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Kitfox scratch build

TDL

Active member
#1
My son had been solo on my old Tachone EPP trainer (bought in 2012) for about a month now and it got beaten up pretty badly. EPP planes fly like a kite in 6mph+ wind so I was thinking building a bigger trainer that would fly in the wind for him. I had built a 130% FT Commuter but it flew too fast for my son so I decided to build a bushplane. I always like Kitfox therefore a Kitfox it is.
I found a drawing of Kitfox IV on internet so I started designing the plan on LibreCad. Originally I tried to be as scale as possible, but then I thought about the purpose for this build : a robust trainer for my son, so I skipped some details on fuselage; also the ailerons are simplified. From the start to finish was six nights, the result is: 48” wingspan, 12x6 prop powered by 3542 kv1000 & 3s 2200. AUW is about 36oz.
 

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TDL

Active member
#3
The maiden did not go well, tail heavy combined with a faulty ESC, lost power and crashed on a fence. A new power pod and cowling she was good again. However I was amazed by the cheap Gyro I installed. This plane was extremely tail heavy at maiden but Gyro smoothened her to fly-able. The next couple of attempts were pretty bad, lost control within 5 seconds after taking off every time. I started thinking about Gyro interfering but I would like to give her one more try. So last night while I was gluing my fourth cowling and I finally found the problem- bad receiver! I did a range test and all I got was about 100ft! I put another receiver in and today she flew!
 

BATTLEAXE

Well-known member
#4
The maiden did not go well, tail heavy combined with a faulty ESC, lost power and crashed on a fence. A new power pod and cowling she was good again. However I was amazed by the cheap Gyro I installed. This plane was extremely tail heavy at maiden but Gyro smoothened her to fly-able. The next couple of attempts were pretty bad, lost control within 5 seconds after taking off every time. I started thinking about Gyro interfering but I would like to give her one more try. So last night while I was gluing my fourth cowling and I finally found the problem- bad receiver! I did a range test and all I got was about 100ft! I put another receiver in and today she flew!
Nice on the Kitfox flight. I like how axial the rolls are. Is it the flight controller that is making the wings shake trying to compensate for the tail heaviness?
 

TDL

Active member
#5
During my continuous trouble shooting attempts. I also decided to enlarge the control surfaces, 100% on Ailerons and 40% on Elevator and Rudder. So now she is very sporty! But, my bad luck continued, on the remaiden flight today, one wheel fell off, so she nosed over at landing. I did not think much of it, just put the wheel back and then Round 2 as the video shown. As soon as she took off, you can hear the weird motor sound, but my son thought that’s cool so I kept flying. The gyro was working like crazy, you might hear I was flipping the switch back and forth to reset the gyro. Finally I decided just flying without gyro. The wind was about 10 mph and kept changing direction, so my landing was hot because she was along the wind. After she landed I found the motor was total loosen. No wonder gyro was working crazy to compensate the vibration. Luckily I got her back in one piece.
 
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TDL

Active member
#7
Nice on the Kitfox flight. I like how axial the rolls are. Is it the flight controller that is making the wings shake trying to compensate for the tail heaviness?
Today the CG is right on. The roll rate is good given these huge ailerons. You can see me doing rolling harrier at half throttle toward the end of that clip. She is a fun plane, my son might not have a chance to fly her! Hahaha
I was puzzled by the shake at the beginning . It was due to the loosen motor mount.
 
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BATTLEAXE

Well-known member
#10
Today the CG is right on. The roll rate is good given these huge ailerons. You can see me doing rolling harrier at half throttle toward the end of that clip. She is a fun plane, my son might not have a chance to fly her! Hahaha
I was puzzled by the shake at the beginning . It was due to the loosen motor mount.
Yea it looked like it was having a seizure lol. I noticed it then I had to look again, thought it was my eyes playin tricks
 

Figure9

Well-known member
#11
The maiden did not go well, tail heavy combined with a faulty ESC, lost power and crashed on a fence. A new power pod and cowling she was good again. However I was amazed by the cheap Gyro I installed. This plane was extremely tail heavy at maiden but Gyro smoothened her to fly-able. The next couple of attempts were pretty bad, lost control within 5 seconds after taking off every time. I started thinking about Gyro interfering but I would like to give her one more try. So last night while I was gluing my fourth cowling and I finally found the problem- bad receiver! I did a range test and all I got was about 100ft! I put another receiver in and today she flew!
Wish I could fly a tail heavy like that... :oops::cautious:(y)
 

TDL

Active member
#12
Wish I could fly a tail heavy like that... :oops::cautious:(y)
Sorry that I should be more clear that the video above recorded the 2nd flight of remaiden. The CG was correct. The problem was a loosen motor mount, the weird thing was, once I turned off the gyro, the vibration was gone.
Here is a video from one of many attempts at the actual maiden, extremely tail heavy and half of the elevator was blow off at 5 second into the flight. You can see the gyro took control over there as nothing happened, and then the receiver lost signal around 8 second. The plane went into self balancing mode (motor off), kept flying straight until she stalled and crash landing herself. I was amazed by how the gyro work.
 
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Figure9

Well-known member
#13
Sorry that I should be more clear that the video above recorded the 2nd flight of remaiden. The CG was correct. The problem was a loosen motor mount, the weird thing was, once I turned off the gyro, the vibration was gone.
Here is a video from one of many attempts at the actual maiden, extremely tail heavy and half of the elevator was blow off at 5 second into the flight. You can see the gyro took control over there as nothing happened, and then the receiver lost signal around 8 second. The plane went into self balancing mode (motor off), kept flying straight until she stalled and crash landing herself. I was amazed by how the gyro work.
I say, “It’s a good landing if it doesn’t explode in midair.” o_O:ROFLMAO:
 

TDL

Active member
#14
I say, “It’s a good landing if it doesn’t explode in midair.” o_O:ROFLMAO:
Your avatar reminds me my old 55” balsa J-3 Cub, I was flying her at school yard next to my house, my neighbor’s kid walked over and asked if he could try it. I said okay, explained the basic control, brought the plane to three-mistake height and handed the TX over, thinking nothing could go wrong since the Cub would self level and glide for quite a while, I would have plenty of time to take over control if needed. Wrong!!! the first thing he did was a steep dive at full throttle to one mistake hight and then pull elevator full up, the poor wood wing spar could not handle the abuse, wing fold in half and the plane went straight into the ground, full speed like a dart, Lipo fire and a big hole in the dirt....the whole thing happened within 10 second. But since it exploded on the ground, not midair, I would consider that a good landing too!
 

Figure9

Well-known member
#15
Your avatar reminds me my old 55” balsa J-3 Cub, I was flying her at school yard next to my house, my neighbor’s kid walked over and asked if he could try it. I said okay, explained the basic control, brought the plane to three-mistake height and handed the TX over, thinking nothing could go wrong since the Cub would self level and glide for quite a while, I would have plenty of time to take over control if needed. Wrong!!! the first thing he did was a steep dive at full throttle to one mistake hight and then pull elevator full up, the poor wood wing spar could not handle the abuse, wing fold in half and the plane went straight into the ground, full speed like a dart, Lipo fire and a big hole in the dirt....the whole thing happened within 10 second. But since it exploded on the ground, not midair, I would consider that a good landing too!
Oh, heck yeah! Perfect one pointer! Hence my forum ID ~ ‘Figure9’