Elastic Launched Glider C

rmp509
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Re: Elastic Launched Glider C

Postby rmp509 » January 22nd, 2014, 9:40 am

can someone tell me how changing the angle of the horizontal stabilizer in the rear of the glider would affect the flight?
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Re: Elastic Launched Glider C

Postby fanjiatian » January 22nd, 2014, 11:32 am

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag

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Re: Elastic Launched Glider C

Postby rmp509 » January 22nd, 2014, 11:52 am

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag
im sorry what i meant is changing the angle of the entire stabilizer in aspect to the fuselage as in making the stabilizer join at an angle with the fuselage. one example is like adding some balsa shim under the rear of the stabilzer which makes the rear of the stabilizer higher than the front or vice versa if adding the shim under the front of the stabilizer
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Re: Elastic Launched Glider C

Postby AtRi » January 22nd, 2014, 12:01 pm

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag
im sorry what i meant is changing the angle of the entire stabilizer in aspect to the fuselage as in making the stabilizer join at an angle with the fuselage. one example is like adding some balsa shim under the rear of the stabilzer which makes the rear of the stabilizer higher than the front or vice versa if adding the shim under the front of the stabilizer
The changes you suggest will function just as the elevator would on an aircraft. If the leading edge of the stabilizer is higher than the trailing edge the plane's nose will be pushed downwards. Likewise, if the leading edge is lower than the trailing edge then the plane's nose will be pushed upwards.

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Re: Elastic Launched Glider C

Postby rmp509 » January 22nd, 2014, 12:12 pm

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag
im sorry what i meant is changing the angle of the entire stabilizer in aspect to the fuselage as in making the stabilizer join at an angle with the fuselage. one example is like adding some balsa shim under the rear of the stabilzer which makes the rear of the stabilizer higher than the front or vice versa if adding the shim under the front of the stabilizer
The changes you suggest will function just as the elevator would on an aircraft. If the leading edge of the stabilizer is higher than the trailing edge the plane's nose will be pushed downwards. Likewise, if the leading edge is lower than the trailing edge then the plane's nose will be pushed upwards.
Thank you!!
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Re: Elastic Launched Glider C

Postby jander14indoor » January 22nd, 2014, 2:18 pm

And of course it is more complicated than that. What AtRi said:
The changes you suggest will function just as the elevator would on an aircraft. If the leading edge of the stabilizer is higher than the trailing edge the plane's nose will be pushed downwards. Likewise, if the leading edge is lower than the trailing edge then the plane's nose will be pushed upwards.
Is correct as far as it goes, but isn't the whole story for these gliders due to the wide range of speeds these things fly over.

For good transition (which is CRITICAL to good times) you want to have the wing and elevator on parallel planes.
Instead of rudder changes, you should use center of gravity changes more to control nose up or down attitude.
Using elevator to bring the nose up will increase looping tendencies on launch and make transition more abrupt, losing altitude instead of smooth transition to glide.

Regards,

Jeff Anderson
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Re: Elastic Launched Glider C

Postby fanjiatian » January 23rd, 2014, 4:29 pm

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag
im sorry what i meant is changing the angle of the entire stabilizer in aspect to the fuselage as in making the stabilizer join at an angle with the fuselage. one example is like adding some balsa shim under the rear of the stabilzer which makes the rear of the stabilizer higher than the front or vice versa if adding the shim under the front of the stabilizer
Ah, that'd give you positive and negative incidence respectively. You want to keep the incidence at 0-0 (what Mr. Anderson mentioned) so that your glider doesn't loop or do a nose dive at the transition.

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Re: Elastic Launched Glider C

Postby AtRi » January 23rd, 2014, 7:11 pm

Looking at the glider from the rear, raising the right edge of the horizontal stabilizer would make the glider turn right and raising the left edge would make the glider turn left
If you want to change the rudder, gluing the front edge of the rudder to the left side of the fuselage and gluing the back edge of the rudder to the right side of the fuselage (so it points northwest) makes the glider turn right. Reverse it if you want to turn left.

Changing the rudder affects the turn at higher speeds but creates more drag. Changing the horizontal stabilizer creates less drag
im sorry what i meant is changing the angle of the entire stabilizer in aspect to the fuselage as in making the stabilizer join at an angle with the fuselage. one example is like adding some balsa shim under the rear of the stabilzer which makes the rear of the stabilizer higher than the front or vice versa if adding the shim under the front of the stabilizer
Ah, that'd give you positive and negative incidence respectively. You want to keep the incidence at 0-0 (what Mr. Anderson mentioned) so that your glider doesn't loop or do a nose dive at the transition.
While I do stand corrected in that adding/subtracting ballast should be the primary change when balancing the glider, I disagree that the glider should always be at 0-0 incidence. I always add a little bit of negative incidence to my gliders and I have had great success. I find it to be more of a balancing act between adding/removing ballast and adding/removing incidence, rather than strictly one or the other.

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Re: Elastic Launched Glider C

Postby jander14indoor » January 24th, 2014, 1:48 pm

I won't argue with experience about the exact right setting of stab to wing. But I think we are agreeing that you set the stab primarily to control transition (and that it will be near 0-0) and cg to control glide pitch.

And a truism about planes is that seldom (never?) can you change one control factor without impacting the correct setting of another. Frankly, its that messy interaction of the control inputs which makes gliders/airplanes such interesting devices to teach proper test and evaluation procedures.

Of course the fact that its fun when they fly right doesn't hurt any.

Jeff Anderson
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Re: Elastic Launched Glider C

Postby fanjiatian » January 28th, 2014, 5:08 pm

While I do stand corrected in that adding/subtracting ballast should be the primary change when balancing the glider, I disagree that the glider should always be at 0-0 incidence. I always add a little bit of negative incidence to my gliders and I have had great success. I find it to be more of a balancing act between adding/removing ballast and adding/removing incidence, rather than strictly one or the other.
Interesting! It's really cool how filght characteristics are so different for each glider and design. Negative incidence usually causes my glider to do a hard crash at the transition. I actually build a bit of positive incidence before trimming to avoid breaking my glider on the first flight
Adding ballast definitely has an enormous impact on the glider


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