I am juggling propeller selection. It's not an iminent decision but I would like to get a handle on it since this could be an expensive purchase which I would like to get right the first time. There are several brands of constant speed propellers out there as well as many fixed pitch propellers. I have the firewall cutout so I will be able to install a constant speed prop if that is my decision. I have a 160 hp 0320 which I guess is about the minimum hp that you would consider a constant speed prop on. Another factor is that I live within about 5 miles of Aero Composites who make a $10,000 constant speed prop that is supposedly the best one out there. Can anybody shed some light on this subject? Cost is definately a factor so unless that expensive constant speed prop is worth the money then I would rather just go for a wooden prop which will be less expensive and less complex.
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Propellers
- Thread starter andrsnj
- Start date
gmcjetpilot
Well Known Member
sensenich
For performance and money I would go with a metal fikxed sensenich. Also your weight & B may benefit with the weight on the nose. My RV-4 had a 150hp and c/s prop and was right on the front cg solo which worked out well when I had a passenger and bags. Also any engine regardless of hp can benefit from a cs prop. My RV-4 with 150 hp was fast.
Keeping weight down is good also and wood is a great material. The draw back is maintenance, scheduled check and re-torque of bolts. Performance of wood blades is going to be just a little less than a metal blades, due to wood needing to be a little thicker. Also Sensenich has got the profile down for the RV's, so picking a prop is pretty sure fire. Another plus is if you want you can repitch the prop for say a later change in the airframe or engine. Wood can be a little hit and miss from the start. One brands pitch is not the same in another brand. Operation in rain is also restricted even with an errosion strip. The plus for wood is light and cheaper. Also if you hit the prop on the ground it is more likely to break and reduce the chance of serious crank or engine damage.
I personally had a c/s hartzell on my RV-4 and the RV-7 I am building now. I love them for cost, performance and very maintenance free (grease once a year). $10,000 composite constant speed props are great but the cost to advantage is not there in my opinion. If cost is important than the metal fixed Sensenich is a great compromise and value. After that a blended airfoil Hartzell is a good value for a c/s prop. For me I am use to C/S prop and have the budget so that is the only way I would go, but I am impressed with Sensenich for a fixed prop, which closed the gap a little in the C/S prop advantage for RV's. C/S will always climbe better and be a little more efficent in cruise (lower RPM for same speed thus less burn and noise).
For performance and money I would go with a metal fikxed sensenich. Also your weight & B may benefit with the weight on the nose. My RV-4 had a 150hp and c/s prop and was right on the front cg solo which worked out well when I had a passenger and bags. Also any engine regardless of hp can benefit from a cs prop. My RV-4 with 150 hp was fast.
Keeping weight down is good also and wood is a great material. The draw back is maintenance, scheduled check and re-torque of bolts. Performance of wood blades is going to be just a little less than a metal blades, due to wood needing to be a little thicker. Also Sensenich has got the profile down for the RV's, so picking a prop is pretty sure fire. Another plus is if you want you can repitch the prop for say a later change in the airframe or engine. Wood can be a little hit and miss from the start. One brands pitch is not the same in another brand. Operation in rain is also restricted even with an errosion strip. The plus for wood is light and cheaper. Also if you hit the prop on the ground it is more likely to break and reduce the chance of serious crank or engine damage.
I personally had a c/s hartzell on my RV-4 and the RV-7 I am building now. I love them for cost, performance and very maintenance free (grease once a year). $10,000 composite constant speed props are great but the cost to advantage is not there in my opinion. If cost is important than the metal fixed Sensenich is a great compromise and value. After that a blended airfoil Hartzell is a good value for a c/s prop. For me I am use to C/S prop and have the budget so that is the only way I would go, but I am impressed with Sensenich for a fixed prop, which closed the gap a little in the C/S prop advantage for RV's. C/S will always climbe better and be a little more efficent in cruise (lower RPM for same speed thus less burn and noise).
Last edited:
Props
I have a Hartzell C/S on the front of my-4 W/ 0360. For short TO & Rate of Climb, & formation it must be a C/S prop. Most of those I fly with have also had speed increases from going to the C/S prop from their fixed. I would go for the Aero prop if within the $$$. It is very smooth & fast. If you are looking for a low cost prop, then it must be a fixed pitch. You will likely go to a C/S prop latter if you start with the fixed & do acro, formation, short strips, & high altitude fields. If those are out of the area of what you do, don't waste the extra $$$ on a C/S. My opinion.
Gary
I have a Hartzell C/S on the front of my-4 W/ 0360. For short TO & Rate of Climb, & formation it must be a C/S prop. Most of those I fly with have also had speed increases from going to the C/S prop from their fixed. I would go for the Aero prop if within the $$$. It is very smooth & fast. If you are looking for a low cost prop, then it must be a fixed pitch. You will likely go to a C/S prop latter if you start with the fixed & do acro, formation, short strips, & high altitude fields. If those are out of the area of what you do, don't waste the extra $$$ on a C/S. My opinion.
Gary
gmcjetpilot
Well Known Member
I don't have a list but..
Many O-320's can use a C/S prop. Some Piper Apache's had two 150hp O-320's with C/S props. My RV-4, also 150hp also had a constant speed prop. Call Lycoming or get the list of certified engines to see which O-320's (low compression) have hollow cranks. I sold my RV-4 many years ago and don't recall all the suffix (A1A, A3A, A3B). Trust me they are out there. Gn38139 said:
Last edited:
TC Data sheets Lycoming
Here is the link to check Lycoming engine data.
http://www.rvproject.com/tcds/
Look close at the weights on 320 /360 and it will change the way you feel about the weight of the 0-360. They weigh less than 10 LBS difference in many cases. I know of a friend who has a 0-320 that is 3 pounds lighter than my 0-360-A1A. The I0-360 has a much greater weight delta though.
Fuel burn per HP is about the same. I fly with several 0-320's and burn the same fuel or less if I run their speed.
Gary
Here is the link to check Lycoming engine data.
http://www.rvproject.com/tcds/
Look close at the weights on 320 /360 and it will change the way you feel about the weight of the 0-360. They weigh less than 10 LBS difference in many cases. I know of a friend who has a 0-320 that is 3 pounds lighter than my 0-360-A1A. The I0-360 has a much greater weight delta though.
Fuel burn per HP is about the same. I fly with several 0-320's and burn the same fuel or less if I run their speed.
Gary
MT or Whirlwind
I would say go with a c/s - they really make the airplane. Its difficult to explain why, but it does. It sjust much more fun. Wood/composite blades are much better from the vibartion view point than metal, so the airplane will be much smoother with an MT, Whirlwind or Aero Comp prop than with a Hartzell. The Hartzell is also cheaper and heavier. MT & Whirlwind are a couple of thousand cheaper than Aero Comp. Does Aero Comp make a prop for O-320s? A Whirlwind 151 or 200RV might do the job?
To answer the question about 150hp engines & c/s, you could either modify an fp 150hp (requires crank case & accessory case machining and more gears), or you could use an electric MT.
Yours, Pete
I would say go with a c/s - they really make the airplane. Its difficult to explain why, but it does. It sjust much more fun. Wood/composite blades are much better from the vibartion view point than metal, so the airplane will be much smoother with an MT, Whirlwind or Aero Comp prop than with a Hartzell. The Hartzell is also cheaper and heavier. MT & Whirlwind are a couple of thousand cheaper than Aero Comp. Does Aero Comp make a prop for O-320s? A Whirlwind 151 or 200RV might do the job?
To answer the question about 150hp engines & c/s, you could either modify an fp 150hp (requires crank case & accessory case machining and more gears), or you could use an electric MT.
Yours, Pete
I originally built my RV6 with 150 HP and a fixed pitch Sensenitch prop, as recommended by VAN's. After about 450 hrs, I overhauled the engine and switched to 160 HP and moved to a CS Hartzell prop. (actually, the change wasn't all that difficult, but you do have to have the correct engine to start with and you'll need a bunch of extra, expensive parts.)
Originally, the RV6 flew great with wonderful climb and great cruise. It was fast for a basic RV6. But,10 extra HP and the CS prop made it a completely different airplane. Climb improved significantly and I picked up about 6 MPH at top end. The climb; however, was the astounding part.
Unless you have the comparison of the before and after, you can't believe how significant the CS prop is to overall performance.
Of course, there is a price, since the prop and governor cost a lot more than the fixed pitch prop.
In building my new RV8, I purchased the CS prop. Hartzell, since the others were too expensive for me.
Originally, the RV6 flew great with wonderful climb and great cruise. It was fast for a basic RV6. But,10 extra HP and the CS prop made it a completely different airplane. Climb improved significantly and I picked up about 6 MPH at top end. The climb; however, was the astounding part.
Unless you have the comparison of the before and after, you can't believe how significant the CS prop is to overall performance.
Of course, there is a price, since the prop and governor cost a lot more than the fixed pitch prop.
In building my new RV8, I purchased the CS prop. Hartzell, since the others were too expensive for me.
My -4 has an O360 and a Sensenich metal prop. First, there are no better people in aviation to do business with than Sensenich. They bent so far over backwards for me that I'm not sure they ever straightened up.
Having said that, I sure wish I had a constant speed prop. If you've never flown behind a constant speed (Cessna 150/172 etc. Piper 140/180 etc.) you won't believe how wonderful an RV with a fixed pitch prop is. But if you are used to pulling the prop back to a nice smooth quiet rpm for cruise, you will be dissapointed screaming around at 2600 rpm or more to keep up with the C/S RV's at 75%. When you push the throttle in on a F/P RV, you will ask yourself why in the world you would need a C/S prop. Then, however, when you get a ride in a C/S RV, you'll say "whoa, baby!" Personally, I wouldn't want a wood prop. The CG possibilities that my metal prop afford me are worth the extra weight and vibes. I don't worry about rain and constantly torqueing the bolts. I'll never know however, the joys of a REALLY light and nimble RV. Bummer, I've heard great things. In the end, it boils down to one thing....
Mission profile.
Also, there are no AD's on my Sensenich! Most likely won't ever be. I like that.
Jeff
Having said that, I sure wish I had a constant speed prop. If you've never flown behind a constant speed (Cessna 150/172 etc. Piper 140/180 etc.) you won't believe how wonderful an RV with a fixed pitch prop is. But if you are used to pulling the prop back to a nice smooth quiet rpm for cruise, you will be dissapointed screaming around at 2600 rpm or more to keep up with the C/S RV's at 75%. When you push the throttle in on a F/P RV, you will ask yourself why in the world you would need a C/S prop. Then, however, when you get a ride in a C/S RV, you'll say "whoa, baby!" Personally, I wouldn't want a wood prop. The CG possibilities that my metal prop afford me are worth the extra weight and vibes. I don't worry about rain and constantly torqueing the bolts. I'll never know however, the joys of a REALLY light and nimble RV. Bummer, I've heard great things. In the end, it boils down to one thing....
Mission profile.
Also, there are no AD's on my Sensenich! Most likely won't ever be. I like that.
Jeff
Roger Moore
Active Member
Props for RV4
Unless you want to waste $10,000 I would not entertain a constant speed prop for the RV4. I have a 3 blade Fred Felix bicambered wood prop on my RV4 and could not be happier. Total cost $1800 climb rate with XP-360 is in excess of 2000 feet per minute and 180 MPH indicated in cruise. In addition to the lower cost of upkeep you have a lighter airplane. If you want the info on the prop just ask. As I said I could not be happier. I wish I could say the same abouts Vans basic design. Reference my broken weldments post. Roger Moore [email protected]
Unless you want to waste $10,000 I would not entertain a constant speed prop for the RV4. I have a 3 blade Fred Felix bicambered wood prop on my RV4 and could not be happier. Total cost $1800 climb rate with XP-360 is in excess of 2000 feet per minute and 180 MPH indicated in cruise. In addition to the lower cost of upkeep you have a lighter airplane. If you want the info on the prop just ask. As I said I could not be happier. I wish I could say the same abouts Vans basic design. Reference my broken weldments post. Roger Moore [email protected]
Last edited:
bigDRathbun
I'm New Here
Props
We just changed out a Warnke for the Sensenich f/p metal. The performance is about the same. It is faster than the wood above 9000 ft. The climb is similar, the vibes are slightly higher.
C/S is great, until you have to maintain it. From a flying standpoint, no question. The cost does not outway the benefit, imo.
We chose the metal specifically for the durability. We operate out of unimproved strips and poorly maintained asphalt ones. Wood doesn't last long.
Dan
We just changed out a Warnke for the Sensenich f/p metal. The performance is about the same. It is faster than the wood above 9000 ft. The climb is similar, the vibes are slightly higher.
C/S is great, until you have to maintain it. From a flying standpoint, no question. The cost does not outway the benefit, imo.
We chose the metal specifically for the durability. We operate out of unimproved strips and poorly maintained asphalt ones. Wood doesn't last long.
Dan
Dave Dollarhide
Active Member
Sensenich FP
I agree with Jeff in that how you use the airplane is a big factor. I fly a long leg 4 with an O360 and a Sensenich FM72. The prop pitch is 83", which would be considered more of a standard prop, vs climb or cruise. My normal wingman flies an O360 RV-7, with the same prop, but pitched at 85. At the same airplane weights, I noticably excell his performance in TO and climb, but he's about 5 to 10 mph faster. At 2700RPM, and SL, I see just short of 190mph indicated and my normal Xcountry cruise is 2450, 170mph at 8gph.
A previous comment in this string noted that a CS prop will out climb a FP. That may be true in some cases, but has not been my experience, after flying with numerous CS RVs and personally flight testing a CS RV-6 and CS RV-8. Even at heavier weights, I normally out climb the CS and excell in TO and go around. They do cruise faster, but no more than 10kts or so. However, when in a dogfight or formation acro., and the CS airplane points his nose downhill is when I start to fall behind. I run out of RPM and have to pull the throttle back, but the CS airplane still has his MP up, the prop at 2,500RPM and a higher speed.
Both CS and FP have their good sides. The FP Sensenich fits with my yank and bank style, but also is a good comprimise for flying A to B. I really like the cost and simplicity aspect. ...not sure why one would want a wood prop on their RV these days, except for the composite types like the CS MT, but then that's around $12,000 and the FP Sensenich is less than $2,000 last I heard.
Either way you go, it's still a hoot.
Dave
I agree with Jeff in that how you use the airplane is a big factor. I fly a long leg 4 with an O360 and a Sensenich FM72. The prop pitch is 83", which would be considered more of a standard prop, vs climb or cruise. My normal wingman flies an O360 RV-7, with the same prop, but pitched at 85. At the same airplane weights, I noticably excell his performance in TO and climb, but he's about 5 to 10 mph faster. At 2700RPM, and SL, I see just short of 190mph indicated and my normal Xcountry cruise is 2450, 170mph at 8gph.
A previous comment in this string noted that a CS prop will out climb a FP. That may be true in some cases, but has not been my experience, after flying with numerous CS RVs and personally flight testing a CS RV-6 and CS RV-8. Even at heavier weights, I normally out climb the CS and excell in TO and go around. They do cruise faster, but no more than 10kts or so. However, when in a dogfight or formation acro., and the CS airplane points his nose downhill is when I start to fall behind. I run out of RPM and have to pull the throttle back, but the CS airplane still has his MP up, the prop at 2,500RPM and a higher speed.
Both CS and FP have their good sides. The FP Sensenich fits with my yank and bank style, but also is a good comprimise for flying A to B. I really like the cost and simplicity aspect. ...not sure why one would want a wood prop on their RV these days, except for the composite types like the CS MT, but then that's around $12,000 and the FP Sensenich is less than $2,000 last I heard.
Either way you go, it's still a hoot.
Dave
Props for RV4
I'm extremely happy with my Catto. Best $1,650 I've spent. I run a 160HP, 0-320-B2A and am using Craig's three bladed 66 inch diameter and 72 inch pitch. Craig said this should give you about 195 to 200mph at full throttle and at low altitude should give you about 2800rpm and at 7-8K ft about 2700rpm. Still working on verifying these numbers. Sure is smooth.
Pat Long
3CM
Bay City, MI
I'm extremely happy with my Catto. Best $1,650 I've spent. I run a 160HP, 0-320-B2A and am using Craig's three bladed 66 inch diameter and 72 inch pitch. Craig said this should give you about 195 to 200mph at full throttle and at low altitude should give you about 2800rpm and at 7-8K ft about 2700rpm. Still working on verifying these numbers. Sure is smooth.
Pat Long
3CM
Bay City, MI
I've got 40 hrs on my rv6 which has a aerosport 0-320D1A driving a MT 2 blade i purchased through van's. I know of no one else who has this setup. I went with the MT over the hartzel purely for weight reasons (at least 20 lbs) since i was trying to build as efficient machine as possible. I'm a low time pilot (180 hrs in skyhawks and champs over 15 years prior to flying my RV6) and I was originally going to install a fixed pitch on the aircraft but was talked into the CS by our chapter tech advisor who said the CS would make the airplane much easier to slow down.
My first flight in a RV aircraft was a couple of years ago when i was in the northwest during the summer and did some flying with Mike Seager in his RV7. That aircraft has a 320 and fixed pitch prop. After flying with him I thought that I had made a mistake going with the CS since his RV7 performed much better than anything i had ever flown and his technique in the vicinity of the airport minimized any problems caused by excess speed.
However, prior to flying my RV6 the insurance company required 5 hrs of dual and a CFI signoff so i went out and found Alex D in the Dallas area who has a RV6 with a 360 and CS prop (I had still never flown behind a CS prop). The performance of his airplane with that setup was breathtaking to me. The thing accelerated like a rocket and the CS covered up a lot of high/fast approaches since the increased drag caused by the propeller in fine pitch would really bring the airplane down quickly. I was starting to think that the CS wasn't a mistake after all.
After only 40hrs I'm very happy with the CS on my airplane. The biggest adjustment for me is managing the drag variable in the process of landing the airplane since when you reduce power the propeller drag changes (increases). I must admit I'm still getting used to this aspect of the CS propeller. But I have absolutely no problem getting the thing slowed down to pattern speed and the takeoff performance is much better than another locally based 160hp RV6 who has a fixed pitch prop. Is it worth the extra (at least) $6k or so? It depends on what your looking for and how much you're got to spend. You can always go with the fixed pitch in the beginning and upgrade later if you've got the right crankshaft. This will still be a much better performing aircraft than any light cessna or champ. The CS will never pay back it's extra upfront and maintenance costs through increased efficiency but it sure is nice climbing out at gross weight at 1500'/min on 160hp!
Doug Meloche
My first flight in a RV aircraft was a couple of years ago when i was in the northwest during the summer and did some flying with Mike Seager in his RV7. That aircraft has a 320 and fixed pitch prop. After flying with him I thought that I had made a mistake going with the CS since his RV7 performed much better than anything i had ever flown and his technique in the vicinity of the airport minimized any problems caused by excess speed.
However, prior to flying my RV6 the insurance company required 5 hrs of dual and a CFI signoff so i went out and found Alex D in the Dallas area who has a RV6 with a 360 and CS prop (I had still never flown behind a CS prop). The performance of his airplane with that setup was breathtaking to me. The thing accelerated like a rocket and the CS covered up a lot of high/fast approaches since the increased drag caused by the propeller in fine pitch would really bring the airplane down quickly. I was starting to think that the CS wasn't a mistake after all.
After only 40hrs I'm very happy with the CS on my airplane. The biggest adjustment for me is managing the drag variable in the process of landing the airplane since when you reduce power the propeller drag changes (increases). I must admit I'm still getting used to this aspect of the CS propeller. But I have absolutely no problem getting the thing slowed down to pattern speed and the takeoff performance is much better than another locally based 160hp RV6 who has a fixed pitch prop. Is it worth the extra (at least) $6k or so? It depends on what your looking for and how much you're got to spend. You can always go with the fixed pitch in the beginning and upgrade later if you've got the right crankshaft. This will still be a much better performing aircraft than any light cessna or champ. The CS will never pay back it's extra upfront and maintenance costs through increased efficiency but it sure is nice climbing out at gross weight at 1500'/min on 160hp!
Doug Meloche
hevansrv7a
Well Known Member
I did the math. Going to the O-360 for about 2K will probably get the same increase in climb performance for less money, less complexity, fewer maintenance issues, etc. Isn't it great that we can, as builders of experimental aircraft, make our own choices?dmeloche said:
Leonard_Smith_nz
Active Member
Propeller efficiency
All,
I find this thread really interesting. A while back I posted an equation that stated:
Speed in knots = RPM (hundreds) * Pitch (inches) / 12.15
using Dave Dollarhide's numbers
e.g. Speed = 27 * 83 / 12.15
= 184.4 kts
Now, my 'magic' formula is a very idealized scenario and I'm sure will make the likes of GMC toss and turn in his bed with anguish It's based on the common sense assumption that in an ideal world the propeller will propel the aircraft forward by a distance equivalent to the pitch for every rotation of the prop.
Dave says he gets just short of 190 mph (165 kts). That translates to roughly 88% efficiency. Checking his numbers for 2450 rpm shows a consistent result.
What I did not know before today was what the efficiency of the FP Sensenich would be (my proposed setup as well). 88% sounds great and I'm looking forward to 165kts at 2700 rpm.
My question: A previous post (by GMC I think) showed the CS at roughly 82% efficiency. Why the big difference?
Regards,
Leonard
RV6 in New Zealand (O-360 with 85" FP Sensenich)
Ps. A tip for doing basic conversions. Go to Google and type "190 mph to knots" in the search bar (without the quotes...just shown here for clarity)
All,
I find this thread really interesting. A while back I posted an equation that stated:
Speed in knots = RPM (hundreds) * Pitch (inches) / 12.15
using Dave Dollarhide's numbers
e.g. Speed = 27 * 83 / 12.15
= 184.4 kts
Now, my 'magic' formula is a very idealized scenario and I'm sure will make the likes of GMC toss and turn in his bed with anguish
It's based on the common sense assumption that in an ideal world the propeller will propel the aircraft forward by a distance equivalent to the pitch for every rotation of the prop. Dave says he gets just short of 190 mph (165 kts). That translates to roughly 88% efficiency. Checking his numbers for 2450 rpm shows a consistent result.
What I did not know before today was what the efficiency of the FP Sensenich would be (my proposed setup as well). 88% sounds great and I'm looking forward to 165kts at 2700 rpm.
My question: A previous post (by GMC I think) showed the CS at roughly 82% efficiency. Why the big difference?
Regards,
Leonard
RV6 in New Zealand (O-360 with 85" FP Sensenich)
Ps. A tip for doing basic conversions. Go to Google and type "190 mph to knots" in the search bar (without the quotes...just shown here for clarity)
hevansrv7a said:I did the math. Going to the O-360 for about 2K will probably get the same increase in climb performance for less money, less complexity, fewer maintenance issues, etc. Isn't it great that we can, as builders of experimental aircraft, make our own choices?
I agree, if you're only concerned with climb rate/$ go with the 0-360 and fixed pitch prop.
