RE: DA Engine & DP Edge
Hi I noticed a few posts about the YS 140DZ. On a plane like the Edge in question I wouldn't run one. They are perfectly good engines for a pattern airplane, but they are VERY expensive to operate. The fuel has to be a special DZ blend which happens to be expensive 30% nitro with special oil content. They suck that fuel down like crazy too. It'll be a 28 dollar day everytime you take a plane out to the field with one of those things on the nose. The reward however is SERIOUS power! That engine has ALOT of power! I see no problem at all with a DA 50 on that plane. I suspect (and it's hard to say without actually seeing it do it) that the plane exibited what is commonly called 'sympathetic vibration' or what the techies call 3rd order harmonics. It's something that happens when the 'tune' of an 'impulse' equals the 'tune' of the airplane. It can be tricky to solve sometimes as it must be solved thru a process of elimination and isolating possible causes. This is not the fault of a component or the total number of componets even. It is a rare occurance that happens when conditions are 'just right' with the components. The reason I think that this is what's hapening is becasue the frequency of the wing occilations and the fact that the poster said 'he was afraid the plane was gonna break up'. That is VERY severe and does happen with flutter but not usually at lower airspeeds and power settings. The 3rd Order Harmonics happens at certain power settings when the conditions are just right, and he said it ceased the instant he reduced power which leads me to beleive that power setting is somehow related. This is something that you may want to check for with some guys that have been in this for a real long time. It is something that definitely can be disastrous, and that's why I thought I would bring it up. Maybe this will help you solve the issue. I really hated to see it caused damage.