Before I deployed in May of 2023, I did a lot of R/C airplane repair work for a friend. As payment for that work, he gave me a previously crashed Hangar 9 Beast 100cc, which is a biplane that I’ve wanted for quite a while. Those who listen to the podcast know that I love biplanes! I didn’t have a chance to really give the airframe a good inspection before I left, so I had 6 months to think about it while I was gone (and I thought about it almost every day, lol). When I got home, I had a few other small projects to work on and one very large one (long story, but suffice it to say that I had to buy a “beater with a heater” for basic transportation due to my primary vehicle going down for the count). After those issues were handled, it was time to bring the big Beast home. Once it was in my basement workshop, a thorough inspection revealed more problems than I had previously estimated. The aircraft appears to have been crashed at least twice, as the landing gear area already had an old (very bad as it turns out) repair with multiple covering patches covering some not-so-pretty balsa repairs underneath. The story that my friend got with the airplane (he received it in a package deal buyout situation) is that the previous owner was hovering at the time of the crash. The engine (DLE 111 V1) stalled in the hover and the aircraft flopped on it’s back and impacted the runway bottom-side-up, destroying the internal cabane strut mounting locations, the center wing panel, and all four wing strut attach points out on the wing panels themselves. With a new clear view of the damage, and a little encouragement from my friends, I’ve decided to attempt to repair the airplane and get it back in the air. Follow along as I try to make a flyable airplane out of one that likely should have been relegated to the dumpster, lol!
Here she is. This is what I had to work with after removing all the ‘stuff’. Have a look at that firewall, lol! The DLE 111 was mounted to that flat piece of plywood due to the motor box being damaged/removed from previous ‘repair’. The plywood was attached to the airframe with…drywall screws. Yeah, drywall screws. The good news: that ugly piece of plywood was firmly attached to the fuselage sides and inner structure. I tried to remove it to facilitate building a new motor box and mount. It wouldn’t budge. So, I reinforced it in the areas I could reach and prettied it up a bit. More on that later…
Here are the wings and center wing panel. What you can’t see in the picture below (more on that when I get to the wings) are the broken center panel mounting points, and all four broken wing strut mounting tabs. Once I start working on them, I’ll go over how I repair them. And there is the ‘stuff’ I removed from the airplane so I could work on it. A DLE 111, landing gear, wheel pants (not in this picture), pipes, fuel tank with nasty old smelly gas, a carbon spinner and prop (minus about an inch off one blade, lol) and various other bits and pieces. Disregard anything that isn’t a Beast in the picture!
I figured I would start with the fuselage since I would need a complete fuselage to repair the wings. As I received it, there was no way to attach to top wing as every point of attachment was either gone or damaged. I began by getting the center cabane mounts fixed. This turned out to be a little more difficult than I anticipated. The fuselage structure by design is very lightweight with only enough material to complete the airframe as a solid unit. It’s amazing how brittle and fragile the structure becomes as you remove pieces of it. The engineering that goes into the design of these modern aerobatic planes is impressive, with every piece only as strong as it needs to be once joined with the other parts. These airplanes are definitely built to fly, not withstand crashes!
Below: One of the new mounts being test-fitted in the old location. In the foreground you can see other broken/missing wood in the cabane mounting area. Note the hole in the sheeting with the light shining through where the cabane will eventually exit the fuselage and support the center wing panel. I had to replace quite a bit of sheeting in this area on both sides.
Working inside the fuselage was a pain, and since I had to repair some of the sheeting around the cabane struts anyway, I decided to remove the sheeting so I’d have better access to the inner structure. Off comes the covering… The covering came off in two large sections. If you look at the picture, it appears that the forward piece of covering was not factory applied, lol. This area looked to me like it was from a previous repair.
I began by removing as little sheeting as necessary as I wanted to save as much of the original structure as possible, especially if it was still sound. Here you can see my replacement cabane mount trial-fit in place on the LH side. You can just make out the RH side if you zoom in, lol. The LH side fared a little better than the RH side in the crash, although it required removing a little more sheeting than the RH side.
Here’s the RH side. I didn’t have to remove as much sheeting here, although more stuff was broken on this side. You can see a piece I added to bridge the gap on the broken framework. Not pretty, but functional, lol.
With the cabane mounts repaired, I repaired the sheeting. As per the original, I used two layers of 1/16″ sheeting for my repair pieces.
It also needed a little sheeting repair from where the cowl had been pushed back into the top of the fuselage.
Had to get a picture with the cabanes mounted and the yet-to-be-repaired center wing panel sitting in position. I love biplanes!
With the cabane mounts and sheeting completed, I turned my attention to the gear block area. That chunk of wood with the four holes in it is not supposed to be laying loose in the pipe tunnel, lol. I epoxied the block back in it’s original location, then tried to brace the area wherever I could. There is not a lot of meat in this area, so hopefully the reinforcement I added in this area will be enough to keep the gear from getting ripped out when I inevitably make a not-so-perfect landing. Ideally, I would have incorporated the aluminum angle mounting bracket hardware into my doublers. However, there was no access to the bolts to remove them, so fingers crossed that this is enough.
More sheeting repair around the area where the gear got ripped out previously. The previous repair here didn’t address the sheeting and just left holes where it was missing.
Next up was the firewall. What a mess. Since the plywood was firmly attached to the fuselage (I tried very HARD to remove it, and it wouldn’t move without causing more damage to the airframe). I decided to keep it. I cut a pair of 1/4″ plywood doublers to fit on the front and back of the ply firewall to attach the engine to, instead of simply bolting it (along with a lot of spacers) to that ugly firewall. I did this for two reasons: 1) to make it prettier and 2) To seal up the firewall and try to keep exhaust residue out of the fuselage. I also added tri-stock to the inside where the firewall meets the fuselage and on the outside in an attempt to further seal it up. With that huge hole in the middle of the firewall, a lot of exhaust oil made it all the way back to the radio mounting area. Gross.
Test fitting the cowl revealed a little mistake I made by not thinking ahead. I had to remove some of the tri-stock I installed previously to clear the plywood cowl ring. No biggie.
Starting to look like I might pull this off!
Now to re-mount the engine. Since the ply firewall was glued to the fuselage at 0/0, I had to add a few degrees of right thrust as per the original. I decided I would do this with shims under the mounting flange on the engine. I just had to figure out how far to off-set the mounting holes to get the spinner centered in the cowl. Here’s the method I used. Worked like a charm. I shifted the mounting holes just over 1/2″ to allow for the offset and it worked out great.
Yes, I will be ordering a new prop, lol. It’s worth mentioning that of the original considerations for this project, budget wasn’t one of them. In light of recent events (car trouble), it has become necessary to limit discretionary spending, lol. Up to this point, I have exactly $0 in this project. I will eventually need to order a prop, four servos (at least, since I have not tested the servos that are still installed in the airframe for the elevators and rudder), probably a roll or two of Ultracote, a receiver, a couple LiFe batteries, and maybe a few other items. But I am hopeful that the engine is ok as I haven’t ran it yet. I did measure the runout on the crank and it appears to be straight, so that’s a good sign. If the engine proves to be a dud, it is likely that this project will sit for quite a while, lol. I’m not sure what, if anything, I’ll do about those two gaping, ugly holes in the cowl bottom previously used for the factory DLE mufflers. Since I’ll be running cannisters on this one (because that’s what it had when I got it), it would be nice to seal up these holes and paint it. But that’s two processes I hate doing: fiberglass work and paint, lol! So we’ll see. The whole cowl could use a repaint honestly.
I couldn’t resist putting everything together to get a glimpse of what it will look like when completed. Airplanes are cool! Cooper approves.
After enjoying the views of the assembled fuselage, it was time to take it all apart and ‘pretty up’ the firewall area and get it ready for repairing the covering to try and make it look good again.
Here’s the firewall with a little paint on it to hide some of the ugliness…
With the fuselage pretty much done minus a few areas requiring filler and final sanding, it was time to move to the center wing panel. The center wing panel was in pretty rough shape. Three of the four wing mount tabs were broken, with two of them still in the wing panels themselves. When the airplane impacted the ground, it broke the cabane/wing mount plates and shoved two of them through the top of the panel. So, I carefully removed the covering (in case I need patterns or pieces of the gold for the eventual re-cover) to assess the damage and plan a repair. In the photos below you can see the “exit wounds” the mounting plates made when they left the chat. I removed the entire upper covering in one piece! If it weren’t for the torn area, I’d try to iron it back on after the repair, lol!
It was interesting to see the structure beneath once the sheeting was removed. I don’t know what kind of glue they used at the factory, but it wasn’t anything I’ve see before. Looked kind of like Elmers school glue, lol. Not the prettiest construction with gaps in the joints here and there.
Below, you can see the one undamaged remaining cabane/wing panel mount. Although, upon close inspection you can see that the tri stock and ply rib that the plate is mounted to is cracked. It was still solid, so I saturated the tri-stock with thin CA and went over the rest of the joints with med CA, just to be sure. You can also see that the plate was never fully seated into the rib from the factory, although it did protrude to the other side of the rib, as designed.
I cut three new plates for the mounts and glued them into the existing holes with epoxy. I copied the existing design and incorporated tabs on the plate to key into the ribs, as per the original. One of the end ribs was damaged when one of the plates broke away from the structure, so I had to make a little filler so I’d have something to mount the sheeting to. With all the mounting plates repaired/replaced, I drilled the cabane mounting holes for the blind nuts and replaced the sheeting. I’ll use the wing panels to locate and drill the wing mounting blind nuts once the center section is complete.
In order to give the sheeting something to “sit” on, I glued strips of balsa to the underside of the old sheeting where there would have been no support for it otherwise. Adding the sheeting was pretty straightforward. After it was sheeted, I added filler and sanded smooth, then added filler again and sanded again for a smooth finish. Once the center section was sheeted, I added the access holes for the cabane struts to mount to the center section.
With the holes opened up for the cabanes, only one thing left to do… Yay, it fits!
Here’s a view of how the cabanes pass through the sheeting and attach to the mounting lugs. I had to enlarge the holes for the cabanes a bit. Better to not remove enough than too much!
Definitely getting there. I’m pretty happy with how the center panel came out. Initially I thought I would have to build a completely new panel. Glad I could salvage this one.
With the center wing panel pretty much closing out the fuselage repairs, minus some final sanding and covering, it was time to move on to the wings. All four were damaged to some degree, with the top right panel taking the most damage. I’ll just detail the repair of that panel, since the other panels were basically similar repairs minus a few steps. The damage wasn’t visible until I opened up the panel. I tried to do all the repairs from the underside of each panel, so I could hide the covering patch on the bottom of the wings. With the exception of the bottom left panel, I was able to do it that way. Similar to the fuselage, I began by removing the covering in the damaged area so I could get at the structure. Removing covering, especially on open structure (not sheeted), should be done strategically. I knew I would need areas to adhere the replacement covering patch to, and it needed to be enough for the covering to stick to without pulling away from when shrinking. That’s why the repair area appears larger than it needed to be. I wanted to be sure I could patch the covering and get it tight. In addition, I didn’t know how much structure I would need to remove to get the repair done. As it turns out, I didn’t need to remove much more than just the plywood rib. In the photos below I’ve removed all the damaged/splintered lit-ply. I had to get creative with the exacto to remove the ply ahead of the spar. Basically I snapped off a dull #11 tip so the the end was about 1/8″ wide, and used that to chisel out the damaged rib. I used scrap pieces of balsa to begin making a templates for the aircraft ply repair parts. Using my balsa templates, I cut repair pieces out of 7-ply aircraft plywood. 1/8″ in this case.
Next was to create a doubler to tie everything together. I’m using 5-ply 1/16″ for the doubler. With the parts cut and sanded for fit, it was time to glue everything up. I used 30 minute epoxy to give me time to get everything aligned. How about those custom clamps, eh? The last two photos show the holes for the blind nuts that receive the screws from the struts, and the balsa cap strips I added so the covering has something to grab on to when the times comes to re-cover. And finally a little black paint to make them match the covering, as per the original. I repeated this process, more or less, on the other wing panels.
As I was cleaning up the area I was working in, I couldn’t help but look at the fuselage and think about that ugly firewall area. So, I set out to clean it up and add some strength at the same time. I added some framing with 1/4″spruce stick. I joined some cross-grain balsa 3/32″ and sheeted this area. The area aft of the gear mount will have to remain ‘uncovered’, as this will need to be accessed for the lower wing bolts. As I was working in this area of the fuselage I noticed that the front lower sheeting was incredibly thin and not ’round’ like the profile should be. So I added some 3/32″ balsa sheet to the area to stiffen it up, and also to sand to a rounded profile as it should be. It will also provide a nice solid surface to stick the covering to when the time comes. I test fit the engine/exhaust to make sure I had clearance around the pipes. I had to tweak the headers a bit so the pipes wouldn’t rub the landing gear block. Looking at the pipes, it appeared they were rubbing this area previously. Looks like I have the clearance needed now.
I went ahead and straightened up the exhaust tips while I was at it, lol! Once I was happy with the fit, I added the sheeting with the cutout for the tips. I think it looks pretty clean. I decided to add a removable panel toward the front so I could access the pipe clamps for future servicing. Since the pipes were kinda grimy, I went ahead and polished them up a bit. I think it looks pretty good, definitely better than it was, and hopefully stronger now too. Now that it’s all sanded and ready for covering, I’ll touch up a few of the painted areas and make it look presentable. Even though I’ll probably be the only one that sees it, I’ll feel better about it at least.
I made a trip to my favorite hobby shop, Dynamic Balsa in Leonore, IL. and found just enough Ultracote True Red to patch up the project. With covering in hand, I decided to start the recovering process with the fuselage. After a light sanding, I used a tack cloth to remove any remaining ‘stuff’ that might prevent the covering from sticking. As you can see below, I used the original covering that was removed as a template for the new pieces.
This is where the new name will go, once I decide on one, lol!
I had to recover half of the top of the horizontal stab. The existing covering had been re-shrunk before using too much heat, and all the seams had pulled away from the joint with the fuselage.
Next up was the upper wing center section. I used the wing panels to make marks on the section for reference, so I would be sure to get the trim to line up.
With that done, a quick couple covering patches to the wing panels and covering was done!
Not too bad in my opinion. At this point, the repair/recover process is pretty much complete.
Yours truly with his newly recovered airframe!
Re-installing the Fuel tank/engine/exhaust/radio/etc. was pretty straightforward, similar to building an ARF. I wanted to be sure I didn’t add any unwanted incidence to the wings with my repairs, so I double checked them with an incidence meter. With the tail level I was pleased that all four wing panels and center section were within 1 degree of the tail. Considering the amount of repair to the top section, I was pretty happy with that. I can fine-tune after the re-maiden if necessary with shims under the center section mounts and out at the interplane struts.
Looks like I may need to go with a smaller prop for ground clearance. I’m using a 28 x 10, which is the recommended prop for the DLE 111. I might try to grab a 27 x 10 or 27 x 12 for additional clearance.
After a carb rebuild, the DLE 111 seems to run ok. I posted the run video on our RCPlaneLab Facebook page. Enjoy! I’ll get better pictures of her out in the sun on re-maiden day and post them here. But, for now, this completes the build/repair log. Hope you’ve enjoyed it!