Changing Props

[scubarider2]

Going to change out my 3-blade 70in Warp Drive prop for a 3-blade 68in Sensenich on my Rotax 912uls. Will be ordering soon. Will post some performance stats once done.
Dennis

[Jack L]

Dennis,

Just curious, why did you decide to go with the 68" vs the 72" Sensenich propeller?

Jack

[scubarider2]

Jack. The 3-blade comes with a 68in instead of the 70in. I could get a 2-blade at 70in.
Dennis

[scubarider2]

I think I am going to go ahead with the purchase. Open up the wallet, bite the bullet, etc etc etc and just do it.
FOR SALE: 3-blade WARP DRIVE 70in with leading edges plus a 2in spacer and all hardware. If interested PM me.
Thanks!
Dennis

[av8rps]

Dennis,

I bought a used Sensenich prop just like the one you plan to order. I haven't had a chance to test it yet, but believe it will provide a higher cruise speed while providing a very similar climb rate to the longer Warp 3 blade. I base that on a few friends that fly the Sensenich 3 blade on their Vans RV12 LSA's. (they say "it is the prop to have on the RV12").

Granted, our Highlanders are at the other end of the LSA spectrum compared to the RV12. And we have a lot more available ground clearance than an RV12, so we have the option of running the longer props that generally perform better in the STOL environment. But if a guy is looking for a better overall cruise speed while still being able to do respectable STOL work, I think the 3 blade Sensenich will be a great choice. (BTW - when assembled it actually has a 69 inch diameter - I measured mine)

I've always liked the look of the Sensenich scimitar shaped blade, thinking it should be a very efficient prop. And it certainly is a beautiful prop. So when I ran into a good deal on one I jumped on it. And if nothing else, I thought it would at least be fun to experiment with. I originally thought I might replace the IVO on my 80 hp Kitfox amphib with it. But my 68 inch IVO 3 blade (IFA) on that performs so amazingly well that I hate to change it out (even though I'm not real fond of the flimsy blade and the problematic leading edge tape). So I think I might just run this one on my next Highlander. If it works as well as my 2 blade 70 inch Sensenich does on my current Highlander, I'll be more than happy with it. I know there are much better props out there for maximizing the STOL capabilities of our airplanes. But since our planes do so much better for STOL than anything else out there, I'm willing to sacrifice a little bit of that STOL in favor of some extra cruise speed that gets me to places faster, and more efficiently. I think so many times we have a tendency to get wrapped up in getting more and more STOL ability from our airplanes, and tend to forget that if we can stay more reasonably propped that our Highlanders are actually pretty good airplanes for going places as well as booney bashing.

I know long props is the current trend as it optimizes STOL performance. But flying floats actually demands more prop and engine performance than does STOL (adding a set of amphibs is like flying around with 3 people in your airplane all the time...). So I am well aware of the needs for getting the most out of your prop. But what I've learned in the last 400+ hours of flying my 80 hp Kitfox amphib is that we have the technology today in props to achieve better cruise speed while still getting reasonable STOL performance.

A good example of that is when I tested 3 different IVO prop blade lengths (all the same airfoil) to learn that an old cut down 66 inch 3 blade IVO gave me 8 mph more top speed than a 72 inch, but almost 200 fpm less climb rate. So I ultimately settled in on a 68 inch 3 blade IVO. It provided a very similar top end to the 66 inch prop, but was only 50 fpm less climb than the 72 inch. So my experimentation paid off. And even though I've shared my results with many of my Kitfox buddies, they refuse to leave their 72 inch warp props. Yet they comment about how "fast" my Kitfox is compared to everyone elses, and believe it is in the rigging, streamlining, etc.?

The only real downside I found of the 68 vs the 72 is when you are landing the 72 inch provides much more braking effect. But hey, that's what slips are for, right? And while I think the Sensenich 3 blade is a very nice propeller, I think they need to get rid of their "adjusting pin" concept, as people that have used the prop complained that the concept sounds a lot better than it works (the two blade I have also had some new novel "adjustment knob" that didn't work either). Save money on pins and buy a Harbor Freight $30 digital angle gauge and set all 3 blades with that. I can't begin to tell you how many guys have complained about poor prop performance only to learn that their blades are not set the same (the equivalent of having one wing on your plane set to a different angle of incidence than the other )

With all that said, I can appreciate what you are trying to accomplish Dennis. I think it will be interesting to see how a streamlined Highlander like yours will do with what I believe to be an ultra efficient propeller.

Paul

[carpat]

Hi guys,

I recently upgraded my Highlander from a 72 Warp Drive to a 68 Sensenich. What I noticed was a slight speed increase of about 3-5 mph for the same rpm. The biggest improvement was for sure the smoothness of this prop. With the Warp Drive my windshield was shaking badly from the turbulence created by this prop. Now I barely notice my windshield shaking with the Sensenich. All in all, I'd would have liked to get 10 mph more speed obviously but I'm more than satisfied with the result. Also, don't forget that this prop is much more nicer and most important much lighter than the Warp Drive. So it will save your engine sprag cluth on long term.

By the way, I want to share with you a big point. I also recently upgraded my Highlander dramatically from a standard landing gear with 8.50 tires to the extreme landing gear with ABW Airstreak 29'' wit Pekola tailwheel 10''. This is a completely new aircraft. Landings are so smooth even on rough fields. I just can't believe it. Also, for those who hesitate by covering their landing gears or not. Guys please do it. My standard gears were not covered and I covered my new extreme gears. I just couldn't believe what happened on my first flight. At the same rpm I'm now getting 8-10 mph more speed. That changed my flight attitude by lowering the nose a bit down resulting higher cruise speed.

I am more than pleased with my aircraft.

Fly safe,

Pat
C-FABO

[av8rps]

Hi Pat,

Nice write up on your results of moving from the Warp 72 to the 3 blade 68 Sensenich. I'm not surprised at the cruise speed gain as that is in the range of what I expected. But I'm curious if you noticed any climb rate loss by going to the 68 inch?

My Sensenich 70 inch 2 blade on my current Highlander is also a really smooth prop. I don't get any of that windshield vibration either. I know Sensenich hasn't been discussed much previously on this forum, but I really do think they make a nice prop that performs well.

I'm also curious after hearing about your speed gain on the covered gear, did you also streamline the round tubing on the gear before covering it? Or did you just cover the round tubes without additional streamlining?

Also, did you make streamlined bungee cord covers, or did you just use the factory vinyl covers that velcro on?

Paul

[scubarider2]

Thanks guys for all your comments and stats. I am moving forward with the Sensenich 3-blade. Trying to work on what spacer I need. I currently have the 2in. Saber but am wanting to cut that down some. Will go out and measure tomorrow to see what I can do. I am very eager to try it out. I have heard I need to be much more careful with the Sensenich than I am with the Warp when it comes to rocks etc. Since I am on tricycle gear and have minimal clearance from the ground the 2in less on the Sensenich will work just fine. No gravel roads etc for me any longer which means I will not be landing at the factory.
Dennis

[carpat]

Good evening Paul,

To answer your questions, with my Sensenich set up to 5650 rpm WOT at level flight just like my Warp Drive was, I lost about 50-100 fpm. So very negligible. I still climb between 1000 to 1200 fpm at 55 mph depending of the air density.

About my landing gear, I didn't streamline the back of the gear when I covered it. Before covering the gear I was cruising at 101 mph at 5300 rpm with 8.50 tires. Now with the gear covered and ABW 29'' I cruise at 109 mph at the same 5300 rpm. This is an amazing improvement considering that I gained weight from the bigger tires and landing gear. What can I ask more??? I have a faster airplane with more STOL capabilities.

Pat

[av8rps]

Dennis,

Yes, I agree you will have to be more careful with the Sensenich than the Warp. But that would be any prop compared to the Warp. The Warp is for sure one tough prop. But the Sensenich will handle some of that rough stuff as they put a pretty nice metal leading edge on it.

I'm eager too to see how it works out for you.

Paul

Thanks guys for all your comments and stats. I am moving forward with the Sensenich 3-blade. Trying to work on what spacer I need. I currently have the 2in. Saber but am wanting to cut that down some. Will go out and measure tomorrow to see what I can do. I am very eager to try it out. I have heard I need to be much more careful with the Sensenich than I am with the Warp when it comes to rocks etc. Since I am on tricycle gear and have minimal clearance from the ground the 2in less on the Sensenich will work just fine. No gravel roads etc for me any longer which means I will not be landing at the factory.
Dennis

[av8rps]

Pat,

I'm glad to hear that your results are most of what I anticipated with the Sensenich. And while you did lose a little climb, these Highlanders perform so well that you can probably still outclimb anything you fly next to.

And thanks for the info on the landing gear. I like the open tube gear for booney bashing, and even like the look overall. But I've always suspected it cost more speed loss than most would ever guess. Round tubes directly into the breeze are a lot more drag than I even thought. I think I'll be covering my gear on my new HL.

What's cool is that by cleaning up the gear, even with ABW 29's you are still getting a very nice cruise speed. That's impressive.

I agree, what more can we ask for? These are just awesome airplanes!!!

Good evening Paul,

To answer your questions, with my Sensenich set up to 5650 rpm WOT at level flight just like my Warp Drive was, I lost about 50-100 fpm. So very negligible. I still climb between 1000 to 1200 fpm at 55 mph depending of the air density.

About my landing gear, I didn't streamline the back of the gear when I covered it. Before covering the gear I was cruising at 101 mph at 5300 rpm with 8.50 tires. Now with the gear covered and ABW 29'' I cruise at 109 mph at the same 5300 rpm. This is an amazing improvement considering that I gained weight from the bigger tires and landing gear. What can I ask more??? I have a faster airplane with more STOL capabilities.

Pat

[scubarider2]

Ordered the Sensenich prop today.
Dennis

[scubarider2]

If you are interested in a Sensenich prop PM me or contact Jack. Got a great deal and loads of support so far. Will keep everyone posted once I get it on the plane.
Dennis