F18/F22 BUILDS DAY 2

Didn't get a lot of work done on my F18 yesterday, decided while I had my work area set up to cut out foam, I would cut out the foam for my F22 so that it would be ready to go right after my F18 is done or I could even get some concurrent building going on.  Interesting that the raw foam for the F22 is 28 grams heavier than that of the F18, but I am not quite as concerned on the weight of my F22.

In the spirit of lightening things up on my F18, I have been weighing (literally and figuratively) some different options with respect to my components.  Since I am not going to be using vtails at all, I decided I will try to use one servo for my rudders.  This will allow me to use a 6 channel receiver over an 8 channel receiver which without talking about servo weights already saves me about 9 grams.  I normally use this receiver which I weighed at 18 grams.

http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=12339



By replacing it with this receiver, I save 9 grams, I weighed it at 9 grams on my scale

http://hobbyking.com/hobbyking/store/__12901__Hobby_King_2_4Ghz_Receiver_6Ch_V2.html



Also by using the HXT 900 9 gram plastic gear servos from Hobby King, which I weighed at 10 grams without servo horn, I will save 4 grams per servo, totalling another 20 gram saving.  I am not too worried about the strength difference as with this very light setup and motor, I shouldn't be abusing these servos too bad.

http://hobbyking.com/hobbyking/store/__662__HXT900_9g_1_6kg_12sec_Micro_Servo.html



The servos I have been really liking and using are the RC Timer TS 9018 MG servos which I weighed at 14 grams without servo horn (makes you wonder why they call them 9 gram servos... :) )

http://www.rctimer.com/index.php?gOo=goodspic.dwt&goodsid=642



So by being able to use 5 9gr plastic gear servos and the lighter receiver, I save myself 30 grams or 1 oz, which is pretty good.

I will also be experimenting with using Foam Tac on the inside of the score lines of the plane to reduce weight over tape, I experimented with a couple pieces of scrap foam, unfortunately I couldn't really compare weight on small 6 inch long pieces of foam as my scale wouldn't register the weight.  I am hoping over the entire plane it will save me a few grams through.

The technique I used was to draw a line on the foam on the opposite side of where I had the score cut so I could lay out a straight, very thin line of Foam Tac and then squeegee it with a scrap piece of foam.  It worked really well on the test, you can barely see the glue, but it holds the seam, similar to a hinge on a control surface, but much thinner.  Since I will be putting glue on the groove on the other side when the plane is built, I should still have a nice strong joint and plane with hopefully much less weight.

Here are a couple of pictures I took of what it looks like

I have to do a little research on how I will run the pushrods for the rudders, I will try to run the servo from the bottom with the double servo horn and then route the wires up through the fuselage.  This will allow me to put weight closer to CofG, and run the servo wire through to connect to the receiver.

I will post more today if I make any progress with either build.

Cheers,

Scott

PS - Lovin' that the NFL season has started, big football weekend this weekend!

About lunch time now, have made significant progress on my build, added a 4mm cf rod for wing support and 3mm cf tubes in each of the elevons for reinforcements, with glue added 17gr/0.6 oz to the build.

Also put a very thin bead of Foam Tac opposite all the score lines on the plane, then squeegeed it down to a very thin film and let dry for an hour, added zero weight to the plane, and all scores hinged perfectly!  Same amount of tape would have added 2 grams to the plane.

Also bevelled the leading edges of the vert stabs and elevators with sandpaper, bevelled the back of the prop slot and bevelled and made all the hinges on the ailerons, elevators and rudders and glued the bulkhead and nose support together, waiting for the glue to be good and dry now.

Also soldered up the connectors on my ESC, will be using a Turnigy Plush 30A ESC from HK, I love those ESCs, I have the programming card, so very easy to setup, but I will leave it with default settings for the Micro Jet Version 3 (MJV3) motor I will be using from HK.

http://hobbyking.com/hobbyking/store/__2164__TURNIGY_Plush_30amp_Speed_Controller.html



http://www.graysonhobby.com/catalog/ghmicrojetv3brushlessoutrunnermotor-p-425.html



I'll be back later with more info on the F18 build, hope to have a large portion of it complete today... :)

Cheers,

Scott

Finished building for today, got the plane all put together except for the electronics bay hatch and the vertical stabs.  Motor is installed, control horns installed on the elevons, all bevelling and sanding completed, the plane and parts now are sitting at 234 gr/8.25 oz, I estimate with everything else added including paint as long as I don't need to add to many servo wires, etc, I should be comfortably under 19 oz even with paint.

Paint scheme will be very simple and light, might even use some Sharpie marker to help out reduce the weight.

Been a challenge to build this light, but interesting to see how each step either adds or subtracts weight as I build.

More to follow tomorrow!

Cheers,

Scott