If calculation results in CG=30%MAC, you need to locate that spot on the MAC, then project that spot to the fuse. Please note that MAC is somewhere outboard on the wing/stab. Try to locate your CG as close as you can to the calculated value. Choose the static margin you want (I typically choose 15%) and let this program calculate the ideal CG for the airframe. Wing AC or stab AC, by convention, are located at 25% MAC of each surface. Tail moment is distance between wing AC and stab AC. Go to this site, and plug in your model's fundamental areas, moments etc. Here is a link to the trimming method I used.It works well. I may experiment with adding more positive incidence and take out the down thrust to see where that gets me. Down lines still required 2% down elevator mix, but the up-lines cleaned up after doing that. One other change I made was I added a little down thrust using one washer which helped the pull to the canopy on up\down lines. I just followed the Triangulation Trimming Method as close as possible. Any recommended incidence is just a base reference for you. The airplane will let you know what it wants and that's how I went about it. I initially set up my incidence with a borrowed H9 meter but I could never get a consistent reading with it so I gave up and just went flying. That gave me pause! Again, I think I will leave it at the 0.5-0.6 for now based on your post (without Gators, tweaking CG is dicey as stock) which is a good thing since my H9 incidence meter just died! I will soon have to replace it, any recommendations? Thx! Could some of this ''where should my batteries be'' back and forth on the threads be due to variations in batches or even individual examples? Anyway, the choice of wing incidence is my next question with a post above about pushing towards 0.8 - 1deg. After all, it is balsa and ply and those materials must be very difficult to keep constant at this price point. The idea of batch variation, at minimum from last year's fin/rudder design to this year's new config, grows stronger in my mind. Also, I have been thinking that this design has a very wide CG range which makes it forgiving to those of us who are relative new to pattern (this is my second season and first 2m ship) and your observation above supports that thought. Your reported flight experience increases my confidence that the config is in fact, very close. Was thinking maybe I should move the packs back again towards the 181 end of my range but now after reading your post above, I am not going to make any changes unless we observe some new flight charateristic that needs to be addressed. That said, last night I put mine back up on the balance to re-check CG (still at 186 after a minor repair undid some recent weight reductions LOL) AND have a cold hard look at the elevators as trimmed: they were nearly neutral, just a hair of up, less than 1mm. There were at least 2 other Vanquishes at Pocono pattern last weekend with batteries more forward than mine and I have read about many others out there on these threads with packs more forward than mine. Other than that, no other bad tendency anywhere else flying the Advanced schedule. I do have a slight pull to the right on exit when pushing to inverted for the full roll outside loop and I have not found a satisfactory fix for it yet. I am at about 200 or so flights with it this way. The plane fly's well in advanced for me with this setup. I installed gator adjusters on the front which made incidence adjustments much easier, It was well worth the time to install them. I made adjustments to my incidence until my up trim went away and to set the aileron trim. I am using a Himax 210 and a heavy APC prop so take that into consideration with your setups. I just kept moving my packs back until pitch coupling went away on knife edge. In my experience, the Vanquish is not real cg sensitive as I have moved my packs around without much trim change. I have my cg set at 190 which puts my packs about 1inch or so in front of the wing tube.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |