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Old 07-07-2018, 09:52 AM
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Build Log
Midwest's Giant Sweet n Low (or High?)

A friend and fellow club member needed to sell off his stash of RC stuff and this Giant Ugly Stick caught my eye. When I just started getting into the hobby in 1971, I built a Midwest Das Little Stick with a .29 Enya engine and a Heathkit radio I built.

Out of nostalgia, 47 years later, I decided to build another, following the same color scheme, but instead of a small one, I chose to build my first gasser airplane.

Not to complicate things, but for fun, I also decided to make this plane "ambidextrous" or both a Sweet n High as well as a Sweet n Low. I searched websites and couldn't find this type of build so I thought people who enjoy a good sport plane might also enjoy this build.

These are the build problems I anticipated before starting. The last problem #10 was encountered after the build. It's very significant and should be considered while building the front end of the firewall. The firewall should be moved forward; the moment of the balance is heavily based on the chosen engine. All I can say is about 1.6 lbs. was needed to balance the CG. Why? The original designed assumed a Quadra 35 at 4.79 lbs. A DLE 35RA only weighs about 2.5 lbs.

1. Fin Removal / Reversal
2. Rudder Removal / Reversal
3. Tail Wheel Removal
4. Servo Rod Locations in Same Spot for Fin Reversal
5. Landing Gear Reversal
6. Wing Reversal
7. Fuel Tank Plumbing
8. Nose Wheel Removal
9. Wing Servo Protection.
10. CG and Balance (Must be considered first on a new build.)

I'll post what I did and my successes with it to see if others want to do it also. Two planes in one? Why not? I'm sure ther are other ways to engineer it, but here goes. I'll break the build down as I did it and how I did it.

Here are pictures of the Little Stick I took from a digitized 8mm movie and the plans from the kit no longer in production.
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Last edited by szempruw; 07-13-2018 at 05:42 PM. Reason: Added build problems and engine weights
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Old 07-10-2018, 05:29 PM
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Wing Repair

Another friend already had a wing made and gave it to me. It was in a crash but the wing was not too badly torn up. It was a lot faster to tear off the covering and patch it up. It does have a slight dihedral per plans, We save body bag parts for our friends, right?

The center dowel is brand new and made of oak.

Re: Problem #9, I made a little box to cover the servos. I'm not sure yet if I will use it.
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Last edited by szempruw; 07-12-2018 at 02:06 PM.
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Old 07-10-2018, 05:49 PM
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Fin and Stabilizer

I built the fin and stabilizer and chose to use aluminum angle stock to attach and remove the fin. Since these parts are skinned with 3/32" sheeting, I used 3/32" plywood to reinforce them The dimensions are in the pictures.

For Problem #1, Both the bottom of the fin as well as the top and bottom of the stabilizer and rudder are all reinforced.

I've built tail draggers before and they were weak at the bottom where you like to install rudder control linkage. So, I felt it prudent to reinforce the bottom of the rudder with plywood.
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Last edited by szempruw; 07-12-2018 at 02:06 PM. Reason: ID Problems solved
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Old 07-10-2018, 06:22 PM
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Tail Feathers

I didn't take a lot of pictures to show all the steps building the fuselage because it's just a box. But it needed a change here to accommodate the fin installation on the top or the bottom of the fuse. But I'll comment here that if I did this build again, I'd make the nose of the fuse longer. I'll explain why later. It's about CG.

The kit has a trapezoidal plate at the rear. Since I was also going to mount the fin on the bottom, for Problem #1, I needed some meat to attach the aluminum angle stock. This is the side opposite the Stab attachment, the "true" tail dragger build position.

This piece turned into an hour glass shape that would accept both the tail gear assembly and the fin. The S862 Sullivan tail wheel assembly is a nice product and is steerable.

The attachment of the fin would be with 4-40 screws so I used blind nuts. I drilled 6 holes per side into the angle stock first and the used the stock to locate the holes in the plywood for the fin.

I then glued this plate, using the fin as a guide, to the fuselage. When set, I reinforced the inside with 1/4" triangle balsa while I could still get my hands in there, and on the outside.

Re: Problem #3, Lastly, I fitted the tail wheel assembly with blind nuts.
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Last edited by szempruw; 07-12-2018 at 02:05 PM.
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Old 07-12-2018, 02:04 PM
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Stabilizer Attachment

I added 1/4" triangular stock to reinforce the stabilizer attachment. I temporarily mounted the fin to the stabilizer. I then used the assembly, shimmed as needed and clamped to make sure the fin mounted on the fuselage's centerline. I sanded then epoxied this surface perpendicular to the table.
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Old 07-12-2018, 02:31 PM
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Rudder Linkage and Attachment

Problem #4: Once I sheeted the rudder, I started to look at the rudder hinge locations and the control linkage. At this point I believed I needed the same control horn on both sides of the rudder and if located properly, I could use the same servo. I thought Push / Pull might work, but I might get better control adjustment with horns. Between the two Dubro packages #866 and #913, I scavenged parts to make a symmetrical horn arrangement. I had to get a longer 4-40 Allen screw from the hardware store. I picked the fin attachment spot and reinforced it with 3/32" plywood.

Problem #2: It was at this time that I realized that the Rudder could be permanently affixed to the fin using Dubro hinges with one caveat, the bottom hinge. When I trial fitted the fin/rudder assembly as a Trike and/or a tail dragger, the bottom hinge location just didn't match up right. The barrel of the hinge would not fit in both configurations. The best solution was to epoxy one side of the hinge into the fuselage and then bolt the fin side onto the rudder using 2-56 screws and Nylock nuts. The result was two hinge halves one for Trike and one for Tail dragger configuration.
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Old 07-12-2018, 03:05 PM
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Nosewheel / Landing Gear

Re: Problem #8, I searched the web for an "industrial size" Nosewheel. The spring type was instinctively not an option. With some good advice, Derrell Tenny at Sierra Retracts recommended a nosewheel originally designed for a Cessna 172 scale plane. He was thoughtful and we discussed prop clearance and mounting issues I wouldn't have normally considered. To me, this robust 1/2" shock absorbing steerable nose gear was the perfect solution for about $95.00. (cost at this time)

My initial plan was to mount the nose gear inside the firewall as the pictures show. When Problem #10 came up, I switched to mounting it on the outside as will be seen and discussed later. I used T-nuts in the firewall and the wheel can be easily removed.

Re: Problem #5: I checked other Ugly Stick drawings and researched the optimal rake and location of the wheels for a tricycle landing gear plane. I determined that a 1/4" plywood plate should be located 14 1/2" from the plan's firewall. The gear plate was reinforced with 1/2" balsa triangle stock. The gear was centered and the bolt pattern made identical for both configurations. I drilled for 10/32" mounting screws into the gear used it as a template

The plans call out 3/16" balsa sheeting aft, and I changed to 1/4" sheeting to blend into the plywood.

I chose to make a fuel tank hatch on top as a tail dragger.
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Last edited by szempruw; 07-12-2018 at 04:12 PM.
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Old 07-12-2018, 03:11 PM
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Tail Dragger or Trike?

These pics are showing the status of the two configurations. The visitor was not welcomed. We were cat sitting that weekend and yes, they are curious!

Since I already had mounting holes in the wing, I aligned the wing measuring the tips to the stabilizer and drilled through. On a new build, make sure the angle of the drill is considered for both configurations. I had to open the holes in the wing just a tad to account for this, i.e. give it a little slop to cover attachment in both directions because of the dihedral. The point is just check both ways before drilling through the fuse's maple blocks.

Re: Problem #6: With the use of RTV in the wing saddle, and the use of 1/4" fender washers, the wing reversal problem was found to be minimal. As a Trike, the servos are exposed and as a Tail Dragger they are hidden. If I were to build the wing, I'd put the servo's inside the wing under hatches for cosmetic reasons.
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Last edited by szempruw; 07-12-2018 at 04:09 PM. Reason: Wing Mounting
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Old 07-12-2018, 03:41 PM
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Fuel Tank Location and Plumbing

Since this is my first gasser, I rationalized a 12 oz fuel tank for a 10-12 minute flight. This is your choice. I'll address flying last, but in retrospect, a slightly bigger tank would have been better. it really all depends on how you fly and how you finish this compartment. Moving the nose gear outside gave me more room.

However, the key issue here for Problem #7 is plumbing and venting. I found this fuel fitting at B&B Specialties and bought two. You want the tank vented at the top. But since the configuration changes top to bottom, I needed a fitting that would either be shut off (plugged) or open. Maybe there are other fittings out there somewhere.

I biased the fitting location towards the top or bottom. The top fitting would become the vent by just removing the cap. For both fittings, I ensured that the tubing inside the hatch was looped.

BTW, I had some carbon sheeting left over and I reinforced the firewall.
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Old 07-12-2018, 03:57 PM
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Ignition Cut Off / Battery

As can be seen from the pictures, I started covering the fuse with red Monokote. I made a removable floor to house and separate the ignition module and battery from the tank. I wanted to try and use the ElectroDynamic's Opti-Kill electronics as the radio operated kill feature.

I also wanted to try an RPM meter. My choice for ignition and flying batteries are 2-cell LIFE. ElectroDynamic has a nice switch that allows you to make a charging wire and not have to remove the batteries from the plane. I WOULDN'T DO THIS with Lipo's due to fire risks. All my planes have LiFE Rx batteries.

With nose wheel steering linkage and all, this area started to get a little crowded, but was still manageable.
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Old 07-12-2018, 04:01 PM
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Engine Mounting

The following pictures show the DLE 35RA engine mounted using the original standoffs.

Due to Problem #10 , this mounting latently changed radically.
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Old 07-12-2018, 05:00 PM
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Oh No! Problem #10

Re: Problem #10, Once I weighed the plane checking the CG, I could see that I was way off. The CG was 61 mm Tail Heavy and about 1500 grams were needed.
I used an Excel spreadsheet template I found in the forums to plug in the scale's weight readings in grams. It gave me the total weight, distance from ideal CG, and weight needed.

Why so tail heavy?? After researching this, I realized that the original design was for an old Quadra 35 at 4.79 lbs. I'm using a modern DLE35RA at 2.55 lbs. Almost 1/2 the weight and twice the horsepower!

I started a number of changes in succession and then re-weighed the plane.

1. I moved the servos, which I fortunately built on a tray, forward as much as I could.

2. I ditched the original standoffs and went to Grainger and bought 3.5" hexagonal standoffs. 3 inches wasn't enough. That was about 300 grams each. It also kicked the engine foreward changing the moment.

3. I changed to smaller and lighter landing gear wheels. And the largest nosewheel I could fit.

4. I removed 2 screws from the fin on each side thinking I might have put too many in the first place.

5. I ended up adding lead sticks to the firewall

I used two on-line programs to verify the CG location. One said I was 9 mm tail heavy, the other 3 mm nose heavy. In reality, I am about 1/4" behind the recommended plan's CG.

With the discreet changes I made, I ended up adding 1.6 lbs. getting the CG close enough to attempt a flight.
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Last edited by szempruw; 02-02-2021 at 10:59 AM.
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Old 07-12-2018, 05:27 PM
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Trike Flying

Here are pictures of the Trike configuration. The maiden voyage was July 3rd, 2018. Like I said, this is my first gasser and a fellow club member and I used a buddy box together.

At first, the engine needed a little tuning. I had about an hour of bench running time to break it in.

After he trimmed it out a little, I got to fly it. On all accounts it flew well. The DLE 35 RA was more than enough power. I kept the flight timer to 10 minutes. I'll probably change to 11 minutes. Perhaps a slightly bigger tank would add some cushion. I was nine cranks from being empty on the last flight. The engine is breaking in nicely and is starting more easily. I've got three flights on it by now. One thing I can see is that it takes more field to take off and land than my nitro or electric planes.

The CG location seems just fine. It settles in for a landing with a nice slow nose slightly down approach.

Next time I'll be eager to try out my Taranis S8R receiver and the auto-leveling functionality.

So far, I'm enjoying this plane and the Trike configuration. When I feel like switching to the Tail Dragger configuration, I'll make one more post to round out this build story.
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Last edited by szempruw; 07-12-2018 at 05:31 PM. Reason: Typos
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Old 08-04-2018, 01:35 PM
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Hello zempruw
I am interested in hearing how the S8R works for you regarding auto level functionality on a gasser. If you have any issues regarding the S8R, you may want to consider the Hobby Eagle A3S3. Good Luck.
Randy
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Old 08-26-2018, 08:58 AM
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S8r and Gas Engine

Quote:
Originally Posted by rkorenek View Post
Hello zempruw
I am interested in hearing how the S8R works for you regarding auto level functionality on a gasser. If you have any issues regarding the S8R, you may want to consider the Hobby Eagle A3S3. Good Luck.
Randy
Well Randy, funny you asked. I had 3 good first flights without turning on the auto-leveling feature. On the 4th, using the 3-position switch for channel 10, it was turned on. The plane changed attitude just a bit, and I chalked that up to receiver installation. Aerodynamic stability might not be the same as the physical installation. That is why the pc software allows for a few degrees of attitude adjustment to compensate. Making a mental note for adjustment, I kept it flying. Fortunately, a experienced gasser pilot and friend was flying it. All of a sudden, in normal mode, the rudder locked hard left. We didn't know it was the rudder till it was landed. The lock was intermittent. My friend's skill and some altitude kept it from crashing. On the ground while taxiing back, we saw the rudder lock over for a few seconds. Honestly, this really spooked me. I rechecked all the setup functions using the latest version upgrade and thoroughly bench tested. I left the gain setting at the default values and performed the Self Check. All is ready for another flight, but I decided to switch the Rx to a standard Rx, a spare V8R-II I had.

I've searched and read about possible ignition interference as a cause, but right now, I'm not sure I know how to diagnose the problem. Perhaps taxi around to make sure vibration is not the problem. I had the Rx installed on two plywood plates, both are on grommets to try and isolate vibration. I also thought this would allow for minor attitude adjustments like a four post table.

The plane flies well. I'll look at your suggestion for alternative auto-leveling gear. Vibration? Interference? software bug? I just don't know right now.
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