Roban AH-1W Cobra 700 Size Scale Helicopter

[sfcfury]

What Ppaw said. Lol... I'm here to ask Delta questions not the other way around ... I just don't have enough experience in general to give any worthwhile thoughts on it

[PawPaw]

Oh, forgot to add that it might be a good idea to couple the 2S ground to the ESC ground as is suggested in the Roban manual “ Certain configurations without this ground interconnection have led to a loss of signal at the ESC from the receiver due to EMC effects.” The receiver switching circuit probably has this already but can’t say for sure.

[PawPaw]

I guess it would depend on that receiver’s diode circuit. A 2S pack is 7.4v and BEC’s run 6.0v so my thoughts are you would benefit more from using the BEC as primary & 2S as backup as you suggested. Would be easy to test with a multimeter on the bench too.

[F106DeltaDart]

I’ve been slowly plugging away on my build. Built up a test rig for the mechanics, and started working on wiring. The stock tip on my new soldering iron proved too thin to heat up the 10AWG wiring for the ESC, so now it’s another week waiting for the new tips to show up.

I am struggling to figure one thing out though.. I am using an AR12310T Powersafe Spektrum receiver. This has 2 inputs for batteries to connect to the rx. If one is starting to run low, it automatically switches to the other. What I’ve been trying to figure out, is whether I can connect a Castle Pro BEC to one of those battery inputs. That way I only need one rx battery, and it only serves as a backup in case the BEC fails. Anyone know if this is ok? All I’ve been able to find searching around is people who have used batteries only..

[PawPaw]

Yeah, it’s that one time for sure. I did see the general write ups say the 4025 is a 600 class motor, even with the same kV as a 4035 which is 700 class. The Scorpion 4035-560 is a good fit in my Cobra with the camera pcb mounted cockpit rear but your 4500 series would likely touch it. The B407 is pretty tight in the doghouse anyway so need to figure out how much diameter there is to work with there. Thanks for the info!

[sfcfury]

With that being said.... (and throw extra confusion and indecisiveness lol) if you go back and look at scorpion motors... you have different 'series'... so like HKII, HKIII, HKIV etc... and when you compare their older HKII 4035 motors to a HKIII 4025... even the peak power draws are similar.

[sfcfury]

So out the gate... again i'm not a SME... but from what I've read (at least concerning scorpion motors) 4025's are listed as for 600 size helis. 4035 is for 600-700 size... usually if you get into the numbers, the 4035's can handle more peak power draw (watts/amps).... which in scale flying probably wouldn't be an issue... except for that one time lol.

[PawPaw]

Not exactly Cobra related, but I’m spoiled here. Specing out a 700 B407 & curious about motor nomenclature: I read the 1st two digits of a motor is the stator diameter & the 2nd two digits are the stator thickness, but what would the practical difference be between a 4035 and a 4025 when both motors have the same kV rating? Heat dissipation? Pickings are getting slim in the marketplace & doesn’t appear new stock is flowing yet so don’t want to pass up a 4025 that’s available now if there’s not a major difference. Thanks!

[DCORSAIR]

Not hard to figure out there’s few spots to grab on a Cobra once all the scale bits are glued on. All it takes to remember the wrong way to pick it up is having to glue them all back on two or three times.

Sweet, looks awesome...........

[sfcfury]

Not hard to figure out there’s few spots to grab on a Cobra once all the scale bits are glued on. All it takes to remember the wrong way to pick it up is having to glue them all back on two or three times.

Looking good! I like the camo version... To be honest I usually pick mine up by the rotor head... Of course I don't just snatch it up, but I figure that's weight is while it's flying. But yes... with all the small pieces attached, it's a test of patience on picking it up or loading up without knocking something off.

[PawPaw]

Not hard to figure out there’s few spots to grab on a Cobra once all the scale bits are glued on. All it takes to remember the wrong way to pick it up is having to glue them all back on two or three times.

[sfcfury]

Details never seem to end or either I’m just making excuses. Sfc, I’m absolutely not trying to hijack your thread but can’t seem to get all my questions on one post: Did you install those “EVA Distancers” on yours? If so, next time it’s convenient would you post a pic? I can’t make hyde nor hair of the pic in the manual. I get the intent of the critters but just don’t find the obvious mounting spot. Thanks!

Ppaw!! Good day! I haven't permanently mounted those yet either... I've identified pretty much where I am going to put tho... I will take a picture when I get home.

[PawPaw]

Details never seem to end or either I’m just making excuses. Sfc, I’m absolutely not trying to hijack your thread but can’t seem to get all my questions on one post: Did you install those “EVA Distancers” on yours? If so, next time it’s convenient would you post a pic? I can’t make hyde nor hair of the pic in the manual. I get the intent of the critters but just don’t find the obvious mounting spot. Thanks!

[DCORSAIR]

Yep, some say no and some yes, I just can't help it, I have to check things and make sure it's not going to fly apart, so I run mine at the throttle curve I plan on flying with and that is 70-80% with no blades, never had an issue yet doing it that way, there is no smell with the blades on though, I will say that.

[sfcfury]

I have read arguments kinda going both directions on if it's bad to run without blades, and I'm inclined to go with the it's okay to do so train of thought... I just wouldn't be banging the sticks up and down, b/c I think the sudden spikes of power draw might be the more dangerous part to the components (b/c of the no load situation)- but I also have the headspeed change setting set to medium, so it's just not gonna just dump power up and down anyways. I recently ran up the tengu with no blades, just bring it up slowly looking for vibrations etc, went all the way to IU2... watching etc... no issues. Of course its much a brand new motor, hasn't even been in the air yet, and when I shut it down, (being that I was right on top of it) and I got a lil bit of that 'hot electric' smell. PP... I think if anything, running it your 30% setting is probably a little bit harder on the CC ESC, b/c its my understanding that they run hotter when the are trying to govern that low speed. Heat is always the number one enemy... but with that being said, right after a test, or hover flight, I will feel the ESC or Motor, and be like dayum that is HOT!! Go get the temp gun and it's only 5 degrees F hotter than 'usual'... and still no where near the ball park of the max temp of the motor or ESC... My NASA calibrated hand temp gauge let me down again

[PawPaw]

Glad to hear it’s kinda normal, at least. I never pulled a positive pitch & the cockpit was installed so the motor can didn’t get much air movement. I do have a fan on the ESC but can’t believe that made much difference. Thinking maybe the ESC?

[DCORSAIR]

After one more removal of the mechanics (servo extension clips are to prevent leads pulling loose, duh) got it back together & blades mounted. It spun up just fine & nothing flew off or vibrated loose. The motor didn’t seem to heat up as much with the blades on, either. My camera location behind the cockpit seems fine too. Was tempted to get her light on the skids but need to figure out if I’m in the ballpark with tail gyro. I’m positive it’s in HH mode and tail’s not trying to “scoot” so probably ok but I want to find out how much my tx gyro slider inputs change the dampening rate. I left the long computer lead attached to the FBL so I’ll hook it back up to the computer this afternoon.

You know, it's funny you mentioned your motor heated up and seems fine with the blades on, I did the same thing on my Hughes 500, spooled it up to check for vibes without the blades and the motor got really hot, it actually had a hot smell to it, thought something was wrong for sure, but now with several flights on it, the motor is just a little warm even if I'm just sitting there checking tracking, then I read somewhere that your not supposed to spool up full throttle for to long without blades on, didn't know that but I guess it's true, no air blowing over the motor?

Maybe someone can varify if that is true??

[PawPaw]

After one more removal of the mechanics (servo extension clips are to prevent leads pulling loose, duh) got it back together & blades mounted. It spun up just fine & nothing flew off or vibrated loose. The motor didn’t seem to heat up as much with the blades on, either. My camera location behind the cockpit seems fine too. Was tempted to get her light on the skids but need to figure out if I’m in the ballpark with tail gyro. I’m positive it’s in HH mode and tail’s not trying to “scoot” so probably ok but I want to find out how much my tx gyro slider inputs change the dampening rate. I left the long computer lead attached to the FBL so I’ll hook it back up to the computer this afternoon.

[PawPaw]

Weird thing just happened. Finalized mechanics install & tried a quickie spin up inside the house without main blades, of course. Hit the IU switch 1 which I’ve got set to 30% (1150) & it spooled up just fine, then shut off at the 30%, then caught itself again back to the 30%. I did note CC says the 30% is hard to govern but I’ve not had this happen in many previous test spins. I’ll get it outside tomorrow for a real test.

[PawPaw]

Wow