$2\mathrm{.}3$ Low altitude flight on a prototype aircraft at $2000$ m altitude under standard atmospheric conditions

As a result of the experiments carried out at speed U$,$ the power required to pull this plane is a value like P$.$

It has been determined that if the same aircraft is towed at an altitude of $7000$ m in the atmosphere under standard conditions,

$-$ How much speed should be required to ensure dynamic similarity,

$-$ Calculate how much power will be required to pull the plane.

Note: In level flight, the thrust force is equal to the drag of the aircraft, and the power can be obtained by multiplying the drag force by the aircraft speed