FlyingRC.net is a
Veteran-Owned site.

One thing you can count on in RC flying is sooner or later something goes wrong and you fail to miss the Earth. In this story I show you how I rebuilt the 10cc Valiant after such an episode. Click image to enlarge

Repairing Hangar 9 10cc Valiant Crash Damage

I stuff one in the ground just to show you how I fix it - Honest

Text, photos and video by Tom Hintz

Flight Video by Clark Ponthier

Posted - 4-3-2018

I was warned early on that my “warts and all” philosophy behind the running of my web sites would open the cyber-door for condemnations from the ever-growing legion of self-proclaimed “Internet experts”. When I posted the video of me flying the Hangar 9 10cc Valiant into the ground I discovered that advice was true – and under-stated. To date (4-2-2018) I have 40-some different “exact” reasons for my crash, all from folks with the magical ability to divine the real error of someone’s problem irrespective of the facts.

Over the last 15 or so years I have built up a tolerance against being admonished by these masters of misinformation and have grown immune to their holier-than-thou bursts of ego. However, I remain concerned when these “experts” go after someone who is relatively new to RC flying. If they are anything like I was in the early days of my RC life, filtering out the baloney issued by these “experts” can be difficult and potentially expensive.

ARF Complications

The dominance of ARF (almost ready to fly) kits has created an ever-growing number of RC flyers who have never stick-built a RC plane. That’s not a knock on them just the direction the RC world has gone over the years. Modelers with decades of plane-crashing and stick building under their belts can use that experience to repair sometimes terminal-looking damage. Newer hobbyists may have fewer options.

Crashing nose first can look terrible (left) but can turn out better than you think. In this case only the fuselage needed to be replaced (right) which brought the repair in at around $90! Click images to enlarge

The damage to the Hangar 9 10cc Valiant was concentrated in the fuselage so buying a replacement fuse fixed the damage and was the cheaper than buying a new kit by quite a bit. The fuselage cost, $89.95 (2-22-2018). I also needed a wing tube but those were out of stock. However, I measured the outside diameter (5/8”) of the crash-bent wing tube and found “off the shelf” aluminum tubes in that diameter that cost me just under $5 for a pair (packaged in pairs), about half of $8.99 (2-22-2018) that Hangar 9 gets for one.

Initial Radio Check

The first thing I do following a crash is to turn the radio gear on, transmitter first and then the plane radio system second. While I check everything I can, first up is a range check done outdoors. The Hangar 9 10cc Valiant on-board radio gear range checked perfectly before and after the crash at much greater distances than is considered sufficient. Plus, I had no feeling of losing radio contact during the crash, so I decided to use the same radio gear in the rebuilt Hangar 9 10cc Valiant.

All the Hangar 9 10cc Valiant servos worked properly during this post-crash check and none appeared to have damaged gears despite my “being stupid” (according to a few Internet wizards) for using these servos in the first place. This is my first plane in 30-some years using the recommended servos and might not be the last considering how well they held up to the crash.

It’s the Sequence Stupid!

One of the liabilities of the high-wing design is the tremendous force that can be applied to the upper cabin structure when a wing tip contacts the ground. The fact that the Hangar 9 10cc Valiant wing torqued the top of the fuse off without damaging either wing panel was not surprising. It also proves the utility of all that leverage stuff my high school science teacher was trying to teach me while I was more focused on a car or girl.

When the Hangar 9 10cc Valiant went in, it appeared to hit on one wing tip and the spinner almost simultaneously. I had pulled the throttle back to idle well before it met the Earth, reducing airspeed somewhat before the crash. Luck and realizing the “hit” was imminent helped reduce the overall “mooshing”. Another favorable aspect of this crash was the rain-soaked ground surrounding our flying field. That soggy farm land (loose, wet dirt) did a great job cushioning the impact, particularly the force delivered to the engine. The propeller lost one blade, plastic spinner got dirty and the cowl showed signs of over-flexing, but it is useable until they are back in stock.

ALWAYS check the clunk weight (left) after a crash to be sure the tubing has not folder forward! Skipping this simple check has killed a bunch of airplanes! I always look around the mounts for things like the carb (right) and muffler, looking for distortions. Click images to enlarge

Fuel System Always

Removing the fuel tank is second in my sequence in part to get the fuel out of the way. However, regardless of how severe the crash was we need to look at the tank and fuel lines closely for “blunt force trauma” (Can you tell I am a NCIS fanatic?) as well as other internal problems inflicted by what can be surprisingly high deceleration forces.

The weight of even a partial fuel load can cause the tank to lurch forward with sufficient force to pinch/cut lines against the planes structure. Also, if the pickup clunk is on flexible tubing, as most are, the pickup line can fold forward in surprisingly “small” crashes. Not checking this clunk position is a great (and frequent) way to dead stick a freshly-repaired plane into another crash. Taking the tank apart to check the internal components is always worth the effort.

Engine Inspection

Engine-related parts of particular concern are those bolted to it like the carb and muffler. Both extend out from the crankcase enough that relatively small impact forces can bend or break them. In the Hangar 9 10cc Valiant crash the rather low speed and rain-soaked ground combined to spare the NGH GT09 Pro 9cc Gas Engine. There was no visible damage, and no packed-in dirt so the NGH GT09 Pro 9cc Gas Engine went into the new fuselage and performed fine later when the Hangar 9 10cc Valiant went airborne again.

Wings

Virtually any crash is reason enough for a close inspection of the wings. Having seen the wing contact the ground during this crash had me twisting and flexing each panel looking for internal breaks. The root ends of both wings showed no damage around the wing tube sockets. I did note that one wing still had the retaining bolt and the structural member from the top of the cabin attached. The “softness” of that cabin structure appears to have saved me a set of wings.
I did find one flap had three broken pin hinges. I tried to work the broken hinges free, but my hinge epoxy technique had the hinges locked in place, so I drilled holes for new pin hinges (same size) next to the broken ones. All things considered, three pin hinges are a small price to pay to rebuild this part of the Hangar 9 10cc Valiant.

When we first looked at the crash damage I thought it was a gonner (left) but after looking closer realized just the fuselage had to be replaced. The tail feathers survived (right) and were transplanted to the new fuse. Clicki images to enlarge

Fuselage

In the case of the Hangar 9 10cc Valiant crash, it was obvious that the fuselage was a gonner, for me anyway. I know people that can do this kind of repair without losing a bunch of structural strength or adding weight (those two go together) but that isn’t me. For me, the cost of the new fuselage was short money for rebuilding the Hangar 9 10cc Valiant. That cost is also a good way to “fine” myself for the crash.

Tail Feathers

The good thing about this nose-down crash is that the tail feathers survived. Because the back section of the Hangar 9 10cc Valiant remained untouched I was able to literally bust/cut the tail feathers out of the junk fuse, clean them up and install them on the new fuse.

As during the initial assembly, I took the time to align the horizontal stabilizer with the wing tube. This is a crucial step towards getting a good flying plane whether it’s a new build or a resurrection. I also had to cut the bottom CA hinge on the rudder to separate it from the old fuse. A new slot was cut along the side of the original CA hinge and the new one glued in place after the tail feather assembly was aligned.

Ready and Waiting for the Re-Maiden

After going through the control surface setups and confirming they were going in the right direction the resurrected Hangar 9 10cc Valiant was ready for the re-maiden flight. From this point on there is nothing that differs from the first maiden other than I will not fly it in big wind, at least until I get it trimmed out. As always, the pilot is the biggest threat to modern RC aircraft, new or rebuilt.

It took longer than I wanted to get to the re-maiden flight, but a long series of rainy, cold weekends made me wait. But, we finally got a marginal (wind again) flying day but decided to suck it up and fly this thing! Watch for the Re-Maiden story coming shortly!

Resources

Replacement Hangar 9 10cc Valiant fuselage – Click Here

Source for aluminum tubing – Click Here

Have a comment on this How-To story? –Email Me!

Back to the How-To list – Click Here