500 Size scale heli - Building in progress.

[Super-Hornet]

After keeping one 500 size fuselage for quite sometime, it is time to start building it.

To start up, I decided to build using parts for TRex500 size, Pro version. This will be the 1st 500 size torque tube, elevated version.

Since TRex500's main rotor is default to spin Clockwise rotation, the real heli for the scale I going to build spin in Counter Clockwise rotation. Thus, I need to modify the one way bearing in 180Degree reversely.
In other word, knock out the one way bearing and fit it back in opposite position.


Obstacle #1:
Building TRex500 size mechanical, realized that the frontal tail torque tube that I bought was wrong. It was for TRex500 non pro version. The width is wider than the Pro version.
Thus, spending some time to go Rotor hobby to get those missing/incompatible parts.

[Super-Hornet]

Initially I intend to use Align servo, DS510, for the cyclics but too bad Rotor Hobby do not have stock for 3 sets. Thus, I switch to Hitec HS-5245MG instead.

Obstable #2:
Using HS-5245MG encounter one problem for TRex500Pro is that, the servor is too long it cannot put 2 servo side by side for the cyclics. So, a spacer is require to move the servo outward a bit.
I using screw nut as the spacer instead.

Obstable #3:
Due to the swash plate follower is fixed to the main rotor hub, there is no way I can adjust the phasing mechanically. Even when the heli spin at Clockwise rotation, the cyclic to blade grip is not in 90Degree.
When using the main rotor for Counter Clockwise rotation, the phasing is out even more.
Thus, i decided to use trailing edge controlling instead. As for the non 90Degree phasing, this one have to do offset by electronics instead.

Obstable #4:
Due to the design of this Align head, the linkage between swash plate and blade grip is in slanted angle.
I do not like this kind of design because during loading (or spinning), changes in blade pitch (either by cyclic or collective), will have some force acting on the inner swash plate in diagonally angle.
This will cause the inner swash plate to turn a bit. Thus, decided to build a "Z" shape linkages out from Raptor linkages and bend it in a "Z" shape.
By doing so, the angle between linkage to blade grip and linkage to inner swash plate is in 90Degree (perpenticular).

Next build will be tail portion.

[Adrianli]

Subscribed.

Can use smaller pics???

[Super-Hornet]

Tail Building - With Tail Rotor on the Left Side.

Tail building so far so good.

Tail building so far so good.
Elevated tail gearbox is using Align build for their 500 size scale.

Because the scale I going to build is having its tail rotor on the left side (to follow what the full size heli I going to reference to), I need to flip the tail rotor casing on the left side.

The Align tail boom mounting slot and hole is position in such a way that, it allow me to flip both elevated tail boom gearbox and the elevated tail boom in reverse postion and that allow me to mount the tail gearbox for the tail rotor on the left.
Together with main rotor spinning at Counter Clockwise rotation and the tail rotor on the left, the torque tube and gearbox allow the tail rotor to spin upward as well (just like in the full size heli).

I also change some of the elevated gearbox's mounting screw to a longer screws in order to allow me to mount a makeshift tail skids. This tail skids is just a temporary and it is use to protect the tail in case of landing tail 1st. (Parts from TRex450 linkage)

[Super-Hornet]

Now, since the tail rotor is on the left, that required to modify the tail rotor pitch control (The 'L' level that control the tail rotor pitch fork) so that it can be mounted at the bottom for tail rotor on the left.

To do that, it required a longer screw to mount the L level on much lower than usual. Because of the L level is now lower than normal, the pitch fork's linkage ball required to move downward (or make it longer mounting) as well.

All this is done using longer screws, some washers and some nuts.

Longer screw = In order to mount then in lower position.
Washers = For spacer, for filling gaps and also to contact point for the bearing.
Nuts = Two nuts to act as interlocking mechanism so that the screw will not get loosed (better than threadlock )

Since my friend encounter heli crash due to screw came loose on pitch fork's linkage, I also notice there is a "weak point" in the linkage design because the screw is too short. Too tighten it and there is too much friction on that area and that causes "not smooth" tail rotor pitch control. Too loose and that will have problem of screw came off. Applying threadlock before screw in the screw to the tail rotor blade grip and the threadlock will touch the copper tubing/bushing and causes bushing to "lock" to the screw instead (thus friction).

With that, I decided to replace the screw to a much longer screw and then use a nut to hold the screw instead. By doing so, the tail rotor pitch fork can have "loose effect" movement and yet the screw is tighten to the nut (and thus will not get loosen).

[Super-Hornet]

Mounting RX, ESC and MicroBeast

Finally, mounting RX, ESC and MicroBeast. At the final fuselage stage, RX, ESC and Microbeast will be mounted in front of the fuselage and possibly on the fuselage frame instead. But to test this heli, I need to temporary create a mounting platform for those 3 items. Thus, I use a P.C.B. instead. Drill two holes for mounting the landing skids and also to hold the P.C.B onto the heli.

ESC (Castle Creations ICE 75) will be running on 6V BEC, and Governor mode.
Microbeast already program to have phase offset for 10Degree (this is due to the rotor head design).

Oh... BTW, the tail rotor is for Align TRex550 size. The reason I use that tail rotor blades is because:
1. 500Pro is having main rotor to tail rotor of 1:4 ratio. This ration is too for for multibladed (4 bladed).
2. Bigger tail blades should solve the problem of tail authority too low because it has more "surface area" and also this heli to run a lower main rotor RPM.

Now, heli is now ready for test flight.

[Super-Hornet]

Building "Lakota UH-72A" Scale

The scale heli I going to build in this thread is, "LUH-72A" (which stand for Light Utility Helicopter) or also known as "Lakota UH-72A".
Fuselage is from Smartmodel EC145 for 500 and 600 size heli. The box don't even come with the manual. But I manage to download a PDF copy of the "should be correct" manual from internet. (Phiew!)

The color that comes with it appeared to be wrong color. It looks more like Nato green. The correct color should be Olive Drab.

I haven't building it...but will start it as soon as possible

[Super-Hornet]

Building this scale take longer time than usual. This is probably due to it is all in pieces. Need to glue the wooden parts to the fuselage.

Alignment can be pain in the ass.

Here are the top parts screwed to the main body. I don't care about the "dirtiness" or scratches on the paint job during building because I have the intention to repaint it with the correct color of "Olive Drab".

[Super-Hornet]

Update

Tested flew the heli and it was flying very well.
Heli already dismantle in order to put into fuselage for testing.

Here are some of the pictures of the fuselage. The version I have, the top part is a single pieces...especially at the rotor area. That make installation of heli to fuselage is quite tedious. So, decided to cut the top part to two pieces. Photo shows the process of cutting it slowly using box cutter knife.

Note.. the tail servo is from Align and turns out to be quite good. When test flying... I set it to 80% tail gyro gain. It turns out to be tail response too sensitive...or tail servo too fast. Tune it down from 80 to 70 and lastly 60%.

[army627]

bro presently i'm building my UH-1b huey for 500 size...i the belting system to toque tube..got my main blade turn counter clockwise but i got my tail turn clockwise..do u got the same too?

[Super-Hornet]

Assuming that u use the elevated gearing like I use, your main rotor will spin CCW like in UH-1B.
The tail rotor for UH-1B should be on the left side like in the real UH-1B. Thus, the tail will spin with tail rotor spin upward toward the main blades.... which is correct to the real full size UH-1B.

EDIT: Oops! After check with pictures of full size UH-1B, the tail is on the left and spin downward. So for your case, looks like u have to modify the tail rotor shaft's bevel gear. U might able to get some shaft with the same diameter. Then flip the tail gear bevel gear 180Degree. Then some shaft collar to lock the bevel gear in place. That will be able to change the tail spinning direction while maintainning tail on the left side.

[Super-Hornet]

Another method u can try...which is much easier to do... is to use flexible drive shaft that used in R.C. speed boat.... and use it to replace the elevated tail. So, u will have mixture of torque tube and flexible cable. Note that the flexible drive shaft got CW and CCW version. So, make sure u get the correct one.

Based on my visualization..using the flexible drive shaft to replace the elevated tail, and normal trex torque tube tail gearing, u should get correct tail rotor position and spinning direction.

Search this forum for my old post of my UH-60 Pavehawk scale helicopter to see how I did the mixture of torque tube and flexible drive shaft.

[army627]

http://www.daddyhobby.com/forum/attachment.php?attachmentid=121036&d=1360557960&thumb=1&stc=1

This is the pic of my tail position...

[army627]

bro,how u do urs?is ur tail and main blade turn ccw?

[Super-Hornet]

I am doing UH-72A... In full size Lakota, the main rotor spin CCW with tail on the left side..tail spin upward (or facing tail, spin CW).

Thus, I follow exactly like in real UH-72A.