Painting the cross members that will show under the hatch seemed to be an important detail to making this plane look good. Now the lower cross members fade into the fuse as if they belong there.

Getting the servos nested in their holes was a small task and a revealing one. Tom mentions in his manual to check all servo mounting plates because they are a weak spot in the manufacturing process...he's right. I had one of the elevator servo mounting plates come completely out while I was trimming it...only a small dab of glue was on it. The plates are not an integral part of the airframe. Special care needs to be taken to make sure they are glued in and can handle the rigors of fast flight. Those large surfaces see the most force when flying smooth aerobatics at moderate to high aircraft speed.

I wicked thin CA around the other servo mount and then put a bead of medium around the edge to make a small fillet. I glued the servo mount back in with slow thick CA, wicked thin around the edges and then put a fillet around the outside to make sure it stays in.

Mine did the same with the same fix except I globbed some 15 min epoxy on mine which added about 2 oz to the tail. On the next one ill be using the ca fix that you have used. It sounds to be a lot less weight than my slap-dash fix.

Each of the holes in the fuselage was neatened up by taking a soldering iron and melting the edge of the covering down while making sure the hole was round. A handy way to get the holes sealed around the edges, I might add.

Now that the tail of the plane is pretty much done, I went ahead and mounted the elevator servos. I made sure to take the servo out after the holes were drilled and hardened the servo screw holes with thin CA. I wouldn't want a screw to pull out in flight! I securely soldered a 24" twisted heavy duty 18 gauge wire extension to the servo lead. Each wire was individually insulated with heat shrink tubing and then all three wires were pulled together with a final piece of heat shrink tubing. This ensures the leads can't pull apart and that I have the best connection possible between the extension and the servo wire...as close to zero loss as possible.

Flatlandmike:

I thought of using epoxy until the weight thing sparked the thought of CA. Thick CA is supposed to be just as strong as epoxy, as long as the parts have a good fit.

To seal the hinge gap I used some transparent clear plastic film I found in the back of the hobby shop...it was marked as "hinge gap sealer" and sold in two foot by two foot sheets for 98 cents. I thought I would give it a whirl. I bought two packages, so, worst case, I would be out $2. I cut the sealing film to fit the beveled surfaces that were exposed when I opened up the gap by fully deflecting the control surface.

A one inch by eleven (plus a little) inch piece was used on the top and bottom of each elevator gap to make a nicely sealed hinge area. To keep the hinges from crinkling the film I cut small holes where each hinge was so the film would stay folded right down in the crevice as the beveled surfaces came together.

Now I won't have to worry as much about elevator flutter or control effectiveness, it is all taken care of (as long as that sealing film stays stuck).

Installing the surface control horns is a rather arduous task, just like most of the finishing jobs with any aircraft. I chose to leave the top covering in tact and drill the hole, then screw in the bolt to just under the covering. I used a 1/8 inch drill bit, not the 9/64 that Tom's instructions talk about, and took special care to clean out the sawdust every eighth inch or so as I was drilling the hole. By grinding the tip of the bolts to a 45 degree angle about half the diameter the bolt could freely cut threads in the hardwood. I screwed in the bolt then took it out to strengthen the threads in the hardwood block with thin CA.

I screwed the bolt back in, measured 1-1/4" from the center of the control surface and added 3/16" before cutting the bolt off. I am going to use 1-1/4" servo arms and I want a one-to-one ratio from the servo arm to the control horn. This gives me the needed clearance for the pushrod as the surface deflects on high (3D) rates, as well as the full torque rating from my DS 8611 servos. The 3/16" was added to compensate for the attachment nut for the pushrod that threads down onto the control horn. I want 1-1/4" from the center of the control surface to the center of the pushrod, not the top of the pushrod attachment nut.

To keep the hot piece of metal from burning my covering, I put some blue masking tape on around close by where I would be cutting. This prevented the sparks from burning the covering while I cut and kept the area clean too. It pealed right off when I was finished and went on the other side for cutting.

Perfect geometry is the key to perfectly matched elevator halves. I don't want to fight any crazy mixing, I've got my own learning curve to battle against.

Light, plenty of power, more than enough current and reliable as is necessary...nothing complicated here.

Duralite 6.0V Failsafe Switched Regulators - ignition, receiver, receiver
Never had a problem with these switched regulators. Duralite service is excellent. The two RX regs are matched at exactly 6.05V (read when attached to RX). Six volts is on the upper end of the range for DA, but runs the engine just fine and doesn't dissipate too much energy to heat.

TBM 2350mah Lithium Ion Batteries (3)
To slice right through the debate, it works. Great flying times...10 fifteen minute flights - easy on this battery setup, perfect for a long weekend of flying! Anything more and I would add weight. Each battery is only TWO cells...nice.

JR 945S PCM Dual Conversion RX
I decided if I was going to run only one receiver I would run the best that money could buy. Maybe that will be Spektrum next year, but right now it is dual conversion PCM.

DS 8611 servos for all flying surfaces
Why not supply the flying surfaces with as much torque as possible in a standard sized servo case? Ok, the case is a hare larger, but hey, it was worth the little bit of trimming I had to do. So far the metal gear JR digital servos have performed flawlessly over more than one hundred flights.

Hitec 5245 MG on throttle
Metal gears keep vibration issues from being a problem by stripping the gears on my throttle servo, digital gives me the same idle as well as the same throttle position throughout the range of my input and the mini size gives me plenty of options during mounting.

Hitec 225 MG on choke
The same size as the throttle servo but digital isn't needed on this little guy, but I stuck with the metal gears to combat that vibration. With well over 55 oz/in at 6V this little servo should be able to handle the choke actuation without a problem in the event that my throttle gets stuck and I need to shut down the motor in an emergency.

What better than some nice black self wrapping hook and loop fasteners to hold everything down over silicone rubber padding. I chose the 1/2" thick foam so I could smash it down a bit while tightening the fasteners and still have a 1/4" or so to isolate the electronics from any vibes that might make it back to the radio compartment.

As for the layout, we'll see if I have to move those batteries back, but for now they are in a fairly neutral place. The regulators were the furthest away from the switch mounting holes that Tom so graciously had drilled for us right behind the trailing edge of the wing. Everything should mount up with few flailing wires. Any loose wires I will secure with JTec fasteners or hot glue!

My receiver antenna is going to go straight down and out the fuselage, run along the bottom of the fuse and be held mildly taut with a properly sized rubber band or two. Notice: I taped in my RX crystal...HIGHLY RECOMMENDED!

Looks good. Looking forward to final thoughts.

Well, final thoughts will come, but there is much more to come before we'll get there.

Yet to be completed:

Spinner back plate drilled
Spinner cut for prop
Incidences checked and corrected if necessary
Enclose canister tunnel, seal wood inside tunnel
Canister and header mounted
Engine box finished, battery and ignition mounted
Servo extensions secured
Balance determined after everything else is done, then rudder servo mounted in appropriate place

Here we go again!

I cheated here...I had the old firewall. I carefully measured my previous Wild Hare to mark the throttle and choke pushrod access hole. To measure this passageway I initially made a smaller hole and worked outward little by little in the direction I needed to go for the pushrods to work freely. You can see that the cutout is generous, but even after over 100 flights the firewall didn't show any signs of cracking or flexing.

I made sure to put the DA-50R inside a protected box or bag while I was cutting and sanding since I didn't seal off the carburetor and exhaust. The last thing I wanted was to get dust inside a model motor that cost as much as a rebuilt Chevy shortblock V8.

Drilling the spinner back plate was a little tedious. My drill jig ( www.troybuiltmodels.com/Propeller.htm ) was a little tight fitting through the center hole in the Esprit spinner back plate and I didn't want to enlarge the hole. That center hole is what keeps the spinner centered on the crankshaft...the bolts just hold everything together.

The most important part of correctly drilling the back plate and prop is making sure one of the blades of the prop is at the 1 o'clock position with the piston coming up on compression. This will be the key to safely starting your gas motor without the fear of it backfiring or popping back on your hand. I don't use a glove and have never once had a problem with the prop doing anything but what I want it to. (Even my wife is comfortable hand propping it.) Starting the flipping at the 1 o'clock position and right before the compression stroke allows my hand to follow through naturally and with good force.

I used a drill press to make sure I got the holes drilled vertically square with the back plate. After lining up each hole with the drill jig and carefully drilling the hole, I placed a bolt in the hole to make double sure it stayed centered.

After drilling the back plate, I centered the prop between the splines that stick up to hold the spinner on and marked the prop. Using the drill jig I then drilled the prop from both sides.

This new line of Wild Hare R/C propellers looks promising![8D] I chose to try the new 22x8 WH prop for the break-in of my DA-50R. The root of each prop blade is slightly wider than the NX prop of the same size. The prop is a full 22" in length and weighs 4.3 ounces (122 grams). The clear coat is so shiny that I had trouble taking pictures of it...now all we need is a bunny on the blades!

Now that the firewall is cut for the pushrods and the hole for the fuel line to the carburetor, I went ahead and sealed the wood with thinned 5 min epoxy. Rubbing alcohol works great to thin out some epoxy so it can be brushed on with a throw away flux brush. I found that sometimes a gasoline engine will spray a little fuel out the intake of the carburetor when it is running a little rich and I didn't want my firewall soaking up that fuel during the engine break-in period when I will undoubtedly be starting the engine rich before it has a chance to be leaned out any.

For the final installation of the DA-50 I applied Blue (Medium) Loctite to the bolts to ensure vibration wouldn't loosen the standoffs. I chose to use hardened bolts with a hex head to fasten the motor to the firewall. The allen head bolts were too hard to tighten enough for my liking, plus the hex head bolts have a wider footprint to apply even pressure to the fender washers I put on them. The key, I think, is to apply a generous amount of force but spread it out a little, that way the firewall will be as strong as can be for those Hare-y maneuvers and abuse I'll be sure to put the plane through (intentionally and by accident).

To get these bolts tight I used a rachet, a knuckle, two extensions and a 7/16" socket. The top bolts were tough to get to and required the knuckle. I am confident that the bolts are tight and will hold!

Time to get the spinner a little closer to being finished. Cutting the spinner to clear the prop can be a little intimidating so I read the directions on the Esprit Model website to gain a little understanding.

http://file.espritmodel.com/document...nner_cutt.html

It was easy to get both cutouts the same using the cardboard pattern technique. To make sure the pattern was placed exactly the same on both sides I drilled one hole in the carboard so it could be lined up on the spinner with one bolt through it for that perfect placement.

I had to leave a little extra room in some places around the prop to make sure I could get the spinner on and off, but there was no unsightly large gaps that sometimes are a byproduct of a precut spinner. Starting with the cutting wheel on a dremmel I made the initial rough cut. Fine tuning with a sanding drum on the dremmel, then a cutting bit for the corners I was able to make quick work of the cutouts. A little final sanding after a trial fit and I was done.

Look for coverage on the painting of the spinner Cub Yellow to match the yellow stripes on the Wild Hare Extra 300's fuselage in a future post. I love fiberglass spinners!

'Cause it had to be done, I went ahead and put the switch mount and charge jacks into their places. I chose to go ahead and use part of the precut switch cutouts that Tom designed into the fuselage on the 84" Extra. Each battery has its own regulated switch mounted with Dubro switch/charge jacks behind the wing and the ignition regulated switch is in front on the pilot's right just behind the motorbox and cowling.

All I had to do was cut out the covering where the mount would be protruding into the fuselage on one side of the hole, then drill a hole for the switch slider. I hardened the hole and surrounding balsa with thin CA then installed my switch/mount assembly. The "OFF" position is "IN" so if I (or someone else) were to bump the switch in transit it will stay "OFF" instead of turning on and depleting my battery's charge...very bad for Li-Ion batteries to go below their minimum voltage.

Well, I'd better stop posting and get back to work...I want to fly this baby soon! The weather is PERFECT out here in CA...75F and CALM! That will change soon...

Here's the pen I've used for "painting" the wood black. It is a paint pen I got from Michael's craft store. Works like a charm.

The hatch has a tendency to vibrate a little during certain RPMs and this causes the screws that secure it to back out on occasion. Tom suggests trying some nylon 8-32 bolts to prevent that from happening...I'll try anything once, so I gave it a whirl. [&:]

I popped off the blind nuts on the inside of the hatch hold-down tabs, then threaded them with an 8-32 tap. I had to drill out the fuselage sides to 5/32" to accomodate the nylon bolts. After everything was trial fit I applied thin CA to all the newly cut wood to make sure everything would be solid. The threads were firm but not too tight after applying the thin CA and the fuselage sides stiffened up a bit...I wouldn't want any vibes to elongate those holes!

I trimmed the nylon bolts down to 7/8" which was enough to let them protrude into the fuse by about 1/4" to give me a warm fuzzy. To make those nylon bolts look a little more at home I colored the heads of them black with the paint pen...we'll see if that lasts. Ideally I need to get some 8-32 black plastic bolts with a hex head for ease of installation and removal at the field. The flat heads just aren't very convenient. [&o]

It was time to install the battery and ignition to the sides of the motor box. I am getting ready to route wires, install the throttle and choke servos, and finalize the front end of the plane before I get the canister installation under way, so this was the first step. I like to see my parts bins empty out, it means were closer to being airborne!

I simply held up the battery and ignition module where I thought they should be located and marked where the holes for the Velcro should be drilled. I chose self wrapping Velcro over zip ties for a few reasons:

1. Vibration -- zip ties are hard and easily transfer vibration to whatever they are touching
2. Ease of installation -- the self wrapping Velcro is simple to route through the holes and pull the foam in for a good solid fit
3. Ease of removal -- the Velcro can be easily removed to service the battery or the ignition module
4. Good looks -- red Velcro matches the red trim on the DA-50R, so it was a natural choice
5. Flexibility -- Velcro is somewhat flexible, unlike a zip tie, and won't just snap...I'll be able to see the wear starting and replace the strap as necessary

Those nice straps can be found at Home Depot. I found black straps at Walmart.

The fuel dot that comes in the Wild Hare hardware kit is nothing spectacular, but that is the point. It is fairly subdued and I could paint it if I wanted to. It screws nicely into the wood and will stay there eternally with just a little medium CA. I applied some thin CA around the inside of the cutout after the fuel dot was in and glued with medium, just to harden the wood around. Pulling and pushing on the side of a plane does add a bit of stress, so I wanted to make sure the plywood could take the abuse.

There are three ways to make extreme duty pushrods that I know of.

1. Use Central Hobbies titanium rod ends and carbon fiber tubing. Measure everything, cut the CF to length, clean everything with rubbing alcohol, glue the ends in with JB Weld. This is my favorite home-made pushrod.

2. Use the all-thread in Tom's hardware kit along with the CF rod for strength. Measure the rod with the ends attached to the control surface and the servo arm to get the overall length. Cut the all-thread. Cut the CF tube short enough that you can get your ball links threaded all the way on with out hitting the nylon nuts, then assemble all the parts and you have a strong pushrod.

3. Use Troy Built Models steel rod ends and carbon fiber tubing. Measure, cut the CF, clean everything with rubbing alcohol, then JB weld the metal rod ends on. These are black and blend in the most.

Of course, the BEST solution is if you can find the right length Hanger 9 Titanium Pro Links and use those for the finest adjustments (less than half a turn) and suburb looks! Measure from center hole to center hole (center of pushrod connector screw on flying surface ball link to center of hole in servo arm) to get the length and pick the one that falls in the middle of the range required.

The key is this: If you're going to JB weld something, clean the CF dust off first with rubbing alcohol! That way the pushrod will NEVER pull loose. I've tested mine by pulling on one with all my might...it didn't budge.

By way of necessity I'll be using the H9 Titanium Pro Links on the elevators, Tom's hardware pushrods on the ailerons, and TBM's push rod ends on the throttle and choke. What variety![&:]

I chose to use the hole on my servo arm that corresponded to one inch away from the center of the screw hole and used 1-1/4" from the center of the aileron to the center of the attachment bolt to give the servos a little mechanical advantage. I still get the recommended throws from the manual...BTW 12 degrees up and down on the elevator is great for low rate ops, plus takeoff and landing.

Checking the incidences of the wings and horizontal stabs with reference to the "zero degree line" gives me peace of mind and could prevent a great deal of heart-ache down the road. If any of the incidences are off I can correct them before they have a chance to give me undesireable flight characteristics. Beg and borrow an incidence meter, or buy one if your club doesn't have a "community" use meter...I finally had to buy one because no one I knew had one.

First I chose a reference line for the "zero degree line." The only logical choice was the hatch area that was straight and flat. I set my incidence meter on the hatch area while it was detached from the spanner, and along the side to get the truest level reference possible. I leveled this zero degree line using the level and degree meter on the Robart Incidence meter and books under the tailwheel. I checked between each flying surface I measured to see if the hatch area was still level. To reach all the way across the chord of these larger planes I had to buy a longer spanner. Home Depot came through with a piece of nice aluminum the same thickness and width as the original spanner. The new piece came in a four foot section and cost me less than $5, as opposed to buying the Robard brand name replacement for $20 or so.

My results came out with the wings at zero degrees as well as both the horizontal stabilizers. The best time to check the horizontal stabs is BEFORE glueing in the hinges so a true incidence check can be done. I'll make reference to this post near the beginning so people seeing the thread for the first time won't omit this important step!

Canister time![8D] Yep, all of that has to go in "there."

After stuffing the canister inside the tunnel I knew I was going to have to do some work to figure out how to make it work well. My goal is to create a method, complete with dimensions and templates, that can be used over and over to make this canister install quick and painless, so it is going to be slow and arduous for me. I like a challenge!

Well, back to work, it ain't buildin' itself!

I'm holding off sheeting the inside for the sake of trial fitting everything first. The balsa for the top of the tunnel will definitely go on the top, I need all the room I can get! As you can see I needed to trim the bottom crossmembers where the landing gear plate is. Trimming these will allow ample room for the canister to rest completely inside the ring on the rubber bumpers.

The aircraft is not wide enough to get the exhaust exit tube down through a hole in the fuselage. I had to cut out a elongated section for the exit pipe to rotate down through. I could have cut the fuselage down at the center where the cowl ring mates up, but I didn't want to sacrifice the integrity of the fuse front.

Desert Aircraft warned not to cut the header pipe shorter than 10-1/2" or it might affect the performance of their engine. That limited me as far as being able to pull the canister forward and have it exit through the cowling. I did not want to cut the cowl ring either, Tom highly recommends leaving that in tact.

Desert Aircraft advised me not to cut the header pipe shorter than 10-1/2 inches in length for the DA-50R. I measured and cut off only 1-1/8 inches, which allowed me to have a pipe that was 11-1/4 inches long...whew!

It is worth going over the dimensions of the canister mounting piece to make any subsequent canister mounting experience MUCH quicker and easier. It took me at least an hour to get that canister mounting ring to fit properly, line up the canister so it is in the proper position to accept the header without stressing the coupler. At least it fits nicely so the glue will hold when I do the final assembly.

Now to shoehorn everything in to see how it fits! DA also said not to cut the stinger pipe if possible, but if I HAD to cut it that hacking off an inch wouldn't make that much difference. I can't wait to hear this baby running and compare it to the Slimline Pitts that i so fondly remember. The MTW-75 canister is a high volume muffler so it should be fairly quiet without robbing any power from the engine. I'll report RPM numbers after I get a few tanks through the newly rebuilt DA-50R.