Which Prop

I have a RV7A IO360 Forward facing Sump, 180hp, AeroSport Engine. I'm ready to purchase a prop. I'm trying to decide between the 72" C2YK-1BF/F7666A4 that Dan has on his plane OR the C2YR-1BF/F7496-2 blended air foil. There is about $150 difference in Vans prices. Does anyone have any experience with both? Dan seems to have a fast plane with his.
Thanks.....Rob

Whirlwind

It's not one of your options ... but my choice is one of these plastic dealies.

http://www.whirlwindaviation.com/series200rv.php

Didn't Van's run tests and determine the BA to be a few mph faster? I'd personally go with the blended airfoil for a parallel valve 360.

Somewhat unrelated rant...

Hartzell recently came out with a new BA blade, the 7497, which is approved for use with the angle valve IO-360 (at least some models...read on). Lately I've been saying that if I had to get a new prop today, I would go with the BA if it was available.

However! I looked carefully at the TCDS and found that the 7497 is actually not approved (yet?) for my IO-360-A1B6 engine. It's approved for the IO-360-A1A, among other non-counterweighted angle valve models, but not the -A1B6.

And what's interesting is that the 7497 does have the following placarded RPM restriction:

Continuous operation is prohibited above 24 inches manifold pressure between 2350 and 2550 RPM

Click to expand...

...whereas the F7666 blade which I have currently has an unlimited RPM range, no restrictions whatsoever, with my particular engine. I do cruise between 2100 and 2300 fairly frequently these days.

So I take back what I've been saying. Until/unless the 7497 (or another BA blade) is approved for the IO-360-A1B6 with no RPM restrictions, I would not be interested in upgrading.

However, for a 180hp parallel valve 360, where you're gonna have a placarded RPM "avoid continuous operation" range regardless of BA 7496 vs. non-BA 7666, I'd go with the BA.

Wasn't it Randy Lervold that did some of this testing Dan? I know I read an excellent write-up, but it isn't on his site - maybe it's in the compilation of the Rvator?

At any rate, it proved to me that if you're trying to decide between the BA and older style Hartzell's, the price difference for th extra knots was negligible. People pay thousands of dollars per knot when trying to clean up aircraft, and here you get several knots for a couple hundred dollars.

Not to hijack a thread, but to hijack a thread...

I really like the Hartzell BA but really like the IO-390. Really, really like it.

I understand the BA not to have any restrictions with the counterweighted IO-360 and am hoping the same would be true with the IO-390.

I am not certain that anyone has done any testing on this combination. If so, are there any restrictions?

Anyone?

CJ

Ironflight said:

Wasn't it Randy Lervold that did some of this testing Dan? I know I read an excellent write-up, but it isn't on his site - maybe it's in the compilation of the Rvator?

Click to expand...

Yes and no. Randy did a terrific comparison of some props, but the BA wasn't around then. His comparison was mostly between the Hartzell F7666 and at least two Whirlwind props. http://www.romeolima.com/RV8/Prop.htm

Captain_John said:

I understand the BA not to have any restrictions with the counterweighted IO-360

Click to expand...

Please re-read my reply. The BA (7496 or 7497) is not approved for the counterweighted IO-360.

Ahhhhh, I see! I scanned too quickly and misinterpreted what you wrote.

Of course, there is no information regarding the 390 on that FAA hyperlink you posted, a prudent man would follow the recommendations of the comparable IO-360 until more testing has been done or go with another manufacturer.

Agreed?

CJ

I feel (and this is just me) that the rpm restrictions are somewhat arbitrary in nature. Yes there are harmonics that happen between certain RPM ranges. I know the Cardinal I fly is placarded "Avoid continous operation between 2100 and 2300 RPM", and just a smidge under 2350, I can start to feel the harmonics, and it goes away long before 2100, it seems that Hartzell has to take into account possible tach errors when they set their harmonic ranges, so the ranges end up a lot bigger for certified aircraft than it should be. I'd guess the harmonic range is actually 50 RPM or so buried in the middle of what they say to stay away from.

For my money, it's an experimental, so if you want the BA to go faster, get it, install it, feel where the vibes are, and avoid those ranges. IO-360, IO-390 shouldn't matter much...

Just my 2?

Found it!

OK, I found the article I thought I'd remembered....it was in the 2003, fifth issue of the RVator - first article.They did test the BA prop and compared it to the standard Hartzell and some of the composites.

I knew I'd read the test results somewhere!

Paul

osxuser said:

IFor my money, it's an experimental, so if you want the BA to go faster, get it, install it, feel where the vibes are, and avoid those ranges. IO-360, IO-390 shouldn't matter much...

Just my 2?

Click to expand...

Just be careful! Maybe add a safety cable to your engine like the racers are required to do.

Here is a picture of a friend's WACO UPF-7 after he lost 17" from one blade. He was out over the water at 900' and the parking lot is an empty Staten Island Ferry lot. Notice the weeds on the right gear. He picked that up from bouncing it off the berm in the background so he could make the lot. Also note the light pole he swerved around on roll-out. Man, that guy is good and lucky! Oh, and he said it didn't glide very well w/ the engine hanging down like that.

Why did he shed part of the blade though?

The NTSB said it was fatigue. No nick was noticeable on the prop stub. Apparently those solid Curtis-Reed props where known for doing that.

Eddie said he was looking over the side of the plane, felt a vibration, pulled the throttle back, looked up and noticed the cylinders were no longer visible and he was going down at a FAST rate. That was all the warning he had. Oh, he also had news (video) footage taken as they were standing around talking to the authorities. In the back ground was the plane with the engine hanging there and all of a sudden it just fell off.

Man, was he ever lucky!

I can't wait to finish the -9 so I can take him for a ride, what a great mentor he was. I learned so much from him! He has since sold this Waco UPF-7 (after he got it back in the air), his Stearman, Travelair 4000, J-3, and T-6 (Yes, he owned all five at the same time.) and bought a BIG sail boat, rented his house and retired to the Bahamas with his very lovely wife Elaine. Since he never flew the J-3 he gave me a key to the hanger and let me fly it whenever I wanted, even insisted I didn't top it off. What a great guy!

May not feel it

Caution.....In the RVator article it mentioned that the pilot would not feel most of the harmonic vibrations and that over time it caused fatigue in the prop blades.

I'm not sure it's safe to assume that just because you don't feel it that it isn't happening. I personally think that the limitations are there for a reason. Certainly there is a safety factor built in but I don't plan to go against it. JMHO.

Hartzell "BA" 7497 propeller

All,

I would like to clarify some info here. I offer this info as an engineer (I'm not a salesman) and I'm building an RV myself...

Dan is correct, the new "BA" 7497 prop is approved on the 200 Hp IO-360-( )1( ) series engines with the restriction he listed. However, although it is not listed on our TCDS yet, it is approved on the damped crankshaft -A()B6 series engines also, without any placards (read NO PLACARDS on the damped crank engines). It is also approved on the IO-390-X engine with NO PLACARDS (all -390s must have dampers according to Lycoming).

It is currently available at 74" diameter and will be available at 72" soon.

I respectfully disagree with anyone that suggests that you can ignore engine-propeller vibration approval, or restrictions and placards regarding engine-propeller compatibility.

Les Doud
Propeller Integration Engineer
Hartzell Propeller Inc.

lesdoud said:

Dan is correct, the new "BA" 7497 prop is approved on the 200 Hp IO-360-( )1( ) series engines with the restriction he listed. However, although it is not listed on our TCDS yet, it is approved on the damped crankshaft -A()B6 series engines also, without any placards (read NO PLACARDS on the damped crank engines). It is also approved on the IO-390-X engine with NO PLACARDS (all -390s must have dampers according to Lycoming).

Click to expand...

Thanks for the clarification, Les. That's great news.

lesdoud said:

All,

I would like to clarify some info here. I offer this info as an engineer (I'm not a salesman) and I'm building an RV myself...

Dan is correct, the new "BA" 7497 prop is approved on the 200 Hp IO-360-( )1( ) series engines with the restriction he listed. However, although it is not listed on our TCDS yet, it is approved on the damped crankshaft -A()B6 series engines also, without any placards (read NO PLACARDS on the damped crank engines). It is also approved on the IO-390-X engine with NO PLACARDS (all -390s must have dampers according to Lycoming).

It is currently available at 74" diameter and will be available at 72" soon.

I respectfully disagree with anyone that suggests that you can ignore engine-propeller vibration approval, or restrictions and placards regarding engine-propeller compatibility.

Les Doud
Propeller Integration Engineer
Hartzell Propeller Inc.

Click to expand...

Can't blame you for that one (given who you work for especially). And I can't say that I thought my opinion would be recieved very positively in general (hence the multiple disclaimers...) But I have seen a ton of cut-down, weird application, not placarded, etc etc... props that fly for thousands of hours with no problems. Most homebuilts don't have the advantage of being so prolific that a prop company will actually do a vibe analysis for them specifically.

I do suggest that the TBO be followed closely (6 years for most Harztells), so if fatigue does become a factor, it can be detected.

New composite BA blades for the Hartzel

At OSH this year a Hartzell rep told me they are close to starting the engine testing on composite blades with the blended airfoil. He said they would be substantially lighter and they would start approving them for use with the most popular engines.

Price would be comparable to the Aero Composite Prop.

Anyone else hear anything about this?

Ian
RV7 QB
Wings

Advanced Structural Composite II (ASCII) Blades from Hartzell

All,

Yes, Hartzell announced the new composite blades at Oshkosh this year.

The new composite blade was designed for a 3-blade assembly intended for 300 Hp applications, thus the new prop on the SR-22. However, the analysis I did showed it may work well in a 2-blade configuration on an IO-360 (from a performance standpoint). Unfortunately, we've not tested it yet on those engines. Because the aluminum -360 blades we have approved are relatively heavy (for a reason), the weight savings on those applications may be worth the effort. Right now, the weight savings it offers compared to a typical 3-blade on six-cylinder engines is approximately 12 lbs. The weight savings compared to a 2-blade -360 prop may be similar, approximately 10-12 lbs, with a potential total weight of approximately 47 lbs (not including spinner). As I said, we haven't tested it yet so I don't know how it will work from a vibration perspective.

We are always trying to improve our products for this market, trying to design-in more performance with this lowest weight possible but still comply with the Hartzell service history standards, thus the 7496 for the 180 Hp, and the slightly heavier 7497 for the 200 Hp engines. It isn't easy and costs a lot. The ASCII may be the next step, but its too early to tell. One of the things our marketing/sales guys factor-in is how many props they can sell to justify the costs of the approval process. I don't think anybody at work knows how many homebuilders would buy a new ACSII? I suppose that depends on price? What do you think the market price-point is for a new Hartzell composite prop? The new composite prop costs more than an aluminum prop to manufacture so it will be higher, no doubt, but it might be too high to justify a program just for this market. In that case we'll have to wait until OEM and STC applications cover us.

The bottom line is its too early to know if we can approve the ACSII on the 360 engine, especially since they come in so many flavors, 180 Hp, 200 Hp, damped crank, undamped crank, LSE, LASAR, FADEC, Superior, ECI, high CR pistons, etc,; there is at least three vibration surveys to accomplish. Only time and market demand will determine if and when we can offer the ACSII to you all.

Les Doud
Propeller Integration Engineer
Hartzell Propeller Inc.

Les,

I just want to say thanks for monitoring these forums and posting the info you did. It's terrific having folks representing mfrs to keep us in line, make sure we're speaking the truth, and give us insight into "real" developments. Your input is highly valued...so thanks.

Ditto waht Dan said above. Thanks for the input. It is very helpful.

Propeller Selection

I thank you also Les. Ya godda love this group. Ask a question and someone who knows will usually jump in and answer. If the answer is wrong the jumper quickly becomes the jumpee.

Les you wrote:

I suppose that depends on price?

I will happily pay more for a 10 pound lighter and 5 knot faster prop up to a limit.

What do you think the market price-point is for a new Hartzell composite prop?

For me if the Hartzell price for a two blade ASCII comes in under Aero Composite put one on the truck. I would get a little huffy if a big outfit like Hartzell charged lots more than the little guy.

Couple more questions for you Les if you don?t mind:
1. Is the new ASCII prop a blended airfoil?
2. Is the aircraft performance improved with the new ASCII blades?

Paul those Rvators are not available on line are they? If not will you summarize for us the result of the flight tests of the various props in the 2003 article? I spoke with Dick Martin at OSH who said his Aero Composite prop was way faster and lighter than his Hartzell. I never thought to ask if he was comparing the Aero Composite to the new BA Hartzell or not.
Or let me put this question another way;
Does anyone know which is fastest?
the WW RV200,
the Aero Composite,
the Hartzell C2YR-1BFP/F74972

(yes I studied http://www.romeolima.com/RV8/Prop.htm which is a good read)

My pleasure folks

I will get more from these forums than I could possibly give so it's my pleasure if I can contribute something.

I would love to say, "sure, 5 more knots, no problem..." but I can't. Analytically our new props are already in the 87% efficiency range, much more than that would be a very costly iterative process and require enormous patience. The difference between 87% and 90% (rarely obtained) is only a few lbs of thrust. Our current aluminum designs for the -360 are now pushing the limits of our blade forgings. It would require a larger or new forging (= more $) to squeeze-out a little more performance in aluminum, and it wouldn't be much. It probably is not a good knots/$ ratio in my own opinion. Keep in mind that performance is only one factor in blade design. Sometimes other factors limit us from improving performance. Composite designs are not constrained by a forging so they give us a little more freedom. However, composite blades have their own unique hurdles too. Probably the best benefits of a composite blade are reduced weight and from what I'm told, smoothness. It's possible that we would design a new 2-blade composite specifically for a high-speed, -360 powered airplane, but that probably isn't going to happen within the next year. Until then, we'll probably test what we have and see how it works. I'll do my best to keep you updated on this list so please don't call every week asking "is it ready yet?"

Yes, all of our new designs are "blended airfoil" whether aluminum or composite. "Blended airfoil" refers more to the process of blade design rather than a specific airfoil or blade.

I won't comment, throw stones at, or speculate about any competitors; I prefer to let you folks decide what is best.

Regarding cost, that is why we developed the new composite process, to take cost out. I hope its affordable but we'll have to wait and see.

I've been at Hartzell almost eight years and I've come to realize that a significant portion of propeller price goes towards supporting the product. Manufacturing aside, it takes a small army to support the props that are already in the field, let alone what we'll sell in the future. In fact, I was just working on an issue with 1958 Beech Travel Air props to give you some idea... There is a platoon of product support folks to answer the phones and troubleshoot customer problems, a platoon of engineers to work service difficulties when they arise, a platoon of folks to support parts sales and maintain a network of service shops, a platoon to write and maintain all of the tech pubs, a full time position to support accident investigations, etc. etc. When you buy a prop you're paying for a lot more than the materials and manufacturing labor.

In closing, I'll try to answer the question "which prop?" My advice is to purchase what Vans recommends and/or endorses. It seems you can't go wrong if you do that, and it should be safe too. Which one is faster? We rely on Vans to tell us that. Some individuals have done a good job of performance comparisons and publicly-documented their results fairly; I think we compare favorably. In the end if it means you don't buy a Hartzell, so be it, you'll probably be happy if Vans likes it and their endorsement assures some level of safety, which is most important to me.

Les

Propeller Selection

Good answers Les
Thanks again

Hey Les?

Can I take you off line for a discussion on 6 cyl props and a glass airplane?

If so, drop me an email at aadamson at highrf dot com. I've got a couple of quick questions on the composites, etc?

Thanks

prop performance

Here are some results of prop testing...

http://lazy8.net/proptest.htm

These are just one person's experiences.


Les --

First, as others have said, thank you for taking the time to contribute.

Second, you have me all excited about the possibility of going from 87% to 90% efficiency...that would translate to 3.4 mph gain on a 200 mph airplane!!

Please tell marketing they would sell at least one! To have the performance and weight savings of a compsite prop with the very complete testing done by Hartzell would do it for me!

John

Les why cetrtify

Les

Thanks for your insight and information.

To answer one of your questions, I would love to buy a Hartzell, but unfortunately the weight penalty for my -8 is way too much. So I will have to go elsewhere. But from all the builders, and especailly -8 builders I have spoken with I believe there would definitely be a good sized market for a lighter "smoother" prop, especially with the Hartzell name on it.

My question is why does Hartzell feel the need to certify? The experimental market does not require certification. I am sure most will agree, that if Hartzell applies the same company standards to design and manufacturing on all their props that whether or not it is certified would not make much difference, except in the wallet. I would think that besides the cost savings, it would benefit Hartzell to have alot of props flying and gathering data, which would increase product knowledge and decrease testing cost if/when Hartzell decided to certify the prop.

Stones and props

lesdoud said:

Yes, all of our new designs are "blended airfoil" whether aluminum or composite. "Blended airfoil" refers more to the process of blade design rather than a specific airfoil or blade.

I won't comment, throw stones at, or speculate about any competitors; I prefer to let you folks decide what is best.

Regarding cost, that is why we developed the new composite process, to take cost out. I hope its affordable but we'll have to wait and see.Les

Click to expand...

I don't mind throwing stones. Thanks for the input Les. I don't work for Harzell, but the Hartzell BA prop is the best choice in my opinion.

Somw one made an issue of weight and a basis for going with a composite prop.

First consider this, any composite prop is likely to cost more, a lot more. Overhaul? More about that below.

If anyone makes a composite prop approaching the thinness of a metal prop, such as aerocomposites, they tend to be very stiff and not as "smooth" like say the wood core props MT makes. The down side of MT's wood core props, as nice as their props are, is they are thicker and tend to be slower at the speeds we fly. It is just engineering. Time and time again the metal two blade Hartzells, BA or even the older HC-C2YK/F7666 have proven to be faster than any other props, even the high tech aerocomposites and whirlwind RV prop, the three bladed whirl winds and MT's are slower still. Why, thickness is part of the reason in my opinion and three blades are less efficients.

Most important to me is maintenance. A minor nick in a metal prop can be handled on the ramp, with the prop still on the plane with careful blending (with a fine spoon file). A delamination composite prop or dented erosion strip means removing the prop, disassembly and in many (most) cases shipping to the manufacture. I can't stress how important the customer support and wide availability of parts and service is. Some of the "boutique" props can ONLY be repaired at the manufacture and that may be outside of the USA.

Before the you get angry at me, please note I did not say anything bad about the any prop, just facts, mostly about the draw back of composites in prop construction. Second is you can't deny the support system of Hartzell is better than any other of the experimental prop brands. The composites do have things to offer, like smoother "feel" as some report and lighter weight, but they cost more to buy and maintain.

Price a complete overhaul on your composite prop and get it in writing before you buy a new prop. Just saying. Know what you are getting. Van replace an old MT with a Hartzell. It was not because they did not like the MT, but they did not want to spend the money to overhaul the MT, which was about what a new Hartzell cost. Plus they did not want to wait the long turn around time to send it to Germany to be overhauled. Most can get their Hartzell overhauled in a week locally at an approved shop in a short time.

I find a well balanced engine and Hartzell prop run at the "sweat" RPM is very smooth. The price and support makes it a no brainier for me and I think most. I clearly see a desire and need for some to use the composite prop, but most RV's would be best severed by a Hartzell in my opinion.

The weight issue? I never built a RV-8 but my RV-7 needs all the weight on the nose I can get with a O-360 (180HP) engine.

I have a F7666 only because I bought it use and before the BA prop was around. The BA prop is by far the best thing going hands down, IMHO.

George did I understand your correctly?

George,

I might have read something into your post that you may not have meant? But you worded it kinda strange.

Les - DOES work for Hartzell, Hartzell announced a new composite prop at OSH - hence Les' comments about composites and how good Hartzell is getting them (rivaling metal).

I guess I just read your note as if you were trying to talk to Les as if he were a builder (oh, btw, which he is, but he just happens to be in engineering at Hartzell as well) and espouse the virtues of metal *over* Composites. Somehow, with the inside info that Les has access too, I suspect he knows exactly how good one or the other is for a given application.

Sorry, if I miss read your post, but it just struck me as odd the way it was worded...

Oh, btw, to back up your claims. Last year at Reno, there was a Gaggle of Lancair Legacys in the Sports Class finals (sliver race). all of them but one was running a Hartzell, he was running an MT with AeroComposite Blades.

For the Final, they quickly pulled another hartzell off of the factory demo and put it on the last airplane (the one with the composite prop). That airplane had been about 10mph slower all day in the qualifications. You can go look at the times on line, but changing out that prop, pulled that airplane up with the others and gained it back those 10mph.

On the Maint topic. Can I offer another perspective? On a metal prop, it's not a matter of if, but when you'll have to purchase a new blade. They just wear out over time. The largest challenge beng "nicks and dings". A Composite by contrast will most likely be much cheaper to repair and may *never* require full replacement, if you get a large nick or ding in it.

Goods and bads on both sides I suppose.

aadamson said:

On the Maint topic. Can I offer another perspective? On a metal prop, it's not a matter of if, but when you'll have to purchase a new blade. They just wear out over time. Either errosion or otherwise. At Composite by contrast will most likely be much cheaper to repair and may *never* require full replacement, especially due to errosion.

Goods and bads on both sides I suppose.

Click to expand...

Ususally 20+ years and four overhauls down the road. Not that big a deal after that amount of time.

I respectfully could not disagree more

aadamson said:

George,

I might have read something into your post that you may not have meant? But you worded it kinda strange.

I guess I just read your note as if you were trying to talk to Les as if he were a builder (oh, btw, which he is, but he just happens to be in engineering at Hartzell as well) and espouse the virtues of metal *over* Composites. Somehow, with the inside info that Les has access too, I suspect he knows exactly how good one or the other is for a given application.

Sorry, if I miss read your post, but it just struck me as odd the way it was worded...

Oh, btw, to back up your claims. Last year at Reno, there was a Gaggle of Lancair Legacys in the Sports Class finals (sliver race). all of them but one was running a Hartzell, he was running and MT with AeroComposite Blades.

For the Final, they quickly pulled another Hartzell off of the factory demo and put it on the last airplane. That airplane had been about 10mph slower all day in the qualifications.

On the Maint topic. Can I offer another perspective? On a metal prop, it's not a matter of if, but when you'll have to purchase a new blade. They just wear out over time. Either errosion or otherwise. At Composite by contrast will most likely be much cheaper to repair and may *never* require full replacement, especially due to errosion.

Goods and bads on both sides I suppose.

Click to expand...

No apologies necessary. I know Les works for Hartzell. He said he would not throw stones at the competition, so I said I'll do it. My comments where regarding existing composite props not Hartzell. I don't know Les personally, but I have talked to Hartzell engineering on many occasions since I have an engineering degree and speak geek (sorry Les)

I did not get that Les was "espousing" composites over metal at all. I guess that's what you wanted to read into it.

You need to actually read what Les said about the ASC-II:
http://www.vansairforce.com/community/showthread.php?p=66969#post66969

Back to the thread for a second, the "BA" (metal) Hartzell is hands down best value and performance for a RV with the best support. Trust me.

Hartzell's announcement of the new ASC-II composite prop structure is NOT a wholesale endorsement of composite props or the end of metal props, sorry. You are reading way more into it. If they make an ASC-II prop for the RV some day, great, but right now they are for King Airs.

My "oddly worded" comments are my opinions, not designed to influence Hartzell, Les or you. It's info and conclusions from my prop research that the other 4,000 RV builders may enjoy, which may not apply to Lancair builders or Reno racers, no offense.

Hartzell has made and sold composite props for years by the way, one is the claw, for aerobatics and is very expensive. They also make commercial composite props. I wish Hartzell the best of luck with the ASC-II process. As Les said, we shall see.

My guess, the ASC-II will be too expensive for the homebuilt market, and the performance will be no better than the existing metal BA prop for RV's. You can quote me. Hartzell says it's better than existing "thick" (fat) composite props. I believe that. If Hartzell makes a ASC-II "BA" prop for RV's that performs better than the existing metal "BA" RV prop, I'll publicly state Lancairs and composite planes are better than metal. Never happen.



RENO?
"For the Final, they quickly pulled another Hartzell off of the factory demo and put it on the last airplane"

Sorry, no offense but you're leaving off too much info. What Hartzell? What composite prop? What airplane? What speed? There is more to the story, but I'm 100% sure it does not apply to RV'ers.

I'm not going to argue Reno data. You say Sportsman silver class has many/mostly composite props in it? OK, that's cool to know but has little to do with RV's and proves nothing.

Racers use composites props not for speed but in part because they can't find a tested metal prop for their highly modified engines IMHO. Many use the metal Hartzell's and go fast. Hartzell does an excellent job but can't test every homebuilder / racers engine who does weird things (cams, compression, exhaust, electronic ignition). Metal prop's do need to be tested on every engine config they are mounted.

Performance - You demand I need to backup my claims, that the Hartzell "BA" prop is faster than any other c/s prop for a Lycoming 4 banger on a RV, here is the backup data you requested. (click, twice, read it and weep )



The only thing faster was the METAL Sensenich fixed pitch prop at that condition, typical cruise condition. It's been shown time and again the "BA " prop is faster, even against a later "new" MT prop. Rocket builder/pilots with 540 cu-in Lycs also find the Hartzell faster than the composite new MT by 5-8 MPH. You are WRONG. The fastest c/s prop for a RV's (and Rockets) is the Hartzell. btw prove I'm wrong.



"On the Maint topic. Can I offer another perspective? On a metal prop, it's not a matter of if, but when you'll have to purchase a new blade. They just wear out over time. Either erosion or otherwise. At Composite by contrast will most likely be much cheaper to repair and may *never* require full replacement, especially due to erosion."

I totally and respectfully disagree with everything you stated in the above Par. about maintenance, 100%. Again you got it 180 degrees backwards IMHO. Most metal props will out live the pilot with indefinite fatigue life (withstanding life limit for the F7666 on engines w/ HC piston/EI). Metal Hartzell's can go forever, in theory. What is the service life? (Les?) Yes, they "wear" or erode below dimension limits (thickness or chord) at some point (10k - 20,000 hours?).

If you fly ANY prop fast in heavy rain or out of gravel strips, composite props, even with their erosion strips, are subject to the wear, tear and damage. Erosion strip delimitation is a big issue on all the composite props. If Hartzell says they can refinish the new ASC-II forever, it's a great sales pitch. How much is that "re-finish" going to cost? Ouch

What is the high time GA composite prop (AeroComposites, MT, Whirlwind)? As far as I can tell they just scrap many damaged and high time blades and sell new ones. It cost more to do NDT (non-destructive testing) and repair than just build new ones.

We'll have to agree to disagree again. Composite blades are NOT forever props. Despite Hartzell's "press release" they last forever by refinishing them, no offense Les, true in theory but lets see. Even if true, I don't see it works in favor of low utilization personal flying. Purchase price? Drop a ASC-II prop into a non-warrantied pot-hole, there goes forever. Besides forever is longer than I need. Does Hartzell offer a "lifetime" guarantee?



There's no doubt in my mind at this time, average cost of composite prop ownership is greater, short or long term, than a metal one. There's no need to soft sell or spin this fact. They cost more to manufacture, buy and repair. I guess you don't get the RVator news letter. Bottom line the MT overhaul was over double what the Hartzell overhaul, which only took days to do, not weeks (or months) the MT would take. So the MT was removed from the demo plane for cost and service reasons. The MT was also slower. What's a ASC-II overhaul cost?

Any way sorry if I confused you, but AT THIS time composites props cost more, perform less and service is more expensive and spotty. Will ASC-II change this? Questions? Comments? Corrections? For now the answer is the "BA" prop for most.

whirlwind propellers

I have a WW 200RV on my IO-360M1B, dual electronic ignition, RV-8. I have 175h on the prop and have found the Yahoo group dedicated to Whirlwind to be useful for understanding some of the technical issues.

Hate to advocate a group *outside* of Doug's site, but since there is a good amount of data there and there is no way to move it all over here, I hope he will not be offended

http://groups.yahoo.com/group/whirlwindpropellers

Jon Weiswasser
RV-8, 250h, N898JW
Montclair, NJ

gmcjetpilot said:

RENO?
"For the Final, they quickly pulled another Hartzell off of the factory demo and put it on the last airplane"

Sorry, no offense but you're leaving off too much info. What Hartzell? What composite prop? What airplane? What speed? There is more to the story, but I'm 100% sure it does not apply to RV'ers.

I'm not going to argue Reno data. You say Sportsman silver class has many/mostly composite props in it? OK, that's cool to know but has little to do with RV's and proves nothing.

Click to expand...

Hmm, well, besides my typos, which I'll have to go correct. I thought I gave most of that. But incase I didn't I'll do it again..

Reno 2005 National Airrace Championships - ala Reno Air Races.
The Sportsman class is made up of just about everything. There are Lancair Legacys, Nemisis NXTs, Thunder Mustangs, HRII's, F1 Rockets, Questairs, etc. I think last year there was even an RV in that mix.
The Hartzell prop is a stock 3 blade for the Continental IO550, similar prop as to what you'd put on a Super 7 or Super 8
The composite was a 3 Blade MT with AeroComposite blades, again similar to what you'd put on a Super 7 or Super 8.
Oh and lastly the speeds were 280mph.

I guess perhaps you missed my point... Even tho I believe I said. it...I was attempting to "support" your position of the metal blades (props) being faster than the composite ones. I used the above example as a case in point. I certainly wasn't attempting to *prove* anything, simply offer the example to support your position.

Hope that clears that up.

Originally Posted by lesdoud: Dan is correct, the new "BA" 7497 prop is approved on the 200 Hp IO-360-( )1( ) series engines with the restriction he listed. However, although it is not listed on our TCDS yet, it is approved on the damped crankshaft -A()B6 series engines also, without any placards (read NO PLACARDS on the damped crank engines). It is also approved on the IO-390-X engine with NO PLACARDS (all -390s must have dampers according to Lycoming).

Click to expand...

Les;

I'm a little confused on the blended airfoil prop restrictions? I see your comment above about no restrictions on the 7497 prop being dependent, I think, on the damped crank. But, I see this quote for the 7496 prop at : http://www.hartzellprop.com/kitplane/kitplanes.asp?kit=VAN003&manufacturer=Vans:

From Hartzell: Hartzell Propeller Model HC-C2YR-1BFP/F7496 is vibrationally approved when mounted on Superior Air Parts model O-360-B1A2 and IO-360-B1A2 engines rated at 180HP at 2700 RPM with magneto ignition and installed in Van's Model RV-6A and similar single engine tractor aircraft. There are no operating restrictions.

Click to expand...

The Superior engine is not a damped crank, right? Another question is whether a IO-360, 180 HP with a damped crank would be free of operating restrictions when using either 7496 or 7497 prop? (If a magneto ignition is used?)

MT aluminum 2 blade

I haven't seen a lot of info about the aluminum bladed MT 2 blade prop--it's not the one offered on Vans site but is available here: http://www.lessdrag.com. There is a spreadsheet showing performance (speed only) testing done on a O-360 engine mounted on an RV-6A comparing the composite 2 and 3 blade MTs and the Hartzell HC-C2YK-ABF/F7666A-4 to the aluminum MT. Aluminum to aluminum, the MT is slower at lower DA than the hartzell, but gets slightly faster overall at higher DA. The interesting claim is "No Midrange RPM restriction on any Lycoming 360 engine with this propeller."

I don't know how long this prop has been available--I don't see a lot of reports from people flying behind it. Any opinions? Price is about $500 more than the hartzell BA from Vans.

Mike

May because it's not a good prop for a RV

mandm1516 said:

I haven't seen a lot of info about the aluminum bladed MT 2 blade prop--it's not the one offered on Vans site but is available here: http://www.lessdrag.com. There is a spreadsheet showing performance (speed only) testing done on a O-360 engine mounted on an RV-6A comparing the composite 2 and 3 blade MTs and the Hartzell HC-C2YK-ABF/F7666A-4 to the aluminum MT. Aluminum to aluminum, the MT is slower at lower DA than the Hartzell, but gets slightly faster overall at higher DA. The interesting claim is "No Midrange RPM restriction on any Lycoming 360 engine with this propeller."

I don't know how long this prop has been available--I don't see a lot of reports from people flying behind it. Any opinions? Price is about $500 more than the Hartzell BA from Vans.

Mike

Click to expand...

First of all this prop has not been tested on modified Lycoming's, such as high compression pistons, electronic ignition. If it has no restrictions I would like to see the type certificate for the prop and what engine and aircraft it was approved on. Second, this prop was originally made for much slower planes than a RV, there for it's not ideal for a RV. It is a generic prop. Third the test was against a Hartzell C2YK/F7666 not the newer "BA" Hartzell prop, which is optimized for faster RV's. Forth, it cost more than a Hartzell $6,400 (sale price) + shipping from Germany. Normal price $7,800. The Hartzell is $800 cheaper and may be $1,300 cheaper including shipping.

Last and most important it has lower performance. If you plot the data on this web site, it has so much scatter, inconsistencies and just plane wrong-ness, it's useless. I have talked to this Gent and pointed out the errors, but he is in denial. Here is a plot of the data, and you tell me what is wrong: (click once to open thumbnail jpg images):

Metal MT 2-blade Vs. Hartzell C2YH/F7666


Top two graphs summary of 2-blade metal MT-12 and Hartzell C2YK/F766.
Bottom three graphs are summary of all Props Lessdrag tested (@ 2500', 7500' and 12500').
(3-blade composite MT-12, 2-blade metal and composite MT-15, Hartzell C2YK/F7666)


I am not trying to bad mouth MT, clearly this is ones dealers idea to test several props over many days and conditions to show how great his product is. He tried to test 4 props, 3 MT props and 1 Hartzell, at 5 altitudes and 4 RPM's on the same plane. Although ambitious and no matter how well intentioned, it's seriously flawed data. All the crossing lines, change in slope and reversals shows the data is invalid. The data should be smooth and consistent not wild oscillations. Jim the owner is a nice guy I hear, but he makes claims I find hard to believe and presents data that is impossible. If he would have picked one density altitude or two, one RPM and listed manifold pressure, temps and method of measurement he would have got better results and I would have more confidence.

Jim is under the belief that a prop with lower efficency becomes much more efficient at certain RPM's and altitudes, well beyond what prop theory and classical analysis says is possible. There is truth to that. Lower RPM increases efficency for any prop. Altitude has simular affects. However the affect is predicatable and follows a trend. There will be no quantum leaps in performance one way or the other. You just don't see 6 mph changes for very small changes in RPM or altitude. Than adding to the mystery, his data shows the lost speed goes back and forth with RPM or altitude for the same prop? There are either errors in recording data, methodology, technique or environmental conditions in play. No doubt this test took place over many days and conditions.

Bottom line no one would want a MT metal two blade prop when you can get a Hartzell "BA" prop that performs better, cost less and has no RPM range restrictions. What small restiriction there may be on some engines, are inconsequential to normal operation (single power points out side normal operating settings). MT would love to sell a prop they made for other certified application to RV's, but the prop is not ideal for our application. Where the "BA" prop was optimized for out application and is clear by Van's data, Randy's data and Lazy8.net data.




Unfortunately this is not the first time Jim has made claims I disagree with. One claim I recall he made was about the drag of one comm antenna, which would cost massive loss in speed. In fact one bent whip external comm antenna cost you about 1/4th to 1/3rd mph at 200 mph at worst. BTW he sells some kind of hidden tail antenna.

Look let me trumpet Hartzell's horn, there's no other prop company that supports and designs C/S props for our RV's. Sensenich does a great job with the fixed props BTW. The "BA" prop is a direct effort to make a prop for us RV'ers. MT and others make generic props that where made for other applications and are marketed to us. They are not bad, just not optimized. Also no other company but Hartzell that I know of has gone to the effort to test "experimental" engines, engines with high compression pistons or electronic ignition with their prop.

When a MT dealer says there is no RPM restriction and does not state what engine it does not mean anything. If you put HC pistons/EI on your engine than all bets are off.

To Hartzells credit they actually test. Everyone else is guessing. Unless I see it in writing I would not believe a manufactures claim of performance or RPM restrictions. There attitude is its going on an experimental, they will buy anything. Hartzell actually supports, designs, test props for RV's as a target market, not a side line to their certified props.

Thank goodness for Van's, Randy Lervold and others who do careful, unbiased prop comparisons for us. The lessdrag.com data is not good data and useless.

Props are one of those areas full of mystery, rumor and urban legend. Since it is hard to compare and it is so dependant on the airframe it is rip for hearsay and rumors. It is engineering, aerodynamics, science and a little art. The fact is we are talking abut a few percent difference and the airframe and engine are key to the prop design. One size does not fit all.

In the case of the older Hartzell C2YK/F7666 originally designed for the Mooney and Piper Arrow high pref single engine retracts. The prop is still pretty good, even after 40 years. There've improvements through the life of this prop, but in general they got it right the first time. With that said Hartzell was able to even improve on this good prop that still is faster than most "high tech" props. Hartzell optimized the "BA" prop for the RV. Hartzell got 3.5 mph more out of the "BA" prop. That is not trivial; it's very hard to get even one or two percent better efficency. That is why I question any "other" data where one simular prop has a huge edge of like 10%.

For some reason people want to express their individuality with their prop and not use what everyone else has. I get that. Three blades are sexy. The composite props are not boring Hartzell grey and painted bright white or black. Unfortunately on a RV three blades means going slower. If you want to paint your Hartzell any color you want: http://www.americanpropeller.com/DESIGNERsamples.htm

Save your individuality for the instrument panel or your planes paint job and leave the prop to Hartzell and buy a "BA" prop if you are in the market for a constant speed prop. For fixed props Sensenich. If you don't already have enough reasons to buy, they are USA made! What else can you say.

MT untested?

When a MT dealer says there is no RPM restriction and does not state what engine it does not mean anything. If you put HC pistons/EI on your engine than all bets are off.

To Hartzells credit they actually test. Everyone else is guessing.

That's news to me. I am examining the three bladed MT (MT-12-B/183-59b) as an option and have been in extensive discussions with MT regarding testing with EI, and the imposition of RPM restrictions under such conditions. They are making available to me vibration surveys and other testing data performed with the IO-360 and EI and claim (in writing) that their propeller can be used safely without RPM restrictions with electronic ignition on an RV. Happy to share paperwork.

Jon Weiswasser
RV-8, WW200RV
Montclair, NJ

I honestly would like to see it in writing

jonweisw said:

When a MT dealer says there is no RPM restriction and does not state what engine it does not mean anything. If you put HC pistons/EI on your engine than all bets are off.

To Hartzells credit they actually test. Everyone else is guessing.

That's news to me. I am examining the three bladed MT (MT-12-B/183-59b) as an option and have been in extensive discussions with MT regarding testing with EI, and the imposition of RPM restrictions under such conditions. They are making available to me vibration surveys and other testing data performed with the IO-360 and EI and claim (in writing) that their propeller can be used safely without RPM restrictions with electronic ignition on an RV. Happy to share paperwork.

Jon Weiswasser
RV-8, WW200RV
Montclair, NJ

Click to expand...

Jon I would love to see that data. When Hartzell test they release the data or written comments. I am glad to hear they checked it out and they are supplying you with data.

I understand that MT is in Germany and there may be a some language difference. It's not like you can call MT engineering, like you can with Hartzell and chat with them in English. Most of the MT folks in the USA are just dealers and salesmen, not technical. If you have test data great.

Composite props are different. When I said testing for RPM restrictions on modified engines, I was spacifically talking about the MT-15 metal two blade in particular. I would like to see it in writing, that the MT-15 metal 2-blade prop has been tested with high compression piston and EI.

I have asked and asked but never got more than talk. Granted metal props are more critical for harmonics and must be tested, but composites should be tested as well, even though they are naturally dampened by the wood core; I suspect the MT wood core props are very resistance to harmonics to a much greater degree than metal or even pure carbon props.

Still test data with modified engines would be great to see. I know they are often STC'ed on slow planes like the Husky "Cub" (two blade) and faster planes like the Piper Aerostar (four blade), however I assume those are stock engines.

George,

Thanks for your reply. I'm pretty new to this forum and am trying to learn as much as I can--you're a great resource. I've been about 99% sold on the Hartzell BA for a while but the 1% is due to restrictions. Having not flown an RV (yet) I don't know practically what these restrictions mean. So the word restriction is equated to possible limitations of the fun to be had in an RV--or at least something else to think about when flying. So my question is how restrictive are the restrictions? Vans web site says for IO-360 EI engines, no manifold pressure above 22" with rpms below 2350, and reduce rpms to below 2600 as soon as practical after takeoff. Not from an engineering standpoint, just from the pilot standpoint, what do these restrictions really mean/flying hour to flying hour how often do adjustments have to be made to accomodate them?

Thanks again,

Mike

You all make some great points

You all make some good points and ask some good questions.

Regarding why certify for experimentals? That is an excellent question. Like many things in life, there are pros and cons. I could make an argument either way but Hartzell's underlying policy is not to sell a prop until we're sure it is safe. That being said, certifying props is a little different than certifying airplanes; you can prove it to yourself by comparing the thickness of Part 23 to Part 35. For aluminum blades, it comes down to the testing required to verify the prop is safe on the engine we say it will be safe on. Because our hub and blade retention system have a known service history, are well documented, and are already certified for known HP/RPM combinations, a vibration survey of the blades is the last item to verify the prop is compatible with the engine. Once that is done the certification process becomes more of a paperwork issue (since we are a DOA, we have the unique ability to self-certify). We have sold "experimental" props (marked with X's) before the paperwork process is complete but only after the vibration survey shows everything is Ok. Selling X-props is rare and I doubt the price is any different.

Composite blades are a bit different. They not only require a vibration survey but also require what the FAA calls "special conditions." I might be mistaken but I believe we were the guinea pigs for structural composite blades on recip engines and the associated special conditions? The special conditions are usually posted in NPRMs (publicly available) and are made a final rule for each type of composite blade. The special conditions would include such things as unique fatigue testing of the blade components, double CF/spin-rig testing to make sure all the parts stay on, verification of the bonding/molding process, birdstrike and lightning strike testing (an improperly designed composite blade when struck by lightning looks like a loaded cigar after it explodes). All of this testing is usually done a few times during design & development to make sure the blade is safe; the tests are a smart thing to do regardless if you are certifying or not. The final paperwork steps to certify aren't a huge task when looking at the entire project.

The bottom line, all it takes is one failure (whether experimental or not) to ruin your whole day, so we do everything we can to prevent such an event. Just because its experimental doesn't mean somebody won't sue. For example, if you sell 50 props before all the testing is complete and then find out later you have an issue, it takes enormous effort and expense to fix those 50 props, probably more $ than it costs to complete all the testing up-front.

Regarding maintenance of composite blades, that is a good point. Typically the life-cycle cost of structural composite blades can be shown to be lower than aluminum. As stated in an earlier post, the aluminum blade can erode and require replacement. A composite blade can be repaired and the erosion shield (fancy term for hard-alloy leading edge) can be replaced, thus a composite blade could last a long, long time. Our Beech 1900D blades prove the service life of composite blades can be very long. However, unless you're flying your RV a lot, I wonder how the cost comparison stacks up? Unless a big rock whacks your aluminum prop, I wonder if a typical RV owner will go through blades fast enough to justify his decision solely based life-cycle costs? Granted, the composite erosion shield is much less likely to suffer rock damage (its' really, really hard), it still requires some special attention (= $) when it does get whacked. This is why some like aluminum blades, all you might need is a good set of files... Don't forget the paint for a corrosion barrier! This brings me back to my earlier statement, the near-term benefits of a composite blade for RVers are more likely to be lower weight and smoother operation.

Regarding Sport Class racing, there can be unique conditions where a metal blade is better (in my opinion). Due to the nature of composite construction, a composite blade is thicker in the areas of the blade that can impact performance at race conditions. I suppose you all will make me eat my words when a composite blade wins at Reno? Its possible a composite prop could win if somebody shows-up with the right combination of diameter and RPM. Unfortunately most of the racers want to turn their engines at Warp 9 and the thickness profile of composite blades starts to play. By the way, please don?t turn your props at higher RPM than what its rate for.

I hope we can make a 2-blade composite that appeals to at least some RVers? We're certainly trying hard to make it more affordable and as light as possible. Until then, I think the aluminum prop compares favorably when all things are considered. When you use the correct engine mount isolators and have the prop dynamically balanced, the installation should be smooth enough for the most discriminating.

Les Doud

Some more history

The 7496 and 7497 are my designs so I may be able to add a little history to the discussion. First of all, I'm glad this forum is discussing the restrictions and/or placards, awareness of placards results in safer operation. The design objectives of these new blades were to eliminate the placards (or at least minimize their impact), improve performance, and minimize the weight, not all in that order becase they are all related. It wasn't easy and sometimes very frustrating. The design series actually started with the 7494X (which never made it passed the experimental stage), then the 7495X and 7495X1 (which was approved on the Diamond DA 40, although with shot-peening). The Diamond DA 40 came along while I was engaged in this effort. Then there is the 7495X2 (which became the 7496), the 7495X3 (which finally became the 7497), and the 7495X4 and X5 which was my attempt to "back door" the mid-range RPM issues (needless to say they didn't pan-out). Trust me, there were folks at work that were loosing patience with me while we tried to approve something that achieved some success with all three design objectives. Unfortunately, there isn't "more than one way to skin a cat" when designing for this application. The 7497 ended-up being thicker and heavier than I would have liked, which also limits performance to some extent.

The other design criteria I forgot to mention is the blade must fit in a reasonably sized forging, thus keeping costs down. I think the 7496 and 7497 are the best "balance" we can achieve at this point in time.

Correction! We approved the 7496 on the Superior engine with different placards from the standard Lycoming parallel valve -360, but that demonstrates how different each -360 application can be. The 7495S on the Diamond is approved without placards but that is a 180 Hp engine with a "hybrid" 200 Hp induction system that (favorably) affects torsional vibration.

In short, there are so many variations of engine configurations that we can't test them all, I wish we could but it just isn't cost effective. When in doubt about your engine configuration, call and we'll let you know. However, be prepared to hear "its not approved" if you are using 10:1 pistons... If you are deciding what engine to use, please use what we tested and approved if you want to use a Hartzell!

Will we rest on the performance of the "BA" prop? Not as long as I'm around! There could be small improvements but they'll cost more and take some time to convince everybody it is a good idea. Then there is the time to test it and determine if it does what we designed it do. Additionally, we are always trying to make improvements and design new products so rest assured, we're not sitting on our thumbs here in the cornfields of Ohio...

By the way, for everyone wanting to know, I was testing a 7497 prop yesterday and I put it on the scales after flying it. The weight is 58.3 lbs. Ouch! I weighed a new, "dry" prop several months ago at 58.1 lbs so the std. dev. seems to be around .2 lbs. I believe the weight of the 7496 is approx 57.4 lbs. Please, no flaming arrows! I know 58 lbs is a lot but I won't apologize for the weight because that is what it takes to eliminate or minimize the placards; I know, I've been there, done that... It took seven designs and numerous tests to approve three props on a handful of engine configurations. We know there are competitors out there and I encourage all of them to spend the money and time to design and approve propellers on all the -360 engines .

I hope our new composite blades will make my job easier to design a prop on most -360 engines! But then there is that cost hurdle...

Like I said, when in doubt or if you have any questions, don't hesitate to call or e-mail. If you're ever flying through the Dayton area, PLEASE make a fuel stop at Hartzell Field (I17) and call, I'll give you a tour and share my sandwich. The Air Force Museum is a 40 minute drive from our facility if you need more encouragement.

Les Doud
937-778-4262
[email protected]

Wow!

Les,

I just want to add my thanks to those that have come before for participating here, and taking the time to share your knowledge and history. I feel like I should be sitting cross-legged in front of the computer hearing the story directly from the guy that designed my prop - that is very rare! I get to here about the design of a lot of aerospace hardware from the design teams that build them, but it is so different when we are talking about something I personally chose to own.

Let's see, I've put 230 hours on my BA prop in a little less than a year.....OK, you've got a few years to perfect that composite wonder that I can replace it with when it needs overhaul!

Paul

Fun when flying with RPM restrictions

First off, thanks to Mr Doud, for taking the time to pound the key board on our behalf. It's great to hear the whole story directly from a Hartzell engineer, rather than bits and pieces of flight line hearsay.

A comment on flying with restrictions. I've got approx 2500 hours flying a 1966 vintage certified retract with a Hartzell and an O-360 that has the RPM restricted between 2000-2250 RPM, at any MP setting. What's it like? It's easy. Once I trained myself to keep out of the area (took approx 5 hours), it's natural. And this ship does not have a wing leveller or AP, and I hand fly it IFR. If I can do it, anyone can. Have there been times I wish I could put the cruise RPM somewhere other than 1800-1900 and 2300-2600? Once in awhile, but the engine really likes 2300 and 2500 RPM. At 2300/21" below 8,000" I have gotten just a shade below 9GPH. Above 11,000 using 2500 and WOT I see around 9GPH, and at 11,000' and 2300/18.5" I see 8.3GPH. It has been easy and cost effective to maintain.

For my RV-8, $5800 thru Van for Hartzell BA, (with restrictions) is still better than $11,000 without restrictions (or certification) for an Aerocomposites. The difference pays for a ton of gas, not to mention peace of mind that the blades have had a thorough harmonic screening and the manufacturing is held to tight process and configuration management. I'll bolt and safety it, and go fly. No worries.

Art in Asheville
N666AT RV-8 Finishing
IO-360 Angle valve
Hartzell BA 7497

Prop Restrictions/Placards

Folks,

Its become obvious to me that I need to summarize our approvals and placards in some tabular, easy-to-read format that could supplement what Vans provides or help others make a purchasing decision. I can't remember all the details myself... I usually have to refer to our documentation when people call or e-mail. I'll try to put together something soon. I'll be out most of next week so if you call or e-mail don't expect a reply until after Labor Day. I'll post a placard summary ASAP.

By the way, I don't do the vibration testing and approvals, that is left to John Hartmann and Lee Riedel, our vibration DERs that do nothing but that. Our department separates the design task from the vibration test/approval task to provide a natural check and balance.

Les Doud

I assume "damped undamped" is the same as the age old wording counterweighted uncounterweighted?

(cw IO-360 180hp parallel valve, 200 hp induction with WWRV200 prop and wishing I had more weight up front.)

lesdoud said:

Folks,

Its become obvious to me that I need to summarize our approvals and placards in some tabular, easy-to-read format that could supplement what Vans provides or help others make a purchasing decision. ...snip...

Les Doud

Click to expand...

That would be spectacular. I'm mulling over engine/prop choices right now.

A 7497 with an IO-390 would seem to be a good combo to test for the RV-7 guys, but how about the ECI IOX-340 and a 7496 for the RV-8 guys? I would think these are the two up-and-coming engine configurations for the next few years of your RV customers.

Either way, I'm planning on going with a Harzell, lets face it, they are the fastest CS props out there right now, and at least they are tested to some extent with engines similer to the configuration that i'll be using. Obviously, most of these other props are tested less, so they are no safer than hartzell's for a lot more money...

Les,
According to Vans order chart I can use either a 72 inch dia or 74 inch dia BA on my RV7 with an O-360, what is the difference (besides 2 inches ?
John Adams

According to Vans order chart I can use either a 72 inch dia or 74 inch dia BA on my RV7 with an O-360, what is the difference (besides 2 inches ?

Click to expand...

John Adams;

Van's says:

PROP C2YR-1BF/F7496 (I)O-360 (180hp) diameter: 74"
Application: RV-6A, RV-7A, RV-8/8A

Click to expand...

If you are building a RV-7 and not a 7A, a careful reading of the catalog will clarify that the 74 inch prop is not recommended by Van's for the taildragger. Note that the RV-7A is listed, not the 7. I have talked with Van's, in the past, to confirm that this is not a mistake.

Jim

Ok, Thanks for pointing that out, I missed it. I have a 7. Interesting, I would have guessed the added ground cleanance of a TD would suggest the longer prop. Maybe with the tail up and level the TD is less ground clearance.
John Adams

John Adams;

Originally I too wondered why the difference. In my short dialog with Van's, I learned that what we both suspected is true. Ground clearance is the issue. I see on Dan Checkoway's site, Doug Preston's RV-7 N731RV, is listed as having a 74". I pointed out the FAA guidance on prop selection to Van's. My best understanding of their response is that their experience is different. I continue to be interested in the 74" propeller for my project.

Jim