I've had my Chrysalis built and flying for a couple of months now and haven't ever really seemed to be able to get it dialed in. The one thing I see a lot on Ask J&D is that people seem to want to fly them too slowly. Perhaps I am guilty of the same thing..... It's tough to know how "fast" it should be flown. Tip stalls are always a problem for me, as is the ability to hold a turn.

From : Don Stackhouse

C/G and washout can both be a factor in that. Also be careful to make sure that your C/G and washout are really what you think they are. What you describe could be a piloting technique problem, but could also be a problem with washout and C/G. The numbers you mention sound correct, but make sure you're measuring them accurately (more on that below).

Out of curiosity, what would you say is the maximum bank angle and approximate circle diameter of a low (around launch height or slightly lower) thermal circle without tip stalling? That may help me get a feel for how tight a turn I can make.

That's a skill issue. Joe and I can fly 3' diameter turns with the inside wingtip without stalling, but it takes practice and some seemingly unconventional techniques. 60 to 70 degrees bank angle is a good maximum for a minimum radius turn, any steeper than that doesn't really tighten the turning radius significantly. You will need massive amounts of up elevator (about twice as much as it takes to stall in level flight!) to hold your pitch attitude in such a steep turn (due to the curvature of the airflow past the tail because of your curved flight path), but be ready to instantly release some of that "up" if anything suddenly disturbs your turning radius, reducing the curvature of the airflow. If you don't, the model will stall. It's a lot like playing a fish on the end of a line, and takes a fair amount of practice to truly master.

You only need those super-tight turns in very small diameter but fairly strong thermal cores. A more typical thermal turn is usually more like about 20 to 30 degrees bank angle, maybe 40-45 degrees near the ground where the thermals are smaller. The turn will probably be about 10-30 feet in diameter.

As far as not flying too slowly, the best technique initially is to concentrate on keeping the fuselage almost perfectly level with the ground. That's right, if the fuselage is flying tail-low, you're probably flying too slow. That's not by accident, that's one of the parameters that helped us determine the correct incidence for the wing.

I have the washout set for 3/32 to 1/8 of an inch (I've experimented with both), but I seem to have a tough time getting this exact because the wings are warped up slightly. My building surface was flat, but the way the top spar is bent in order to go from the thick inner ribs to the thinner outer ribs seems to give a bowing effect on the wing. My inner panels both sit raised about 1/8". With a LOT of time and difficulty, I've been able to get the panels totally straight using a heat gun, but I've never been able to accomplish this AND have the right amount of washout.

DO NOT USE A HEAT GUN. That's part of the problem, you can't control the shrinking process properly with a heat gun. You need to be able to heat small, isolated areas of the panel if you want to be able to truly control what's happening. Use an iron.

Also, are you familiar with the technique of sighting the trailing edge from behind to check washout? Hold the model at arm's length with the nose pointed away from you, so you're sighting exactly along the fuselage. You should be able to see the trailing edge and the lowest and highest points on the airfoil all along the wing. Rotate the nose up or down until you see the lowest point on the trailing edge (hopefully the root end) appear to exactly "touch" the lower surface. Now, look along the trailing edge and note how far above the lower surface each spot on the trailing edge is sitting. For 1/8" washout on the inner panel, the root should be touching the lower surface in your visual image, and you should see a 1/32" gap about one-fourth of the way out, 1/16" at mid-panel, 3/32" at three-fourths of the way to the panel break, and 1/8" at the panel break.

Now shift your head to one side so you're sighting along the panel break (the K1 & K2 ribs). The outer panel on the Chrysalis should be flat, no washout, so that the gap you see between the trailing edge and the lower surface is constant all along the outer panel.

This method works regardless of whether the wing is bowed or not, and with a little practice, it's extremely sensitive and precise.

Make a mental picture of the washout distribution you saw along the wing. Let's say that perhaps the middle of the inner panel had no washout, and you had 3/16" washout between the middle of the panel and the panel's outer end. Heat up your iron to covering-shrinking temperature, set it where it will be easy to reach, and sit down. Clamp the nose of the model between your knees and grab the middle of the panel with one hand. Twist it enough to force in a little more than 1/16" of washout between there and the root, then use your other hand to run the iron over both the upper and lower surfaces between the mid-panel and the root. You should feel the panel "relax" in your hand if you're really paying attention. Take the iron away and hold the wing in the correct twist for about 10-20 seconds as the covering cools down. Sight the trailing edge again and see if you now have 1/16" of linearly distributed washout between the root and the middle of the panel. If not, then re-do this step until it's correct.

Now, do the same thing again for the outer half of the inboard panel, but this time locating your hand at the panel break and heating the outer half of the inboard panel. In the example I described above, the outer half of the inner panel had too much washout, and what you just did to the inner half made the outer half even worse. It's now set at 1/4" relative to the root, so you'll need to twist about 1/8" of wash-in back into the outer half of the inboard panel to end up with 1/8" of linearly-distributed washout over the entire span of the inner panel.

With a little practice, you should be able to dial in a very accurate and perfectly linear washout all along the panel. Also, check the tip panel and make sure it's set for zero washout.

In order to get the panels flat, I have to shrink the lower and upper covering. I notice that in setting the washout according to the plans, you only shrink the top. Once I set the panel down flat, shim in the washout, and shrink the top of the covering, the panels come out bowed 1/8" again. Now I've settled for about 3/32 washout, and having both outer panels bowed 1/8" up equally (front of the panel at the end raised 1/8" and rear raised 7/32"). Is this acceptable?

That amount of bowing should have no measurable effects. The washout is critical, but the bowing is not. However, by the technique I described above, you should be able to correct both the washout and the bowing simultaneously.

There is a lot of info in Ask J&D about V-tail differential. I have one of those Focus single stick radios with built in v-tail mixing. Of course, it is non adjustable. Am I going to have success with this non adjustable mixing?

Folks make a big deal about V-tail differential. In my experience it's not that important. The Chrysalis flies fine with no differential. At worst case you may find that you have to give it a little bit of elevator correction whenever you apply rudder, something that soon becomes instinctive. You will find that you have trouble flying someone else's airplane that is set up differently from what you're used to.

For example, Joe likes to set his sailplanes up with too much differential, so that the nose drops a little whenever rudder is applied. It's just part of his personal flying style. I prefer to set my airplanes for perfectly neutral pitch, no effects on pitch attitude when rudder is applied. I find Joe's airplanes very disconcerting to fly until I can mentally shift gears and get used to the way he sets them up. I'm sure he probably feels the same way about mine, although his flying skills are so far superior to mine that it doesn't seem to take him any time to adapt.

It's very possible to adjust the differential without a computer radio. Just do it the old-fashioned way, with the mechanical linkages. Remove the servo arm (on the Chrysalis you may need to make a small hole in the fuselage side, just big enough to get a screwdriver in to the servo arm's retaining screw) from each ruddervator servo and reinstall it leaned aft about 20 degrees or so. This will give you less up travel and more down. Vary the angle to vary the differential. You will of course need to readjust the clevis on the pushrod to re-center the ruddervator whenever you reset the angle on the servo arm.

FYI I have moved the CG around here and there but lately have been leaving it right near the center of the range.

Whatever makes the airplane fly the way you like it is the correct C/G for you. However, Joe and I have found that the airplane seems to turn smoother and better with the C/G further back, typically about on the aft limit or up to about 1/16" in front of that.

Thanks for your help!

You're very welcome! I hope these suggestions help!

Don Stackhouse
DJ Aerotech