This is another good question and in my opinion it probably comes down to personal preference after considering what Vans recommends. The larger diameter will generate slightly more thrust at lower speeds. However, since the RVs already have excellent field performance, is the larger diameter absolutely necessary? The shorter prop will have lower fly-over noise if that is important to any of you? I feel the difference in cruise thrust will be relatively small. I understand that Van's recommends the 72" for all the TDs because of ground clearance. I don't know what the ground clearance is on all the various models? Perhaps some of you that have flying airplanes can read 14 CFR 23.925 and go measure it so everybody knows?
One thing that everyone should be aware of is we approve the prop from 74" down to 72". If you buy a 72" you essentially have no length repair tolerance left. If you prang the tip, you don't have any tolerance to grind-off the damage. However, most of the time when a tip is pranged it causes enough damage/bend to scrap the hub too (our criteria: if the blade is damaged/bent beyond repair allowance, the hub is considered scrap because of undetectable fatigue damage). Ironically, with a 72" prop you are less likely to prang a tip because you have 1" more clearance so the issue of repair tolerance is sort of moot. I know 1" doesn't sound like a lot but it could be the difference between a scrapped prop or not (remember, its the last inch of spaghetti that gets the sauce on your shirt
).
Speaking for myself, I would buy the maximum diameter available that meets established ground clearance criteria. How's that for a non-commital, politically-correct answer? I would be happy with either prop.
I should have the approval/placard summary done early next week. I will provide it to Vans and post it in a new thread.
Les
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Linear Mode
