Kitfox Series 7 Super Sport - Show Me Fox

[alexM]

I have been looking at the Sensenich 3 Blade Ground Adjustable Props. I was wondering if anyone had any experience with them?

After speaking with the rep today I understand they are furnished with 6 indexing pins. To set the prop pitch you simply turn the blade to full fine insert the index in of your choice then turn the prop blade to engage the index pin.

Basically there are 6 positions you can set the prop and the index pins provide a quick and repeatable way to adjust the prop without protractors. Each pin will adjust the pitch by approximately 1 degree or 3” of pitch.

I may be posting a used Whirlwind Prop and Spinner for sale in the near future if all this checks out. I will be visiting their booth at AirVenture in the coming weeks.

I have the Sensenich two blade on my plane right now. Can't say as I've flown behind it but I have installed it and set the pitch using the pins you mention. It's a very cool concept. Not quite as fancy as the Duc prop with the single Allen Wrench hole in the middle but still pretty awesome. Quality of the prop is outstanding. The blades are beautifully made. I checked tracking on mine just last week and the blades track less than 1/16" apart.

If you search the web you'll read where people caution you to still use a protractor to check the blade pitch when you set it with the pins.

RE: Rivnuts
I've a very vocal Rivnut hater based on my career with the big airplane company. All it takes is one spun rivnut to ruin your entire afternoon. There are locations where you don't have a choice. When that occurs: ALWAYS use "keyed" Rivnuts, DO use something to help secure them like the Loctite that Gary uses, DO run a screw through them several times to make sure the threads are clear before you put parts together, DO NOT ever let some knuckle dragger anywhere near them once installed.

[Jason Murphy]

I have the Sensenich two blade on my plane right now. Can't say as I've flown behind it but I have installed it and set the pitch using the pins you mention. It's a very cool concept. Not quite as fancy as the Duc prop with the single Allen Wrench hole in the middle but still pretty awesome. Quality of the prop is outstanding. The blades are beautifully made. I checked tracking on mine just last week and the blades track less than 1/16" apart.

If you search the web you'll read where people caution you to still use a protractor to check the blade pitch when you set it with the pins.

RE: Rivnuts
I've a very vocal Rivnut hater based on my career with the big airplane company. All it takes is one spun rivnut to ruin your entire afternoon. There are locations where you don't have a choice. When that occurs: ALWAYS use "keyed" Rivnuts, DO use something to help secure them like the Loctite that Gary uses, DO run a screw through them several times to make sure the threads are clear before you put parts together, DO NOT ever let some knuckle dragger anywhere near them once installed.

Thanks Alex,

After speaking with the Sensenich President Steve at AirVenture he advised me of a new prop they released specifically optimized for the Rotax 912 iS and the Vans RV12.


It is the 3YO it’s been out for a few years. It is not on their website. I spoke with Phil from Lockwood aviation and he said that is the prop they are using on their AirCam and he is very pleased with it. I emailed photos of the 3YO to Steve and he reported the 3YO and the Whirlwind Spinnner I have are compatible.

The trade I will make for this setup is the 3YO does not have an adjustment pin. It is similar to yhe Whirlwind where the blades are simply clamped in the prop hub and lined up with a protractor.

Another piece of advice I received from Phil was I should set the pitch to achieve a certain RPM and power setting and stop messing with it. There’s probably a lot of truth to that advice.

[Kitfox Pilot]

RE: Rivnuts
I've a very vocal Rivnut hater based on my career with the big airplane company. All it takes is one spun rivnut to ruin your entire afternoon. There are locations where you don't have a choice. When that occurs: ALWAYS use "keyed" Rivnuts, DO use something to help secure them like the Loctite that Gary uses, DO run a screw through them several times to make sure the threads are clear before you put parts together, DO NOT ever let some knuckle dragger anywhere near them once installed.[/QUOTE]


Haha, finally someone who agrees with me about rivnuts!

[alexM]

Wow, look at all that cheap labor! Great that your family members help out.

I'm a big fan of water based stuff (like Stewart Systems)where ever possible. The people who don't like it are generally people who ignored the instructions and applied techniques from legacy systems and got crabby at the results. Stewart Systems used to be in Washington (not too far from Geek), and attended Arlington every year. The planes they brought to show in their booth were beautifully covered.

If I were to build another Kitfox I would put the magnetometer in the right wing too. My left rear spar is a bit busy with pitot/AoA tubing, CANBUS and power for the magnetometer and wires for the WAT tip lights. It all fits but spreading the love would be better.

[Jason Murphy]

Sanded the forward edge of the vertical stabilizer. I was concerned about how the weld bead would show through the fabric. I believe it blended in well with the Superfil body filler.

I also finished bonding the No 2 rib and sanded the transitions between the lower false ribs and the leading edge of the wing. I will need to return with my 3/8” rod and work on the sides.

After all the thought and planning regarding the heated pitot I decided that I didn’t want to go that route. I reached out to Stein Air and they will exchange it with an untested pitot. Realistically the cost savings will be chewed up by shipping. I will be packing it up and sending it back after I return from Reno. This will slightly simplify the build. I was also under good advice that I probably will never fly the thing in a situation I would actually need the anti ice / de ice capability and if I do things have seriously gone wrong.

[bbs428]

You’ll be glad for the simplification of your build.
I think back to all the stuff I did or wanted to do and now that I’m flying, all the gizmos seem not that important.
If I were to build another Kitfox it would be a bare bones style VFR with a few steam gages and an I-fly.
Going with the streamlined metal wing strut would be a good upgrade as it’s handy to push and pull on when jockeying the aircraft around. The fairing’s over the tube lift-struts are fragile. Too bad it’s such an expensive upgrade!

Keep up the great work Jason!

[Jason Murphy]

Getting ready for a trip out west for the Reno Air Races. I plan to stop in at Homedale to exchange my plain firewall for a burnished firewall.

Applied a dollop of Superfil that had been thickened with micro balloons to the wing tank. Used levels to bridge the space between the No 1 and No 3 ribs. Used tongue depressors and index cards for spacers to match the contours of the adjacent ribs.

Applied extra superfil to the false ribs. Mixed another small batch and filled behind the antenna plate and the front of the vertical stabilizer.

I would be interested in hearing from other people areas they had filled or wish they had filled.

[Jason Murphy]

10 ga is overkill for the pitot heat. You will probably have difficulty terminating that large of a wire. I think 14 ga is commonly used with a 15 A fuse or breaker.

Yeah yeah yeah. They've always worked well for me as long as I don't ask them to do something they weren't designed for. Just kidding with you Harlan

Yup. The Stewart brothers who started the company still live close by. Really good guys who are willing to share their experiences.

These comments are right on Jason. I used 14ga on mine and it works perfectly as far as I can tell. I say that because the controller varies how much current actually goes to the heater based on OAT. I'd be really surprised to ever see the system ask for full current but even if it did, 14ga is good. While I don't expect to fly mine in that kind of cold where I need a lot of heat, my training was that if you flew into rain - turn on the pitot heat. Doesn't take a lot of heat to deal with the rain but still helps keep water out of the system.

Like Alex, I love how your kids are involved in the build. The time spent now are the memories you have later. Those are priceless.

Geek

Agree. 10ft of 14AWG will have ~0.025Ω of resistance. At the full 10A, you'll see 0.25V drop at the pitot tube. Insignificant.

10ft of 10AWG will have ~0.01Ω of resistance and 0.1V drop at 10A. It will weigh about 2.5 times as much as 14AWG.

I wanted to thank everyone for the incredible responses and discussion, I would like to discuss the topic a little further and gather additional thoughts from you.

For those of you who are running the 14 ga wire how are your routing the wire?

I have not actually measured the total length of the wire run but I estimate if you ran the wire down the spar tube and back to the pitot probe you would have at least 18 ft and that doesnt count running the wire through the cabin to the power source. P. 75 of the G3x install manual calls for 10 g wire for distances of 20 to 30 ft.

I purchased the unregulated pitot so unfortunately I do not have anything which would decrease the demand of the heater. Perhaps Stein would work with me on this and I could trade up.

[Eric Page]

For those of you who are running the 14 ga wire how are your routing the wire?

Some of my wires go through the spars (wingtip lights, mostly), but some others for items mounted closer to the cabin went through a small gap between the spar tube and the fuel tank. I held them in place with small dabs of latex caulk. The wires are below flush and won't print through the fabric.

...I estimate if you ran the wire down the spar tube and back to the pitot probe you would have at least 18 ft and that doesnt count running the wire through the cabin to the power source. P. 75 of the G3x install manual calls for 10 g wire for distances of 20 to 30 ft.

If it's an unregulated heater, then Garmin probably wants 10AWG for longer runs because they rely on a minimum voltage across the fixed resistance of the heater to produce the promised heat output. Less voltage = less current = less heat. In the grand scheme of things, <1lb of extra wire in one wing isn't going to make your plane fly crooked! Whatever keeps Garmin's warranty department happy...

Are you building an IFR airplane?

[Geek]

I wanted to thank everyone for the incredible responses and discussion, I would like to discuss the topic a little further and gather additional thoughts from you.

For those of you who are running the 14 ga wire how are your routing the wire?

I have not actually measured the total length of the wire run but I estimate if you ran the wire down the spar tube and back to the pitot probe you would have at least 18 ft and that doesnt count running the wire through the cabin to the power source. P. 75 of the G3x install manual calls for 10 g wire for distances of 20 to 30 ft.

I purchased the unregulated pitot so unfortunately I do not have anything which would decrease the demand of the heater. Perhaps Stein would work with me on this and I could trade up.

Hey Jason - I did not route my pitot wiring up to the spar and then down the spar due to the added length. Mine runs down to and then behind the fuel cell where it comes out very close to the rest of the wiring/pitot tubing that is running down the spar. So on mine it's not the 18 feet you were looking at. The real reason I went with 14ga is that the current draw vs temp is not 15 amps. (I also put a 15A breaker inline so the wiring is protected). Second part would be how cold is it where I am going to fly at? When it's freezing outside you will find me in front of the fireplace with a good book and a bourbon. But I did test it when the OAT here in WA was -12 degrees F this last Winter and my 15A breaker didn't pop and the probe was warming. To illustrate why I am not a big fan of the G3X install manual, the information on the actual current draw is Table 2-1 on page 2-16 (rev AT manual) and not where you were looking (but where you, me and everyone else would think it would be). Here's a mock up of the table (it didn't want to copy nicely on here)

"Table 2-1 GAP 26 Initial Current Draw vs Probe Temperature (-10, -20 units only)
Probe Temperature -40°C (-40°F) - 12A, 0°C (32°F) - 9.25A, 50°C (122°F) - 7.3A, 100°C (212°F) - 5.85A, 175°C (347°F) -4.36A
Notes (from the table in the manual)
Table 2-1 refers to probe temperature at initial turn-on. For example, upon turn-on at -40°C, the standard
(-10) or regulated (-20) heated probes will initially draw 12 amps, but will draw less current as they warm
up.
The -10 non-regulated probe draws current proportional to the probe temperature as shown in Table 2-1.
The -20 heated regulated probe uses similar power to the -10 probe when airborne, but will limit the
current to regulate the probe temperature to ~75°C (167°F) when the probe temperature reaches this
value."

So two takeaways for you from the table are that the 12A draw is start up current and not constant and the second is that you are probably OK with the -10 version probe. The -10 version does draw current proportional to the temp based on the temp. The -20 regulated version regulates the current based on actual probe temp. (If I had read this before I ordered mine I probably would have gotten the -10)

Keep up the great work Jason. Like following your build.

Gary