Mixing bleed and ram air at a turbine inlet

1. An airplane comprising:

a first medium;

a second medium; and

an air conditioning system comprising:

a first turbine,

a compressor located upstream of the turbine in a flow path of the first medium,

a mixing point at which the first medium mixes with the second medium;

a heat exchanger configured to reject heat from the first medium to a third medium; and

a second heat exchanger configured to reject heat from the second medium to the third medium,

wherein the mixing point is downstream of the compressor and upstream of the turbine,

wherein the mixing point is located downstream of the heat exchanger and the second heat exchanger.

2. The airplane of claim 1 , further comprising:

a third heat exchanger located downstream of the heat exchanger in the flow path of the first medium and located upstream of the mixing point.

3. The airplane of claim 1 , further comprising:

a third heat exchanger located downstream of the second heat exchanger in a flow path of the second medium and located upstream of the mixing point.

4. The airplane of claim 1 , further comprising:

a third heat exchanger downstream of the mixing point.

5. The airplane of claim 4 , further comprising:

a flow of a fourth third medium.

6. The airplane of claim 5 , wherein the fourth medium comprises cabin discharge air.

7. The airplane of claim 5 , further comprising:

a fourth heat exchanger rejecting heat from the first medium to the fourth medium.

8. The airplane of claim 5 , further comprising:

a second turbine configured to receive a flow of the fourth medium and to power the compressor.