Blade 400 First Crash, Some Questions

[topquark41396]

It finally happened. On my tenth flight, as soon as it left the ground the pirouette started and it was all over in a couple of seconds. Slammed it into my (very substantial) grill. Luckily, nobody got hurt - thank goodness for my strict rule of people having to stay inside while I fly in the backyard!

Can't figure out why the tail took off like that with the stick centered. Spooling up seemed fine. Maybe the gyro went wacky?

Anyway, my questions:

1) Is is possible in a crash to strip the inner gear(s) of the micro servos that control roll? They buzz something awful now, until I push a spindle arm with my finger.

In the crash, the blades stopped almost instantly, but did not break. Bent the spindle/feathering shaft that aligns the main blades, so that one blade was dipping about 15 degrees below horizontal.

2) There was a very slight bend in the flybar that I was able to straighten out. Should I just replace it?

If I throttle up with the main blades removed (and the bent spindle), the flybar and paddles track fine, and the roll/pitch seems to work. I wonder that if the main blades were attached, the servos would "skip".

The reason for asking the above is that I am new to this hobby, and the last time I installed servos in an rc aircraft was the late 1980's... back when they were the size and weight of uranium slugs. These new-fangled micro servos leave me scratching my head.

Lastly, any advice of anything else to check would be welcome!

And thanks!

P.S. The grill came out unharmed, so backyard cooking will continue...

[BKF]

I've had a couple minor crashes involving rotor strikes, and both times the cyclic servo controlling roll on the left side had stripped out a couple servo gears.

Sometimes they work, and other times they just whine and slip. Considering that heli's are unstable to begin with, you should replace the gears/servo before you make a correction on the stick only to have the servo slip and do nothing...

The Spektrum DSP75 gears are identical to the E-Flite DS75 servo gears, and are immediately available. It's like 3 bucks for the gear set. Buy a bunch!

[DebianDog]

The Blade 400 is not know for it's resilient servos ;) You will probably have to take them apart and order gears.

I would just trash them and buy "better" ones myself. But that how I roll :)

[carlo_the_wonder_frog]

Digital servos tend to "Buzz" all the time due to their rapid position update speed. Plastic geared servos break on crashes and break easily. Try JR 285MG servos, they are a perfect fit and have strong metal gears in them. Expect to pay around $40 for each. You could also try Hitec HS65MG servos, they are nearly bullet proof but do not fit as well, some grinding might be necessary on the servo holes.

[BKF]

Has anyone tried replacing all the servos with the JR DS285MG servos? I'd really like to replace the DS75 servos, since it seems like in a rotor strike, you automatically lose the gears in at least 1 cyclic servo (at least that's happened twice to me). I've been replacing gears with gears from the DSP75 Spektrum servos which are identical, but I'd rather have metal gears.

I assume as long as you replace all the servos, you'd get equal movement compared to the others, but I don't know if different servos have different "throws" compared to stick movement.

Digital servos tend to "Buzz" all the time due to their rapid position update speed. Plastic geared servos break on crashes and break easily. Try JR 285MG servos, they are a perfect fit and have strong metal gears in them. Expect to pay around $40 for each. You could also try Hitec HS65MG servos, they are nearly bullet proof but do not fit as well, some grinding might be necessary on the servo holes.

[mpetrich]

FWIW, the HS65MG fit perfect and the stock servo mounting screws work with them. No grinding necessary.
VERY nice upgrade.
Matt

[carlo_the_wonder_frog]

Has anyone tried replacing all the servos with the JR DS285MG servos? I'd really like to replace the DS75 servos, since it seems like in a rotor strike, you automatically lose the gears in at least 1 cyclic servo (at least that's happened twice to me). I've been replacing gears with gears from the DSP75 Spektrum servos which are identical, but I'd rather have metal gears.

I assume as long as you replace all the servos, you'd get equal movement compared to the others, but I don't know if different servos have different "throws" compared to stick movement.

Plastic geared cyclic servos break on almost every crash, if you replace the whole servo it must be the same as all the others. Each type of servo has different speeds and mixing different servos on the cyclic will cause all sorts of nasty interactions. 3 of kind is what you need.

[MikeCrasher]

My neighbor came home with a new 400 - having only flown the CX2. He came over to show me the 400. The same size as the TREX450 and uses the EFlite Servos most likely from the CX as well. Having seen the plastic geared servos destroyed - the HS65MG servos as mentioned by Carlo (I use them in my TREX) would be well worth the replacement now. I had found that the plastic gears spit out teeth on one side and you could get away with rotating the main gear 180 degrees, as the servo travel may not contact the area, but go with Metal Gear Servos and don't look back. Mike