[SARPLT]

I have not seen a thread on this model so I thought it would be a good idea to start one to capture some experiences on upgrading the stock model. I picked up this model last fall from one of our readers with the intention of upgrading the power to an 8S fan as many reviews indicate it is under powered on 6S. My thread on 6S vs 8S highlights those experiences. Another modification that seems to help the performance is to cut back the intakes to open them up to allow more air in as they close in at the lip. I have used green tape to show the area that will be cut back.

After much trial and error I decided to go with a CS12 blade fan matched to a Typhoon 1680 KV motor on 8S to get the thrust required over the stock 6S fan (3.49kg thrust on 8S). The stock CS fan housing had to be cut down in length to fit into the same location (photo shows stock alum housing compared to CS housing). This CS fan and motor combination is actually 22 gs lighter than the stock Freewing 6S setup but unfortunately this weight savings will be lost with the addition of the larger YEP 120 HV ESC over the stock 6S ESC.

Marty

[4stripes]

Looks good Marty!
When you get a chance try measuring the static thrust in the plane (you might be shocked at how much is lost in the airframe).
Please post your results.
Just thinking out loud but I think the 1680kv is way too high KV for 8S. That is pretty much a typical 6S number, or even slightly hot 6S motor for that fan (or FW fan for that matter).
Something is limiting your full wattmeter readings is all I can figure. If for some reason the ESC is limiting full power the extra watts are creating extra stress on the ESC so 120amp ESC may be pushed harder than desired.
Good luck

[SARPLT]

Ok thanks. I am still going to play around with the YEP programming to see if I can make any changes to the output. Can you please post the CofG for this model so I can keep an eye on this as I install the ESC and battery position. I did not get a manual. I will have to try to track one down on line.

[4stripes]

Here is the manual link from MotionRC
https://cdn.shopify.com/s/files/1/10...39208637900150

You did make substantial improvement in output since your early post so some settings must have stuck.
Have you tried to increase your end point adjustment as posted earlier? Just hook up the wattmeter first and watch the output as you ramp up the number.

[SARPLT]

Thanks. Not sure what you mean by end point. I have tried different throttle adjustments and timing with no difference. I did notice that after I save the numbers using the ESC program card the cell number is defaulting back to 6S after I save 8S. When I run it the meter numbers are still the same compared to that using the HET 100 amp ESC so this does not seem to make a difference. I did notice that after I cut the length of the CS shroud and reinstall the fan and run it, the thrust was reduced to 3kg for the same numbers. I will keep playing with it tomorrow. Since the current is so high I may try the other fans in this CS shroud and see what kind of results I get.

[4stripes]

End point travel adjustment is same for all channels including throttle. Normally 100% each way but you may find some hidden power by selecting say 109% at the upper end.
Having 6s programmed won’t make any difference except your LVC or low voltage protection will not be accurate at the end of your battery run. The fact that that isn’t sticking tells me the programming isn’t done right or the ESC is not remembering and is therefore defective.

[SARPLT]

Unfortunately catastrophic results today. I increased the throttle travel from 100 to 140% in 10 increments with no significant change in thrust (average 2.9kg) or increase in meter readings (127 amps, 3200w). After the fourth run after resetting the travel back to 100% I did another run up to check final readings. As I was going through about half throttle the fan exploded. Most of the blades came out of the front as expected with one wedging itself in the drywall and the shroud spreading outward. The shaft on the motor also sheared off. Fortunately no damage to anything in my shop or myself but there is plastic every where. I guess I pushed the CS fan past its limits as it was perfectly balanced. OK I have learned my lesson and decided to stay with a metal shroud fan for future 8S setups. Going to park this project for a while and move onto something less dangerous until I decide which fan to buy.

Marty

[4stripes]

If it was heavy type it should not have exploded. What likely happened is your perfect balance got thrown off by the fan shifting position. If it rotates on the adapter at all the Dynamic balance goes out the window and all he’ll breaks loose.
Glad you were not hurt.

Just curious, where did you buy the fan?

Another question, did the ESC ever cause some roughness in operation during throttle changes? Sometimes that roughness creates momentary stoppages forcing the fan to stop and go suddenly twisting the rotor out of position on the adapter.

[SARPLT]

It was an HK fan. The YEP ESC seemed to work fine throughout the throttle range. I am wondering if cutting down the shroud length may have weakened it. The adapter was securely fastened to the broken shaft so I do not think anything came loose.

[4stripes]

It isn’t the adapter that shifts. It is the rotor assembly shifting on the adapter.
As for HK I stopped using their CS fans after the half dozen failures from one bad batch. I tried an order over a year later and they were still selling the weak fans. At least I could use their shrouds and other adapter parts.
As for shortening the fan shroud, that wouldn’t have caused the rotor to be so imbalanced as to hit the shroud or snap the motor shaft. Only a big imbalance or thrown blade would do that. Now that you said it came from HK, I am not really surprised. It was likely a lighter plastic version.
My weights were of the rotor and end alloy washers only (no spinner or adapter). 51g plus is good, 49g no good.