|
|
United States, NV, Las Vegas
Joined Jan 2010
10 Posts
|
Discussion
pattern plane set up question
I’m building a GIFFIN 2M composite pattern plane with hacker C-50 motor that I recently purchased from F3A unlimited and I have a question in regards to the set up.......Are pattern planes usually set up with 0 degrees down thrust and 0 degrees incident for the wing and tail? There doesn't seem be any instructions available and F3A is not answering my request for set up info
|
|
|
|
|
SUBBED
|
|
|
|
pattern is something that I am getting into myself and over the last few years I have had a lot of exposure to it and so far I have found that everyone sets up the incidence differently. You should be perfectly fine by using 0, 0 as your starting point and then you can dial it in from there, that is the nice thing about all the adjusters that pattern airplanes have. With a lot of the pilots I know they will leave the wing at 0 and tend to adjust the tail based on visual ques like how the airplane looks when flying horizontally and also how much trim they are carrying.
I also did a quick seach on RCU and found the following post by Chris Moon of F3A Unlimited Setting up the Griffin like our demo plane will give you a good solid flying plane. These are the settings where we have been flying this plane for over 100 demo flights and it works really well. Set the spinner to match the nose and use those thrust settings. Set the C/G to the front half of the wing tube (this is slightly nose heavy but you can move back to fit taste). Set a meter on the canopy rails, you will see there is a raised area that helps align the canopy and take a reading. Now put the meter on the wing and set the wing 4 1/2 degrees positive to the canopy rail. This is NOT the same as 4 1/2 degrees of positive incidence, it is 4 1/2 degrees up RELATIVE to the canopy rail. Now put the meter on the stabilizer and set it 3 1/3 degrees positive to the canopy rail. This is where we are flying the demo plane and it flys great there. Here is the thread http://www.rcuniverse.com/forum/m_11..._4/key_/tm.htm |
|
||
United States, VA, Aylett
Joined Feb 2006
763 Posts
|
Quote:
I know the guy who helped Chris set-up the F3A demo Griffin and has put a ton of flights on it. I'll try to get you in touch with him. And, as Kevin mentioned, check the thread in the rcu pattern forum. There is a very active pattern contingent over there, lots of good resources and info. t |
|
|
||
Joined Jan 2006
1,835 Posts
|
Quote:
You will need some difference in incidence between the wing and stab and the thrustline will end up where it is, generally you will match what's molded in, but it could require adjustment particularly when you change propellers. Generally you want to set the wing such that the fuselage will fly at a "good" attitude and looks good rolling. Set the stab to remove the trim. What you end up with is basically a bit of positive incidence in the wing, even if it is zero relative to the reference line of the fuselage. I would anticipate that with an airplane like the Griffin, you will end up with about 1/2-3/4° difference between the wing and the stab (with the stab being NEGATIVE incidence relative to the wing). You may be around 1-1.5° downthrust relative to the wing and 2° right thrust is generally a good starting number. Wing adjusts the flying angle of the fuselage. Stab basically "gives" you AOA. Regarding CG, I generally set up my pattern planes so that when, from upright, you pull to a 45° upline and roll the airplane inverted, it will fly straight for a bit and then start to gradually drop off. I hope this helps! |
|
|
|
|
Almost all pattern planes are set up with little positive incidence, around .5 degree. Stab is set to 0 or whatever it takes to make the plane fly level with neutral elevators. Every airplane with a fully symmetrical airfoil needs to have the wing slightly positive otherwise it couldn't fly. If you set an airplane up 0-0 you will be flying with the whole thing at slightly positive attitude with up trim. This can translate to all sorts of other trim issues so it is much better to just set the wing slightly positive.
|
|
|
Ocoee, Florida
Joined Jun 2009
192 Posts
|
I set my pattern planes up to fly around 25% MAC.. This usually result in about .5-1deg positive on the wing but thats relative to the zero line which you may not know. From my experience setting the plane up at this MAC results in excellent tracking and snaps and solid control feel with minimal expo as well as eliminating a great deal (if not all) of the coupling usually associated with rearward CG's. My current plane only requires a downline mix (elevator-throttle) other than that it has zero mixes. Coupling and the associated mixes can create unwanted tendancies that can result in large coarse deviations, increase pilot workload and make the whole thing more complex than it has to be. The only negative I have found using the "forward CG" approach is that the plane will require more push for level, inverted flight but this can be easily corrected with no or negative expo at the beginning of down elevator.
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |