The Star Bee
Tail Group

VERTICAL FIN

Now that we had all our hardware neatly cataloged, it was time to get back to working on the Star Bee tail group. All the components had been previously painted, so the last finishing touch was to add the ultralight registration numbers. It is much easier to do this with the vertical fin flat on a table-top then trying to get things aligned once the fin is mounted! This venerable USUA registration number was used on our old Quicksilver from 1982-1988 and on the prototype Gyrobee from 1990 through 2004.
 
 

HORIZONTAL STABILIZER HALVES

The assembly of the horizontal stab components was somewhat contrary to what Star Bee had intended and you can use your own judgment as to which approach to take. The fundamentals - the supplied AN4 hardware is used to secure two pairs of stainless (thin) mounting brackets (one pair on top, another on the bottom) and the strut and bracket on the lower side of the stab half. Gently tighten the mounting brackets so the free ends permit the inboard end of the stab to rest flush on a flat service. NOTE: since the stab is an asymmetric section, the forward bolt must be longer then the one toward the rear. Star Bee will have supplied two lengths of AN4 mounting bolts, so keep track!

Our modification was to use an AN470 flat washer under each bracket to provide a broader bearing area between the bracket and the fiberglass as shown in the detail below. We also used a pair of AN970 washers at the mounting point for each of the strut brackets for the same reason.

Once the stab halves are complete, use one to mark the mounting holes on the vertical fin. This should be done prior to painting the fin. We overlooked that detail and had to use the CAD drawings of the fin to locate the mounting hard points. The mounting holes should be located with an angle of incidence of -2 to -5 degrees relative to the base of the fin. We settled on three degrees.

VERTICAL FIN MOUNTING

The 3/16 inch thick mounting brackets, three on a side, go along the lower edge of the fin. The long arm of each bracket is vertical so that, when the brackets are mounted, the shorter sides will be flush with the bottom of the fin as shown here. Three AN3 bolts on each side clamp the vertical fin to the tail boom using three straight aluminum pieces below the tail boom:

It obviously takes three aluminum strips to do the mounting, but Star Bee will have sent you a total of six! The other three need to go under the brackets, raising the stab 3/16 inch above the tail boom. This is done to provide clearance for the AN3 bolt at the top of the bracket that will support the lower end of the struts for the horizontal stab halves. You can see this bracket just aft of the center mounting bracket:

TAIL GROUP ASSEMBLY

The next step was to mate the horizontal stab halves to the vertical fin:

Again, we departed from Star Bee's intent by using AN970 washers under each of the four mounting brackets. This left a 1/16 inch gap between the inboard end of the stab half and the vertical fin, but we preferred to use the washers to spread the clamping load.

STABILIZER SUPPORT STRUTS

When you pull out the stabilizer support struts, you will be shocked to discover that the two pieces of tubing are too long (slightly) and have no holes drilled in them. This is one of the few places you will have to be a real homebuilder - cutting and drilling!

 

• Assuming the stab halves look approximately symmetrical, as they do here, use a string to measure the distance between the pairs of bracket holes on each side.
• Measure 3/8 inch inboard from one end of the two strut pieces and drill a centered 1/4 inch hole through each strut.
• Take the average of the two hole-to-hole measurements and use it to drill a second 1/4 inch hole through each strut with the same orientation as the first.
• Cut both struts 3/8 inch beyond the hole you just drilled.Deburr all holes and cuts on both strut
• Slide the lower strut support bracket until it is just forward of the rearmost attachment bracket for the vertical fin and secure the AN3 and AN4 clamping bolts.
• Mount the struts to the strut brackets using the AN4 hardware provided. The bolts are just slightly too long, so use a second washer on either end of the bolt.

The end result will be a VERY solid tail group. Once everything is in place, everything is quite solidly triangulated. There is a lot of rudder area so less pedal should be required on takeoff. There is also plenty of horizontal stab area, complete with an airfoil section that sits in the propwash. All in all, no reason to think that it shouldn't be very well-behaved in flight.
 
 

Session time: ~5 hour      Total Time: ~21 hours