Climb prop

[bigrenna]

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[docfoley]

Where are you getting the props? Are you buying them new?

[Bill Hart]

A better question is what are you doing with your cruise prop. I have an 8 bolt flange and would really like to find a serviceable 7655.

[bigrenna]

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[Csudtell]

I still have mine and think I am going to keep it because of the same reason bigrenna stated. I could sell the 8042 separate if I ever sold my plane. I paid 3800 at Dominion Propellers in Anchorage brand new. They may still have a few in stock.

There is one for sale on Barnstormers now a 7655 just refurbished for 1600. Guys name is Tim.

[bagarre]

If only the STC covered the 6 bolt crank

[robw56]

I had my 76/53 with 200hrs on it for sale on barnstormers for $1500... no one wanted it so I ended up selling it to a friend for 1k.

[robw56]

If you're talking about the one on Barnstormers it's a DM and its a 76/54. Browse adds for Cessna, then 170, and you will find it.

[GAHorn]

Like many internet sites...be forewarned buying aircraft parts there.

"As removed" parts...and parts with "old" tags (so-called "yelow tags" or 8130 tags) ...can mislead one into believing a part is airworthy, when in-fact it is not. (Any "fresh yellow tag" should be investigated by calling the CRS issuing the 8130-3. Those tags are sometimes bogus.)

We have several Members who have been burned when they bought parts, including items such as props and gear legs, from barnstormers and found them misrepresented and not able to get them returned for refund.

A possible solution may be to have them shipped to a CRS for recertification at sellers expense, and then pick them up directly from the CRS after inspection. These are not boat props.... if/when one sheds a blade in-flight the loss of the airplane is the usual/unfortunate result.

How can a junk-prop appear airworthy?
By being bent excessively, then straightened. (Such as being from a tied-down aircraft, flipped in a storm.) Or by being heated, either purposely for straightening or by being involved in a fire.
It may be fine for a "wall hangar" but not for installation.

[terryg3454]

is there anyone out there with a straight tail, tail wheel 172 that has got a 337 or field approval for the mcauley 1A175DM8042 ?
please let me know or email me at terryguttormson@gmail.com thank you.

[twlareau]

The conundrum:

I want to increase my climb performance without killing my cruising speed. I know that these two performance parameters are at the opposite sides of the performance curve for our somewhat underpowered fixed pitch aircraft.

I currently have a McCaulley 1A170DM7651 (stock climb prop) My typical takeoff's are at 4000-6000' density altitude. My static RPM is 2240 (within limits) I typically cruise at 2600RPM at 7500' density altitude and get about 118 MPH or 135 TAS.
When I climb at about 85 IAS the RPM drops to about 2300 with a rate of climb in the 300' per minute range. It kind of feels like I'm driving up hill in fourth gear.

I have been thinking of going with a 1A175DM8042 or 8043 (the 8043 is not in stock 60-90 days to make) I contacted McCaulley today and they could not give me any hard numbers on performance that I could expect. The only info they could give is that for every inch in length gained I could expect 20 RPM less (static) and for every inch decreased in pitch I could expect a 30RPM increase. They also suggested that I contact the STC holder. (Kenmore Air) I contacted them as well and they said they sell the STC but do not support it anymore and had no performance data. The prices that I have been able to find on a new 1A175DM8042 are $3600.00-$3700.00 + the STC $200.00

I called Rocky Mountain Propellers in Erie Colorado. (about an hour from my house) I talked to Ken (owner) and asked him what he would do. He asked me when my propeller was overhauled. (1985) He said that he could overhaul it and re-pitch it to a 48 or 49 for $520.00. He said I would probable loose 5 or 10MPH and gain about 200FPM in the climb.

What do you guys think? I need to get over those big rocks to the west with some comfort but do not want to start looking at my new Cessna170 calender as my DME. I do love the look of the long prop but is the performance gain worth almost $4G's? on the other hand If I spend over $500 on an overhaul and re-pitch and not gain much but a lighter wallet I will be disappointed.

I know the guys in Alaska love the 8042 and have posted some of their results but does anyone have results at higher density altitudes?

Thanks,
Thad

[bigrenna]

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[GAHorn]

If you want to increase your climb perf but not affect your cruise, there is a simple solution...

Buy a 180.

All it takes is a lot more money for purchase, maintenance, and operating costs & insurance. (You're going to spend a LOT more dollars for the next 10% in performance-improvement over the standard C-170.)

For the investment dollars, the 170 is one of the very BEST airplanes available, suitable for most family operations.

[Bruce Fenstermacher]

Thad,

Look at the TCDS. It has static limits for the approved props. Remember you have a land plane. I've underlined the land plane limits.

(a) McCauley 1A170 33lb. (-39) (-39) (-39)
Static r.p.m. at max. permissible throttle setting:
Landplane: Not over 2330, not under 2230
Seaplane (Models 170A and 170B): Not
over 2525, not under 2300.
No additional tolerance permitted.
Diameter: Not over 76 in., not under 74.5 in.

(f) McCauley 1C172/MDM 30 lb. (-39) (-39) (-39)
Static r.p.m. at maximum permissible throttle setting:
Landplane: Not over 2350, not under 2250
Seaplane: (Models 170A and 170B): Not over
2525, not under 2300
Diameter: Not over 76 in., not under 74.5 in.
No additional tolerance permitted.

What this means is that when you lock your brakes (and maybe tie the tail to the ground) in a takeoff environment (not with your hanger immediately behind the aircraft) the maximum RPM you can make at full throttle is 2330 with the McCauley 1A170.

Chances are you will not be able to install a 48 or 49 pitch prop and remain in the legal limits. But we won't know until you test your plane. So go out to a clear spot, with a electronic tach in hand, chock the wheels, hold the brakes and run that engine up and see what that electronic tach says.

Then using the formulas McCauley gave you figure out how much more you could flatten your prop.

Notice the McCauley 1C172/MDM allows an additional 20 rpm. This does not mean you can pitch it flatter. This prop has a better blade profile with less drag and so it spins faster for the same pitch. What it means is you can have the same climb performance with slightly better cruise. This is why it is a desirable prop.

[kbbell]

Maxwell Aircraft in Crystal, MN converted a DM7653 to an MDM7649 seaplane/climb prop for me, years ago. It was a noticeable improvement off the water [ I believe that I was over 2500rpm], but still allowed me to cruise at 102-105mph. I eventually went with an 80x40 with the Kenmore STC, only because I had to get off a small lake and over a 200'+ shoreline, my cruise dropped to 92-95mph. On wheels, I think a 7648 or 7649 would be a good compromise. A $500 charge seems reasonable, mine was $250 15 years ago.