Smartmodels AH-1 Cobra (600 size) Build thread

[HornDog]

This is my first build so I am applying the skills learned here in the forum to completing this build. The project is a continuation of cobra_attack's vision for this fuselage and with steady, decisive progress I aim to see it completed and properly functioning! I plan to post progress pics while working on this build and will be looking for guidance as well to make it the best it can be.

THANKS to cobra_attack for all the painting and rivet details so I can focus on the mechanics and flight.

LET's get this bird airborne!

[HornDog]

The side frames included with the kit are metal, so I added metal bearing blocks, and aluminum bottom frame plate to keep her solid. The front lip of the bottom tray will be removed to make room for batteries below the canopy but the included mainshaft is just right to give proper clearance for a FBL head on this kit.

Planning to use the slant gear of the new 600 main gear setups and the 5-point main gear hub as well. Still working on the tail rotor issues though... the classic BELT vs TT debate in terms of longevity and durability for an elevated tail.

[JoseReyes]

Originally Posted by HornDog

This is my first build so I am applying the skills learned here in the forum to completing this build. The project is a continuation of cobra_attack's vision for this fuselage and with steady, decisive progress I aim to see it completed and properly functioning! I plan to post progress pics while working on this build and will be looking for guidance as well to make it the best it can be.

THANKS to cobra_attack for all the painting and rivet details so I can focus on the mechanics and flight.

LET's get this bird airborne!

Very nice.

[ah_liang]

Looking forward to the build thread ... I too am deciding to go for the cobra or airwolf.

[HornDog]

Originally Posted by ah_liang

Looking forward to the build thread ... I too am deciding to go for the cobra or airwolf.

Here's what I learned in one short week. Most of the scale fuselages have an inline tail rotor... and that reason is because the elevated tail of the Cobra/ Huey/Blackhawk can be a challenge!! But not impossible.

Also the Cobra has a VERY narrow profile compared to other models so the main gear almost always will be wider than the fuse. So this kit covers it by opening the munitions wing supports for the gear to extend beyond the body into that recess. Without it, the gearing would be WAY OFF for anything smaller. So plan according to the space inside the fuse you pick and have fun! The instructions will be vague so you have to learn as you go!

[HornDog]

Ordered the main gear case so I could start the mock up of the frame. Got the OWB and gears in place. Added the sleeve. The when I tried to assemble to the main shaft.... it won't fit! Took it apart to measure and I have a true 10mm shaft and a 9mm sleeve. Since this was reported to fit 600/600E/600E PRO I guess they standardized the shaft end to 9mm. So now the fun part... finding a 10mm sleeve that will fit the Trex Gear hub... yay!

[jstalnaker70]

very interested in this build as i too am thinking of buying a cobra fuselage for my trex 600cf

[HornDog]

Okay guys, looking for some assistance from the guys that have built this 600 Cobra already. I am looking to purchase the Cyclic servos and FBL head and unit for this heli and need some input. I am already having to have the original mainshaft included with the kit either re-manufactured to fit the 600E OWB hub or custom fabricated (both are options at this point). But what head will work well with the BeastX unit or 3GX (keeping the FBL unit as cost effective as possible since this will not be a 3D bird). Was looking at the RJX head for this build but is there a preference? This is my first scale build so keeping it close to the actual setup is preferred but not necessary. I would like to place this order by Friday so next week I can start some assembly during Spring Break. Also, outside of the ALIGN DS610s I am looking at as a bundle, what servos might be great long term for this scale heli that aren't gonna cripple the pockets? Thanks!

Next purchase will be the tail drive solution. Saw some great options at the Birmingham Fun fly (Thanks Rich from ReadyHeli and CoptorDoctor for all your help!) and I am pretty convinced to go with a flex shaft. PROPERLY installed and sized, this seems to be an easier maintenance option for this build given the limited space in the fuse. Dr. Tim has been VERY helpful with researching this and the adapter for lower placement of the drive.

SO on to my next question: Where can I find a 5mm flex shaft cable and sleeve for this heli? I want a stronger cable JUST to make sure there are minimal issues later if any related to torque.

[JoseReyes]

Originally Posted by HornDog

Okay guys, looking for some assistance from the guys that have built this 600 Cobra already. I am looking to purchase the Cyclic servos and FBL head and unit for this heli and need some input. I am already having to have the original mainshaft included with the kit either re-manufactured to fit the 600E OWB hub or custom fabricated (both are options at this point). But what head will work well with the BeastX unit or 3GX (keeping the FBL unit as cost effective as possible since this will not be a 3D bird). Was looking at the RJX head for this build but is there a preference? This is my first scale build so keeping it close to the actual setup is preferred but not necessary. I would like to place this order by Friday so next week I can start some assembly during Spring Break. Also, outside of the ALIGN DS610s I am looking at as a bundle, what servos might be great long term for this scale heli that aren't gonna cripple the pockets? Thanks!

Next purchase will be the tail drive solution. Saw some great options at the Birmingham Fun fly (Thanks Rich from ReadyHeli and CoptorDoctor for all your help!) and I am pretty convinced to go with a flex shaft. PROPERLY installed and sized, this seems to be an easier maintenance option for this build given the limited space in the fuse. Dr. Tim has been VERY helpful with researching this and the adapter for lower placement of the drive.

SO on to my next question: Where can I find a 5mm flex shaft cable and sleeve for this heli? I want a stronger cable JUST to make sure there are minimal issues later if any related to torque.

Have you considered torque tube conversion?
Check this thread. http://www.rcgroups.com/forums/showt...1489588&page=6

[HornDog]

Originally Posted by JoseReyes

Have you considered torque tube conversion?
Check this thread. http://www.rcgroups.com/forums/showt...1489588&page=6

Yeah.. couldn't find a vendor that sold the good RC Aerodyne elbow on this side of the water. Only their European site. Seen both and they both are cool. Do you know a vendor? I would like to start tackling this issue as well VERY SOON!

[JoseReyes]

Originally Posted by HornDog

Yeah.. couldn't find a vendor that sold the good RC Aerodyne elbow on this side of the water. Only their European site. Seen both and they both are cool. Do you know a vendor? I would like to start tackling this issue as well VERY SOON!

It seems that every where I looked in the USA is out of just about everything multiblade period... Kin from smart model does have the kits, it doesn't take that long to get to the US... I know is not overnight but is worth the weight...

[HornDog]

Originally Posted by JoseReyes

It seems that every where I looked in the USA is out of just about everything multiblade period... Kin from smart model does have the kits, it doesn't take that long to get to the US... I know is not overnight but is worth the weight...

I was actually trying to find the black TT elbow I saw that comes with the German Helicopter on RC Aerodyne's site.. saw two of them installed in Birmingham and they seemed to work very well with a 3 bladed tail.. my two blades should work well. SO far I haven't solved how to interface the contour drive step down part to a stock Trex 600E so I may be forced to do the TT option. So far only RC Aerodyne's European site has the elbow piece itself solo... tempted to call them and see if they can import one to RC Aerodyne for me since they don't ship to the US....

on the good note, I do have an assortment of pieces coming in for the frame itself. And it looks like I will have to separate the tail section (cut right through the glue) to install ANY tail option and reinforce the the fuse to support the tail....

[JoseReyes]

Originally Posted by HornDog

I was actually trying to find the black TT elbow I saw that comes with the German Helicopter on RC Aerodyne's site.. saw two of them installed in Birmingham and they seemed to work very well with a 3 bladed tail.. my two blades should work well. SO far I haven't solved how to interface the contour drive step down part to a stock Trex 600E so I may be forced to do the TT option. So far only RC Aerodyne's European site has the elbow piece itself solo... tempted to call them and see if they can import one to RC Aerodyne for me since they don't ship to the US....

on the good note, I do have an assortment of pieces coming in for the frame itself. And it looks like I will have to separate the tail section (cut right through the glue) to install ANY tail option and reinforce the the fuse to support the tail....

To bad the german site does not ship to the US. I have tried contacting them never got a response back...

[HornDog]

Well, I'm getting a few other parts in until I sort the tail issue and the main shaft machining needs. Got DS610 servos for cyclics and I'm planning to install them today. Might cut the fuse open (I cringe just thinking about it) Monday and start the front mechanics installation process.

Gonna try to shift the front skid also. So far it is directly in the way of a potential mounting position inside the fuse so adjustments are being made. Gonna also start wiring in lead extensions for lighting inside the fuse. Thinking of maybe some form of quick connector to allow me to separate the tail boom and fuse pieces from the frame and disconnect them easier. Also considering mounting the tail servo farther back into the tail area to reduce travel. Hard getting measurements inside there but not impossible.

Still undecided also on a 6S setup or 12S. Cockpit area is the problem. Limited space... and I STILL need to decide on a Motor and ESC combo that will fit these metal frame sides but be a bit more power than anticipated. With all these metal parts and fuse she will be heavy. No doubt! Well, the rookie continues his quest.....

Alright, Alright, Alright! You gonna learn today! LOL!

[HornDog]

Got the cyclic servos installed... wasn't too bad. Glad I had a kit full of screws and nuts on hand... forgot this was a METAL frame... and the stock screws had nothing to screw into!

Few pics of setup so far. More to come.

[HornDog]

Was getting a few questions on the progress so I made a video for my channel. Still got parts coming in and I haven't decided on the motor or BEC yet but the ESC arrived as well as other parts. Got the entire tail rotor assembly ordered today so it is here by Wednesday. Working with Youth Challenge here in my city for a Flight demo/ Family day event with buddy boxed Blade SR120 helis so I've been SUPER busy planning and coordinating. Hoping to start the tail mock up next week and start shooting video for that part as well. Check it out and subscribe if you like!

[HornDog]

Started working the fuse to prep it for a fitting. Ordering the V-Bar within the next month... got the servos, new servo arms (other ALIGN arms were WAY too long) and got the RX setup on my DX8. Installed the KDE Anti Rotation bracket and gutted the fuse wings so the main gear can fit inside of them. Opting for a 12S setup on this heli.. still haven't calculated what KV motor I need just yet. But still debating on making the turret work... at least spin and turn with the rudder. Ordered http://www.readyheli.com/MIK4149-V-B...e_p_35361.html

for the rotor head. Designed to work with Mikado V-bar and Align parts. Plus I think it looks pretty cool exposed through the top of the fuse.

Planning to get all the forward mechanics finished this month and go to my place of ZEN to tackle this elevated tail. Already assembled the tail rotor hub and test fitted the wood ribs and supports for the raised section. Trying to waite out RC Aerodyne on this elbow otherwise I will go off the deep end and attempt the flex shaft.... kinda skeered to do it as a first scale build. LOL!

[HornDog]

A few progress pics of the build so far.

I think Wifey is gonna get me bout working on her new table set..... LOL!

[HornDog]

Well, I didn't like the plastic M197 gun barrels that came with the kit. So unless I can find a more scale looking replacement my temporary solution is brass and aluminum tubing. Measured and cut a few pieces and epoxied them together. Still letting the pieces set up before I lightly sand, prime and pain them. Still thinking of motorizing the turret barrels to rotate but here is progress so far. Also got the Mikado head setup temporarily while I wait for the main shafts to return from being machined.

[HornDog]

Still doing cosmetics while awaiting parts. Secured a motor to turn the barrels and planning to use a servo to move/ jog the turret to mirror rudder movements. Trex 500 Main shaft bearing (old one from a crash) epoxied in to support the assembly and allow a smooth rotation left and right. Not much else besides added wood ribs/ braces to the rear of the front half of the fuse... should stiffen it up and allow ease of access for maintenance. Still looking like RC Aerodyne won't make it easy for me with the ONE part I am waiting on to start the tail mock up .... So flex shaft it may be!