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Jun 23, 2019, 11:15 PM
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Kwik Fli Mk III Vintage Pattern Airplane Flight Log


I have returned a vintage Kwik Fli Mk III pattern airplane to flying condition.

This is the Graupner version of the airplane - it was very nicely recovered in the original Phil Kraft color scheme by it's prior owner.
The airplane is fitted with an OS 46 AX engine; Mac's muffler; Master Airscrew 11 x 6 propeller; Tru Turn spinner; Hitec Servos; Futaba S3008SB receiver and Futaba 10J transmitter.

After completing break in procedures on the new OS motor today I test flew the airplane.

The first flight was with the engine running very rich to continue breaking it in - just a few laps and figure 8's around the field for trimming. The airplane required minimal aileron trimming and some down elevator.
Trimming and test flying were made more difficult due to 10-15 mph direct cross winds from the north.
Upon landing it was noted that if the airplane carries a little too much speed that it will float and likely require a go-around.
Subsequent flights featured further engine tuning closer to full power. Aileron throw was increased slightly to improve roll rate, rudder and elevator throws were set up properly and did not require changes.
The airplane has excellent vertical and level flight speed - the engine / muffler / propeller combo is correct for this airplane.
Basic aerobatic rolls / loops and stall turns were made in flights 2-5.
The airplane does not spin well (hardly at all) with it's current settings - attempts to experiment with more radical aileron throws via dual rates will be made in the future when the engine is properly tuned / fully broken in and the airplane trimming is complete.
The nose wheel / gear is raked forward - this makes for poor taxiing and is not very forgiving if corrections are needed during takeoff roll-out (I fly off a grass field) I actually resorted to carrying the airplane out to the flight line, aiming it into the wind and taking off straight ahead as opposed to taxiing it.
The airplane does set up for a nice takeoff using just enough up elevator to keep pressure off the suspect nose wheel gear / configuration - it is best to spool up to full power without too much delay to avoid potential issues caused by nose gear.
Tuning efforts were hindered due to the fact the glow igniter actually loosened the the glow plug slightly for flights 3-4 just enough to affect running after about 3 minutes in the air.
The engine still requires some more tuning - top end is good but the bottom end is still to rich. The engine tends to run backwards when hand started and if it is flown too long at low to mid range it will flood the engine to the point that it will die (flight 5 ended in a successful dead stick landing as a result of that) - more pre flight tuning will be needed prior to the next flying session.

5 flights were completed today - things to focus on next time it flies will be carefully tuning engine (low end) and observing the behavior of the nose gear set up.
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Jul 04, 2019, 06:38 PM
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Flights Made On 7/4/19


Had a chance to fly the Kwik Fli again today.

Conditions were favorable with very light 0 - 5 mph winds from the east. Temperatures were in the low 90's with high humidity and scattered thunderstorms.

Flights today confirmed that the trimming from the previous session was good - only minor adjustments were made.
The engine's low end needle was leaned about 1/4 turn on the needle - as a result the engine now has much better mid to low end performance. It also doesn't tend to start backwards when started by hand. The engine tuning is now essentially complete and the engine proved to be both powerful and reliable today running 15% nitro Wildcat fuel.
The nose wheel wasn't much of an issue - it did dig in once on roll out - but the grass at the field was between cuts and is very thick. It is still best practice to spool the engine up quickly and not waste time getting in the air on takeoff roll-out.
I have confirmed that with the 8 ounce fuel tank maximum time in the air should be about 7 minutes. I made a deadstick landing on flight #9 due to running out of fuel and the timer on the transmitter was at the 7:xx mark. That flight was probably flown about 85% of the time at wide open throttle. The deadstick landing was not an issue - the airplane is well balanced and has excellent glide characteristics, I landed it nicely right on the runway.
I may consider fitting a 10 ounce fuel tank in the future - there is room for it and the hatch will make it an easy task.

I also had a chance to fly the Kougar seen in the photos today.
It is a fairly heavy Kougar since the airplane is glassed and painted.
That airplane is fitted with an OS 55 AX, a Mac's tuned pipe and a Master Airscrew 11 x 7.5 propeller.
The Kougar is very fast and flies very well - it will do snap rolls and spins nicely. It does hold onto it's speed on landing due to it's heavy weight -it also needs a well executed takeoff roll-out with the engine spooling up to full power and good airspeed. Attempting to horse it off the ground without sufficient airspeed in thick grass or grass with water ponding can cause it to get a little "snappy / wobbly" when it breaks ground.
I probably need to lean out the low end needle on that engine as well, the engine does load up some in the low to mid range - enough that it can cause the engine to hesitate to come up to full power on the high end - that is not good when taking off.
On the last flight the low idle was unusually high - I will need to investigate that before the next time it flies.

The Kougar made 4 flights today and the Kwik Fli made 5.
Jul 06, 2019, 09:41 PM
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Nice planes and details.
Jul 07, 2019, 10:35 PM
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Flights 7/7/19


Made 3 more flights on the Kwik Fli on 7/7/19.
Wind was from the east at 5-10 mph, temperatures in the mid 80's with fairly high humidity.
The grass at the field is getting thick from recent rain / humid conditions - takeoffs are best with engine spooled up to full power and slight up elevator to keep pressure off nose wheel.
Fuel was changed to Morgan Cool Power 10% - the engine ran on the rich side with this fuel - it could be leaned out a little if it is flown again on 10% nitro.
The airplane will knife edge - the rudder has plenty of throw.
Nothing unusual to note other than a need to possibly lean the engine out a little if it is operated on 10% nitro and some more throw could be added to ailerons - can use dual rates to experiment.
The airplane now has 13 flights on it.

Also flew the Kougar again today when the winds were stronger in the earlier morning behind a passing front.
The airplane had a new throttle servo installed since it broke the mounting tab on the sub micro servo last time it was flown (that caused the throttle to not close completely to idle unless the kill switch was depressed). The replacement sub micro throttle servo was mounted with improvised rubber grommets over the mounting tabs to help dampen any flexing and / or vibration wear.
The airplane ran and flew great until it blew the OS #8 glow plug - will need to fit that airplane with a new OS #8 glow plug next time.
The engine did not run as well with replacement non #8 glow plug - tried to re tune engine for this which was a mistake.
The engine will require re tuning and re installation of a new OS #8 glow plug next time.
The airplane made 3 flights - then one final flight with about 3-4 takeoffs and landings for re tuning.
This is a great airplane for windy conditions.
If it breaks ground early without sufficient airspeed it does drop the left wing some (that only occurred on the 4th flight due to a combination of thick grass and the engine not spooling up completely with full power).
Jul 08, 2019, 01:42 PM
Registered User
Hi got a Kwik Fli III that I built have not flown,has refurbishedHP-61 Gold Cup ABC with SPEKTRUM G-8 with Spektuum servos,I'm experienced,but have not been to the RC club field as I'm on the mend... Hip replacement. Any pre flight suggestions,as You are out there flying, don't laugh staying current flying my E Flite UMX micro P-51 in big lot in front of house.
Jul 08, 2019, 07:48 PM
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Hello Fast Ruchard,

The Kwik Fli's flight characteristics are somewhat similar to a Kaos pattern airplane if you have flown one.
In comparison to a Kaos the Kwik Fli is a little more stable and docile with it's larger wing.

One big difference between the 2 airplanes is the ailerons. The strip ailerons on a Kaos require hardly any throw to be effective - the barn door type ailerons used on the Kwik Fli require considerably more throw to be effective.
When test flying I would suggest using dual rates for the ailerons - set your base setting more conservatively and your dual rate with more throw / more aggressive.
When I test flew mine I essentially set all my control throws the same as one of my Kaos airplanes - that worked great for the rudder and elevator, but the ailerons did need some more throw. I am still experimenting with adding more aileron throw.
I always set rudder throw fairly aggressive / high throw rates on all of my airplanes.
Setting the elevator similar to the setup for a Kaos .40 worked great.

I see your nose wheel / gear is straight and is not raked forward like mine - that is great, DO NOT RAKE THE GEAR FORWARD LIKE SEEN IN THE PHOTOS ON MINE.
I have learned to use my nose gear as it is - I hold slight elevator up on takeoff rollout to keep some of the pressure off the nose wheel and take care not to try to correct course deviations too much with the rudder. The raked forward set up tends to dig in and make the airplane want to tip over like a high wing trainer - you won't have to worry about that with yours.

I have an 8 ounce fuel tank in mine - you have a larger displacement .60 size engine that will consume more fuel. The fuselage should fit a 10 ounce fuel tank, I would use one that is at least that big in your case.

Like a Kaos the airplane has excellent glide characteristics - dead stick landings are not an issue, just keep the nose slightly down to maintain speed.

I have the CG set on mine like it is in the plans that can be seen on the outerzone website - flight characteristics are good with that setting.

This airplane compares favorably to a Kaos - it rolls a little more slowly and is slightly less aerobatic but it tracks like it's on rails and maintains level heading excellently through slow rolls if minimal down elevator is applied while inverted. In comparison to a Kaos the airplane tends to float and slow up just a little more on landing.

If you've flown Kaos pattern airplanes you will feel right at home flying this airplane.

There are some links below to the outerzone website that has a lot of good info on the Kwik Fli - download the plan and instruction PDF's on the site for future reference. (They're toward the bottom).
https://outerzone.co.uk/plan_details.asp?ID=4440

Here's a link to Tower Hobbies set up for a Kaos 40 - use the throw suggestions for the elevator. You can make the throws for the rudder a little more aggressive and I would add some more throw to the ailerons (use dual rates).
https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXZT80



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