250 Blade balancing
- Thread starter crashbash
- Start date
Ricardo
New Member
Hi Lee, I allways balance my blades since they came home, any size, and I'm using now in my Trex 250 some blades I get from HobbyKing the Turnigy carbons, they are awesome and balanced they are really smoth. Perhaps that's why I feel more comfortable flying the 250 than any other of my helis....Well after the Trex 500 FBL of course, the bigger the easier.
Congratulations.
Congratulations.
zenmetsu
Member
My apology for the thread necromancy...
I have a pair of carbon fiber blades and I found that they were off by a fair amount. Luckily my other hobby is chemistry so I have an electronic balance that is accurate to 1/100g. I found that one blade was 7.90g and the other was 7.81g. Sure, 98.9% matched, but there was a noticeable amount of vibration. I taped the wing and got the COGs dead on, both blades sitting at 7.90g now.
I still have some vibration when spooling up, but this could be due to the blades not yet being pulled straight due to centrifugal force. I have balanced the flybar as well, but it didn't help much. Overall it is noticeably smoother than it was before balancing the blades.
The big issue I have is with blade tracking. It is spot-on at the moment, but if I swap the blades (like put them in the opposite grip), it goes about 4° out of tracking. Maybe there is something amiss with my blades after all.
I have a pair of carbon fiber blades and I found that they were off by a fair amount. Luckily my other hobby is chemistry so I have an electronic balance that is accurate to 1/100g. I found that one blade was 7.90g and the other was 7.81g. Sure, 98.9% matched, but there was a noticeable amount of vibration. I taped the wing and got the COGs dead on, both blades sitting at 7.90g now.
I still have some vibration when spooling up, but this could be due to the blades not yet being pulled straight due to centrifugal force. I have balanced the flybar as well, but it didn't help much. Overall it is noticeably smoother than it was before balancing the blades.
The big issue I have is with blade tracking. It is spot-on at the moment, but if I swap the blades (like put them in the opposite grip), it goes about 4° out of tracking. Maybe there is something amiss with my blades after all.
nitro208ca
Member
With my rogue 500 I dont have to worry about that.I guess i got luck.I wieghed them on to different scales and came out with the same weight and balance at both places.I got REAL LUCKY
zenmetsu
Member
Straight as an arrow. I replaced the feathering shaft with one from Align because I heard that they were less likely to pull apart. After I had the elevator ball pop off and the heli smacked into the ground, I took the feathering shaft out and rolled it on glass to make sure that it was OK.
If I spin up the head without the main blades, it is fine (well, nothing over 30% throttle, I don't want to overspeed the head due to lack of loading). The vibration is more of a wobble... the whole heli seems off balance until the head is doing at least 4-5 revolutions per second. It only affects starting, so it might not be a big deal. I might toss a video online to demonstrate what I am talking about if this is abnormal.
zenmetsu
Member
I think that I found the problem... rotor housing appears to be wobbling ever so slightly. I'm going to pull the head and make sure that my main shaft is still true.
The rotor housing on these 250s appear to have an issue with the way they attach. There is very little engagement with the main shaft and if there is any play, the head is free to wobble using the head screw as a pivot point. :/ The rotor housing is split where it engages the main shaft, and the engineer in me is having a hard time understanding why. I may need to "tighten" the housing by flexing the two halves inward to take up a little slop.
One good thing about this hobby; it is definitely brushing up my mechanic skills.
The rotor housing on these 250s appear to have an issue with the way they attach. There is very little engagement with the main shaft and if there is any play, the head is free to wobble using the head screw as a pivot point. :/ The rotor housing is split where it engages the main shaft, and the engineer in me is having a hard time understanding why. I may need to "tighten" the housing by flexing the two halves inward to take up a little slop.
One good thing about this hobby; it is definitely brushing up my mechanic skills.
Lee
Well-Known Member
If you say its just wobbling on spool up then make sure your blades are not too tight in the grip. They should stick out when the heli is on its side but flop doen with a slight tap. Before spooling up give them a little pull out to make them almost straight then you don't need to wait for centrifugal force to do it for you.