Quick and Easy ARF Landing Gear Repair

Oct 29, 2013 6 Comments by

It happens all the time and I think, damaged landing gear from landing “Off Field” is probably the single most common repair needed sometime during a RC model’s lifespan. We recently were test flying the new 30cc Ultimate Biplane from Aeroworks and an Engine Out on the downwind gave us a great case of Landing Gear Grown!

tall grass   IMG_8389

Test Pilot and MAN contributor Aaron Ham was doing an inverted pass when the plane went “Dead Stick” heading downwind and too low for a safe 180 turn. So he settled the plane into the tall grass at the end of the runway with a broken prop and badly “Tweaked” landing gear for his trouble.

Here’s some tips to make this all too common repair, it can be done on various other ARF models with bolt on landing gear.

IMG_8391

The Damage isn’t terrible but to do a proper repair you have to first examine the plane and remove all the damaged parts.

IMG_8398

Unbolt the gear and use a tray or pan to keep all the hardware and screws together so you don’t lose anything or have it get under your plane to cause hangar rash!

IMG_8395

I always like to use a foam work stand like the ones from Robart Mfg.

IMG_8393

Of course since the propeller is also busted, remove the cowling and check the engine, firewall and engine mount.

IMG_8405

Once the gear and engine cowling is removed, you have to remove the covering. Use a Covering Heat Gun set on high to heat the covering. It will over heat quickly and begin to lift up from the wood. Peal it away and when you get to the undamaged parts of the sides, use a sharp hobby knife to make clean cuts in the covering so you can make straight repair seals.

IMG_8406

If you have any fuel dots or drain/vent fittings, simply remove the fuel lines and remove them and the surrounding sheeting.

IMG_8413

Clean off any glue and you can reuse the fittings

IMG_8418

Remove all the damaged sheeting with a sharp hobby knife.

IMG_8425

As you remove the damaged wood, be sure to inspect the internal structure and make sure that there are no other damaged parts deeper in the fuselage and that all the glue joints are sound. Here you see the aluminum support angle that ties the landing gear to the internal structure.

IMG_8438

Remove the rest of the damaged sheeting from the repair area. I find a razor plane works great for removing cracked and split sections of wood from the underlying structure.

IMG_8429

Remove the broken landing gear attachment plate and set aside.

IMG_8434

Finish cleaning up the underlying structures and sand the edges smooth with a sanding bar. This will allow the new balsa sheeting to make a strong bond.

IMG_8431

To maintain the proper bolt spacing, bolt the damaged parts of the landing gear plate back into place and glue them together. This gives you an accurate template for making the replacement plate. After the glue dries, remove the old plate.

IMG_8440

Place the old plate over some 1/8 inch Aircraft grade plywood and trace its outline. Accurately transfer the outer bolt hole locations as well.

IMG_8442

Cut the new plate out with a band saw then use a belt sander to smooth out the cuts to the pencil guidelines.

IMG_8444

Sand the ends to the proper length and angle to match the fuselage sides and then drill out the bolt holes on either end of the new plywood plate.

IMG_8447

IMG_8450

Test fit the new plate and lightly bolt it into place to make sure the bolts align with the threaded parts of the underlying metal angle supports. If there is a light misalignment, you can drill a slightly larger hole fto provide clearance.

IMG_8451

Bolt the landing gear in place as show above and use a straightedge stick to make sure the gear are straight and square to the fuselage centerline. Once they are properly aligned, tighten the two outer bolts and then drill out the inner bolt holes. Then trace the base of the gear.

IMG_8452

Here’s the final bolt holes and gear guide lines.

IMG_8454

Now use the new plate and trace out a lite ply spacer to form the recesses the landing gear will fit into after the repair is complete. You also have to add a little extra length to the spacer piece so it overlaps the fuselage sides.

IMG_8455

Cut away the center section the gear will fit into and use a sanding stick to clean up the cutouts to fit the gear.

IMG_8456

Carefully glue the spacer on top of the plywood plate aligning the openings with the guidelines you previously drew on the plate. Red Baron Adhesives Medium CA and accelerator is being used here. Make sure not to get any glue inside the recess area.

IMG_8463

Use the cutaway part of the lite ply spacer and glue to the underside of the plate centered on the inner attachment bolts holes. Drill out the holes and then install blind nuts for the inner landing gear bolts. For this plane the bolts are 6-32 cap-head machine screws so 6-32 blind nuts from the hobby shop are being used. I used a plastic face dead-blow hammer to set the blind nuts into place, and then I use medium CA to secure the wings of the blind nuts. be sure not to get any glue in the inner threads.

IMG_8466

Using the outer bolts secure the new gear plate to the fuselage, applying adhesive to all the mating surfaces. Red Baron Adhesives’ CA make excellent bonds to metal and wood, but use only a small amount so it does not get into the threaded areas. Properly glued into place, the top of the lite ply spacer should be flush with the top of the surrounding structures.

IMG_8472

Cut the new balsa sheeting to size (I used 3/32 inch sheeting), and glue it into place, Leave a small space between the edges of the landing gear bases and the edge of the sheeting. A good way to make neat gue joints is to apply the glue to the model and then spray the accelerator to the underside of the sheeting. Then place the sheeting into place and hold for several seconds until the adhesives cures. After the large sections are glued in place, cut the center sheeting piece to size and glue it in place between the landing gear bases to form the finished  recessed areas.

IMG_8473

Remove the landing gear and this is what you are left with. Scrap balsa sheeting will be used to fill the gaps.

IMG_8475

Cut the scrap to length and glue into place with thin CA glue.

IMG_8476

Sand the scrap flush with the fuselage side and then sand the corners round with a sanding block. Use 100 grit sandpaper then finish sand with 220 grit until everything is nice and smooth.

IMG_8481

Apply some model filler ( I like Hobbylite filler from Hobbico,) and fill any gaps or defects in the glue seams and let dry.

IMG_8485

 

Use some 220 grit sandpaper and smooth out the filler. The model’s repair area is now ready to be recovered.

IMG_8399

Before reinstalling the landing gear, now is a good time to clean them up and to check for any damage or loose screws needing to be taken care of. It is eaier now than when they are reattached to the model.

IMG_8493

Clean off any sawdust and clean the fuselage covering with some solvent to properly degrease the surface then iron on some new covering material that matches the model’s finish. Start from the center of the repair area and work outward pulling out the wrinkles as you go. Take your time and make all your seams straight and neat. Now bolt the landing gear back into place. If your hardware is bent or damaged, replace with new bolts and washers.

IMG_8495

A neat and quick way to make the holes for the fueling fitting and drain/vent, is to use a sharpened piece of brass tube. Bevel the inner edge with a sharp hobby blade and sharpen the outer edge with fine sandpaper. Press the tube cutter against the model and push firmly with a twisting motion to cut the hole. Side the tube cutter diameter to match your fittings.

IMG_8498

Reattach the fuel lines to the fittings and use thin CA glue to secure the fittings within the new holes.

IMG_8501

Add a little lock-tite thread locking compound to the landing gear attachment bolts and tighten them securely into place. That’s it! Reinstall your engine cowling, stick a new, properly balanced prop back on your model, reinstall the spinner and you’re ready for your next takeoff!

Uncategorized

About the author

Senior Technical Editor About Me: I have a lifelong passion for all things scale, and I love to design, build and fly scale RC airplanes. With 20 plus years as part of the Air Age family of magazines, I love producing Model Airplane News and Electric Flight.

6 Responses to “Quick and Easy ARF Landing Gear Repair”

  1. David Naismith says:

    Great repair how-to. I expected a beefier replacement, rather than1/8″ without full (fuselage) width support piece.

    • Gerry Yarrish says:

      1/8 inch aircraft grade plywood is a lot more tougher than the stock Lite Ply plate that gave up the ghost. Also, the aluminum angle pieces tie the gear to the internal plywood formers so it is plenty strong now. Remember, don’t just add weight, add strength with careful selection of repair components.

  2. otto derr says:

    I wish they used wire instead of fixed gears, lots more give. Otto Derr

  3. Lawrie Henrickson says:

    I use nylon bolts to attach my landing gear. The bolts hold fine in normal landings, but shear in an unplanned arrival. Easily removed and replaced. Sure beats the effort required with this kind of repair job (which was of very high quality).

  4. JACK DE LORME says:

    WHY NOT USE A ONE PIECE LANDING GEAR MUCH STRONGER,
    NYLON BOLTS ,THE GEAR BRAKES
    OFF AND TEARS YOUR TAIL OFF, I KNOW. JACK

Copyright © 2014 Air Age Media. All rights reserved.