Whoever wrote the article is using some very loose language and in at least one place is simply wrong.
The problem is that at a given IAS, the power required is proportional to the TAS; that's why it takes more fuel to indicate 150 kts at 10,000 feet than at 5,000.
This statement is right about the power required, but may be right or wrong about the fuel flow, dpeening on enine type. As I have explained previously, both drag and IAS are related to dynamic pressure (1/2 Rho V squared). (Drag = CD1/2 Rho V squared S) and IAS (is derived from ½ Rho V squared). Every time the ASI senses any given value of dynamic pressure it will produce the same indicated airspeed, regardless of changes in altitude. And provide the values of CD a S (the surface area) do not change, that same dynamic pressure will produce the same value of drag. So the drag at any given Indicated airspeed will not change with changes in altitude.
But As I explained in my first post, Power required is proportional to TAS Cubed. Fuel flow in jet engines is proportional to thrust, and to maintain a constant IAS the thrust must equal the drag. So as Capn Bloggs has said, the fuel flow required to maintain any given IAS will not change with altitude. But in piston engines the fuel flow is proportional to power, so in piston/prop aircraft the fuel flow required to maintain constant IAS will increase with increasing altitude.
Air particles are hitting the airplane with the same force, but in a given period of time, more of them hit it."
This statement can be interpreted in (at least) two ways. If it is taken to mean that the overall force exerted by all of the particles hitting the airplane is constant, then it is true. Because the TAS is higher each particle hits harder, but because of the lower density there are less hits per second. If however the statement is taken to mean that each individual particle exerts the same force, then this is untrue. If I throw a small stone at you at low speed, it will exert a low impact force. If I then throw it at you at a much higher speed it will exert a much greater impact force.
For his example, he says that 20 kias would be enough to make the drone fly. This speed seems easy to achieve. Then he says the problem is the 200 ktas needed, due to the fact that the air is very thin. But hey, these 200 ktas are needed precisely BECAUSE the air is thin, and if the air is that thin, drag must also be very low. So, if drag is so low, why is TAS a problem in the first place ?
Again the problem probably stems from poor wording. While it will not require very much thrust to maintain an IAS of 20 kts, we must first accelerate the drone up to that speed. If we assume that it requires 20 kts IAS to support its own weight, we may well have a problem ensuring that it can accelerate up to this speed with falling to the ground. IAS is just an indication but the real speed required is the 200 kts TAS. We could perhaps use some kind of gun, but this would exert huge acceleration forces, so the drone will need to be very strong to survive the process. This will obviously have weight implications, which would in turn require greater acceleration forces from the gun.
Capn Bloggs
So I do not agree that it will take more fuel to fly (a jet) at 150IAS at 10,000ft than 5000ft. The "power" required might be double (or 3.375 times at FL300) but the thrust/FF certainly isn't.
I suggest that you might wish to read my post again. I did not say that 3.375 times as much fuel would be required. What I actually said was:
Looking at these last two figures, 242 kts is approximately 1.5 times greater than 161, So the power required at 150 KIAS at FL300 will be approximately 1.5 cubed = 3.375 times the power required at 150 KIAS at 5000 feet.
As I have said several times previously in this thread, Fuel flow in a jet engine is proportional to thrust, while fuel flow piston engines is proportional to power.
You do not appear to understand the difference between thrust and power. Thrust is a force, power is a rate of doing work.
Although the throttle levers in many jest are often referred to as the “Power Levers” they do not actually control the power. They control the fuel flow, which in turn influences the thrust. But the propulsive power being produces varies with TAS and altitude. As an example a jet aircraft has its engine running at full power prior to brake release, no propulsive power is being produced. We have lots of thrust, but the TAS is zero. Propulsive power = thrust x TAS which in this case is Lots x zero = zero.
If we now climb to some selected altiude (10000 ft for example), then push the throttles fully open the IAS And TAS will both increase. The increasing TAS will cause the propulsive power (TAS X thrust) to increase. We now have power increasing while our throttle lever angles remain unchanged.