Downsizing and Building Wings - DeBolt Soarer

    Have you ever found a model plane design that you like, with a plan, but the thing is just too big? Maybe you thought about downsizing the plans?
    I used to do it back before we had AI and all the technology that goes with it, and frankly, I just eyeballed everything in those days.
    But I got to wondering how AI tools might help with this. My interests are in small field, built-up models in the 50” span range, especially gliders and e-flite. So I figured, “Hey, why not try it and see if AI Google can help?”
     And since this hobby has been around a long time and this is not rocket science – although, to be honest, it is close - there is a lot of already tested and verified info about doing this. This means AI has a lot of source data to pull from, without too much worry over error. ....so let us see how it did.

    What I specifically asked AI Google about was the practical limits for downsizing RC model aircraft plans.
>>> Google AI: “It can be readily done, but it isnt a simple reduction. The limits fall into two main categories...”

- Aeronautical Physics (specifically the Reynolds Number)
- Structural mechanics

Your ability to scale the lines on a sheet of paper are not what matters here. While you can technically print a giant-scale plan at 10% of its original size, the physical air molecules that the aircraft will fly through do not scale down with the airplane. Air behaves much more like "thick syrup" to a tiny wing than it does to a large one.
The practical limit, it seems, sits at a wingspan of around 13 to 15 inches (approximately 33 to 38 cm) for a standard balsa plan conversion. Going smaller requires moving away from traditional scaling into highly specialized micro-engineering.
With that said, here are the critical engineering thresholds that dictate your scaling limits:

1. The Aerodynamic Limit (The Reynolds Number Wall)
As an airfoil shrinks, it becomes vastly less efficient. The Reynolds Number (Re) measures how air flows over a surface.
* The Breakpoint
Once a wing chord (the width from the front of the wing to the back) drops below 2.5 to 3 inches, the air molecules fail to smoothly follow the upper curve of the wing.
The Result - The wing suffers from constant flow separation, causing an abrupt drop in lift and a massive spike in drag. If you shrink a plan too much, an airfoil that flew beautifully at a 60-inch wingspan will suddenly act like a flat piece of plywood, stalling easily and requiring excessive speeds just to stay airborne.

2. The Weight-to-Volume Dilemma (Cubic Wing Loading)
When you scale down a plan by half, the wing area drops by a factor of 4 (0.5 × 0.5). However, the internal volume of the fuselage and the structural mass do not drop linearly. The comes the The Structural Strength Limitation, where a piece of 1/16-inch balsa wood cannot easily be scaled down to 1/64-inch wood – while expecting that it retainins the strength to hold an RC motor, battery, and servos.
The Result - Downsized planes usually end up dangerously overweight relative to their tiny wings. If your scaled-down build exceeds a Wing Cubic Loading (WCL) of 7 or 8 for a micro model, it will fly like a brick, requiring blistering landing speeds that will easily damage the model.

3. The Hardware Threshold
To downsize below a 15-inch wingspan, you can no longer use standard independent servos, receivers, and speed controllers. You hit a practical barrier where you must switch to:
* All-in-One (AIO) Brick Boards: Integrated receiver/ESC/linear servo units (like those found in Horizon Hobby UMX planes).
* 1S Lipos and Coreless Motors: Traditional brushless motors and 2S/3S batteries quickly become too heavy.

Rules of Thumb for Downsizing Plans
With all that said, let's talk about practical applications. If you want to downsize a plan and still have an enjoyable, stable flyer, use these adjustment guidelines:

* Modify the Airfoil: If you downsize a plan to a micro scale (sub-20-inch wingspan), flatten the bottom of the airfoil. True under-cambered or thick symmetrical airfoils perform terribly at ultra-low Reynolds numbers.
A flat-bottom or thin, slightly curved plate profile generates much more predictable lift at tiny scales.
* Increase the Chord Width: If you scale a plane down by 50%, for example, consider cheating slightly by scaling the wing chord down only 40%. Making the wing slightly wider front-to-back keeps your Reynolds number higher and drops your wing loading.
* Increase Dihedral: Tiny planes are easily knocked around by the slightest outdoor breeze. Increase the wing dihedral (the V-shaped upward angle of the wings) by 1 to 2 degrees beyond what the original plan states to give the model better self-righting stability 2 degrees beyond what the original plan states to give the model better self-righting stability.

Real World Values
AI Google then asked me to provide some specific data, to attempt a calculation for target wing loading so it flies smoothly, and to provide a practical experience. Thats pretty cool, right?!
It directly asked for the following:

1. Original wingspan of the plan to be reduced
2. How small are you hoping to take it?
3. Specific type of plane (e.g., a slow park flyer, a sleek fighter, or a glider), I can help you calculate the target wing loading so it flies smoothly.
My response: 78 inches down to about 50, glider for small fields
Google AI Respone: “Downsizing a 78-inch plan down to 50 inches puts you in an absolute sweet spot for R/C modeling!...”

You are scaling down by 36%, or roughly to 64% of the original size. Unlike micro-modeling, a 50-inch wingspan is large enough that you completely avoid the nasty aerodynamic penalties of low Reynolds numbers. Air will still flow smoothly over the wings, and you can use highly reliable, standard-sized electronic components.
However, you cannot just print the plan smaller and build it blindly. Because you are reducing the overall wing area by nearly 40%, you must adjust the internal structure to prevent the plane from becoming an overweight brick.
Here are the precise structural and mechanical conversions you need to make to successfully downsize from 78" to 50":

1. Wood Thickness Conversions
If you use the original wood sizes specified on a 78-inch plan, your 50-inch model will be vastly over-built, quite heavy, and the balance will be off. Instead, use this conversion guide to re-size your materials:

O - riginal 78" Plan Spec
N- ew 50" Build Size
U- sage Area

O - 1/4" balsa / ply
N - 3/16" balsa / ply
U - main fuselage formers, firewall (ply)

O- 3/16" balsa
N- 1/8" balsa
U - fuselage sides, heavy structural bracing

O- 1/8" balsa
N- 3/32" balsa
U- wing ribs, fuselage sheeting, tail surfaces

O- 3/32" or 1/16" balsa
N- 1/16" or 1/32" balsa
U- trailing edge sheeting, cap strips

O -1/4" x 1/4" balsa sticks
N- 3/16" x 3/16" or 1/8" x 1/4"
U- wing spars, longerons

• Hardware Tip: If the original plan calls for heavy 1/4-inch steel wire for the landing gear, drop it down to 1/8-inch or 5/32-inch music wire to save substantial weight in the nose.

2. The Weight Target (The Golden Rule)
Volume drops much faster than surface area. A 78-inch plane can more easily handle a heavy build, but a 50-inch plane cannot.
* Target Weight: Your finished 50-inch model should ideally weigh between 2.5 to 4.5 lbs (1.1 to 2.0 kg) ready-to-fly, depending on the type of plane.
* Where to cheat: Leave out unnecessary scale details, drop down to lighter hardware, and consider using a modern lightweight film (like standard Oracover/UltraCote or a light film) instead of heavy fabric and paint finishes.

3. Powertrain & Electronics Strategy
A 78-inch plane usually requires large, heavy 6S LiPo setups or gas engines (20cc–30cc). For your 50-inch version, you step down into standard, more affordable equipment:
* Servos: Toss out standard 45-gram servos. Insteasm source high-quality 12-gram to 17-gram mini/micro servos (such as the Hitec HS-85MG or similar digital metal-gear servos). They offer more than enough torque for a 50-inch plane at a fraction of the weight.
* Electrics
- Motor: Source a 35mm or 42mm outrunner brushless motor (often designated as a "Power 25" or "Power 32" equivalent, around 800–1000 KV)
- Battery: Run a simple 3S or 4S LiPo battery (2200mAh to 3300mAh)
- ESC: 50A to 60A

3 Steps to Prepare the Printed Plan
When you take the digital file to a print shop (or scale it across tiled pages at home), print it at 64.1%.
Once printed, do this before cutting wood:

1. Re-draw the Spar Slots: The scaled-down wing ribs will now have odd, non-standard spar slot sizes (e.g., a 1/4" slot becomes 0.16").
Use a ruler and a pencil to re-draw the spar slots on the plan to match standard wood sizes you can actually buy, like 3/16" or 1/8".
2. Check the Firewall: Measure the mounting footprint of your chosen electric motor or smaller glow engine. Ensure the scaled-down firewall still has enough surface area to mount the engine box or X-mount.
3. Keep the Control Surface Throws: Do not scale down the physical movement (throws) of your ailerons, elevator, and rudder by 64%.
Smaller planes need relatively larger control deflections to feel responsive, so keep the original throw measurements (in inches/degrees) if possible, using dual rates to tune it down later.

Specific Example
>>> Google AI next got down to the nitty gritty and asked:
“Do you have a specific airplane plan in mind. With the model name or design type (e.g., a Piper Cub, a WW1 biplane, or a sleek pattern ship), I can give you the target wing loading and tell you exactly where you can cut weight without sacrificing structural integrity.”
My Response: Hal Debolt glider design, called, "Soarer..."

Google AI response: “The 1982 Hal DeBolt "Soarer" (originally published in RCModeler as Plan 857) is an excellent choice for a 64% downsize project...”
Since it was designed as a gentle 2-channel sport glider, the 78-inch wing is incredibly forgiving.
Downsizing DeBolts 'Soarer' to a 50-inch "Mini-Soarer" turns a lazy, thermal cruiser into an exceptionally nimble, highly transportable park glider or light-wind slope soarer.
Because Hal DeBolt designed his vintage models with sturdy, traditional balsa-and-spruce construction, shrinking it requires specific tactical shifts to protect its gliding performance.

1. The Wing Area & Load Scaling (The Math)
* Original 78" Soarer: Had a massive, high-aspect-ratio thermal wing.
New 50" Soarer: You are reducing the wing area significantly. To keep the original "floating" flight characteristics, your target flying weight for the 50-inch version should be no more than 16 to 22 ounces (450 to 620 grams). If it builds heavier than 25 oz, it will lose its slow thermal-catching abilities and will instead require a brisk breeze on a slope or a fast motor run to stay up.

2. Structural Adjustments for the DeBolt Airfoil
DeBolt designs are notorious for using thick trailing edges and heavy spruce spars. To save weight on the 50" version:
* The Spars: Replace any heavy spruce or hardwood main spars specified on the plan with 1/8" x 1/4" hard balsa or a lightweight 3mm carbon fiber tube/strip. Carbon fiber will give you the same legendary strength as DeBolt's original spruce but at a fraction of the weight.
* The Ribs: The original ribs were likely 3/32" or 1/8" balsa. Cut the new 50" ribs out of 1/16" light or medium balsa.
* Trailing Edge: Rather than scaling down a thick, heavy triangular trailing edge stock, use a flat 1/16" balsa sheet strip for the bottom trailing edge and cap it to keep the tail feathers feather-light.

3. Launch & Power Modifications
Gliders change the most when downsized because launching methods must change. You have three great options for the 50-inch Soarer:
* The "Electric Nose Soarer" Conversion (Highly Recommended):
Slice the nose off the fuselage and mount a small 2205 or 2206 brushless drone motor (around 1400–2000 KV) spinning a small 6-inch or 7-inch folding propeller. Paired with a tiny 3S 850mAh LiPo battery, this will give you a self-launching park flyer that doesn't need a high-start towline.
* Mini High-Start: To go this route, you will have to incorporate a tow hook below the fuselage when you construct the model.
Then, to use it as a pure TLG glider, you CANNOT use the standard, heavy, high-start tube of the original 78-inch glider. That set up will “disassemble” your model within seconds, tearing the wing of 50-inch model right off the fuselage.
Instead you will have to switch to a lighter weight, "Up-Start," or mini high-start. This consists of about 25 feet of 1/8" surgical tubing and 100 feet of light, 20-30 lb. nylon monofilament fishing line.
* Slope Soaring: Leave the nose clean, eliminate the tow-hook, and just launch the glider off a small hilltop or coastal ridge on light-wind days.
This may not be for you, however, since you must have this kind of site at your disposal. So it is not really well suited for inland, “flat-landers.”

4. Choosing the Covering
Since this is a lightweight glider conversion, extra weight behind the wing destroys the planes aerodynamics. In other words, a too-heavy tail requires a lot of dead lead in the nose to balance the Center of Gravity (CG).
* Do not use heavy polyester films (like standard UltraCote or MonoKote). Instead, cover the wing and tail sections using an ultra-lightweight film like Solarfilm SoLite, AeroPOLY, or the classic Polyspan/LiteSpan method we discussed earlier to give it that authentic vintage transparent glow without adding structural weight.

NOTE: After some technical difficulties, I had to restart the Google AI tutorial – and a new set of guidelines came into play. They are similar but also add new wrinkles....

>>> Google AI: Are you planning to build this Mini-Soarer as a pure glider to tow up/slope soar, or are you thinking about modifying the nose to put a small electric motor and folding prop on it?
My response: Lets do it all – make it an e-flite glider with option combo HLG-TLG options.

AI Response: “Alrighty then - converting the downsized 50" Hal DeBolt Soarer into a 3-in-1 versatile aircraft — Electric Launch, Hand Launch (Javelin style), and Mini-Bungee Launch — is a brilliant project....”
Because you want it to excel across three different styles, the layout of the fuselage nose and the structural integrity of the wing joints are critical.
───
⚡ 1. The Electric Power Package – “The Go Stuff”
For a glider of this size, you want a power system that provides a swift, steep climb to altitude, then folds away completely flat to minimize drag when you cut the throttle to hunt for thermals.
* Motor: 2205 or 2206 Brushless Outrunner (1400KV to 1800KV).
This size is commonly used for 5-inch mini-drones. It weighs only about 25–30 grams but produces massive thrust on a small footprint.
* Propeller:6x4 or 7x4 Folding Propeller with an appropriate aluminum spinner hub matching your motor shaft (typically 3mm or 5mm).
Note: Ensure your ESC has the "Brake" function turned ON so the airstream folds the prop blades flat against the fuselage when the motor stops.
* ESC: 20A to 30A Electronic Speed Controller with a built-in BEC to power your servos.
* Battery: 3S (11.1V) 450mAh to 850mAh LiPo (30C+ rating).
Keeping the battery small prevents the glider from getting heavy while still providing 3 to 4 long climbs to soaring altitude per charge.
───
2. Dual-Purpose Nose & Structural Layout
To accommodate the electric motor while maintaining the structural durability needed for hand launches and bungee high-starts, lay out your internal gear sequentially, thus:
[Folding Prop] -> [Firewall / Motor] -> [Battery] -> [ESC] -> [Servos] -> [Receiver]

* The Firewall: Cut a new circular or square firewall out of 1/8” Aircraft Plywood. Mount the motor to it using small machine screws and blue thread-locker. Glue this firewall into the nose these moments:
- A slight hint of down-thrust (1 to 2 degrees)
- A slight right-thrust (1 degree) to counter motor torque during steep climbs.
* Battery and ESC Placement: Place the battery right behind the motor. Because you are adding motor weight to the nose, you will need to push the battery back toward the wing's leading edge to balance the Center of Gravity (CG).
* Servos: Mount two 9-gram micro servos (like the TowerPro SG90 or Emax ES08MA II) down in the fuselage cabin underneath the center of the wing, using pushrods to control the rudder and elevator.
───
3. Modifications for Bungee & Hand Launching
Now, lets discuss bungee launching and hand launching. These two methods are different than the motor-powered option, because they subject the airframe to localized structural forces that pure electric planes never encounter. Therefore, you must modify the plan to withstand these loads:

* The Tow-Hook Placement: For a mini-bungee launch, install a small metal L-hook or threaded screw-eye on the bottom of the fuselage. Place the hook exactly 15 degrees forward of the wing’s Center of Gravity (CG).
If you place it too far forward, the plane won't climb; if it is too far back, the plane will violently pitch up and snap-stall on launch.
* Tow-Hook Reinforcement: Do not just screw the hook into balsa.
Glue a 1/4" thick piece of hardwood or aircraft plywood scrap inside the fuselage floor, and anchor the tow-hook firmly into that block using epoxy.
* Wing Joint Reinforcement: A bungee launch exerts intense bending forces on the wing center-section. When gluing the two wing halves together at the center dihedral angle, wrap the center joint with a 1-inch wide strip of lightweight fiberglass cloth or nylon tape saturated in thin epoxy or thick CA glue. This ensures the wings won't fold under a heavy bungee pull.
* The Hand-Launch Grip: Since you also want to retain the option to be hand-launch (javelin style), sans bungee or motor, sheet the bottom of the fuselage directly under the wing with 1/16" plywood or hard balsa. This gives your fingers a solid, crush-proof area to grip and throw the model firmly.
───
4. Designing the Mini-Bungee (High-Start)
As previously mentioned, a standard, heavy, club-level high-start will destroy a 50" balsa glider. You need to construct a custom, lightweight "up-start" kit:
* The Elastic: Obtain 15 to 20 feet of 1/8” (outer diameter) latex surgical tubing or lightweight exercise bands.
* The Line: Attach 60 to 80 feet of 20lb to 30lb monofilament fishing line or braided nylon kite string to the tubing.
* The Ring and Flag: Tie a small metal key ring to the end of the line (to slip into your tow-hook), and tie a 2" x 6" piece of bright orange ribbon just behind the ring. The ribbon acts as a small parachute/drag flag that pulls the line off your tow-hook automatically once the glider surpasses the peak of the bungee launch.

MORE CONSTRUCTION NOTES
* Removable wing. There are options for the wing attachement:

- Permanent attachment
- Removable wing

Permanently attached wings are quick to get into action and they are less susceptible to changes in trim. But they are ridiculously awkward and prone to damage during transport. They also prevent access to the electronincs inside, and they can break of during rough landings. Maybe if you lived on our own flying field and had a big garage/barn where planes could be stored, permanent attachment might be worth considering. But all things considered, it is almost never done that way.
Most people have to transport their planes to the flying fields in cars, and nearly everyone makes the wing removable – and its definitely the right choice. It makes transporting a 50-inch glider incredibly easy. Besides, it also protects the airframe by allowing the wing to "pop off" rather than break off during a rough landing. It also gives you wide-open access to the fuselage interior to swap out your launch batteries, make adjustments, etc.
For a vintage DeBolt design downsized to 50 inches, you have two excellent choices for securing the wing: Classic Rubber Bands or a Modern Bolt-Down System.

Option 1: Classic Rubber Bands (Best for Hand/Bungee Launch)
Hal DeBolt’s original designs almost exclusively used rubber bands stretched across the top of the wing to hold it on. For a multi-launch combo glider, this remains the most practical method because it offers built-in "crash survival."
If you catch a wingtip in the grass during a hand launch or bungee landing, the rubber bands stretch and release the energy instead of ripping the fuselage apart.
It looks sonething like this when viewed from above:

=======[ Fwd. Dowel ]=== WING ===[ Aft Dowel ]=======

Hardwood dowels perpendicular through fuselage, fore and aft of the wing.

* How to Build It
Drill approx. 5/32” holes through the fuselage sides just below the wing saddle line— each one one about 1/2" ahead of the wing's leading and trailing edge. Push 1/8” - 3/16” hardwood dowels or bamboo skewers through, allowing them to extend about 1/4”-3/8” out past the fuselage sides on each side. Epoxy them securely. Chopsticks could work well for this, and are a good reason to grab some Chinese take-out!
* Reinforcing the Wing
The tightly stretched rubber bands will crush soft balsa. To reinforce the wing hold down, glue thin strips of 1/32” plywood or hard 1/16" balsa scrap over the top center section of the wing where the rubber bands cross over the leading and trailing edges. Some thin PVC or other plastic might also work, so don't be afraid to think outside the box.
* The Battery Access
Now, by electing to use a rubber-banded wing, the wing itself becomes your fuselage access hatch! Simply pop the rubber bands off, lift the wing, and you have total access to the battery tray and electronics underneath.
───
⚡ Option 2: Nylon Bolt-Down (Best for Clean Aerodynamics)
If you are all about aesthetics, you want the cleanest possible lines for efficient thermal soaring without even the minimal drag of external rubber bands. In that case, a single- or dual-bolt system is finctional and elegant.
Viewed from above, it looks something like this...

[Wing Leading Edge Tongue] ---> [ Slot in Fuselage Former ]
===== WING =====
[Wing Trailing Edge ] ---------> [ Nylon Bolt into Plywood Blind Nut ]

* The Front Anchor (Tongue & Slot):
During construction, epoxy a small 1/8” plywood tongue protruding forward from the wing’s leading edge, center. This tongue slides neatly into a tightly-fitted matching horizontal slot cut into the fuselage bulkhead/former just ahead of the wing saddle.
* The Rear Anchor (Bolt)
To secure the wing, you will add a nylon bolt and blind nut at the wings' after center section
Glue a 1/4” thick aircraft plywood block inside the fuselage directly under the trailing edge location. Drill and tap it to match the bolt (usually 1/4-20), then reinforce the threads with several coats of CA glue allowed to sink in to the wood.
Alternatively, press a matching metal blind T-nut into the underside of the block. Cut away a small patch of the covering in the wing trailing, right where the bolt will pas through. Then epoxy a matching plywood reinforcement plate to the wing trailing edge, so the eopxy will bond to the wood. Then drill a hole through the plate, and use a nylon plastic chassis bolt to screw the wing down.
Tip: Always use nylon bolts, never steel! The nylon bolt is designed to shear off cleanly in a crash, acting as a structural fuse to save the wing and fuselage.
* The Battery Access Hatch
Because removing a bolted wing at the field between flights is tedious, you must cut a dedicated forward battery hatch into the fuselage nose. Cut a neat opening on the top deck of the nose between the firewall and the wing leading edge. Add a simple magnet catch or a spring-loaded latch to secure the hatch cover. For this reason, the small penalty in drag when using wing hold-down rubber bands is easily offset by ease of use.

Structuring the Internal Trays (Regardless of Wing Style)
Because you are cramming an electric powertrain, servos, and a tow-hook block into a 50" fuselage, you will want to construct a floating component tray
1. The Lower Deck (The Anchor)
The very bottom floor of the fuselage under the wing saddle should hold your heavy, epoxied tow-hook block. Keep this clear of electronics so the bungee line ring doesn't accidentally snag anything internal if the hook breaks.
2. The Middle Deck (The Component Slider): Glue two thin balsa rails along the inside fuselage walls just above the tow-hook block.
Slide a 1/16” plywood “tray” onto these rails, so that it fits snugly between the fuselage sides.
To this tray, mount your rudder and elevator servos at, or just behind, the center of balance, with the receiver Velcro'd behind them. The RX'r is the lightest weight component in the system, so it goes to the rear.
3. The Forward Compartment: Keep the area directly behind the motor open. This space will house Your 3S LiPo battery, and it needs room to move backwards or forwards as needs be, in order to adjust the aircraft's Center of Gravity (CG). It will be secured using Velcro hook-and-loop tape.
Then depending on the days flying, either with the heavy battery (an electric motor flight day) or a dummy weight in its place (for pure glider/bungee days)

>>> Google AI now offers this next installment.
“Lets break this down a little more and sketch out the ideal battery hatch placement, and get the final target Center of Gravity (CG) location for your test flights.”
Since you used the rubber band setup for this specific 3-in-1 combo, it keeps the build simpler, light, and gives you that rugged "crash-fuse" flexibility needed to absorb the sudden stresses of bungee snaps and javelin hand launches.
Because you chose the rubber band system, the wing will be your battery access hatch! You do not need to weaken the nose by cutting a separate door into the forward fuselage deck.
Here is the ideal internal layout and the critical Center of Gravity (CG) targets to make your 50" Mini-Soarer highly successful.

Internal Layout & Battery Access (Under the Wing, in the fuselage)
With the wing removed, you have wide-open access to the center cabin. You will want to arrange your components lenghtwise, so as to keep the nose light and clean:

[ Motor ] -> [ Firewall ] → [ ESC ] -> [ ADJUSTABLE BATTERY SECTION] (Located directly under Wing Leading Edge) -> [ Servos ] -> [ Receiver ]

* The Battery Tray
Glue a flat floor of 1/16" balsa or thin plastic along the bottom of the fuselage, starting right behind the motor and extending back past the wing's leading edge. Line this tray with a strip of hook-and-loop (Velcro) tape.
* The CG Balancing Act: Because an electric motor sits at the very tip of the nose, your plane will naturally want to be nose-heavy. To balance this out, your flight battery will likely sit further back than you expect—usually resting right underneath the front 1/3rd of the wing. This general area will be the starting point for the battery position, as we fine tune the CG

Setting the Final Center of Gravity (CG)
For your initial test flights, you want a slightly conservative, stable balance point. On Hal DeBolt gliders, the balance point is measured from the Leading Edge (LE) of the wing, moving backward toward the trailing edge.
p The Starting Target: 2-3/8” (approximately 60mm) back from the Leading Edge.

* How to Balance
Fully assemble the glider with the wing rubber-banded on, the motor installed, and the battery plugged in. Using removable marker, make a mark on each wings UNDERSIDE at the starting balance point, 1-2” out from the fuselage sides.
Next, place your fingertips under the wing on both sides of the fuselage at the marked point *exactly 2-3/8" back from the front edge.*
Lift the plane up, free of any obstructions and let it balance in your finger tips...
* Perfect Balance
The plane/fuselage should hang completely level, as viewed from the side, or with the nose pointing slightly downward (no more than 2–3 degrees).
* NEVER FLY TAIL-HEAVY
With all elctrical equipment installed, if the tail drops down when you lift it, slide your battery further forward on the tray until you reach the balance described above. Nose-heavy gliders may not fly as pretty as you'd like, but tail-heavy gliders usually fly only once...briefly.

Preparing for the Multi-Launch Configurations
Since you are switching between electric power and unpowered bungee/hand launching, you have to account for the weight difference of the battery:

1. For Electric Power Days
Strap your 3S LiPo battery onto the Velcro tray at the exact spot that hits your 2-3/8" CG mark.
2. For Bungee / Hand Launch Days

If you want to fly it as a pure glider without the battery weight, do not just pull the battery out and throw it aside. The nose will be too light, moving the CG backward into a dangerous tail-heavy condition.
Instead, you have trick the glider into thinking the battery is still there AND you have to provide a smaller battery to run the RX'r and servo's.
You see, in e-flite mode, the motor battery ALSO powers the receiver and servos through the Electronic Speed Control's (ESC) Rx'r battery eliminator circuit. Since purist-only glider flying doesn't use the motor e-flite battery, you have to replace it... while providing power for the electronics at the same time.
To make your 3-in-1 glider seamlessly transition between an electric setup and a purists unpowered glider (HLG/TLG), you need a removable dummy/receiver battery block that perfectly mimics the exact weight and physical center of gravity (CG) of your flight battery and ESC combo.

The Two Best Ways to Build It
Since pure Hand Launch Gliders (HLG) and Thermal Launch Gliders (TLG) need to be as light as possible, your goal should be to use a small, dedicated receiver battery as your new "ballas,t" rather than just dead weight.

Option 1: The "Functional Ballast" (Recommended)
Instead of putting a heavy 3S LiPo and a thick ESC in the nose on pure glider days, use a much lighter, smaller battery that doubles as your nose weight.

* The Battery: Use a small 2S LiPo (300mAh–800mAh) or a 1S LiPo/LiHv if your receiver and servos are rated for low voltage.

• The Voltage Regulator: If using a 2S LiPo, you will need a tiny micro-BEC (voltage regulator) to step the power down to 5V–6V so you don't burn out standard receiver servos.

* The Weight: Glue lead fishing weights or steel washers onto a small piece of balsa wood mounted to this battery until it matches the exact weight of your electric battery + ESC.

Option 2: The "Pure Dummy" Block (Easiest Swap)
If you want a true "plug-and-play" block where you don't change any wiring connections and just want to throw it on the slope:

* The Base: Cut a block of dense packing foam, balsa wood, or 3D-printed plastic to the exact dimensions of your electric flight battery.

* The Weight: Wrap the block in lead tape or drill holes into it to embed steel weights until the total weight matches your flight battery and ESC combination exactly.

* The Power: Glue a tiny 4-cell NiMH AAA battery pack or a tiny 2S LiPo with a micro-BEC directly into this block. When you slide the block in, you just plug this small battery into the receiver's BATT or an open channel port.

Critical Conversion Steps

When you pull out the ESC and motor battery for pure glider flying days, keep these rules in mind to protect your plane:

* Secure the Prop and Motor: On HLG/TLG days, remove the propeller blades if possible to eliminate aerodynamic drag, or, use a stout rubber band to secure the blades. If you leave the motor in the nose unplugged, tape down the three motor wires so they cannot flop around and hit the spinning rotor or short out against each other.

* Keep the CG Identical: Mark the exact Center of Gravity (CG) on the wings of your glider. When you swap between your electric battery/ESC and your dummy battery block, verify the plane balances at the exact same spot on your fingertips.

* Match it Up: Make sure that your dummy block and RX'r battery combo uses the same battery strap or velcro layout so it locks into the exact same physical footprint as the motor battery.

>> Google AI now leads into the next level...
“To ensure your 50-inch Mini-Soarer handles beautifully without being overly twitchy or sluggish, you need to set up the correct control surface throws (the physical distance the rudder and elevator move) and establish a clear pre-flight trimming routine.”
Because this model uses a lightweight 2-channel setup (Rudder and Elevator) paired with a high-torque brushless motor, small control movements go a long way.

1. Target Control Throws (The Starting Point)
Measure these deflections at the widest part (the trailing edge) of the control surfaces using a simple ruler.

- Control Surface Rates
a. Low Rate (Calm Days / Thermal)
b. High Rate (Bungee / Windy Days)
c. Exponential (Expo)

Elevator
a. 1/4" (6mm) Up / Down
b. 3/8" (10mm) Up / Down
c. 20% to 25%

Rudder
a. 3/8" (10mm) Left / Right
b. 5/8" (16mm) Left / Right
c. 25% to 30%

* Why use Expo? If you have a computerized radio, adding Exponential (Expo) in your transmitter dampens the stick sensitivity around the center point. This allows you make small, smooth corrections while hunting for thermals, but still gives you full throwing authority if you need to recover from a bad hand launch.

2. Launch Strategies & Flight Trimming
Because you have built a 3-in-1 combo glider, your throttle and stick coordination will change based on how you launch.

Mode A: The Hand Launch (Glide Test)
Before hooking up the bungee or pinning the throttle, always perform a manual test glide to confirm your trim.
* The Throw: Walk into a light breeze, hold the fuselage firmly under the wing saddle, and toss the glider straight ahead toward the horizon with a firm, level javelin stroke. Do not throw it upward.
* The Corrections
- If it immediately dives, click in a few notches of Up Elevator trim.
- If it pitches up sharply, stalls, and drops its nose, add Down Elevator trim until it tracks in a long, flat, continuous glide to the grass.
⚡ Mode B: The Electric Climb
A common mistake with downsized vintage gliders is hammering the throttle and letting the plane loop backward over the pilot's head.
Let's not do that!
* The Launch
Instead, launch the plane at 50% to 60% throttle with a straight, level hand toss. Let it build flying speed horizontally for a brief second before pulling back into a steady 30-to-45-degree climb.
* The Mix (computer radio)
Because the Soarer has a flat-bottom or under-cambered wing profile, it will naturally try to pitch up violently under power. If your radio is computerized, program a Throttle-to-Elevator mix where pushing the throttle to 100% automatically commands about 2mm to 3mm of Down Elevator to keep the climb angle straight and manageable. If not computerized, you will need to do this manually using the elevator trim controls.

Mode C: The Bungee Release
The acceleration of a mini-bungee launch is quite severe, and it happens faster than human reaction time. So you need to get it right up front...
* The Setup

Turn your radio on and ensure your transmitter sticks are perfectly centered. Hook the bungee ring to your reinforced tow-hook, walk backward until the surgical tubing is stretched to about 2 to 3 times its resting length, and hold the plane by the rear fuselage tail-boom.
* The Release
Keep your hands completely off the control sticks and launch the plane with a firm release slightly upward (about 10 degrees). Do not touch the elevator stick during the first half of the climb.
Let the velocity from the bungee pull the plane up into its natural upward arc. Only use slight rudder inputs to keep the wings level. Once the plane tops out and the ring slides off the hook, gently take the sticks and shift into your low-rate thermal mode.

Bungee Launch Final Pre-Flight Structural Checklist
Because the TLG-bungee launch puts a lot of force stress on your model, before you head to the flying field, and once there, double-check these three final details:
1. Pushrod Flex
Ensure your long pushrods running to the tail are fully supported inside the fuselage. If a thin wire pushrod can flex or bow under pressure inside the cabin, your elevator will suffer from "blowback" under the high speed of a bungee launch, resulting in a loss of pitch control.
2. Motor Prop Clearance
Spin your folding propeller by hand to verify that the blades fold back flush against the balsa fuselage sides without catching on any uneven wood edges or wiring. You may want to hold them down with a stout rubber band, since they arent used, anyway.
3. Lateral Balance
Pick the airplane up by the propeller spinner in the front, and the tip of the rudder in the back. What you are trying to do is allow the plane to rotate on its longitudinal axis. If it does, and one wing panel drops lower than the other, stick a tiny scrap of lead tape or a small screw into the opposite wingtip until the wings hang perfectly level.

>>> Next, Google AI doesn't miss much...it asked: “Do you have a computerized transmitter (where you can easily program these dual rates and elevator mixes), or a basic analog radio?”
My Response: “I expect to be using a standard analog controller.”

Building and flying with a basic analog radio is a good, traditional approach that keeps your workshop simple and completely removes the headache of navigating digital menus.
Because an analog radio cannot handle software mixes (like pushing down-elevator automatically when you advance the throttle) or electronic dual rates, you must do it yourself, and, build the proper aerodynamics directly into the airframe itself.
Here is how you mechanically tune your 50" Mini-Soarer to fly safely and stably on a basic analog transmitter:
───

⚙️ 1. Setting the Control Throws – Mechanical Rates
Without a programmable computer to reduce your throw percentages, you must use the physical geometry of your servo arms and control horns to set your maximum deflections... in others words, do it the old-fashioned way.

[Servo Rudder/Elevator Arm] - O O O X <- Inner Hole (Low Throw)
(Center Spline) (Hinge Line) →
[Rudder elevator Control Horn] → 0 0 X <- Outer Hole (Low Throw)

* For Smooth, non-Twitchy Flying
To have a smooth, forgiving flight, you actually want to reduce the controlling movements of the rudder and elevator. To do this, attach your pushrods to the innermost holes on each servo arm (closest to the center screw) and each to the outer/uppermost hole on the rudder/elevator control horn.
The Physics
This set-up – reduced servo throw and reduced control horn movement – changes the mechanical leverage (or moment arms in engineering talk).The effect is to make the servo push the control rod less, with reduced mechanical force and resolution felt at the control surface. Changing the pushrod location at either end – servo arm or control horn - will conversely make the movements greater and increase their effect o nthe model. In other words, you will have a more twitchy model.
But with the smooth settings as described, even if you slam the transmitter stick all the way to the edge, the control surface will only deflect a small, gentle amount (aiming for that 1/4" to 3/8" range we discussed). Once you are proficient at launching and flying, you can start increasing the control throws for more performance.

2. Beating the Balloon Effect (Thrust Angle vs. Throttle Mix)
As mentioned before, flat-bottom glider wings tend to "balloon" (pitch up sharply into a dangerous loop) when an electric motor spins up. Since you don't have a digital Throttle-to-Elevator mix to fight this, you must resolve this by builfinh in the proper with Mechanical Motor Thrust Angle.
* The Fix
When gluing your 1/8" plywood firewall into the nose, intentionally tilt it downward by 3 to 4 degrees and to the right by 1 to 2 degrees.
* How it works
When the firewall is set in place this way, as you throttle up, the motor will tend to physically pull the nose of the glider slightly downward – which offsets the wing's natural urge to pitch up. When you cut the throttle to glide mode (aka, “OFF”), the motor stops pulling the nose down, and the plane will seamlessly transition into a flat, efficient gliding posture.
Remember, this downward pitch is only for the motor run scenario. When the motor is out of play (not running or not being used), the slight downward pitch has no effect.

3. Handling the Bungee Launch on Analog Radios
Because you cannot flip a switch for "Launch Mode" or use exponential smoothing on an analog stick, a bungee launch requires old-school pilot discipline. Remember, long before computerized radios were a thing, RC pilots successfully managed this evolution – so you can do it!
The Golden Rule

“Thumbs completely OFF the sticks during the launch stroke.”

The Launch
When you release the plane on the bungee, your spring-loaded analog sticks must be perfectly centered. Then, let the airplane fly itself off the rail. The inherent stability of Hal DeBolt’s polyhedral wing design should tend to keep the plane straight.
If neccessary, say, should a gust of wind try to tip a wing, just make tiny, gentle corrections on the rudder stick. Don't touch the elevator until the plane naturally levels out at the absolute peak of the launch and drops the towline.

4. Final Mechanical Check
Since you don't have digital sub-trims to center your surfaces...
Turn on your transmitter and plug in/switch-on the flight battery so the servos jump to their absolute mechanical center. Make sure the control sticks are also centered, with the trims at zero
Now, adjust the metal clevises or screw-stoppers on your pushrods by hand, until the rudder and elevator trailing edges are perfectly flush and inline with the stabilizer fins. Tighten the locknuts securely so nothing can slip, mid-flight.

BUILDING NOTES FOR STICK BUILT MODELS

The absolute easiest and most accurate way to duplicate 15 to 20 identical balsa wing ribs by hand is the "Sandwich" (or Block-Sanding) Method.
Instead of painstakingly cutting out 20 individual ribs with a razor blade — which always leads to slight shape variations — you stack ip a bunch of balsa blanks, clamp them together between two durable templates, and shape the entire wing's worth of ribs all at once.
Here is the step-by-step process to get perfectly uniform ribs for your 50" Soarer:

Step 1: Make Two "Master" Templates
Because you are shrinking a printed sheet, your templates need to be tough enough to withstand a sanding block.
Step 1.
Cut out the downsized rib drawing from your printed plan sheet, leaving a small border around it. Use a glue stick or spray adhesive to paste the paper rib onto a scrap piece of 1/16” or 1/8” aircraft plywood. (Other things like 1/16” aluminin sheet or even an old plastic credit card/gift card can work – aluminum is nice because it can be used again and again).
Carefully cut out this master template using a scroll saw, coping saw, or heavy utility knife, and sand the edges until they are perfectly smooth. Now do it again - make two identical master templates (one for each end of your sandwich stack).
Step 2: Prep the Balsa Blanks
1. Cut your 1/16" rib balsa sheet into rectangular "blanks." Each rectangle should be just slightly longer and taller than your rib template.
Cut enough blanks for your entire wing (e.g., if your wing needs 18 ribs, cut 18 blanks).
Step 3: Build the Sandwich
1. Stack all 18 balsa blanks neatly on top of each other.Place one plywood master template on the very top of the stack, and the second master template on the very bottom.
Next, drive two long pins, thin nails, or wood screws straight down through the entire stack (from the top plywood template, through all the balsa blanks, and into the bottom template). Some people use a little removable adhesive, like Post–A-Note glue to help hold everything titghtly. This locks the sandwich together so nothing can slide out of alignment while you work.
Step 4: Sand to Shape
1. Clamp the entire sandwich block into a bench vise, or hold it firmly against your workbench.Use a razor blade or hobby knife to rough-cut away the excess balsa corners that stick out past the plywood profile.
2. Take a long, flat sanding block with 120-grit sandpaper and sand down the balsa edges until your sandpaper flushes up perfectly against the hard plywood templates. Because the template is harder than the balsa, your sanding block will naturally stop cutting once it hits the master template shape. Now, switch to 220-grit sandpaper for a final smooth finish.
You can also use a disc sander but you must be very careful not to over do it. The hand method is probably safest.
Step 5: Cut the Spar Slots (The Secret Trick)
While the sandwich is still pinned together, look at the spar locations on the top template:
1. Use a razor saw or a small hand-held hacksaw blade to cut the vertical edges of your spar slots straight down through the entire balsa block at once. Use a scrap piece of your actual spar wood wrapped in sandpaper to clean out the bottom of the slots. This guarantees that your main spar will slip perfectly into every single rib across the entire wingspan without any misalignment.

The Final Reveal
Pull the pins out and separate the stack. You are left with a pile of perfectly identical, match-grade wing ribs that are ready for assembly in a fraction of the time it would take to cut them out one by one.

To The Build, And Beyond...
The absolute best, cheapest, and most traditional flat building surface that will not warp your wings is a 2' x 4' sheet of acoustic ceiling tile placed on top of a flat workbench, or a hollow-core interior door.
To build a straight balsa wing, you need a surface that is dead flat so the structure doesn't twist, but soft enough that you can easily push T-pins into it to hold your balsa ribs and spars in place.
Here are the two best low-cost methods used by balsa builders:

Method 1: The Acoustic Ceiling Tile (Cheapest & Most Versatile)
Go to a local home improvement store (like Home Depot or Lowe's) and buy a single 24" x 48" acoustic ceiling tile (the kind used in suspended office ceilings). They usually cost under $10.
* Why it works: The white, textured front side is okay, but the smooth back side (the brown, unpainted fibrous side) is perfect. It is incredibly flat, and standard hobby T-pins slide into it smoothly but hold tightly.
* The Setup: Simply lay the tile flat on top of an existing table, workbench, or kitchen counter. If your table is slightly uneven, place a piece of 1/2" plywood or MDF under the tile first to give it rigid backing.

Method 2: The Hollow-Core Door (The Ultimate Portable Bench)
If you don't have a dedicated workbench and need something you can lean against a wall when you aren't building, buy a cheap hollow-core interior door slab (a closet door with no handle holes). You can often find these at hardware stores or home salvage yards for $20 to $30.
* Why it works: Because of their internal honeycomb structure, hollow-core doors are engineered to stay completely flat and resist twisting or warping.
* The Setup: Lay the door across two sawhorses or flat tables. Then, tape your printed 50" Soarer plans directly to the door. Since the outer veneer of a door is wood, it can be slightly tough to push pins into directly—so builders usually tape a sheet of corrugated cardboard or a ceiling tile right on top of the door to act as the pin-cushion.

Two Crucial Rules for Wing Building
1. Protect the Plans
Balsa glues (like CA or wood glue) will bleed right through your balsa joints and permanently glue your wing to your printed paper plans. To prevent this, always cover your printed plan sheet with a layer of wax paper, clear kitchen plastic wrap (Saran wrap), or backing paper from iron-on film before pinning wood down. Glue will not stick to these.

2. Pin, Don't Hold: When assembling your sandwich-cut ribs onto the main spar, never hold the parts in your hands while the glue dries. Pin the bottom spar flat to the board, slide the ribs on, pin the ribs down so they sit at a perfect 90-degree angle to the board, and only apply glue once everything is locked flat. Using a 90 degree angle block to ensure the rib is perfectly upright is good insurance. Leave it pinned until the glue is 100% cured to prevent built-in warps.

GLUES
Cyanoacrylate (CA) and epoxy are the perfect two-glue combination for this, or any, balsa project. CA keeps the build fast and ultra-lightweight, while epoxy provides the brute muscle needed where the extreme forces of bungee launches and motor torque concentrate.
Because weight is the ultimate enemy of a 50-inch glider, using these two glues strategically will keep your airframe incredibly strong without turning it into a heavy brick.

⚡ 1. Cyanoacrylate (CA) Glue Strategy
Use CA for 90% of the airframe. It wicks into balsa joints instantly and adds almost zero weight when used properly.
* Thin CA: Best used after parts are already pinned together. Position your sandwich-cut wing ribs over the main spar, ensure everything is square and pinned flat to your ceiling tile board, and touch a tiny drop of thin CA to the joint. It will instantly wick deep into the wood grain.
* Medium CA: Best for joints that have slight gaps or for gluing fuselage formers to balsa sides. It gives you about 5 to 10 seconds to slide parts into position before locking up.
!! The Weight-Saving Secret: Never squeeze CA straight from the bottle onto delicate balsa joints. Use fine Teflon applicator tips (extension tubes), toothpicks, or plastic slivers. A good precision applicator can be made from large sewing needles with the top of the thread eye cut off, This creates a “Y” that hold glue and allows fro precision placement.
These metjods allow you to apply a micro-dot of glue exactly where it's needed, in just the right amount. A sloppy-built model made straight from the bottle and nozzle, often ends up ounces heavier than one built with precision tips and/or applicators due to excess glue buildup.

2. Epoxy Glue Strategy
Epoxy is heavy, so you should use it sparingly. Reserve it exclusively for the, "high-stress zones," where CA is too brittle to handle the vibration and impact forces of landing, bungee pulling, or motor thrust.
Use 15-minute or 30-minute epoxy for these critical areas (avoid 5-minute epoxy if possible, as it cures more brittle and breaks down faster over time)
* The Firewall: Use epoxy to glue your 1/8" plywood firewall into the nose. The vibration and forward pull of your brushless drone motor will easily shatter a brittle CA joint.
* The Tow-Hook Block: The 1/4" plywood or hardwood block holding your bungee hook must be epoxied securely to the fuselage floor and sides. A bungee launch applies immense tension; epoxy distributes that load evenly across the wood fibers.
* The Wing Center Joint: When you glue the two halves of your 50" wing together at the center dihedral angle, butter the joining root ribs with epoxy. Once dry, use a little more epoxy to laminate that 1-inch fiberglass cloth strip neatly over the center seam.

Essential Building Tips for This Combo
1. Keep Kicker / Accelerator Use To A Minimum
If you use CA accelerator spray to speed up your build, spray it very lightly. Using too much kicker can cause CA to cure instantly into a foamy, brittle white crust that is actually weaker than a naturally cured joint, and it can stain or warp thin balsa.
2. Scrape Away Epoxy Squeeze-Out
When clamping your firewall or tow-hook block with epoxy, use a scrap piece of balsa or a paper towel dampened with a tiny bit of rubbing alcohol to wipe away any excess epoxy that squeezes out of the joints. It doesn't add strength to the joint if its outside the joint, and it's just dead weight.
3. Sand Your Joints Flush
Before you cover your finished, pinned-and-glued structure with your transparent covering material, use a long sanding block to lightly sand all the CA joints flush. This removes hard, high spots of glue that could pierce or ruin the clean lines of your film.

CLOSE
AI Google had this to say at the end:
“It sounds like you have a fantastic project ahead of you with this 50-inch "Mini-Soarer" conversion. Balancing the classic Hal DeBolt lines with modern electric and bungee capabilities on an analog setup is going to result in a truly rewarding build and a beautiful flyer.
Take your time pinning everything flat to that ceiling tile, keep that epoxy focused strictly on the high-stress areas, and enjoy every bit of the building process.
Blue skies and happy landings with your new glider! ✈️
If you run into any more questions while assembling the airframe, balancing the CG, or rigging up your custom mini-bungee, just drop back by.
Good luck with the build!”