View Single Post
Old Aug 29, 2009, 12:07 PM
F7X is offline
Find More Posts by F7X
F7X's Avatar
United States, NV, Sparks
Joined Oct 2004
1,182 Posts
Weights, Wing Loading, and Density Altitude

This is the most critical part of the design. We must keep the wing loading down and here's why: Out club field is at a 5000ft elevation. And while that doesn't sound too bad, density altitude in the summer can exceded 10,000ft! The ground speed of the models is much higher up here. We are always caught of gaurd by the way our aircraft slow down and float when we fly at AEF versus here.

The Grand Junction Modeleers don't have an 800ft long, 50ft wide runway, Our runway is 400ft long and about 20ft wide. I'm not complaining! Many of you fly off dirt, or grass or streets. I'm very lucky to have such a nice facility, but it does make for a bit of a challange with more high performance aircraft. And I'll tell you right now, that there is no way a 12s CARF Spark can make it in and out of that runway on a hot, calm day. Maybe out... but not in without going in the weeds. Even a BVM Electra would be pushing it.

After adding up the weight of all the "guts", we've decided that we can build the jet at our around 10lbs AUW. At the most 10.5lbs. With a wing area of 800 squares, we will get a wing loading of about 28.8 to 30.24 oz per sqft. Perfect!

If we can reach our goals, this jet will weigh 1.25lbs less than a Spark, and about 3.5lbs less than an Electra with similar power systems.
F7X is offline Find More Posts by F7X
Reply With Quote