Originally Posted by blackshire

That makes sense, since the model's grid fins' airfoils are really narrow flat plates, which are face-on to the airflow. (I'm not knocking the KZ-1 kit's quality; properly scale-proportioned grid fins are hard to make at its scale.) If the model's grid fins were swept back, it might exhibit more positive (faster-correcting) stability, as it would if swept-back solid plates (or a conical stabilizer) were fitted to the model instead. Also:

If the same model was fitted with scale-proportioned grid fins (whose "strip airfoils" were truly thin strips parallel to the airflow), and if it exhibited a lower level of stability (taking longer to respond--with less restoring force--to perturbing forces) than it has with its current grid fins, that would suggest that the narrow "flat plate strip airfoils" produce ineffective lift (because of the Reynolds Numbers at which such tiny airfoils operate, at the model's airspeeds). Another possible cause for such behavior, if such was observed, could be "choking" of the airflow that 'tried' to pass through the grid fins' airfoils, because they were so closely-spaced. (I think this would be a less likely cause, if such behavior occurred.) Determining the characteristics and capabilities of grid fins on model rockets would be an interesting NARAM R&D project...

Originally Posted by Scud-B

My parts arrived today and I'm pleased. I've worked with 3D printed items quite a bit over the years as part of my N scale train hobby but FUD is the most common material there and detail is normally pretty high. The Falcon 9 parts are very robust, something FUD really doesn't allow, and I think the price is fair considering what you get.

I have some work ahead of me to smooth things out but I think they'll really add an extra dimension to this already pretty high quality kit.

Originally Posted by Scud-B

FUD = Frosted Ultra Detail. It's a Shapeways specific resin/plastic which produces very fine details at the expense of being brittle. Still, very thin walls are possible and people have been able to print slightly oversized representations of 1/160 rivet heads on some of their models. It's very expensive in my opinion and it's okay for trains but wouldn't likely survive the rigors of flight for very long.

Originally Posted by Scud-B

That's very interesting, I had assumed all of the Falcon 9 with Fairing kits were pre-printed with that detail.

Originally Posted by MarkB.

Comrades,

Here's a picture of what I got in the mail. Two of the legs are right-side-up as are two of the grid fins. I agree that the printing is much improved over where it was even a few years ago. The printing of these parts is similar to the PVC printing used on my prototype K-41 Mercury escape tower

The picture washes them out a little, they are really ivory colored and will need to be painted. Prime with filler primer and then a coat of Gloss White. Fit is OK-- they will need to be sanded to more closely confrom to the rocket. I'm going to wrap the tube with 220 wet/dry and sand lightly until they conform. I'll probably paint first, then sand, then epoxy them on.

I note that my version of the Falcon does not have the grid fins pre-drawn on the body wrap.