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wannafly
06-08-2009, 08:27 AM
Ok....all your talk about the rotax has me convinced to change out my engine...why?...because I can!
so we will see how the performance changes
I bought my Kitfox IV speedster with the EA81 subaru in it 5 years ago and it is a great running engine but everyone tells me it is to heavy and that is why my performance is so poor. I didn't know any better. Have had a great time with it so far, it climbs great and gets off the ground fast but the top cruise always bugged me because you guys keep saying that you are getting upwards of 110-120 mph cruise. My empty weight is 750 lbs and cruise is 85 mph with fuel burn at 4.5 gal/hr....warp drive ground adjustable prop. Tryed all differant settings on prop with out much change of cruise. So this will be a real life test with the same aircraft.
old engine EA81 Subaru 113 hp on the dyno, warp drive prop
new engine 912 S 100 hp, IVO medium inflight adjustable

Mr Moderator (Steve):)
I really hope you are right in your claims
expensive lesson other wise.:eek:

but someone has to take one for the team.......LOL

Slyfox
06-08-2009, 01:10 PM
You are going to love your new engine. That being said, how old is the engine? does it have the slipper clutch?

THe only advice I can give you on the new engine is... Hold on to your hat. it will scare you, particularly since you only had a cruise of 85mph. Mine will do that when I have the prop flat. I usually run at 110kts which is about 130mph. I did get my RV up to 190 today so I guess that's slow also. Have fun with your new airplane.

wannafly
08-19-2009, 10:18 PM
well guys we are finally getting ready for the first start up. Hope to do it on Sunday and if all goes well maybe a start of the test flights.....YES

wannafly
09-17-2009, 08:00 PM
have had electrical issues so it has not run yet...very frustrating...will be sure and post once it gets going...believe me it has been way to long a project in my opinion....:mad:

wannafly
09-18-2009, 06:24 AM
have had some electrical issues...still not running:mad:
will keep you informed as it happens....

Slyfox
09-18-2009, 08:29 AM
very important that you also do a weight and balance.

Slyfox
09-18-2009, 09:57 AM
I don't know if you have posted your electrical problems yet. But, I do have the 912uls that I just installed in January. I since have changed out the tach and all the sensors did not jive with my guages:(. I would concider going individual switches on the mags, I love that with mine. I currently have a key switch for the start, but like the RV am going to get a push button. If it's the charging, you should have gotten a new regulator, just wire in the new one and be done with it. If you need a good wiring diagram, there are some available on line from rotax. Good luck.

steve

wannafly
09-18-2009, 09:40 PM
yes weight aand balance is on the menu...as far as the electric is concerned the guys at rotax are working on it...I thought I would leave it to the experts. They have the Kitfox in their care and only when is it puurrring will it come home. Actually I will go to the shop and test fly it there so if there are any further issues they will have full access to figure things out. Thanks for the imput though.

wannafly
09-27-2009, 10:19 PM
we had a very succesfull engine start up today...engine oil presure was good...we ran for about 30 minutes at the longest strech and oil temp reached 120...we have nor reading on the tach so we put a new one in with the same result will do further checks tomorrow. Starts and runs smooth...new weight and balance says we lost 54 pounds doing the change over from the subaru...test flight is a comin

Slyfox
09-28-2009, 03:39 PM
Lets see here, I came out with about 630 on total weight, and the tail was somewhere in the 40 pound range. If you need real weights I can get them.

I will say with 60 pounds shed, you will be really happy with the results.

hold on to your hat:D

Slyfox
09-28-2009, 03:41 PM
Just might be something simple like, power to the guage . I believe two wires come in from the engine, than power and it should work.

OK, I just looked in the rotax heavy duty maint. manual and the tach runs with two wires. The bl/ge wire and the ws/ge wire. those go to the tach and I would think the third is power . Now your saying what are rotax's codes for the wire colors. I got those also. GEt this, the bl = blue ge=yellow and ws = white. Those wires come off the back of the engine where all those sensors are off the crank. I believe you should have had a wire harness with connector for install, just take that harness and run it right to the tach. Hope this helps.

wannafly
09-30-2009, 11:51 AM
tach is now working...did some full power run ups...everything seems in order...now wait for the wind and rain to go away and its test fly time:D

wannafly
10-02-2009, 08:06 PM
everything has been checked and double checked...the weather for sunday looks like the day...forecast is 13 degrees C or 53 F for my american friends and light winds
heres hoping for a banner day:D

DesertFox4
10-02-2009, 10:06 PM
The very best of luck Mic. Hoping everything goes as planned. Remember you are a test pilot again. Expect anything. Most of all expect a very quick take off. ;)

wannafly
10-05-2009, 08:00 PM
Well I finally have some results for you. The test flight went on sunday morning. The temp was a cool 40 degree F, field elevation is 1750. The results were absolutly totally off the chart. Your words of caution were right and I could not have been more surprised. After numerous run ups and systems checked again it was off to the taxi way. When I did my first full power run up with out it being tied to the truck I realized the incredible thrust. Oh boy is this amazing. I could only hold it for maybe 10 secounds and it started to roll forward and I could not hold it any more.(Guess the brakes will need an upgrade next) So off to the runway and with 4200 feet of run way did some taxiing. Idle is set at 2000rpm and with 2500rpm I could get the tail up and 35 mph...wow. So off to the far end gather my thoughts and wits and slowly advanced the throttle. At 3500rpm I felt it skip and thought this thing wants to fly and I just started my roll out continued on to full power and it wanted to go up so up we went. In moments I looked down to see 60mph indicated and a rate of climb at 1800 fpm (Yes really). My coaches on the ground told me what ever you do not cut power until you are at or above cicuit height. So I kept it at 5500 rpm and 16-1800 fpm till 4000 ft. The plan was to level off there. I pushed the nose down and in a heart beat I was at 110mph. Tryed to trim it out but was not used to seeing the nose that low in level flight and with out realizing it continued to climb to 5000 feet. At this point I'm thinking ..How am I going to get down? It just wants to go up. More trim and then it hit me The flaps. I did not use any on takeoff but I can push the lever past 0 and so I did and this helped big time to level off. I would say about 25% negative flap(this may be my new 0). At this point my rpm are up to 5800 so backed off the throttle to 5500 rpm. Cruise is showing 110. then two up clicks on the IVO medium rpm drops to 5200rpm and I am at 120mph. I did a few more curcuits and the head temp stayed at about 150 and oil temp at 200. Oil presure was good so I did a power off stall to see what had changed in the stall department incase it was way differant from what I was used to and I would know it ifit happened while trying to land. Nothing changed in stall, a basic slight shake and nosedip and forward stick, full power and flying again with only 2-300 feet lost. So into the curcuit I go and pull back to 4000 rpm; not coming down fast enough, 3000rpm...ok thats better dropping about 400 fpm. Turn my base leg and look for the runway. Where did it go? At 110 mph it does not take long to be 4 miles away from the runway. Amazing but will have to get used to the extra speed. At about 1 mile final I see that if action is not taken I will have to go around, so idle down to 1800 rpm and side slip to make sure I hit my mark which was the wind sock about 500 feet from the end of the run way. I thought I hit mark but when I leveled off and flaired it just kept floating. Look down and I still was at 70 mph.oh oh good thing I had 4200 feet of runway. I just waited for the speed to bleed off and greased it on(not really...when I touched I am used to dropping the tail cause the heavey engine would keep the nose down...not now...up I went a little power and let it settle again, this time kept the tail up..and it stayed down)
I flew 5 years with the subaru power and knew the flight charactoristics pretty good but am definitlly going to have to relearn them with 50+ less pounds.

So that is my first 45 minutes behind the 912S in my Kitfox IV Speedster and all I can say is UNBELIEVABLE. Will continue to refine and tweek and figure out how to land. Tomorrow I will check it all out again and head off again. The results are not final but it is definitly encouraging.

Thanks everyone for your advise and words of wisdom...words can not explain the excitement I feel ...it is way to cool :cool:to be able to enjoy the privelage of flying:D

Slyfox
10-06-2009, 08:00 AM
When I went from the 912ul to the S, I got quit the suprise as well.

On landing there are two things you can do. One, back off the idle 1/2 turn on each carb.

When you do this, you can pull the throttle back on final and slow it much better. The only thing now is as you touch down you need to add a little power so you don't get the chuggle in the engine. Takes practice but well worth it.

The next thing you can do is run with full right rudder, level wings over the numbers down the runway until you hit about 60mph. Than straighten and touch down. I do this quit a bit.

Have fun learning your new machine, she is now a winner.

Slyfox
10-06-2009, 08:17 AM
OH, here is another suggestion. When you go into the pattern. Pull back the throttle until about 4500rpm and than flatten the prop. Watch the rpms and you will know when this is when the rpms go up and stop. Now you can lower the idle and feel the plane slow. If you do what I suggested on the idle, you can really slow er down. Than if needed, you can push in on the right rudder and run it level and over the runway about 10ft off until you reach about 60mph, than straighten and land it.

You now have an aircraft that is fun.

Oh and if you want to fly around slow, do this. Pull back on the idle to around 4500rpm flatten the prop all the way. Than increase the idle to about 5200 and now you can fly all day long at about 83kts. A great speed for low and slow and playing around.

Now when you take off, be careful, if you do a normal take off with full power, you might overrev. So watch your rpms when taking off. To fix this, just hit the switch for the prop and course it out just a little and keep the rpms at 5800 until you level and than take it down to 5200.

have fun, I know you will.

wannafly
10-06-2009, 09:30 AM
here is a pic of my Kitfox. Will try and get some engine shots and post them as well

DesertFox4
10-06-2009, 11:18 PM
Mic, good report. Sounds promising so far. You now have the best weight to power ratio possible on a Kitfox short of bolting a jet engine underneath.
I've considered it. Kind of a mini Jimmy Franklin set up. Rotate, then straight up out of site. 600 lbs of thrust would be exciting. Would I need a twin engine rating?

Mic, try 1/2 flaps on take off when you feel comfortable. My normal take off now utilizes 1/2 flaps for max performance.

Do you have an electric trim tab on your elevator?

Also noticed the negative flap setting comment. Interesting as I could go to negative in cruise if I remove a temporary stop on my counsel. I've never tried it yet. Was told that in cruise it will improve speeds a little. Also was warned not to try to take off with negative flaps deployed. I heard some years back we lost a Kitfox that tried to take off with the flaps set to some unknown degrees of negative. Does anyone know of this? Just wasn't sure if I remembered that correctly. Maybe some of you have tried it and it's not a problem.

wannafly
10-07-2009, 06:29 AM
Steve

Yes I have an electric trim on the elevator but I had run out of travel which is close to 1.5 inches both ways.

As far as the negative flap I will do some degree measuring and see what it says. In flight it looked like the flaperon was parallel with the bottom of the wing. I moved it back to zero for landing and have not gone back to check the angle at the negative position.

Also noticed on the turns at the higher speeds that I only needed to think about moving the stick and it went. Before I had about 1 to 2 inches to make it move into the bank.

I have not done a secound flight as it decided to go winter on us(snow, rain, wind) and they say till friday so maybe saturday we can try again.
I'm just like a kid with a new toy at Christmas.

SaintAero
10-08-2009, 06:07 PM
Nice work with the engine mod. I suspect that the Aero Engineers will tell you that you increased the horsepower considerably.
The equation for this is V2 = V1 * ((P2/P1) E^-3).
To solve for the initial power,
P1 = P2 / ((V2/V1) E^3)
P1 = 110 / ((120/85) E^3)
= 39 HP
The prop is another variable, but assumed constant for the horsepower calculation.
Did the CG change considerably?
Don

wannafly
10-16-2009, 10:27 PM
my attempt at video...first try with the new camera


www.youtube.com/watch?v=iV3iAQStlkA (http://www.youtube.com/watch?v=iV3iAQStlkA)

av8rps
10-26-2009, 06:45 PM
I use 1/2 flaps for all takeoffs and landings in my Kitfox IV amphib. I get an awesome takeoff climb compared to using no flaps. Using 1/2 flaps for landing seems to control my float better, as landing a "shopping cart" on the runway needs one to land a bit faster than if on a regular landing gear.

I also messed around with negative flaps settings (to act as spoilers) and found this through my experimentation; If you get too negative you will find your Kitfox will "fall off the cruise step", especially if at reduced cruise speeds. The airplane will not seem as stable, and you will have to fly faster (at least 75-80 mph TAS was my experience) to keep the aircraft at a flat cruise attitude. When flying with my Highlander buds I irritated them a bit when at their high cruise I kept asking them to speed up if they could, while I was flying around next to them with two notches of flaps on. Anyhow, I readjusted my flaperons so that the indicator shows neutral when I am at my maximum cruise speed. I've put 250 hours on it since and have been real happy with my flap setting. I also now can fly next to slower airplanes without falling off the cruise step. My Highlander (and Rans) buddies appreciate that...;)

Paul S

wannafly
11-27-2009, 10:59 PM
well we have put on about 10 hours and have a whole new love for my Kitfox. Filled it up to full gross weight. Climb is still 11-1200 fpm and no problem maintaining 110 mph cruise at 4000 rpm. Have had it up to 130 mph and it feels solid but since max cruise is called to be 110 we will keep it there for now. Will continue to see what fuel burn is and most of all have fun. Have not felt so excited about flying since I got my license. What a gift:D
will start a panel upgrade next...fun fun

Pilot4Life
11-28-2009, 06:24 PM
What an exciting time! I am very jealous! Those of us still waiting to build are now more anxious, thanks! JK, I hope that my experiences and yours to come are even better as the years of Kitfox flying continue!