Roban AH-1W Cobra 700 Size Scale Helicopter

[PawPaw]

A 700 TREX unit?

[PawPaw]

A 700 Trex unit?

[sfcfury]

Yes- this one HN7053B 700N Metal Tail Torque Tube Unit.... Just b/c I was trying different things... when it came in, it's slightly wider than the Roban. That's when I ordered the Align 600ESP Metal Tail Pitch Assembly / Black AL-H60250... which fit perfectly on the roban assembly. The 700 size one fit the tube and the drive shaft, was just slightly wider. I don't have a complete 600 size assembly, but I would have to believe the entire assembly would be a drop in replacement.

But the fact the replacement tube is a 1.3inches longer than mine, got me wondering about the mechanics and size of everything. I know your mechanical setup for the tail that's in the main mechanics is different from mine.

[DCORSAIR]

Yes- this one HN7053B 700N Metal Tail Torque Tube Unit.... Just b/c I was trying different things... when it came in, it's slightly wider than the Roban. That's when I ordered the Align 600ESP Metal Tail Pitch Assembly / Black AL-H60250... which fit perfectly on the roban assembly. The 700 size one fit the tube and the drive shaft, was just slightly wider. I don't have a complete 600 size assembly, but I would have to believe the entire assembly would be a drop in replacement.

But the fact the replacement tube is a 1.3inches longer than mine, got me wondering about the mechanics and size of everything. I know your mechanical setup for the tail that's in the main mechanics is different from mine.

Roban did make improvements since the RCAerodyne days, now that MRC has picked them up there seems to be some improvements along the way, so your new tail tube will put the tail rotor up taller out of the fuselage?

[sfcfury]

So, doing a little sound check... I have an APU sound initially, and then I toggle the actual engine start up.... I think I will set the Nav lights to be on initially, and then the strobes will come on with the engine start up.... nothing exciting. Matching the blades with the spool up is a task lol... while my engine spool up is pretty slow actually, the blades start turning much quicker than scale! Shutdown is easy tho

[sfcfury]

Managed to chase get most of the vibration out of my tail... had to break out the prop balancer on the blades!! The blades were all kinda out of whack... trying to get them to match on the center alignment, I actually had to add weight to the 'heavier' blade... which made it that much more heavy... So I ended up having to add 4grams of putty and then sanded it down a touch. When I tried to spool up with the blades at identical weight the vibration in the tail was horrible. So added weight, took it off, back on the balancer, back off, sanded some more... so now they are pretty dialed in, one blade weighs 188.69 grams and the other is 189.22... go figure!

[PawPaw]

Wow! Awesome vid sfcfury...now I gotta copy you again & buy sounds. Odd on the blade balancing. Doesn’t seem to make sense, unless you had a bent main shaft...which woulda showed up before now. Better check mine!

[DCORSAIR]

Wow! Awesome vid sfcfury...now I gotta copy you again & buy sounds. Odd on the blade balancing. Doesn’t seem to make sense, unless you had a bent main shaft...which woulda showed up before now. Better check mine!

I was thinking the same thing, that is odd that he had to balance the blades like that to keep the vibes down, I never had to do any that way.?

[sfcfury]

Definitely not a bent shaft... and I never did all that with my blades before I started chasing down my OH6 tail issue last month... although it's not like I've built a lot of heli's either! But I had found a video about blade balancing for the helicopters, and after I had noticed tail vibrations on the test bed... but then noticed that there were zero vibrations in the tail when I did a full run up with out them... like the tail was rock solid... I figured blade tracking, balancing etc... My tracking was pretty solid out the gate b/c I use the soko ( I really like that thing). I think I ended up only making 1 half turn adjustment on a blade for tracking... so that left balancing. The first time I put them them on the prop balancer, it was very clear that one blade was heavier than the other. I had watched this video, and another with a guys putting his 500 blades on a prop balancer.

[sfcfury]

So my first video in the air.... Well the good news is that I think that I have eliminated most of the vibrations that I can... feels pretty solid. The bad news is that my piloting skills were sucking butt... and the harder I tried to keep it in one spot the more it didn't want to stay!! In my defense that was my new gopro stand, and I was trying to not get too close and blow it over! (that's one of my excuses and I am sticking to it!)

[sfcfury]

And well hey... you gotta have a lil slo mo action too right??

[DCORSAIR]

And well hey... you gotta have a lil slo mo action too right??

Looks great, once you get it up a little higher out of ground affect and out in the open I bet it will settle down some, oh and now I understand how you did your blades and why one is heavier, sorry, at first I thought you just stuck some weight on one blade and made it heavy and went for it, but now I see you found the CG on each blade then added the weight, thats how I do it, maybe not as perfect as he did in the video, but close.

[PawPaw]

Yes that makes more sense now. Thanks for posting the how to vid also. Your AH-1W looks great & glad you got the vibe issue sorted. Still got mine to do but been distracted with the B407 last few days. I’m thinking I’ll end up shortening my short vertical tube to get a better shaft lockup but we’ll see.

[sfcfury]

Lol.. yea I'm definitely no expert, but I know better than to just slap random weight on the blades . ... However b/c I only ever dealt with 450/500 size (and only built a few at that) I never really got into the weeds on CG and balancing of the blades, and I must've just really lucked out in those areas up till now b/c I never had those issues.... but now I know!! Clearly it seems the bigger the blade, the more important CG/Balance are... I'm definitely liking the way its running now. Just have to get my lights sorted out and get all the pretty little details on!

[JFandL]

Lol.. yea I'm definitely no expert, but I know better than to just slap random weight on the blades . ... However b/c I only ever dealt with 450/500 size (and only built a few at that) I never really got into the weeds on CG and balancing of the blades, and I must've just really lucked out in those areas up till now b/c I never had those issues.... but now I know!! Clearly it seems the bigger the blade, the more important CG/Balance are... I'm definitely liking the way its running now. Just have to get my lights sorted out and get all the pretty little details on!

Outstanding so far!!!

[DCORSAIR]

Lol.. yea I'm definitely no expert, but I know better than to just slap random weight on the blades . ... However b/c I only ever dealt with 450/500 size (and only built a few at that) I never really got into the weeds on CG and balancing of the blades, and I must've just really lucked out in those areas up till now b/c I never had those issues.... but now I know!! Clearly it seems the bigger the blade, the more important CG/Balance are... I'm definitely liking the way its running now. Just have to get my lights sorted out and get all the pretty little details on!

I didn't figure you slapped on some weight and went for it exactly like that.

Love the Cobra, can't wait for your flight report.

[DCORSAIR]

Any flight reports from you guys with these Cobra's?

I ended up letting my big AH-6 got to a good home, sadly I just didn't need two of the 800 size helis so I sold it, thinking about getting the Cobra...

[sfcfury]

Any flight reports from you guys with these Cobra's?

I ended up letting my big AH-6 got to a good home, sadly I just didn't need two of the 800 size helis so I sold it, thinking about getting the Cobra...

Whatttt.... sold one of the 500's!! I have been working a lot , and working on my hobby room... a lil diy home project. It will add 100 sq ft to my house (all for my RC stuff)... I should be finished this weekend. I had the helical cut gears come in... so my intent is to really get the cobra all finished up. I only had about 30 days of covid time lol... but I did put it to good use! OAN, my OH6/500D 600 size funkey fuselage finally shipped.... So I plan on selling my 500 sized one as well.

[DCORSAIR]

Whatttt.... sold one of the 500's!! I have been working a lot , and working on my hobby room... a lil diy home project. It will add 100 sq ft to my house (all for my RC stuff)... I should be finished this weekend. I had the helical cut gears come in... so my intent is to really get the cobra all finished up. I only had about 30 days of covid time lol... but I did put it to good use! OAN, my OH6/500D 600 size funkey fuselage finally shipped.... So I plan on selling my 500 sized one as well.

Yeah, I know, shouldn't have sold it, I have a physical health issue going on right now, kind of came out of no where, making it hard to use my right arm, so I can't do much right now as far as flying goes, I did keep my Magnum PI version for now because it has the new V2 mechanics and for some reason, it flies better than the AH-6 did. Oh well, if I do get over this issue, I hope to build another scale heli, just not sure which one yet, was looking at the Roban EC135, I like big..

[PawPaw]

Sorry to hear about the health issue, DC! Hope everything resolves quickly & life gets back to normal for you. Good news on the expansion project, sfc...sure wish I had more room here but came to the realization I’d just fill up more space with more projects anyway. Other than a couple of quick low hover hops my Cobra just sits on top of a bookcase awaiting this Gulf coast monsoon season to pass. Hopefully will have more Cobra news soon.....