Protos setup - some issues - hopefully taken care off

[HarryR]

I have been working on getting this heli to a maiden flight . The heli was rebuild on a Fusuno Carbon / plastic frame ( really AWESOME LOOKING) and it came with a brand new YEP 100A. So I decided to add an AR7200BX to it as I am familiar with this unit (having other Protos and 450X running with this one). The other Protos flies nicely (it has an ALIGN ESC and the Governor store is active) so I know the combo works. I did the mechanical and the electronic set up TWICE if fact, as well as the YEP 100A (set with governor store).
So I go to the field to see of all the pre-take off stuff seems to be working correctly. I spool up the heli to about 50% (Throttle curve 0-55-55-55-55 in Normal, 65-65-65-65-65 in Idle up and Pitch Curve linear 0-25-50-75-100 for both Modes). Everything looks good. Increase throttle to just over 55%, the heli starts to lift but something does not seem right so flick on the THOLD and the heli jumps in the air for about 1-2 feet, the motor cuts out (result of the THOLD I am sure). So I tried this a few times and every time the heli jumps after I shut the heli down (either throttle to zero or THOLD). So, over the last weekend I checked and rechecked all the settings to make sure I have the MIN And MAX Throttle confirmed in the YEP 100A and I went flying again. Same result. The heli POPS in the air after I shut down the power. Almost like a last surge of power before the motor shuts down.
Something is not right .What should I be looking at?? I am thinking of perhaps disabling the GOVSTORE and just have the throttle completely "in charge of the motor" to see if that makes a difference. I am also thinking that this may have nothing to do with the Protos but everything to do with the electronics which means that there might be a setting-conflict somewhere.
So I checked that out. My TCurve is linear -100 to +100 my idle up was 65-65-65-65--65 across. I do not think I got to the Idle up setting during these spool-ups so I do not think that is the issue. I did redo the complete YEP 100A set up and I am thinking something that was mentioned by two other members might have been the issue. Seems that the mfgs are suggesting you do the Initial basic set up for the ESC using the stick method which really is setting the MIN and MAX. Then, you unplug and get the PROG CARD to complete the 2 pages of the program. AND THEN. The last step is to unplug everything again, followed by a 100 percent spool up. I did not do that last part because if you look at the Prog card there is a STOP and MAX function (bottom line on page one) and I basically ASSUMED .. Yes. I know :-( that this would be the only thing you have to do... after all the Prog card is the prog card he?? However that is not the case.. So that last step is to spool the motor up to 100% to "teach" the system where the MAX revs (head speed) are going to be. That will be the level that is being set. So I did all of that (with all blades off). As a check, I then reset the TCurve to 0-55-55-55-55 (idle up (1) is 65 across and idle up (2) is 75 percent across and spooled up (again without blades of course). The result was :
1/ the motor runs at 55% , throttle stick has no impact once you are at 55% or above.
2/ up to Idle1, motor kicks up (audible change to motor speed)
3/ up to idle2, motor kicks up again audible.

Reducing throttle and / or flipping the THOLD switch did not show anything weird. So I hope that was the issue

During this three week long exercise I also felt that the interaction between the main drive and the tail was not smooth. I took the tail off and the belt from the drive pinion and main gear and "hung" the tail from a screwdriver so I could see if there was perhaps a TWIST in the belt. Sure enough the belt was twisted!!!. I reinstalled the belt and set the tensions and darn it .. that drive train runs now completely silky smooth.
Now I am thinking that the POP UP of the heli ( see earlier in this post) was a result of the belt getting caught on spool down. Next week-end. I hope to be able to get the beast in the air.
I just wanted to write the complete story so some other poor soul avoids this issue!!

[Mikej]

It sounds like your Pitch Curve in throttle hold is giving you positive pitch, change to 50,50,50,50,50 and see if that sorts it out

[dr dremel]

Yeah I thought TH pitch curve and IU pitch curves did not match. But solved anyway?!

[HarryR]

I think it was the belt twist that made the model pop up in the air on spool-down but I am not sure