Crazy Sparrow

Status: Kit - not built
Number of Views: 182

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Date added to fleet:
Total Flight Time:
Total Number of Flights:
Typical Flight Time:


38.0 in (96.5 cm)
Wing Area:
251.0 sq in (16.2 dm^2)
Weight (less battery):
16.5 oz (468 g)
Wing Loading:
9.5 oz/ft^2 (28.9 g/dm^2)
Cubic Wing Loading:
Center of Gravity:


himax ha2025-4200 w/horst 4:1 gearbox
TF or Rev-Up 9x5


This is an older model that I took about 3 years to find. Had to find a horst gearbox, but now have one so it's just a matter of mating a brushless motor to the gearbox. The kit is missing the original propeller so something will need to be worked out there as well.

Himax ha2025-4200 info:
Weight: 65g(2.3oz) Motor Only
Max Power: 175W (This is dependent on several factors)
Max RPM: 60,000 RPM
OD: 20.0mm, (.79”)
Length: 42.0mm, (1.68”)
Shaft Size: 2.0mm, (.078”)
Mounting Screw Thread: 2.5mm, max depth 3.0mm
Mounting Pattern: 16mm (.625”) bolt circle.
Maximum Case Temperature: 100oC, (212oF)
Electrical Specifications:
HA2025-2700 Kv = 2700, Rm = .169, Io = .47, Efficient Operating Current = 5-12A
HA2025-3200 Kv = 3200, Rm = .144, Io = .53, Efficient Operating Current = 6-15A
HA2025-4200 Kv = 4200, Rm = .075, Io = .75, Efficient Operating Current = 10-20A
HA2025-5300 Kv = 5300, Rm = .044, Io = 1.4, Efficient Operating Current = 15-25A

RC Groups Review:

In the day, guys were flying with 9x6 props. Came with about a 91/2-10x6 and 250 or 300 speed brushed motor depending on the kit.

Other power setups:
I found the best power option was a 5-1 gearbox (MPJet BB) 9x6 APC SF prop and a speed 300 motor

The gear is a lamination of 3 parts, one groved piece of wood, one piece of wire and one piece of thin ply. By adding a lamination of carbon fiber (either sheet or tow) to the gear lamination during construction the gear gains more than enough strength for all but the hardest of landings. Another very good up grade is to change the tires to light foam wheels.

Flight Duration Histogram


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