Whirlwind vs Aerotek propellers?

[Chele]

Originally Posted by breister

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?

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.

[breister]

Originally Posted by Chele

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]

Originally Posted by breister

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?

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.

[dsb]

"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

[breister]

Originally Posted by gmcjetpilot

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

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]

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.