Forces News has been told that the upgrade programme for the Typhoon fighter jet is “on time and on budget".
New missiles have been added including laser-guided Brimstone missiles.
The aircraft need to be ready by the end of the year in time to replace the Tornados which are due to go out of service.
The Typhoons are the RAF's frontline jets, which have been used in missions over Iraq and Syria.
Currently, the fighter jets are being enhanced to attack targets on the ground with Brimstone missiles.
Test flights are being carried out on a daily basis at Warton airfield where the new capabilities are being added.
Chief test pilot, Steve Formoso says the Brimstone is a "small precise missile with a laser-seeking head."
"We can target individual vehicles, individual tanks and even just the tank turret in a very discrete small area."
The upgrade also includes air to air meteor missiles which allow pilots to fire on targets that are beyond their visual range.
Air to surface storm shadow missiles with a deep strike capability has also been added.
The upgrades are to make sure Typhoon fighter jets can replace Tornados and carry out more roles.
Mr Formoso added:
"A Typhoon will do the bombing role but it's also capable of being used in the air to air environment, so shooting other aircrafts down or doing quick reaction alert."
Andy Flynn is in charge of the project and says they are "on time and on budget."
"It's been going on since 2013 and everyday has counted - we are on plan to meet the chief of staff's milestone of Typhoons taking on all the capabilities of the Tornado."
"You see a mixed fleet of Typhoon and the F35 working really closely together and they will have their own specialties and different missions they will have to perform."
"From an industry perspective, we're just ensuring that the RAF gets the best available capabilities that allow them to have a choice and to give the Command the choice to be able to go out and perform all the missions it needs to do."
Test trials are being carried out to ensure the capabilities of the Typhoons are met.
It's not just the new weapons but the systems that control them are also changing.
The chief test pilot said the new system allows him to have more control over the aircraft.
"The fly control system allows me to do absolutely anything I want with the aircraft - so it's always giving me the maximum amount of performance without me having to worry about limits on the aircraft itself."
"I can get myself into a position where I can shoot down another aircraft a lot quicker."
The plan is to get all of the Typhoon fighter jets ready by the end of the year.