500 Tomorrow, it flies.

[zenmetsu]

My T-Rex 500 is complete. I picked up the servos this morning and finished installing everything this afternoon. I added a CC BEC-Pro just for peace of mind.



The wires are all routed neatly. The power lead to the BEC here is well clear of the motor, though it is hard to tell from this photo. Positive lead from the battery is on the left of the heli, and the ground connection is on the right. I leave the ground plugged in and the positive lead disconnected until I am ready to go.



Here you can see the positive terminal that is connected to the ESC and the BEC via the Deans connector. I put the male connector on the BEC so that the battery cannot get shorted if the BEC is disconnected for some reason.



The other side. The spare connector hanging near the motor wires is for the ESC's throttle connection to the RX. This is a servo extension cable with the positive lead removed. I decided to allow for a disconnect here so that I could easily program the ESC by disconnecting the receiver here.

The wires are well clear of the main gear, but the photo doesn't make this apparent.



The rat's nest. The heavy gauge red/black pair runs down to the BEC. I am utilizing the Bind/Data port to power the receiver and servos. The second connector from the BEC is plugged into the gear channel of the RX. I added the data line for the gyro gain to the connector for the BEC.



All ready for the maiden. Swash plate leveled, all servos properly adjusted for direction and travel. Gyro direction verified correct. Had to reverse pitch in swash mix, everything was working with cyclic control, but collective was backwards. Oops.

I spun her up just to check for vibration and and tracking, and she was pretty steady on the ground. Tracking was also spot on to my amazement. There is a noticeable popping sound when I add cyclic, and I assume that this is an interaction between tip vortices in the main and tail rotors; fun stuff, my 250 never did that!

 

[Tony]

popping sound? Maybe my definition is different from what you are actually hearing. but to me, popping when you add collective means there is play in the main shaft or elsewhere. Can't wait to see this thing in the air!

 

[zenmetsu]

No, this is definitely air, kinda a thud more than a pop. Initially I had my normal pitch curve set linear, so it was spooling up at negative pitch. As soon as I put it back to my usual 50-47.5-50-75-100 pitch curve, the sound went away unless I spooled it up, hit throttle hold, and punched the collective.

Granted, this was all in my living room so I was definitely playing with fire. Couldn't take her outside because it is STILL raining. Seriously considering going down to the racquetball court. No one should be there at 4am.

 

[Tony]

What the hell man, you are getting way too much rain for being in Phoenix lmao.

and I know the sound you are saying now. Yeah, just wait until you do a pitch pump outside. Teh sound of those blades is unlike no other. Love it.

 

[Lee]

Wow you have really gone to town on the electronics. CC Pro BEC & a CC 100A ESC. Thats what i have running on my 8S 600. On my 500 i had 60A ESC with CC 10A BEC. Good luck with the maiden.

 

[zenmetsu]

Not much weight difference between 100A and 60A. I figure I can look at the logs after I start doing some 3D stuff and see if I can get away with a smaller ESC. This is a very power hungry motor though, people who have run it say that it is a beast as long as it has a decent battery to suck dry. The last thing I want is for an ESC to shut down on me in flight.

 

[Tony]

Then you get a great chance to learn how to do an auto lol.

 

[Derek]

ooooo yeah!!! I love the sound of the blades on my 500 doing pitch pumps. Its just "UNREAL!!!" I'm still very much a novice when it comes to my 500, but I can do pitch pumps. What a sound!!!!

 

[Tony]

First time I did one on a 500, I just about pissed myself lmao. It's on video too. First it's there, then it's GONE lmao. I miss that helicopter even if it was totally a clone. Ah well, there will be another. I'm having a blast with the RCH Heli. But I know I will want an electric again at some point.

 

[zenmetsu]

You think a 500 is crazy, try pitch pumping a 250 running at 5K rpm head speed. First time I did it, the heli shot straight up like a freaking rocket. I was not in idle up, so I immediately dropped the collective to zero, but there was so much momentum that the helicopter just kept going up for a few seconds. Then the helicopter started to flip over to the right, and I remember I was tried to correct with the cyclic, but I didn't have enough head speed. I raised the collective up about half, enough to try to keep the 250 spinning side up but low enough to let it come back down to a comfortable height. Closest I probably ever came to losing the helicopter completely, and all because I over reacted with the collective.

We'll see how the 500 compares. The thing is heavy, and the thought of these things doing high speed 3D just blows my mind. Those blades must generate tremendous force considering the fact that the helicopters appear to fly with no regard to inertia.

 

[Tony]

Dude, I assure you the 250 has nothing on this 500. Just you wait bro. You will have a perma-grin after your first flight!

 

[Adam]

That bird looks great man. excellent job on the wiring.

 

[breeze400]

I've got to admit you did a first class job there! I like the fact that everything looks so neat. All the wire looms and all great job on the assembly! Now get some video in the air! Lol

 

[murankar]

Looks great, nice custom paint job. Now you know for sure that your canopy is a one of a kind.

 

[zenmetsu]

How did the maiden go?



It didn't. On the plus side, the creosote by my front door is super green now (the bush on the left) and is making the whole house smell good, if you like that kind of scent.

I guess I caused this rain. Just like washing your car or buying a good telescope, finishing a helicopter guarantees poo-poo weather for a week.

 

[stokke]

That's a clean wiring job! Good luck with the maiden

 

[zenmetsu]

22:45 and it is *STILL* raining. WTF mother nature, go home, you drunk.

Anyways, I cannot take this anymore. I'm walking my sorry butt down to the racquetball room with my helicopter... I'll only be able to do a little hovering and stuff, but at least I'll know that everything is set up correctly. At least if it blows up, I'll be able to easily collect all the pieces.

 

[Tony]

Hope all goes well. Closed spaces and a 500 can be a bad combo lmao. Let us know.

 

[zenmetsu]

The racquetball room is pretty big.

Well I tried, and I just couldn't pull it off.

First issue, despite the fact that I double and triple checked everything, my swash mix was backwards on aileron. I almost had "an incident", but I dropped collective in time. I went to adjust the swash mix, and my last changes did not get saved... wtf?! Oh well, I fixed, shut off the transmitter, brought it back online and everything was happy, the settings were saved.

Second issue, gyro didn't seem to be holding properly. Gyro direction is correct, but it just doesn't seem to be giving enough input to correct motion; when doing the finger push test, the direction was ok but it seemed to take way too much movement before I saw blade response. Secondly, there may be vibration issues, and I only have a single foam pad under it. I will try putting the foam+metal pad+foam setup from my Quark under the GY401 to see if it helps out. I bumped the gain all the way up to 68% and it still seemed to require way too much human input to keep the tail straight... and this is all while still on the ground and spooling up.

Third issue, the rubber skid retainers are VERY grippy on smooth floors. I was very nervous as the helicopter was getting light on the skid; all I kept thinking was 'dynamic rollover... dynamic rollover...' and I just couldn't bring myself to bring the collective up to takeoff levels.


Now as for the correction to these issues, I will improvise a training gear for this so that I can get a little more comfort and confidence in the take off, at least until I know that the 500 is set up correctly and I learn the flight characteristics. I will put better vibration protection on the gyro tomorrow morning. I will also pull down the ESC data and look to see what head speed I was getting at 80% throttle. It is entirely possible that I just need to go balls to the wall and run her at a flat 93% throttle and give the gyro more tail authority to play with. I will set up a 0-47-93-93-93 throttle curve on it for tomorrow's flight.

 

[BOKI]

zenmetsu; Just want to say good luck tomorrow flying & your helicopter looks great! Looks like a really nice build! Thanks for the pictures!