In theory if we knew the dragon's wing area, coefficient of lift, coefficient of drag, and dragon's maximum flight speed, we could determine their thrust. However we don't know your dragon's max flight speed, Cl, or Cd.
In level flight Lift = Weight and Lift/Drag = Weight/Thrust. If we know the lift drag and weight we could then easily determine thrust. Determining lift and drag is non-trivial. Given the many unknown quantities deriving thrust this way is a bit of a dead end.
For completeness:
The equation for lift is L = (1/2) * d * v^2 * s * Cl where: * L is lift * d is the density of the air * v is the velocity * s is the area of the wing * Cl is the coefficient of lift
The equation for Drag is D = (1/2) * d * v^2 * Cd * A where: * D is drag * d is the density of the air * v is the velocity * Cd is the coefficient of drag * A is the reference area
However if we assume that your dragon can hover we can derive some numbers that don't rely on as many undefined quantities. 229
Unlike level flight where aerodynamic lift counteracts the force of gravity, downward thrust needs to counteract gravity on it's own. This greatly simplifies the equations.
For a 2700 pound (1225 kg) dragon to hover it needs overcome the force of gravity, without the help of aerodynamic lift. At a minimum it will need to be able to produce at least 2700 pounds of force (about 12000 Newtons). Add an extra 25% to that to give your dragon some ability to climb and you're looking at a total thrust of 15000 N. Given that in level flight migratory birds like geese have thrust to weight ratios as low as 0.05 having a TWR of 1.25 should make your dragon a quite capable and aerobatic flyer.
To put that thrust in perspective that's slightly less thrust than the Messerschmitt Me 262's two engines combined. While your dragons still put out a lot of thrust, unlike a jet engine where the thrust is concentrated in one location, that power is going to be dispersed over the full area of the 50ft (15m) wingspan.
Getting caught in the downwash of your dragon's wings is going to be noticeable but isn't going to do any structural damage. 160