The International Cessna^® 170 Association

I stumbled up on a prop that I might be interested in. I am curious for those in the know how a 7649 prop would perform on a Ragwing 170? I know cruise speed would be around 100mph. What would the climb rate be? How much would a prop like this normally go for in good condition? Thanks in advance for the input.

AK170Ragwing wrote:I stumbled up on a prop that I might be interested in. I am curious for those in the know how a 7649 prop would perform on a Ragwing 170? I know cruise speed would be around 100mph. What would the climb rate be? How much would a prop like this normally go for in good condition? Thanks in advance for the input.

That is such a good question! Each airplane has its own personality, of course, so it’s difficult to give you particular numbers for predicted performance…(and especially since you didn’t mention what prop you currently have and what performance you’re seeing with it) … but I’d guesstimate you’ll see about 100 fpm and 4 mph difference for each 1” change in pitch.

By the way, you are talking about a DM or MDM 8-bolt McCauley presumably?

What do you mean by “good condition”…?? Will your “new” prop come with a FAA 8130-3 tag…and a log-record and history of inspections? Beware of online-auction props with no records from sellers you don’t know. I’m aware of one of our friends who discovered he’d purchased a prop which had been bent, then straightened by an individual who was not an authorized propeller repairman. It’s a wall-hanger only now.

A 7649 would be considered a seaplane prop in '49 when the A model came out and was certified as a PCSM which the '48 never was. What this means to you is the 7649 would likely spin out of the allowed static RPM range for a '48 PCLM. A 7651 was considered a normal climb prop.

Good morning Bruce,

Yes, it's a DM 8-bolt McCauley prop. Seller is saying that it has 350 SMOH and has all the paperwork with it. I have a 7652 prop installed on the airplane right now (prop currently on my airplane shows that it was re-pitched back in 1989 I believe). As far as performance numbers with that prop, I wouldn't know. I bought the airplane with corrosion on the camshaft and it is getting ready to get sent off for rebuild so I haven't flown the airplane yet. I'm not really sure what the going rate is for a prop like that so that is why I was asking.

There is no “going rate” that I’ve noticed. Salvage yards ask 50% of new. Univair offers a new McCauley DM7652 for $5400 so that may be a starting-point for you.

https://www.univair.com/aeronca/view-al ... propeller/

They sell for what someone is willing to pay..... The asking prices for 170's now, is crazy. I just wonder if they are selling for the asking price?

I've got a 7649 prop on my ragwing and can tell you it does not have quite the performance of a seaplane prop. I have flown side by side with a friend who has one and mine is slightly faster and doesn't climb quite as well.

Running hard I'm seeing around 110-115mph. Feels great pulled back to a calm 2100rpm cruising around 90mph cruising around at 500'.

I'm in Oregon, happy to give you a ride!

alanbaker wrote:I've got a 7649 prop on my ragwing and can tell you it does not have quite the performance of a seaplane prop. I have flown side by side with a friend who has one and mine is slightly faster and doesn't climb quite as well.

Running hard I'm seeing around 110-115mph. Feels great pulled back to a calm 2100rpm cruising around 90mph cruising around at 500'.

I'm in Oregon, happy to give you a ride!

If I'm ever in Oregon I will definitely take you up on the offer! What kind of takeoff distance do you think that you would see near sea level? What kind of climb rate do you typically see? I'm just wondering if it would be worthwhile to buy another prop. Thanks for the insight!