When I first built this plane I was so excited because I love flitetest and I like park jets. I was stoked to fly and build a flitetest park jet. As per per all the other flitetest planes it when together perfectly and looks awesome.
but then I started to try to get the cg where it was marked. hmmmm did I do something wrong? No but I did have to shove the 1300 mah 3cell way back and up on the shelf in the rear of the fuse. I figured ok well that's not so bad. but then I started thinking, I cant fly a bigger battery. I'm stuck using the 1300 which is fine I can get 7.5 minutes on a 1300 mah battery and my 2212-10 1400 kv rctimer motor on an 8x4 prop. but I only have 2 of those bateries so now I'm limited on how many flights I can do.
So with the cg set up where it was marked on the plan, I set off to do the maiden. As soon as I tossed it I knew, I was super nose heavy. now I was kind of bummed. I had to fly with constant up elevator just to fly level. which made it fly slow and really unstable, making it stall in turns and falling out of the sky if you let off the throttle, It just would not glide more than a few feet. after three days of trying to get it to fly right, which included added weight to the rear I decided I'd had enough and it was time to make a few changes to this great looking plane to make it perform like it looks.
So with my park jet knowledge, I set out to fix the issues.
First to fix the cg problem and make it so I can put the battery more in the middle of the fuse. This will make it possible to run bigger batteries if I wanted, aswell as making the plane handle much better. My plan of attack was to get more weight to the rear, and here is how I did it.
1. I added 1" to the rear of plane pushing the rudders elevons and the trailing edge of the main wing back.( This added a little more wing area as well).
2. I moved the motor and prop back 2". basically as close to the rudders as possible. this also made me extend the turtle deck on the fuse, which I needed for support when I change the motor mount.
3. I moved the motor to inline with the wing, and changed the motor mount to the regular flitetest fire wall.
4. I moved the servos back 3". Shifting weight with the adde bennifet of shortening the control rods .
5. I also moved the leading edge of the wing forward 1". This added more wing area with out changing the overall look, and I also changed the wing tips slightly to add a bit more wing area.
So after a few monor mods what where the results?
WOW. this thing fly's just amazing. No up trim for level flight. Glides for days. Doesn't go nose up in the turns resulting in a stall. The plane now flies slow with lots of control. It's als much faster with the same motor and battery. speaking of battery, now it's towards the front of the fuse. Which means I can now fly with a 1300mah 1800mah or a 2200mah battery. The cg is exactly where it was marked on the original plans. I was actually able to increased the throws and reduced the expo. let me explain why I could do that. On the original plane everything was stuffed in a length of about 12" battery to motor. Now the weight is spread out over 18 " battery to motor. This slows down the movement of the plane making it less twitchy and able to transition slower making it fly much smoother with much more control.
(Below) here you can see the extended under plate and the servos moved back.
(Below) you can see how far back the servos are from the original.
(Below) This shows the extra length and the extended turtle deck. You can also see the the motor pushed back and the new motor mount.
(Below) you can see how much further forward the battery sits. This is balanced on the original cg marks.
So if you build this plane and it doesnt work out the first time. I encourege you to build one using my changes. Please If you need help or have any questions,check out the forum posted below about these changes . Don't forget to report back on the forum aswell.
these plans are currently untested. if you build off my plans and find a problem please let me know so I can correct them. I also added 1.5 degrees of toe in to each rudder this should increase the slow speed turn stability even further.
also the build on mine is a little different.
1. the elevons are now part of the air frame for more durability
2. this also adds a glue spar in the main wing use flitetest methodes for glueing this together
if you need a build video I could probly throw one together if needed. but its a pretty easy build.
I hope you find this use full and it encoureges and inspires you. Don't be afraid to make a change if a plane doesnt fly right after you've built it to the original specs. Modifying is the greatest aspect of this hobby and can be the most rewarding. Good luck.