Please note: officially, we have discontinued the fork assembly that we were making specifically for the Sonex, but this modification can still be made using one of our other tailwheel fork systems. We recommend the following slate of items from our site for this upgrade:
Here at Flyboy Accessories, we have been making and selling an upgraded tailwheel fork designed for Van’s RV aircraft for years. It recently came to our attention that there was a great need for a tailwheel with similar advantages for smaller planes like the Sonex.
We created the Screaming Eaglet tailwheel, a compact version of our original Screaming Eagle Tailwheel that is built on the same reliable locking mechanism found in most RV tailwheels.
Why should I upgrade?
If you’re flying a Sonex now or have a Sonex kit, you’re probably familiar with the tailwheel assembly. Whether it’s the new machined tailwheel assembly or the original welded caster setup that shipped with earlier models, the Sonex tailwheel assembly, like many small aircraft setups, does not full swivel. This allows the manufacturer to cut costs, but comes at the price of several on-the-ground performance drawbacks.
If you’ve flown on one of these tailwheels or handled an aircraft on the ground, you already know what these drawbacks are: excessively wide turning radius on taxi, difficult ground handling when pushing into your hangar, not to mention the crushing sense of inferiority you experience when you watch one of your RV-flying buddies whip their machine into a zero-radius turn for preflight.
Benefits of the Screaming Eaglet Fork
The ability of the fork to unlock and swivel allows you to make zero-radius turns from the pilot seat, and makes the aircraft a breeze to handle on the ground in and out of the cockpit. What’s more, the Eaglet increases obstacle clearance of the tailwheel vs. the older style welded caster setup and matches that of the newer style machined tailwheel.
The mechanism of the Eaglet is based on the same locking pin mechanism flying on thousands of RV’s and other aircraft. It’s simple, reliable, and effective.
What happens when I install the Eaglet?
Installing the Eaglet will allow you the full benefits of a high-performance full-swivel tailwheel, but before you go flying, there are a few other issues that you will want to address.
First of all, unless you’ve already made the relevant modifications, your Sonex does not have differential braking. We HIGHLY recommend that you install a good set of differential brakes before flying with the full swivel tailwheel.
The way that the swivel mechanism is designed, the locking pin will disengage and unlock past a certain angle of deflection, so it’s possible to make tight turns, including having the tailwheel unlock completely when pushing the aircraft backwards into the hangar. During normal ground operations, the tailwheel should remain locked in the steerable position.
If you’re replacing the older style welded caster fork, you may notice that the Eaglet will slightly raise the tail. This could potentially change your angle of attack on takeoff, which we will address later in this post.
Installing the replacement fork
The Screaming Eaglet unit is designed to fit the existing tail spring on your Sonex. You will need to measure the diameter of the aft end of the tail spring and order your mounting socket accordingly. Most airplanes this diameter is .625″ or .635″. This diameter should be held constant for the aft two inches of the tail spring.
You can find more information on installing the tailwheel (as well as a wealth of information on the tailwheel mechanism) in our Tailwheel Maintenance Documents, specifically our document Changing a Mounting Socket.
Ancillary modifications
Making the necessary modifications will be quite a bit easier if your Sonex project is still in construction, but it’s not out of reach to make the modifications to a flying airplane (although you’ll want to land it before making any exterior modifications).
The modifications that we recommend to a Sonex owner looking to upgrade to a full-swivel tailwheel are these:
Step 1: Toss that junky old tailwheel setup and replace it with a Screaming Eaglet Complete Unit.
Step 2: Install a good set of differential brakes. Click here to see plans for a heel brakes setup from our Onex test pilot Todd Reifers.
Step 3 (Optional): If you have an issue with angle of attack after your tailwheel is raised, you can correct this by installing larger diameter mains.
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