Flying Wing Vertical Tip Sizing Help

[CloudyIFR]

Well I guess the subject says it all, but I'm looking for a formula on how to deteremine winglet size for a flying wing. At this point I'm not interested in airfoil, wash in/out just the area of the tiplet.

Thanks
Curtis
Montana

[JetPlaneFlyer]

Find a proven model of similar type and overall layout to the one you are designing and make the fins about the same area in proportion to the models overall size.

Not very 'scientific' I know but very effective ;)

Steve

[macboffin]

Make a little chuck glider to scale, say 10 inch span, from thin sheet, try with fairly large fins, keep trimming until it gets unstable.(Allow for smaller fins being lighter, reduce nose ballast slightly at each cutting.

[BMatthews]

Actually if they are TOO big it'll be spirally unstable. If too small then you get bad yaw damping. But with the short coupling of a flying wing it's pretty hard to make them too big.

Part of the size required will depend on the amount of sweep. The required size being related to how far to the rear of the side view neutral point of areas you are. It's often termed as being the vertical tail volume coeficient.

[Ralph Walton]

If the wing is well designed and trimmed , it will fly just fine with no tips. At low speeds it will be "squirrely" and at certain flight angles just about invisible.

Don't get too hung up on them. Try making them out of something simple and cheap like coroplast or plastic sheet. Just tape them on with fiberglass reinforced tape and experiment with different shapes by cutting them with scissors at the field.

I usually go for as small as I can see comfortably.