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!


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).


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.


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.


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.


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.


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.


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).


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.


Now I just need the weather to cooperate!

Crashed My Freewing Rebel Today :(

Well after a very successful maiden last week, I had a very unsuccessful third flight today. After about 2 minutes in the air this morning, the EDF quit in flight and I ended up “lawn-darting” her in.


The battery had plenty of charge left so it wasn’t a brown out due to a low battery. I could still move the control surfaces, so I know it wasn’t due to loss of radio signal. I assumed either the motor fried or something went wrong with the ESC.

After getting her home and doing a bit of disassembly, I discovered that the motor to ESC wires had come loose!!! How does this happen in flight? They must have been loose from the factory.

Unfortunately, the connection is hidden when the fan unit is installed and I never thought to remove the fan to check the connections. After-all, I never had anything go wrong on bench tests before her first flight. It just never occurred to me to even think about checking the ESC connections.

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Well lesson learned! From now on, I will be double-checking all connections and mechanical joints on any ARF I happen to buy.

To make matters worse, I had a new 4S 3000 mAh pack (only used once before) in the plane that got a bit crunched too. The pack is deformed and feels a bit squishy (not like its puffed), so I think I am going to trash the pack. It’s not worth the $37 to risk fire with a physically damaged pack.


I sent pictures and a description of what happened to Motion RC (where I bought the plane). Maybe they will take pity on me and help me out here. If not, I can pick up a new fuselage for $50 and get her back in the air without too much trouble.

Maidened My Freewing Rebel EDF Today

My wife bought me the Freewing Rebel EDF for Christmas this past year. I have been slowly building up the courage to get her into the air and finally took the plunge today. I had two great flights despite all my nerves and shaking hands – thank god for expo!


She’s definitely faster than anything else I’ve flown, but really stable and well behaved. Take-offs were uneventful, except she feels a bit sluggish until it picks up speed, and needs a bit more take-off roll than any of my prop planes. In the air, she was very predictable and responsive on low rates. I didn’t do anything fancy, but never felt like I was out of control, and at full throttle, she was tearing up the sky! With half flaps, landings are a breeze, really no harder than my old T-28. I did not try full flaps. Flight times are a bit short, I am getting about 3-1/2 to 4 minutes with a 3000 mAh 4S battery, with ending capacity at about 20%.

This was my first Freewing plane, and overall, I am very impressed with the quality. I did end up fussing with the elevator a bit. The stock setup had two pushrods, one for each elevator side inserted into a single hole in the servo arm. While I am sure that this would work fine, I was having a hard time getting both sides of the elevator to travel identically and could only het about 10mm total travel (vs the 16mm recommended).

To address this, I made up a new custom pushrod set by silver soldering two wires together and replacing the clevis links with Du-BRO micro links . I also slightly trimmed the foam ahead of the servo to provide clearance for the pushrods. Most of the control surfaces on this plane use low friction nylon hinges, but the elevator is a standard foam hinge, and felt a bit stiff. So, for peace of mind, I replaced the stock servo with Hitec metal gear servo. Finally, I used a slightly longer servo arm to get a bit more travel. All together, these small changes got the elevator travel up to the full 16mm, aligned, and moving smoothly.


The battery compartment is a very tight fit. The receiver and wires fit, just barely, behind the battery cavity. I needed to trim a small amount of foam from the front in order to fit the pack without mashing the battery wires.

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With the 3000 mAh battery, the plane needed about 1-1/2 oz of weight in the nose to balance. Before gluing on the nose cone, I cut a small hole in the nose, then mixed some lead shot into a bit of 30 minute epoxy and “pouring” it into the hole.

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The only other fussing required was getting the aileron throws set properly. The right aileron had about 3-4mm more travel than the left. Since there are no empty spots on the 6 channel receiver, there is no choice but to join the servos on a “Y” connector. There is no way to trim one servo separately from the other. I’m not sure if the problem is with the servo, or (more likely) with the position of the control horns relative to the hinge line, but to fix the issue, I simply moved the right aileron pushrod to the outer hole on the control horn, and left the left in the middle hole. Travel is now aligned to within 1-2mm.

I probably am fussing a bit more than needed, but fussing is what I do!

I also got in a bunch of flights with my trusty ParkZone F4F today. This continues to be my no-fuss, no-muss plane. Like their tagline says “Just Fly”.

On the other end of the spectrum is my E-flite Hurricane. This is my “repair after every flight” plane. I had one fairly good flight with her today, but landed a bit hard and pulled the right landing gear mount out of the foam (again). No damage to the foam and, in truth, this is working the way it is supposed to (easier to glue the mount back into the foam than it is to repair a broken wing!).

Lots of Flying Last Week!

Well I took a couple of days off last week to extend the Fourth of July holiday and I was able to get in several more trips to the field. I did have a few more minor mishaps but also a few successes, so all in all, a great couple of days!

I got my F4F back up in the air after repairing the tail feathers that got damaged when she blew off the bench on the 4th. The first flight was a bit hairy as as it took a LOT of up elevator trim to get her flying right. She was porpoising all over the place while I was trying to get my thumbs in the right place to click the trim. I have not had to click trim settings in flight for a while, so I would pull up elevator, let go to click the trim, but before I could get my thumb there, she was nosing down.

After a few tense minutes, I got her sorted and she was flying great again. After landing, you could see that the left elevator was deformed a bit more than I thought causing the trim problem.

I took her back up again and had a great flight, but on landing, managed to crack the cowl! Fortunately, replacement cowls are still available even though the plane has been discontinued.


Next, I decided to try the Hurricane again. This time, I took off from the paved portion of the runway, and I got her in the air with no incident. Once again, I had a bit of a battle with the trim and again had to dial in a bunch of up elevator! As this was only the second flight for this plane (and I was shaking so bad with the first flight that I never got to trimming!) this was not really surprising (although the amount of trim required did surprise me a bit). I got two conservative flights in with acceptable (if not pretty) landings and called it a day.

I got back out to the field again the next day (without the F4F), but did bring out my FT Viggen. I’m still amazed at how well this cheap Dollar Tree foam board plane flies. While I can keep it under control, it definitely has potential to go beyond my (current) abilities. After the first flight of around 5 min length, the battery (a 4S 3700 mAh) was down to only 14% charge with one cell down to 3.69 volts! Way to low. I reset my flight timer to three and half minutes for future flights.

Finally, I had another mishap with the Hurricane. It started with a fantastic flight. I started really getting comfortable with her and felt like she was dialed in just about right. On landing, I was not too happy with the final approach (I was afraid she was drifting too close to the tall grass off the runway) and when she was just about to touch down, I decided to go around. Well, I was way too late and as soon as I applied power, the left wing tip stalled, dropped and hit the ground. Of course, she ground looped. I thought she was a goner, but the only real permanent damage was another broken prop. Other damage consisted of the right gear strut pulling out of the retract unit, the right simulated exhaust manifold popping off, and some scrapes and dings in the foam. Truth be told, it was cheap learning opportunity,

I hit the LHS on my home from the field and picked up a new cowl for the F4F. They also had a new-old-stock stabilizer assembly for the F4F (no longer available from Horizon), so I grabbed that too (just in case). I also picked up a couple of props for the Hurricane.

Today I got around to getting the Hurricane back together again. The gear strut bolted right back in, and with a few minutes of minor tweaking and adjusting the gear was operating smoothly again. A few drops of hot glue got the exhaust manifold reattached and the new prop bolted right on. She was ready to go again, except …

Earlier (before my last flight), I had noticed the seam on the right rear side of the fuselage seemed to have opened up a little. This was definitely there before my ground loop incident, but was something I had just ignored. I decided to wick in some thin foam-safe CA today while doing my other minor repairs. You can’t really tell from this picture, but I ended up making a bit of mess with CA running everywhere but where I wanted it to go. Oh well, no real harm and no one will ever call this bird a hangar queen!


Multiple Mishaps Today

Spent the morning at the field today. It was a bit crowded, and although the weather started out beautiful, the wind started gusting a bit by mid-day, so I did no get quite as much flying time in as I had hoped. I got in a a few flights with my Park Zone P51 and F4F, but then ended up with a couple of minor mishaps.

First up was a gust of wind that blew my F4F off the bench when my back was turned. It landed up side down and end up putting a small break in the rudder and elevator. Easy to fix, but ended the F4F’s flying for the day.

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Next up was an attempted flight with my e-Flite Hurricane. This would have been my first flight for this plane this season and only my second flight ever for this particular plane. I decided to fly off the grass instead of the paved portion of the runway. I just started my take off roll and was getting up to speed, but I hit a bit of rough patch and the plane took a few strange bounces and end up nosing down and breaking the prop. No other damage, but I did not have a spare with me, so a second plane ended up out of commission.

I thought about putting up my PZ P51 again, but given the wind gusts and the way my luck was running I decided that it would be better off calling it quits for the day. Still better than a day at the office though!

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