For Reno and the HSF STOL Drags I decided to try a NR 81" scimitar propeller to increase my climb and take off performance. After testing the thrust from the Whirl Wind to the NR by doing a pull test, the NR out pulled the Whirl Wind by 104 lbs of thrust. This made a drastic change on acceleration, but it hurt the cruise speed by about 8-10 mph. For the purpose of STOL Drags, it was a good improvement. Below is a video that summarizes my experience at HSF 2019.
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For the past year I have been working with Beringer Aero to develop a Beringer system for the Kitfox. After many hurdles the parts finally arrived and I started by installing the Beringer wheels and brakes then tested them. Then I installed the master cylinders from Beringer and tested them again. This is what airplane brakes should be. Outstanding stopping performance and over 4 lbs lighter than the Grove or Cleveland systems. If you are interested in Beringer Wheels and Brakes for your Kitfox contact Bowen Aero LLC at [email protected]. Also linked below is the Video of the 2019 Reno Air Races where these brakes proved their worth.
After much consideration I have decided to upgrade my landing gear from the Grove spring gear to a custom TK1 Racing Shock Monster landing gear. It all started with a trip to see Tony at TK1 racing for measurements and then the wait for the parts to come for install. I have linked the videos documenting this process below.
I recently moved from Oregon to Northern California where the average flying temperatures are higher than they were in Oregon. I also replaced a cylinder on the engine and now the engine is producing more power and more heat. These to factors combined have lead to me seeing higher CHT temperatures than I am used to. It is not uncommon to see the #3 (replaced) cylinder sit above 400 degrees in cruise and go higher in climbs. So I have set out to improve the air flow through the engine cowling to reduce these temperatures. Here is how this was accomplished. After many years of contemplating, I decided to go ahead and give a VG kit a try on the KITFOX. I have heard from many owners that they are not effective on the KITFOX wing. I refuse to believe that the KITFOX wing somehow defines aerodynamics. After searching the internet and talking with owners of KITFOX and CUB style aircraft, I decided to position the VG's at 4% of the Chord instead of the recommended 8%-12%. Below is a detailed youtube video of the project. Another improvement that I have wanted to do for a long time is a ground adjustable propeller. I had considered a fixed pitch Catto or Prince but really wanted the ability to adjust the pitch. Whirl Wind made itself the clear winner for my application. I have to say ordering a new prop and spinner is much more difficult than I expected. This was mostly do to relying on other people for there recommendation on sizes. Let me explain my troubles. First off I had a very hard time deciding wether to go with a 72" or 76". For STOL I have always heard longer is better, but Whirl Wind recommended the 72" for the O290D, but they don't make their STOL prop in the 72" only 76" and up. They assured me that the High speed prop would work great on this engine and airframe. A friend has a Supercub with a O290D and he has the 76" and loves it. After deciding on the 72" I was happy to discover that my friend has the O290D2 which has 10hp more and could handle swinging the O320 sized prop.
So I placed my order for a GA200L 72" and a Carbon Fiber Spinner. On my current set up I have a Saber 2 1/4" spacer that would need to have the drive lugs changed to work with the Whirl Wind Hub. I sent the Hub to Saber and they had it back within the week. The prop showed up nicely packaged and I was in business, so I thought. When I ordered the propeller they asked if I wanted the 3/8 hub, I asked if that was the correct size for the O290, they agreed it was, so I ordered the 3/8. Always measure. Turns out that I have a 7/16 lugs on my prop flange. Well shoot. So the Hub had to go back to San Diego and this would cost me shipping both ways and a week and a half. Whirl Wind was very understanding and helpful to make it possible to get the correct Hub. Great customer service. Finally after it being delivered to the wrong address, USPS's fault, I was ready to install it on the airplane. It didn't take long to be disappointed yet again when I discovered that the style of spinner would not clear my cowling. This is why the pictures below don't show my new beautiful spinner. My previous spinner mounted to the front of the propeller and the new one mounts to the rear of the Hub, so long story short, the spacer needs to be replaced with a 3" Saber spacer. Sam at Saber is absolutely awesome to work with and he offered to re-use the drive lugs I just had installed on the old spacer and reduced the price of the new spacer. I plan on doing more testing before pulling the spacer to send to Texas. Edit (update) Turns out that the spinner set up would work on the original spacer if I turned the back plate around and faced it the other, proper direction. This is different than my previous set up and thus the confusion. This mistake cost me several weeks and a $400 saber spacer that I now have no use for. So here are the numbers. Side note, make sure you level the airplane to flight level position before starting. 17 degree pitch matched the static RPM of my wood prop from Props INC. 2350RPM. I gained 6mph in a comparison test at 2300RPM in flight, but just like the wood prop I was only getting 2500RPM max in level flight. So I decided to back the pitch to 16 degrees. At 16 degrees it was still 2-3mph faster than the wooden prop, Static RPM 2550 and in flight 2650RPM. Three things that were notable, first the take off RPM was 2400RPM which was the goal of this entire project, and second I saw a .8 gallons per hour decrease in fuel flow at a cruise setting of 2100RPM, which reduced it to 4.4 gallons per hour. I look forward to comparing numbers at other settings. The third thing is that it is so smooth at all RPM's. This is the best improvement. The wood prop had RPM ranges that just didn't run smooth. The Whirl Wind is smooth from idle to 2600RPM. Was it worth it? It was the most expensive upgrade that I have made to date and I'm not convinced yet that it was worth the price tag, but once that carbon spinner is on there I think it's going to look fantastic and I am already seeing flight improvements. I made the trip to the 2017 High Sierra Fly-In this year and competed in the STOL Drag races. This was an absolute blast and I even made it to the top 8. However, I learn that there was room for improvement, both with the aircraft and the pilot. One of the upgrades that I decided to make was the T3 Tailspring from Airframes Alaska. This spring assembly has a shock in it that makes for a very smooth ride when off airport and it prevents the tail from bouncing when really planting it for a short landing. I noticed that the bounce was an issue during the races. This was an easy install, the only hurdle was that one of the provided bolts was too long, but the local FBO (Benton Air Service) hooked me up. The off airport performance is a noticeable improvement. I have to thank Scott Noble for the advice on making this upgrade and agree that it is well worth it.
Added a Flight Data Systems FC-10 Fuel computer today with the FT-90 gold cub sending unit. I basically re-plumbed the fuel system from the header tank forward and also changed out the old 3 position fuel shut off valve with a 2 position valve from Kitfox. I can not express how nice it is to have this fuel flow information. In an experimental I think it is a mandatory instrument. It helps determine power settings for different desired cruise and climb, and also helps keep track of how much fuel is onboard. Installation was not a problem, well worth the time and money.
After all the upgrades and testing it was time to take the Super Fox to the Idaho backcountry. This was an epic trip with some good friends and saw some amazing country. Here are some highlights, also check out the video in the video section.
Thats it, I can not stand one more flight with this POS VAL radio. Upgraded to a great Garmin GTR 200 radio with standby frequency monitoring, effectively making it 2 radios. Clear transmission and nice digital display. Its amazing that all my flying friends can actually understand what I'm saying on the radio now. this unit has a built in ICS system so I was able to remove the other one. That combined with the weight of the old radio saved me 1.9lbs.
Installed a G3 Insight graphic engine monitor today. It is set up to monitor all 4 cylinders EGT & CHT. Another nice improvement.
My model 5 came with the option to make wingtip extensions to extend the shortwing out to the standard wing length. Do to the type of flying I do I felt that the full wing is a better fit, however this means I have to make the extensions. Again a worthwhile project. This improved cruise speed, shortened T/O distance and landing distance, I did loose the roll rate that makes the shortwing fun, but a good trade off.
With the proper main wheels I needed to improve the tailwheel situation. Matco WHLT-8WD TAILWHEEL, DUAL FORK 8" PNEU. Huge improvement to have a pneumatic tire back there to soften up the bumps.
This was my first real airplane camping trip since I got the Kitfox. I posted a video in the video section. Alvord is a great place to take an airplane. Its a giant playground.
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