The 27” Desser tires are for 8” wheels. This is not the only time I have heard the 26” ultralight tires are prone to damage. I think it depends greatly on how heavy your plane is. If you have a 4-500 pound light plane you’d probably be okay. More than that, I would say go with the Airstreaks. If you have one of the fat-assed late model 900 pound planes, the “standard” heavy carcass tire would be better.
Those are definitely undercambered wing ribs. You can see the extended mounts for the flapperons and the undercambered shape clearly. These are not model IV wings. The doors are flat bottomed so it’s not a 1. This is is either a 2 or 3 model depending on the lift struts.
I have an opportunity every year of being involve at the AirVenture UL area. I’ve seen many of these alternative engines in person. I see which ones fly and which ones do not. The last Hog-Air powered plane I saw there was a Pietenpal. These fly reasonably well with a 40 hp model T or a 75 hp Corvair engine. With the HD engine it was barely operable on the field. The next year the plane came back with a Corvair.
It was first flown a couple of times a year ago then abandoned. I’d bet because it is seriously underpowered. It was flown, found to be a complete dog, now being dumped for a fraction of what a good flying plane would get. I dont buy the comment that after building this plane he all of a sudden decided he needed a twin.
Ive seen this now a couple of times. Where is this coming from because it is not true. Rotax still makes the 582 and fully supports it. They stopped 503 production several years ago, parts can be a challenge, but can be found.
This quote from the website tells you everything you need to know on this engine. It is a race engine. It is designed for maximum performance output, not longevity. Definitely not something that I would fly behind even if the company would sell you one.
I'd be willing to bet you have an alignment issue. The larger, softer, smooth tires are allowing more slippage which masks the problem. The photo with the 21x800/6 tires on the plane even looks like it has quite a bit of tow out. With the geometry of that gear, as it moves through it's travel it will make it worse.