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Annoying trainer habit
How do I keep my Hobbistar from increasing altitude when I throttle up? I know this is a trait of trainer style planes, but it's annoying. I'm going to try increasing my down thrust a degree or two but wanted to know if there was something else I could try. Maybe I have to live with it...
Thanks Scott |
RE: Annoying trainer habit
try raising the back of the wing about a 1/4" Just use a couple of popsicle sticks. That way you can adjust it till you like the results.
Dennis |
RE: Annoying trainer habit
Okay. I am confused. I am relatively new to the hobby, but I thought all planes would increase in altitude when you increase the throttle setting. You are going faster at a higher throttle setting and you are, therefore, increasing airspeed. Wouldn't you increase lift at a higher airspeed all other things being equal?[sm=confused.gif]
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RE: Annoying trainer habit
Another option is to adjust the aileron linkages to "reflex" the ailerons up a bit. Use small adjustments (a couple turns on the clevis at a time), and adjust them equally. This effectively reduces the incidence angle of the wing, and will reduce some of the nose up tendencies with throttle. You can also increase the down thrust of the engine by adding washers behind the engine mount.
Brad |
RE: Annoying trainer habit
Use down elevator trim.
Gibbs |
RE: Annoying trainer habit
Michael:
Your right. (Almost) all planes will do this to some degree, but the trainer setup is most prone to doing so. |
RE: Annoying trainer habit
All the other sugestions are good. Another thing you can do is move the CG back a little bit. Try moving it back about 1/8 inch and see if you can tell any difference. Don't go too far back or you will need another airplane.[&o]
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RE: Annoying trainer habit
An airplane that is balanced correctly will climb with throttle if you have positive wing incidence or a high lift wing like a trainer. If the wing incidence is correctly set, probably 0 degrees for your trainer, then you can counteract the extra lift with some engine down thrust. Most trainers have some engine down thrust set in the firewall. You can add more by putting a couple of washers behind the top motor mount bolts between the firewall and mount. The popsicle sticks under the trailing edge is a good idea, but you will lose lift at slower speeds making takeoff and landings more difficult. If you do have positive wing incidence, then the popsicle sticks are the correct solution.
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RE: Annoying trainer habit
Because I am old, I remember that you trim the airplane for glide and adjust the engine thrust for powered flight. Of course, that thrust adjustment will only really work perfectly for one specific throttle setting.
It is a trainer!! Learn how to trim for each throttle setting you are using. When you are ready to cease with the balancing act of re-trimming for throttle changes and fighting "ZOOM", get yourself a "nuetral" airplane. (Zero incidences and fully symetrical wing). Have a ball!!! Ken Erickson, AMA 19352 |
RE: Annoying trainer habit
If you have a computer radio some have an option that allows you to program in elevator trim to match throttle setting for this exact reason.
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RE: Annoying trainer habit
It is normal for all aircraft to climb when power is added. Set your throttle to the speed you are going to fly, then trim the aircraft for straight and level flight. As you increase throttle the aircraft will tend to gain altitude, as you decrease throttle the aircraft will tend to lose altitude.
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RE: Annoying trainer habit
As many others have said above, this is completely normal. Don't try to adjust the angle of the wing or to make any other mechanical adjustments to compensate for this. If you think about what is actually happening you will understand why you don't want to make mechanical adjustments on the plane. Ok, let's look at the plane. Let's say it's flying along at half throttle and you have the trim set for level flight. The speed of the air flowing over the wing is producing enough lift to keep the plane from falling, but not enough lift to climb. Now as you increase the speed of the plane the air will flow over the wing at a faster rate, thus producing more lift so the plane now climbs. It's nothing more than simple aerodynamics at work here. As others have said, trim the plane for the speed you want to fly at.
Hope this helps Ken |
RE: Annoying trainer habit
Sounds like you may be ready for plane with a semi symmetrical wing
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RE: Annoying trainer habit
I would go with the down elevater trim
__________________________ SoneDeaf |
RE: Annoying trainer habit
Most ARF's have a pre-set amount of down-thrust built into the firewall. This works for only a given thrust and speed range. If you are flying faster than the speed this is desiged to counteract, you will climb. More downthrust will give you an almost linear correction. More speed = More downward thrust.
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RE: Annoying trainer habit
ORIGINAL: RCKen As many others have said above, this is completely normal. Don't try to adjust the angle of the wing or to make any other mechanical adjustments to compensate for this. If you think about what is actually happening you will understand why you don't want to make mechanical adjustments on the plane. Ok, let's look at the plane. Let's say it's flying along at half throttle and you have the trim set for level flight. The speed of the air flowing over the wing is producing enough lift to keep the plane from falling, but not enough lift to climb. Now as you increase the speed of the plane the air will flow over the wing at a faster rate, thus producing more lift so the plane now climbs. It's nothing more than simple aerodynamics at work here. As others have said, trim the plane for the speed you want to fly at. Hope this helps Ken |
RE: Annoying trainer habit
ORIGINAL: M. Michael Meyer Okay. I am confused. I am relatively new to the hobby, but I thought all planes would increase in altitude when you increase the throttle setting. You are going faster at a higher throttle setting and you are, therefore, increasing airspeed. Wouldn't you increase lift at a higher airspeed all other things being equal?[sm=confused.gif] Some models climb with speed. Some are set to fly level at full throttle and sink at lower power. (Just the opposite). The full symmetrical wing also tends to have a wide envelope. As airspeed increases the tail lifts and the effect is to lower the incedence of the wing into the relative wind. Once it achieves level flight further throttle just makes it go faster, not upper. |
RE: Annoying trainer habit
Hi!
All high winged trainers need engine down thrust to counteract trimchanges due to different throttle settings.If you trim your airplane out this way you hardly notice any deviations at all from flying straight at all throttle settings. It's my opinion having flown R/C planes for 31 years that all models should be trimmed out at full power. |
RE: Annoying trainer habit
Umm just a though depending on your tx could you not maybe mix some down elevator to the trotal so that as you add power you puch the plane doown counter actuing the more lift that is generated.....
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RE: Annoying trainer habit
Lots of different views on this one.
If you want to correct this issue the two things to try are down thrust and wing incidence which have been mentioned earlier. They are both very easy to do and if approached in reasonable increments there is little chance of a bad outcome. I would try adding downthrust first by putting a washer under the back engine mounting screws, if you used self tapping screws or the engine mount is the clamping type then I would put the washers between the engine mount and the firewall at the top. When I was trying to fix my trainer adding downthrust did not get the job done, it just made it much more difficult to takeoff and land. Leaving the downthrust at factory setting and putting two popcicle sticks under the back of the wing did the trick for me. I found the plane to be much more enjoyable to fly once it was closer to neutral. |
RE: Annoying trainer habit
ORIGINAL: Flying freak Umm just a though depending on your tx could you not maybe mix some down elevator to the trotal so that as you add power you puch the plane doown counter actuing the more lift that is generated..... Ken |
RE: Annoying trainer habit
i see good point Ken sorry...
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RE: Annoying trainer habit
Thanks for all the input! I'll try some of the things suggested such as the trailing edge and trim adjustment. I guess what it really comes down to is I'm expecting a trainer to do things it's not designed for. I do have a four star, so I can probably live with my trainer flying like a trainer...
Scott |
RE: Annoying trainer habit
You did not mention what type of trainer it is. I started with the Hobbico Nexstar Select which had some difficulties right off the bat due to it being a RTF. First off both the areilons were too tight on the servo causing a flap type situation which made it climb under heavy throttle. The airplane also came with speed flaps which gave alot of lift. After adjusting and removing the planes speedflaps I got it to go straight and fast. Just a quick story of what happened to me:D
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RE: Annoying trainer habit
I'll repeat what I wrote earlier. Set the power to what you are going to fly at and then trim the aircraft for straight and level. This is the proper way to fly any airplane, whether it is full scale or rc aircraft size. The fundamental aerodynamics are the same for full scale or model. Learn to fly the plane properly and it will serve you well in the future when you go to more advanced aircraft and flying. Power controls altitude and nose position controls speed, this is the basic premise of all powered flight.
Regards, doubledee |
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