I built 2 hand launch chrysalises and I found the design was great and everything was strong except for the v-tail section of plane. I noticed on the 2M version that it looks like the same construction was used in this area, with the exception of no lightening holes. I am concerned about the area not being strong enough.

One of my main reasons for wanting a 2M plane is that I want a tougher plane. What have you done on the 2M to help out in this area?

From : Don Stackhouse

First I need to clarify a few things about the hand-launch Chrysalis.

The HLG Chrysalis tail (either the conventional or the V-tail version) is quite strong already in relation to what it has to do. The strength of the tail panels has NOT been a problem area. We have had a few cases of tail flutter on launch, but all the ones I'm aware of were traceable to slop in the pushrods and control linkages. This can induce flutter in almost any design. In the case of the 2-meter Chrysalis, we supply steel cables in nylon tubes (specially made for us to a longer than normal length because of the long tail moment) with metal clevises, which should help make it easier for beginners to get stiff, slop-free linkages. We also have guide holes pre-cut in the formers for the guide tubes, and detailed diagrams showing how to run the tubes for both the conventional and V-tail installations.

The lightening holes in the tail are strictly optional, in both the HLG Chrysalis AND the 2-meter Chrysalis. In our tests we've found that a good Varathane paint job without the lightening holes is about the same weight as a film-covered model with the lightening holes. The strength is also similar.

Torsional loads in the tailboom are an issue. In the HLG they're sufficiently low that some strategically placed glass tape around the end of the boom in front of the stabilizer is enough to deal with the problem, but in the 2-meter it takes a little more than that. We've designed the fuselage with an additional former halfway between the wing and the tail, and the former at the leading edge of the tail (now called F5) is left in place, not broken out to make room for the pushrods like in the HLG version (another advantage of the new pushrods). This keeps the tail boom cross section from squirming around under torsional loads, which adds a surprising amount of both stiffness and strength.

OK, now that we're into structural details, I'd like to state for the record that the 2-meter Chrysalis is NOT a simple scale-up of the HLG Chrysalis. This is one of my pet peeves; even though a 2-meter and its HLG cousin might look superficially similar, I don't believe in simply scaling up or down an existing design to make one from the other. This is how folks were making HLG's from 2-meters in the early 90's, and it was our rejection of this flawed approach that set the stage for the initial success of our first "Monarch" HLG's.

Yes, many of the construction techniques in the 2-meter version would be familiar to anyone who's built a hand-launch Chrysalis. However, would you care to guess how many parts the two kits have in common?

Exactly ZERO.

The closest thing to common is that the trailing edges of the 2-meter use the same notch spacing and cross section as the inboard portion of the HLG. That's IT.

Regarding the tail surfaces, the laser-cut stabilizers and fin have basswood spars, with or without the lightening holes. We also have chordwise-grain end caps on the control surfaces to increase their strength, stiffness and warp-resistance. The tail cone is also much stiffer, in part because of the new formers, but also because of the thicker cross-section and heavier longerons and balsa skins. The pattern of fiberglass tape also plays a part, and we've included some very specific diagrams in the instructions showing exactly how to do it.

The control horns are stronger, and longer in the chordwise direction, for a stiffer and stronger connection to the control surface. They're also longer in the moment arm sense, which gives the pushrod more leverage to make the control surfaces hold still against air loads. Finally, the use of the metal clevis also gives more bearing area in the hole in the horn, which reduces slop and wear.

As far as the rest of the plane, the fuselage side doublers are laser-cut lite ply that run from the nose to a bit aft of the trailing edge of the wing. The forward ends of the basswood longerons for the tail boom glue into 2" long notches in the aft end of the ply doublers. The instructions also show exactly where to add fiberglass reinforcements in the rest of the fuselage and the wing for the best increase in strength and the least increase in weight.

The wing looks similar, but internally there are many differences. The leading edge is 3/16" birch dowel. The spars are HUGE, and there is a rear spar in addition to the main spar, not to mention the spoiler spar. The main spar is a full box on the inboard panels, with birch ply "Laser-Web" shear webs (laser-cut, and designed so you install all the shear webs in ONE STEP for each face of the spar!). In response to another writer's question, I calculated that the bending strength of the main spar is more than five times the strength of a Gentle Lady's main spar. I'd still recommend using a little finesse on the winch pedal, but it winch launches with no trouble if you use a little common sense.

A 2-meter is not a hand-launch, and it requires a different design approach in some key areas. We've done our best to address those areas in the design of this one, plus benefit from all we've learned from the hand-launch Chrysalis. Try it, I think you'll be very pleased with what you find!

Don Stackhouse
DJ Aerotech