29erJuliet

I just finished outlining a Burnelli Inspired twin.

I am kit bashing a Sig Senior for the frame, mostly because...the one I've had for over 10 years is a great flyer and am planning to use the wing ribs for the Burnelli.

Question is: Burnelli used tapered wings on his latest few creations...the earlier UB-20 sported a the hershey bar type wing...the cb 16 slightly tapered at the ailerons. Everything else that I am aware of had tapered wings.

So...in a smaller model...what's the better wing to use?

The wing span will probably be as long if not a little longer than the original senior.

Thanks

29erJ

BMatthews

The basic hersey bar wing will help avoid tip stalling. Also it's far easier to make. But they often don't look as "finished". But a nicely shaped wingtip can often do a nice job of hiding the simple look.

Rotaryphile

A 40-percent tapered wing will produce about 12% less induced drag, and over 3% less profile drag than a constand chord wing of the same aspect ratio. It also generates less aileron yaw, and is structurally lighter. Note spelling: "chord", not "cord". If the structural complication of taper is not attractive, a well-rounded wingtip, where planform curve at the trailing edge extends inward about one chord, produces at least 6% less induced drag than a wing with square tips.

cyclops2

What do you want the plane / wing to be better at when finished ?

29erJuliet

Cyclops...if I understand your question correctly...I want the wing to produce better lift.

Rotaryphile, thanks for correcting my spelling...and the info.

29erJ

cyclops2

If you can weigh up the total major parts of the plane or use a accurate estimate. You can then decide if the Burnelli wing will keep you at you comfortable wing loading.
If you should come up with a acceptable wingloading using ONLY the rectangular portion of the wing, the tapered part is just going along for a ride and looks.
That would be ideal. Could you still cut extra constant chord ribs to get the " comfortable " wing loading ?

BMatthews

29er' there's a very good reason we don't see a big use of Burnelli style wings for aircraft today. It's because the idea didn't work anywhere near as well as the inventor hoped. By all means go for doing it but don't expect the "lifting fuselage" to contribute as much lift as the area of it suggests compared to a thin and narrow fuselage and regular wing.

The reason it doesn't work that well is due to the massive vorticies that will form off the "tips" of the fuselage. Yes there will be some lift. Much in the same manner as we see with model style "flying saucer" disk shaped wings and the pizza box flyer square wings. But it's not the best use of the lifting area and there's higher drag than normal at slower speeds as a result.

Mind you our needs don't match those of commercial aviation so you may end up with a model where the oddball traits it has makes it more fun or useable to fly.

29erJuliet

There are a couple Burnelli models flying. One on this site...Ed Moorman, I think...both commented on the great ground effect they had.

As far as drag...look at the Israeli F-15 that flew and landed with one wing. The fuse...and plenty of thrust kept is aloft.

I've read alot about Burnelli designs being draggy. Also though...the slab sides of the fuse act like a fence, seperating the airflow over and under the fuse.

Could be a bunch of fun.

29erJuliet

Cyclops,

I was thinking about that for the constant chord wing. I never thought about it for the tapered wing, that could be a possibility. On a few of his wings the tips get pretty narrow.

hmmmm

cyclops2

If you build the inner wing panels DELIBERTLY too LONG.

Do it in such a way that slitting the covering and hand sawing out any excess ones would be a simple modification. Removing them so you wind up gluing rib to rib works very nicely.

At 72, I like doing old stlye stuff also.


Rich

29erJuliet

I know...I woke up this morning with that same thought...make the wings longer and then if I have to, hack off a few bays. It's fun doing it this way...I swear it!

thanks bud