Axe CP separations and setup journal

[Ray K.]

Curtis-

That's pretty much exactly what I plan on doing- I'm going to be making sure that my CG is perfect this time. I was a little tail heavy the first time, and little too nose heavy last time. This time, I'm going to make sure it's just right.

I'm really not too worried about the BL tail. I put a tach on the tail with the stock motor, and it appears that the stock motor spins at about 1800-2000 rpm per volt (kV). The new motor is going to spin at 3850 kV, so I can't really see reaction lag being an issue. The new motor also has a peak draw of 4.5A, and the new controller is rated for 8A- again, everything is overkill, so it should work just fine. I do have a concern that the 1:8 reduction in the tail drive will make a little bit of lag noticeable, but there's really only one way to find out.

I'm really not all that keen on maintaining the brushed setup for a couple reasons. First, my Axe has greater rotational inertia in the main drive system than stock. The combination of the higher headspeed and aluminum head parts (which makes the head system heavier= more force required to spin it), along with my stiff swashplate bearing, add up to the motor needing to do more work, which means that the tail will have to work harder to keep all that torque in check. I have a feeling that my main brushless motor contributed largely to the premature failure of my tail motor, because it's very likely that the tail motor was having to work much harder than it was designed and specified to do. Second, the stock brushed tail motors have developed a bad reputation for having a short life span, and longevity is more valuable to me than cheap replacement cost. I'd much rather spend the 60 bones that it took to do the conversion once than spend $30 plus whatever I have to replace because of another motor failure and the inevitable crash that comes with it every 2 months or so. I think of it as an investment.

I may still do the direct drive thing, but I'm going to wait and see how this setup works. It won't be a big deal to take the pinion off of the tail motor and go to a direct setup if I end up not liking it. I may do it anyway, but I'm just trying to get airborne again for now.

I'll let you guys know how it turns out....

Ray

[Ray K.]

Alright, my paranoia and non-stop engineer brain got the better of me again.

Maybe this will shed some light on why I obsess over the details- I'm an Automotive Test Laboratory Technician for a living. It's my job to design, build, and maintain machines. Instrumentation and electronics is a large part of what I do, so RC is naturally a very interesting thing for me. And it's also my job to make sure that what I built works properly- and reliably. This is why helicopters are just about the ultimate hobby for me.

Anyway, I was eating a grilled cheese sandwich and watching "Dirty Jobs" on the tube when it occurred to me- there has got to be a way to make this direct drive idea work. So I went to Tower Hobbies' website and did some searching about. I found two things, and one of them will work. The first, and preferable idea, involves a GWS 1.5mm to 3mm collet adapter. The output shaft of the new tail motor is 1.5mm, but the hole in the props (one set of 2) that I ordered is 4mm. Great. I figure that a layer or two of heat-shrink tubing over the 3mm shaft should shim it up to 4mm. So that's the first plan. Plan B is some other props with a 1mm hole. I figure that if I can't press them onto the output shaft with brute force, I can easily bore out that hole up to 1.5mm to fit the shaft cleanly, and then glue it to the shaft. Both types of prop came in a set of 6, and for about $4 each set. The collet adapter was another $5. So it's a pretty low-cost experiment, and I'm confident that I can get one of the setups to work. I'm going to try both, but my gut tells me that I'll probably end up using the adapter with the large-hole props. Specifically, those props are: GWS 4x4 square propellers (4mm hole), and GWS 3.25x3 scimitar props (1mm hole).

It's going to take some experimentation, but I feel that I should be able to quickly determine the better configuration.

Direct drive just seemed the better way to go. Less parts to fail (no prop shaft, no bearings, no spur gear), and ditching the gear reduction should sharpen up the tail response dramatically- brushless lag or not. This motor is going to spin twice as fast as the stock motor and with no reduction, so relative changes in rotor RPM are going to be way faster than the stock setup. I firmly believe that this is going to work really well.

And here comes the engineer in me again.... if I lose about 6g of weight at the end of the tail, how much is that going to change my overall CG? Good thing my new battery mount system will allow for an adjustable CG!

Until next time.....

Ray

[mashburncs]

I like Mike Rowe too.

[Ray K.]

Okay, guys....

The writeup will be coming very soon, assuming that everything goes well tomorrow. All of the prep work on the fuselage is done, and I also completed all of the prep on the electronics. Both motors are installed, the spur gear, mainshaft, and head assembly are all installed, and all that's left is to install the servos, gyro, ESCs, and Rx. Wire management should be quick this time, because I took the time to actually plan everything out instead of just installing everything and then figuring out where all the wire will go. I expect this to be a very clean setup.

So, the maiden test flight for ACP v3.0 is going to happen tomorrow, and I really hope that all of my planning and design work (THANK YOU CURTIS!!!) comes together as I've been envisioning. It's either going to fly like a dream, like the muscle-chopper that it's built to be, or the tail is going to fail in some spectacular manner and send me back to the drawing board pissed. Either way, I'm going to do the writeup, and I'm expecting to have that complete by Friday.

Wish me luck!

Ray

[Iceman140]

:D :) :shock: :? :lol: :oops: :twisted: :roll: :wink: :glasses2: :mrgreen: :smokin: :noteworthy :WOW :lolol

The gang's all here and we'll be waitin'.

Ed

[alucard]

Hello there I am from Puerto Rico and I love all your writing and all the update that you people did to your axe cp. The fact is that here in the island evrey body loves gas heli and when you ask some question of how to update the heli they say move up to a Raptor 30. Well I been flying my axe cp for about 5 moths all stock and I am geting pretty good of it, of course aster mmmm to many crash and a lot of practice in the simulator. Well anyway I just hook up the c 12 ESC for the tail Gyro but I installed the Alingn RCE 500x Gyro and all the wiring and connection's went pretty well. but I can get the tail where is supose to be the best setting is still some wang present it keep the tail in place but with some wang. My question is is really because the Gyro is not that good and I need the Futaba GY 240 or what. Evrithing else is stock. Ok guy thanks for all your help :arggg:

[alucard]

Hello there I just love all your writing about the update of your heli well I am from Puerto Rico here most of the pilot fly gas heli and if you ask them something they just dont know and if you go to the hobby shop they said move up to a raptor 30. Well I been flying my axe cp for about 5 month and i geting very good, I just hook up the gyro for the tail but I use a Aling Rce 500x and I can get the tail where is supose to be. I dont know is beacuse the Gyro and I rally need the Futaba 240. I olso hok up the C12 ESC. My question is Did I need the futaba Gyro or is supose to work with the Aling one and If you guy recommended to change the stock 3-1 Thanks for all :lol:

[Iceman140]

alucard,

look at the Futaba G190 gyro for the Axe if you need to save money. It's only $60.00 and unless you're going to enter competition, should be enough gyro for flying a lightweight heli. GY240 or 401 is nice though. I'll probably go with the G190 when I do my separations and remove the 3 in 1.

Have Fun and Keep flying.

Ed :glasses2:

[Ray K.]

IT FLIES!!!!!

I really wish I could comment on how well the new tail setup works, but I'm ashamed to admit that I forgot to make sure that my DX7 had a full charge on it. D'OH!

I can tell you this, though: In the roughly 2 minutes of hovering that I got in before my radio threatened to quit on me, I experienced no major problems. I wagged the tail a little bit, and it appears that the tail control is MUCH sharper than it was. I didn't have enough time to get the gyro gain tweaked in, but at 75% gain there was no wag, and response was crisp. I really wish I could say more, but I didn't want to risk crashing again after I just rebuilt the bird because of a dead Tx. That, and it was a test flight, so I didn't even try to hover it more than just a few inches off the ground. But in the brief run that I did get, it would appear that this project has been a success.

The tail motor seemed like it was a little hot for such a short run. I know that BL motors run warmer than brushed motors, so I'm not sure if I should be alarmed or not. If I feel that it's getting too hot, I'm going to try some tail rotor props that are either larger diameter or have more aggressive pitch, in hopes that I can get the tail motor to spin a little slower. It may prove to be no big deal though, so I'll just have to wait until I have a chance to do a proper set of shakedown flights tomorrow.

I really hate having to wait because I made a careless mistake!

I'm probably going to re-engineer my battery mount system too. To put it simply, it sucks. It doesn't hold the battery as securely as I would like, and it's a ***** to remove the battery- double whammy. I have a couple ideas, but I haven't determined exactly what I'm going to do. The other problem is that I'm a wee bit tail heavy, and I'm unsure as to how I'm going to solve that too. If I'm really slick, I'll figure out how to position the battery such that it solves my tail-heavy condition.... time for the old thinking cap. I'm also considering shortening my tail boom to fix the problem, but I see that as a less than ideal option. I'd like to retain superior tail authority.


alucard-

I can't see why the Align gyro shouldn't work. If you've tried adjusting the gyro gain up and down, and you're still not getting satisfactory results, get a different gyro. Just be sure that the one you have really won't work before you do that, though. Adjust the gain to about 30%, and your tail should badly drift. Then adjust your gain to 100%, and your tail should wag really badly. If that's how it happens, then your gyro is fine- you just have to find the right setting. It will very likely be in the 50% to 70% range. If that doesn't work, then Ed had it right- take a look at the Futaba G190 and the E-Flite G90 as options for a replacement. Both are inexpensive, and are known to work well in this type of application. If you're willing to spend a little more money and you really want a heading hold gyro, I recommend the Futaba GY240. Mine works very well, and I like it very much.

Well, that's enough for now, and I'll be posting again tomorrow with full test results. Assuming that I don't do something stupid... again.

-Ray

[Iceman140]

Great Job Ray!!!!!!

Only one thing to say on the Tx Charging thing. :arggg: Can't engineer out the human factor.

I thought I saw a link from you or someone about a site selling CNC head assemblies that are better if not cheaper than Helimaxx. Any idea where that website is?

Finally got my Axe flying OK. Six feet up and six feet down and short flight with no significant damage. Bloke one grip, but I had to. I had 7 in my inventory and I really hate odd numbers. Modified my Verticle fin with a double looped wire thingy for support and it works well. Looks and acts like a kangaroo foot and really protects the tail rotor blades.

Keeping 'em flying. Talk more later.

Ed

[Ray K.]

That's good idea with the wire loop!

I think that those CNC had pieces were at MicroHeli.om. They had a swashplate and blade grips for ACP. I can't say if they're better or not, but they're certainly cheaper. I stayed away from the aluminum grips though, because I still crash frequently enough that I don't want to spend the money on blade grips that I'm going to ruin. Besides, the plastic ones make for an engineered weak spot in the head, and I pretty reliably break only the grip(s), which are cheap and relatively easy to replace.

-Ray

[Iceman140]

Great! I'll check that site for CNC parts. Here's a pic of the wire loop thingy. I had to make it fast because I had to fly. I made a verticle fin that extended down as far as the loop, but I didn't have the right hardware to install it. So when you just gotta fly, improvise. :mrgreen:

[alucard]

Hey thanks for all your help well today I waqs kind of busy but the best setting is in 45 to 50% of gain but it still some wag on steady hover when you pitch up with idle up it lock in place but in hover it wag like a demon it move about 5 inches from center to the right it look like is not have the sufficient torque. I will try a couple settings more with a full battery.
Thanks again

[Ray K.]

Again with the mixed results.... allow me to elaborate.

I'm a little hesitant to say beyond doubt that my tail is a good setup. At this point, I don't trust it yet, but the last 3 flights that I took with it did indeed go very very well. The tail control is noticeably crisper than stock, and it feels a bit more locked in too. But this is what happened:

My first setup was with the larger GWS 4x4 prop, using a collet adapter to mount it to the motor output shaft, and the prop was on the same side of the tail as the stock setup. I was forced to have it rotate in the opposite direction as stock, because they are scimitar style props and can only really work spinning in their design direction. Not a big deal though. What was a big deal was the fact that the motor just gave up on me mid-flight- good thing I was in a really low hover! I let the heli sit for a moment, and tried again. The motor began to work again, but quickly died again. So, figuring that it was getting too hot and the ESC was shutting down as a result, I decided to flip the motor mount over, flip the prop, and reverse the tail motor direction so that the thrust from the tail prop would be blowing over the motor and heat sink, improving cooling. Boy, was I wrong! The motor lasted maybe 2 minutes before it shut down. So I got pissed off, went to go have a cigarette, and halfway through my smoky treat I remembered that I had the smaller GWS 3.25x3 props with me (I usually fly at work- my tools are there, I have an electronics lab available, and I have plenty of room to fly). So then I thought about why the motor could be shutting down and getting so hot... I thought that maybe I could be putting too much load on the motor and ESC with the 4" prop, so I decided to give the smaller prop a try and see if that changed anything. At first, it seemed to be working okay, but after about 5 minutes it shut down again. So I got mad again and had another smoke. Then, I realized that the tail fin was blocking about 1/2 of the thrust path of that prop. So I moved the fin forward on the tailboom enough to give the prop totally unblocked flow. I set her up with a fresh battery, and gave it one final go before I gave up. I'm glad I did, because that combination worked, and it's the one I intend to stick with.

The first battery pack with this combination was just a super-low hover, and I didn't even try to do anything fancy. I deleted the battery warning system on this rebuild, and I wasn't sure what kind of flight duration I was going to get, so I set the countdown timer on my DX7 for 6 minutes- just to be safe. Everything went well, and there was no tail motor drama. When I put the battery back on the charger after that flight, I still had 3.9v per cell left, so I was in great shape. Next flight, I set the timer for 8 minutes, and got a little braver with the maneuvering. The tail performed very well... piros were smooth and predictable, and the tail stopped right where I put it, right hand and left hand. Then I tried some rapid tail direction changes, and that went well too- no overshoot, and no lag either. I still didn't trust it enough to hover more than about a foot up, though. After my 8 minutes was up, the tail was still live and well, and I had about 3.7v per cell on the LiPo- so far, so good! For the last test flight of the night, I set the timer for 10 minutes. I didn't go all out, but I did do some sideways, forward, and backward flight- the tail held fine through all of it. Satisfied with that, I finally felt comfortable taking my hover up to 12 or 15 feet. I didn't do any really high-power climbouts or rapid descents, but I wasn't a wimp about it either. The tail stayed solid with the moderate pitch/throttle changes that I threw at it, and I think that it'll do fine with more aggressive pitch changes. After 10 minutes, I had 3.5v per cell, so I think that I'm going to set my timer for 11 minutes and leave it there.

I still have yet to do some pirouetting climbouts to really tax the tail and see what it can do. I still need to get the gyro gain dialed in too- I'm at about 70% gain, and it doesn't wag yet, so I'm going to try a little more and see if I can't get this tail really really tight. My only remaining concern about this setup is that the prop is thrusting in the direction that it's possible that it could pull itself off of the motor shaft- it's only pressed on (1.5mm shaft in a 1mm hole). Granted, it's pretty tight, but I'm also pretty paranoid, so we'll see. I may put a dab of CA on there for peace of mind.

I mentioned in an earlier post that I was a little tail heavy. Well, between the smaller prop, ditching the collet adapter, and sliding the tail fin a little forward, my CG just happened to come out perfect. Happy day! And my battery mount turned out to be alright after all- I was just using too much velcro. It'll make more sense when I do the full "how to" writeup.

So for now, it looks like the BLDD tail is a success- even though I had to fight with it a little and very nearly completely gave up on the idea.

Now I need to come up with another project. I have a fully separated and hot-rodded ACP now! I should probably focus more on my piloting skills so I can really enjoy this bird now....

Until next time....

Ray

[Iceman140]

Hey Ray,

Sounds like you're having fun. I guess we can finally cross the RTF off the box. :)

I lost a skid support screw and replaced it with a tie-wrap. I was so proud of myself, especially when NASA called. Seems they were only looking to see if I had your phone #. I can't wait to see what you can do with a TRex 600.

Keep up the good work. We'll be waitin' for the final notes on the six million dollar Axe. :mrgreen:

Keep em' flying buddy. :fly

Ed

[alucard]

Hello there well finally the set of the tail is there is about 40% with 3 click to the right in the trim and the tail is working now. I must said that here in Puerto Rico the wind went like hell I did all these setting with wind over 5 mph so when the tail wag is because it try to lock. But today morning there was no wind and I was able to confirm that at 40% is just wright and I did. I hover up at 20 feet go down fast and but pitch up and the tail stay lock. With the stock Gyro that will be impossible. Whell thanks all for your help. And planing now to replace the 3-1 any suggestion? :idea:

[Ray K.]

alucard-

Replacing your 3-in-1 is easy- you're already 2/3 of the way there! The 3 functions of the 3-in-1 are: main motor speed control, tail motor speed control, and a rate gyro. Since you already have the tail separated, all you need now is a main ESC. If you're going to stick with the stock main motor, just get something like an Electrifly 25A brushed motor controller, wire it up, and be on your way! It will plug into your receiver in the same place that the 3-in-1 did. If you want to go brushless, you'll need a new motor and a brushless controller instead of a brushed controller. I'm using an E-Flite Park 370 motor and a Castle Creations Thunderbird 18 controller, and it works very well. If you have any more questions, feel free to ask!

Ed-

TRex 600?!?! It's gonna be a while before I get that far! I've only been doing this since April, and I promised myself that I would fly the Axe for a year before I got another helicopter. Resisting the temptation to be late on rent and go get a Mini Titan or a TRex 450SA is getting pretty tough though.... Besides, I've got my hands full with the Axe for now. At this point, my only plans are to get really good at flying it, and do the swash link ball link conversion. Maybe I'll get some carbon blades later this summer- if I can stop crashing every 20 flights or so! The main goal of all my mods was to reduce the likelihood of mechanical failures, but like you said- you can't engineer out the human factor! So that's my next project. And I agree with you about the zip-ties.... they're almost as useful as duct tape! I think I've used several hundred of them throughout all of my rebuilds and repairs!

-Ray

[Iceman140]

Ray-

Thanks again for all the info. I'm still debating whether to go with the separations, around $120.00, or keep flying this bumble bee of a heli stock until I'm ready for larger. I suppose if separations will give me a more stable flight to learn from, it would be the way to go. It's still hard to remember you're playing with a simple RTF Axe CP. I wonder what it would cost if it flew with separates RTF. I think it's time for RAYK Enterprises. You design 'em. We'll build 'em to specs, and we all get rich. Sound good?

Anyways, keep up the much appreciated research and, "FLY ON GENTLEMEN".
Have a good weekend.

Ed :fly

[Ray K.]

....we'll call 'em the RAY-K-47!!!!

In hindsight it probably would have been cheaper, or at least cost the same, to have just bought a "better" heli to start with. But that's not how I roll. I'm also a car guy, and I can't remember the last time that I thought stock was good enough. I can't seem to resist the urge to tinker and modify things, and my helicopter proved to be another one of my famous never-ending projects. If you were to stick with the stock radio and really shop around for the best deal on your parts, you could probably do the whole thing for about $300. Add in the cost of the original heli, and you're right about on the mark for something like a TRex 450. Except now, you have a really expensive, tiny, two-motor helicopter that will never really handle wind very well, and may never do really hard-core 3D. But you will have the satisfaction of having a really really good Axe CP.

I don't regret doing what I did, and I'm sure that I won't outgrow this heli in the year that I'm making myself wait to get a proper variable-pitch tail 450-class helicopter, so I think it works out fine. After that year, the cost of this build will be so spread out that it'll be worth it. It's just a big investment up front.

1 Axe CP RTF- $200
1 DX7 w/ AR6100- $310
3 Hitech HS55s- $45
1 Futaba GY240- $110
1 E-Flite Park 370- $50
1 CC Thunderbird 18- $35
1 Electrifly Ammo 12-30-3850- $25
1 GP SS-8 ESC- $25
6 GWS 3.25x3 props- $4
2 Electrifly 3S 15C 1250 LiPos- $70
Aluminum head- $120
Assorted building materials- $100
------------
$1094

OOOOOOWWWWWWWWWWWIIIIIIIIEEEEEEEEEE!!!!!!!!!!

Don't forget to add all of the replacement parts, the battery charger, and the many many hours spent building, repairing, test-fitting, and doing research.

Maybe I should have got some new tires for my new Civic Si instead...

-Ray

[alucard]

Hello Ray well There is a few question the 25 a ESC need any adjustmen or is just plug and play and if you get any more head speed or the head speed is adjustable and how you do it Thanks for all your help it is great
alucard :wink:

[Ray K.]

alucard-

There will be some minor setup to do on the ESC, but I'm sure that the instructions that come with it will make it simple. I don't actually have this ESC, but I have bought several other Electrifly products, and the instructions are always very good and really easy to understand. The headspeed is going to be exactly the same as with the stock 3-in-1. The only way to adjust your headpeed is to get a motor that spins faster than the stock motor, change the pinion gear on the motor (more teeth on the pinion makes for higher headspeed), or both. If you had a programmable radio, you could make changes to your heaspeed that way too, by adjusting your throttle curve. However, that will still not change the maximum headspeed available- you need a new motor and/or pinion to do that. Personally, I wouldn't worry about having a higher headspeed until I was doing some pretty aggressive stunts. The stock motor and it's headspeed should be just fine while you're still learning to fly. If you're really dead-set on a higher headpeed, the simplest thing you could do is buy a pulling tool to remove the stock pinion, and then install a pinion with 2 or 3 more teeth.

The way you calculate your headspeed is like this:

(Input volts x Kv) / gear ratio

Kv is the amount of RPM per volt that the motor will make.

For example, on my helicopter, I have a 4100 Kv motor with a 10 tooth pinion. The spur gear has 180 teeth. So my gear reduction is 18:1, and my battery has a nominal voltage of 11.1v. 4100 x 11.1 = 45510. 45510 / 18 = 2528.3 RPM. This headspeed has been working great so far, but I may end up going to a 12 tooth pinion, giving me a headspeed of 3034 RPM. As you can see, a very small change on the pinion makes a large difference in headspeed.

Hope this was helpful!

-Ray

[Gandalf_Sr]

Good Luck Ray. I too have a BL Axe that has a weak stock tail motor which may have contributed to my major crash. I'm well on the way to the rebuild but I think I'll follow your example so eagerly waiting to see how things go for you. BTW, I'm in A2 Michigan.

[Ray K.]

Gandalf-

It depends on how brave you are, but at this point I feel comfortable giving you the thumbs up to do it. I flew it a couple more times today, and had no more problems. I only had the chance to fly twice today, because it was really windy here and the wind didn't calm down until dusk. I only had enough daylight for a couple flights. But like I said, those went well, and with 5 flights and no emergencies, I'm confident that this setup works. I had the opportunity to do those piro climbouts, and the tail performed acceptably. Seeing as a piro-climb is a somewhat unusual maneuver, I didn't feel too bad when the piro rate suffered a little. The fact that it was still able to overwhelm the main rotor inertia at all was good enough for me!

I might try some different props though. I was reading through my back issues of RC Heli magazine, and found an article about a Blade CP Pro that's using a direct drive tail- the props that that guy was using are GWS 3x2 squares, and I think I'd like to give those a go and see how they do, if only for comparison purposes. They're dirt cheap.

I'm going to try to do that writeup sometime this weekend, so keep a lookout! I still have some photos to take, but that shouldn't take long.

-Ray

[Iceman140]

Hey guys,

On a lighter note, I think I may have found the reason for our unexplained crashes.
Check out this article I found from a recent FBI study on remote control.




Ed :glasses2:

[alucard]

Hello guy well thanks for the information on ESC. The reason that I ask of the speed of the motor is because a read in some heli magazine that some ESC are programmable and some use a computer link to program that is cool. Well another thing now Radio I was doing some research on radio and I planing to move up with a programmable radio. I plan to stay in heli and most probably on electric I wonder if a Radio like the one I like the Futaba T 6EX is good investment for the future and if you have like 3 heli you always need to buy a futaba receiver to work with this radio. This radio is a spektrum so I can lose when radio receiver compatibility. Thanks hey The cp fly super nice finally some calm day make my fly very pro even dough I am a rookie. Well thanks Again Ray :noteworthy