RC fighter model UAV build in Jet engine 360+mph [video]
youtube.com
youtube.com
I wonder how this thing handles loosing contact with the controller?
It's no wonder the FCC in US is getting less and less RC friendly, besides the typical "home land security" drama stuff like this in a public park could be a real problem from noise pollution to safety of other people in the area.
All this said, must be quite a rush to play with something like that, I would love to fly it in an open field deep in the desert with a clear open sky.
Reading the very nice detailed instruction manual[1]:
To the avoid hearing damage, always use hearing protection when
you are near a running turbine engine!
Along with a couple warnings: A flying model with a turbine can reach higher flight speeds
than ducted fan-powered models, because the turbine’s thrust
degrades less with higher flight speeds. With attainable flight
speeds of over 250 MPH, you can quickly run out if flying room.
There is also a danger of developing control surface flutter
or mechanical overload, causing the model to fail in flight.
That said with a list price of $4,195.00 just for the engine I have to imagine it'll be a while before we see 100's of these in the air at random parks.[1] http://www.jetcatusa.com/PDFFiles/Instruction%20manual%20V6....
> In the U.S.A. the FAA heavily regulates flying of such aircraft to only approved AMA Academy of Model Aeronautics sites, in where certified turbine pilots may fly. Also, the AMA requires model aviation enthusiasts who wish to operate miniature gas turbine powered RC model aircraft, to be certified in the operation of the type of gas turbine engine, and all aspects of safety in operating such a turbine-powered model aircraft, that they need to know in flying their model.
https://en.wikipedia.org/wiki/Radio-controlled_aircraft#Jets
Either it's a rip off or somehow "Jukin Media" got the rights to it... It never ceases to amaze me when old stuff goes viral like this. Maybe it's the keywords stuffed in the title, 'cause UAVs are a pretty hot topic these days, but this thing is not a UAV.
http://www.jetcatusa.com/p160.html
Executive summary appears to be: 36 lbs of thrust with a (dry?) weight of 3.1 lbs and a fuel consumption of about a pound per minute. Sounds shockingly good, so I have to wonder if the compressor is basically an ablative heat shield and this is good for only a few runs.
That said: doing this stunt in what looks like a suburban park strikes me as shockingly irresponsible. This thing can easily kill someone, wreck a vehicle or puncture a roof if control is lost...
I'd be more concerned with drunk or texting drivers than a R/C jet engine killing me.
I assume that one does not simply dive into the RC world with a jet turbine. Instead this individual has probably had a lot of practice with slower planes, does not want to injury anyone, and is not doing this in Central Park NY
I have no doubt the pilot is experienced, and that the area in general is clear.
He does have to make sure he flies safely, but that's his concern. Relax and enjoy the show. :-)
Note that I didn't agree with the claim that this specific flight was irresponsible, just that the fact that more people might die from drink driving is basically irrelevant.
So no, the burden of proof is not on me.
Someone shows a video of a RC jet flying extremely fast and the assumption is this guy is endangering the public and has no regard for safety of others.
Lets just get congress to waste time implementing laws for both fast flying RC planes and another one to make it illegal for your tiger to eat a person.
Except you have no reason to think it was in a 'suburban park' other than for the reason you get to judge someone you don't know.
The footage clearly looks like a huge open field with no other people visible or vehicles or roofs around.
Maintenance interval: 25 hours
Pretty amazing and I'd love to see the insides of this engine.
What makes you think that someone who can:
1: Build this plane
2: Demonstrably fly it very well, with clearly a significant amount of experience in flying RC planes, and probably other high speed RC planes
will overlook all safety precautions and take what is likely the highest powered plane they've flown, where something is comparatively likely to go wrong vs traditional RC planes, and go fly it in their local park with people/houses/etc. around?
I'm shocked at the nerve I seem to have hit here. I'm not trying to take your model rockets away here, but this is not a harmless device. I think many people here lack an intuition of how fast "360 mph" is or the kind of energies that are involved. This is getting into the speeds seen for muzzel velocities of handguns, and that engine weight a hell of a lot more than a bullet.
Dangers like that require more care than just "it looks safe to me". Where are the people guarding the range and warning off intruders? Where is the posted notification of the testing schedule?
edit - this looks like there is the edge of an airfield on the other side of some pylons. If it is near an active airfield, or if there is any controlled airspace in the vicinity, then I would be incredibly surprised if air traffic control was not kept informed as per the existing regulations.
You're preaching to the choir. The hobbyists in the video are probably more aware of that than anyone in this thread.
Second, you don't know that they don't have permission to do stuff at the airport for say an hour because its posted. Your whole argument amounts to fear uncertainty and danger.
> I'm not trying to take your model rockets away here...
But you'll spout off on an unrelated forum about dangers you don't even know are mitigated? Not to be too blunt, but grow up. These are professional rc modelers. They know the dangers better than you do. You don't design a launch system for a jet turbine rc model without keeping safety in mind.
No, actually; the average bullet travels at 2,500 feet per second (around 1,700 mph) [1].
Also, the pilot of a member of the Jets of Norway R/C club. These are probably some of the most experienced r/c jet pilots in the world. I'm sure they understand the risks involved better than any of us in this thread.
[1] http://www.mythbusterstheexhibition.com/science-content/dodg...
edit - Boxer Rocky Marciano's punch was measured at 1028 joules, which is supposedly a greater kinetic energy than an armour piercing bullet. Direct kinetic energy comparisons are not as useful as you might think.
If not, then don't insult someone that appears to be extremely competent with years of experience, and call them irresponsible because you're jumping to conclusions.
And I did in fact witness a jet-powered RC plane being flown there one weekend, which was quite impressive. At no time was a real airplane in danger of some kind of collision.
The point is, RC clubs like this one do think about this stuff, and they do take appropriate precautions.
It look like an R/C air park, actually. I live near the headquarters for two large hobby companies (Hobbico - makers of RealFlight, mentioned elsewhere, and Horizon Hobbies). One of the two (I don't remember which) built a similar air park specifically to provide a location for flying R/C jets.
The R/C club is out flying jets most warm weekend days. See it here: https://www.google.com/maps/@40.0591456,-88.5519564,366m/dat...
http://mvc-apollo68.nl/ https://goo.gl/maps/hYYQg
That's somewhat uninhabited for The Netherlands.
The compressor isn't the part of the engine which gets really hot here; that would be the turbine. In these kinds of engines the turbine is typically made out of Inconel, which has no problems handling the ~800C exhaust gas temperature seen at maximum thrust. Preventing the EGT from exceeding a specified limit is the main job of the engine computer, so this is not a common failure mode.
The service interval on Jetcat turbines is 25 hours (some manufacturers specify 50-hour intervals, or even longer), for which the significant portion the work involved is a bearing replacement.
While the thrust-to-weight ratio does seem very good, keep in mind that the quoted weight of 3.1 lbs is likely to not include ancillaries (engine computer, battery and mounting hardware). Also, lubrication is provided by oil mixed in with the fuel rather than a closed-loop oiling system.
A thrust-to-weight ratio of 10:1 is impressive, but not out of line with what you'd expect to see from a full-sized turbojet. On the other hand, the thrust-specific fuel consumption for these engines is much worse than a full-sized engine due to the much lower pressure ratio.
Also, the shot at 4:08 appears to show the runway. The shot at the end where it's landing clearly shows a boundary between longer grass and shorter grass meant for belly landings. We had all of these things at our flying field.
Given the equipment setup, launcher, gauges, fire extinguisher, etc., I'm going with the probability we're dealing with a couple of pros who are capable of conducting this flight in a safe manner at a designated location. You jumping in here making guesses about intent and outcome is a bit shortsighted, and the FUD you are hypothesizing with is simply there to elevate interest in your comment.
Y'know, there was a time on HN where making a supposition like that would be met with... an assumption that it was delivered out of genuine concern and not an attempt at "FUD" to "elevate interest" in the comment. Fuck you, basically.
This whole thread makes me sad. Your post is the most informative and valuable, and it's still just ad hominem flaming nonsense.
This site used to be better.
I'm sorry this mad you sad. That was not my intent.
As an aerospace engineer, this is cringeworthy. How exactly would this compressor function as a heat shield? Is it experiencing hypersonic intake flow as part of an atmospheric reentry vehicle? Makes no sense.
Could weight be saved in a jet engine by making parts of it ablative? I should think this would play havoc with clearances, so it would only be applicable to parts where the exact dimensions aren't too critical, which I suspect would preclude everything near the compressor and turbine.
Also, ablative heat shielding wouldn't apply to anything not exposed to high heat, so this would only apply to the combustion chamber and everything downstream of that.
EDIT: This makes me curious about the pressures in jet engines. They range from ~pi for early WWII engines (Junkers Jumo 004) to almost 40:1 for modern ones! According to pv=nrt, modern jet engine compressors can get pretty hot, apparently. (Disclaimer, I am not an engineer!)
That said, its an amazing to me this guy can keep his head 'in the plane' which is to say at that speed can fly the plane to its orientation rather than his own. When I've flown model planes there are always times where I'm turning the wrong way because I've mixed up the front back / left right controls given a particular plane attitude and direction. (and yes crashed a couple which made me feel horrible and so I stick to vehicles :-)
Next up I hope someone can build a FPOV version so they can fly it from the "cockpit". That would also make for a great video.
If you think the orientation skills in this video are impressive, you should check out the professional 3D RC helicopter pilots!
https://www.youtube.com/watch?v=KuDptulCpK0#t=37
pretty impressive toys. How do you control this thing without FPV?
http://www.rcgroups.com/forums/showthread.php?t=1609281
With a big hill, the right wind, and an appropriate unpowered glider, it looks like this: https://www.youtube.com/watch?v=KjASRmgQWoo
Dont get me wrong, I've tried flying normal RC planes, and Im rubbish at it, it is still hard and skillfull. But, if you spend some time on YouTube looking at what people can do with these things, you'll end up wondering if they are bending physics.
10 hours on the sim using a high-wing trainer with lots of dihedral[2], learned how to land in a gusty cross wind, then out in to the park with my high-wing high-dihedral trainer. Took off, flew, and landed no problems - the RealFlight trainer was nearly spot on.
I then bought a model F4U Corsair, much different plane to fly, they go where you point them and don't self right or self level like a high-wing high-dihedral aircraft. More RealFlight training and then flew and landed it successfully first go to.
Lots of fun! The parks I had easy access to weren't in suburbia though.
1. http://www.realflight.com/ 2. http://en.wikipedia.org/wiki/Dihedral_(aeronautics)
Not quite as fast, but just as much fun!
Also, it's worth pointing out that it's not a model of a fighter jet, and that this video seems to be a repost of one that's been up for five years: https://www.youtube.com/watch?v=dTHWBSluUjU
Could something that small break the sound barrier?
Why not? Missiles and rockets of similar size do.
Also, the Reynolds number will be completely different for a model aircraft compared to a full-sized aircraft, so they will behave quite differently aerodynamically.
It's also worth pointing out that even the fastest full-size jet aircraft can only just break the sound barrier at sea level (the F-111 did Mach 1.2 at sea level) – going supersonic typically requires flying at a high altitude, which obviously isn't practical or legal for a radio-controlled model aircraft.
For low speeds, maybe. For high speeds, you're well into the high Reynolds number turbulent regime. I've worked on R/C aircraft designs and I'm reasonably sure we got decent results with inviscid aerodynamics. At sea level, you're going to see Re in the millions.
Regarding the Square-Cube law, I'm not sure it's that relevant here. It's pretty clear you could put two of those engines in a AMA sized model, so not exceeding 55 lbf. That'd give you a thrust-to-weight ratio of greater than 1.0.
Yes, a small turbine-powered RC aircraft can easily have a higher thrust-to-weight ratio than a full-sized aircraft, but it's not thrust-to-weight ratio that determines top speed; it's thrust-to-drag ratio.
This is where the square-cube law comes into it. If we take a full-sized delta-winged high performance aircraft like the Eurofighter Typhoon, we could very roughly approximate the difference in drag between that and the model to be proportional to the difference between the square of their wingspans.
I'm guessing the aircraft in the video has a wingspan of 1 m, and the Typhoon has a wingspan of 11 m, so the drag should be greater by something like a factor of 121.
However, the Typhoon's engines provide a combined 180 kN of thrust, which is greater than the 160 N thrust of the Jetcat P160 by a factor of 1125.
So, you can see that the thrust-to-drag ratio of a full-sized jet fighter is something like an order of magnitude larger than for a model aircraft like this, which is the main reason why model aircraft are unable to attain supersonic speeds.
Of course, supersonic flight for model aircraft would pose all the same problems it poses for full-sized aircraft; onset of compressibility affecting control surface response, engine inlet geometry and so on.
And parasitic drag dominates, right? Ok, so yeah, I was thinking in terms of induced drag. Thanks for the discussion. I enjoyed it and it was a good refresher.
http://en.wikipedia.org/wiki/Radio-controlled_aircraft#Jets
> In the U.S.A. the FAA heavily regulates flying of such aircraft to only approved AMA Academy of Model Aeronautics sites, in where certified turbine pilots may fly. Also, the AMA requires model aviation enthusiasts who wish to operate miniature gas turbine powered RC model aircraft, to be certified in the operation of the type of gas turbine engine, and all aspects of safety in operating such a turbine-powered model aircraft, that they need to know in flying their model.
I still wonder what are the best tech available to have a camera/screen on this thing, with what latency.
I'm guessing that's at least partly for cost reasons, but mainly because you don't even need to ask the "what latency" question. Even though iPads/cellphones/OcculusRift have much better and higher resolution screens than most of the inexpensive hobby FPV gear around, the lag as you digitise/compress/decode real time video streams is both too long and too variable.
Remember John Carmak's rant about being able to get packets to London quicker than he can get them onto his screen? Imagine trying to control a ~400mph toy plane when you aren't sure if you've got 15 or 200ms of latency at any time? That'd represent "seeing where you are" something between ~10 and 200 feet behind where the plane is right now.
good careers to be had here.