Props for O-300 M4

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zamfire
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Props for O-300 M4

Post by zamfire »

I have the O-300 powered early version of the M4. It is equipped with a 74/60 prop, which seems highly unsuitable for this engine/airframe combination.

Static rpm is about 2200rpm. During take off roll it gets to a little above 2300rpm and only if I do a very shallow climb will it ever reach 2400. At those rpm's that equates to about 80 (2200rpm), 88 (2300rpm) and 100hp (2400rpm). Seems to me the prop is way over pitched for what is supposed to be a STOL aircraft (within the limits of its engine). There are 45hp left in the engine which I can never get to.

Does anyone have some real life figures for using a 76" dia. prop around 51 to 53" pitch? They are on the TCDS, so it's an option. It's what the average Cessna 170 used with the same engine. Whatever made Maule pick this prop for the M4?
1965 M-4 Jetason, O-300 Ser.no 089. Flabob CA.

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Mog
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Re: Props for O-300 M4

Post by Mog »

I don’t have much to say about different props, but I can say an O-300 M4 is really an eco cruiser not a STOL aircraft. Surely it can land stupid short due to weight, but it will never get out of the tightest places it’s capable of landing.

What’s your cruise speed and fuel burn?

zamfire
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Re: Props for O-300 M4

Post by zamfire »

I get about 7-8 gallons an hour at 100-115mph. At 2300rpm even less than 7, but then you're crawling along.
1965 M-4 Jetason, O-300 Ser.no 089. Flabob CA.

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Mog
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Re: Props for O-300 M4

Post by Mog »

Yeah, eco cruiser for sure.

Faster than a cub of its time
4 person plus luggage
In expensive to repair
Sips fuel still

It’s a good airplane, just not a STOL aircraft in today’s terms. I think you are better off trading in for something more aggressive or sleep good at night knowing you get better burn than me in my 220hp M4.

perkak
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Re: Props for O-300 M4

Post by perkak »

I have #9 for 23 years now
Using a wood 80/40 prop
2500 rpm - @ 92mph if you're lucky and approx 8 gallons per hour
Land in the 250' range but will need 400' to get off on the best day, more now that the motor is old and tires.
You'll only get 125hp at the prop with this motor.
Fun, looks cool and economical but not STOL

zamfire
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Re: Props for O-300 M4

Post by zamfire »

Interesting. I don't see an 80" wood prop on the type certificate; was this done on a one-off basis?
1965 M-4 Jetason, O-300 Ser.no 089. Flabob CA.

perkak
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Re: Props for O-300 M4

Post by perkak »

Field approval 337. I don't know model number off hand but if interested could get it for you. Sensenich prop.

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