WH-300 3-Amigos build thread (3 ways of doing the same thing)

[KrisW]

Okay. . Throttle servo time.

I'm using a JR 4735 Analog servo for throttle. It's FAST, decently accurate, and has about 100 ounces of torque. More than overkill for the job.

I've been using .063" CF rods for throttle linkages for quite a while now. Installation is dirt simple. Use the end links of your choice, with 2-56 threads. Screw the threaded portion into the proper sized Ny-Rod, and cut it off about 1-1.5" past the threaded part. Slip the .063" CF rod into place to test fit (may need to be lightly sanded to get into place). Pull it back out, coat lightly with thick CA, push back into the nyrod and twirl slightly and wait for the glue to set.

DONE.

Repeat at the other end for the servo arm link.

Where the rod passes through the firewall, use the proper sized outer nyrod sleeve as a guid, to about halfway back to the servo, then mount the aft end of the nyrod sleeve on a proper mount. I used a piece of 5/8 x 3/4 balsa, stood on end, with a groove sliced down the middle, to secure the aft end of the sleeve. the sleeve fits right in the groove, and a couple of drops of thick CA scure it in place. This is then glued down to the bottom of the motor box, again using thick CA. Be sure to line the rod up with the servo arm as you are gluing the mount in place.

the servo is secured to the bottom of the motor box with a drop of GOOP adhesive rubber, and a single ny-strap. Once the Goop sets up, it's basically rubber, and the servo is NOT going anywhere. It's also decenly shock absorptive, so rubber mounting pads are unnecessary.

The cutouts in the side plates of the fuselage, for the switches, are for the SMALL switches. I happened to have one on hand, and put it in the right front switch hole. Being that it has a charge jack, it will be perfect. I'll be using a 2400 ma Fromeco pack for ignition, with a regulator between the switch and ignition box.

[KrisW]

Okay . .a few side notes here.

In the instruction manual, it says to set the CG on the wing spar . .. .

Hmm. . foam wing, no evident spars. . .

(SHRUG) seems to me the spar is over the wing tube, so I'm going to set the CG centered on the tube, which is approximately 30-32% of total chord, a nice conservative positioning for most airfoils.

So I put three servos on the tail plane (to simulate 2 servos and linkages), 18 ounces of lead at the back anti-rotation pin point (about how much weight is going to be there with the wings in place and fitted with servos), put he cowl and prop/spinner on, hatch on, and left the canopy off, and lifted teh plane on the center of the wing tube (this IS a wings-off CG check).

With no radio gear or receiver batteries in place the plane is NOSE heavy.

GOOD. . .pulled the hatch, laid 2 fromeco 4800s. regulators and receivers and 3 standard servos on the aft mounting plate, put the hatch back on and lifted the plane again.

Deadnuts neutral.

COOL!!!!!!!!

Time to mount some batteries, regulators and receivers.

[KrisW]

Okay .. I want this to be TIDY, Clean, Efficient, and pleasant to look at, as well as functional.

First order of business. . . Receivers go at the back sides of the mounting plate. Wrapped in foam tape, with the servo location lettering exposed, a smear of Goop and ny-tie secure each receiver in place.

On the Fromeco regulatos there are 3 output leads for power out. Two get plugged into each receiver. These will directly power the receiver, one elevator servo, 1-2 rudder servos(depending on setup), the throttle on the left side (choke on the right if included), and one lead will go to the ailerons. The 3rd lead will go directly to the aileron/flap on each side of the plane. Since I'm custom making the wiring for this plane (parts coming in the mail) I can easily make everything to the length and spec I want it.

A note on the separate additional power lead directly off the regulator to the aileron. Being old school, and not using a power box, I want to keep the current flow off the receiver buss lands if possible. Running 3 5945's per wing will put additional current through this area, so by bypassing the receiver with a straight power lead off the regulator, I halve the amount of current the receiver must have passing through it. You only need 1 signal wire going to each wing, since the wiring has common ground, and common power, throughout the distribution system, so you can take voltage and ground from any common source and route it to the wings if you desire.

now. . Battery installation (after the regulators were mounted in a fashion similar to the receivers).

The mounting plates have these really LARGE holes in it. . coincidentally the Fromeco 4800ma packs will slide through these holes with about 1/16" to spare on each side .. .interesting. I grabbed at the chance to keep things closer together and reduce wiring and clutter.. .a 3" wide lite ply plate was installed under the front of the servo tray, attached to the bottom 3 stringers with thick CA. Then 2 1/4" spruce tri-stock pieces, 7" long, were glued in place to make a kind of "pocket" on the plate for the batteries to nestle in.

Each battery receives a layer of 1/8" foam tape on one side (bottom), and is then slid through the hole onto the mounting plate. A single drop of thick CA keeps things from shifting around much once it's in place (on the foam tape). The power wire is routed to the "Zero Loss" connector (I LOVE these things)and then a triangle shaped cover plate is screwed into place on top of the battery, holding it snugly, but because of the foam tape. . softly, in place.

Very easy, very quick, very secure. . and pretty cool, if I do say so myself.


I'll do a separate post on wiring the switches to the regulators and how the charge jacks will function.

[airborneSGT]

Elevators on mine are done. I have about 45 deg of throw with 5955's.
Wings will be done after I do some paperwork.
Engine will be mounted up around 5 or so!
Will take some pictures once the office clears out

[KrisW]

	Quote: Originally Posted by airborneSGT
	Elevators on mine are done. I have about 45 deg of throw with 5955's. Wings will be done after I do some paperwork. Engine will be mounted up around 5 or so! Will take some pictures once the office clears out

Sarge ! !!



Hurry. .hurry.. hurry. . .

[airborneSGT]

You having to mount your batteries mid ship? I will have one extra set of batteries for my Seiko servo. Not sure how this will effect my weight. I was really critical about my elevator setup and glued in my control horns with Hysol.

[KrisW]

	Quote: Originally Posted by airborneSGT
	You having to mount your batteries mid ship? I will have one extra set of batteries for my Seiko servo. Not sure how this will effect my weight. I was really critical about my elevator setup and glued in my control horns with Hysol.

Iplanned to use the rear wing tube location from the beginning, so everything I am doing is based on that. I seriously doubt I could manage to move enough weight forward to get the wing into the front position, especially using the full length tuned pipes.

[airborneSGT]

Aileron servos are in the outer most and middle servo slots. This is not 100% ideal now thinking about it....but it seems that by doing this each servo has about an equal amount of load placed on it. It works out to roughly 23" of aileron per servo. By mounting two servos most apart I would think it would put more stress on the servos.

Any thoughts??

[airborneSGT]

Thinking about it....I would think you would get better leverage putting the servos on the outer two bays. Regardless I ended up changing them to the outer most and inner most. Go with what works.

Servos and linkages done in wings and elevators.

[wildhare]

I recommend using the inner and outer servo bays. This gives the best support to the aileron (except for 3 servos which is optimum).

The manual was written when we had built-up wings, I never changed the CG spec when we went to foam wings. But you are correct, CG should be about on the wing tube.

TF

[airborneSGT]

I have not put in my rudder servo yet; the seiko will be much more powerful than a tray setup and I estimate about the same weight.

I did end up with the inner most and outer servos in the wings. So far ended up with about 45 deg of throw in the elevators and about 50deg in the ailerons. Hopefully this will be enough for 3D. I have still another hole I can move outward on my 1.5" arms.

I setup all my control horns so that they are at exactly 1" and my servo arms are at 1.25". This should give me a good ratio. Without even programming my aileron servos they are about dead on with no fighting except fo rmax. deflection.

I had to modify my 3W 150 slightly; I added a better throttle arm and also a better choke arm by using the small blue Hitec half arm. A little JB weld and a 4-40 nut and bolt ensure that both will stay put.

Depending on my schedule tommorow I should get it wrapped up. The hardware kit proved to be a very worthwhile investment.

[KrisW]

	Quote: Originally Posted by airborneSGT
	Thinking about it....I would think you would get better leverage putting the servos on the outer two bays. Regardless I ended up changing them to the outer most and inner most. Go with what works. Servos and linkages done in wings and elevators.

I think you are chasing your tail until you fall down on this one, dude.

The servos share the loading, no matter how flexible the ailerons are, though there will be a mild amount of independence if the surface is really flimsy. this is one reason I am not overly concerned with getting the end points EXACTLY right on aileron servos, because the inherent flexing of the surface and mounting pads on the servos will give you a little leeway under flight loads.

Everything flexes when the plane is flying, especially the wings and ailerons, since they are carrying the majority of the flying loads. As long as the servos use the same amount of arm travel, the fundamental loading of the servos themselves will be approximately equivalent. It's not like you had a true split surface, with each servo moving a discrete section of the aileron. They work in conjunction with eachother, so the loads are always equally shared.