The GrummelNet Jetpack[1] is a gadget in Before the Nexus and Into the Nexus. It is a jetpack upgrade for Clank that allows Ratchet sustained flight after refueling at fuel stations located on various planets.
The GrummelNet Jetpack is very similar in function to the Levitator from Going Commando, although it lasts much longer and allows Ratchet to use weapons while airborne. It was later ported to the 2016 re-imagining of Ratchet & Clank as the XK-81 Jetpack created by Dr. Nefarious, where it is used on planet Gaspar and during specific boss encounters.
History[]
The GrummelNet Jetpack was offered as a prize at the Destructapalooza on Kragg by Thugs-4-Less, who described it as an "oddly specific" prize.[1][2]
In Rift Apart, the GrummelNet Jetpack was mentioned by Clank as one of his installed features.[3]
Gameplay[]
Before the Nexus[]
Ratchet using the jetpack to traverse the Silox pipeline system.
The Jetpack is a fairly expensive gadget, costing 1,312, 2,625, and 5,250 bolts per level. When equipped, it allows Ratchet to temporarily fly over the running lanes, avoiding hazards and enemies. Each upgrade level increases the duration of the flight. Additionally, while airborne, Ratchet can aim to pick up streams of floating bolts.
Into the Nexus[]
The GrummelNet Jetpack is obtained by completing the challenge "Win the Bronze Cup" in the Destructapalooza on Kragg. It is required to progress on Silox for the mission "Power up the Weeblesnog water pumps"; therefore, the player must visit Kragg before attempting to complete Silox.
The jetpack allows Ratchet to fly for a long period by holding 
for as long as there is fuel. Depending on the area, the fuel behaves somewhat differently: in some areas, when Ratchet runs out of fuel, a small amount of fuel will restore on its own, while in others, running out of fuel means the jetpack is unusable until Ratchet finds another fuel pad.
The GrummelNet Jetpack allows Ratchet to traverse wide areas, namely on Silox around the water works, and Thram when searching for gargathon horns. Ratchet can use all his weapons while in flight. Thram specifically has several fights against gargathons with no suitable land for combat nearby.