When it comes to flaps, people usually ask about stall speed. It's not the right question.
How do Performance STOL flaps effect takeoff and landing speed? That's the right question. Double-slotted flaps decrease an aircraft's stall speed, but when deployed in short-field conditions it's the decrease in takeoff and landing speeds that matters. That these flaps shave speed without increasing the plane's deck angle on landing completes the picture: Performance STOL flaps are the most effective STOL wing modification for Super Cubs and Cub-type experimentals operating in the backcountry.
On August 1, 2017, Airframes Alaska finalized the purchase of Performance STOL flaps. The flap business moved to Alaska and took up shop alongside Alaskan Bushwheels on the Birchwood Airport in Chugiak. Airframes Alaska is currently taking all flap orders, with both experimental and certified flaps now in production. Current lead time is four to six weeks for experimental flaps and four months for certified.
The first double-slotted direct replacement for the stock PA-18 flap, Performance STOL flaps represent a broad jump forward in the short takeoff and landing performance of certified Piper Super Cubs.
The STC'd flaps come in a two-hanger configuration with the flaps extended inboard to the fuselage. As a bolt-on replacement the installation includes only minimal fabric work (cutting only, no repair).
Certified Performance STOL flaps are approved on these models:
- PA-18, PA-18 (105), PA-18 (125), PA-18 (135), PA-18 (150), PA-18A, PA-18A (135), PA-18A (150)
Certified flaps ship freight from Alaska.
$5400 - $8400
Performance STOL got its start conceptualizing flap systems for experimental backcountry aircraft pushing the limits of short-field flight. With more than 100 sets now flying, it was the focus on slow flight by experimental pilots that helped make these double-slotted flaps the community's leading STOL mod.
Airframes Alaska builds all experimental double-slotted flap systems custom to the individual airplane.
- Two-hanger: $5400
- Three-hanger: $7400
- Four-hanger: $8400
Experimental flaps ship freight from Oregon.
Frequently Asked Questions
How much reduction in stall speed can I expect to see?
FAA flight tests showed a 3-MPH stall speed reduction in the two-hanger configuration. More relevantly, in real world applications we're seeing a 4- to 5-MPH reduction in landing and takeoff speeds.
What is the greatest benefit of the Double Slotted Flap system on a Cub?
Slower landing and takeoff speeds at a flatter deck angle. This gives you increased visibility and shortens takeoff distance since you do not need to be at a high angle of attack to rotate.
How much does the certified Performance STOL system weigh?
The certified double-slotted flap system for the stock Cub wing has a replacement weight of roughly 12 lbs over the OEM single-flap system.
What's the lead time for new orders?
The lead time for new experimental orders is approximately four to six weeks. The lead time for certified double-slotted flaps is four months. Airframes Alaska will begin building flaps for existing certified orders in late August. There are currently 20 orders on the waitlist.
Can I put Performance stol flaps on a certified pa-12/14/20/22?
At this time Performance STOL flaps are only STCd for PA-18s.
How long does installation take and What does it entail?
Depending on the setup, it takes the average mechanic or homebuilder 8 to 12 hours to install Performance STOL flaps for the first time. Installation includes limited riveting and drilling. In most cases, installation requires only minimal fabric work (cutting only, not repair). View complete certified installation instructions here.
Are there any changes to the fuselage, flap handle, internal wing, cables, or bell cranks?
No. The STC does, however, include the option to shorten the flap handle during installation in accordance with drawings included in the flap manual.
Does the new Double Slotted Flap system require more force to deploy than the stock Piper flap?
We have not noticed any change in the deployment force.
How does the double-slotted flap system compare to flying with slats, slots, cuffs, or VGs?
Most leading edge devices work by delaying the stall to a higher angle of attack. You can fly slower but only by increasing the angle of attack, which reduces over-the-nose visibility during landing (and makes little difference during takeoff).
Trailing edge devices, on the other hand, allow you to fly slower at a lower angle of attack. This makes flap modifications much more desirable for pilots who want STOL flying, not just slow flying.
ordering certified flaps
It's straightforward. Fill out the Certified Performance STOL Flap order form and send it in. We'll confirm the details and go over your flap build timeline. Once the required $1000 deposit is received, we'll put you in the queue. You'll get a heads up when your flaps go into production and when they're finished.
ordering experimental flaps
It takes a few extra steps on your part. Fill out the Experimental STOL Flap order form and measurement sheet. Every set of experimental flaps is custom built for the specific aircraft, so we require full pre-payment at the time of order. Once that's received, your flaps will go into production.
Contact Airframes alaska
Want to know more about Performance STOL flaps? Give us a call at 907-331-4480 or fill out the form below. Airframes Alaska is open Monday through Friday from 7am to 5pm AKST.