Roban AH-1W Cobra 700 Size Scale Helicopter

[PawPaw]

I really like this RC Logger so far. It displays pitch & roll at the same time & is easy to calibrate & zero. It’s shortcoming is the swash plate adapter & I discovered that’s what was kicking my butt. It’s robust & solid but not a really good fit on the AH-1W swash plate allowing a mm or two slop on the bottom. Easy to fix with a piece of aluminum tape but a proper solution would be to Dremel more clearance around the swash plate shaft bearing on the adapter plate. My original head settings were spot on to begin with but I changed everything in the Demon FBL before I discovered the adapter issue. It’s all reset to normal & time to switch gears to another challenge.

[PawPaw]

To revisit an earlier post, I’m still trying to figure out this part of the Demon 3X FBL programming. When main is set to 0 pitch at 50%, Demon is wanting a “2 ball length” positive link adjustment, which I’ve done. I haven’t measured it yet, but 2 turns on the rod looks like a lot of positive pitch. I’m inclined to reset the tail to 0 to match the main, but thinking this FBL needs that mechanical offset for the gyro? Just seems like that much more travel to 0 & negative with a fixed positive dialed in but Demon’s wanting it. Opinions?

[sfcfury]

To revisit an earlier post, I’m still trying to figure out this part of the Demon 3X FBL programming. When main is set to 0 pitch at 50%, Demon is wanting a “2 ball length” positive link adjustment, which I’ve done. I haven’t measured it yet, but 2 turns on the rod looks like a lot of positive pitch. I’m inclined to reset the tail to 0 to match the main, but thinking this FBL needs that mechanical offset for the gyro? Just seems like that much more travel to 0 & negative with a fixed positive dialed in but Demon’s wanting it. Opinions?

PPaw... I'm sorry I can't offer much input... just haven't dealt with the demon. Perhaps its just them loading in some pre compensation? B/c following the directions, cobra is a CCW rotor, so you would give two ball link rotations to left. Are you working on a test bed? Worse case is give it a hover test, if you don't like it, go two ball links back right.

[DCORSAIR]

Sorry I can't help you out either, not familiar with the Demon FBL gyro, I just got into FBL and the Microbeast is my first gyro I have ever tried to set up, I don't see it in my instructions but I did add in a little left pitch as well and it seems to be perfect, I have no trouble lifting off nice and straight, I think they want you to put that left pitch in there, like sfcfury is saying, can you post a pic of how much pitch they are asking for and maybe we can see, here is my AH-6 tail rotor with the left pitch for take off, also where my pitch slider is.

[PawPaw]

Thanks, guys....Yes, I just got it mounted to the test bed (copied yours sfcfury, of course) and will get it outside when the rain quits. I read good reviews of the Demon so don’t question it overall just think the “two ball length” instruction to be kinda vague. I see the benefit of a little offsetting tail pitch & will keep it set. I’ll measure it & send a pic later after wife frees me up a minute.

[PawPaw]

Sorry for pic quality but maybe good enough to see....gauge shows 8.9* but didn’t have a target value to shoot for so that’s what 2 full turns on the link rod ends up being. Really doesn’t look as extreme as I first thought when comparing to DCCORSAIR’s pic so gonna call it good. Thanks again!

[DCORSAIR]

That does look a bit much for a two blade, my pic is my 4 blade tail rotor, my camera angle makes it look like I have more than it is, now my Magnum PI has the 2 blade and I will get a pic of that today and see the difference, got to thinking about your Demon instructions, maybe on certain helis they don't have the thrust angle built into the pitch slider and want you to offset the tail rotor yourself, yours should have the built in pitch needed when the pitch slider is lined up with the tail rotor shaft, not sure now that I see how much they are asking, I guess you will find out soon, just becareful when you first get it up to speed I guess, I also do something a little different than most guys do, I do my first spool ups on a piece of plywood using zero pitch on the main blades and a linear throttle curve which is a little less headspeed than normal flight so I can't get an accidental lift off, then I monitor the tail and see what is it going to do, so basically I turn everything on and let my gyro initialize and do not input any tail movement, spool it up and focus on the tail, the plywood will let it spin if things are way out of adjustment, I still don't touch the tail input and make your adjustment until you get it close, this is only if you get a bad spin or something like that, if your confident that everthing is good, then skip all my jabber, lol. This is my way of doing the first hover and flight setups and it will not work for everyone I understand that but just wanted to share a couple of things, of course blade tracking is a must do as well at the same time your watching the tail and getting it right.

[sfcfury]

I don't think I've ever put a pitch gauge on my tail ... Looks good... When it comes time to test it, if it feels like too much, maybe just back one turn out... But something tells me that it will be okay!

[sfcfury]

I guess what kinda making me scratch my head in the first place is that, if you're heading lock mode, the tail should adjust to wherever it needs to hold the nose steady anyways... so where it starts seems irrelevant, unless of course it's staying pegged one direction or the other to maintain a straight nose.

[sfcfury]

*Although I know heli rudder 101 says you should have some loaded in for rate mode... Just wanna throw that out there lol... I just never fly in rate mode...

[DCORSAIR]

*Although I know heli rudder 101 says you should have some loaded in for rate mode... Just wanna throw that out there lol... I just never fly in rate mode...

Yes your right about that, I used to be a rate mode flyer, didn't like headiing hold, now I only fly in HH mode, but its when your gyro first initializes, its good to have it set with the proper tail pitch, makes scale take offs look nice, I hate when I see a scale heli go left or right all of a sudden on lift off and the poor pilots nerves are shot already because he has thousands of dollars into it, lol. If you have the tail pitch set right from the start and not rely on HH mode to straghten it out, it just makes it so much smoother transitioning into a hover, just the way I do it, we all have our quirks......

[PawPaw]

Well, looking at my pics again I see one of them makes it look like more pitch than it really is. The blade end view is the best one. Glad I brought this up because I’ve now learned I set the tail up wrong to begin with. I set the tail pitch to zero to match the main & didn’t pay attention at all to the slider position so wouldn’t know if Roban builds in offset pitch or not. It’s on the test stand & ready but my yard could breed ducks right now so good time to start over on the tail. Thanks for the info, y’all!

[PawPaw]

Now it’s right...took out the “2 ball lengths” Demon wanted & can see the offset Roban built in.

[PawPaw]

Got an off topic question for Spektrum gurus: I’m a Futaba guy but do own a DX6e transmitter new in the box. Couple years ago I bought an electric Pitts BNF that has an AR626a receiver installed...never flew it. I’ve read this 626a is locked into AS3X but can be reprogrammed? Book says I can bind without SAFE so not worried about that too much. I ordered a RotorScale 450 Huey & Microbeast FBL yesterday so thinking I’ll try this Spektrum system in it. I will order a different receiver if I need to but would like your opinions on the 626a since I have it on hand? Thanks!

[sfcfury]

Got an off topic question for Spektrum gurus: I’m a Futaba guy but do own a DX6e transmitter new in the box. Couple years ago I bought an electric Pitts BNF that has an AR626a receiver installed...never flew it. I’ve read this 626a is locked into AS3X but can be reprogrammed? Book says I can bind without SAFE so not worried about that too much. I ordered a RotorScale 450 Huey & Microbeast FBL yesterday so thinking I’ll try this Spektrum system in it. I will order a different receiver if I need to but would like your opinions on the 626a since I have it on hand? Thanks!

Good morning! First literally I'm not much of guru in the RC world lol... literally armed with just enough knowledge to be dangerous!!! Just by chance, everything I have picked up has ended up being a spektrum product for the most part. I think my trex 500 flybar kit (that I used for my cobra 500) came with the Align GP750, then I switched to the 7200BX. Anyhoo, I haven't had any issues with the receivers, but I'm never out there putting tons of hours on them. I have a couple simple spektrum 6 channel receivers (I forgot what they came in lol), and several 7-8 channel ones. I would say get it shot... no point in spending money on something if you have too. I think the only receiver I have with the safex tech on it is my TimberX... but I set it up with that off. And uhm, that's a fun plane too!!

[PawPaw]

I’ve done a little more research & figured out buying programming interfaces for the AR626a to change it about as much as just getting an AR 620 so ordered it too. I’ve been fingering this DX6e this morning & it’s really user friendly. Just gotta get used to the weight difference & overall feel. My Cobra tinkering continues but rapidly running out of excuses to keep it grounded so decided to spend more time on a 450. Also, my confidence level with this Demon FBL isn’t where it should be right now. For example, just when I thought my tail issue was sorted out I read a post from Alpha on a different thread where he stated “Demon needs 8* of tail pitch” which confirms the “2 ball length” instruction. So, I’m thinking it’s time to get on the phone.....

[PawPaw]

One thing’s for sure...once all the scale bits are mounted it gets real interesting trying to find a good handhold to pick it up without breaking something off. Think I will install a 30mm fan high in the doghouse to see if it will help cool around the motor area. Motor gets pretty hot just from short test stand run-ups & my camera PCB will be very close to the can when everything’s buttoned up. I already installed a 40mm fan on the Talon but really didn’t need it, so maybe it will pull enough heat out by itself.

[sfcfury]

One thing’s for sure...once all the scale bits are mounted it gets real interesting trying to find a good handhold to pick it up without breaking something off. Think I will install a 30mm fan high in the doghouse to see if it will help cool around the motor area. Motor gets pretty hot just from short test stand run-ups & my camera PCB will be very close to the can when everything’s buttoned up. I already installed a 40mm fan on the Talon but really didn’t need it, so maybe it will pull enough heat out by itself.

What temps are you running? I know everything 'feels hot'... but I bought one of those lil laser pointer temp guns, everything seems to be in the 90-110 range. All the servo's seem stay about 85-90, the ESC gets about 110-115. That tengu motor runs pretty warm (comparatively speaking) seems to be about 115-120 right after shutdown. It runs warmer than the scorpion did. Those are all temps while the mechanics were in the fuselage.... but I have yet to drive it hard. Of course more airflow the better!

[PawPaw]

I couldn’t actually measure it but guessing it’s at least the 110 you mentioned. That’s normal I’m sure but don’t have a clue what that camera circuit board can handle in a confined space. That screened opening at the top of the doghouse looks like a perfect spot to exhaust the fan. BTW, do you know what incidence angle the stub wings on the tail boom should be? Prob insignificant but a detail I’d like to get right.

[sfcfury]

I do not; I know that it moves, (most likely automatically with airspeed) but do not know it's max elevation /deflection angles. I personally was going to mount it with only a + 1 or 2 degrees angle. In most in flight pictures that's what it looks like.