UltraProps.com
(Other prop/engine combinations not specifically listed may be extrapolated from this proven list)
Engine (Aircraft) | HP | Reduction Ratio | Prop | Diameter* | Pitch** |
R503 DC | 52 | 2.58:1 | 104 | 59" | 15 or 16 |
R503 SC | 48 | 2.58:1 | 104 | 59" | 14 or 15 |
R447 (best) | 40 | 2.58:1 | 104 | 59" | 13 or 14 |
R477 | 40 | 2.58:1 | 104 | 59" | 16 |
R377 (best) | 35 | 2.58:1 | 103 | 59" | 13 or 14 |
R377 | 35 | 2.58:1 | 104 | 59" | 11 |
R277 | 28 | 2.58:1 | 103 | 59" | 10 or 11 |
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Engine (Airboats) | HP | Reduction Ratio | Prop Kit # |
Diameter | Pitch |
Honda/B&S | 13 | direct drive | 103 | 36" | 13 |
Honda/B&S | 20 | direct drive | 103 | 42" | 15 or 16 |
Honda/B&S | 20 | direct drive | 104 | 42" | 14 |
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Engine | HP | Reduction Ratio*** | Prop Kit # | Diameter | Pitch |
Hirth F33 | 28 | 2.5:1 | 103 | 59" | 10 or 11 |
Hirth F33 | 28 | 2.5:1 | 103 | 52" | 17 or 18 |
Hirth F33 | 28 | 2.5:1 | 102 | 59" | 13 or 14 |
Hirth F33 | 28 | 2.5:1 | 102 | 55" | 17 or 18 |
MZ 34 | 27-32 | 2.34:1 | 103 | 57" | 10 or 11 |
MZ 34 | 27-32 | 2.34:1 | 103 | 52" | 15 or 16 |
MZ 34 | 27-32 | 2.34:1 | 103 | 49" | 17 or 18 |
MZ 34 | 27-32 | 2.34:1 | 102 | 59" | 10 or 11 |
MZ 34 | 27-32 | 2.34:1 | 102 | 57" | 13 or 14 |
MZ 34 | 27-32 | 2.34:1 | 102 | 52" | 17 or 18 |
*Increase pitch by one degree for every one inch decrease in
diameter.
**A change in pitch of one degree is worth about 200-300 change in engine RPM. Increasing
pitch will decrease RPM. Decreasing pitch will increase RPM.
***Other lower reduction ratios are available.
NOTE: If a loud "buzzing" noise is noted at high RPM with high-pitch blocks, it is because the tips are stalling. Do not operate the propeller in this range. Either a lower pitch or smaller dia. prop must be used.
Tests have shown that at and below 52-in. dia., no blade tip stalling will occur with 18-degree pitch blocks below the rated 3100 RPM.
Between 52" dia. and the full 59" dia., the approximate tip stalling RPM or onset of buzzing is shown in the table below for various pitches.
Diameter |
18 deg pitch |
16 deg pitch |
14 deg pitch |
59" |
1900 RPM | 2400 RPM | 2700 RPM |
58" |
2050 | 2450 | 2700 |
57" |
2100 | 2700 | 3100 |
56" |
2250 | 3100 | --- |
55" |
2400 | --- | --- |
54" |
2550 | --- | --- |
53" |
2800 | --- | --- |
Ultra-Prop 1 Propeller RPM Limits
Prop Diameter | RPM Redline |
59 inch | 3100 |
54 inch | 3300 |
48 inch | 3600 |
42 inch | 3950 |
36 inch | 4200 |
30 inch | 4500 |
24 inch | 4750 |
This information is provided courtesy of Competition Aircraft Inc.
USA Telephone Number:
+1-251-609-0969
Our Email: hoverhawkcorp(at)gmail.com
Copyright 2021