Chris,

You just do not get it. There is no special aerodynamic stuff going on with the design of the Raptor. The fundamentals of Raptor match the Cozy Mark IV on the small side or the Velocity TXL on the larger side. These are well known designs.

To get the kind of L/D you are talking about, you need a high aspect ratio wing. The Raptor does not have such a wing.

As much as I enjoy watching Peter in the videos; his math does not add up. Either on the price, the range, weight, or the "hacks" (for lock of a better description) Peter has done on the plane.

Tim

I would disagree. Raptor is EXACTLY in this class. But I think it is better than either one. And the diesel engine/redivide system is a game changer EXACTLY the way the it was for this guy. But delivers more.

https://www.youtube.com/watch?v=EnmI-9qMFXs

4.2 gallons a hour at 165 knots. And that is one to one prop to crank with a gasoline engine. And not being able to suck the gear up. Stick your arm out the window going 150 mph and tell me what the drag on it is.

I do wish he had a longer runway. When he does decide to lift the mains, I don’t want to see that excessive pitch up he had on one run. At the speed this is going to lift off, it wouldn’t take much float to get him into danger.

Ahmen. Hope he manages that wisely.

You don't seem to have the first clue about powerplants. So I must assume that your understanding of aerodynamics is equally flawed. Or, perhaps it is because the word "polar" is not used in context of internal combustion engines.

If a designer is using drive speed reduction then the rpm of the engine becomes irrelevant. The optimum aircraft engine produces the most power for the lowest weight while driving the propellor slowly. There is a curious type of powerplant called "turboprop" that illustrates this. A diesel engine is the opposite of this in every way. A heavy engine optimized for low rpm torque is exactly what an airplane does not need.

I got a particular chuckle from your understanding of turbos. Got one? check. Job done. hardly. Turbocharger mapping is a science and an art. Turbos are matched to not only the engine but to the engine's application. Diesel engines by their nature require a turbocharger or supercharger to have any reasonable power density. That doesn't mean that they work well at altitude, far from it.

For example, consider a company that builds excavators. The diesel engine powering it is optimized for altitudes where most construction happens, perhaps 0-1500m. If a customer then wanted to use those machines to build a large project in Tibet, the machines would not work very well out of the box. The company might construct a test facility with a combination cold room / altitude chamber and spend millions to redevelop that engine and it's peripherals to function properly in that environment (to pick a not so random example). The resulting engine might have been able to start and make power acceptably but with longevity and fuel consumption not resembling its sea-level fraternal twin.

As for cranking up the power, that is certainly possible, to a point. We used to build 1-off engines as a corporate sponsor for the pikes peak truck race and for european truck racing. Incredible what the engines can be made to do with access to the development resources and a complete disregard for longevity or reliability. But you wouldn't get very far putting that same engine in a kenworth going down I-80.

Turbines have been tried in trucks and trains. They don't work very well.
It's much the same for diesels and planes.

But then, perhaps my understanding of engines is flawed - I've only been working in design and test at the world's largest diesel engine manufacturer for 25 years so i am still very much a student compared to many coworkers. Perhaps you might set me straight using the word "polar" a few times.

The diesels seem to be working fine for Diamond?

You don't seem to have the first clue about powerplants. So I must assume that your understanding of aerodynamics is equally flawed. Or, perhaps it is because the word "polar" is not used in context of internal combustion engines.

If a designer is using drive speed reduction then the rpm of the engine becomes irrelevant. The optimum aircraft engine produces the most power for the lowest weight while driving the propellor slowly. There is a curious type of powerplant called "turboprop" that illustrates this. A diesel engine is the opposite of this in every way. A heavy engine optimized for low rpm torque is exactly what an airplane does not need.

I got a particular chuckle from your understanding of turbos. Got one? check. Job done. hardly. Turbocharger mapping is a science and an art. Turbos are matched to not only the engine but to the engine's application. Diesel engines by their nature require a turbocharger or supercharger to have any reasonable power density. That doesn't mean that they work well at altitude, far from it.

For example, consider a company that builds excavators. The diesel engine powering it is optimized for altitudes where most construction happens, perhaps 0-1500m. If a customer then wanted to use those machines to build a large project in Tibet, the machines would not work very well out of the box. The company might construct a test facility with a combination cold room / altitude chamber and spend millions to redevelop that engine and it's peripherals to function properly in that environment (to pick a not so random example). The resulting engine might have been able to start and make power acceptably but with longevity and fuel consumption not resembling its sea-level fraternal twin.

As for cranking up the power, that is certainly possible, to a point. We used to build 1-off engines as a corporate sponsor for the pikes peak truck race and for european truck racing. Incredible what the engines can be made to do with access to the development resources and a complete disregard for longevity or reliability. But you wouldn't get very far putting that same engine in a kenworth going down I-80.

Turbines have been tried in trucks and trains. They don't work very well.
It's much the same for diesels and planes.

But then, perhaps my understanding of engines is flawed - I've only been working in design and test at the world's largest diesel engine manufacturer for 25 years so i am still very much a student compared to many coworkers. Perhaps you might set me straight using the word "polar" a few times.

A LOT of time and money went into the development of the engines Diamond is using. Yes, their engines and the Raptor’s Audi both use pistons and burn kerosene in a Diesel cycle, but that doesn’t make them interchangeable.

Interesting why we debate an aircraft across 66 pages that will likely never fly or meet its specs if it does.

BTW, my sincere hope is the Raptor flys and meets expectations.

A LOT of time and money went into the development of the engines Diamond is using. Yes, their engines and the Raptor’s Audi both use pistons and burn kerosene in a Diesel cycle, but that doesn’t make them interchangeable.

66 pages and proof is nowhere to be found on this thread. I came to read about the raptor, I stayed for the entertainment.

Ouch. That is just mean

Tim

A couple hundred million later. And the same plane has less performance (UL, speed) due to weight.
However, the diesel versions have a longer range. And after a few hours the diesel engine with its greater efficiency actually can fly farther.

Tim

A LOT of time and money went into the development of the engines Diamond is using. Yes, their engines and the Raptor’s Audi both use pistons and burn kerosene in a Diesel cycle, but that doesn’t make them interchangeable.