ORIGINAL: fthumma
Bill & Dan,
How can using 10 oz of fuel make this such a drastically different plane? It goes from being a blast to fly to being a big handfull flying like its tail heavy[for me] in just a few minutes. The cowl made a big difference, too. Those 2 clicks of up came out and add 2 down. I brought it in pretty hard the last time. Left wheel marks on the bottom of the wing. The gear and mount seem fine. I think I jinxed myself putting the cowl on. I'll have it off now to check it over really well. I think the battery is going to make a trip forward, at least for a day.
Fred,
The main difference is the tank is well forward of the CG point.
It's been a while and I do not remember the weight of glow fuel per ounce but 10 ounces that far forward is going to make a difference. That's why I suggested the CG I mentioned in my emials to you. It sounds as though even with the cowl on you were tail heavy, very tail heavy at the end of your flights
Here is what I would suggest, start with the CG 1/2 inch forward of the recommended spot and have the cowl on. Take off, get it trimmed out with the TX and then pull a 45 degree upline, once you have the line established, roll the plane over, make sure it is stillon that line and then let go of the elevator, you want to the plane to come level, inverted, in around 3 to 5 seconds. Now fly around for about 5 minutes and do the same thing, this time it will probably take around 5 to 7 seconds to come level. Doing it this way indicates just how nose or tail heavy you are. If the nose drops, the time it takes to come level is a good indication of how heavy you are. If the nose stays on the line, you are neutral, if the nose climbs tyou are tail heavy. This is the main way we do it in IMAC to get the CG the way we want it
I would be glad to meet up with you anytime in the evening during the week and most anytime on Saturdays to get this solved for you. I'll email you my phone number. I am available every day this week after 4:00pm and this Saturday.