Preface: I often have a tough time differentiating between home and work...I do stuff at home the same way I do it at work...Some may consider this overkill (It May Be for these Toy Airplanes??)
ORIGINAL: flywilly
The rational for using the largest patch first is to get maximum contact around the damaged area to reinforce the fiberglass, then fill up the hole. I was told this years ago by a boat builder. Of course we don't need to be waterproof, but those holes can make some pretty interesting whistling noises...at speed
-Will
I suppose that's OK for boats...But it ain't how you fix Airplanes...
Using the largest patch first in effect reduces the strength of the repair to only one ply...The rest turn into "body fillers" and have reduced or no structural value...
As for a structural repair on an Aircraft component...All efforts are made to match the original density of material and then also matched in ply orientation from a stress/loads standpoint...All repairs are scarfed or stepped per ply with a minimum of 1/2" overlap (or per engineering)...It is accepted that a secondary bonded repair will not be as strong as the original laminate...Which makes it more critical that the repair be done in such a fashion to maintain the original integrity...You start with a small patch and grow in size on the way out...
Again...A secondary bonded repair will never be as strong as the original laminate...But if done correctly you can gain a large percentage of the original strength back...Workmanship and attention to detail are key elements in a successful bonded repair...
ORIGINAL: WEDJ
If a crack is not too bad, a doubler from inside attached with CA will strengthen the area, then CA on the outside, be sure to sand as soon as the CA sets up. It gets harder as a few hours go by.
There is a right way...And there is a "Not so right way" as I mentioned in another thread...
I imagine allot of folks would take an approach like this with these toy airplanes...I'm sure there are hundreds of repairs flying around out there which have used this method or similar...They may last forever??
I know this ain't the Space Shuttle!! I'm pretty much an arse who thinks somebody's butt will be in the seat...