I'm sure this has been discussed before, but can someone give me the REAL numbers difference in using a Lyc 180 vs. the Continental C-145? Do all the conversions use a controllable pitch prop, or is there any with a fixed pitch? Not convinced it's the way to go, but would like to know the advantages in the numbers.
Thanks, Dan
Lycoming 180 conversion
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Lycoming 180 conversion
1954 170B N170L - just about ready to fly!
1950 170A N9910A - just unloaded in the hangar
Cub and Navion Rangemaster still in pieces
1950 170A N9910A - just unloaded in the hangar
Cub and Navion Rangemaster still in pieces
As far as I know there are no officially published/approved "numbers" that represent performance matters for this conversion. The conversion merely claims to beat the original installation.
Takeoff/climb performance is dramatically improved. Cruise speeds are less impressive due to the old drag issues. (Drag increases as the square of velocity, so the increase in horsepower does not increase speed linearly. However it does increase fuel burn, and an increase in fuel capacity is usually considered desireable and a problem.)
Yes there are both fixed and constant-speed prop installations.
Takeoff/climb performance is dramatically improved. Cruise speeds are less impressive due to the old drag issues. (Drag increases as the square of velocity, so the increase in horsepower does not increase speed linearly. However it does increase fuel burn, and an increase in fuel capacity is usually considered desireable and a problem.)
Yes there are both fixed and constant-speed prop installations.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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cessna170bdriver
- Posts: 4068
- Joined: Mon Apr 22, 2002 5:13 pm
If you use the 180 hp only for takeoff and climb you can operate just about as economically as a 145. I flew from Idaho to Anchorage in 2000 along side two O-360-converted 170's and they didn't use any more fuel than I did. However, not everyone would be disciplined enough to fly a Lyc like that.gahorn wrote:Takeoff/climb performance is dramatically improved. Cruise speeds are less impressive due to the old drag issues. (Drag increases as the square of velocity, so the increase in horsepower does not increase speed linearly. However it does increase fuel burn, and an increase in fuel capacity is usually considered desireable and a problem.)
Miles
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
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Jr.CubBuilder
- Posts: 517
- Joined: Thu Aug 12, 2004 10:33 pm
I did the conversion to mine a year ago. As they said above the takeoff and climb are dramatically improved, exact numbers I don't have rather I use the book numbers from my old owners manual and know that I have a very good margin of safety when it comes to clearing an obstacle at the end of the runway. Performance is better at higher altitudes because it's got another sixty cubic inches of displacement, and the constant speed prop really helps by giving the best of both worlds, redline on climbout and good bite up high.
Cruise speed is the same and fuel burn is the same until you start wanting to go faster, it takes a lot more ponies to go a little faster and you have to feed the ponies. If you are considering the conversion I would offer that it's a waste of money if what you want is speed. I wanted better shortfield and high density altitude performance and I'm quite happy with the result, but if you want to get from point A to point B faster you would be better off getting another plane.
You can do the conversion with a fixed pitch prop and it will keep approximately 20lbs off the nose. The Lyc O360 is about 20lbs lighter than the C145/O300, so the total weight with the constant speed is pretty close to the same, but the center mass of that weight (motor prop combo) moves forward quite a bit. Because of that and the cost of the governor I would think about using a fixed pitch if I were to do it again.
Cruise speed is the same and fuel burn is the same until you start wanting to go faster, it takes a lot more ponies to go a little faster and you have to feed the ponies. If you are considering the conversion I would offer that it's a waste of money if what you want is speed. I wanted better shortfield and high density altitude performance and I'm quite happy with the result, but if you want to get from point A to point B faster you would be better off getting another plane.
You can do the conversion with a fixed pitch prop and it will keep approximately 20lbs off the nose. The Lyc O360 is about 20lbs lighter than the C145/O300, so the total weight with the constant speed is pretty close to the same, but the center mass of that weight (motor prop combo) moves forward quite a bit. Because of that and the cost of the governor I would think about using a fixed pitch if I were to do it again.
I drive a 1960 172A converted to tailwheel with the Avcon conversion and a McCaully 7656 fixed pitch prop. My fuselage is basically the same as the 170B except for the swept back tail. I have gear legs similar to 180 legs, and 8.50's on the mains. My wings were made from 170B cores but have had the Horton STOL added with the cambered leading edge cuff and stall fences. I also have 30 gal extended fuel in the wings for 72 total, 67 usable. The bird has only been in the air since early last May so I am still learning about it. I don't have many of the figures you are looking for but have made several observations. The added power is great, especially if you suddenly have to do a go around at extremely short final and flaps 40. You just ignore the flaps and do it.....the power is there with no problem. In fact you can steadily climb with flaps 40 if needed. I had a cg prob that made it difficult to land as it exagerated the forward weight. A contributing factor is that I am only set up right now as a two place with no back seat or hat rack....just an open area.
Anyway, the first thing I noticed was the quickness and power on short field takeoff's using 20 flaps.....unbelievable how quickly it wants to fly and how steady it comes off the ground just starting to indicate a bit over 40!....and rock, solid stable through ground effect. I have found the climb and responsiveness wonderful. At cruise it indicates between 130-135 at 2500 rpm and between 115 - 120 at 2300 rpm. I haven't flown it long enough to be able to realistically calculate true fuel burn but have noticed that it doesn't seem excessive (I'm running a 1500 hour engine). All in all, I am happy with it but am still learning.
As for the forward cg with a cs prop, I would hate to try to fly my bird with that combo set up as a two seater......to solve the cg prob, we had to add 80 lbs of removable ballast in the baggage area to get the cg back where it belonged in the cg envelope. And this was after we got rid of the extra weight of a generator and went with a B&C alternator. I can't imagine how bad it would have been with an additional 20 lbs out on that long arm in front of the datum. Anyway, these are a few of my observations.
Finally, would I do it again? Probably. If I had to have more speed, I would probably sell my poorman's 180 and just buy a real 180......don't think I will though.
Anyway, the first thing I noticed was the quickness and power on short field takeoff's using 20 flaps.....unbelievable how quickly it wants to fly and how steady it comes off the ground just starting to indicate a bit over 40!....and rock, solid stable through ground effect. I have found the climb and responsiveness wonderful. At cruise it indicates between 130-135 at 2500 rpm and between 115 - 120 at 2300 rpm. I haven't flown it long enough to be able to realistically calculate true fuel burn but have noticed that it doesn't seem excessive (I'm running a 1500 hour engine). All in all, I am happy with it but am still learning.
As for the forward cg with a cs prop, I would hate to try to fly my bird with that combo set up as a two seater......to solve the cg prob, we had to add 80 lbs of removable ballast in the baggage area to get the cg back where it belonged in the cg envelope. And this was after we got rid of the extra weight of a generator and went with a B&C alternator. I can't imagine how bad it would have been with an additional 20 lbs out on that long arm in front of the datum. Anyway, these are a few of my observations.
Finally, would I do it again? Probably. If I had to have more speed, I would probably sell my poorman's 180 and just buy a real 180......don't think I will though.
1966 C182J
1960 C172A Tail Wheel
1960 C172A Tail Wheel
I've got an 0-320 with a C/S prop and I fly with the back seat removed. Although I moved the battery aft, the C of G is well within limits and the plane handles beautifully (well most of the time when I 3Pt but not so good when I wheel land) (I've been trying to wheel land since the post on wheelies made it sound easy). I'm just wondering how that much weight found its way forward on your plane?
If you're really in the market for an engine upgrade in your C-170, keep in mind that four cylinder engines have only two thirds as many firing impulses as six cylinder engines and there is a considerable difference in vibration.
For really smooth operation, think Continental IO-360. It will fit right inside of the cowling, thus no change in aerodynamic drag configuration.
It is also has a thirty horsepower edge on the "other" one.
The only bite is that they're almost impossible to find other than new.
A stock engined C-170 will average about fifteen miles per gallon, on XC,
at about 120 MPH TAS.
An IO-360 Continental powered one will do about twenty MPG at about
150 MPH TAS.
For performance confirmation, check with TIC170A member #2656
For really smooth operation, think Continental IO-360. It will fit right inside of the cowling, thus no change in aerodynamic drag configuration.
It is also has a thirty horsepower edge on the "other" one.
The only bite is that they're almost impossible to find other than new.
A stock engined C-170 will average about fifteen miles per gallon, on XC,
at about 120 MPH TAS.
An IO-360 Continental powered one will do about twenty MPG at about
150 MPH TAS.
For performance confirmation, check with TIC170A member #2656
BL
I wish I knew how that cg got so far forward too. My IA and I have been unable to figure why there was so much difference from the W&B calculations (which were done with full oil and no fuel on the scales in level position) and subsequently with people and fuel. By our calculations, it was consistently between the forwardmost position line on the cg envelope or 1.5 to 2.5 inches forward of that. Things done that have moved the cg back is the B&C Alternator in place of the generator, the Odyssey dry cell battery on the firewall instead of a Gill 25, and the ballast. I'm really surprised that those 4 cylinders hanging so far forward had that much effect. The Avcon Conversion allows me to go with a CS prop but, if I did that, I would probably have to go back to a conventional battery and put it in the tail at the very least. That means more weight and less payload. When you have the extra fuel I have, you have to be very careful and be sure of W&B.
How did the forward cg make it handle before the ballast? Very interesting, alarming, and squirrelly.
When you went to flair on a 3 pt, you would almost have to make it balloon to get much of a reaction in slowing your descent, then if you froze until it stopped ballooning and continued your pull when it started to settle again (i.e, by the book) it would stop settling, hang where it was until it got close enough to a stall to make it drop in......frequently starting to porpoise at that point. Because of this, I began to get somewhat scared of it. After we identified the problem and got the ballast installed, I spent about 4 hours with an instructor as safety pilot until we found out what would happen.....tamed it down quite a bit, but you still have to watch it on 3 pts......with power at idle, it takes just a little elevator until about the time it is ready to touch down. As soon as it touches, pull all the way back in one smooth movement and it's docile. As for wheel landings, I come in at between 1400 and 1500 rpm with flaps 40. Just before it touches, I pull back a very small bit and add a touch more power until it touches down......seems to make the wheel landings a lot smoother.....as soon as it touches, I cut power and keep the tail up until it wants to fall. Then let it fall and full back elevator until at bicycle riding speed to avoid any chance of a ground loop.
Not the technique a lot of folks use, but it works with this bird. Another problem is the swept back tail and rudder authority landing (or lack thereof). Thinking about putting a square tail on it. The touchiness of landing it is the only thing I don't like about it. It's been an interesting learning curve for sure.
How did the forward cg make it handle before the ballast? Very interesting, alarming, and squirrelly.
When you went to flair on a 3 pt, you would almost have to make it balloon to get much of a reaction in slowing your descent, then if you froze until it stopped ballooning and continued your pull when it started to settle again (i.e, by the book) it would stop settling, hang where it was until it got close enough to a stall to make it drop in......frequently starting to porpoise at that point. Because of this, I began to get somewhat scared of it. After we identified the problem and got the ballast installed, I spent about 4 hours with an instructor as safety pilot until we found out what would happen.....tamed it down quite a bit, but you still have to watch it on 3 pts......with power at idle, it takes just a little elevator until about the time it is ready to touch down. As soon as it touches, pull all the way back in one smooth movement and it's docile. As for wheel landings, I come in at between 1400 and 1500 rpm with flaps 40. Just before it touches, I pull back a very small bit and add a touch more power until it touches down......seems to make the wheel landings a lot smoother.....as soon as it touches, I cut power and keep the tail up until it wants to fall. Then let it fall and full back elevator until at bicycle riding speed to avoid any chance of a ground loop.
Not the technique a lot of folks use, but it works with this bird. Another problem is the swept back tail and rudder authority landing (or lack thereof). Thinking about putting a square tail on it. The touchiness of landing it is the only thing I don't like about it. It's been an interesting learning curve for sure.
What is your empty weight on your plane? Some tailwheel converted planes are very heavy when empty. For instance I flew a tailwheel converted 175 with a 180hp and constant speed prop but it performed horribly, I discovered its empty weight was around 1650 lbs I have flown several 180hp 170B's with constant speed props and none of them are out of there forward CG limit empty. I was very concerned about the CG of mine with the IO-360 and constant speed prop, but when I load my plane to its most forward CG configuration it is just slightly forward of its limit. However I always carry survival gear so I just throw that back in the extended baggage and that cures it.
For a three point landing your elevator should be all the way back in your lap before your wheels touch. You should run out of elevator just before your wheels touch.
If you are within your CG limits it should not be squirly. Makes me wonder if your mechanic properly aligned your wheels when he did the conversion. Good luck.
Shawn
For a three point landing your elevator should be all the way back in your lap before your wheels touch. You should run out of elevator just before your wheels touch.
If you are within your CG limits it should not be squirly. Makes me wonder if your mechanic properly aligned your wheels when he did the conversion. Good luck.
Shawn
Shawn, the empty weight on the W&B is 1329.7 (that's with 7 qts of oil and totally empty on fuel) with a gross of 2200. I just checked my computer for the last calc I did the last time I flew it and.....with 40 gals on board and two ppl in the front seat at 480 (big guys) the total weight was 2049.7 with moment of 80997.5 and a cg of 39.516 which puts it barely behind the forward line of the cg envelope by about 1/4 inch. Adding the 80 lbs at baggage changes the weight to 2129.7 with a moment of 88597.5 which results in a cg of 41.600 which places it about 1 1/2 inches behind the forwardmost cg for that weight in a comfortable position in the normal category.
I don't think there is any prob with the alignment. It tracks quite well. As far as rigging goes, we did have a problem with a left roll due to a heavier left wing and crooked flap trailing edge that is now corrected, but I don't like where the wings are set.
You fly to Merrill in Anchorage very often Shawn? If you do, let me know and we can meet for a cup of coffee near the field sometime.
BL, as you can see from these calcs, I'm dealing with the cg and cg envelope rather than the loading index.
I don't think there is any prob with the alignment. It tracks quite well. As far as rigging goes, we did have a problem with a left roll due to a heavier left wing and crooked flap trailing edge that is now corrected, but I don't like where the wings are set.
You fly to Merrill in Anchorage very often Shawn? If you do, let me know and we can meet for a cup of coffee near the field sometime.
BL, as you can see from these calcs, I'm dealing with the cg and cg envelope rather than the loading index.
Wow is that a scaled weight or a calculated weight. That is very light. My plane does not start feeling weird unless my CG is less than 36. I routinly fly mine with the CG around 36.5 at 2000 lbs and it flies perfectly normal. I realize for that weight I am a little over 4" forward of my CG limit. I wonder if a contributing factor to the differences in the handling of our two airplanes at comparable CG's is just the difference in our tails. I have never flown mine outside the aft limit but I have flown it withen about 1/4" of the aft limit and it was very stable and doscel.
Occasionally I do get up there. That would be fun to grab a cup of coffee.
Shawn
Occasionally I do get up there. That would be fun to grab a cup of coffee.
Shawn
I just did a W&B calculation on my O-300 powered 170 with 480 pounds of people in the front seat and no baggage. With full fuel, the C.G. is forward of the limit. With empty tanks it's barely legal.
If the front seat occupants weigh 170 lbs each, the C.G. without baggage is forward, but comfortably within the range limits.
I think there are many aircraft with this loading characteristic. I've flown others where you have to add some weight aft in order to carry two large people in the front seat and nobody in the rear seat.
Best Regards,
John
If the front seat occupants weigh 170 lbs each, the C.G. without baggage is forward, but comfortably within the range limits.
I think there are many aircraft with this loading characteristic. I've flown others where you have to add some weight aft in order to carry two large people in the front seat and nobody in the rear seat.
Best Regards,
John
John Renwick
Minneapolis, MN
Former owner, '55 C-170B, N4401B
'42 J-3 Cub, N62088
'50 Swift GC-1B, N2431B, Oshkosh 2009 Outstanding Swift Award, 2016 Best Continuously Maintained Swift
Minneapolis, MN
Former owner, '55 C-170B, N4401B
'42 J-3 Cub, N62088
'50 Swift GC-1B, N2431B, Oshkosh 2009 Outstanding Swift Award, 2016 Best Continuously Maintained Swift
Shawn,
The weight was on certified scales when Rod Miland of RM Aircraft Services did the official W&B last April. We hoisted it up in level flight attitude with his digital electronic scale system under it and weighed it with 7 qts of oil and absolutely zero fuel to get the static weight. Rod does W&B and prop balancing here in Anchorage and has probably done some in the Soldotna area. He is an IA and my IA recommended him. I have to assume that they knew what they were doing. The wierd thing is the weight difference between the wings. The left wing was noticeably heavier than the right wing. The original empty weight was 1340 but I lost 10.3 when we converted from a 60 amp gen to a 40 amp B&C Alternator and regulator. Naturally, the cg range and evvelope are right off the TCDS.
Computations using people weights of 170 are nice in theory but really useless to me as they don't reflect reality. I have to be dilligent about computing the weight as I am a big guy weighing 300 at 6'4". Even so, with me in it solo and the full fuel load of 67 usable, I am now still within the range at 2141.7 lbs with a moment of 91333.5 and a cg of 42.645. Minimal survival gear would put me right on the weight limit including the Northern Companion and engine blanket. This summer I plan to have the ballast in it in the form of two 5 gal plastic water jugs strapped down in the aft baggage area. That makes the ballast disposable. Can't do that in the winter as the water gets too stiff on the tie down to pour very well.....lol. Right now, I'm planning on talking to my IA about putting 15 to 20 lbs just forward of the rear bulkhead in front of the elevator at station 240. That would result in only a 20 lb gain on empty weight, but would manipulate the cg to respond very similar to keep it in the envelope range.
As for your comment about the tail, I have been up with several experienced tailwheel instructors up here. Both have stated I should stay out of direct crosswinds of over 10 kts because of rudder authority. I've heard both sides of the argument about the square tail vs. the slant tail......sure wish I had a square tail right now. The bird flies the same as any other 170 or 172 except in that necessary window of landings. The rudder just isn't as effective as it should be. My IA thinks vg's would solve the prob but I would have to buy the entire kit. My wings fly slow enough as it is now..right now, I don't know what speed it stalls in a straight attitude because the airspeed indicator has been dead on zero for a bit before it will finally break )...don't need to slow them down any more....just need more rudder authority. This summer I'll probably go up and stall it using my gps to figure out where it stalls in a straight attitude. My IA, who has flown and stalled it, is betting it's between 38 and 35!!!!
pat
The weight was on certified scales when Rod Miland of RM Aircraft Services did the official W&B last April. We hoisted it up in level flight attitude with his digital electronic scale system under it and weighed it with 7 qts of oil and absolutely zero fuel to get the static weight. Rod does W&B and prop balancing here in Anchorage and has probably done some in the Soldotna area. He is an IA and my IA recommended him. I have to assume that they knew what they were doing. The wierd thing is the weight difference between the wings. The left wing was noticeably heavier than the right wing. The original empty weight was 1340 but I lost 10.3 when we converted from a 60 amp gen to a 40 amp B&C Alternator and regulator. Naturally, the cg range and evvelope are right off the TCDS.
Computations using people weights of 170 are nice in theory but really useless to me as they don't reflect reality. I have to be dilligent about computing the weight as I am a big guy weighing 300 at 6'4". Even so, with me in it solo and the full fuel load of 67 usable, I am now still within the range at 2141.7 lbs with a moment of 91333.5 and a cg of 42.645. Minimal survival gear would put me right on the weight limit including the Northern Companion and engine blanket. This summer I plan to have the ballast in it in the form of two 5 gal plastic water jugs strapped down in the aft baggage area. That makes the ballast disposable. Can't do that in the winter as the water gets too stiff on the tie down to pour very well.....lol. Right now, I'm planning on talking to my IA about putting 15 to 20 lbs just forward of the rear bulkhead in front of the elevator at station 240. That would result in only a 20 lb gain on empty weight, but would manipulate the cg to respond very similar to keep it in the envelope range.
As for your comment about the tail, I have been up with several experienced tailwheel instructors up here. Both have stated I should stay out of direct crosswinds of over 10 kts because of rudder authority. I've heard both sides of the argument about the square tail vs. the slant tail......sure wish I had a square tail right now. The bird flies the same as any other 170 or 172 except in that necessary window of landings. The rudder just isn't as effective as it should be. My IA thinks vg's would solve the prob but I would have to buy the entire kit. My wings fly slow enough as it is now..right now, I don't know what speed it stalls in a straight attitude because the airspeed indicator has been dead on zero for a bit before it will finally break )...don't need to slow them down any more....just need more rudder authority. This summer I'll probably go up and stall it using my gps to figure out where it stalls in a straight attitude. My IA, who has flown and stalled it, is betting it's between 38 and 35!!!!
pat