How To Repair Balsa Rc Plane

Written by Mark Wilkins Giving a Pup a 2nd chance Feature As seen in the March 2017 upshot of Model Aviation.

Using a sharp paring chisel, advisedly carve abroad the old balsa longerons. Take care to scrape away erstwhile glue because information technology volition compromise the new articulation.

All that was salvageable from the author's old Pup fuselage was the nose section, which held together well.

I t happens. We've all been there, flight blissfully effectually our field, hotdogging and doing every stunt in the volume. The time slips by, flight later flight, and a nagging vocalism in the dorsum of our mind tells united states to check our flight battery pack.

The heaven is so blue and the wind is so light—just ane more flight … or perhaps we are flight late in the twenty-four hour period and the shipping silhouette is such that nosotros lose orientation, or perhaps it is a uncomplicated instance of dumb thumbs. Whatever the reason—or lack thereof—the result is the aforementioned. The airplane goes downwardly.

With a heavy eye, yous get together the pieces and tell yourself that it is non that bad and information technology can be stock-still. The skillful news is that information technology tin, and sometimes you'll terminate upwardly with an airplane that is better than it was before.

After a model crashes, it's a practiced idea to fix it aside for a few days or even weeks. This does a few things. The emotional aspect and discouragement fades (y'all finally end calling yourself an idiot!), and you are able to approach the repairs with a fresh, positive attitude.

Now, take a good look at the wreck. You'll probably observe things now that you missed when you brought it home from the field. Keep an eye out for areas of torn covering that can indicate fractured framing that isn't readily visible. Check all of the major joints—e.g., firewall, fly roots, places where two wing panels are joined, etc. You'll develop a list of repairs and go a better sense of what's involved.

New basswood longerons were fitted into identify against the turtledeck and other framing for alignment.

A new side panel was built over the original plans using basswood longerons. A fractional wing saddle was incorporated into the side panel, designed to be joined to the original wing saddle on the forward portion of the fuselage.

The old meets the new: a close-up of the half-lap joint betwixt the original and new lower wing saddle.

The aft ends of the fuselage were cemented using epoxy. The crossmembers are not fitted betwixt the fuselage side panels.

Most repairs aren't that difficult and knowing when to rebuild and when to discard is what matters most. Earlier undertaking an involved repair task, ask yourself a few questions.

Did the airplane really fly so well that a potentially lengthy rebuild is justified? Are the repairs within your ability? Are spare parts—be it die-cut formers or entire airframe components—bachelor for my aircraft?

If information technology is a favorite ARF model and it'due south the middle of the flying flavour, sometimes it is merely easier to buy a new fuselage, wing panel, or set of landing gear if your upkeep allows. If the blow occurs at the terminate of the flying flavour, well, you have plant a winter projection! Such was the case with my ⅙-scale Balsa United states of america Sopwith Pup.

Prelude to a New Fuselage

This aeroplane flew well and I desperately wanted information technology back in the air as soon every bit possible. The wings were basically in okay shape, only the fuselage aft of the engine/fuel tank area was gone. I ever keep the plans for the models I build, so I pulled them out and prepared to build new fuselage side panels.

Earlier doing this, I needed to remove whatsoever trace of the erstwhile longerons, which I achieved using a pocket-size paring chisel. I used a scrap of new longeron material to exam fit the slot where the new fuselage longerons would mate with the intact nose section and turtledeck.

I fabricated sure to scrape away all of the old glue to ensure a good bond. When I was satisfied, I fitted the new longerons into place to check the alignment.

Additionally, I removed all of the servos, the fuel tank, and the receiver from the fuselage nose section and set up them aside. While I waited for glue to dry, I checked the flight components for damage and replaced them as necessary. Oft when a model makes a sudden stop (crash), the command surfaces are whipped in one direction or some other. Be sure to check these servos, particularly the all-important lift servo(s).

The new aft turtledeck stringers were cemented onto new formers. Check to be certain these stringers are straight by sighting down them. Too check them from the sides to ensure that there are no humps or hollows.

Exam fit the lower fly to the new wing saddle.

A New Fuselage

The side sections were built over the plans the aforementioned way as the original fuselage was built, but this time I substituted basswood longerons (spruce would exist fifty-fifty better) to make a sturdier fuselage. A new partial lower wing saddle was built into the side panels and would join the nose department by ways of a one-half-lap joint. After the sides had completely stale, I advisedly fitted them to the onetime nose section to bank check and adjust the fit. When I was satisfied, I epoxied them into place.

When everything was dry, the emerging fuselage was carefully positioned over the peak view of the plans and pinned securely to ½-inch foam core beneath the plans. Next, the ii sides were carefully brought together using squares to ensure perfect alignment relative to the plans. Crosspieces were fitted and cemented into place, checking the fuselage frequently to ensure that no twist was being introduced.

Aft turtledeck formers were fatigued onto tracing paper, which was in turn rubber cemented to cardstock and cut out, yielding templates to brand new formers. The formers were fabricated from medium balsa and cemented into place.

If you don't want to bother with this, some companies such as Balsa Us offer replacement die-cut balsa or plywood sheets for roughly $5 each. Find the instruction canvas with the formers on it and make a telephone call. Hard balsa stringers were positioned with pins in the formers, checked to ensure that they were directly, then cemented.

Tail Skid and Gussets

The original tail skid was a prebent piece of wire supplied in the kit. It worked well and lasted a long time. Because I was rebuilding the fuselage anyhow, I decided to give the Pup a shock-arresting tail skid setup with a bungee. I made two lite plywood plates through which an beam was passed.

The tail skid was fabricated from basswood and a brass bushing was epoxied through it. I slid the finished unit of measurement into identify. An axle was passed through the two plywood plates and the tail sideslip's bushing and was secured. You tin can bend i end to course an L and secure the free end with either a bicycle collar or a soldered washer.

A plate with a hole drilled in it was epoxied to the stop of the fuselage to serve as an anchor for the bungee. As a reinforcing measure, I made plywood gussets from one/32-inch shipping plywood and glued these to all of the joints inside the fuselage. Where applicable, these were notched to receive the crossmembers.

A new tail slip was made from scrap basswood and light plywood. A plywood plate with a pigsty bored through was epoxied to the inner rudder post and serves equally an anchor for the tail skid bungee.

Aircraft plywood gussets or backing plates were glued over all of the major joints in the fuselage framing.

The fuel tank and servos take been returned to the fuselage.

The fuselage is being covered with Linen Solartex.

Checking the Fit of the Tail Feathers and Bottom Wing

Afterwards the fuselage has been completed, it is time for a reward: checking the fit of the tail feathers and lower wing. The basswood lower wing mounting plate (through which the nylon bolts were passed) was intact; however, the portion of the old wing saddle to which information technology was attached was destroyed. I needed to carefully fit the old mounting plate into new notches in the new fly saddle.

Fortunately for me, I had measured and cut the notch accurately and the wing lined up well when the distance betwixt the wingtips and the cease of the fuselage was checked. If demand be, nibble away the notch until your lower fly and plate are perfectly aligned, so liberally epoxy it into place. W Arrangement or 2-Ton epoxy would exist my selection.

After the lower wing has been successfully reinstalled, bank check the alignment and fit of the stabilizer and rudder relative to the lower wing. Shim or adapt as necessary to ensure that the stabilizer is parallel to the lower wing, and the rudder and fin are perpendicular to the stabilizer/elevator associates.

Reinstalling the Linkages, Servos, and Receiver

With the fuselage completed, reinstall the servos, pushrods, fuel tank, and receiver. I decided to install the satellite on my Spektrum 6210 receiver for added insurance. I also relocated the receiver further aft; I like to go on my receiver well away from the servos to prevent interference. The satellite was mounted with its antenna perpendicular to the run of the primary receiver antenna, per the instructions.

Finishing the Fuselage and Reassembly

With the gear securely reinstalled, I covered the finished fuselage using Linen and Olive Drab Solartex. Later I completed that, I reinstalled the engine, aluminum cheek, and summit cowling panels. Roundels were painted on the fuselage using acrylic paints, and the entire unit was thoroughly cleaned and given two coats of Minwax spray polyurethane for protection from glow fuel.

The wings and tail feathers were reattached to the fuselage, paying particular attention to the alignment of the lower and upper wing. With biplanes you desire this alignment nearly perfect. Forcing the wings into alignment volition often cause an unwanted twist in the wings.

New British roundels were painted on the fuselage using masks and acrylic paints.

The Olive Drab Solartex aft turtledeck covering was carefully applied and trimmed to fit, and and so the airframe was reassembled.

Test Flight

The test flight went off without a hitch and this Pup has shrugged off its shame and returned as the queen of the skies that it truly is. This repair took approximately a week, working function time, and I was able to comprise improvements such as the basswood longerons, working tail skid, and receiver satellite.

This is possibly the all-time fashion to view a repair—if you're going to go to the trouble of doing it, y'all might every bit well build in some improvements while you're at it.

—Marker Wilkins markcwilkins@gmail.com

SOURCES:

Balsa USA

(800) 225-7287

world wide web.balsausa.com

Minwax

(800) 523-9299

www.minwax.com

Source: https://www.modelaviation.com/aircraft-repair-wilkins

Posted by: lealayed1960.blogspot.com

Share this post