Quinjet

The Quinjet is a VTOL (vertical take-off and landing) aircraft created by Stark Industries and used by S.H.I.E.L.D. and the Avengers for transport and combat.

The Avengers
The Quinjet is an advanced air craft used by S.H.I.E.L.D. and the Avengers for personal transport and aerial combat. It is unknown when they were first created, however, there were several present during Steve Rogers' arrival on the S.H.I.E.L.D. Helicarrier.

In Stuttgart, Steve Rogers, Natasha Romanoff, and several S.H.I.E.L.D. agents arrived in a Quinjet to intercept Loki. Natasha attempted to take Loki out with the Quinjet's forward turret but couldn't target a clear shot. Tony Stark later hijacked the Quinjet's speaker system to play "Shot to Thrill" as he made his entrance and swiftly took Loki out. However, as they were on there way back to the Helicarrier with their prisoner, the Quinjet was intercepted by Thor, who managed to force his way inside and make off with Loki.

Shortly after the attack on the Helicarrier, Captain America, Black Widow, and Hawkeye "hijack" a Quinjet in order to get to New York City and head off Loki and the Chitauri, however, shortly after arriving they are easily shot down by Loki and are forced to make a crash-landing.

Captain America: The Winter Soldier
After the battle of new York, the government granted S.H.I.E.L.D. more funds to invest in homeland security. The Quinjet became more heavily armed than to the previous ones.

Capabilities
The Quinjet is a unique, hybrid-wing aircraft with similar flight capabilities as modern VTOL aircraft and serves as a personnel transport and versatile attack vehicle. The Quinjet is able to reach unknown speeds through two powerful jet engines located at the rear of the ship. It possesses two large, angle-adjustable rotors, one housed in each wing, which grants the ship its vertical take off and landing capabilities. The Quinjet also has adjustable wing tips that can be angled down to intensify the lift of the wing rotors and movement of the ship. This gives the Quinjet unprecedented manoeuvrability as it can make full stops mid-air, hover in place, and make incredibly tight turns that conventional aircraft cannot. The Quinjet also has a variety of weapons, the most prominent of which is a mini Gatling gun style turret mounted on the forward underside of the jet.