The 0.5mm Mistake That Makes a Whoop Prop Useless
Quick Answer
A tiny-whoop prop must match both the frame clearance and the motor shaft. Measure the prop diameter and the bare shaft with callipers before ordering. A 40mm prop drilled for 1mm is not interchangeable with the same-size 1.5mm version: the wrong bore either will not fit or will not grip.
Measure These Three Things Before You Buy
Whoop prop names compress several separate measurements. In “1.6×0.9×3”, 1.6 inches is the nominal diameter, 0.9 inches is pitch and 3 is the blade count. The shaft bore is a separate specification, even when two packets otherwise look identical.
Start with diameter. Thirty-one-millimetre props are common on 65mm whoops, 40mm props on conventional 75mm frames, and 45mm props on enlarged 75 Pro-style frames. Those are useful families, not permission to guess: check the frame’s specified prop clearance because ducts leave little room for error. Our wider FPV propeller size guide explains how diameter changes motor load.
Next, measure the motor shaft rather than inferring it from motor size. Current whoop hardware spans 0.8mm, 1mm and 1.5mm press-fit systems. A larger bore on a smaller shaft can slip; forcing a smaller bore onto a larger shaft can split the hub or load the motor bell. We would reject either bodge rather than add glue to a part designed for replacement.
Our Catalogue Shows Why “40mm” Is Not Enough
We currently stock both a HQProp 40mm 1mm-shaft tri-blade and a HQProp 40mm 1.5mm-shaft tri-blade. Diameter alone cannot distinguish them. The newer 1.6×0.9×3 version is listed at 0.25g per prop, with a 4.2mm hub diameter and 4mm hub thickness; those dimensions are useful identification clues, but the 1mm bore is still the deciding fitment.
| Example from our range | Diameter | Shaft | Use it to identify |
|---|---|---|---|
| HQProp 1.2×0.9×3 | 31mm | 1mm | 65mm-class fitment |
| HQProp 1.6×0.9×3 | 40mm | 1mm | 75mm-class, small shaft |
| HQProp 1.6×1×3 | 40mm | 1.5mm | Same diameter, larger shaft |
| HQProp 45mm tri-blade | 45mm | 1.5mm | 75 Pro-style clearance |
Choose Blade Count After Fitment
Shaft and diameter are hard compatibility gates; blade count and pitch tune how the aircraft feels. More blade area generally gives more grip and load, while fewer blades can improve efficiency. Do not treat “more blades” as an automatic upgrade: a motor, battery and tune built around a light bi-blade may run worse with a demanding quad-blade. Compare the trade-offs in our bi-blade, tri-blade and quad-blade guide.
Our buying order is simple: frame clearance, shaft diameter, rotation direction, then pitch and blade count. Browse the propeller collection only after recording those first two measurements. This prevents the most frustrating outcome in a small FPV repair: receiving props that are visually right and mechanically useless.
FAQ
Q: Can I drill a 1mm whoop prop to fit a 1.5mm shaft?
A: We do not recommend it. An off-centre or oversized bore creates vibration and poor retention. Buy the correct moulded bore instead.
Q: How should I remove a tight press-fit prop?
A: Pull evenly while supporting the motor bell; do not lever against the windings. Our whoop prop-removal guide compares fork and screw pullers.
Q: Must I match CW and CCW props?
A: Yes. Fit each prop’s direction to the motor direction configured on the quad. A mixed-up set pushes the wrong way and the aircraft will not take off correctly.