Royal Air Force and replacement by the F-35, the RAF Lossiemouth-based 15 (Reserve) Squadron (the Tornado Operational Conversion Unit) was disbanded in March 2017. Lightning: On 23 November 2015 it was announced that a total of 138 F-35Bs will be ordered. 617 (The Dambusters) Squadron officially reformed on 18 April 2018 as an RAF Lightning Squadron. The first four aircraft arrived at RAF Marham on 7 June 2018. The Sentry AEW1, based at RAF Waddington, provides airborne early warning to detect incoming enemy aircraft and to co-ordinate the aerial battlefield. The Sentinel R1 (formally known as ASTOR – Airborne STand-Off Radar) provides a
RAF Benevolent Fund as the "Royal Air Force Memorial Fund" as one of their charitable objects was to raise a memorial to airmen who died in the First World War. The Royal Air Force Memorial was completed in 1923. The monument, in Portland stone surmounted by a gilded eagle, can be seen on Victoria Embankment. Fundraising for the RAF Benevolent Fund occurred outside the UK as well. Prior to the United States entering World War II, Piper Aircraft Company produced 49, one for each state in the US plus another, Piper J-3 aircraft with RAF insignia and nicknamed the Flitfire, to be auctioned