You are ingenious.  Why the side mount of the engine?  DOC Holliday

Bob R
THAT is a mighty fine installation on that Saito!  Looks like it came together really well for you.   

Looks like another T-Rex in the air by the weekend!

Back at it, now that the wing is in the fuselage I can make sure the engine down and side thrust are set correctly before finalizing the engine installation and cutouts.

Photo 1 shows my Robert Incidence meter on the wing with the airplane blocked up so the wing is at 0. Difficult to see because of the background clutter in the photo. The digital incidence meter on the engine is a Hobbico digital purchased from Horrizon. I bought the long extension they offer and cut a piece off just long enough to hold the meter mount and one end mount. This way I don't have the extra weight of a long rod hanging out in front.

I had drilled and taped the top motor mount for one engine hold down bolt leaving the other 3 unmarked. Once I had the engine down thrust set at 1.2 deg I marked the other 3 mounting locations. 1.2 deg is what My Latency ended up and saw no reason to go any less or more as the airplanes are real close to the same numbers. The engine mounting holes are somewhat larger than the 4-40 screws and even though it's centered at 1.2, I can adjust it from about 0 to 2 deg simply by loosening the mounting bolts and rotating the engine.

Next is setting, actually just checking the engine offset. Some time ago I grabbed a 14 inch piece of 1/2 X 1/4 spruce and drilled a hole in the middle. I stick this on the front of the engine and either check the angle from the fuselage sides or in this case (because the wing is symmetrical) I can simply measure to the wing. I like a little bit of offset, about 1 deg or so, the Saito has enough power it doesn't cost anything. Turns out the firewall ended up right at 0 so I will use a 1 deg Brodak wedge under the engine to give it 1 deg offset.

Now that I know exactly where the engine is going to be located I can check and finalize the cutout clearance, locate the needle valve hole in the top of the fuselage and locate the choke adjustment hole in the bottom cowl. Locating these holes was easy using the RC carb with the barrel and needle removed. With the engine installed I dropped a small piece of music wire down through the spray bar and poked a hole in the top block. Then I installed the cowl and poked a hole through it from the top using the same piece of music wire.

With the engine compartment complete I can now fuel proof everything. First I gave the engine and tank compartments a good coat of finish resin epoxy. After this was cured I lightly sanded as much as I could get to in the engine compartment and gave it a coat of black Rustolieum. Now waiting for it to dry....

On another subject, I've put together several ARF's and the first time I came to the instruction that says CUT away the covering I thought bad things can happen if you cut too deep.. With this in mind I devised a way to remove the covering in areas where it needs to be removed without taking a chance on cutting into the balsa underneath.

I ordered a Hobbico hot knife from I believe Tower, and cut the #11 blade it came with down to give me a sorta chisel point. I then dulled the sharp edge using fine sand paper and rounded the point. I happened to have a very long hose clamp I cut into 2 pieces. It has worked out well as it's stainless steel and bends easily but any piece of 3/8 wide thin sheet metal would work. I use the hose clamp pieces as a guide for the hot knife.

First position the piece as it will be installed and mark the cut line with a sharpie. I tape the guide down so it just covers the mark line which (hopfully) leaves just a tiny bit of covering in the glue joint. The photo shows the stab as I was removing the bottom covering. The left side is already cut and getting ready to cut the right. It also shows the piece of the hose clamp I used when I did the wing.

Well that's it for now, I'm am only covering the items I feel are unique to installing the 4 stroke and a couple items I feel make putting together ARF's better. If you have any questions I'll try my best to answer..

Thanks, found out shotgun boxes with the weight of the shells have many uses when building. I no longer bird hunt or trap shoot but the left over shells have been put to good use 

Putting the final touches on the engine installation..

Didn't really care for the idea of using Velcro to mount the tank, my experience with Velcro and fuel hasn't been that good. Decided to screw eyelets into the tank floor and use wireties to hold the tank. From past experience and measuring the Tank height the T-Rex tank floor is very close to positioning the tank at the proper height. I hit the eyelets with a dab of thin CA to lock them into the tank floor. Positioned the tank as far to the inside as I could get and still be able to put the screw eyes in. Offset the screw eyes to cant the rear of the tank out about 1/8 inch and tied it down.

I am using a modified RC carb per the write up I did on the Gluedobbers web site http://www.tulsacl.com/SaitoCarb.html which puts the fuel inlet right at the fuselage side. This requires the fuel feed tubing exit the tank compartment and be routed to the carb from the outside of the fuselage. Not elegant but it works. I used a 3 inch 1/4-20 nylon screw for the choke adjust in order to make it easily adjustable with the cowl on and added an exit tube for the crank case vent on the inboard side of the fuselage. This will spew a little oil but better than just dumping it inside the cowl.

Looks like you have a Stalker prop on there, what size is it ?

Looks like you have a Stalker prop on there, what size is it ?

Yep, it's a 13-5.5 that acts more like a 6.5, in fact I had repitched the one on the T-Rex to 6.5 when I first tried it on my Latency but it was too much (lap times at 8300 were 4.5 seconds) so went back to stock one. I repitched this one back down to stock and will see how it does on the T-Rex. I was lucky enough to have bought 3 of these props when Modusa was handling Stalkers. Not sure if Kaz still can get the same one or not. Didn't really care for it on the Stalker 61 but seems to work pretty good on a Saito 62.

Yep, it's a 13-5.5 that acts more like a 6.5, in fact I had repitched the one on the T-Rex to 6.5 when I first tried it on my Latency but it was too much (lap times at 8300 were 4.5 seconds) so went back to stock one. I repitched this one back down to stock and will see how it does on the T-Rex. I was lucky enough to have bought 3 of these props when Modusa was handling Stalkers. Not sure if Kaz still can get the same one or not. Didn't really care for it on the Stalker 61 but seems to work pretty good on a Saito 62.

I have a Stalker 61 with Stalker 12-6   3-blade.  Can see why your 61 didnt like the  13-5.  My 12-6 measures ~5.1 on pitch guage.  I need it be about 5.5, but I thought I remember reading somewhere that the Stalker props had a foam core and because of that should not be re-pitched.  Sounds like you have been successfull at re-pitching them.  What method do you use to heat the blades ??

One issue I had during the bench trimming process was I put a little too much pressure on the leadout guide trying to move the forward leadout and broke it out of the rib. Opened up the bottom covering at the wing tip and discovered the tip rib had broke. The leadout guide is glued to a light 1/16 rib and it doesn't take allot to break the rib. I cut rib doublers from 1/16 hard balsa and glued them to top and bottom of the leadout guide catching the rib caps and the spar. Hoping it will reinforce the rib enough that it won't be a problem in the future.

It might not be a bad idea to let Brodak know about this, in case they want/need to contact the manufacturer to instigate a change.  This may not be the only tweak needed in the future.  Time will tell as more are sold.  It is a beautiful plane, no doubt about it.

The TR goes where you point it.

I have just posted pics of my T-Rex ARC electric on the build thread in the electric forum. All  up weight WITH battery is 60 ounces!

bob branch