I was never a good officer about reading the manual rather than asking a sergeant and I didn't monitor engine instruments a lot, but the aircraft and I both felt the percentage of engine thrust lost to density altitude. Ten to forty percent comes to mind. It seemed to take all of the remaining sixty percent or so of engine thrust just to stay level in stable air. This excess engine thrust for climb, or lack thereof, was also ball park. I expect the lack of stable air during the heat of day made this hard to figure accurately anyway.

I didn't know of any calculations for natural energy so I used ball park percentages there also. Heat produces this energy so the hotter it gets, in the case of thermals, the more of it. Wind energy can be cold, but my understanding is that heat started the ball rolling. Or does cold suck the way heat pushes? So with downdrafts seeming to equal updrafts and headwinds seeming to equal tailwinds in strength and frequency, a ballpark energy percentage would be zero. If we manage this energy, however, we can achieve larger percentage gain than possible with installing a larger engine. We can fly fast through downdrafts and slow to stay in updrafts longer. We can select altitudes that will mitigate the headwind reduction in ground speed or increase the tailwind boost to ground speed. And we can use ridge or hydraulic lift from wind over uneven terrain. Using rate of climb as the scale, the percentage of extra lift resulting from natural energy management can be impressive when compared to the percentage of extra lift resulting from excess engine thrust for climb.

The down side of all this free natural energy is turbulence. Like MTV's visual illustration of water moving swiftly over rocks in a stream, orographic lift can be turbulent. Like EZflap's visual illustration of the shaft of wet downdraft air inside a ring of rising air in an air mass thunderstorm, transitioning rapidly from a mass of rapidly descending air to a mass of rapidly rising air, or vis versa, can be turbulent. Thus, the maximum management of natural energy in the heat of the day can produce percentages in the hundreds rather than in the tens. But it not the pleasant flight most suitable for family travel.