DualDesertEagle
I'd just like a little check up on this by some aerodynamics experts:

On my AL-609 C Dominator Prototype I wanna do some testing with and without the wing strakes being doubled up by a KF-2 airfoil.

Is my assumption correct that WITH the wing strakes beefed up there's more drag and the center of lift is shifted slightly forward, allowing the plane to be flown a tad more nose heavy?

Coz if this happens to be the case I'd like to add this info to my easy-build plans so ppl can choose between 2 slightly different behaviours.
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DualDesertEagle
Really, no one?
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e3_Scott
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I'd just like a little check up on this by some aerodynamics experts:

On my AL-609 C Dominator Prototype I wanna do some testing with and without the wing strakes being doubled up by a KF-2 airfoil.

Is my assumption correct that WITH the wing strakes beefed up there's more drag and the center of lift is shifted slightly forward, allowing the plane to be flown a tad more nose heavy?

Coz if this happens to be the case I'd like to add this info to my easy-build plans so ppl can choose between 2 slightly different behaviours.


Extending your KF2 forward to cover your strakes/LERX is not going to affect your center of lift or your CG much in my experience, not that you have to start shifting a bunch of weight forward to balance the plane anyway nor will it make your plane fly naturally nose heavy. It will make the airflow smoother over the entire wing/strakes, perhaps making your plane feel a little smoother and stable over not having KF extending over the top of the strakes.

If you are designing this plane to fly KF2 only, it might make it a bit "floaty" which may make it feel/fly a bit tail heavy or cause the nose to want to float up needing more weight forward to keep it balanced in flight. What percentage of chord length are you using for your KF airfoil sizing? For most swept wing planes, starting at about 40% of chord is a good benchmark. Make it much more than that and you start to really affect the relationship between the CG and CL. Behaviors that can indicate this is the plane can have a regular tendency to fight itself in turns where the nose will want to rise or drop and not track true. Also, if you are in a dive, it can take a lot more effort and altitude to pull the nose back to level as the plane will not rotate as easily in the pitch axis if the KF is too big in relation to the wing chord.

Good luck

Cheers,

Scott
Park Jet noise...the "other" sound of freedom😎
#ParkJetnoise #ParkJetpilot
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bogusbandit56
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I'd just like a little check up on this by some aerodynamics experts:

On my AL-609 C Dominator Prototype I wanna do some testing with and without the wing strakes being doubled up by a KF-2 airfoil.

Is my assumption correct that WITH the wing strakes beefed up there's more drag and the center of lift is shifted slightly forward, allowing the plane to be flown a tad more nose heavy?

Coz if this happens to be the case I'd like to add this info to my easy-build plans so ppl can choose between 2 slightly different behaviours.

I don`t think KF`s on the lerx will make a marked difference.
Wot, no Depron?
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DualDesertEagle
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Extending your KF2 forward to cover your strakes/LERX is not going to affect your center of lift or your CG much in my experience, not that you have to start shifting a bunch of weight forward to balance the plane anyway nor will it make your plane fly naturally nose heavy. It will make the airflow smoother over the entire wing/strakes, perhaps making your plane feel a little smoother and stable over not having KF extending over the top of the strakes.

If you are designing this plane to fly KF2 only, it might make it a bit "floaty" which may make it feel/fly a bit tail heavy or cause the nose to want to float up needing more weight forward to keep it balanced in flight. What percentage of chord length are you using for your KF airfoil sizing? For most swept wing planes, starting at about 40% of chord is a good benchmark. Make it much more than that and you start to really affect the relationship between the CG and CL. Behaviors that can indicate this is the plane can have a regular tendency to fight itself in turns where the nose will want to rise or drop and not track true. Also, if you are in a dive, it can take a lot more effort and altitude to pull the nose back to level as the plane will not rotate as easily in the pitch axis if the KF is too big in relation to the wing chord.

Good luck

Cheers,

Scott


Ok, I guess I'll leave the strakes un-KF'd then and make sure I've got no more than 40% covered like I did on my self-designed BF-109.
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e3_Scott
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Ok, I guess I'll leave the strakes un-KF'd then and make sure I've got no more than 40% covered like I did on my self-designed BF-109.


Based on my testing and experience, the plane will actually fly a little bit smoother with the KF extended forward over the strakes/LERX like I mentioned in my first response. I tested this theory on the F18 V3 and found the plane did feel smoother and slightly more stable with the KF extended forward. I didn't use the area of the LERX to calculate the 40%. When calculating the 40%, I made a line straight along the leading edge of the wing up to the fuselage, measured along the fuselage to the trailing edge of the wing, used that to calculate the 40% and then just measured the wing tip chord and took 40% of that, then drew the KF from there.

Your design, your choice, good luck

Cheers,

Scott
Park Jet noise...the "other" sound of freedom😎
#ParkJetnoise #ParkJetpilot
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