RC Groups

RC Groups
    Scale Helicopters
        Build Log Stretching a T500 and installing it in a .50 size AS350 fuselage

#1 SidewaysLS4 Dec 25, 2012 10:16 AM

Stretching a T500 and installing it in a .50 size AS350 fuselage
5 Attachment(s)
I've been working on a T500 stretch for a few months, and I figure it is about time I get a build thread going :o

To start...this is what prompted this idea. I have a 500 size 3 bladed Plug-and-Play head. It formerly resided on this heli, a 500 size AS350. That heli got retired as the airframe got stretched and installed into a .30 JetRanger. But I noticed that the head could take 12mm thick blades...so that gave me an idea :D


I always liked the Funkey .50 size AS350. Pretty slick fuselage I think. And a nice sale at Heliworld got me to order an unpainted version.

Now how would one stretch out and make taller a T500 into a 600 size scaler? Grab both ends and pull real hard, lol.

To start, I adapted a Gaui X5 flybar main shaft to the frame as it is the longest 8mm main shaft that I am aware of. As I don't have a method to drill into hardened shaft stock, it'll have to do. To adapt this mainshaft to the Align main gear scheme, I ordered an HDX500 autorotation sleeve, which is 8mm straight though (I didn't want to think about trying to drill though the Align part either). Here's a shot of the HDX part next to an Align pattern part:


I drilled a hole for the J-bolt to match the Align pattern location, and then cut down the length of the HDX part. That got the Align main gear onto the Gaui shaft.

Moving on to the head, I didn't like the M2 screws that were acting as linkage to the grips. A little small for 600 size blades IMO. I started to look into M2.5 turnbuckles, but after a few samples from various vendors, I found that none of them had standard .45 pitch threads, and they weren't .35 pitch either. So then I started to look into M3 alternatives. I found that Lunsford Punisher turnbuckles were made with standard M3 threads.

So after going with the Lunsford parts, I then tapped the swash inner ring to M3 size to accept Align 5mm linkage balls (from the 700/600/550 FBL parts bin), and then got some Align 5mm 700/600/550 FBL swash to grip plastic links (that can fit a M3 screw). I also tapped the head's L arms to M3 to accept the turnbuckles.

The final result looks a little like this:



If you'll notice, I made the swashplate sit just off the top of the frames so it will be nicely hidden in the fuselage. It will be positive pitch only. I also cut and shorted the anti-rotation bracket so it will tuck under the fuselage nicely


Other details are some MKS servos on the swash. A MSH/Scorpion 880kv motor with 134T/11T Align 'slant' gearing, and a Hobbyking YEP 100A esc (direct YGE copy...with an excellent gov). And of course, the BeastX pictured.

I also got the Hobbyking metal base plate for the frame, added M3 screws to the frame/baseplate interface for better strength/rigidity as it will be holding the fuselage to the airframe. Good idea I figure.

Well, now that I finally got the build thread started...now I am committed to it, lol. I'll post details on the tail changes I made, and fuselage changes as well. But it's time for breakfast, so I'll do that later.

#2 prop bender Dec 25, 2012 10:54 AM

Nice work Sideways:D Love that as350 it's a very nice bird:) Looking forward to seeing it in the air. Ed

#3 cap231ex Dec 25, 2012 12:59 PM

Looks good Sideways good to see you get a build thread started .

#4 Keyrigger Dec 25, 2012 03:16 PM

That's a good start. It should be a good fit when all done. Take care.


#5 sidneyw Dec 25, 2012 07:12 PM

Sideways, what servos do you use?

#6 SidewaysLS4 Dec 25, 2012 08:03 PM

Thanks guys. More to come, but got sidetracked figuring out what was worn out on another heli + ordering parts


Originally Posted by sidneyw (Post 23619184)
Sideways, what servos do you use?

9660A+. Great servos, much tighter and better resolution than your typical DS510. MKS sells an outstanding product again

#7 sidneyw Dec 26, 2012 01:16 AM


Originally Posted by SidewaysLS4 (Post 23619467)

9660A+. Great servos, much tighter and better resolution than your typical DS510. MKS sells an outstanding product again

Thanks, I am a little leery of the torque.

#8 sidneyw Dec 26, 2012 01:16 AM


Originally Posted by SidewaysLS4 (Post 23619467)

9660A+. Great servos, much tighter and better resolution than your typical DS510. MKS sells an outstanding product again

Thanks, I am a little leery of the torque. Similar to Hitec 225mg at 6v. If that is enough I will get Hyperion. Have a spare 500 airframe, will follow how you are doing.

#9 SidewaysLS4 Dec 26, 2012 01:00 PM

Lots of leverage on the swash/grip setup with this head, so I think it should be ok. You should sample a MKS servo sometime...after those DS95's I got and now these, I am impressed.

#10 sidneyw Dec 26, 2012 01:18 PM

Ok, I have used Hyperion, liking them also DS13-TMG .... will get the head from TFmodel later on. See how you do first. Was able to meet a lot of interesting people/owners in this industry after 18 months. Hope I can do some scale buildings in this year.:)

#11 SidewaysLS4 Dec 26, 2012 01:35 PM

Some tail stuff
3 Attachment(s)
One of the things that I like to do on a scaler is getting the tail rotor out away from the fuselage to where it should be in comparison to the full size version. Makes for a quieter heli reducing that model airplane style prop noise that can occur with the tail rotor too close to the fuselage.

So, I used this as a guide to where the tail rotor should approximately be:


Now how to get that tail rotor out? Glad you didn't ask :p

I started with extending the pitch arm fulcrum point outwards using some spare clone tail spacers. Then I got some 3mm CF strips and whittled out some new longer pitch links for the tail grips. Combine that with some 4mm hardened shaft stock to make the new longer tail shaft...it looks a little like this:



I am using a clone tail box as it uses 2 screws to hold on the pitch arm pivot. In the past I successfully used an Align metal tail box which uses 1 screw in a similar, but shorter extension. This time around I figured 2 screws would be better, and I was looking to go cheap on this build (which kind of bit me in the a$$, I might expand on this a bit later on). Also, I'm using an Align plastic hub/grips/slider assembly...lighter than metal and better than clone.

If you will notice, I also changed out the tail pulley to a wider version. This is so I can run a 3/16" MXL belt. Stronger, and more common sized...which helps getting a longer belt sourced for sure. I found that the pulleys from Misumi-USA have a more usable shape than the offset-style stuff you get from Stock Drive Products. They are actually a little cheaper too...and in my case they shipped them out from Japan for me, aint I special, lol.

I changed the drive pulley to a 17T and the tail pulley to a 15T. This was so the 3/16th's belt could fit the boom better, and to get a 5.3:1 tail ratio. On the drive pulley I ordered a 4mm bore pulley, then drilled that out to 4.5mm to fit onto the splines of an Align tail drive pulley assembly (which had its original pulley pushed off the shaft). I recommend using an Align part for this as the splines are finer than clone parts, making the job easier. The tail pulley was a 4mm version JB Weld'ed to the tail shaft.

Well, that's all for now. Specifics of the boom materials and such can be found in Cap's stretching a 500 thread...same stuff, just longer

#12 SidewaysLS4 Dec 26, 2012 01:42 PM

First Liftoff
I thought I'd throw in a short clip of the airframe's first liftoff :)

The heli is using a 'matched set of 3' of the 600mm Rotortech CF blades

T500 to 600 first flight (0 min 0 sec)

#13 cap231ex Dec 26, 2012 02:11 PM

Nicely done Sideways , keep the pics and info coming on the build. :)

#14 SidewaysLS4 Dec 26, 2012 03:21 PM

Some fuselage reworking
10 Attachment(s)
Thanks :). More....

One thing that I think needs to be fixed on the Funkey AS350 is this. The skid positions...


Not quite right. So let's get busy...

Moving the skids closer to where they should be is fairly easy. On the front it involves simply moving the skid mounting blocks back and making a new hole in the side of the fuselage for the skid tube. In the rear it is a little more involved as you cannot remove the stock skid mounting blocks since they are blind-screwed to the floor. Funkey screws the blocks to the floor, then they glue the floor into the fuselage making this a permanent installation. I took a block of wood and drilled a hole in it for the skid tube, then glued it to the floor closer to the tail. And added the needed new hole in the fuselage. Here's a pic of the new locations on the left, and the stock locations on the right:


I didn't feel too comfortable with just a glued on block supporting the weight of the heli, nor with that block taking whatever hard landings the heli might experience. So I went nuts with some CF strip material I had left from the tail rotor mods, and my new industrial sized JB Weld :D.

First I glued on a cross-brace between the two blocks, then made a dam with some masking tape where the JB Weld would be dumped to strengthen the blocks and attach them to the stock screwed-on skid mounting blocks. I took some broken tools to make a "drill here" guide to the skid attaching screw holes I devised...


Yeah I know Hysol is the 'fancy' epoxy to be used in scale models...I figure if JB Weld is good enough to patch an engine block...good enough for a heli, lol :p

And the final result. I used some self-tapping screws as the skid hold-in screws. In the future I might get some capscrews so it doesn't look so ghetto :o. It's all going to be painted flat black, so maybe not. Now there is a bomb-proof skid mounting :)


While I was playing with various epoxies...it was time to get rid of that weird hole in the bottom of the fuselage. I hear that the hole is for something known as a nitro heli...must be something from the dinosaur era or something :confused: :D.

I started with taping over the hole. As I didn't have blue masking tape that wide, the next best thing I had was some gaffer's tape:


I then painted on a few layers of 5 minute epoxy on the inside. Which left this after the tape was removed:



Ready for filler. I used some MetalGlaze...good stuff (but no pics)

And a quick mockup shot of the new skid locations seen from the side:


After sanding and filling the fuselage seams and holes, it was time for a visit to the Professional Spraybooth.



I used some Rustoleum Lacquer in white. You really cant beat the price of it if you just want white. I'm still in the process of color-sanding and buffing/polishing, so no final result pics yet. I'm also thinking of trying my hand at "weathering", so the heli doesn't have that fresh off the assembly line look.

Well, that's it for now. Next I'll put up some stuff relating to mounting the airframe and fitting to the fuselage.

#15 Keyrigger Dec 26, 2012 09:39 PM

That's getting there. It is truly a shame that FunKey made no provisions for accessing the screws that hold the skid blocks in place. Your choice is to make a new mount as you did or drill a bunch of holes in to move them back. The first method is the one with the fastest and maybe less damaging result. This is where I am with my MD500 TD. You get to a point where you discover that some things can easily be changed to make the heli more scale-like and then there are those that are virtually impossible or would require destroying most of the body to change it to a proper scale configuration. I have chosen to leave sleeping dogs lie. Take care.


All times are GMT -5. The time now is 04:21 AM.