
Misc. connectors–5 gramsTotal
176.1 gram (6.2 oz.)How does this compare to a gas motor; including prop, tank, fuel, and mounting hardware? Dick
I think all that weighs less than KB 3.5.
Add a mount and 3/4 oz of timer and the electric is definetly less.
A 15 package would most likely be more also.
2 1/2 minutes on 5 secs is becoming a very real deal.The Scorpion 2212-1920 is a very powerful motor. I currently have one on my test bench with a set of Graupner 7.5 x 4 prop blades on a Jim Jennings hub. I’m running it on a 3S, 800mAh, 35C pack available here in UK from Overlander as part of their Extreme series. I’m getting about 16k3 rpm at switch on. ESC is a Jeti 30A from the Advance plus range.
Don’t know if you guys have looked at the Scorpion website, but there’s a good, free software download called Scorpion Calc. There is a bit in it that lets you enter actual rpm figures for a wide range of props and comes up with a figure for the generated thrust. It indicates that this motor, with the 3S pack and 7.5 x 4 Graupner folder prop as described above, the thrust output is just over 1000gf. However, with a 6 x 3 Graupner folder on Dick’s 4s pack at 21.5k, the thrust generated is around 850gf, a significant reduction despite the greater voltage.
Cheers – Tony Shepherd
I’m having no luck finding the scorpion site.
Here’s a query: Assuming that I like the 3cell thrust figures, could this run on the 400mah 3cell pacK? Also assume that it only runs 10 secs or less.Dan, Try this: http://www.innov8tivedesigns.com/
Dan,
1. Jim gave you the correct link to the Scorpion website where you can see the motor specs, and download the motor calculator if you wish.
2. I don’t think a 400 mah 3S battery will work…not enough current capacity. This motor will draw 20+ amps with the 7.5 x 4 prop. Go with 800 mah.
Tony,
Thanks, you gave me the idea to try the Scorpion motor.
I think there is something wrong with your thrust calculations. Here is what I get from the Scorpion calculator for the 3S and 4S setups.
Prop
RPM
Thrust (gf)
Pitch Speed m/s
7.5×4—16300
1018
27.6
6.3×3—21540
1013
27.4
These numbers agree closely with the Badcock online thrust calculator. Note that the 3S and 4S setups give very similar results. 4S uses more watts input, but a small prop airplane is easier to trim. Take your pick.Hi Dick,
Yes, after I’d posted the previous reply I went back into Scorpion Calc and found the 6.3×3 which is probably closer to your arrangesment with the wider hub. Obviously I came up with the same figures that you did. Seems like a lot of difference for 0.3″!
I’m not sure as to how the figures in the programme are obtained – is it done mathematically, based around measured dimensions of the props or experimentally using actual props, under test on a bench? Another of the great, unsolved mysteries of our time!!!
The advantage of the 3s version is that the pack weighs in at 74g, which is a few grams lighter than yours – I must say that I was surprised to see such a light 4S pack – what’s the C rating?
Cheers
Tony,
My 4S battery is 25C, see first post.I suggest using the Badcock thrust calculator to check Scorpions’s thrust calculations. Find it here: http://www.badcock.net/cgi-bin/powertrain/propconst.cgi?C_prop=156&RPM=6500&Volts=0.00&Current=0.00&Watts=0.00&Height=+++0&Temp=20.0
Scorpion has two 6×3 folding props listed; (6.3 x3 and 6 x 3). I think the 6.3 x 3 is the proper one to use…. not because my hub is wider, but because the Graupner 6 x3 is actually bigger than 6″ even with a standard hub. I measured it as actually 6.5″ dia. with a Jennings hub.
When all is said and done the conclusion is still the same; the 3S and 4S static thrusts numbers are very close to equal.
If the battery is an 800mAh pack rated 25C, then 28A is well above the contiuous rating. Do these packs suggest a long burst capability or are you just pushing it above the limit when bench running?
Cheers
Tony, Yes, I know that 28 amps is above the batteries continuous limit (20 amps for 25C). The battery’s burst rating is 50C (40 amps) for 5-10 seconds.
My bench tests run for approx. 10 seconds. The battery gets warm, but not ridiculously hot. The performance actually improves on succesive runs, as the battery warms and IR goes down.
Actual flying will never have more than 20 second motor runs here in the States. I expect no problems. There will be some prop unloading in the air, as well as additional cooling.
My Phoenix 25 controller is also running over it 25 amp limit. No problem. Yes, I believe in pushing things for maximum performance.
Dick
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