Senior Master Sergeant
- May 13, 2018
You will love the YO-3A.
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I believe, but could be wrong, that you also need more blade area at high altitude than low altitude.But, there comes a time when the horsepower generated makes 4-blades necessary,
ThomasP,There was a production variant of the PV-2D with an 8-gun nose. There was a large order for them near the end of the war but only 35 were delivered before the end of the war and the contract being cancelled.
View attachment 701122
The above dwg is from the Warbird Information Exchange website, the thread is about the restoration of a PV-2D.
"Warbird Information Exchange • View topic - PV-2D Harpoon 84062 (Tanker 101) comes back to life"
There are a lot of very good pictures and some very good information.
Sources, please.It depends how fast you want your prop to spin. More blades are more efficient for a faster-spinning prop.
Thanks. Am just a dumb old pilot. Never heard efficiency at higher rpm was improved by more blades. More blades for sufficient blade area at high power and rpm, yes, but I always though for pure efficiency the fewer blades the better. More blades and/or wider blades were dictated by tip speeds and ground clearance. But I just fly them.The dwg I posted is from the thread I linked in the post. Unfortunately, I do not have the manual.
Knew a flying priest who bellied a C-210 onto a snow covered strip. Jacked bird up. Sawed off the bent portions of the blades. Flew .5 hr. to shop. I was there. He said the 520 ran up to 3500 rpm at normal cruise speed. Head mechanic told him, "Father, you're gonna kill yourself." Flying friar, "Oh, you know who my copilot is." Mechanic: "Yeah, and you're gonna kill him too."I worked on props and sometimes had to trim damaged blade tips .The trim had limitations for prop diameter. If it was within diameter limits.the blade angles would be twisted at the blade stations ,which also had limitations, thickness and width..Sometimes I would have to change Ham Standard blades on crop dusters, 2D30,12D40,to paddle blades and they would see a marked increase in speed across the field with greater nose up for wing over. “If they missed the electrical cables”…
Nice post but shouldn't it be "fewer blades is more efficient"?A long, skinny blade is more efficient than a short, fat one, and fewer blades is less efficient than more blades.