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Apr 23, 2018, 01:53 PM
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FMS F-16C (70mm EDF) Maiden Report


Another successful maiden to report. Two flights of about 3:30 each on one 6s 4000mAh bat. Both landings seem smooth from my perspective, but from the 3rd person view atop v. stab. , seemed more harsh.

Aerobatic flight CG at 110mm
motionsic's F-16 flight (5 min 6 sec)


Maiden Video with CG at 95mm
Copy of FMS F-16C 70mm EDF Maiden (4 min 48 sec)


2nd flight video with light aerobatics, CG at 105mm
Copy of F 16 2nd FLT (4 min 29 sec)


The good:
1. really robust and handsome CNC retracts, rolls true with no play.
2. digital metal gear servos are strong and center very well, already centered out of the box
3. ESC, motor, fan adequate for sport flying and sounds pretty good.
4. many thoughtful details like flexible nose, plastic LEX and intake lip, small parts count that are evident in unboxing/build videos.


Need improvement (the bad - though this could be my personal preference for neutral feel):

1. Recommended CG of 95-105mm is way nose heavy. I balanced mine at 95mm and almost could not rotate before the end of my runway. Just doing a finger push at tail in the pits to test how much force is required to rotate felt excessively nose heavy relative to main gear location. Basically impossible to hold a wheelie like the real one does.

2. Inflight behavior also felt nose heavy as pitch trim varies a lot depending on speed. A well balanced sport plane should require little trim change for vast speed ranges, only pitching down slightly for approach speed; not the case for this FMS F-16. Also inverted nose drop is fast, needing a lot of elevator push to hold level inverted flight.

3. Airplane is super stable, which also results from nose heaviness and the large negative incidence angle of the h. tail to counter it. Not really characteristic of nimble F-16. Should have been designed with more symmetric airfoil and minimal h. stab incidence angle, in my opinion.

4. With 6s 4000mAh 60c battery, I cut out another 1/2" of foam to move battery back (rear strap holding front of bat) and still could not achieve forward CG of 95mm. I added a Mobius camera (47grams) on the vertical stab and 3/4 oz (21 gram) of lead to air brake location to achieve 105mm. So I recommend limiting your battery size to achieve proper CG.

The Ugly
1. wish the finish was more heat resistant. The foam under the canopy has started bubbling in ambient temp of less than 80deg F (sunny) , in less than 5 min, even with stock vent hole and I drilled 3 more on the canopy. I rush to retrieve plane after flight and put it under shade. Will be doing a Edwards or some lighter scheme for heat tolerance and visibility.
Last edited by turbinefancy; May 14, 2018 at 12:09 PM.
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Aug 11, 2019, 07:07 PM
Registered User
Quote:
Originally Posted by turbinefancy
Another successful maiden to report. Two flights of about 3:30 each on one 6s 4000mAh bat. Both landings seem smooth from my perspective, but from the 3rd person view atop v. stab. , seemed more harsh.

Aerobatic flight CG at 110mm
https://youtu.be/soXIcWAqxlk

Maiden Video with CG at 95mm
https://youtu.be/hwvkyRjNh1g

2nd flight video with light aerobatics, CG at 105mm
https://youtu.be/uB1_CiR9pqk

The good:
1. really robust and handsome CNC retracts, rolls true with no play.
2. digital metal gear servos are strong and center very well, already centered out of the box
3. ESC, motor, fan adequate for sport flying and sounds pretty good.
4. many thoughtful details like flexible nose, plastic LEX and intake lip, small parts count that are evident in unboxing/build videos.


Need improvement (the bad - though this could be my personal preference for neutral feel):

1. Recommended CG of 95-105mm is way nose heavy. I balanced mine at 95mm and almost could not rotate before the end of my runway. Just doing a finger push at tail in the pits to test how much force is required to rotate felt excessively nose heavy relative to main gear location. Basically impossible to hold a wheelie like the real one does.

2. Inflight behavior also felt nose heavy as pitch trim varies a lot depending on speed. A well balanced sport plane should require little trim change for vast speed ranges, only pitching down slightly for approach speed; not the case for this FMS F-16. Also inverted nose drop is fast, needing a lot of elevator push to hold level inverted flight.

3. Airplane is super stable, which also results from nose heaviness and the large negative incidence angle of the h. tail to counter it. Not really characteristic of nimble F-16. Should have been designed with more symmetric airfoil and minimal h. stab incidence angle, in my opinion.

4. With 6s 4000mAh 60c battery, I cut out another 1/2" of foam to move battery back (rear strap holding front of bat) and still could not achieve forward CG of 95mm. I added a Mobius camera (47grams) on the vertical stab and 3/4 oz (21 gram) of lead to air brake location to achieve 105mm. So I recommend limiting your battery size to achieve proper CG.

The Ugly
1. wish the finish was more heat resistant. The foam under the canopy has started bubbling in ambient temp of less than 80deg F (sunny) , in less than 5 min, even with stock vent hole and I drilled 3 more on the canopy. I rush to retrieve plane after flight and put it under shade. Will be doing a Edwards or some lighter scheme for heat tolerance and visibility.
I don't want to be annoying but, this plane is designed for a 3300 mAh battery, I think a 4000 is a little bit heavy......

Good job by the way, lots of useful information in your post
Sep 07, 2019, 09:58 AM
Registered User
I fly mine with 3300 and dint have any issues only fee clicks up not very nose heavy


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