Two questions regarding two addons.

[pete.dakota]

I'm going to put this all in one thread, if you'll indulge me.

1] The Deltaglider IV. this is something I've always noticed but only now thought to ask about. When landing the DGIV, after main gear touchdown, the nose seems to "snap" down the ground within a single frame and then bounce around a bit. Whereas with other plane addons the nose comes down slowly and it's decent can be controlled with the elevators. Has anyone else noticed this?

2] X-15 v2. I've been having fun with this one recently. One thing I've noticed, though, is that the flight surfaces create A LOT of drag when deflected. Even small inputs with the stick can cause a lot of deceleration. Inputting some roll can sometimes cause acceleration to jump from -1m/s2 to -8ms/2. This seems very unrealistic to me and can cause the X-15 to fall short of it's runway if lots of corrects are made on approach.

Thanks for any feedback.

 

[pete.dakota]

OK. I've discovered what the problem is with the DGIV. It's caused by the 'ground effect' that simulates head tilt back and forth with acceleration and deceleration during landing and take off. Simply turning that effect off in the DG customization fixed it.

 

[Usonian]

Even small inputs with the stick can cause a lot of deceleration....This seems very unrealistic to me and can cause the X-15 to fall short of it's runway if lots of corrects are made on approach.
Thanks for any feedback.

It is true that turning the X-15 causes a lot of drag and loss of lift. I can not say how acurate the add-on performace is, but it does a pretty good job of replicating the typical landing pattern shown on page 2-9 of our manual. This illustration is reproduced from the actual 1962 X-15 Flight Utility Manual. So I am guessing the add-on's drag and loss of lift in a 45 degree bank is roughly accurate. Close enough for (virtual) government work. The X-15 is most often described as a brick with wings - high drag and low lift.

 

[pete.dakota]

It is true that turning the X-15 causes a lot of drag and loss of lift. I can not say how acurate the add-on performace is, but it does a pretty good job of replicating the typical landing pattern shown on page 2-9 of our manual. This illustration is reproduced from the actual 1962 X-15 Flight Utility Manual. So I am guessing the add-on's drag and loss of lift in a 45 degree bank is roughly accurate. Close enough for (virtual) government work. The X-15 is most often described as a brick with wings - high drag and low lift.

I don't mean loss of altitude of drag in a bank. I mean when the flight surfaces are actually being deflected when input comes from the stick. In a bank the X-15 performs just as I would expect it too. Test it yourself. Attempt a flight and a landing. When in thick atmosphere simply give around 50% right aileron and look at your deceleration. It will jump up a LOT. I'm talking 3 or 4x more drag.

The manual is great, and realistic descents, approaches and landings are possible and don't seem cheated at all. Other spaceplanes in Orbiter, however, don't create anywhere near as much drag when the flight surfaces are deflected. It seems quite unrealistic.

Brilliant addon otherwise

 

[Usonian]

I apologize for the slow responses. I have done some quick comparisons between X-15 and Space Shuttle (Shuttle Fleet) and I now get your point.

The problem may reflect some limitations with Spacecraft3 vs. the Shuttle's custom DLL. Although I have grown wary of "blaming" SC3 for some quirk in one of my addons - the shortcommings so often trun out to be my own.

Spacecraft3 allows one to specify three attributes for a control surface:
the area, the attack point (reletive to CoG) and the "maximum change in lift when fully deployed" (as stated in the SC3 manual). For area and attack point I used the actual values for X-15. I had no way of guessing on the "maximum change in lift" so I stuck with the default values.

Other programmable values that may cause the deceleration are Principle Moments of Inertia, rotational drag, drag coefficient on the X and Y axis and bank moment scale. As time permits, I may try "jiggling" all these variable to see what happens. It took quite some adjusting to get the current performance.

I would be delighted for you to perform your own experiments and report the results. I am an architect IRL and my actual knowlege of aerodynamics is shockingly small!