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Whirlwind vs Aerotek propellers?
- Thread starter Chele
- Start date
randylervold
moderator
Never heard of Aerotek but found this web site...
http://homepages.ihug.co.nz/~aerotek/index.htm
I can't tell from the web site, is this even a constant speed prop? If not then you have apples & oranges here. Also, it looks as if the Aerotek was developed for smaller engines with the O-320 being the largest.
http://homepages.ihug.co.nz/~aerotek/index.htm
I can't tell from the web site, is this even a constant speed prop? If not then you have apples & oranges here. Also, it looks as if the Aerotek was developed for smaller engines with the O-320 being the largest.
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gmcjetpilot
Well Known Member
Interesting - Observation
I assuem you have hyd hollow crank or are you thinking elec c/s? I'm not a fan of the latter but its a necessary evil for some. The MT would be my choice if I had to go with elec c/s prop. If you have a solid crank than why not go fixed prop? Why three blades? If I was going fixed, I like the Sensenich. Hyd c/s the hartzell.
This may be an option for you if you have solid crank: Check this thread out and post #10.
http://www.vansairforce.com/community/showthread.php?t=25292&highlight=avia
Avia makes a prop that varies prop angle by aerodynamics. With control fins or vains on the spinner, plus RPM, the prop automatically adjusts the blade angle. It's very clever. It is not really consant speed or fixed. I know little about it. It is interesting and there is some feed back above. I remember seeing them in the Oshkosh vendor's area a long time ago, over 10 years. I thought it was a cool idea. Russ Daves of Lubbock, TX, says he would do it again, it was a step up from the fixed pitch he had. We are talking two blades of course.
Some observations and comments from the Aerotek web site Randy posted above:
Price is not that cheap?
Where are they from? (New Zeland)
references/feedback from customers?
There is a lot of blade root sticking out past the spinner.
They compare them self to Airmaster a lot:
http://www.propellor.com/wa.asp?idWebPage=3672
(I gather this is variable pitch or elect c/s?)
Couple of negatives or observations. You are US based? Dealing with New Zealand has some drawbacks, right. Also props that are often scaled up for small engines like Rotax tend to have issues on Lycs. Ivo props where OK on ultra lights and small engines, less than 100 hp, but when scaled up to the Lyc, issues arose. The LYC has a hard hitting power pulse that many small engines don't. The prop needs to be very robust.
What about fixed pitch prop? If you don't have hyd c/s prop ability, would you consider fixed pitch? The fixed will give near the same overall performance and cost way less. Just a thought. There is nothing wrong with fixed pitch. They tend to be lighter, cheaper and almost no maintence or issues. Many of the fixed prop makers Bernie Warnke and Catto to name two make three blade props. If you have a RV, Sensenich is very good. If you have another type plane there are many fixed wood or wood/glass prop makers like Catto, Warnke, Prince, Aymar-DeMuth, Sterba, Felix, Pacesetter, Props Inc., Warp Drive.
I am not selling anything, but look at McCauley and Hartzell historically. McCauley in business since 1938 and Hartzell built its first prop in 1917. Over the 70 or 90 years, some of their prop models ended up developing problems after being in service for many years, so AD's, mods and redesigns where needed. They learned and evolved; their new props are very well understood, benefiting from lots of refinement and certification on Lycs. Hartzell of couse is courting the RV community, making props just for our plane and even other kit planes like Lancair and Rockets (HRII, F1).
A new prop company is making you R&D, the test pilot. Even real nice props like the Whirlwind had some issues customers found after being in service. No offense to the small prop companies, but a Lyc is a real aircraft engine and should probably have something robust and substantial prop attached to it. A fixed prop is a low risk option and will cost you many thousands less. Also dealing with a prop company half way around the world is also a challenge. Just a caution is all. Shipping cost might be a drag.
My opinion if you can't go with a real hydraulic constant speed prop (Hartzell, Whirlwind, MT..... etc) than get a fixed prop. The "in-between" electric props and ground adjustable props seem complicated for little gain, in my opinion. Sometimes its needed for special applications, but for most, a fixed prop is going to be good enough if Hyd constant speed props are possible or practical.
PS: Why 3 blades? Really there is little gain and I don't buy a three blade is way smoother or a two blade can not be balanced. Sure there might be some small difference but not as great as some might lead you to believe.
What airplane do you have? Can your O320 take a hyd constant speed prop? What prop do you have now?
I assuem you have hyd hollow crank or are you thinking elec c/s? I'm not a fan of the latter but its a necessary evil for some. The MT would be my choice if I had to go with elec c/s prop. If you have a solid crank than why not go fixed prop? Why three blades? If I was going fixed, I like the Sensenich. Hyd c/s the hartzell.
This may be an option for you if you have solid crank: Check this thread out and post #10.
http://www.vansairforce.com/community/showthread.php?t=25292&highlight=avia
Avia makes a prop that varies prop angle by aerodynamics. With control fins or vains on the spinner, plus RPM, the prop automatically adjusts the blade angle. It's very clever. It is not really consant speed or fixed. I know little about it. It is interesting and there is some feed back above. I remember seeing them in the Oshkosh vendor's area a long time ago, over 10 years. I thought it was a cool idea. Russ Daves of Lubbock, TX, says he would do it again, it was a step up from the fixed pitch he had. We are talking two blades of course.
Some observations and comments from the Aerotek web site Randy posted above:
Price is not that cheap?
Where are they from? (New Zeland)
references/feedback from customers?
There is a lot of blade root sticking out past the spinner.
They compare them self to Airmaster a lot:
http://www.propellor.com/wa.asp?idWebPage=3672
(I gather this is variable pitch or elect c/s?)
Couple of negatives or observations. You are US based? Dealing with New Zealand has some drawbacks, right. Also props that are often scaled up for small engines like Rotax tend to have issues on Lycs. Ivo props where OK on ultra lights and small engines, less than 100 hp, but when scaled up to the Lyc, issues arose. The LYC has a hard hitting power pulse that many small engines don't. The prop needs to be very robust.
What about fixed pitch prop? If you don't have hyd c/s prop ability, would you consider fixed pitch? The fixed will give near the same overall performance and cost way less. Just a thought. There is nothing wrong with fixed pitch. They tend to be lighter, cheaper and almost no maintence or issues. Many of the fixed prop makers Bernie Warnke and Catto to name two make three blade props. If you have a RV, Sensenich is very good. If you have another type plane there are many fixed wood or wood/glass prop makers like Catto, Warnke, Prince, Aymar-DeMuth, Sterba, Felix, Pacesetter, Props Inc., Warp Drive.
I am not selling anything, but look at McCauley and Hartzell historically. McCauley in business since 1938 and Hartzell built its first prop in 1917. Over the 70 or 90 years, some of their prop models ended up developing problems after being in service for many years, so AD's, mods and redesigns where needed. They learned and evolved; their new props are very well understood, benefiting from lots of refinement and certification on Lycs. Hartzell of couse is courting the RV community, making props just for our plane and even other kit planes like Lancair and Rockets (HRII, F1).
A new prop company is making you R&D, the test pilot. Even real nice props like the Whirlwind had some issues customers found after being in service. No offense to the small prop companies, but a Lyc is a real aircraft engine and should probably have something robust and substantial prop attached to it. A fixed prop is a low risk option and will cost you many thousands less. Also dealing with a prop company half way around the world is also a challenge. Just a caution is all. Shipping cost might be a drag.
My opinion if you can't go with a real hydraulic constant speed prop (Hartzell, Whirlwind, MT..... etc) than get a fixed prop. The "in-between" electric props and ground adjustable props seem complicated for little gain, in my opinion. Sometimes its needed for special applications, but for most, a fixed prop is going to be good enough if Hyd constant speed props are possible or practical.
PS: Why 3 blades? Really there is little gain and I don't buy a three blade is way smoother or a two blade can not be balanced. Sure there might be some small difference but not as great as some might lead you to believe.
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Sorry, here's my specs
Sorry, I have a Glasair I TD, extended hub CS hartwell AL prop. There is not much ground clearance which resulted in a prop strike on a bumpy strip. Damage could not be repaired. I was looking at 3 blade to get more ground clearance so it doesn't happen again. Was initially looking at MT but they are very expensive, the wait time is over 3 months, shipping is expensive, and their 3 blade prop is virtually the same length as their 2 blade prop for this configuration. I was going to go with Whirlwind: much cheaper, local, wait time only about 1 month, diameter much shorter. However, then a friend started sending me links from your forum about Whirlwinds that had come apart and that had had other issues, so my confidence level went way down. I ran across some smaller companies like Quinti and Aerotek 2000. Couldn't find any info on Quinti. Aerotek responded and said they had 3 and 4 blade electric CS props with feathering they designed for a Lancair 320, but I couldn't find any other reviews on the web. Their price was a good beit cheaper than Whirlwind and he said shipping cost was $200 (they absorb a lot of the cost). Do you think Whirlwind has fixed all the issues with their props?
Sorry, I have a Glasair I TD, extended hub CS hartwell AL prop. There is not much ground clearance which resulted in a prop strike on a bumpy strip. Damage could not be repaired. I was looking at 3 blade to get more ground clearance so it doesn't happen again. Was initially looking at MT but they are very expensive, the wait time is over 3 months, shipping is expensive, and their 3 blade prop is virtually the same length as their 2 blade prop for this configuration. I was going to go with Whirlwind: much cheaper, local, wait time only about 1 month, diameter much shorter. However, then a friend started sending me links from your forum about Whirlwinds that had come apart and that had had other issues, so my confidence level went way down. I ran across some smaller companies like Quinti and Aerotek 2000. Couldn't find any info on Quinti. Aerotek responded and said they had 3 and 4 blade electric CS props with feathering they designed for a Lancair 320, but I couldn't find any other reviews on the web. Their price was a good beit cheaper than Whirlwind and he said shipping cost was $200 (they absorb a lot of the cost). Do you think Whirlwind has fixed all the issues with their props?
randylervold
moderator
Give your situation and needs I think the WW 151-H might just be the perfect solution. I believe there would be no issues with a prop you would buy now with the -H blades (redesigned steel ferrules). The good news is that they have forthright and supportive in the several issues that have come up along the way. As you indicate there was one instance of a pitch pin working it's way out of the old aluminum ferrule, I'm told that's virtually impossible with the steer ferrule they are now shipping. There's a thread in this forum from the owner of the Lancair this happened on, a nicely written factual account actually.
I have one on my RV-3B and it is performing beautifully. I needed a lightweight solution so a Hartzell just wasn't an option, I'm happy with the 151-H in every regard.
gmcjetpilot
Well Known Member
What randy said
Oh ok, yea go hyd and three blade for more clearance. WW or MT. I know Hartzell makes a two blade prop for the Lancair 360 that is like 68" dia. Give them a call. Sorry to hear about your prop. Obviously a three blade metal Hartzell is too heavy for your bird.
STAY AWAY FROM ELECTRIC C/S since you have Hyd. Hyd is much faster reacting and once its set up is almost maintenance free. Elec props where used in the 40's and 50's on some planes but they went away fairly quickly because Hyd is superior. One of the planes used in WWII transport had electric props and was known as the widow maker because the elec c/s prop would go wacky and kill pilots on takeoff. Also on a single engine plane you don't need or want feathering. You are just asking for trouble.
Yes MT has had problems as all props can. I don't know what you heard but you have to get all the details. Sometimes stories grow as they are told. A Hartzell came apart. Well the guy hit some stumps landing in Alaska and curled the blades. He personally bent them or tweaked them as straight as he could it with a crow bar, than hacksawed down the ends himself. He flew quite a bit before one of the blades left the plane.
Hartzell, in my opinion is the best bargain, best performing and best supported overall. However when you get into a specialty props like the wood/glass MT or composite WW, they are worth a look. Hartzell does not make an equiv model. Their three blade composites are for larger planes or serious Aerobatics.
You have a goal of increasing ground clearance. Your Hartzell was 72" dia? So going to a 78" prop will save 2". Will that make a big difference , lets say in the incident that bent the Hartzell?
The MT does cost more to buy and repair and the negative in my opinion is logistics, dealing with a prop made and repaired in Germany, namely shipping.
I have heard great things about the Whirlwind three blade prop.
I will warn you, touch composite prop blades to the ground, whilst spinning you are going to be hurting the pocket book for sure. Repair? May be possible but will cost you a bundle. It all depends on how hard you hit. A slight "tag" at the tip will be easier to repair, but most likely means removal from the plane and shipping to a repair center. Where a metal Hartzell gouge or nick might be filed right on the plane. If the Hartzell is bent slightly it can be repaired (sometimes as you know). However a significant strike requires prop removal. Any prop hit hard enough will become trash.
You will also lose a little speed with three blades and thicker composite blades. Hartzell two blades tend to be faster because metal blades are thinner. On the plus side the composite props are lighter. Check you W&B. Is losing 10-20 lbs off the prop OK. Also on the plus you might find the three blade to be quieter and even feel smoother.
Oh ok, yea go hyd and three blade for more clearance. WW or MT. I know Hartzell makes a two blade prop for the Lancair 360 that is like 68" dia. Give them a call. Sorry to hear about your prop. Obviously a three blade metal Hartzell is too heavy for your bird.
STAY AWAY FROM ELECTRIC C/S since you have Hyd. Hyd is much faster reacting and once its set up is almost maintenance free. Elec props where used in the 40's and 50's on some planes but they went away fairly quickly because Hyd is superior. One of the planes used in WWII transport had electric props and was known as the widow maker because the elec c/s prop would go wacky and kill pilots on takeoff. Also on a single engine plane you don't need or want feathering. You are just asking for trouble.
Yes MT has had problems as all props can. I don't know what you heard but you have to get all the details. Sometimes stories grow as they are told. A Hartzell came apart. Well the guy hit some stumps landing in Alaska and curled the blades. He personally bent them or tweaked them as straight as he could it with a crow bar, than hacksawed down the ends himself. He flew quite a bit before one of the blades left the plane.
Hartzell, in my opinion is the best bargain, best performing and best supported overall. However when you get into a specialty props like the wood/glass MT or composite WW, they are worth a look. Hartzell does not make an equiv model. Their three blade composites are for larger planes or serious Aerobatics.
You have a goal of increasing ground clearance. Your Hartzell was 72" dia? So going to a 78" prop will save 2". Will that make a big difference , lets say in the incident that bent the Hartzell?
The MT does cost more to buy and repair and the negative in my opinion is logistics, dealing with a prop made and repaired in Germany, namely shipping.
I have heard great things about the Whirlwind three blade prop.
I will warn you, touch composite prop blades to the ground, whilst spinning you are going to be hurting the pocket book for sure. Repair? May be possible but will cost you a bundle. It all depends on how hard you hit. A slight "tag" at the tip will be easier to repair, but most likely means removal from the plane and shipping to a repair center. Where a metal Hartzell gouge or nick might be filed right on the plane. If the Hartzell is bent slightly it can be repaired (sometimes as you know). However a significant strike requires prop removal. Any prop hit hard enough will become trash.
You will also lose a little speed with three blades and thicker composite blades. Hartzell two blades tend to be faster because metal blades are thinner. On the plus side the composite props are lighter. Check you W&B. Is losing 10-20 lbs off the prop OK. Also on the plus you might find the three blade to be quieter and even feel smoother.
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Jconard
Well Known Member
My WW151 is not flying yet, but I wanted to comment briefly on my experience with the company.
First the presales disclosure was excellent. The company engineers were willing to discuss everything they had done and considered when designing the original 150 and with the change to the newer Opti-Q Airfoil. They evey had an extended hub prop with a custom spinner to ease my Sam james installation.
While building, some issues have come up with the prop. It would not appear that the issues would effect my O-320 installation, nonetheless, the company agreed to put new blades in my prop at no charge to me. Again I had the opportunity to spend considerable time discussing the production changes, and testing methodologies with Bill Koleno and others on the engineering staff. In the end, since I had an O-320, they agreed to have me fly a few hundred hours first, and still honor the agreement, so that I could get my project of the ground without delay, and so that they would have another data point from a real field installation.
As the first flight draws near, there was a recent pin failure on a lancair. Again, Bill Koleno was available to talk to me and discuss with utter honesty what happened. They have changed several of the processes they use to do some of the upgrades. The fact that one blade went negative, and stayed attached is, in my opinion, a great testiment to the blade and retention design.
It was so refreshing to get an engineer on the phone who said "yeah we made a mistake" and here are the three concrete steps we are taking to fix the problem and eliminate any future occurence.
Because the waranty on the props starts at shipment, they could very well have said...buy the blades if you want them. But this company has really stepped up. To have them instead say "finish your project, fly some hours for us, and we'll get you the blades" gives me great confidence in the quality of the product and the committment of the company to experimental aviation. They have even been willing to put another prop together and swap them if need be to minimise downtime.
I know they have worked with everyone else affected by the initial prop issues. I know it has been at great expense to them. But they made the choice to do the right thing, even if they could likely have gotten away (legally) with doing the wrong thing. This committment puts them in Bart Lalonde or Steinair territory when it comes to customer support.
If I get to build another RV, it will have a WW on it (might be a 200 model prop...depending on engine). The quality and support are simply perfect in my opinion.
In the age of less than upright dealing (D2A Chelton), and less than honest manufacturers (pre sales disclosure and honesty), Whirlwind is, in my mind, a real stand out company.
First the presales disclosure was excellent. The company engineers were willing to discuss everything they had done and considered when designing the original 150 and with the change to the newer Opti-Q Airfoil. They evey had an extended hub prop with a custom spinner to ease my Sam james installation.
While building, some issues have come up with the prop. It would not appear that the issues would effect my O-320 installation, nonetheless, the company agreed to put new blades in my prop at no charge to me. Again I had the opportunity to spend considerable time discussing the production changes, and testing methodologies with Bill Koleno and others on the engineering staff. In the end, since I had an O-320, they agreed to have me fly a few hundred hours first, and still honor the agreement, so that I could get my project of the ground without delay, and so that they would have another data point from a real field installation.
As the first flight draws near, there was a recent pin failure on a lancair. Again, Bill Koleno was available to talk to me and discuss with utter honesty what happened. They have changed several of the processes they use to do some of the upgrades. The fact that one blade went negative, and stayed attached is, in my opinion, a great testiment to the blade and retention design.
It was so refreshing to get an engineer on the phone who said "yeah we made a mistake" and here are the three concrete steps we are taking to fix the problem and eliminate any future occurence.
Because the waranty on the props starts at shipment, they could very well have said...buy the blades if you want them. But this company has really stepped up. To have them instead say "finish your project, fly some hours for us, and we'll get you the blades" gives me great confidence in the quality of the product and the committment of the company to experimental aviation. They have even been willing to put another prop together and swap them if need be to minimise downtime.
I know they have worked with everyone else affected by the initial prop issues. I know it has been at great expense to them. But they made the choice to do the right thing, even if they could likely have gotten away (legally) with doing the wrong thing. This committment puts them in Bart Lalonde or Steinair territory when it comes to customer support.
If I get to build another RV, it will have a WW on it (might be a 200 model prop...depending on engine). The quality and support are simply perfect in my opinion.
In the age of less than upright dealing (D2A Chelton), and less than honest manufacturers (pre sales disclosure and honesty), Whirlwind is, in my mind, a real stand out company.
Another WW kudo
When I decided to change to a constant speed prop I had a different type of problem to solve. Since my airplane was already completed I had to have the correct spacing on the cowling.
I contacted WW and sent them my measurements and they actually fabricated a slightly different backing plate that moved the spinner forward to accommodate my needs.
I e-mailed and talked and visited face to face at OSH and always got the "we'll work with you and make it work" attitude.
I highly recommend both Whirlwind and American Propellers as great companies to do business with.
When I decided to change to a constant speed prop I had a different type of problem to solve. Since my airplane was already completed I had to have the correct spacing on the cowling.
I contacted WW and sent them my measurements and they actually fabricated a slightly different backing plate that moved the spinner forward to accommodate my needs.
I e-mailed and talked and visited face to face at OSH and always got the "we'll work with you and make it work" attitude.
I highly recommend both Whirlwind and American Propellers as great companies to do business with.
I don't know if these are the same people as "AeroTech" listed below, but the Aero Composites site here looks like it is another alternative to MT or Whirlwind. Their site is VERY detailed, and if it is indicative of the work they do then I would guess they run a pretty good shop.
I haven't seen many posts about them, so don't know if they are as good as they claim. Which would be good, because they are claiming BETTER top speed compared to an aluminum prop.
Anyone have any experience with them?
I haven't seen many posts about them, so don't know if they are as good as they claim. Which would be good, because they are claiming BETTER top speed compared to an aluminum prop.
Anyone have any experience with them?
Thanks for the info. Yes, the Areotek 2000 uses an electric governor so I will stay away from that. Regarding, "will 2" make a big difference" - It can't hurt! I hadn't thought about the very light strike on a composite vs metal issue. Good point. However, I still think I will go with the WW for the albeit small extra clearance and for nose weight. When I fly by myself I have to put ballast in rear, so less weight up front will be nice. Thanks.
No, Aero Composite and AeroTek are not the same Company. I didn't consider the Aero Composite because of price. They might be great props, but they are very, very proud of their propellers.
Also found out that most of the AeroTek props are manufactured and marketed under the Airmaster brand.
I think I remember Airmaster - there may be a reason they changed their name...
And yes, the Aero Composite folks value their work highly. I don't think I'd pay a 50% premium for a 2% performance gain, but that's just me.
gmcjetpilot
Well Known Member
Aero Composite
Lazy8's experience with the Aero Composite was mixed; it spit a abrasion strip off. On the good side they customer service was good, however he eventually traded it out for a Hartzell. The Aero Comp is also a stiff graphite prop so it feels more like a metal prop than wood.
The MT was fine but he noticed a big loss in speed from the Hartzell, which is expected and well documented. Thicker blades on the MT prop are due to them being made of wood and glass. Metal blades are thinner, and therefore have better performance. To summarize he went full circle and ended up back at hartzell.
Three blade in the HP and Speed range we run at is a slight disadvantage from TWO blade props. Now on the plus MT is naturally smooth because of the natural material, wood, has inherent damping properties. Three blades do offer a different air pulse over the airframe and may give more ground clearance if you go with a smaller diameter.
The Aero Composite is high tech aerospace solid composite (graphite). That makes it strong, light and expensive. The down side is they are as stiff (stiffer) than aluminum blades. They are almost like metal props. So they lose the smoothness award.
Metal props can be (and should be) very smooth. Wood props are always going to have less buzz, particularly at certain RPM's, but in normal operation in cruise the difference should be small.
A metal prop needs to be balanced to the engine. The engine can't have its own vibration issues like uneven firing of the cylinders or gross imbalance in the rotating assemblies. Also using a high quality LORD engine mount/vibration dampers (verses cheap ones) makes a difference. A wood prop can cover up many sins.
I don't want my advocacy for Hartzell to be interpreted as bashing of other brands, but the "BA" prop makes tailored for the RV; it's the bomb diggity. It's less money, has the best performance and best support behind it, bar none, in my opinion. It is a "no brainer" in my opinion.
The wood MT, composite WW or Aero Composite are specialty props. The are from small "boutique" companies, which don't have service as widely available as Hartzell. However the customer service from all these companies I have heard is excellent. They just cost more to buy and repair is a fair statement.
If you MUST have three blades, composite props lightness pays off. A Hartzell three blade metal prop is a little too heavy for most RV's. They are OK for Rockets.
Here are some numbers from the RVator prop fly off done a few years ago:
In order of speed (mph) for normal cruise, 8,000' WOT 2,500 rpm: (all 2 blade except where noted)
(208.9) Hartzell BA 72"
(206.9) WW 200RV 72"*
(205.6) WW 200C 77"
(205.4) Hartzell 7661 72"
(204.6) Aero Composite 72"
(201.9) WW 150 3-blade 69"
200.7 MT MRV12B 3-blade 72"
*77" is a typo I believe in RVator Ref.
You can see the older Hartzell and Aero Composite are about the same. The "BA" prop is a clear performer.
The two three blade props are at the bottom of the heap and not even close. That should stop this debate that three blades is not slower. Look if you have a turbo prop or P-51 you need more blades because of the shaft HP and higher speeds, but on a RV its not a performance move, its for aesthetics or precived smoothness.
Yea on their web site there is a RV-8'er with a IO-390 that does well in the Gentelman's/Airshow cross country races. The one thing is they are the most expensive. Another RV-8'er tried Aero Composite, MT and Hartzell. He has a write up on his web site. http://www.lazy8.net/proptest.htm To summarize his experience:
Lazy8's experience with the Aero Composite was mixed; it spit a abrasion strip off. On the good side they customer service was good, however he eventually traded it out for a Hartzell. The Aero Comp is also a stiff graphite prop so it feels more like a metal prop than wood.
The MT was fine but he noticed a big loss in speed from the Hartzell, which is expected and well documented. Thicker blades on the MT prop are due to them being made of wood and glass. Metal blades are thinner, and therefore have better performance. To summarize he went full circle and ended up back at hartzell.
Three blade in the HP and Speed range we run at is a slight disadvantage from TWO blade props. Now on the plus MT is naturally smooth because of the natural material, wood, has inherent damping properties. Three blades do offer a different air pulse over the airframe and may give more ground clearance if you go with a smaller diameter.
The Aero Composite is high tech aerospace solid composite (graphite). That makes it strong, light and expensive. The down side is they are as stiff (stiffer) than aluminum blades. They are almost like metal props. So they lose the smoothness award.
Metal props can be (and should be) very smooth. Wood props are always going to have less buzz, particularly at certain RPM's, but in normal operation in cruise the difference should be small.
A metal prop needs to be balanced to the engine. The engine can't have its own vibration issues like uneven firing of the cylinders or gross imbalance in the rotating assemblies. Also using a high quality LORD engine mount/vibration dampers (verses cheap ones) makes a difference. A wood prop can cover up many sins.
I don't want my advocacy for Hartzell to be interpreted as bashing of other brands, but the "BA" prop makes tailored for the RV; it's the bomb diggity. It's less money, has the best performance and best support behind it, bar none, in my opinion. It is a "no brainer" in my opinion.
The wood MT, composite WW or Aero Composite are specialty props. The are from small "boutique" companies, which don't have service as widely available as Hartzell. However the customer service from all these companies I have heard is excellent. They just cost more to buy and repair is a fair statement.
If you MUST have three blades, composite props lightness pays off. A Hartzell three blade metal prop is a little too heavy for most RV's. They are OK for Rockets.
Here are some numbers from the RVator prop fly off done a few years ago:
In order of speed (mph) for normal cruise, 8,000' WOT 2,500 rpm: (all 2 blade except where noted)
(208.9) Hartzell BA 72"
(206.9) WW 200RV 72"*
(205.6) WW 200C 77"
(205.4) Hartzell 7661 72"
(204.6) Aero Composite 72"
(201.9) WW 150 3-blade 69"
200.7 MT MRV12B 3-blade 72"
*77" is a typo I believe in RVator Ref.
You can see the older Hartzell and Aero Composite are about the same. The "BA" prop is a clear performer.
The two three blade props are at the bottom of the heap and not even close. That should stop this debate that three blades is not slower. Look if you have a turbo prop or P-51 you need more blades because of the shaft HP and higher speeds, but on a RV its not a performance move, its for aesthetics or precived smoothness.
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"In order of speed (mph) for normal cruise, 8,000' WOT 2,500 rpm: (all 2 blade except where noted)
(208.9) Hartzell BA 72"
(206.9) WW 200RV 72"*
(205.6) WW 200C 77"
(205.4) Hartzell 7661 72"
(204.6) Aero Composite 72"
(201.9) WW 150 3-blade 69"
200.7 MT MRV12B 3-blade 72" "
Is it inconceivable that the 3 blade props would be optimized at a different RPM than the 2 blade props? Perhaps rather than using a standardized MAP/RPM it would be more informative to just find the highest speed for each prop?
Dave
(208.9) Hartzell BA 72"
(206.9) WW 200RV 72"*
(205.6) WW 200C 77"
(205.4) Hartzell 7661 72"
(204.6) Aero Composite 72"
(201.9) WW 150 3-blade 69"
200.7 MT MRV12B 3-blade 72" "
Is it inconceivable that the 3 blade props would be optimized at a different RPM than the 2 blade props? Perhaps rather than using a standardized MAP/RPM it would be more informative to just find the highest speed for each prop?
Dave
Great writeup! I would add a couple of observations.
1. We don't know if this was truly a one-time event. If it was, and if they have corrected their manufacturing technique, then the quality issue doesn't sound like a factor.
Remember, even without the sheath his engine was still running and he could still land normally - it was only his (understandable) caution over the vibration which limited his use of power. I lost half a blade once (wooden propeller) which was likely much worse in vibration than his situation; yet I was cognizant that adding power was an option if I absolutely needed to do so. At the time when I initially lost the prop, I was at 8,500' and 15 miles from land in the Bahamas - and I would happily have beaten my motor mount to death to avoid landing in the water. As it turned out, I didn't need to. The point is, though that his prop did NOT suffer a catastrophic failure - and I DO have a friend who lost TWO Hartzell blades - so a certified prop is no guarantee.
2. The Aero Composites performed virtually as well as the Hartzell, but weighs 21 pounds less. That is rather significant when perched at the very front tip of your airplane.
3. The stainless steel leading edge on the Aero Composites is actually less likely to suffer rain / hail damage than is the soft aluminum leading edge of a Hartzell. If you fly into weather with regularity, this could be a factor.
4. A scenario you did not address in your writeup is the one where someone wants to use a shorter propeller (switch from 2 to 3 blades) and cannot afford the extra weight. That 21 pounds could also spell the difference for some builders between an IO-360 and an IO-390 up front, so in that case weight translates to power.
So, just to be fair to the Aero Composites guys there may be some very good reasons for choosing their product even given the premium - and with experience they may get the price down, too.
Jconard
Well Known Member
http://www.romeolima.com/RV8/Prop.htm
This comparison shows closer speeds
WW 150 top speed 215
Hartzell top speed 215
WW 150 Cruise 203
Hartzell cruise 207
The WW RV200 was the fastest of all, and the 150 climbed best.
I have been told by WW and a number of users that the 151's tapered tip (they call it opti Q) makes the 151 markedly faster. I would think it is still a little slower than a two blade, but will definitely report when I get flying.
This comparison shows closer speeds
WW 150 top speed 215
Hartzell top speed 215
WW 150 Cruise 203
Hartzell cruise 207
The WW RV200 was the fastest of all, and the 150 climbed best.
I have been told by WW and a number of users that the 151's tapered tip (they call it opti Q) makes the 151 markedly faster. I would think it is still a little slower than a two blade, but will definitely report when I get flying.
