jansGliding

Hi guys

has anyone ever built a gentle/sophisticated lady with just the dihedral and No polyhedral??

if so did it fly any better? or worse


regards

slopemeno

My Feedback: (2)

I've seen several versions of what youre asking about. The problem is that the Gl flys pretty slow no matter what, so its not like youll be out doing all manner of aerobatics. However, that being said Ive seen the following:

100" polyhedral gentle lady. Had trouble turning due to short tail moment.

flat wing with ailerons, 2 meter. Seen a couple by a couple of different builders. Fly pretty nice for what they are.

60" dihedral only, rudder elevator ship. Kinda racy lines actually, the owner "Willy" called it his slope version.

A fiberglass slip-on-nosecone-over-balsa fuse by the same Willy above. This fuse was mixed-and-matched with all the different wings.

A stock Gl built with a geared Kyosho AP-29 motor and a smaller 8-cell pack that flew well.

My own Electra, built as a glider. Heavy but flew great.

A GL fuse, with,get this, a bagged 60" NSP Sparrow wing. We goaded the owner to keep making faster and faster passes at the slope until the repaired crease in the bagged wing let go and the owner managed to land with about 45 degrees of dihedral. Nailed the landing too. Flew really well for a sloper.

So, you can see that anything will work, to a degree, but if I were you I would build it stock and concentrate on keeping it light and strong. Replace any questionable wood.
Oh yeah, and Willy. He passed away a few years ago and they managed to fit a Gl in the coffin with him. Kinda fitting.

FLYBOY

My Feedback: (11)

I have done it, put ailerons on it. It sucked. My friend Jim used less dihedral, and it was ok, but not great. The airfoil used and the wing tends to like the poly. Flatten it out much and it doesn't seem to fly good. Never seen one work really well flattening it. It seems to make it fly like a dog.

tippodriver

I've never seen one without poly, but a mod I made to mine that made a whale of a difference was to add a turbulator spar. I used 1/8th square balsa knotched into the top of the ribs, about half the distance from the leading edge to the main spar. I flew mine a lot without this turbulator and a lot with it, so I can tell you it helps. The reason could be the turbulator effect, or the change in the airfoil with less sag in the covering between the ribs. Either way, its an easy change to make, with very little weight penalty.

forrest adams

i think that thermal sailplanes (those that work lift) should be polyhedral - it adds stability and this is important for working lift. i have built and flown straight wing sailplanes and they will thermal, but require lots more work (pilot effort) due to the decrease in inherent stability. i've always had my hands full trying to understand (look for lift) and work the available lift without needing more task associated with just trying to fly the plane. also, when the plane gets far away, and they will do this from time to time, you will have a hard time giving lots of input (straight wing planes require more) to a plane you can't see (at least, it's difficult to see it well enough to determine what input you need).

Tall Paul

I tried no poly and just plain flat... with ailerons.. on the Electra.. same wing..
Removed the ailerons, sawed off the tips at the joint and added the poly.
Both the Electra and the GL just flies too slowly to benefit from dihedral only, or ailerons.

BMatthews

Jans, I assume here that you're talking about adding ailerons to go with the elimination of the outer poly breaks? Because a rudder controlled model uses the dihedral combined with the yawing action from the rudder to induce the rolling action. If you reduce the dihedral as you suggest then the rudder yawing will not have enough effect on the remaining dihedral to produce the rolling action for a snappy turn entry. In particular at the lower airspeeds of a Gentle Lady and it's various siblings.

For ailerons on a slow flyer there's much to gain by using LOTS of differential throw in the ailerons and also couple the rudder in so right turn control input cranks the ailerons for lots of up travel, not much down travel and the rudder throw all together at once.