This series of e-mails and comments documents the incredible repair job that Alex Hall performed on my damaged Spread Tow Supra center panel. First some background, the aircraft involved with this repair is my 2011 Spread Tow Supra. It has a carbon spread tow centerpanel and weighed-in at 57.3 on it�s maiden flight.
She experienced some minor fuselage damage at the MASS contest in April in Pittsburgh which I repaired in rather cave-man style. Then, at the DBSF contest in July of this year (2013) I experienced a mid-air collision with an Aspire (I think it was an Aspire, not sure). At the time of the mid-air I was thermalling at about 1,200 ft ~0.4 miles to the north out over the river approximately at about 5 minutes into a 10-minute flight. All of a sudden the dot that was my plane stopped moving when another dot came in to the picture. It took a few seconds to regain control, and hear the collision, but I was able to regain control and complete the flight.
Upon landing the post-flight inspection indicated that the damage was pretty significant. Evidently the spread tow skin is very strong and light, but does not hold up well in a mid air collision. The damage to my Supra was much more significant than to the other plane, which flew the next day. There was a gash in the left leading edge of the centerpanel about 2/3rds of the way out that extended back to the spar. In addition, there were delaminations in the top and bottom skins behind the spar in the area of the impact. The left aileron was pushed up a little in the area of the linkage. The aileron linkage was kinked. There was also some damage to the tip panel skin near the root of the leading edge top and bottom.
Alex Hall came up to me and volunteered his assistance. With the F3J Team Selection only ~month away I eagerly accepted the help, especially since I had seen some his miraculous repairs and knew he would do a great job. Here are the e-mails that Alex sent to me to keep me informed of his progress. They are posted here to allow others to learn and benefit from Alex�s techniques.
First e-mail on 7/18/2013:
Just a quick update for your reassurance!
The cores for the leading edge, both top and bottom are completed. They're well bound to the kevlar and fair enough for the next step which is the layer of carbon, which will tie in to the existing spread tow skin.
The delaminated ripple on the the top skin, behind the spar, has come out really well. I'm very happy with it as it's very fair and strong. The next big project will be the delam on the bottom skin, behind the spar. This will be harder to repair as it's compressed beneath the level of the spar. So what I'll be doing is making a long key for the length of the damage and inserting it from the joiner end. I'll rotate this key to raise the skin to its correct height and then make the delam repair just like I did for the top skin.
If the weather remains too hot to crack on at work on the schooner, I should have the structural repairs completed by the weekend, then will begin the even longer process of cosmetics. I have no concerns about the structural repairs done and as long as the spar hasn't been compromised in areas I couldn't see, you should be back in business! The current weight of the wing is at 617g so that's about 1/4oz increase.
So yes in effect I'm rebuilding the leading edge from the inside out.
Cheers,
Al
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Second e-mail on 7/20/2013:
Hi Josh,
Thanks for the compliments but necessity was my driving force through most of life!
Here are a couple more shots. The leading edges are finished, they just need some fine fairing, all the top surface and lower leading edge are ready for final fairing and paint. Next task will be the delam on the bottom.
Weight to date, 622g or 21.87 oz, so thats an increase of 12g or about 1/2 oz .
Cheers,
Al
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Third e-mail on 7/22/2013:
Good morning Josh,
Wing is all done, all that's left is paint. But before I get carried away , I'm just going to primer it up and get it to you to fly at Horsefeathers.
That way if the spar was compromised it will fail before fiddly hours are spent in finish work!
I won�t be attending Horsefeathers, but both David Beach and Walter Adazick are, so I'll try to get the wing to them this week and they'll in turn bring it down with them for the weekend.
The AUW is now at 634g which is 22.3oz, so thats an increase of 0.917 ounces. I couldn't do it any lighter I'm afraid. The bottom delam was the most consuming of material and added weight.
Launch it hard and lets see what breaks. If it doesn't fail in Virginia, give it back to David or Wally and I'll finish up the cosmetics. Oh, when you refit it to the fuse check the flap subtrim as I had to remove the pushrod/linkage on the side that was damaged.
Cheers,
Al
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Fourth e-mail n 7/23/2013:
Good morning Josh,
Wing AUW, gear installed, primed, ready for final sanding and gloss is in at 636 grams, an ounce on the dot.
I'm heading up to Nashua, NH, tomorrow and handing it over to David Beach, who'll bring it down with him to Virginia. If it doesn't break, give it back to him and he'll give it to me on the way back to NH, for gloss work. If you're doing the CRRC event I'll have it with me then, if not we'll make other arrangements.
Cheers and hope it works well.
Al
Fifth e-mail on 9/23/1013:
Hi Josh,
Just a couple of quick photos of the top ready for final polishing. Its a good match.
Cheers,
Al
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Post-repair notes: The Spread Tow Supra flys great! Don't know if it is possible, but it seems like it is better than before the mid-air, but that could be due to some increased practice. The results are impressive with this repaired aircraft winning the last 4 ESL contest days I flew in. Amazing and many thanks goes to Alex!
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Spread Tow Supra repair
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Posted - 10/07/2013 : 12:32:50 PM
