The Reflex spring patent — US 7,607,615

(US 7,607,615 — “Brake for a kite” by Joseph R. Hadzicki)

Published on 17 October 2026 by Alban Kites

This page details US 7,607,615, “Brake for a kite,” filed by Joseph R. Hadzicki and assigned to Revolution Enterprises, Inc. At Revolution, the system it describes is sold as Reflex. It explains the principle of the brake, as the Reflex spring implements it, what pilots of kites fitted with the Reflex spring say about it, and who the system seems aimed at.

Diagram 1 is a teaching drawing, not to scale, made by QuadKites.org from the patent’s description. Figures 1 and 4 come from the patent.

• Title: “Brake for a kite.”
• Inventor: Joseph Hadzicki, Coronado, California.
• Assignee: Revolution Enterprises, Inc., Poway, California.
• Filed: 6 January 2006 (application US 11/327,300); published as US 2007/0170308 A1 on 26 July 2007.
• Granted: 27 October 2009.
• Term: 20 years from filing, like any US utility patent, extended by 202 days to make up for delays in examination at the patent office.
• Expiry: 27 July 2026, according to Google Patents. Google presents this legal status as an assumption, not a legal conclusion.

The patent is public: read the patent as a PDF.

The word covers three different things, which often muddles discussions. In this page, “brake” refers to the patent’s device, and “Reflex spring” to the part fitted to Revs that implements it. This page deals only with the spring; the range and the rods are mentioned only to clear up the confusion.

• The spring: the patent’s device, a spring fixed to a strut that tensions the sail (on a Rev, the vertical spars). It is the subject of this page.
• The Reflex range: the models that carry the name, such as the EXP, the 1.5 Classic, the RX and the XX. They do not all use the same rods: the EXP uses 1/4-inch rods (about 6.4 mm in diameter), while the XX rods and RX use 5/16-inch rods (about 7.9 mm).
• The 2016 launch: from that spring, pilots discuss the new generation of Revs with springs (first impressions, Revkites).

This generation changed the rods too: they are thicker, and parts from older models, without springs, are no longer interchangeable with the new ones (KiteBuilder).

The patent claims a kite fitted with a spring brake: a sail, a strut and a spring brake fixed to the strut (the patent’s standoff). It does not describe the quad-line structure or the handles, which the text does not mention. Those elements rest on older patents, the first of which, US 4,892,272, expired in 2008 (read the article on that patent).

The irony lies in the fact that the patent still in force covers an added element, the brake. A brand can keep calling its kite “patented” for that element, long after the kite’s original design entered the public domain in 2008–2009. In its 2020 video, Revolution presents the Reflex design as “patented and only available on Revolution kites.”

The patent therefore entered the public domain in July 2026 (expiry estimated by Google Patents).

The patent starts from the case of powerful kites, used with a ski, a board or a vehicle. Such machines can drag their flyer through trees and obstacles, and the text says they offer no way to compensate for gusts.

A Rev is a very different object: light (about 260 g for an EXP, according to the manufacturer) and designed for precision. The patent does not describe it. The chain it describes still applies on a smaller scale:

1. if the nose (leading edge) drops below zero angle to the wind, the wind pushes the kite toward the flyer;
2. line tension is lost, and control goes with it.

On a Rev, the loss of control mostly takes the form of a stall at the edge of the window or overhead, as the Revolution video describes. The patent aims to remove power while keeping control. The goal is not to stop the kite, but to let it come down in a glide and bring the nose back into position.

A sail’s lift depends on its shape. When the underside, the surface that catches the wind, is concave, the cambered sail produces lift upward. If that camber is reversed, the lift disappears.

The patent describes two sail shapes:

• flying shape: the sail is concave relative to its bottom surface. Wind pressure cambers it, and lift pulls the kite upward;
• brake shape: the sail is concave relative to its top surface. A rod pushes the top surface away from the strut, the sail takes a reversed camber, and lift disappears.

The brake switches according to the balance between wind pressure and spring force:

The patent gives no value for this threshold. It depends on the spring chosen and on the wind. The description states that enough wind, pressing on the underside harder than the spring, switches the brake off.

The patent does not discuss performance by wind strength. It only says that a wind whose pressure exceeds the spring force switches the brake off: in strong wind, the spring compresses, by design. The text does not claim that its effect disappears. On the ground, views differ. In a 2021 thread, one pilot supposes that Reflex only works well in light or no wind; another replies that in strong wind the spring stays compressed and acts only if the pressure on the sail is released (Club 38 group). Revolution presents Reflex as optimised for light wind (Reflex XX page).

A lift estimate, based on the orders of magnitude for an EXP (a simple calculation, not measured), suggests that the zone where the sail holds narrows clearly around the centre of the window in light wind, and widens in strong wind. This fits the views that place Reflex in light wind, without proving them.

The brake does more than cut lift. It brings the kite back into line. According to the patent, the standoff, on its own or through the force it exerts between the sail and the strut, turns the leading edge pole towards the top surface of the sail: the nose rises, the control lines regain their tension, and the sail forms a reverse-lift airfoil. The patent says the kite glides to a stop, rather than stalling or falling out of control.

• 4A: in flight, wind pressure cambers sail 304 against strut 306, and lines 310 are taut.
• 4B: the pressure under the sail drops below the spring force; standoff 308 pushes the sail away, its camber reverses, and the lines go slack.
• 4C: leading edge pole 302 turns towards the top surface (arrows): the nose rises and the lines tighten again.

Claim 18 specifies that this rotation can briefly slacken a line before it is tensioned again. For the pilot, that is the moment the line seems to float before it tightens.

The claims fall into five families:

• Claims 1 to 5: the brake alone. A spring-loaded standoff, connected to a strut, pushes the top surface when the pressure is less than the spring force. The spring can be a coil wound around the strut, with a rod extending from it.
• Claims 6 to 10: a complete kite, with sail, strut and brake.
• Claims 11 to 16: a sail that is convex over its whole extent relative to its bottom surface, with at least two struts, each carrying a standoff. The standoff can also rotate the leading edge pole.
• Claims 17 and 18: the leading edge pole turns up under the strut’s action, with control lines kept under tension. This is the part closest to flying.
• Claims 19 and 20: a spring-loaded sail that switches between two shapes depending on pressure, without a separate standoff. Control lines adjust that pressure.

• Activation: the brake can be triggered by the kite’s own operation (wind pressure), or controlled by hand or electronically.
• Strut rotation: the strut can be turned to help deploy the brake.
• Spring sail: the sail itself, made of a semi-rigid material, can take both shapes without a standoff.
• Several brakes: figure 2 of the patent shows several brakes spaced along the top surface.

The patent describes the principle on a generic kite, with no mention of quad lines or handles. Reflex is Revolution’s commercial implementation. Public sources add some details about that implementation:

• The Blog du Cerf-Volant (2017) describes a spring fixed to the carbon side spars, which tensions the sail.
• In 2018, Joe Hadzicki wrote that the RX and XX models are built around the spring system, with a “tensioned sail” and reinforced panels (18 June 2018).
• In 2024, the designer described setting the spring perpendicular to the sail, and said the spring position sets how much “Reflex” the sail has and the glide characteristics (19 August 2024).
• A message in the Club 38 group on 16 September 2022 summarises the points of a lesson: set the spring angle relative to the strut (90°), adjust the elastic that tensions it according to the wind, and hand-launch in zero wind (Club 38 group).

These statements come from the designer or from a group member. They describe settings, not measurements.

The designer, who introduces themselves as the inventor of the Revolution, published this demonstration on the Revolution Kites channel on 14 June 2020. The demonstration compares the same kite with and without Reflex, in variable wind of about 0 to 6, on an EXP with 30-foot lines.

1. Stalling. As the sail approaches a stall, Reflex makes it rise instead of falling. Without Reflex, the recovery is poor according to the demonstration.
2. The edge of the window. This is the stressful zone. Without Reflex, the kite drops when pushed toward the edge; with Reflex, it floats down and leaves time to react.
3. Overhead. Without Reflex, the kite falls straight down, and the video says there is no recovery. With Reflex, it comes back and turns to face the wind. The designer calls this “autopilot.”
4. Hand launch. The floating action makes a hand launch easier, especially with 30-foot lines.
5. Reverse. With Reflex, the sail does not flip (wing flip) when flying backwards. Without Reflex, it does.
6. Setting. Reflex can be disengaged in seconds to fly “old school.” The video presents the choice as a matter of style.

• The designer acknowledges that some pilots disengage Reflex for catch and throw, letting the sail fall on purpose to catch it. For a less experienced pilot, the demonstration says that a fall overhead means total loss of control without Reflex.
• The video states that the Reflex design is patented and only available on Revolution kites. It gives no patent number, so the link with US 7,607,615 remains to be confirmed.

• This is a manufacturer demonstration, with one pilot and specific conditions. It explains the function, not the mechanism, and gives no measurement of lift, spring force or wind range.

The comments come from public forums and groups. They are testimony, gathered without a statistical method: they say what was experienced in specific conditions, not how often it happens. Three themes emerge.

Where Reflex wins people over. Several pilots stress stability, especially in unstable winds. Felix Mottram reported in 2016 a “very positive feel down the lines,” even when the kite was lifting almost vertically (Decorators Kites). Mike Klaiber, who flies a Reflex XX with children, notes that the spring keeps the sail slightly pressurised, so the kite floats instead of dropping (Quad Line group). Philippe On Web recommends it to beginners in the EXP version (Quad Line group). On launches, one pilot found that both the Reflex and a copy fly well on very long throw handles in no wind (Revkites thread).

Where it divides. The 1.5 Reflex draws the most detailed criticism. John Barresi, the author of the B-Series, writes that the springs do not seem to do much on a 1.5 platform, and that the 1.5 Reflex spirals to the ground on a 3D catch, with no glide and no “auto-save” of the original Reflex (KiteLife thread). The author nonetheless judges the XX to be the model the technology suits best (Quad Line group).

Other criticisms concern specific uses. One pilot sold their Reflex because it did not suit catch-and-throw (Revkites thread). Paul Plested finds that the floaty catch is no longer possible with the springs, and that axels are easier without them (Club 38 group). Romain Ptikar wonders whether the system takes away part of the pleasure of piloting, that of doing things oneself without artifice (Quad Line group). Marc van der Graaf says they are not very enthusiastic about the system (Revrevoquad group).

Practical friction points. In 2019, Wayne Dowler reported that Reflex rod failures tend to happen around the spring. Some owners reinforced that area; others removed the springs (Quad Line group). A 2017 thread notes that the springs can be bent back or removed, and that some flyers love them while others do not (“No love for the Reflex line?”, KiteLife).

What emerges: the positive views concern the XX, beginners, unstable winds and floating at the edge of the window. The criticisms concern the 1.5 Reflex, catch-and-throw, axels, very light winds and breakage around the spring. Reflex is neither unanimously liked nor rejected: its value depends on the model, the wind and the way you fly.

The designer’s statements, from Joe Hadzicki, are the manufacturer’s. They are not neutral.

A simple observation, with no statistical claim: in the groups and forums consulted, competition pilots and very advanced flyers rarely talk about Reflex as a performance tool. It appears more often as a help for learning, or for flying in difficult conditions.

The designer says so too. In July 2020, the designer wrote that Reflex is “most useful for new pilots who are trying to develop new skills,” and that a seasoned Rev pilot already has the advanced skills for stall recovery (Club 38 group). In August 2020, the designer suggested to a high-level pilot that axels may be easier without the Reflex springs (Club 38 group).

A critic, John Barresi, goes further: in their view, the Reflex “is not a first kite, it’s an add-on” (KiteLife review).

These readings do not necessarily contradict each other. They describe a tool for learning and comfort, less suited to performance. Whether that is a limit or a choice depends on each flyer’s practice.

• Patent Figure 1: the perspective view of the top surface of the sail, with brake 108, spring 110 and its rod 112, fixed to strut 106.
• Diagram 1: the cross-section of the sail, in flying shape (A) then brake shape (B). It simplifies patent Figure 3.
• Patent Figure 4: how the standoff works, in three states: in flight, brake triggered, nose raised.
• Patent Figures 2 and 3: not reproduced here. They show several brakes spaced along the sail (figure 2) and the cross-section of the sail in flight and braking (figure 3), which Diagram 1 simplifies.

• US patent 7,607,615 “Brake for a kite” by Joseph R. Hadzicki
• The first Revolution patent, on this site: read the article
• Blog du Cerf-Volant, “Cerfs-Volants Revolution et gamme Reflex,” 20 June 2017: link
• Revolution Club 38 Facebook group: posts cited above
• KiteLife, Revkites, Decorators Kites and Quad Line threads cited above
• Video “Revolution Reflex? You decide. See how the Reflex adds stability,” Revolution Kites channel, 14 June 2020: YouTube (public transcript used for the key ideas)

The patent on Google Patents: US 7,607,615 B2.