Warp drive vs IVO?

[Nathaniel]

Read both the web sites, almost seems like an even race. So for those of your flying, what do you think? Acquisition cost, replacement cost, maintainence issues, medium blades I assume?. My application would be KF SS, 100hp Rotax, ground adjustable. Thanks in advance!

[DesertFox4]

I choose the Ivo prop.
The Medium for the 100 hp Rotax will serve you well. The ground adjustable is hands down the easiest prop to adjust. All of 30 seconds to adjust, then go fly to see the results unless you have to remove a spinner first but that applies to any prop.
No protractors needed to set the prop pitch. Maintenance is simple , if you get a chip in it it's an easy fix at the hangar or in the field. Now don't laugh. Crazy glue and baking soda in the chip and a small file and in about 5 minutes your off again. Keep proper torque and nothing but hours of trouble free flying. I highly recommend this prop.
Very smooth to fly behind and you will love the aerodynamic braking of the Medium should you want to come out of the sky at 2000' + per minute without overspeeding your Kitfox . On a recent test flight of a new Kitfox I saw 3000' negative on the VSI and was only at 110 mph indicated. With my "Light" Ivo I would have been over 140 mph (VNE). No way I can come out of the sky with the Light Ivo like the Medium Ivo flyers can.

My second choice would be the Warp Drive.


If you're going to be flying your Kitfox on floats you might need to consider the Warp as it does have a more substantial leading edge protection from water spray errosion but our experienced float flyers can jump in on that subject. Maybe the Ivo works well in that enviornment also but I have limited first hand experience with floats, darn it.

FYI - I have roughly 1300 hours behind Ivo props and most of the local Desert Fox Squadron members have gone to them but we are always on the look out for something new and exciting performance wise.

I'd would be interested in how the new S-LSA Kitfox 3-blade Whirlwind prop performs. It's sure a sweet looking prop.

[Slyfox]

I love my medium on the 912uls. Now if you are doing the ground adjust because of regs, sport pilot. Concider this, put the medium on with inflight adjust, but, put the controls under the cowl with the engine. Can only be adjusted on the ground, thus a ground adjustable, but now you can change things with a touch of a button, on the ground.

[Nathaniel]

Excellent writeup, thanks! Straight ground adjustable is the plan. The idea of the control under the cowl though, good one.

[Slyfox]

I know it cost for the electric option. But if you do a bunch of back country flying and you need that extra take off boost, a quick touch of a button at let say your oil door, sure would be convenient.

[Mark]

We used exactly this method on a 'demonstration' aircraft. We mounted the switch to a bracket on the engine mount where it was accessible at the oil door. You can hit the switch, then peak around the corner to check your MP. It was quick to adjust and worked great.

[Nathaniel]

This thread has brought up an interesting question for me. I like the ground adjustable because it's one less system to install, and the Kitfox has such a narrow speed range and already great performance that I feel an inflight adjustable prop isn't neccessary.

That being said, is the added takeoff performance that much different? The aircraft can already get off the ground in what? Less than 500 feet, and cruise 110+mph. How much does the electric prop improve these numbers?

I'm curious. It still may not be applicable to my mission and build but you've got me second guessing my plans. Nothig wrong with that though, it's why I'm here.

[Slyfox]

If you have the model 4 with the 912uls and medium prop. The ability to change the prop inflight. Well, lets put it this way. It's absolutely incredible.

[Nathaniel]

Anyone have any ideas about the SS then?

[DesertFox4]

Same thing with the Super Sport Nathaniel. The Super Sport if built light, 750 to 800 lbs will be wickedly exciting with a 912S and a Medium Ivo. This can be acheived easier than most would think if you start out your build thinking "lite".

The in-flight controllable Ivo will give you max take-off performance by allowing the Rotax to reach 5800 rpms or 100 hp. Anything less than 5800 is not max take-off performance regardless of the Model 4 or 7 Super Sport. Now 5800 is not necessary in most cases with a Kitfox but it can be nice to have the option when/if you really need it. Obviously the sport pilot rules will not allow you to have this feature available in the cockpit.
If you set a ground adjustable prop to max take-off performance (5800rpms) you probably will not reach 110 mph at cruise. You have to set the prop somewhere less than optimal for take-off to reach 110 mph or better at cruise so obviously the ground adjustable is a compromise at some portion of your flight. Actually it is a compromise at both take-off and cruise.
What usually happens is the ground adjustable prop will be set at 5200-5400 static rpm on the ground run-up and that will give you a decent cruise speed without over speeding the engine. The Kitfox being so agile at the low end of the speed range will be in the air long before most other aircraft even with this less than optimal take-off setting. Oh the joys of a Kitfox.
Bottom line is the ground adjustable Ivo prop while being super easy to change pitches and extremely durable and smooth will never give you max performance at either take-off or cruise.
If sport pilot requirements don't apply then by all means get the in-flight Medium Ivo. You will be amazed at the performance both at take-off and at cruise. The speed difference is worth every penny.