TF Cessna 182–Stab Construction Continued

Since I will be using Robart hinge points instead of CA hinges, the next step in the stab construction was to locate and drill the holes for the hinge points in both the stab TE and the elevator LE. I started by marking a centerline down the stab LE and the holes based on the location of balsa blocks installed when assembling the stab.

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Looks good, but there were two problems; 1) I did not notice that the ribs in the elevator are offset from the ribs in the stab, so the center hole ended up right on a rib. 2) I used an older twist drill and despite best efforts, I did end up with a small bit of drill wander and some of the holes were not aligned with the center-line. So, plugged up the holes with some scrap balsa glued in with Titebond, and started again, this time with using a sharp spade-point bit.

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After getting a good set of (near) perfectly aligned holes in the elevator LE, I clamped them LE to the stab and transferred the holes to the stab TE.

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Although holes are lined up perfectly in the TE, when drilling through the balsa blocks, I got a bit of drill wander again (ugh), with on hole exiting above center and another exiting below. It should be good enough though as the LE moves freely when mocked up with the hinges.

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Next up is the cross grain reinforcement between the center ribs, and finally the sheeting.

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After removing the pins, I added an extra fillet of Titebond around all the ribs, the LE, and the TE.

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I will be traveling a bit for work, so it will be a while before I will be able to get to the bottom sheeting. At least it will give the glue plenty of time to dry!

Total build hours to date: 19.5

TF Cessna 182–Construction Begins

After sorting out the problems with my building board, I am ready to begin building! As is typical, construction begins with the tail feathers. The dies must have been new and sharp when this kit was punched out, all the parts have very clean crisp edges with no sign of “crushing”.

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The die cut lines are so crisp, that it is hard to tell the rib bottom from the building tab, so I flipped over each rib and used it to mark out the rib profile on its mate.

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Then I used my angle sander to bevel the edge of each rib to fit tightly against the leading edge.

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The rear trailing edge is made up of three pieces. The instructions call for them to be positioned on the plans for marking, then removed and glued together. I was afraid that it would be too hard to keep the assembly aligned and straight doing that, so I started by gluing the center section of the TE to ribs S3 to establish a horizontal datum.

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Next, I glued the outer sections with Titebond while aligning to the outer ribs and using my laser to ensure all was straight and true before the glue set. I’ll confess that it took me two tries to get it right.

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After that, it was straightforward construction. I did deviate from the plans slightly to add balsa blocks for hinge points.

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Here is the stab ready for sheeting.

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And finally, I have prepared the sheeting using a few drops of my last precious tube of Ambroid.

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Note: I am keeping a log of my build time and will be recoding it with each post.

Total build hours to date: 13.5 (no one ever accused me of being a fast builder)

New Build Project–Top Flite Cessna 182

The building bug bit me again, and I decided to start on a new project. I know that I should finish one project before starting another, but I get bored easy and like to mix things up.

The woodworking phase is my favorite part of building, so I wanted a large(ish) project that involved a lot of wood. After looking at my stockpile of kits, I opted for the Top Flite Cessna 182, which I picked up for a very attractive price several years ago.

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While I will be no-where near Top Gun level, I will try to keep this as close to scale as possible. My plan is to ‘glass and paint this plane (as opposed covering with film). As of right now, I am leaning towards finishing this off in a Civil Air Patrol scheme, similar to the photo below.

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Of course, I will convert it to electric power. Other plans include the installation of the Top Flite interior kit, lights, and replacing the static front strut with the Robart articulated one.

After unpacking the box, I discovered that the front windscreen, although still in its factory wrapping, was damaged. Its a bit hard to see in the photos, but there was a crease on both sides of the windscreen. Perhaps with a bit of coaxing, it could be salvaged, but I didn’t want to start a new project with a major component like this in question.

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These units are out of production, but I placed a “wanted” ad on couple of RC boards and was able to find someone with a “new old stock” canopy set from Top Flite that he was willing to sell. The seller only charged the me original price of the set plus his shipping cost, but that still added up to $53 (which is just bit less than 1/4 of what I paid for the original kit INCLUDING the interior set)!

Next up will be start of construction.

Building Board Blues

I was about to get started on a new building project (more on that later) and pulled out my balsa building board. It’s been a while since I last used it, and much to my dismay, I discovered that it had taken on a bit of warp. The mid section of the board had taken on a crown of about 1/32” – 1/16” relative to the ends.

My first attempt to flatten the board was to clamp and weight it down to my bench. This worked and between the clamps, weights, and few paper shims, I was able to get the board to within about 0.010” of flat. Not pretty, but this could work. Then I discovered that the clamp was blocking my bench drawer from opening … oops!

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I really wanted a more permanent and less awkward solution anyway. After a bit of searching, I found this post on RC Universe. Eureka, I can do that too!

A trip to my local big box store yielded some 1” square aluminum, corner brackets, and assorted screws. A few hours later, I had the the following:

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I am back to being within about 0.010” of flat (measured with a straight edge and feeler gauge). Good enough!

I still want to build a true torsion box table one of these days and have a truly dead flat surface, but this should give me a very flat and stable surface.

On to my next building project!

Finally Maidened My H9 Cub

I finally got around to maidening my H9 Cub this weekend, and am pleased to say it was a complete success!

Given how she fought me every step of the way while building, I was half expecting the maiden to be another exercise in annoying little problems. In fact, it almost did turn out that way. My first take-off attempt found her pulling much harder left on take-off roll due to p-factor than I was prepared for. She got into the tall grass next to the runway and nosed over, fortunately, not going fast enough to do any damage.

The next attempt, I was completely prepared and got in enough right rudder to get her airborne without any mishaps. She still yawed a bit more left on climb-out than I would have liked, but not to the point where it caused any problems.

Before flying, I measured static power at 552 watts with a 13×8 prop, which put her at about 72 watts/lb. This is well within acceptable range for a Cub, but below the target of 100 watts/lb I usually try to aim for. I was a bit concerned that she would be underpowered, but no problems there at all. She climbed out well and I was able to fly her around on about half throttle.

She was very stable in the air, and easily handled the 8+ mph wind gusts we were getting at the field. As expected, she needs a bit of rudder to get a smooth turn (it is a Cub after all). She landed a bit faster than the foamies I am used to flying (even with the throttle cut) but, I was able to get her to settle down on the mains without too much fuss.

I cut the first flight short to see how the battery held up. After about 2-1/2 minutes of flight time, battery capacity was at about 70%, so no problem there either.

The second flight was just as un-eventful. In fact, I thought I was going to have a perfect landing, but she went a little long and rolled out past the end of the paved section of the runway onto the grass, resulting in a nose-over (but that’s nothing new for me!). After about 5 min of flight time, battery capacity was at about 45%.

I did not play with trims any, as she seemed to be flying well without any porpoising or other obvious trim issues. Unless there is something obviously out of whack, I try to get a feel for how a plane handles with a few flights before I fuss too much with trims anyway. I may add in a bit of right thrust to help counteract the p-factor before my next flight though.

All in all, I came away quite happy. Flying the Cub should help me build confidence with larger and heavier planes (and particularly with tail draggers) before flying my kit built planes like my Hog Bipe.

Final Tweaks To H9 Cub ARF

Well I planned to spend an hour or so with the final tweaks to the H9 Cub ARF this weekend, but it turned into quite a bit more work than I thought. I started by checking the balance with my Vanessa balancing rig. If you have never used a Vanessa rig, it is a simple tool for finding the center of gravity for any plane (I’ll post a bit more about my setup and its use in the future).

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I turns out that I needed to shift the battery pack as far forward as possible to get close to balance. This shouldn’t have been a surprise since the motor and ESC combined together are lighter than the glow engine this plane was designed for. The battery more than makes up for this, but in the location I originally placed it, much of that mass was behind the firewall.

No problem, since there is plenty of room in the cowl to slide the pack forward, EXCEPT… I now need to turn the pack around and face the wires towards the back as there is no way to reach the plug inside the cowl. No problem, EXCEPT… the battery wires from the ESC don’t quite reach far enough to connect with the battery. So, now everything has to come apart so that I can add about 1-1/2 inches to the ESC battery wires.

I do realize that is typically never a good idea to lengthen the battery to ESC wires, but 1-1/2 inches should not be much of a problem and the total wire length from ESC solder point to battery connection at the pack is still only about 8-1/2 inches (anything over 12 inches typically requires additional capacitors to be added).

Everything back together and I try the balance again. It is much better, but still about 5/16 behind the ideal location.  Note: The forward mark in the photo below is the ideal location at 3-1/4 inches behind the leading edge. The mark behind it represents where the plumb bob should point to mark that spot (compensating for the fact that it is offset by 1/2 of the dowel thickness that the plumb bob string is hanging from).

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It will take about 5 oz or so of additional weight to get the balance on the money. But since the plane is already coming in overweight by about 11 oz, I think I will call this close enough. Note, I was a bit surprised by how much overweight the plane is until I discovered that the combined weight of the battery, motor, ESC are about 8 oz heavier than a glow engine sized for this plane (although I would have that at least some of that would have been offset by eliminating the fuel tank, the receiver battery, and the throttle servo though).

So, after the better part of a Saturday afternoon (and a bit of Sunday morning), the balance is finally done. Now just a few minutes to set the control throws. The elevator goes quick enough, as does the rudder (although it is not possible to get the full travel called for without hitting the elevator, reconfirming that this older ARF is not at all up to today’s standards).

The ailerons however are another story. The ailerons must be set with a differential throw to prevent severe adverse yaw tendency inherent to both full size as well as model Cubs, with a greater down aileron throw vs up. No problem, I installed the servo arms at an offset angle (as called for in the manual) which will build in the differential. In addition, I am using a 6 channel receiver with a separate channel for each aileron, allowing me to fine tune the travel for each. EXCEPT… at full down aileron throw, the pushrods are binding against the mounting hatch (did I mention that the quality of this ARF).

This turned into another lengthy trial and error project of trimming the aileron hatch, adjusting the initial angle of the servo arms, and adjusting the travel limits separately for up and down motion for each aileron. Nothing extraordinary complicated, but time time consuming. You can see in the photo below the notch that needed to be cut in the hatch to allow full pushrod travel without binding.

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At this point, I am calling it done! I’ll give here a good once over to make sure everything is secure and all fasteners are tightened up before taking here out for a maiden, but I am definitely getting tired of fussing with this ARF (I guess I got what I paid for!).

Hanger 9 80” Cub ARF

Several years back, I picked up and older Hanger 9 80” Cub ARF. It was unassembled, and all the parts were there, but in truth, it could best be called fair condition. The covering was badly wrinkled, the plastic windscreen was a bit dented, and the fiberglass cowl had a crack in the bottom. But the price was right, so I thought I’d give it go.

Compared to newer ARFs, this was quite crude. The control surface needed to be hinged, the wing mounting dowels and bolts needed to be drilled, and all the clear parts cut out, trimmed, and installed. The dummy engine bits were just white vacuum formed plastic and they too needed to be cut, trimmed, glued to the cowl, and painted. Pushrods needed to be assembled from balsa dowels and piano wire, and even the tailwheel wire needed to be bent to shape from straight stock piano wire.

I started picking away at it as a fill in project, and (of course) converted it to electric power, using a Turnigy G46.

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There are some scale details I have yet to add (like non-functional wing struts), but she is finally about ready to fly. Not too much to look at, but I am hoping she will be a good flyer.

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Looking forward to some warmer (and drier) weather to try her out!

Rebel Ready To Fly Again

The guys at Motion RC took care of me after my Rebel crash and provided me with $50 store credit to offset damages, which more than covered the cost of a new fuselage kit.

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Everything else was salvageable, so this was the only replacement part necessary for the plane itself.  For piece of mind, I will scrap the battery back from the crash since it appears a bit damaged. So in the end, my only out-of-pocket cost is under $30. Not bad.

Reassembly was easy. The fuselage kit comes complete with plastic for the nose gear, a new canopy, tail and nose cones, and even servo extension cables pre-installed, so this was mostly a bolt together job. The nose gear strut and the pushrod connecting the nose gear steering servo were both slightly bent, but easy to straighten.

After reconnecting the ESC to the fan, I wrapped the connections tightly with electrical tape. That should keep them together.

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Since I had everything out on the bench, I decided to replace the “T” style battery connecter with an EC3 (I don’t the way the “T” connectors spark when you mate them). The EC3 was tight fit through opening in the fuselage, but with a little coaxing, it squeezed through.

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Of course, this meant I had to pull back the pre-installed servo extensions to make room. I was a little concerned about getting the throttle connector and servo extensions back through this tiny hole, but using a length of nylon pushrod sleeving, it was easy to fish them through.

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Everything else then was just bolted/glued in place. Since there was a small crack in the original canopy, I decided to use the new one provided with the fuselage kit. Like last time, I carved a small bit of foam from the underside of the canopy to allow for battery clearance. The plane rebalanced with about 1.3 oz in the nose (like last time).

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For good measure, I will re-verify all my control throws, but there is no reason to expect anything has changed since the wing and tail were undamaged and no changes were made to the electronics. Here she is ready to re-maiden.

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Now I just need the weather to cooperate!

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