Stuart Chale

Next I mounted the stab, or really attached it as it is already aligned and mounted. The stab is held in by 2, 2.5mm cap screws which thread in from the bottom of the left stab into the carbon fiber rods. The rods have a bit of wood in their ends to accept the threads. I drilled and threaded the holes, then hardened the threads with ca, and ran the tap through one more time. The plane comes with a roll of self stick foam to use as a vibration barrier between the fuse and wing and stab. I cut it into strips and applied it to each stab. The foam was too firm and could not be compressed enough to get the screws started however. So I went back to my standard method of using a thin bead of silicone rubber which molds to the fusalage shape.
First step is to apply a piece of polyethylene plastic (from a bag) to the fuse so the silicone does not stick to it. A thin bead of silicone is applied to the edge of the stab and it is pushed in place. After 10 minutes or so, just enough time for the silicone to start to set, the edges are tooled with a rounded piece of wood. A toothpick or a small popsicle stick shape works. The edge is sharpened but kept rounded and run along the edge of the stab keeping the "point" as close to the stab as possible. Excess silicone is forced up and away from the stab and stays on the polyethylene sheet. After a few hours the stab can be removed and the plastic sheet peeled away to allow the silicone to fully cure. This worked well and the final fit of the stab is tight with no play.

Stuart

Stuart Chale

The next thing I started on was the motor mount. I decided to make the plate that the front of the motor screws into out of .125 carbon fiber plate. The hacker motor comes with two fiberglass rings. One appears to be a spacer and the second could be used as a mounting bracket although I think the design with wider spread ears makes more sense to me, so that is what I set out to make.

I started with a square of CF plate and drilled a center 1 inch hole which fits the Hacker very well. I think the actual diameter of the motor mounting flange is just under 1 inch. In order to drill the 8 holes for the mounting screws I tack glued the hacker supplied mounting plate to my plate using a 1 inch wooded dowl for alignment. A 3 mm drill or number 32 drill bit works well. Using a drill press the holes were easily placed.

Next was the layout of the piece I was trying to make. I started with a square which was 54 mm on a side. This gave me the approximate 2 3/4 inch measurment across the diagnal that I was looking for. I drew the outline with a circle tmplate and the 1/2 inch nylon stand-offs that will be used to mount the bracket to the nose ring plate. The spacing between mounting holes through the stand-offs is about 2 5/16".

The final shape was cut on a jig saw and a finished off on a drum sander.

In order to drill the plate mounting holes in the corners, I tack glued the nylon stand-offs in position and used them as a drill guide. The nylon standoffs are 1 inch long and will need to be cut to size once the nose ring is in place.

I actually made two mounting plates. The first was the smallest I could make with the nylon stand-offs just touching the spacer ring. I decided togo a little wider on the design for more support.

Stuart Chale

For the nose ring I made several templates, first out of cardboard then 1/8" plywwod before making the 1/8" carbon fiber plate. I cut out the plate with a hole saw to start and adjusted to fit with a drum sander. The stuff sands a lot easier than it cuts with the jig saw. For the center cut out I just happened to have a 1.5" diamond drill bit that I have used to drill holes in a glass fish tanks. That cut right through the CF plate quite easily.

Test fitting the motor showed that the stand-offs needed to be exactly 3/8 " with a 1/16" spacing between the nose of the fuse and the spinner backplate. I cut out 4 pieces of 3/8" ply to act as temporary spacers between the mount and the nose ring. Countersunk 6/32 screws are used to mount the mount to the nosering. After everything was fit a bit more of the inner carbon material was sanded away to its final shape. Instead of locking nuts, small 6/32 blind nuts were glued to the back of the motor mount after their prongs were cut away. The smaller variety is short enough to fit in a 1/8" thick piece of material.

Stuart Chale

The nose ring was glued in with Hysol 9462 a Loctite product sold by several vendors including BVM Jets under the name of Aeropoxy. I had trouble with the glue hardening which I determined to be due to inadequate mixing. This slowed me down by a few days waiting for things to harden and then having to redo them The nose ring was held in place by the mounted motor.
The prop pulled the mount tight so that the plywood spacer ring imparted enough friction to hold everything in place until the glue hardened. After drying an additional bead of the epoxy was applied around the perimeter of the nose ring.

The nylon stand-offs were cut to 3/8" and worked well. The weight of the nose ring without glue was 11.2 gms. The motor mount pieces including the fiberglass ring and mounting screws supplied with the hacker mount was 25.9 gms or .915 oz. The mount alone with out the hacker parts is 20.3 gms or .715 oz.

Stuart Chale

While waiting for the glue to harden I started making the template for the rear support. This area is a compound shape. There are plenty of ways to make a template but I chose to build it up out of several pieces of shaped balsa. That way you are only fitting a small section at a time and gluing it to the rest. Not real pretty but gets the job done.

Stuart Chale

The rear mount was made from 1/8" end grain balsa fiberglasss laminate. (one of my favorite composite materials) The rear support was made from the same material and lined with a piece of fuel tubing. A hole of 1.825 inches is about right with the fuel tubing for a snug fit on the rear of the motor. They are held together with # 2 button head servo type screws. Small pieces ot gold Nyrod are used to retain the screws as in the servo mounts.

The rear former and rear support with fuel tubing and screws weigh 19 gms or .7 oz. Of course add a little weight to glue them in place.

Stuart Chale

For the tail wheel I chose the MK product for simplicity. It is fairly light and easy to install. The pinnacle has the horizontal stab incidence adjustment access hole on the bottom of the fuse in this area. The front hole in the picture is this access point. Just behind this point the pinnacle has a hardwood block built into the fuse to support the tail wheel. I placed the front mounting hole of the tail wheel over this hole and drilled an additional hole for mounting closer to the tail wheel pivot. The main hole for the tail wheel is a 1/4 inch hole for the pivot "block". The pinnacle has a hardwood block in this area built into the fuse. The tailwheel is simply installed with 2 screws and a pin in the rudder.

Stuart Chale

The next step is the one I have been puting off. The elevator servo and linkage. The position of the rear cutouts for the pushrod is critical for a straight run to the elevator horns. It also means cutting into the fuse and hopefully not messing things up I first want to check how much leeway I may have for placement of the servo and tray in regards to balance point. I want to see if I need weight as far foward as possible or will placing it back by the rudder servo be OK. I also want to get an idea of how much weight I can get away with for the battery packs. The Thunder Power packs are still the lightest available but there are several newer packs with higher C ratings that are a bit heavier now available. Falcon packs even come with a 6 month warranty. The Flightpower web site is also announcing a 30C battery. So I made up a couple of mock TP batteries to get a better idea of where I am at present in regards to weight and balance. Balsa boxes filled with pennies did the trick

Stuart

Stuart Chale

I finally had no excuse to delay starting the elevator pushrod instalation. I have been very weary about cutting into the fusalage for the pushrod exit and have been doing everything else I could before tackling this.

Although I know that people have had minimal problems with the DEPS system from Central Hobbies or something similar I have a mental block about using the .07 carbon fiber rods. I had decided to use .125 carbon tubes instead. They are a bit stiffer and should require less supporting structure. The fuse exit structure was an issue however and what I finally used was different from what I planned on from the beginning.

I decided to mount the pushrod before mounting the servo or horns. That way the horns could be mounted at the proper distance from the fuse rather than trying to line up the pushrods with a pre-existing horn. The pushrod could also be made parellel to the stab and the servo mounted at the proper height in the fuse.

I started by marking the center line of the stabs and measuring down front and back the distance to where ther horn connection would be. That way the pushrod is parallel to the stab. By continuing this line foward I have the pushrod exit line and height at the sevo arm connection as well.

Using a straight edge from the center of the servo area as pictured in Troy Newman's DEPS installation article I found the the pushrod should exit right at the rear former which I also marked. (not shown in picture)

Stuart Chale

Initially I had planned on using a teflon tube as the exit gude for the pushrods. Unfortunately the teflon tubing that I bought is thick walled ( 1/16" ) and came in a coil. Although it is easily straightened it does not hold perfectly straight and binds the pushrod when used in a several inch length. I had planned on inserting the teflon tube through a piece of light balsa which could be glued to the inside of the fuse. After making a slot for this and trial fitting I decided it wasn't allowing easy enough passage of the pushrod. I also had a piece of larger carbon tube with a .125" opening that could act as a guide but the opening I had already cut was a bit larger than that and would need filling. Something I wanted to avoid with a painted fuse. I found a fiberglass pushrod set, probably Dave Brown that fit the slot perfectly. I was able to use a 1/2" piece of the teflon tubing in each end to act as guides. The diameter of the teflon had to be reduced to fit the fiberglass tube. A bit of sand paper while spinning the teflon in a drill did the trick. I haven't measured it but the exit guide is probably about 3 o 4 inches in length. After matching the opposite side the exit guides were glued in with 5 minute epoxy. I still need to mount the horns and servo. One or two additional supports will be added between the exit guide and the servo.

Stuart

Stuart Chale

I finally had some time to finish the elvator pushrod setup.
Only one center support was needed. There is about 26 inches between the servo arm and the inside support at the fuse exit. The support was placed midway between. I decided that one support was enough when I was unable to get the pushrtod to flex with manual pressure on one end. The support was made from a piece of 1/8" end grain balsa fiberglass laminate. The guides were made from small pieces of teflon tubing with 1/8" grooves cut in the center at a slight angle to match the pushrod angle (2 degrees or so). This was my reason for using the thick walled teflon tubing. The support was made in 2 halves to entrap the groove of the teflon bearing. The piece of teflon could be rotated to match the angle for the smoothest movement. After I was happpy with its position it was glued in place. To help position the central support I made a temporary foward support This was placed before the central support in direct line with the pushrods and elevator horns.

Once the central support was in, I made the elevator servo tray. This was made from carbon fiber nomex 1/8" plate. The servo was attached with BVM right angle servo mounts and positioned before gluing the plate in place. Lightening holes were cut as well. I choose to use dual ball link attachment at the servo arm instead of combining the pushrods into one. This way the pushrods can still be removed from the plane if ever needed by just removing the ball links from them.

The pushrods with ends and guides added 27 gms to the plane. The elevator servo tray an additional 7 gms.

Stuart

Stuart Chale

It is probably a good thing that I bought an "ARF". If I had to build a plane from plans or a kit right now it would probably take me a year based on the amount of free time I have had to complete this project

Today I finished up the cutouts for cooling air movement. The front top of the fuse already has a scoop built into it. I added cutouts in the cheek cowls and in the belly for air exit. This is definitely something that I feel should be done by the manufacturer on any prepainted plane. (especially at Oxai's prices.) Cutting into a prepainted fuse leaves raw balsa edges and small paint chips at the edge of the cutout. Unless the edges are sealed it is likely that the paint will probably chip as well. Add to this that no matching paint is available from Oxai makes this more of a PIA.

I made templates for the cutouts out of a plastic tracing paper. It is partially see thru which allows for easy placement. The templates were cut out and taped to the fuselage. Material was sanded away up to the template line using a Dremel and hand tools. The main part of the fuselage is a balsa fiberglass sandwich so raw balsa is left exposed in the belly cutout.

The only major item left is the battery tray. Hopefully I can get to this tomorrow and weigh the plane to see how much weight I can afford for batteries. TP 5300's will be no problem as far as weight goes. Falcon's batteries will probably put me just over the limit and some of the other new cells will definitely be too much. I haven't ordered any yet as I am hoping I have a choice based on weight. I have been trying to cut a few grams were ever I can but I do not think it will be enough for anything but the TP 5300's. I'll know shortly.

Stuart

Stuart Chale

Time to finish the build pictures:

To finish off the plane the battery tray was next. The tray is made from carbon fiber nomex composite. Balsa rails were added to the inside of the fuse to aid in alignment and increase gluing surface area.

The tray also serves as the mount for the speed controller. Small round spacers were added to the bottom of the tray to prevent the speed controller mounting screws from protruding through the top of the tray. Screws are mounted in yellow nyrod as in other areas of the plane.

The 2 slots in the tray are openenings for the velcro strap. The second strap is tied to the landing gear plate. Two .125 carbon tubes provide the anchor points.

Stuart Chale

For Batteries I chose the Falcon F3A cells. They come with a 6 month warranty but only time will tell if they provide more cycles than the leading brand. Price is about the same. The penalty is 5 ounces over TP cells. With TP cells the E Pinnacle will make weight easily even if you are not careful about weight savings. The extra 5 ounces caused me to re-think a few things regarding weight. After making the mock-up batteries it was apparent that my current weight would be over 5 kg. I changes steel for aluminum wherever I could. I changed the wheel axels from 8 x 32 steel bolts to NMP aluminum axels. The 4 mm landing gear bolts and nuts were changed to aluminum. These two items saved about 1 ounce by themselves. Small areas of unneeded wing root and stab root were removed for savings of a few more grams. All extensions were changed for the minimun length that fit. Extra wire like the charging lead from the switch harness was removed. As I had switched to a 900 mah TP 2 cell Li poly for the Rx battery I would not be charging it in the plane anyway. The main battery pack leads were shortened as much as possible and the 2 packs were wired together to be charged as a 10 cell pack. Keeping them seperate would have added another connector. The two packs are glued together with several pieces of 1/4" sq balsa to act as spacers. Total weight of the 2 packs with Deans connectors is 1263 gms.

After figuring out the appropriate position of the packs for balance, 2 alignment strips are glued to the bottom of each pack to lock them in place around the landing gear mount. Batteries are held in place with velcro cinch straps, shortened and cut thinner to fit and save weight. The cinch style strips are the easiest to fasten.

The receiver and receiver battery are held to the center bulkhead with self stick velcro.

Stuart Chale

Finished pictures:

Adamg-RCU

You can save another 23g by using a TP 2s480 RX pack for competition flights. In my experience, and that of everyone I've spoken with, has been that a P07 flight uses 40-50mAh from a plane with full digital servos and 6v regulator.

Stuart Chale

This is my first electric pattern project and the first time I have even seen this size motor run. I ran it up in my foyer in order to get some RPM and current numbers. All I can say is that I am very impressed with the power of that fan up front. Window curtains were blowing all over the place 20 feet away. Hopefully the weather will clear sometime this week so I can make the first flights.

Final weight? Well even with the weight savings listed above; with the APC 22 x 12 E prop mounted I am over by about 10 or 15 grams. With the 20 x 15 prop I am under the limit. Changing to the smaller prop also moves the CG by about 1/4 inch

I have a few ideas for additional weight savings for the final few grams. If I can find it or modify something existing, changing the spinner adaptor to aluminum would save a bit. Right now I have the double jam nut for a YS 120 I believe. The screw holding the spinner cone can also be changed to aluminum.
The 4, 6 X 32 countersunk screws holding the motor in place could be changed preferrably to titanium but aluminum may be strong enough. The 2 elevator control horns (MK) are held in place by 3mm x 30 steel socket head cap screws. If available, aluminum there would save another 4 or 5 grams. All of this will surely not effect flight characteristics at all but I like to play by the rules.

Although I have built some very light pattern planes in the past, it is much easier to do when you build form a kit of from scratch. Your possibilities to reduce weight in an ARF are available but limited. All in all a very interestng learning experience. Weight savings were measured in gms and just kept adding up.

To reiterate though the plane will make weight easily when using TP 5300 cells which are pretty much the standard.

First flight report soon!

I hope the thread will prove useful. I know I learned a lot from similar posted build threads.

Stuart

Stuart Chale

Thanks AdamG. I really hadn't thought of going to an even smaller battery pack. I am sure digital servos pull more current but then again 15 years ago we were running 5-600 mah nicad receiver packs and flying 5 flights.
Thanks
Stuart

Adamg-RCU

I'm sure in a snap they are pulling something like 4A total, but a 480mAH pack can put out 10A briefly. It covers your burst and capacity needs safely - just needs to be recharged more often than a 910mAh.

Definitely put some flights on your plane with the 910 pack, then use a charger with capacity display to verify that your system is using similar capacity per flight.

KeithB

My Feedback: (1)

Stuart, I'd be concerned about the way you mounted your battery and RX because I've had several experiences where the self sticking Velcro has come loose after being in the hot sun for a while. I secured mine down with a wrap of Velcro, and in the case of the battery I blocked it from possibly slipping out by using a really light piece of 1/4" balsa. Under these I put some soft neoprene as a shock-absorbing device, but I don't know if that's necessary.

Stuart Chale

I may change the velcro to a wrap or add a wrap for security until I am sure that the self stick stuff will not come off. Right now it takes a lot of twisting to get them off. I have to be careful that I do not break the bulkhead when removing them.
Thanks
Stuart