In Flight Adjustable IVO

[Norm]

I installed my Electric motor on my IVO today and did some quick flight testing.

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This is the first results with the In Flight adjustable. Previous cruise was about 90-95 mph Now115. My airspeed indicator does read about 5 high at 95 so this might only be 105 or 110 but still a 100mph KitFox. I think I am going to like this mod.

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[DesertFox4]

Should make a nice difference Norm. Looks like a two blade medium Ivo from the close up.

[Norm]

The setup is the ultralight prop but I am running two blades because I have heard so many bad stories about motor failure on Ultra light prop. I am thinking the two blade will be easier for the motor to change pitch. The picture of the 115mph is full throttle and pitched to 5200 rpm. Is this an acceptable way to run an old 80HP 912. or do I have to back off the throttle a bit. Is the critical factors the temps? Any guidance from all is welcome.

[av8rps]

Hi Norm,

I've been running an IVO ultralight 3 blade IFA on my 912 UL Kitfox 4-1200 for years now and love everything about it except for having to replace leading edge tape a couple times a season. But I'm on amphib floats, so I use the full pitch range of the prop many times every flight, which flexes the blades more than what a guy flying on wheels will probably do.

For takeoff I flatten pitch to get 5800 rpm, which helps me get on the step quicker. As soon as I break the water and climbing I add some pitch to bring rpm down to 5500 rpm, which is max continuous power for the 912. Once to altitude I put in full pitch typically and adjust power to whatever speed I want to fly at. My Model 4 on amphib floats with that monster 80 hp 912 :D at 5800 will go 124 mph wide open or 119 mph at 5500 with that Ivo. I'm not sure one could do better than that with an 80 hp floatplane (it's actually faster than my buddies $300,000 180 hp Husky amphib, which blows his mind).

To get the highest top speed you'll need to run it to 5800 rpm. But you should only do that for 5 minutes or less (which is plenty of time to show off... like when passing your buddies in their Rans floatplanes like they are standing still :cool: ), then you should increase your pitch or bring power back to bring rpm down to 5500. That is a great rpm if you are trying to get somewhere fast. I'm typically not in a hurry so I will run the engine and prop settings where it is running smooth and efficient. Many times I will fly around at 4600-4800 rpm with full pitch flying at 90 to 95 mph with a very low throttle setting burning less than 3 gph. That is also a a setting that makes the airplane really quiet for those on the ground watching you fly by (which is really nice for my neighbors on the lake).

Oh, and fwiw I have 3 sets of IVO 3 blades I play around with: 72 inch for best STOL and off the water takeoff performance, 68 inch for best all around performance, and a 66 inch that is a great cruising prop if I dont mind losing a bit of STOL and climb (hey, it's a Kitfox so it's still better than most). All of my blades are the UL low pitch version. Note that IVO makes the UL blade in a low and higher pitch. I tried the higher pitch IVO UL blade initially and found I couldn't get my 912 to 5800 for takeoff, so swiched over to the lower pitched version. If you have a 100 hp 912 and didn't want to buy the more expensive IVO Medium you would probably want to use the higher pitched version of the UL blade.

I have been running the same electric motor on my IVO for years without an issue (although I've likely jinxed myself now?). The early IVO UL IFA motors were junk and failed often. I use the later motor (which looks just like yours in the picture). Also, it is important to follow their prop set up directions closely. I use the washers as they tell you to in order to limit pitch range for your engine and prop setting. I also have mine set up so that when the electric motor starts to be loaded heavy the circuit breaker will blow right away. That's the reason they want you to use their wiring without cutting it down, and to use their specific circuit breaker -they have it all figured out for what that little motor can and can't handle (resistance).

Hopefully my rambling on here will help you to better understand and operate your IVO IFA. It truly is the greatest accessory for a Kitfox.... next to amphib floats that is ;)

[kmach]

You can expect higher rate of climb and higher cruise.

I set it for cruise like this, full throttle, set pitch coarse to get 5500-5600, reduce throttle to 5250. This reduces the manifold pressure around 1.5 to 2 inhg.

[Norm]

Hi Norm,

I've been running an IVO ultralight 3 blade IFA on my 912 UL Kitfox 4-1200 for years now and love everything about.

My Model 4 on amphib floats with that monster 80 hp 912 :D at 5800 will go 124 mph wide open or 119 mph at 5500 with that Ivo.


Hopefully my rambling on here will help you to better understand and operate your IVO IFA. It truly is the greatest accessory for a Kitfox.... next to amphib floats that is ;)

Incredible. I have been running this over in my head and wondering what makes your Fox so impressive.
I know you have referred to these numbers before and I think you must have a monster 912UL .
Someone once said it is amazing how differently all our planes run. I have been in flight with Don in his Vixen and he pitches up his prop and 118mph is his easy cruise on 80HP. I have been in DF4's KitFox IV and his 100HP does give him an easy 120-125mph cruise. Another KitFoxer with a Model 5 and the 912ULS is only getting about 105MPH. My test is very preliminary but 100mph plus makes me happy. I have a couple more things I am changing that may help improve performance, so more testing will follow. Weather has been crap here with more snow/rain mix and cool temps, and fog. Hopefully the weather will smarten up and I can get some more tuning and testing done.
I do have a set of the early Avid floats so maybe I can install those and get a performance increase.
The floats are a project for the future. They are not amphibs but I am looking at ways to change that.
I am dreaming of a trip to the lake of the woods area. If I am close I may have to stop and look at your setup. Thanks for taking the time to share your experiences.
Kevin If the trip happens this summer I would still like to stop by your place.
Norm

[Russell320]

Norm,

One more thing you may want to look at is putting the brushes behind the gear box. Merle Williams offers this mod. I've had it in my UL for years with no problems. The wires to the prop motor goes through the prop shaft.....gets them away from the front and looks a lot cleaner.

Just a thought....

Russ

[Norm]

Norm,

One more thing you may want to look at is putting the brushes behind the gear box. Merle Williams offers this mod. I've had it in my UL for years with no problems. The wires to the prop motor goes through the prop shaft.....gets them away from the front and looks a lot cleaner.

Just a thought....

Russ

I agree. I have seen the mod and it is nice.

[Norm]

Norm,

One more thing you may want to look at is putting the brushes behind the gear box. Merle Williams offers this mod. I've had it in my UL for years with no problems. The wires to the prop motor goes through the prop shaft.....gets them away from the front and looks a lot cleaner.

Just a thought....

Russ

By the Way Russ
I would be interested in your performance. Speed, RPM and if you are full throttle or off a half inch or one inch. Manifold pressure if you have a gauge and so on.
Thanks
Norm

[av8rps]

Incredible. I have been running this over in my head and wondering what makes your Fox so impressive.
I know you have referred to these numbers before and I think you must have a monster 912UL .
Someone once said it is amazing how differently all our planes run. I have been in flight with Don in his Vixen and he pitches up his prop and 118mph is his easy cruise on 80HP. I have been in DF4's KitFox IV and his 100HP does give him an easy 120-125mph cruise. Another KitFoxer with a Model 5 and the 912ULS is only getting about 105MPH. (Snip, snip)
Norm

I'm not so sure my plane is all that special, as there are a lot more things I could do to clean it up yet. And I'm confident if I removed those two 14 ft long 230 lb amphib floats it would most certainly do better. And bear in mind, many that talk about how slow or fast their Kitfox cruises are not always talking about at what specific rpm they are cruising at. I once had a friend with a very similar Kitfox to mine but no floats, and he just marveled how his would only go 100 mph, when mine went so much faster. That made no sense to me, so I questioned him further to learn his plane "cruised" at 100 mph, but that was with a prop pitched for climb and only running the 912ul at 4900 rpm :confused: I finally asked him "Ok, so if you firewalled your throttle and kept the aircraft straight and level for a few minutes, how fast would it go then?" He answered "Why would I wanna do that?" At that point I gave up. Turns out later his plane sold to someone else that was a bit more performance minded, and once the prop was pitched correctly it went 120+ mph wide open flat and level, which I would call pretty normal.

Regarding my particular Kitfox, I do think my Kitfox having minimal dihedral helps its speed some. It also appears to have little wing washout built in, which I also think helps more than most would think (I didn't build it, but the builder told me he built it to do acro and wasn't concerned about STOL at all). Aside from a few tail fairings it is pretty much a stock Model 4 with a stock 80 hp 912ul. So I really don't think there are any other secrets to it.

But you know, my Highlander is also faster than others. It will go 108 mph with 22 inch diameter tires and an open tube gear at 5450 rpm (3-5 mph faster with covered gear). Of course, that's what the factory claims it should do, so I'm not surprised. But it is lighter than a lot of later models, and lets face it, lighter airplanes are always faster...the wing doesn't need to fly at the higher angle of attack the heavier planes need. That by itself is a lot of drag.

I also own a older 180 hp Lake amphib that is faster than many of the later 200 hp models. Yet 180 lakes get berated constantly for being slow. So how can that be? When I restored that old Lake I made every effort to reduce weight. And it worked. It is actually now lighter than the original factory specs. That makes it about 150 lbs lighter than many 200 lakes.

Or maybe I'm just lucky? But I typically never win anything, so it must be the other things mentioned ;)