In one of my past articles I talked about the increase in the number of warbird models that are appearing around the country. As pilots progressed in their ability to build and fly these models we saw them add more and more mechanical options to the aircraft. The first added goodie was flaps. This addition was relatively easy and posed no real problems for even the novice warbird builder. The next step was the addition of retracts and then came the associated problems of sequencing main landing gear doors. This problem I approached in a past article.

The next obvious step for the serious scale warbird builder was to incorporated the retractable tail wheel. For the longest time we saw P-51's and similar models flying around with the main gear retracted and, boy, it really looked great. But on a low, slow fly-by you'd always notice that old tail wheel hanging out in the breeze spoiling the effect of realism. Well, as some retractable tail wheel units appeared on the market we noticed an increase in the number of modelers who incorporated this feature in their ships. this greatly improved the view and the illusion of realism was almost complete. However, when the tail wheel was retracted we now saw a big gaping hole. The problem of operational gear doors once again popped up. Many attempts have been made to try to alleviate this problem. Some have been successful, some not. Of those that worked some were mechanical nightmares, thus making it difficult for the budding warbird builder to become successful.

Once again I'd like to present to you one solution I've used on my giant scale Thunderbolts. After many hours of tinkering with various methods I felt very comfortable with this solution.

The retract gear I chose to use is a Carl Goldberg retractable nose wheel unit that is used on your average .40 - .60 size ship. Some modifications have been made to this unit. I've removed the stock spring-wound strut and replaced it with a solid 3/32 music wire strut that is bent to a rearward cant. An aluminum sheet metal bracket is bent and attached to the Goldberg unit. The tail wheel strut runs through it. Just forward of this point is a small sheet metal screw that secures the aluminum bracket to the nylon retract mechanism.

One Fibeglass tail wheel door with Dubro 1/4 scale hinges and straight pins. Also seen is the 1/2A size control horn relative to the hinge line.

The doors, in this case, are made of formed fiberglass but bent aluminum sheet will work just as well. The doors are hinged with Dubro 1/4 scale hinges. Two hinges are used on each door. The brass cotter pins are replaced with conventional straight pins that can usually be found in any sewing kit. These pins are used to allow for a free pivot of the doors, better than the cotter pin method. The straight pins are retained by masking tape. I prefer using tape versus bending the pins in order to be able to remove the doors whenever it may be necessary to service the tail wheel assembly. Each hinge is attached to the doors by two 2-56 screws and nuts.

Tail wheel door mounted to fuselage, The striker plate can be seen over the rear hinge. Also shown is the spring that connects the 1/2A control horn to the sheet metal bracket.

The photos show a white piece of plastic on the rear hinge of one door. This is a "striker plate" that the gear will sometimes hit if the tail wheel is turned to that side during retraction or extension. This would happen, for example, after take off and upon retracting the gear while right rudder is being held to offset engine torque.

Aluminum sheet metal bracket mounted to retract mechanism. Note how spring mounting holes are spread apart to allow for clearance of strut when unit is retracted.

Two small (1/2 A size) control horns are attached to the doors, one on each door. These either pull the doors closed or push them open. Note their orientation relative to the doors and hinge line.

Springs are used between the sheet metal bracket that is mounted to the retract unit and the control horns on the doors. The length and strength of these springs must be played with in order to give proper sequencing. When the wheel is up these springs will want to pull the doors closed. This should only be a slight pressure. Stop blocks are installed on the inside of the wheelwell in order to prevent the springs from pulling the doors closed too far. When the wheel is down the springs will push the doors open and hold them in position.

After some trial and error, fitting and fiddling, you'll see it's not too difficult to get this system operating smoothly and reliably. I hope between my short description and the accompanying photos you'll be able to add that extra touch of realism to your warbird. Until next time... gear up and happy flying.