Monthly Archives: January 2015

Flight Dynamics

The flight dynamics results are in – and it takes a lot of work to fly the Dropship!  Unfortunately we have not been able to demonstrate controlled flight maneuvers yet.  If I can’t understand how to fly it, it will be exceedingly difficult to explain to the AFCS.

Initially I thought this may be Dutch Roll. However, we are a lifting body and my experience with Dutch Roll has been limited to swept-back wings. But it does affect the vertical and longitudinal axes.

DuchRol4[1]

After searching online, I ran across “coupled roll-spiral mode” which is a condition I was not previously aware of. Anyone that can build a dampening routine for this mode is welcome to contribute! In fact, based on the article below, it is likely a combination of the two effects.

Time keeps marching on and I have gotten in a little over my head with this flight model and all the necessary changes that I hadn’t accounted for.  As a result I removed all the availability on the booking calendar through April 10.

Lunch Update

Made a lot of progress over the weekend determining the surface area, surface normal, hinge axis, etc. for the flight control surfaces. This robust system will allow us to make any number of discreet channel controls in any configuration!

However, we are running into problems with the movie model again… we already identified that the engines were above the CG (which won’t work once we get to space) but now apparently the lower portion of the X-tail is as well!

Prop2[1]

1-26-2015 1-23-15 PM

Wind Tunnel

Sorry I haven’t been posting lately, I have had my head down working on the flight dynamics for a week.

At first I thought the tail design for the Dropship was a V-tail and an inverted Pelikan.

149px-Tail_pelikan.svg[1]

That would have worked with the existing wind tunnel algorithms from Rise but unfortunately what we are looking at is more like the X-tail concept which is a whole bag of worms with 4 discreet channels that can result in pitch, roll, yaw, and spoiler motions.

2015-01-11_20-01-52

So I am rewriting the wind tunnel piece by piece, taking it to the next level in every respect. For example we used to only count the vertical stabilizer and rudder sections in the weather-vane algorithm. Now I have it computing the clean (gear up) and dirty (gear extended) profile drag and weighted arms for both Z (for yaw) and Y (for roll) tendency!

windtunnel.drag.profile