Axe CP separations and setup journal

[markind]

A bit over documented, but extra views may help first-time Belt Modders.

[Edwinssiv]

Awesome Mark! Congrats!
The winds were up yesterday again so only hovering around in the house...but I was at least flying and practising.
Yes the tail, does not respond like the big boys...but it is still much better than the motor driven tail IMHO.
You might try the Hitech HS-50 for the tail...it is a faster servo and still reasonable price...it works great on my Axe. I looked at the LogicTech 3100 but I did not want to spend $54 on it for the Axe.
I had bought a fiberglass canopy for the Axe but had set it aside...so yesterday I fitted, drilled and now have it on :D
I am getting 8 minutes of flight time with my current set up...battery is barely warm...the ESC is barely warm but the motor is very hot....it worries me a little so I may cut back on that.

[markind]

Question:

In image 4937 and 4938 above, you can see that one o-ring dampener sticks out a bit and hence rubs the washer which rubs the blade grip. Are those o-ring supposed to be stuck into the Center Hub and not be visible like this?

I lubed the area with silicon spray so they tend to wanna be slippery and poke out. :confused:

[JEB123]

Did you change the spindle? Did you use one from another heli or something? I have an Axe CP too and i can't get mine to be loose enough to fly the damn thing! When I tighten my spindle (a brand new one), the blade grips get tight and bind up making the fly bar tight too, which makes it hard to fly. I think the spindles ar manufactured too short. I don't think the o-rings should stick out like that though, the washer should be snug against the hub.

[Edwinssiv]

Mark-The O-rings should not be sticking out like that...I had that happen when I did not put the spacers back in between the bearings of the blade grips...

[markind]

Thanks guys - hey it looks like we are on a length of assembly issue. Something is off. But, I'm using the stock Center Hub and Feathering Spindle. So something is not adding up with the bearings and yes I have the stock spacers in between...

So the goal is to have those screws in tight but just have enough play to free up those large washers and still keep the o-rings tucked in... hmmm...

And yes, if your flybar is TIGHT - Do Not Fly! It must be ideally very loose and free-swinging but with no slop. Not easy with mostly plastic parts...

[Ray K.]

YES!

To really drive it home, the dampers must not be exposed. Aside from the obvious vibration problems that this condition will cause, it's going to give you some crazy cyclic and blade tracking problems too. I've never had an issue like you're dealing with here, but one thing that comes to mind is this: are you sure you're using the right washers between the grips and the mainblock? It looks like you are using the metal ones that come stock... so I guess there's no issue there.... There's no way that there should be that much gap, though. There should be very nearly no gap at all... try this:

Are you ABSOLUTELY SURE that the spindle is penetrating all the way through the bearings/spacers/grips? If everything is in there the way it's supposed to be, the ends of the spindle should be very nearly, if not exactly, flush with the outer face of the outer bearing in each grip. Also, check to be sure that your bearing/spacer/bearing set in each grip is fully seated into the recess in the grip. It's hard to tell from your photos, but it appears that they are based on the relative location of the spindle bolt heads. At this point, it's my best guess that your spindle isn't all the way through a bearing.

Every time I've re-built the head on my Axe, I've been able to really reef down on the spindle bolts to their fully-seated position and still have butter-smooth grip rotation. As much as I'm sure you don't want to do it, the best way to check this is going to be to tear the head down and pull all the bearings out of the grips. Then, one by one, test fit each bearing over the spindle and make sure that they all fit cleanly over the spindle, and that none of them are seized up either. One other thing that I've done on my Axe, and I'm not sure that I mentioned it in a previous post, was that I eliminated the spacer and simply installed a third bearing into each grip. I have no idea if it's a good idea or not, but it didn't seem to hurt anything and I feel better knowing that I've got better spindle support in the grips. I figured that this little trick should take some of the strain off of the outer bearing, as there won't be a support gap in between the bearings any more- the spacers have an I.D. that is bigger than the spindle's O.D.

Finally, make sure that your spindle is laser-beam straight. While you've got everything all torn down, take the spindle and roll it across a smooth, flat surface and look and listen for a wobble. This is the litmus test, and any kind of bend in the spindle will be immediately obvious when you do it.

Let us know how you do....

-Ray

[JEB123]

Hey guys, Ray, I did everything you mentioned, spindle is straight too. I reassembled the head using only one damper on each side and the grips turn freely. I looks like the spindle is too short and the washer is pushing against the outside damper causing the grip to bind. I took a caliper to two spindles and got two different measurements! Also, I can see the outer damper sticking out beyond the outer edge of the hub which I don't think is right. This allows the washer to bind against it.

[markind]

YES!

To really drive it home, the dampers must not be exposed.

If everything is in there the way it's supposed to be, the ends of the spindle should be very nearly, if not exactly, flush with the outer face of the outer bearing in each grip.

Let us know how you do....


Jeb: I reassembled the head using only one damper on each side and the grips turn freely.

-Ray


Yes I have used just one o-ring on each side - it works BUT it also should with BOTH in there so that I what I want to get working.

Yes this is a good thing to check. Yep I think there could be a tolerance issue at work here too.

Ok, although I hate it, I will tear down the head again and get everything in there right. I little grinding here and there or slightly thicker washer on the bolt(s) should allow everything to line up.

Now I know what to check for before I put it all back together - thanks all for the tips! I think I can get more bench time tonight.

In other news, yesterday I had 4 awesome TREX flights. The last one was exhilirating - some pretty strong wind - dare I say 20 knots? It was pushing me, and I was worried I would not be able to hear the timer beeping because the wind was roaring in my ears so loud. To get a decent hover, you really got to lean her into the wind - whoa!!

A couple times she popped up and I was staring directly at the bottom of my landing skids. WHHOOP! I spun the tail around for a quick 180 and pulled back elevator and I could level off and be tail-in. This happened twice - the fix was to not take the downwind turn too hard or too fast. It was mighty breezy! :D

[markind]

I got it

Yep - I caved and settle for just one o-ring dampener on each side. Having two means the outside ones poke out and push on the washer, retarding the flybar freedom and thus impairing the cyclic response. :shock:

AH HA!! I did indeed, after 5-re-asseblies of the rotor head and many test-fits, discover that the Feathering Spindle is indeed just a tad too long.

I trimmed it about 1/8" and viola!! When the screws are all the way down (locktite these) the blade grips are close to the Center Hub but those large stock washers have free play (just enough!), and now the flybar is swinging freely and you can't see a space between the blade grips and center hub, and the single o-rings on each side are secured inside the hub and out of sight.

:woot

I held her in my hand and spooled up for some tests. After a minor tracking adjustment, she looks real good on cyclic response and pretty smooth on pull (collective / throttle combined response).

She is now tucked in the Wing Tote right next to my TREX. Just waiting for a calm sunny day... :clappp

[Edwinssiv]

Awesome Mark! The winds came back so I have been hovering in the house again :roll:
With gusts up to 30mph I don't feel comfortable even with my BH let alone the Axe...so hopefully we will be over this soon...the weekend even is suppose to be windy...I am ready for calm weather again.

[JEB123]

Awesome dude! Now I know for sure mine has issues with a spindle that's too SHORT. Too bad I wiped the 3in1 and can't fly it anymore. Anyone have an extra one from a trashed bird you wanna sell?

[Edwinssiv]

I have a brand new one Jeb...If you pay the shiping on it...it's yours. I have no use for it any more because both of my axes are on separate ESC...I eliminated the 3in1...just too much hassle. I touched one wrong and it fried. After that I went separates on them.
I may have a second one I will send along with as well for you...I will check when I get home tonight.
Ed

[JEB123]

Sent you a PM.

[markind]

Awesome dude! Now I know for sure mine has issues with a spindle that's too SHORT.

One possible fix for this is to grind down the bushings that sit between the bearings in the blade grips. (Or find thinner ones - they are out there somewhere...)

Its also possible to shave down the large washers that sit between the grips and center hub. And, you can sand down the flat sides of the blade grips just a bit.

That would all add up to buy you some play between the grips and hub. You just need just enough and that will free up the flybar.

[JEB123]

One possible fix for this is to grind down the bushings that sit between the bearings in the blade grips. (Or find thinner ones - they are out there somewhere...)

Its also possible to shave down the large washers that sit between the grips and center hub. And, you can sand down the flat sides of the blade grips just a bit.

That would all add up to buy you some play between the grips and hub. You just need just enough and that will free up the flybar.

Some very good ideas Markind, I will take note and try. Seems to me the bushings in between the bearings is the way to go, seems like the one fix I would not have to repeat as often. Also thinner washers will add up.:thumbup:

[PilotLight]

Before you start grinding, be sure the bearings and spacer inside the blade grips are "seated" all the way down. I usually install the blade grips then pull on them. They usually slide out just a little extra amount so they don't rub on the center hub.

[markind]

Before you start grinding, be sure the bearings and spacer inside the blade grips are "seated" all the way down. I usually install the blade grips then pull on them. They usually slide out just a little extra amount so they don't rub on the center hub.

Yep that's right. In fact, I had one spindle actually bind on one of the bearings so that it could not go all the way to the screw's washer. This spindle had to be replaced.

On this last job, I test-fit the bearings and all without the blade grips to make sure the end bearings went all the way out.

The spindle can be polished lightly with 800 grit sandpaper to allow for smoother fit of the bearings if they get stuck at some other position.

[JEB123]

That's true, I did have one bearing get stuck while trying to remove it, but the new ones slid across the spidle fine and I still had binding.

[Ray K.]

Yeah, those bearings can be tricky little buggers. One trick I like to use when I'm re-installing them is to use an old mainshaft from an ACP to press them into the grips. It has a flat end and won't damage the bearings, and it's the PERFECT diameter to fit into the grips. When I'm pulling them from the grips, I use the feathering shaft with the bolt and washer still on one end, and pull them out that way. Makes life easier!

I finally got to get out and fly today! That, and my AMA card arrived yesterday, so I'm GOOD TO GO!!!! It was a little windy for my tastes today so I didn't go all the way out to the local flying field, but I did get out for a few test/check flights out behind my apartment. The TRex is flying BEAUTIFULLY, with no changes required other than some gyro gain tweaks. The ACP did okay considering how windy it was. It was so good to get out and finally fly for real! I was so worried about the 'Rex... I did a bunch of mods on it a couple months ago, and was only able to get a brief test flight in before the weather locked me down again. I was a little nervous on the sticks since this is the first time I've flown either bird in many weeks, but it didn't take long to find my groove. That, and NO CRASHES!!!! YAY!!!!!!

-Ray

[markind]

I finally got to get out and fly today! That, and NO CRASHES!!!! YAY!!!!!!
-Ray

A very warm and sunny and surprisingly calm morning came my way today, and I got full wifely clearance to spend the morning at the club field.

I got in 5 excellent runs with the TREX, and an amazing 3 runs with the Son of FrankenAxe!

On the last pre-flight inspection, I found a loose screw in the tail pitch mechanism, so I started with a detailed checkup and found everything fine.

I spooled her up into a hover and checked that the tracking was surprisingly dead-on. Woot! So, I just started inputting the same stick movements I give the TREX...

And she responded pretty close!! Like the TREX after a shot of buorbon and a half a quelude. A little wishy-washy, but quite manageable.

In fact, some circuits looked even smoother than what the TREX would do because the Axe doesn't build up speed as suddenly as the TREX, and the slightly sluggish response resulted in some very smooth and clean turns, both upwind and downwind.

The wind was off and on but pretty mellow, so no problems on landings or takeoffs. Very smooth.

I am just tickled pink with the response of the Belt Mod!! I could hardly tell it from the TREX tail response! Very docile - surprising since I am only using a Gy240 Rate Gyro and cheap S3114 servo in the tail. It required very little flight management - pretty much just point and go. Basically the same stick inputs I give the TREX work fine for the Axe. When I let the rudder stick go to center, she pretty much just kept the heading. EXCELLENT!!! :woohoo

Once I got some confidence, I opened up my pattern and got way up there and way out there!! KEWL!!! :smokin:


Dudes!!! Thanks again for all the support! :hug:

No way coulda got this far withoutcha! :noteworthy


Now then, on to fine tuning:

I noticed when decending into the wind and flaring and decelerating, the main blades (flat bottom plastic trainer blades) would flap terribly, throwing the tracking off by a full inch or so. The flutter would obviously stress the mechanicals, be inefficient, and of course cause loss of lift. :thumbdown:

This condition immediately subsides when I level out and apply a slight bit of throttle. This condition does not exist at any other time - only when decending, flaring, and reducing throttle into the wind - which is common for me when I want to slow down and bring her in closer, or on landing approaches.

After dabbling, I have concluded that the headspeed is too low and have begun incrementally lowering the Normal Pitch Curve and upping the Normal Throttle Curve. I am trying to find the lowest headspeed I can get and not have this problem...

Woot!! I got two good flying birds in the bag now!! :woot:

[Ray K.]

I'd say that you're ready to move on up to fully symmetrical blades on the ACP, then! They seem to do better in headwind conditions like you're describing. Also, I feel like they have a smoother transition into making lift than flat blades, making them easier to fly in some respects. If you're flying clean circuits and your confidence is up (which it clearly is), then I'd go for the syms. How cool is it going to be to fly a loop and maybe a Cuban 8 with an Axe?!?! Can't do that with semi-symmetricals.....

So glad to hear that your belt mod is working properly!

-Ray

[Edwinssiv]

Very nice Mark! :clapppRay...glad you had time to get out and fly!:banana
I flew a couple of packs with my BH yesterday in the morning. I did not fly GSoFA though :oops:.

[markind]

I'd say that you're ready to move on up to fully symmetrical blades on the ACP, then! They seem to do better in headwind conditions like you're describing. Also, I feel like they have a smoother transition into making lift than flat blades, making them easier to fly in some respects. If you're flying clean circuits and your confidence is up (which it clearly is), then I'd go for the syms. How cool is it going to be to fly a loop and maybe a Cuban 8 with an Axe?!?! Can't do that with semi-symmetricals.....

So glad to hear that your belt mod is working properly!

-Ray

Thanks Ray!

Hmm back to those wooden stock blades? I broke 3 sets of them before I switched to the plastic trainers, but that was when the Axe, being driven by my newbie piloting and mechanical skills, was an ultra-CRASH machine. :arggg:

At least, with the plastic blades, you can take a blade strike into some soft lawn and they will not break. Tipping over on concrete could shatter the tips of the wooden blades, but just scuff up the plastics.

But now, I don't think my crash ratio will be very bad at all anymore... So I'll guess I'll cave and get another set of those stock blades... :bomb:

So, the fluttering I was seeing is probably just the limitations of the flat plastic blades. As long as you fly flat and mellow, they are fine. They provide good lift and thus let you run with a lower headspeed, but have this limitation.

My motor was getting pretty warm but not blazing hot after a 5 minute run, and the TP1320 pack still had some life to it, finishing around 11.5 Volts and just a bit warm. So, I guess there is some room to up the headspeed and put in the stock wooden blades.

I thought about using Blade CP blades, but they need modification and that can mess with the CG of the blades. :thinking

Has another source for cheaper symmetrical blades been found? If not, I guess I'll buy the stock ones from my LHS which are about $15, right? It's been a while... :oops:

[Edwinssiv]

$15 is what I pay at my LHS...you could consider CF blades. But they are $40...
I wanted to get out this morning before work and fly the Axe but I just did not have time before work...they have a major wind advisory for this afternoon so I guess I won't be flying this afternoon...Someday these darn winds will let up on us...someday...I hope