GPS derived average ground speed (upwind, downwind, xwind) over several hundred hours with my 80-42 prop at 2450 RPM and approx sea level to 3000 MSL has worked out real close to 100mph. This is with 8:00x6 tires, NO floats! I thought that I would be swapping my old DM76-53 on and off with the 80-42 depending on the mission but I'll tell you that you get "hooked" on the performance of takeoff and climb and am willing to sacrifice the cruise. But flying into a 20 knot headwind on a long x-country makes for a very long day.
My next trick is going to be to bolt on my MDM 76-55 prop and see what the other end of the spectrum is like.
Bruce
Cessna 170 on floats
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
I just got back from a 20+ hour cross country trip, flight of two 170B's, Mine with a 7655 prop, the other with a 7653. Both aircraft are standard aircraft with wheel fairings. Although I was more heavily laden by about 150 lbs, (pilot with the "successful look", wife's first long x-country, packed for 2 or 3 changes of clothes daily plus Ismarelda Marco's shoe collection), here's what I found.
Actual ground-runs on takeoff, no discernable difference.
Climb performance, 7653 vastly superior. (I was at 7500 climbing to 10,500, he was at 5,500 climbing to 10,500. He beat me to 10,500 by 15 minutes! He was out of 9,500 before I got that high. Both of us climbing at 80 mph IAS.
Cruise performance, I ran full throttle 2450 rpm at 9,500 with 118 TAS. He ran 2500 rpm, full throttle, with 116 TAS. He burned 1.5 gph less per hour the entire trip. (This may be personal leaning techniques/preferences. I deliberately run on the rich side.) But the conclusion I came to was that even tho' pulling 50 rpm less than the standard prop, I pull the same manifold pressure. This equals higher percentage of power setting. Therefore, that would help explain the higher fuel burn and 2 mph greater speed, if all other things were equal.
Anyone with a C or D engine, wanting a 6-bolt EM7655 prop, ...I am wanting a EM7653.
Actual ground-runs on takeoff, no discernable difference.
Climb performance, 7653 vastly superior. (I was at 7500 climbing to 10,500, he was at 5,500 climbing to 10,500. He beat me to 10,500 by 15 minutes! He was out of 9,500 before I got that high. Both of us climbing at 80 mph IAS.
Cruise performance, I ran full throttle 2450 rpm at 9,500 with 118 TAS. He ran 2500 rpm, full throttle, with 116 TAS. He burned 1.5 gph less per hour the entire trip. (This may be personal leaning techniques/preferences. I deliberately run on the rich side.) But the conclusion I came to was that even tho' pulling 50 rpm less than the standard prop, I pull the same manifold pressure. This equals higher percentage of power setting. Therefore, that would help explain the higher fuel burn and 2 mph greater speed, if all other things were equal.
Anyone with a C or D engine, wanting a 6-bolt EM7655 prop, ...I am wanting a EM7653.
I'm picturing our race to include a climb to 12,000 feet, 5 mile level high cruise, desend to spot landing 
Yes, Joe. I knew that'd elicit a response from you. 
I don't mind saying it. That was on the way to Las Vegas across the desert with density altitudes running 14K approx. It reminded me that the 170 is not a sloppy-pilot's airplane. Despite it's gentle handling down low, and it's simple systems, it's a challenge for any pilot to fly well. I think that's one reason it has such wide appeal.
I don't mind saying it. That was on the way to Las Vegas across the desert with density altitudes running 14K approx. It reminded me that the 170 is not a sloppy-pilot's airplane. Despite it's gentle handling down low, and it's simple systems, it's a challenge for any pilot to fly well. I think that's one reason it has such wide appeal.
Tim
Woh! those numbers are pretty low...not much room for errors there as unless I am wrong we are looking at only 25 mph between crusing and stall speed (on that particular day anyhow) are we? Well like I said earlier speed is not really an issue with me. Getting off the water is obviously more important but once I am airborne I am happy...
Thanks for sharing the figures Tim (and others). It really helps me to get my mind around the different 170 combos.
Eric
The tv show you are referring to is very popular up here even though it was filmed in one of the northern province. It gives you a good idea of the people and some the landscape of the NWT.
I have been everywhere in the NWT and it has been a while since I have seen a cessna 170 along the Liard valley. "Liard Trapper" might be from Northern British Columbia where this river takes its source.
Thanks for the input everyone. Those of you flying at 10,000 +, well you won't see me way up there with my Citabria. Probably run out of gas before I get this high!
Cheers
Bruno
Ft Smith, NT
Woh! those numbers are pretty low...not much room for errors there as unless I am wrong we are looking at only 25 mph between crusing and stall speed (on that particular day anyhow) are we? Well like I said earlier speed is not really an issue with me. Getting off the water is obviously more important but once I am airborne I am happy...
Thanks for sharing the figures Tim (and others). It really helps me to get my mind around the different 170 combos.
Eric
The tv show you are referring to is very popular up here even though it was filmed in one of the northern province. It gives you a good idea of the people and some the landscape of the NWT.
I have been everywhere in the NWT and it has been a while since I have seen a cessna 170 along the Liard valley. "Liard Trapper" might be from Northern British Columbia where this river takes its source.
Thanks for the input everyone. Those of you flying at 10,000 +, well you won't see me way up there with my Citabria. Probably run out of gas before I get this high!
Cheers
Bruno
Ft Smith, NT
I have operated a 170B on floats with the C-145 engine for over 700 hours here in Yellowknife, NT. Why don't you give me a call, Bruno and perhaps you can fly up here and see for yourself how it performs. It's a two place airplane on floats for sure and on a hot day at gross and on glassy water you often need a bit of technique to get it off the water. I think it has made me a better pilot. I love the airplane. Would I like a bit more power? Sure, but I'd like a turbo-beaver too. Feel free to contact me off line or phone me. I'm in the book.
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zero.one.victor
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- Joined: Tue Apr 23, 2002 12:11 am
George,instead of swapping your 7655 for a 7653,why not just have yours repitched? The prop shops in this area charge around $125-150 for this.
What is the difference between a DM and an EM prop? Is it the 6 bolt pattern versus 8 bolt? Mine's a DM,8 bolt C-145 crank flange.
Oh,I would say the best prop is a 7651 for all-around use. I see just about 113 or so with 800 tires,at low altitude (3000' MSL & below).Good enough cruise speed for trips yet still good out of the hole. I'd rather be 5 minutes late to my destination than 5 feet too low at the treeline at the end of the airstrip!
Eric
What is the difference between a DM and an EM prop? Is it the 6 bolt pattern versus 8 bolt? Mine's a DM,8 bolt C-145 crank flange.
Oh,I would say the best prop is a 7651 for all-around use. I see just about 113 or so with 800 tires,at low altitude (3000' MSL & below).Good enough cruise speed for trips yet still good out of the hole. I'd rather be 5 minutes late to my destination than 5 feet too low at the treeline at the end of the airstrip!
Eric
(See my response under "Comparing Props") Essentially the DM is thicker/wider/heavier than the MDM/EM series. The EM is a 6-bolt, the others are 8-bolt. Having my prop repitched is my second choice. I've had a prop repitched once before, and I was disappointed in the "waviness" that resulted in it's trailing edge.zero.one.victor wrote:George,instead of swapping your 7655 for a 7653,why not just have yours repitched? The prop shops in this area charge around $125-150 for this.
What is the difference between a DM and an EM prop? Is it the 6 bolt pattern versus 8 bolt? Mine's a DM,8 bolt C-145 crank flange.
Oh,I would say the best prop is a 7651 for all-around use. I see just about 113 or so with 800 tires,at low altitude (3000' MSL & below).Good enough cruise speed for trips yet still good out of the hole. I'd rather be 5 minutes late to my destination than 5 feet too low at the treeline at the end of the airstrip!
Eric
Cessna 170 on floats
zero.one.victor
Ya, I'm still around. I too, enjoy North of Sixty. I can associate with the small town setting. I am in a area where we have small settlments with the air strips in the middle of towns. To name a few, 100 Mile House, Toad River, Ft. Ware, Edson & Ft. Liard.
Bruno,
I own a trapline, in BC, on the north side of the Liard River. (Drainage basin of the Grayling River).
My 170B is on wheels. Personally I wouldn't put my bird on floats as long as it has the current 0-300 engine. I have been trying to improve its landing and takeoff abilities without spending a wheelbarrow of money.
If I could afford it I would buy a new 8042 prop (around $6000 Canadian), as I find it is almost impossible to find a used one.
I have a Areo-Matic prop which I will try some time this summer. I have just recieved it back from the prop shop.
I will also try a set of drop tips to see if that helps.
Presently I opporate my plane in a stripped down configuration. Pilots seat only, 800 rubber, no paint and dual puck cleaveland brakes. In this configuration I can opporate out of one way 800 ft dirt and grass strips to a elevation of 3600 ft , as long as the wind is in the right direction. I also make sure there is no trees in the direction I'm taking off or landing from,and I always lean the mixture before takeoff.
Good Luck
Trapper
Ya, I'm still around. I too, enjoy North of Sixty. I can associate with the small town setting. I am in a area where we have small settlments with the air strips in the middle of towns. To name a few, 100 Mile House, Toad River, Ft. Ware, Edson & Ft. Liard.
Bruno,
I own a trapline, in BC, on the north side of the Liard River. (Drainage basin of the Grayling River).
My 170B is on wheels. Personally I wouldn't put my bird on floats as long as it has the current 0-300 engine. I have been trying to improve its landing and takeoff abilities without spending a wheelbarrow of money.
If I could afford it I would buy a new 8042 prop (around $6000 Canadian), as I find it is almost impossible to find a used one.
I have a Areo-Matic prop which I will try some time this summer. I have just recieved it back from the prop shop.
I will also try a set of drop tips to see if that helps.
Presently I opporate my plane in a stripped down configuration. Pilots seat only, 800 rubber, no paint and dual puck cleaveland brakes. In this configuration I can opporate out of one way 800 ft dirt and grass strips to a elevation of 3600 ft , as long as the wind is in the right direction. I also make sure there is no trees in the direction I'm taking off or landing from,and I always lean the mixture before takeoff.
Good Luck
Trapper
IA175DM props
I have an IA175DM 8046 on my 53 with 8:oo tires and regularly cruise at 105 sm/hr at 2500rpm which the GPS confirms. The different speeds which different pilots report may be due to how well the various props are pitched. If you get McCaully data on pitch you will see that a precise angle is specified at every station from hub to tip at three inch intervals. If those stations vary from spec plus and minus at random then the prop becomes very inefficient since some stations try to advance faster than others and they are all connected. My prop was repitched as a new prop from the factory because the factory doesn't sell a 8046 unless you want to wait for ever. After being carefully pitched and balanced it runs very smoothly and has tremendous pull. After flying with a 7653 the difference pulling out of a muddy tie down is dramatic.
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
Eric
The Canadian shield (Precambrian shield) is a vast expanse of exposed bedrock that covers most of northern Canada. It goes from the northern tip of Great Bear Lake (was just there a few days ago for work) in the NWT all the way to NewFoundland in eastern Canada.
Contrary to most of Southern Canada and USA, the main "basement" layer has no sedimentary rock on its surface..just hard solid bedrock covered by the boreal forest (black and white spruce, jackpine and birch being the main trees).
Those are known to be some of the oldest rocks on earth as its deformation and erosion process started more than 1 billion years ago which has shaped the landscape in such a way as there are hardly any mountains or major change in elevation left...
One of its main feature is that the impact of the last glaciation has left behind thousands of prestine lakes.
All in all perfect for float flying...lots of lakes, lots of fish, sparsely populated, plenty of room to take off, etc.
Fort Smith where I live is located just 30 miles from the western edge of the precambrian shield hence my reference to it in an earlier note.
In a nutshell...
Cheers
Bruno
The Canadian shield (Precambrian shield) is a vast expanse of exposed bedrock that covers most of northern Canada. It goes from the northern tip of Great Bear Lake (was just there a few days ago for work) in the NWT all the way to NewFoundland in eastern Canada.
Contrary to most of Southern Canada and USA, the main "basement" layer has no sedimentary rock on its surface..just hard solid bedrock covered by the boreal forest (black and white spruce, jackpine and birch being the main trees).
Those are known to be some of the oldest rocks on earth as its deformation and erosion process started more than 1 billion years ago which has shaped the landscape in such a way as there are hardly any mountains or major change in elevation left...
One of its main feature is that the impact of the last glaciation has left behind thousands of prestine lakes.
All in all perfect for float flying...lots of lakes, lots of fish, sparsely populated, plenty of room to take off, etc.
Fort Smith where I live is located just 30 miles from the western edge of the precambrian shield hence my reference to it in an earlier note.
In a nutshell...
Cheers
Bruno
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am