FT Mini Arrow

[andrej]

I've flown a bit more and noticed a slight tendency to nosedive occasionally. As I said, the elevons are raised even more than they should be. When gliding without a motor, I also have to raise the elevons quite a bit. Maybe it would be worth moving the CoG back 5 mm?

 

[Mr Man]

I've flown a bit more and noticed a slight tendency to nosedive occasionally. As I said, the elevons are raised even more than they should be. When gliding without a motor, I also have to raise the elevons quite a bit. Maybe it would be worth moving the CoG back 5 mm?

Yeah, sounds a bit nose heavy 👍

 

[andrej]

The motor angle should be zero, right? Maybe mine is angled a bit downwards, I'll have to check. Did someone make the power pod longer so the motor extends further from the trailing edge of the wing? Otherwise, if I install an FPV, the nose will be extremely heavy. There's also the risk that in a crash, the battery will move forward due to inertia and break the camera...

 

[andrej]

I moved the CoG back 5 mm, but nothing changed. The wing still dips slightly with the motor, but without the motor, it pitches down at a steeper angle. I don't understand if this wing is so poorly designed, or if making it from 6 mm Depron introduced some unforeseen changes that affected the flight.
What surprised me was that the plane climbs vertically very well and doesn’t tend to drop its nose.

 

[Foamforce]

I had really good luck with the Arrow. Mine didn’t have any bad tendencies.

You said you had to add more reflex than was designed in. That seems to indicate that you’re nose heavy. At higher speeds, the extra reflex will keep the nose up. At lower speed, there’s less air over the elevons so they’re less effective and your nose dips.

I would just try to continue moving the COG back until it starts getting squirrelly, and then bump it back forward until it’s comfortable again. Most FT planes have a pretty conservative COG, so if you’re a somewhat experienced pilot, you can move it back safely.

 

[andrej]

As I understand it, if the CoG is moved back to the tail from the recommended CoG, the nose will be light by default, since the tail is too heavy. At full throttle, it also lowers the nose, even with extra reflex.
Yes, I'll try to move the CG back even further. I just need to find a heavier weight. I already have a 10-gram nut attached to the tail under the motor.

 

[Foamforce]

As I understand it, if the CoG is moved back to the tail from the recommended CoG, the nose will be light by default, since the tail is too heavy. At full throttle, it also lowers the nose, even with extra reflex.
Yes, I'll try to move the CG back even further. I just need to find a heavier weight. I already have a 10-gram nut attached to the tail under the motor.

What you move the COG back, you should reduce the reflex because not as much will be needed to keep the nose up. Because you have less reflex, the throttle won’t raise the nose as much.

 

[andrej]

I changed the motor mounting angle so that it pushes the wing up, slightly increased the reflex, and now with the motor it flies horizontally without diving.