Wingspan: 50 in
Length: 38 in
Wing Area: 275 sq in
Weight: 8–9 oz
Wing Loading: 4.2–4.7 oz/sq ft
Airfoil: Drela AG-05 to AG-08

Mountain Models DL-50

Sharon with DL-50

The DL-50 is a 50-inch entry-level DLG, designed for the beginning builder and flyer. It uses only two channels, so it is inexpensive and easy to fly. The kit is manufactured and sold by Mountain Models. The complete instruction manual is on the Web page (click the "Manual" link).

DL-50 launch

The DL-50's wing is a foam core with a fiberglass skin. It uses carbon fiber rods as spars and carbon fiber tape as reinforcement, with epoxy and Minwax Polycrylic as adhesives. The fuselage and tailfeathers are of conventional balsa/plywood construction, joined by a carbon-fiber boom. The fuselage is laminated with fiberglass.

This is a great training aircraft for hand launch soaring. With the CG in the right location it launches straight, floats well, and is easy to control. The discus launching technique takes practice, but is very addictive—it's hard to stop flying and go home, because "just one more flight" is so easy to do.

Here's a review of the original version of the DL-50.

I ordered my DL-50 kit on 29 May 2007, started the build on 16 June, and finished on 1 July. The construction process was simple and fun, and the total build time was only about ten hours. The maiden flight was the evening of 1 July.

Here are some pictures of the completed plane:

DL-50 DL-50 showing flat antenna DL-50 showing cruciform tail

The radio is a 3-channel Hitec Neon 72MHz radio system, including a single-stick transmitter, Micro 05S receiver and two HS-55 servos. The Neon transmitter is small and light, so it's easy to hold on to when you're spinning in circles launching a glider. The range of this radio system is about a mile, much farther than the range at which a 50-inch airplane is visible.

The flat receiver antenna (the gold-colored thingy on the right side of the fuselage) is a short base-loaded Berg 'sticky antenna' from ALL e RC. This replaces the meter-long wire antenna that comes with the receiver.

The flight battery is a 5-cell 6V NiMH pack. Battery packs are available from many vendors, such as CheapBatteryPacks.com, in a variety of capacities. A 250mAh pack will provide around three hours of flying. Any 4.8V or 6V pack that weighs less than 30g will work just fine.

AUW (all-up weight) of the airplane is 8.15 oz; the advertised weight is 8–9 oz, but some builders have managed weights around 7.5 oz.

During its first high-altitude flight, I quickly realized that the pale pink foam core of the DL-50's wing is almost invisible against a pale blue sky! I've painted a wide black 'invasion stripe' on the bottom of the right wing, and the airplane is now much easier to see.

The total cost to get this DL-50 in the air, including building supplies and all electronics (but excluding shipping and AA batteries for the transmitter), was $178 in mid-2007:

DL-50 kit$70
Hitec Neon radio system$60
flight battery$6
sticky antenna$12
Minwax Polycrylic$5
6-minute & 30-minute epoxy$10
foam brush, thin & thick CA$10
clear spray lacquer$5

The clear spray lacquer was used (just a light dusting!) to waterproof the balsa tail surfaces.

Here are some long discussion threads about building and flying the DL-50: