STALKERV6 #29 Doors

As cool weather approached for #29's first winter as a completed car, thoughts turned toward modifications that would make the car a bit more comfortable for occasional drives on mild winter days.

Though of no serious consequence in warm weather, the blast of slipstream entering the cabin through the "door" area would be formidable as the heat index slipped toward the freezing mark. The bodywork of the STALKERV6 is clever and functional in its simplicity but it doesn't lend itself very well to adding doors and windows. There are complex shapes at the trailing edge of the cowl, and the windshield uprights do not provide much area for attachment of windows. Then there is the need for entering and exiting the car that has to be accommodated. And any additional bodywork must be rigid enough to withstand the buffeting created by the slipstream cascading around the front wheels and up the side of the car. All these factors combine to present quite a challenge for the builder who considers adding wind protection to the STALKERV6 cabin.

A study of doors that have been attached to several versions of Seven-ish cars reveals a wide variety of schemes for solving the design challenges of buttoning up these little cars. Builders have utilized fabric, plastic, metal, and who knows what else in an attempt to ward off the elements. Since I have no intentions of making #29 an all-weather car, the design priority of my attempts at doors and windows was to provide wind protection for about four or five months of the year. Aesthetics are important but not the prime concern, and since I anticipate leaving the doors in place for the duration of cool weather, the ability to instantly pop the doors on or off was not a priority.

Michael and I did some, uh, wind tunnel testing on back roads at various velocities in an attempt to determine the origin and direction of the major drafts through the cabin. By experimenting with a piece of plywood, we found that a window just below eye level and extending back to the shoulders would eliminate the most annoying wind buffeting. The area at the windshield/window junction did not contribute to buffeting so that area is of cosmetic concern only.

I decided to build a door and window unit for the passenger side in order to test our findings. Since I have background in aircraft aluminum fabrication and the local Lowe's had a pretty good assortment of aluminum odds and ends, the metal working tools were dusted off and fabrication begun.

A frame was constructed with 1/16" x 3/4" x 3/4" angle and connected together with gussets and countersunk flush driven rivets. The door skin is 0.020" aluminum from Lowes flush riveted to the frame. Tabs and brackets were fabbed so the door could be secured to the car using existing body panel screws. The tricky area was the member at the leading edge of the door; this required several cuts in the angle flange in two places so the angle could be forced into an "S" shape. Gussets were added to the curved portions of the angle so the desired shape would be retained, and the top of the member attaches to one of the windshield bolts.

The window is 1/8" plexi from Lowes and resides in a frame constructed from 1/16" x 1/2" x 1/2" angle and 1/8" x 1/2" strap. A combination of screws and pulled rivets secure the window in a fashion so the window can be removed from the door if repair or modification is required. The trailing edge of the window is clamped to the rollbar and the entire assemble has proved to be very stable and rigid in the slipstream. No means of folding the window is present since the passenger can enter the car from the driver's side. The window was sized so the top of the frame would be below eye level, and the front of the window tapers down for increased forward visibility. And.....I though the windows just looked better with the taper.

Road tests were very promising and protected the passenger from nearly all wind buffeting. The only noticeable air flow was the usual convertible back draft coming through the roll bar. Encouraged by these tests, I proceeded with the fabrication of the more complex drivers door and window.

The necessity of leaving a means for entry into the car makes the driver's door considerably more challenging to design and build. The entire window can't fold down because of the rear fender. A sliding window is difficult because the doors have "warp and twist" so they will conform to the different angle of the windshield and rollbar. And, of course, whatever scheme is settled upon has to provide a window that doesn't rattle in the wind. After considering many, many ways to provide a moveable window or swinging door, I decided to merely build a mate to the passenger door and depend on timely inspiration when it became necessary to build the window.

What eventually transpired is the design you see above. A stationary upright carries a fixed rear quarter window and provides a stop for the folding window. The upright was located so the window could fold down without hitting the fender. Another stop was added to the upright at the windshield to stiffen the structure and accommodate a latch.

The window closed..........

   ........and open.

Entry into the car is, well, ok as long as the occupants have fairly long legs. But since the car probably won't see extensive use while the doors are installed, more than likely this arrangement will be workable.

The latch is a spring-loaded pin made from a piece of stainless welding rod, a small spring, and an 1/8" wheel collar from the R/C plane junkbox. The pin fits into a hole in the window frame. Since the window is warped into position when closed, the trailing edge of the window doesn't require a latch since it is held tightly by tension on the window.

Detail of the quarter window.

I was concerned about the doors creating such a restricted space that comfort would be compromised unacceptably. However, since the STALKERV6 cabin is wider than the run-of-the-mill Seven clone, I found that the doors do not create a problem with elbows when they are attached to reasonably-sized folks. The driver can still rest his elbow on the door sill and the steering wheel can be turned with gusto without fouling the door.

Update: I installed a plexi screen on the rollbar in an attempt to stop the back draft of air into the cabin. It proved to be ineffective and has been removed from the car. I suspect it was merely pulling air from the flow over the windshield back into the car and it seemed to introduce some turbulence of its own.

Summary: The buttoned up Stalker is rather cozy! As proof of the more stable air in the cabin, I now occasionally catch a whiff of carb fumes migrating through the firewall when the throttle is stomped. Road noise is a bit more noticeable since my outboard ear isn't being pounded by the wind.

This project shows considerable promise; I consider the present doors and windows to be prototypes, and the design will allow evolution as desired. If the doors prove acceptable this winter, I may pursue more sophisticated units built up out of fiberglass so the contours of the cowl can be continued into the doors along with elbow recesses. At the very least, these doors will probably be painted green so they will blend a bit better with the car. The doors can be removed from the car in less than five minutes by removing ten screws.

The construction of the aluminum doors was by far the most challenging part of the Stalker project, much more demanding than any of the standard bodywork! So time will tell if this little project was worth the effort and it will be interesting to see if the doors are installed next winter. I will update this page as miles are accumulated this winter.

By the way, there are some neat little self-contained heater cores with motor..........

Update 10/24/06: The doors on #29 are about to be installed for the third winter. The door project has proved to be an unqualified success and makes the car much more comfortable in cool weather, especially with the heater. Matter of fact, each spring the doors have been installed, I've been tempted to leave them in place for the summer since they reduce fatigue from wind buffeting so much. The ride is just a lot more pleasant when the turbulence coming into the side of the cabin is eliminated. But...each spring the doors have come off since it just wouldn't be, ah, acceptable to drive a STALKERV6 in hot weather with a closed-in cabin. I still haven't gotten around to painting the doors.

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