What's max rpm for X5 runing 620mm blades

[kkkklee]

I have one strenched X5 runing 550mm blades and I really like it. And I want to put 620mm blades on the other X5. Just curiosity what's max rpm it can run to be safe

[Yfbb]

Integrity handywork ran 2350 with 610s. He had gear stripping issues, but his heli was 3600g and he was running gov with 12s. I would run a relatively tight gear mesh with the black gear to be safe.

[kkkklee]

Now the max rpm I am runing only 1900. Don't want to break the main shaft and spindal shaft because 620mm give a lot more centrifugal force to the spindal shaft that only 6mm in diameter. In worst case blades shot out.
But if integrity can spin his x5 at 2350 rpm with 610mm blades. That X5 shafts are pretty strong. From my calculation 1900 with 620 blades will put 500 pounds of pulling force on the spindal shaft already. My X5 still runing 4020 stock motor and I want to try more floating during auto.

[Yfbb]

With a 4020 you can pretty much do whatever you want and not have failures. The weak point if there is to be one is the main gear. I wouldn't worry much about the spindle though. The weakest point would be the 4mm screws, and the old align 600 spindles used to use the same 4mm screws too.

[kkkklee]

I try to limit the collect pitch to -11 11 and hope the red gear will survive but I will order black gear soon. There are no way to put 5mm spindal screws on it. So pretty much fix.

[kkkklee]

550 vs 620.

[kkkklee]

Another view

[Yfbb]

That 550 one is 12s right? Nice mavrikk blades.

When I went spindle bolt shopping for my 600 I did some calculations. Given the tensile strength and the cross section of a m4 bolt, it will take about 3700 pounds of force to snap a class 12.9 m4 screw.

If there were to be a weak point, it would probably be the main shaft. Even so, Integrity had no issues with the shafts so it looks like your heli should be 100% ok

Edit: I redid the calculation. Its about 3400 pounds.

[kkkklee]

Thanks. That figure help.
One more picture from the tail.

[kkkklee]

Originally Posted by Yfbb

That 550 one is 12s right? Nice mavrikk blades.

When I went spindle bolt shopping for my 600 I did some calculations. Given the tensile strength and the cross section of a m4 bolt, it will take about 3700 pounds of force to snap a class 12.9 m4 screw.

If there were to be a weak point, it would probably be the main shaft. Even so, Integrity had no issues with the shafts so it looks like your heli should be 100% ok

Actually the 550 is running 4025 890kv 6s motor. Plenty of power to spare already. 2300rpm and 13 degrees pitch enough for me to handle.

[OnceYouGoJack]

If your X6 works, next we'll make an NX6 with the OS55

[kkkklee]

Originally Posted by OnceYouGoJack

If your X6 works, next we'll make an NX6 with the OS55

I will get more test flight sooner to see x6 work or not