For this event, the only suitable engine is either the 13mm 1/2A3-2T, or the 18mm 1/2A6-2.

For this event, you are allowed two flights, the two flight times added together. You can use a second model for the second flight if you want. ONE of the two flights must be returned (and it has to be a qualified flight that is returned). So if you lose your first flight (or DQ), you need to be sure to fly your second flight more carefully so you get the second flight back, and that it is qualified.

Use this link for a good page of tips and information: http://ojames3.tripod.com/tccnarcontesttips/30PD.html

A couple of plans for BT-5 (13mm) models are shown below. Note that they do not show a launch lug, so do not forget to add one.

You may have more success using a BT-20, or 18mm model, and a somewhat larger parachute than can be fit inside of a BT-5 model.

A normal Estes type of parachute is pretty thick. So to fit a larger diameter parachute into a limited tube space, it is best to use a thinner material. A lot of contest fliers use 1/4 mil drop cloth plastic. But it is harder to find those lately. Another source, not as thin, is Dry Cleaner bags, or cheap Ponchos as you would find at a Dollar Store.

Among kits that would be suitable would be the BT-20 sized Estes Bandito, and Firehawk.

If you have a Wizard, Yankee, or other BT-20 model meant for 18mm engines, you could use that too. Though with an 18mm 1/2A6-2 engine that is a somewhat heavy engine casing to come down with. But, it will definitely work and could have a shot.

Estes BT-5 kits that may be suitable are the Gnome and Puma, if you have them.

It is a good idea to have a second model, even if it is not nearly as good as your [primary model. Indeed you might not want to have the back-up to be as good as your primary. For example let's say you have a great flight that hits a thermal and flies away. You will have a really good duration score, but you HAVE to get the second flight back or your total score will not count. So, you could even have something like an Estes Alpha as a back-up and fly that for a short flight to make a "qualified" flight to score a return.

	The plan at left is for a BT-5 (13mm) model, from the ASTRE NAR section. At 10" long, it would be a bit short for PD, it would be better to be about 12" long or so. Here is a link ink for a PDF version of the plan.
	The plan at left is for a BT-5 (13mm) model, by Trip Barber. it is meant for Streamer Duration, ut also is fine for PArachute duraint if made a bit langer, at around 12". Note that the shock cord is mounted on the outside, keeping the inside uncluttered. Here is a link ink for a PDF version of the plan.

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