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incidence question and problem
I have assembled and I'm currently flying an arf. It wants to climb at 1/2 throttle and higher. When I adjust the down trim in the elevator to get it fly level and I'm comin in to land I pretty much run out of up elevator to flare...It's an esm stuka. The stabs are glued in with dowels for setting the tail incidence. Im positive it isnt a balance issue.. Am I correct in assuming I cant check the tail incidence since the elevators are glued in? And about the only thing I can do is to put some washers behind the top of the engine to add some down thrust and point the front of the engine down? Thanks for the help in advance.........
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RE: incidence question and problem
I would try try downthrust. May work.
Builder may have put the firewall in a tad crooked. Tom |
RE: incidence question and problem
Thats what I was thinking too....Thanks.......
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RE: incidence question and problem
Did you do a engine up/down thrust test?
What type of plane is it? What is the dwon thrust angle at now? |
RE: incidence question and problem
Andrew,
Since you mentioned angle of incidence this may be a good place to mention that you may want to look at the decalage. In your case, decalage is the differences in angle of incidence between your wing and horizontal stab. It is also the differences in top and bottom wings for biplanes. This may sound like nit picking, but it is a major point with some models. Just a personal opinion, but I avoid down thrust on engines until all else fails. You are compensating one problem with another set of problems. Is there any way for you to shim the trailing edge of the wing? I've done that with soft pads, and sometimes with ply glued in place. If I need to shim I always take various thicknesses out to the field to experiment. The plane will probably track and groove better if you get the decalage set better. |
RE: incidence question and problem
<span style="color: #ff0000">Hello Andrew, Some comments in red trying to help you..</span> ORIGINAL: Andrew_S I have assembled and I'm currently flying an arf. It wants to climb at 1/2 throttle and higher. <span style="color: #ff0000">The rate of climb and descent of an airplane is controlled by the power setting. If you have a powerful engine set at half throttle it may still produce too much power to maintain level flight. </span>When I adjust the down trim in the elevator to get it fly level and I'm comin in to land I pretty much run out of up elevator to flare...It's an esm stuka. <span style="color: #ff0000">You may have a decalageerror (see decalage explanaion in the other postings) upon assembly. To nose down and reduce the angle of attck of the main wings and thus reduce lift, the elevator has to go down and lift the tail. That would provide more up elevator available.</span> The stabs are glued in with dowels for setting the tail incidence. <span style="color: #ff0000">A tail incidence is a measurement of angle to a reference line. It does not change the fact that in level flight at cruise speed the stab and elevator should be in the same flat geometrical plane (zero deflection) and have zero angle of attack to the flight trajectory. The main wing incedence is then set to produce a lift equal to the weight at the cruising speed. </span>Im positive it isnt a balance issue.. <span style="color: #ff0000">Do not be so sure that the balance is correct. </span>Am I correct in assuming I cant check the tail incidence since the elevators are glued in? <span style="color: #ff0000">The tail incidence is measured between the stabilizer and the reference line. It will affect only the fuselage attitude in flight. The fuselage attitude is not that important. An attitude 2 or 3 degrees off will hardly be noticeable when looking at the aairplane while flying. I have to guess that when you write</span><span style="color: #339966">"since the elevators are glued in"</span> <span style="color: #ff0000">is an honest mistake. Elevators have to move to control the airplane pitch attitude. </span>And about the only thing I can do is to put some washers behind the top of the engine to add some down thrust and point the front of the engine down? <span style="color: #ff0000">Try to avoid down thrust (as another fellow has mentioned). Consider that in level flight the elevator should be in line with the stabilizer (no deflection), that tail should have zero angle of attack and th main wing incidence should be such to produce the lift equal to the seight at the cruising speed.(part throttle).</span> Thanks for the help in advance......... <span style="color: #ff0000">Hope this helps. Do some studies on aerodynamics of airplanes.</span> Best regards de Zor |
RE: incidence question and problem
Thanks for the help....It's an esm stuka arf. I was meaning the elevator hinges are glued in...So I should try to shim the wing first by putting in some washers at the back of the wing ?
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RE: incidence question and problem
ORIGINAL: blw Andrew, Since you mentioned angle of incidence this may be a good place to mention that you may want to look at the decalage. In your case, decalage is the differences in angle of incidence between your wing and horizontal stab. It is also the differences in top and bottom wings for biplanes. This may sound like nit picking, but it is a major point with some models. Just a personal opinion, but I avoid down thrust on engines until all else fails. You are compensating one problem with another set of problems. Is there any way for you to shim the trailing edge of the wing? I've done that with soft pads, and sometimes with ply glued in place. If I need to shim I always take various thicknesses out to the field to experiment. The plane will probably track and groove better if you get the decalage set better. |
RE: incidence question and problem
I cant get the meter on the wing because of the flaps and ailerons. It got the L shaped hinges on those surfaces that wont allow the meter to attach, unless I trim a lot of the plastic mount off..The fuse is fiberglass, but I will try adding some shims to the rear fist and see what happens....Thanks for the help...
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RE: incidence question and problem
If you shim the back of a low wing A/C it will cause it to climb even more with power. You would have to shim the front, which may not be possible with that plane.
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RE: incidence question and problem
Andrew S , I would suggest you revise thebalance (CG location). Adding weight to the back as one suggested will move the CG toward the tail will be opposite to what you are trying to accomplish. If you do not have a specified CG location, I would set it to be between 28% and 32% of the wing chord at the fuselage measuring from the leading edge of the wings. Adjustments could be done later by observing the flight behavior while flying. Best regards de Zor </p> |
RE: incidence question and problem
Follow this chart:
http://nsrca.us/all/flying/177-trimchart.html If everything else fails, try reflexing the ailerons a little. |
RE: incidence question and problem
Thats what I was thinking it would do, climb even more... Well i guess I will just turn the ailerons and flaps upward some more or just fly it by holding down elevator all the time..[X(]
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RE: incidence question and problem
Andrew,
Just balance your model. That is all you have to do. Perhaps seek the help of someone at the flying field. It is ridiculous to fly with constant down elevators. Zor |
RE: incidence question and problem
ORIGINAL: cfircav8r If you shim the back of a low wing A/C it will cause it to climb even more with power. You would have to shim the front, which may not be possible with that plane. |
RE: incidence question and problem
ORIGINAL: Zor Andrew, Just balance your model. That is all you have to do. Perhaps seek the help of someone at the flying field. It is ridiculous to fly with constant down elevators. Zor |
RE: incidence question and problem
Gray Beard,
You no doub realize why I wrote the second line in my previous posting. quote "Perhaps seek the help of someone at the flying field." unquote. Regards and take care Gray. Zor |
RE: incidence question and problem
ORIGINAL: Zor Gray Beard, You no doub realize why I wrote the second line in my previous posting. quote ''Perhaps seek the help of someone at the flying field.'' unquote. Regards and take care Gray. Zor |
RE: incidence question and problem
Thanks guys, I really appreciate the help .... Now on the other hand, no matter where you look on here, there is always some dumb smart arse who feels the need to be just that..A DUMB SMART ARSE! ! Just what the hell does the quoted post below have to do with anything to do with this thread or any other thread on this forum? I dont recall asking anything about peeing.. Yes the question was asked at the field so your "drift" was wrong. And by the way, I got it figured out..Turned out it wasn't the incidence...It wasn't the balance....It wasn't anything that was talked about from the nice folks who tried to help...I would post on here what the problem was, but you or some other smart arse jerk would probably have some other dumb and ignorant comment to post...And before I forget, it shouldn't be "there" pants, it should be "their" pants!
Have a wonderful day...... [quote][/Gray Beard Date 9/8/2010 12:34 PM You can pull down there pants but you can't pee for someone. quote] |
RE: incidence question and problem
[quote]ORIGINAL: Andrew_S Thanks guys, I really appreciate the help .... Now on the other hand, no matter where you look on here, there is always some dumb smart arse who feels the need to be just that..A DUMB SMART ARSE! ! Just what the hell does the quoted post below have to do with anything to do with this thread or any other thread on this forum? I dont recall asking anything about peeing.. Yes the question was asked at the field so your "drift" was wrong. And by the way, I got it figured out..<span style="color: #ff0000">Turned out it wasn't the incidence...It wasn't the balance....</span>It wasn't anything that was talked about from the nice folks who tried to help...I would post on here what the problem was, but you or some other smart arse jerk would probably have some other dumb and ignorant comment to post...And before I forget, it shouldn't be "there" pants, it should be "their" pants! Have a wonderful day...... [/Gray Beard Date 9/8/2010 12:34 PM You can pull down there pants but you can't pee for someone. quote] i can esily understand why you wrote <span style="color: #ff0000">"Turned out it wasn't the incidence...It wasn't the balance....".</span> Then proceed to give yourself a reason for not stating what you and your friends found. We sure knew what is (was) the problem you have (had). Not confirming it doesnot change anything. I did the best I could to help you and wish you all the best cooperation your recent posting can bring you in the future. You did not have to lock your door. It appears that you may need lots of help in the future. Good luck. Zor |
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