Quote:
Originally Posted by flipper35
The Raptor is one that might me reasonably efficient.
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In my opinion, the Raptor has zero chance of meeting its goals.
For those unfamiliar, the Raptor is the brain child of a guy with a computer tech background, who thinks his ideas will revolutionize aviation.
Wide, comfortable cabin, pressurized, air conditioned, supposed to go very fast, very high while sipping diesel fuel.
A 3.0L Audi engine is the base.
Great idea, right? The problem: There has been no actual engineering. The entire project has been done by
"That looks about right".
He has had a couple test pilots flee the program. As problems are found, they have been fixed with Band-Aid type changes, often using methods contrary to long-held aviation standards.
The two biggies:
-The Redrive. Power from the engine to the propeller is transferred through a couple wide rubber belts. Think funny car supercharger belt.
BUT- The engine is on your typical rubber engine mounts, while the prop shaft is rigidly fixed to the airframe. the sprockets and belts are not fixed in relation to each other. Experts have chimed in that this will never last long. During ground testing, several parts have already needed replacement.
-The turbos. due to the high altitudes necessary to achieve the speed/range goals, there are two turbos in series. To do this properly, the thermodynamics must be calculated with precision. With a lower-pressure turbo feeding the second higher-pressure turbo, they must be two different sizes. Both turbos in the Raptor are the same. Another forum discussing this has a long explanation how the Raptor's current turbos will create massive back pressure, overheating the exhaust valves in short order.
Current empty weight is over 1000 pounds more than projected, and very close to the projected gross weight. So instead of five passengers in air-conditioned comfort, just the pilot and a bit of gas, and it's at maximum weight.
That's the result of Band-Aid fixes on top of Band-Aid fixes.
Ailerons were very sloppy. Test pilot could hold the stick all the way to one side, while another guy at the aileron was able to move the aileron through its entire range.
Pulleys in the aileron system were bonded to the belly skin, and the skin was flexing instead of moving the ailerons.
The fix? A steel plate bolted to the belly under the pulleys to stiffen that area up.
Anybody with an aviation background would know to mount control pulleys on solid structure like stringers or bulkheads- Not just belly skin.
And the skin is at least twice as thick as it needs to be. Carbon is light, right?
Between the extra thickness, and adding steel in several places as Band-Aid fixes, the airplane is severely overweight.
Where are we now?
Taxi tests. Lots of taxi tests. Down the runway, picking up speed.
So far he has had it up to 90 knots, and it's still on the runway.
this thing will need long runways, and excessive speeds for take-off and landing.
A few months back, a major rocking motion bounced the airplane enough that it damaged the landing gear. Ailerons were flopping, causing the wings to begin a fluttering motion.
Ailerons not solid, landing gear not able to withstand the equivalent of a rough landing.
The good:
Got to admire the guy's tenacity. So many buy a pre-fab airplane kit, with easy to follow step-by-step instructions, and still do not complete their project.
This guy started with just an idea, and has made it happen. Wow. Congrats.
I just wish he would listen to those that have gone down this road before.
Also- He posts a new video twice a week showing his progress. All the world can see his successes and failures.
But- Whenever somebody with expertise points out a possible deficiency in the comments, he blocks them, instead of listening.
Some say it will never fly.
My prediction? It will fly, poorly. It will never come close to its projected performance, and it will never be a commercial success.
I hope it gets back on the ground, safely, before the turbos roast the engine and the drive belts disintegrate.