Model Aviation X PRIZE. Why isn't There One? Let's Make One

[rcspaceflight]

I was thinking about this again for some reason. What if you forced the air to become a higher speed by funneling it?



I know sonic speed air flow is going to cause issues no matter what, but at least the motor isn't directly feeling those effects by funneling the air. My logic is that you're taking a high speed intake and slowing it down to something the motor could handle, then speeding it back up to the intake speed for the exhaust.

 

[FAI-F1D]

I do my level best to stay out of compressible flow calculations, but something in the back of my mind says that's not the correct procedure.

My personal opinion still remains: trying to do with electric what hasn't even been done with a turbine seems a little backwards from an R&D perspective. It's going to be hard to get sonic flow even with a ducted fan glow unit turned by a Nelson or Jett unit, even with a tuned pipe thrown in.

It is interesting though that because of all the attention it has gotten, the electric R/C record is almost 300 mph, which is considerably faster than the glow record.

 

[rcspaceflight]

It is interesting though that because of all the attention it has gotten, the electric R/C record is almost 300 mph, which is considerably faster than the glow record.

I was thinking that even something close to 500mph would be epic and be beyond the current record. I know that playing around with a static thrust calculator it looks like the max top speed is around 200mph with a prop unless you're willing to let the tip of the prop break the sound barrier. Which of course is fine and possible, but seems like a horrible idea and wasted energy.

I also know that the Concorde slows down it's intake air speed for the engines to work. So there has to be something to that.

Another random note, I guess it's really, really hard to get a car to go beyond 200mph. I think there is an actual club, "The 200 MPH Club", for people with cars (or have driven) over 200mph.

 

[AkimboGlueGuns]

If I may add a #3, fly a plane to the edge of space using only the electric motor. No carry craft. I think that this is the most do able of all of the challenges here, just use an insanely high KV motor at altitude.

 

[FAI-F1D]

I was thinking that even something close to 500mph would be epic and be beyond the current record. I know that playing around with a static thrust calculator it looks like the max top speed is around 200mph with a prop unless you're willing to let the tip of the prop break the sound barrier. Which of course is fine and possible, but seems like a horrible idea and wasted energy.

It's worthy of note that aircraft like Rarebear have exceeded 500 mph by a healthy margin (actually, there was a P-47 prototype in WWII that could exceed 500 mph in level flight at altitude), so that isn't out of the question. Your hardest part is controlling it.

Things requiring consideration:
control surface flutter
control blanking due to compressibility
power density
correct propeller design

None of these is insurmountable, and seeing as how the slope soaring guys have gotten their models to survive 400+ mph, we already have a pattern with which to start.

Visibility will be the biggest issue, and as such, safety becomes a major concern. Somewhere around this point we start making a case for FPV just to be able to control the model.

 

[TTMR]

Space, if I remember my inlet designs right your set up just adds massive drag and doesn't solve the problem. What is needed is a point for the shockwave to form that keeps the intake inside its "shadow" so that the flow seen by the inlet is subsonic.

And so far as blade tip speeds. I have flown over 200MPH with subsonic tips, granted it was full scale but there I had even bigger (>6') diameter props. Each craft that I have done it in used controllable pitch props and that wouldn't be a bad idea here either.

 

[Jnr Kuzi]

Fly around america idea

i feel the Idea of Making a Plane fly accross the United states would be nice.
What if you did this, you make an rc plane like a Bixler/easy star. And then put an APM board in it. Then someone launches the plane to fly to the next city by programing it, when it reaches the next state, another Hobbyist should charge the Batteries & then send the plane to another state and also take a video of it living. By the time all 50 states are done, it should get back to the original owner. Then we can make a compilation video.
If interested, we can start planing.

 

[Snarls]

Maybe we should consider the possibility of a slope soarer to achieve mach speed instead of a prop driven or EDF craft. The current unofficial record speed for a slope soarer is 468mph. I'm not an expert on fluid flow at all, but maybe if the day is windy enough and there was a large enough slope, reaching mach may be possible.