500 Tomorrow, it flies.

[Tony]

did you happen to get any of this on video?

IMO, I would take that 401 off the helicopter. piezoelectric gyros are way out dated by todays MEMS gyros. I understand if it's your only one, but you have a lot of money in this bird and I would hate to see a tail issue take it out. at least get the GP790. I know you can buy those brand new for a bill and used for $50 or less if you get the right deal. People are switching over to FBL all the time and selling these.

As for the rubber feet, you are right, they are very grippy (is that a word? lol). And I know the pain you were feeling lol. It's the same on concrete.

YOu may have to bump up that gain to about 80%. I have seen some that need a LOT of gain to hold steady. Remember, raise the gain until you get a tail wag then back it down a few clicks.

Good luck on your next flight.

 

[zenmetsu]

Just waiting for my other gyro to show up in the mail. I grabbed another Quark, and decided to get one over the net vs. locally because Spartan is running a 1/2 off sale that is not honored by the LHS in my area, and then there is the tax issue as well.

Looking at the ESC data, looks like I was hitting 2180RPM. I'm going to bump this up to 2400 for tomorrow's attempt.

 

[Tony]

That's a lot of head speed for a 500. If you hear any cracking, back her down lol.

And no blaming you on the quark. 1/2 off is a bitchin' deal. No matter what it's for.

 

[zenmetsu]

Not really... the manual is calling for 2400RPM hover in normal mode, 2900rpm average in idle-up.

Maybe for a 600 it would be a lot. This motor has a lot of power, so I can probably get it up to 2700 and keep it there even at full pitch... but that is overkill for my current skill level.

 

[Tony]

Ah hell, your right. I'm thinking of a 600. I guess that is what I get for only working on the 600 here lately lmao.

 

[stokke]

Maybe for a 600 it would be a lot.

Nah. My 600 calls for 2400 HS in 3D/SPORT. But 2900 that's a lot - but still sounds abut right on a 500.

 

[Tony]

this is way off topic, but holy crap Stokke! You are already over 700 posts? When the hell did that happen lmao.

And as stated, he is right. I was thinking 600. Just to get back on topic, ya know lmao.

 

[zenmetsu]

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

Thanks for the compliment. I really like teal mixed with orange, and fluorescent orange has pretty awesome visibility against the sky as well as vegetation. In the desert though, a lot of places lack vegetation, but the teal contrasts strongly against most of our desert colors. I was playing around with designs in the Phoenix simulator, and when plopping down ring shaped decals, my fiancé said "those look like eyes"... so they stayed.

 

[Derek]

hmmmm, headspeed, eh? I have the Align Trex 500e...

T-Rex 500E Super Combo KX017014 (Gyro, Servos, Motor, ESC)

This one in specific. How would I get able to tell what kind of headspeed I'm getting and what kind headspeed I should be looking for?

...and those rubber "grippy" (definately a questionable word, lol) things...I took them off....but then after I few flight attempts, I saw a guy at the local hobby shop and he had 600 skids on his 500. I just really liked the "look" of his 500 with the 600 skids, so I did it, too.

 

[Lee]

You can use an App if you have an iPhone or Andriod. Its called Heli Tach. You place the phone near the hell then hover above it and it tells you the RPMs. Or you buy a Castle Creation ESC and it logs all the data for you to down load later.

 

[zenmetsu]

I have the same model, just different electronics.

Some speed controllers will log data during the run, and they know the RPM of the motor. By using your pinion and main gear ratios, the head speed can be calculated. The formula is simply (motor RPM)*(pinion teeth)/(main gear teeth).

In my case, I am running a 12T helical pinion on a 134T main gear. This gets me 0.0896 for my pinion/main ratio. In order to hit 2400RPM for a head speed, I have to divide by this ratio. 2400/0.0896 = 26,786RPM motor speed. In general, you multiply your battery voltage by the kV rating of your motor, 1400 in my case, to get the motor RPM with no load. A 6S pack like I am running will be at around 25V charged, so 25V * 1400kV = 35,000RPM. Under heavy load, however, your battery will drop in voltage to about 3.7V/cell, bringing a 6S pack down to 22.2V. 22.2V * 1400kV = 31,080RPM which is still above the required 26,786RPM to keep a head speed of 2400. Likewise, running 31,080RPM motor speed will get me 2784RPM, and this is about the max that I can expect to have my governor keep up at full blade pitch.

As your pack drops, you will end up around 3.2V/cell, so a 6S will end up around 19.2V. At this level, my motor will likely only keep a head speed of 2400RPM. This is why I am setting my governor to hold 2400 through the whole flight. Later, when I actually learn to fly properly, I'll probably punch it up to 2700 so get better response in the air when doing flips and tic-tocs, at the expense of a shorter flight time and decreased performance as the battery drains.


Now, in your case, you have a 1600kV motor, a 13T pinion, and a 162T main gear. Using the simple math I posted above, at full pack voltage on a 6S, you can expect (1600RPM/V*25V)*(13T/162T) = 3209RPM head speed. This would be your approximate head speed with wide open throttle at zero pitch. In other words, with this gear ratio, you will never exceed 3200RPM. At 12 degree pitch, there is no way in heck that the stock motor will keep the head at this speed, your battery voltage will drop and you will be looking at around 2850RPM if the battery drops to 22.2V with the current load. In theory, you should knock off 10% due to efficiency losses. This will land you at about 2565RPM.

Using an online flight calculator, it states that you'll be pulling 51Amps at 12 degree pitch and you'll end up at 2535RPM head speed, so the number I listed above is pretty close. The battery is calculated to drop to around 20V. By way of comparison, my expected numbers are similar with my gear combination. If I switch to the 162T straight main gear and throw on an 18T pinion, however, I have enough motor to keep the head speed at almost 2900RPM at 12 degrees pitch, but it will be sucking almost 80A from the LiPo.

 

[zenmetsu]

2 pieces of carbon rod + 6 heavy duty zip ties + 4 wiffle balls = super cheap training gear.

 

[zenmetsu]

WooHoo!!! Got her up in the air finally. It wasn't an easy flight though.

The cyclic was a lot more responsive than I had anticipated, but I quickly found out how she behaved and I had no need to dial in any expo on the cyclic or collective for that matter.

The tail though... jesus. I put the gyro gain all the way up to 85% and she just flat out refused to hold the tail. I put it back to 50% (i.e. no gyro), and it only felt a little worse, so I said screw it... I flew without a gyro. I had to hold about 25%-40% right rudder deflection to keep her straight, but other than that, she flew like a champ in the racquetball court. Standing back a good 25 feet, I could seriously feel the air coming off those blades... and man, the sound was unreal indoors, especially with the reverberation.

I didn't put extra foam under the gyro like I had stated that I would... that is in the works right now. But first, I am going to pull the logged data off of my Phoenix ESC and see how many amps she was pulling. The pack was warm, but the motor was pretty hot after hovering for about 2 minutes. I will be mounting a temperature sensor to the motor mount and attaching to my homebrew flight computer to log motor temperature, but this will probably be a few months in the making.

Overall, success... since I brought her back in one piece and didn't have any panic moments. I'll top off my LiPo tonight and fix up the gyro, then give her another go tomorrow morning before I head in to the office.

 

[Tony]

Lets get back to that gyro/tail issue. YOu say you had to hold 25-40% stick? That is a LOT and tells me the tail was setup with the blades folded over and being even. You need a little right rudder with no stick input. The slider should be right in the middle of the tail shaft between the blades and tail block.

 

[zenmetsu]

The tail slider is dead center on the shaft, per instructions.

- - - Updated - - -

Here is a shot with the rudder neutral; pitch slider dead center. Notice, however, that there is no blade pitch. Should be +5 degrees or so, depending upon surface area of the tail blades.




Now, if I set this up mechanically the way that I think it really should be, by having the control arm at a 90º angle to the boom, this is the position of the tail pitch slider and subsequent blade pitch... the pitch here is +4.2º. Notice, however, how far off center the tail pitch slider is.



Either way, under/over-correction should result in rotation and the gyro should be compensating. In fact, a proper gyro should be able to hold the tail regardless of the "center" position, as long as it has full travel left/right.

I'm just going to set it up "incorrectly" according to the manual and have it set as in the second picture. The manual states; "After setting Head Lock mode, correct setting position of tail servo and tail pitch assembly as in photo. If the tail pitch assembly is not in the middle position, please adjust the length of rudder control rod to trim." The diagram (not a photo Align, lol) shows a view from directly behind the boom, so you cannot see the control arm's angle. The pitch slider is shown dead center, but the blades are definitely shown pitched. This is not the case, however, as you can see in my photo.

What *REALLY* needs to happen is the pitch needs to be increased on the blades while keeping the pitch slider where it is. Unfortunately, none of the linkages in the tail can be adjusted. Oh well, guess that I will have a forever gimped helicopter unless I go with aftermarket parts.



BTW, here is a shot showing my awesome training gear.

 

[BOKI]

Good luck on your flight tomorrow! I made my training gear the same way I bought 4 rods just in case i came down to hard at & angle & broke one ! helicopter looks super nice in your photos!

 

[zenmetsu]

In the position on my second photo, the left side of the shaft has 3.97mm of space, but on the right there is 6.11mm. Clearly Align's instructions are flawed, or I have a defective linkage between the tail pitch slider and the blade grips.

When I center the gyro the way I have it now, I have 5.02mm on the left and 5.04mm on the right. FML

- - - Updated - - -

Good luck on your flight tomorrow! I made my training gear the same way I bought 4 rods just in case i came down to hard at & angle & broke one ! helicopter looks super nice in your photos!

These are 1/4 inch carbon fiber rods, I doubt that I will break them. In fact, the helicopter doesn't even touch the ground, as heavy as it is... only the 4 balls are touching. (man, that can be taken out of context, lol)

- - - Updated - - -

OK, I know that I am going to catch some serious hell for this, but who cares.

http://www.helifreak.com/showthread.php?t=204685

I am not alone. Not by a long shot.

My solution will be brutal and simple. I am removing the pitch slider and the attached T-arm since they are loctited and I really do not want to screw with separating them. I will buy a new pitch slider and T-arm, and I am bending the arms out on the T-arm to provide the needed deflection to get the correct pitch with the pitch slider centered.

THEN, I still need to deal with the fact that the control arm is not going to be at a 90 degree angle. This is a more insidious problem, and I may just need to live with it. There are two flaws in the tail assembly. Coming from an industry leader, I find this laughable.

But for tonight, I am just going to set it up as in my second picture. My gyro may be fine with the foam that it has. I will try this first, and then add extra vibration protection as needed.

 

[Tony]

Where do you have the center of your blade grips on the tail shaft? Is there a hole slightly drilled out in the shaft for the grub screw to sit in?

 

[Lee]

+1 move the hub and you'll get blade pitch and centered slider.

 

[zenmetsu]

That thought crossed my mind. The grub screw is directly over the drilled out hole, so it isn't a build fault on my behalf. I *could* grind a flat further in, but ultimately this will result in decreased travel range for the pitch slider. This doesn't address the problem since the rightward travel is terminated by the T-arm coming into contact with the tail rotor hub. Since you are simply moving the tail hub inward, you will consequently need to move the tail pitch slider's "center" position to the left by 1/2 the amount, and in the end nothing is gained other than a decreased travel range. The only fix is to change the pitch without changing the tail rotor hub's position, and you'd have to get longer linkages between the T-arm and the blade grips, or bend the T-arm so that its arms are effectively lengthened.

Anyways, I shortened my control rod so that the control arm is 90 degrees to the boom, like it should be, and I just need to re-adjust my gyro's endpoints so that it will not bind on the left side. Charging my LiPo so that I can have another run here before I call it quits for the night.

As an additional note, the way that they tell you to center the pitch slider in the directions is rather faulty. The reason is that the bearing in the pitch slider protrudes out from the pitch slider by about 1mm. There is a recess in the bearing housing on the tail case that the pitch slider bearing will fit into, and the depth is about 1mm as well. The directions, therefor, should tell you to measure the distance from the tail case to the pitch slider, NOT the pitch slider bearing to the tail case.