TOPIC: Wing loadings, deltas and flying Characteristics

In response to a recent blog, which included reference to my F-106, Howard Metcalfe opines that the wings are 'too small', even though they are enlarged over the full size prototype.

I have made some calculations, and given a weight of 20 g or so, the wing loading should be under 6 oz/sqft (sorry about the units, but it's what I'm use to) so I hope I'll be able to power it with a Rapier L-2X (150 mN or so), and it won't need, like Richard Crossley's Su-11 an L2-HP.

What do other modellers think? Is more area required? Deltas are pretty stable, and, with an L-2 HP behind it the Su-11's flight pattern is ballistic - it goes up and comes down pretty quickly - but I don't know how heavy the kit models come out as. Any ideas?

I had an interesting email from Brian Eastwood, who makes little CO2 rockets. He took my Delta Dart template from the blog (cheeky!) and made a 3" version. With a bit of reflex it does, he says, fly very well, resulting in a long walk .

So that's OK!

Hi Roger - this is an interesting subject.

I'm currently working on a calculator program that will attempt to address model size, weight, wing loading and drag to predict a ball park value for required Rapier thrust. Or vice versa - sizing the model from the motor. I've been looking at some of Mike S's model specs and starting to get some reasonable results.

A high wing loading will mean the model needs to fly faster but you also need to think about L/D ratio. This can be roughly measured empirically as a glide test (distance glided/height) The better the glide the less thrust needed obviously. The trouble I have is a lack of data (experience!) so if anyone wants to measure some glide tests...

Jon