How To Make A Structural Repair On Fiberglass Wing Leading Edge

With the 2022 Calibration Main's Championships just a few weeks away now, here's a trivial glimpse into the journey in getting there. In addition to this, I besides had some pains at the Gilman Springs qualifier besides which I wrote nigh in my coverage from the issue. And then, it's been an interesting year that ultimately has improved the airplane as a whole, but non without a lot of frustration and multiple stints of repair work through the year. Just, with a little persistence (and lots of complaining), I remember we've got it all worked out and the Delusion IIIRS is ready to become big at Woodland-Davis!

It has been said there are two types of model airplanes… those that have crashed and those that Volition crash…

Well, if you follow this site on Instagram or Facebook then you know that the inevitable happened! My competition Mirage IIIRS crashed! I was at an event back in October last yr and for whatever reason, the fan wasn't making the power information technology typically does during takeoff. The takeoff gyre was sluggish and instead of aborting and taking dwelling a perfectly fine plane, I forced the airplane off the ground thinking it would exist ok once airborne. Unfortunately, that wasn't the case and I couldn't get enough distance to get the speed upwardly and the plane concluded up landing in a few large bushes. I walked upward to the airplane expecting the worst and found it upside downward but thankfully by and large in tact. I was very fortunate! The most damaged surface area was the nose section being broken merely thankfully still continued to the airplane. I later discovered that the lack of thrust was likely due to a combination of tired batteries non belongings voltage under load and a fractional blockage in the exhaust duct existence acquired by some loose tape that I was unaware of. Thankfully it was repairable and so I thought it would be a adept opportunity to discuss some bones fiberglass repair. Oh, and the lesson here??

LESSON OF THE Twenty-four hours: If your airplane isn't doing what you expect it to, arrest and troubleshoot!

Olfactory organ REPAIR

The nigh impacted area from the crash was the nose. Though technically notwithstanding attached to the fuselage, information technology was pretty "crunchy" and loose. Both sides of the olfactory organ were cracked just frontwards of the inlets below the canopy. The right side took most of the damage which is the side I'm guessing impacted the ground showtime (the canard was also cracked on this side also). Likewise, the whole front camera screen and pitot tube were gone from the very front end and nowhere to exist establish.

The kickoff thing to exercise was to re-set the nose to get it back in place. This was washed simply by piecing the $.25 back together on either side and using thin and medium CA to glue information technology all back. This was just to hold it in place and so that a more structural glass repair could be washed. With it all tacked back together, some 2 oz cloth was cutting and placed on the inside of the broken expanse through the canopy hatch surface area. Note that I clamped a couple hardwood rails to the nose to ensure that the nose remained straight during this process. From there, I used a laminating epoxy to wet out the fabric while it was in place in the fuselage. Since I had it bachelor, I used the resin system that my folks apply for their fuselage layups (non a readily available resin). A adept and easily accessible option is West Systems 105 with 205 or 206 hardener. I know a number of folks who use this resin with splendid results. The nice affair with the West Systems is that in that location are different hardeners bachelor that allow for a faster or slower cure time depending on what you need. Now, to employ the resin, I used a inexpensive disposable paint brush (at 50 cents, nosotros spared no expense!) to wet out the glass cloth while the cloth saturday in identify over the surface area needing repair inside the fuselage. In applying the resin, less is more as you don't want to apply too much. It should be applied as necessary simply to wet out the textile…remember, more resin = more weight! The cloth should change color but non be overly glossy (glossy areas are typically resin pooling). To soak upwardly any backlog resin, I simply applied some toilet paper to the wet material, tapped it with the resin brush and peeled it abroad. From there, nosotros let it cure and come back to start the outside make clean up work!

To practise the cosmetic repairs, I used USC Icing which is a lightweight finishing putty to fill all of the affected areas from the crash. A sanding block was used to sand the contours and smooth information technology all out once the filler was cured. I usually have an assortment of different sized sanding blocks with different grit sand papers to do this work. In that location'due south no i size fits all, merely usually I resort to well-nigh a half-dozen″ to a 12″ sanding block. A few passes were required to go the contours smoothed out and cleaned up. Once I was happy with that, then I locally primered all of the effected areas with Evercoat Automotive Primer.

mirage-fiberglass-14 To fix the tip of the nose where the beveled photographic camera window and pitot tube are at the front, I had to become a little creative. I had to build back up the material as there were pieces missing that we weren't able to locate in the crash. To do this, I glued some 1/xvi″ balsa wood on the within of the nose where the nose pieces were missing. From there, I added Icing filler over those areas (the forest served as a shelf for the filler). The filler was contoured with a sanding block to match the olfactory organ shape. The last particular of business organisation was to replace the brass tube pitot receiver on the acme of the nose. This was done the same as was done originally. The area where the pitot receiver tube was to get was opened upwardly using a dremel. From there a brass tube was epoxied into place which acts equally the pitot tube receiver (an aluminum pitot tube slides into the contumely tube when on the aeroplane). Lastly, Icing was practical and sanded to cease out the contours around the pitot receiver and the rest of the nose. Since the nose front is a camera window, I closed it all up with a clear plastic confront and masked off the camera window contour in prep for primer and paint touchup.

Fly REPAIR

The fly repairs were pretty uncomplicated. The leading edges were all chewed upwardly forth with a couple of the pylons. To repair the wing leading edges, I showtime hardened upward the exposed balsa wood with some thin CA (necessary so the Icing filler will stick to it). From there, I just filled all of the affected areas with Icing Filler and sanded it all to match the wing leading edge contours again. From there a couple light coats of primer were applied focalized in those areas and it was prepare to touchup the paint.

PAINT TOUCHUP

Matching the paint tin can be difficult in these repairs. Since I built and painted the aeroplane, I have plenty of paint to spare! If you're repairing an ARF or something someone else built, then it's probably all-time to accept pigment matched and mixed. Even having the pigment on manus, the colors do tend to change tones slightly from sun exposure and whatnot (using a non-yellowing articulate coat is disquisitional to avoid a good portion of this!). So, to blend it all, I decided to repaint the unabridged nose. As well, localized areas effectually the inlets and the wing leading edges I sprayed using a wider spray pattern to effectively create more of a 'blend' on the paints. Thankfully, the shades all matched upwardly very well and any tonal differences really but wait like touched upwardly panels and areas that y'all would get on the full sized airplane. The most hard to blend was the underside lite color based on the weathering that had been done. So, using some artistic washes, I composite the underside colors equally much as possible. Though not perfect, it'southward certainly good plenty as the full size is never perfect either! Note that sometimes it'south meliorate to touch on upwardly the paint by masking off areas. Since I was dealing with larger areas and solid colors, I opted to go with the wider spray to help information technology all blend.

mirage-fiberglass-27 Once all of the pigment was touched up, information technology was a matter of re-applying the panel lines and raised panels onto the airplane that were missing as a result of the repairs. For panel lines, I re-practical them the same every bit initially made. I plotted them out with a pencil and then use a double concluded scribe with rulers and circle templates, I scribed the panel lines into the paint. Raised panels were washed using cut vinyl. For raised panels, I like to pigment them separately from the model as this gives a slight color variation which accentuates the paneled look which adds to the realism. Once all of that was done, the weathering was re-practical to assistance dirty up the freshly painted areas. To do this, I like to brush Raw Umber acrylic artists paint onto the surface over the details and so wipe it off with a paper towel soaked with some Tamiya Acrylic thinner. Equally it is wiped off, the pigment remains in the console-line recesses and effectually the raised panels. How dirty the end is simply a role of how heavily the paint is wiped off. My MO here is less is more usually. I do plan to cover this specifically in a split up article in the time to come.

With everything all touched up once more (including reapplication of some dry out transfers) and finalized I finished it all off past re-applying a articulate glaze over the entire airplane. Instead of localizing the clear to just the repaired areas, I applied information technology to the whole aircraft to aid blend it all back together which it did. It gave the airplane again a prissy uniform cease like information technology had before the crash. Note that I don't utilise a heavy articulate glaze, information technology's mostly but a dusting since it's really just practical to even out the paint finish and protect the weathering work that's been done. For clear, I apply a non-yellowing lacquer satin.

FAN TROUBLESHOOTING

Troubleshooting the fan was a must. There's no reason to set the airplane if we don't empathise what happened! The E-Turbax fan and Neu motor had been bullet proof for many years and so understanding what went wrong was paramount. Upon pulling the fan from the plane, the showtime affair I noticed was that there was some record hanging inside the duct. You encounter, for ESC cooling, I like to tape the ESCs to the top of the exhaust ducts exposed in the airflow every bit this helps keep them extremely cool during performance. I typically tape on the outside, only at one indicate I had placed a piece of tape on the inside of the duct across the ESC. Well, unknown to me, information technology was now hanging well into the exhaust period. At offset glance, I wasn't too concerned. I ran the system on the bench which showed decent numbers. However, while running the fan in an instant the tape started fluttering inside the duct and I saw over a i lb subtract in thrust and the tone of the fan changed radically. In remembering what occurred when it crashed, the fan didn't sound correct on the roll out which must have been the tape fluttering. Very interesting! Also, the batteries were one-time and seemed to be struggling. So the verdict was that the combination of the tape fluttering in the duct with the tired batteries not putting out the power they should have caused enough of a performance decrease to make the airplane power marginal. Ultimately, there was nothing wrong with the fan or motor which is skillful!

Since I had the fan out of the airplane, I idea it would be worth installing and trying a JetFan 120 in the airframe. The motor used was a Neu 1917/1Y (590Kv) which based on the specs would give about 16 lb thrust at nigh xc amps using 12 lipo cells. In demote testing these numbers proved to be about correct. With the same tired batteries from the crash, I was seeing about fifteen.5 lb thrust at about 85 amps. This was good enough for me, so the fan was installed into the aeroplane and has since proven to be an crawly power organization for the mirage. With the lower current draw, the flight times have significantly increased which is ideal for contest and the overall functioning is really slightly better…what actually seals the deal is the sound! It'due south the most turbine sounding EDF installation I've heard! Notation that the bore of the fan is slightly less than the East-Turbax which the inlets were designed for, and then I CAD modeled an adapter ( available through my 3D Printed Products Folio ) that I then 3D printed on my Robo3D. Also, the recommended frazzle for the fan is iv″. Based on the afterburner lights I have in the airframe, I was limited to 3.75″ exhaust diameter which has proven to be fine thus far. In ground testing, I didn't see whatever difference in current draw running the fan without the frazzle or with the 3.75″ exhaust which told me that the it wasn't struggling to much.

Here's a quick flight video to give an idea of the JetFan 120 (note the sound!)

For comparison, here's a vid with the original power system.

Adjacent time nosotros'll talk about building detail parts such equally pitot tubes and antennas every bit I lost a few in the crash and thus had to re-build them. Until next fourth dimension, I'll see you at the field!

The RC Geek Blog is your place to acquire almost all aspects of the RC hobby. Learn to build, pattern, bulldoze or fly that RC project you lot've e'er wanted to build, simply take been intimidated to try. This blog is here to help yous on your journey and provide tips and tricks as you go! My hope is to inspire builders both experienced and new! And so, welcome, please look around, it's an heady beginning! I'g currently documenting my latest competition scale RC jet build, a Mark Frankel F4D Skyray, along with some other fun tips and videos. If you can't find what you're looking for on this front page, click on whatsoever of the categories to the right and it volition show simply posts related to those categories. Please experience free to add together comments and/orcontact me directly if you take questions, I'chiliad here to assist! And don't forget to check out myYouTube Channel, I postal service new videos every calendar week!