[img]i/expressions/face-icon-small-frown.gif[/img] Happened to be browsing and found your question about Kress Fans. I have one of the 40 size fan units. I was not impessed with it. I put it in a Zeroli F-4 Phantom. I could never get it off the ground. It made a great car but that wasn't what I was looking for. Where the main bolts attached to the engine I got severe cracking and had to reinforce these areas with glass cloth. I was using a K&B 7.5 with a K&B pipe. On 35% nitro I did manage to get around 22,000 RPM's so I should have had enough thrust to fly the model. It wouldn't even move on grass so I took it to the local airport and tried it, no luck there either. Some day I may try an original design with more wing area. The unit looks great and maybe in a differant application it might work.