Quote:
Originally Posted by basjoos
Here are line drawings of the Questair Venture that I patterned my boattail from. Ideally I should have used a less steep angle on the underside to compensate for the road surface restricting the fill-in airflow under the boattail, but I have a steep approach angle to my driveway and didn't want the boattail to drag so I went with the Venture tailcone angle (aircraft require tail clearance for when they rotate on takeoff). To compensate, I made my rear wheel boattails asymmetric to help direct airflow under the boattail. Based on the dirt deposit patterns under the boattail, the whole setup seems to work, but it would be nice to confirm it with tufting.
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This is where the practical intrudes quickly on the theoretical
If it were not your driveway, then it would have been something you would have encountered along the way - a bad gas station transition, a severely crowned intersection, etc. I think that folks ignore the practical road conditions at their own peril! It would be a shame to spend lots of money and effort on a great performing boattail, only to destroy it on some hard object along the way. Well done!
It may be worth considering the "breakaway" characteristics of any boattail. For example, if the strongest main attachment support might somehow be located at or near the top of the boattail and if the lower attachments were relatively weaker, then any dragging of the boattail might just break the lower attachments and cause fairly minor damage. Dragging damage would also be minimized by incorporating some sort of rugged skid plate in the rear bottom of the boattail.
Another thought. One could build the boattail in two sections. The rear section could be simple, light and sacrificial. Black plastic glued to strofoam comes to mind. Just thinking out loud.