Exi 500 CF build (Overdue!)

[Gabe]

None yet, but I will get some!

Los a screw onthe rudder servo mount yesterday and I guess the tail rotor must have caught the ground cause I stripped the belt drive gear again. She is on the shelf until I get back from Philly on Wednesday. Still haven't checked the elevator pitch yet either. Oh well, guess I should focus on my job for a few days

[akent]

Bummer on the stripped gear, but at least it didn't cause a crash!

I flew my 500 tonight and smiled the whole time. I've been flying and debugging the ES600 forever, it seems. The 500 is still my favorite by a mile.

Good luck in Philly!
Kent

[Gabe]

Oct 4, 2009 14:03:17 GMT -6 McKrackin said:

How did you check cyclic?

For aleron...Turn on throttle hold.Power up the heli.Apply enough throttle to get zero pitch.Turn the blades 90 degrees to the heli and boom.Apply full right aleron and check the pitch on the left side.Apply full left aleron and check pitch on the right side.

For elevator...Turn the blades inline with the heli and boom.Full forward stick,check pitch on the rear blade.Full back,check the front blade.

Ern, I may be confused about checking the elevators. When I put the blades online with the boom and throw the elevator forward and back, the pitch of the blades doesn't change - the flybar paddles do though. If I give it throttle, I have the same pitch readings I would expect for the actual blade pitch, not the elevator pitch.

[McKrackin]

Hmmm.I'm a bit rusty.

Try checking aleron with the blades inline and elevator with the blades at 90.

[Gabe]

Well bird is down. Belt gear or belt slipped. Piro'd herself right to the ground. Looks like:

Boom
Blades
flybar
Skids
Mainshaft
Maingear
Belt drive gear
Canopy
Canopy poles
Struts
One Align DS520 gear set stripped

Pics to follow.

[Gabe]

[akent]

BUMMER!!!

[dditch66]

Oct 7, 2009 13:07:40 GMT -6 Gabe said:

Ern, I may be confused about checking the elevators. When I put the blades online with the boom and throw the elevator forward and back, the pitch of the blades doesn't change - the flybar paddles do though. If I give it throttle, I have the same pitch readings I would expect for the actual blade pitch, not the elevator pitch.

That's a serious "dirt nap". Ouch.

Where are the flybar paddle labels that cover the cutouts?

Gabe, this is one of the things that confused me on my first helicopter. It almost got me to crash it too when I crossed the elevator and aileron servos cause I was looking at the same thing and not believing the manual (this was before CCPM)

There is something called gyroscopic Precession.
Read this: helicopterflight.net/gyroscopic%20P.htm
Basically, remember that the helicopter follows the swash. The blade changes are offset 90 degrees. The action lags the blade movement by 90 degrees.

As mentioned in the article, if you push right on the cyclic then when the blades are forward/aft, the front blade will go negative pitch and the back blade will go positive pitch. This lift on the blades will not be realized until 90 degrees later when the blades are pointing out the sides. Then you get the left blade going upwards and right blade going downard.

The flybar paddle amplifies the mainblade movement by doing the same thing. It will tilt and then lift 90 degrees later changing the pitch of both blades.

FUNKY! isn't it? But that's how it works.
On a full right roll at full pitch, the rear blade can achieve over 20 degrees of pitch! . (collective pitch value + cyclic pitch addition + flybar pitch addition). That all of course depends on the setup, headspeed, flybar weight blades, etc.

[19000rpm]

Absolutely correctoas usual David! "Gyroscopic Precession". I remember getting into a "discussion" with some guy about that over at RCDisgust.

Happy landings

[akent]

I first heard about that 90 degree magic when I built my first nitro heli 25 years ago. Don't worry, I could never fly or even hover that thing. I am still a newbie, NOW!
That heli still sits over my front door on a shelf as an ugly ornament... It was a Kalt Baron 60. THE worst heli ever designed.

Anyway, I built that thing and thought the designers were horribly screwed up when I was working on the head!! It wasn't until I actually fired it up that I believed!

It is a truly bizarre phenomenon.
Kent

[Gabe]

Oh wow. Didn't know any of that. Very cool.

Well, parts are ordered so I should start the rebuild sometime next week.

[Gabe]

Hey RTF,

Feel free to move the last few posts about the crash to the "Crashes and Rebuilds" section, if you like. I will be documenting this rebuild for everyone to see.

[Gabe]

Hey Kent,

After my latest rebuild on the 500, I was looking at the programing options for the Hobbywing Platinum ESC and I noticed there is a timing option. Do you recommend keeping it at 0 degrees timing like it is for the default, or should I bump it up?

[Gabe]

Scratch that:

www.espritmodel.com/index.asp?PageAction=VIEWPROD&ProdID=8407

I wonder how much more power I will get with this. The default timing on the Hobbywing Platinum 80amp ESC was 15 degrees. I have it set now for 22.5 degrees. Need a test flight.

[akent]

Hi Gabe:
I have played some with the timing and I found that the default 15 degrees was best for me. Lower timing loses power and makes the motor run hotter. Higher timing (22 degrees is as high as I went) did have slightly more power, but it also made the motor run hotter.
So I backed it back down to 15 degrees. It runs awesome there.
It is very interesting though that the website you found shows higher timing!
It will be interesting to hear how that works for you!
Kent