RE: Sig Astro Hog @ 150% ?
At one point years ago someone made a giant scale kit of the hog. I can't recall who but it was big.
The Saito twin is a very cool engine but for even a .90 they were under powered. Most of the ones I have seen used were in Cubs and they lend themselves very well to that plane.
Enlarging plans is nothing new. We used to project them onto a wall with big sheets of paper tacked up and just trace them. Then some of the copy services started getting in bigger copy machines that could do it a lot better.
The only trick to it is as the plans are enlarged so is the size of the wood so it's up to the builder to figure out what size wood should be used. Just because the wood is enlarged from 1/8 to 1/4 doesn't mean you need to use 1/4, it can still be 1/8 or 5/32.
It just requires some thinking on the builders part. I still do it today by making templates of the parts in a kit then going to Kinko's. The charge by the sq. in. and it isn't cheap. I just had a copy of one page of plans for a little 1/2A plane and the cost was $10.00.
Do the research first like going to Kinko's and see how big they can enlarge to.
It's easy and fun.
Also start thinking about a good gas engine for a plane that size. When I get to about 80 inches I go to 40cc. Depending on the weight of the plane you are thinking about you may decide on something bigger like a G-62 or one of the new gassers from China.
Don't forget about the servos you will now require. Big controls on a heavy plane require some good servos.
See the money adding up!!
I gave up building planes over 80 inches for several reasons, money was at the top of my list but there are others.