I recently had an E-Prop installed on my CTSW as a replacement for the three-bladed Neuform (model number CR3-65-47-101.6) that had been on the airplane since it was manufactured in 2006. I had heard about the E-Prop through Rex and Jeremiah Johnson who perform the maintenance on my aircraft (and who had been installing these props on CTSW’s and LS’s belonging to multiple owners) and from CT owners on different social media sites. The reviews from everyone were overwhelmingly positive, with most CT owners saying they had seen a 5-knot increase in cruise speeds over the Neuform. Additionally, when I looked up the specifications on the E-prop at the manufacturer’s website (http://www.e-props.fr) and you can look up what propeller can work for you by aircraft type, I discovered it had a 4000-hour TBO! Jeremiah said he could get me into it for around $2400 and get one pretty quickly, minimizing downtime; I decided to go for it.
Here’s a picture of the E-prop installed on my aircraft. It is a ground-adjustable propeller composed of three black carbon blades protected by titanium on the leading edge, making it extremely robust from impact damage over the outer part of the blade.
Compared to the profile of the Neuform CR3, the E-Prop DUR -3 is very narrow and has a sharper rear edge. (I heard that some owners were wearing gloves to protect their hands when they pull the prop through on pre-flight, so I did put a pair of flight gloves I can use for that in the aircraft, though there are ways to handle the prop that make it unnecessary.) My impression of the E-Prop when I first saw it mounted was that it was longer than the Neuform, but it’s the same diameter. However, it is 7.2 lbs. lighter (4.8 lbs. total weight from my weight and balance sheet though the website data shows 4.4.).
Where my Neuform was adjusted to give 4900-5000 RPM (usually closer to the latter) at Wide Open Throttle (WOT), the E-Prop is set initially 26 degrees but then adjusted to a value between 5000-5800 RPM on the ground to get 5500 RPM in flight. For the 912ULS in my airplane, 5500 RPM is at maximum continuous power, so getting it there gives you the most continuous power you can use.
Jeremiah Johnson (owner and prime wrench-turner of Johnson Aero, LLC at KRVS in Tulsa, OK) installed the propeller and I asked him to perform the check flights so I would not lose time doing them and could simply pick up the airplane and return home. He reported that WOT corresponded to 5600 RPM and 126 KIAS at 2500 ft MSL. He had climbed the airplane up at 60 knots with 15 degrees of flap (i.e., the nominal flap and airspeed for initial takeoff in the SW) and climbed at over 1000 fpm rate of climb (ROC). (Temperature that day would have been between 70 and 72 degrees F at the surface and the airplane would have had about 20 gals of fuel in it making its gross weight around 890 lbs.) He stated that he could dial the prop back to 5500 WOT and thought that might give me a few more knots of cruise if I wanted it.
Here’s the picture he sent of the panel during that run:
When he and I discussed whether to tweak the prop pitch anymore, he asked me if I wanted rate of climb or cruise speed. Frankly, I have never considered the SW a weak climber; on a cool day, half-fuel or so, and single pilot, I would often see 1000+ fpm minute climbs with the Neuform (15 degrees of flap at 60 knots). But that would generally be during conditions at least 10 and probably closer to 20 degrees cooler on the ground. So, this DID appear to me to be significantly better performance and in both climb and cruise. My decision was to tweak the prop back just a little to get it to 5500 WOT at cruise so I could essentially use WOT if needed without having to manage it too much if at all. As it turned out, after he tweaked it, the ground run came in at 5560 RPM with the blade angle set 1 degree higher at 27 degrees. I didn’t check it at WOT coming home because weather was an issue getting to my first stop and that had almost my full attention, though I was still noting power settings, indicated airspeeds, and ground speeds to get a feel for whether my performance expectations were being met. I’ll show you some data in a minute to show that not only were they met but they were exceeded.
On my initial climbout from KRVS, I was seeing about 1100 fpm rate of climb with the flaps at 15 and I believe I remember seeing about 1000 fpm at flaps zero and at best rate. (I had about 34 gallons of fuel in the aircraft at takeoff and I’m running about 195 lbs (a bit heavy for me) so the airplane’s gross weight would have been approximately 1128 lbs.). Takeoff temp was about 81 degrees F. so 10 degrees higher than when Jeremiah had flown his run the day before. I made several climbs that eventually resulted in cruising most of the flight at 7500 ft MSL where it was not only smooth and cool but there was a nice tailwind (I think about 12 knots). I remember seeing 131-136 kts groundspeed while running 5300 – 5400 RPM and between 117-120 KIAS. Below is a Flight Aware plot of the flight, though it didn’t pick me up until I had already passed Okmulgee. From there. I was I headed toward KF00 to avoid an area of IFR weather to the east, though I eventually realized (using ADS-B METARS and out-the window observation) that it had broken up to the point of being VFR with scattered cloud decks.
After landing, taking a break, and refueling at Mt Pleasant, Texas (KOSA), I took off into the second and last leg of the flight. Winds, cruising conditions, and down-leg weather made climbing back up to 7500 MSL my preferred option, after a short level off at both 3500 and 5500 to get oil temps back into the “green” (from the “yellow”) for each climb. It was a bit warmer, and I could tell the tailwinds were slowly decreasing. Still, I was seeing the same type of climb performance, with initial climb rates at or exceeding 1000 fpm and not getting lower than 800 fpm as the rate settled out.
As I progressed south and got closer to the Houston area, the cloud tops were starting to push up and slightly beyond 7500, and I decided to descend below the cloud bases rather than go higher. I preferred to stick with a lower route that would allow a direct approach to KLVJ from along the bay even though the ride would be hotter and bumpier. My tailwinds were also dying out; I even seemed to be taking some on the head, so I was using throttle to keep my IAS needle in the green, especially since I was bouncing around. That said, I was running around 5300 RPM and seeing the IAS at the top or within a few knots of the green arc and keeping GS around 120 KTS.
In addition to the data above, here are some more of my first impressions of the E-Prop versus the Neuform:
- The noise from the E-Prop is a bit raspier than the Neuform and I believe it to be a bit louder with a little more vibration. Not significantly so but enough to notice.
- I think it’s got a bit more torque during cruise, which means a bit more right rudder. I didn’t notice it as much during takeoff, but the rudder trim was not where I usually flew it. It makes sense that with the higher power levels this prop is running at, more torque and rudder should be expected. Again, it’s not a lot more but it is noticeable.
- The SW is a slick little airplane in a descent (especially with the flaps at minus 6) anyway but, in powered descents with the E-Prop, the airplane will accelerate much faster than you’re expecting it to and can easily get well into the yellow arc than it would with the Neuform.
- Both my landings were a more firm than usual, and I’m not sure if it was due to me being a bit “behind” on landing in the hotter days that are returning, if there is a difference in how I finesse power during landing (which I would expect to be the case), or both. Will let you know as soon as I can spend more time in the pattern with it.
- I mentioned that the rear edge is fairly sharp and you have to be careful when you pull the prop through. The manufacturer supplies soft, spongy material covers that slip over each blade and protect for personnel injury on the ground. In this shot below, the covers are installed on the CTSW post-flight.
Am I happy with this purchase? You bet! The performance gains I’ve been hearing about truly are there, and if it lives up to its expected long lifetime, it’ll be worth every penny I paid and then some. But time will tell. I’ll be sharing my experiences with the Ct and this prop on my blog and also on my You Tube channel, so stay tuned.