YF-19 and SV-51 for radio control

[IAD]

Yeah, basically. Looks even better with wings/canards!

I bought most of the electronics today... A heading-hold gyro, a 4s 2450 mAH 30C LiPoly battery pack, speed controllers, and almost a dozen servos.

~Luke

Edited January 4, 2010 by IAD

[Vepariga]

thats officially the awesomest thing ive seen this year.

[IAD]

Yeah, big deal, this year has just started! J/K

~Luke

[big F]

We all know how this will end. I love your work and cant wait to see the flight videos.

I know its not so important but could you post pics of the electronics etc, Im interested in how things have changed since I last bought RC gear for a plane.

[IAD]

Sure, once I get it... It's shipping from Hong Kong. About 100% cheaper that way, even counting shipping.

Got it coming via EMS, though, so it shouldn't take too long.

~Luke

[SchizophrenicMC]

It must be able to Pugachev's Cobra and land on a moving boat. For that matter, it must be able to Pugachev's Cobra and take off from a boat.

[IAD]

You mean fall off a moving boat backwards, hover, and then climb out vertically, don't you?

Gear arrived yesterday, and the frame is all glued up. Now for the tricky part: sheeting.

~Luke

[IAD]

Got start on the sheeting, and opened a thread over on RC-Groups:

http://www.rcgroups.com/forums/showthread.php?p=14063588

~Luke

[SchizophrenicMC]

You mean fall off a moving boat backwards, hover, and then climb out vertically, don't you?

Gear arrived yesterday, and the frame is all glued up. Now for the tricky part: sheeting.

~Luke

The maneuver is quite similar to the Cobra, thus, I mentioned it for the sake of comic irony. It landed AND took off in much the same, anime magic way.

Best of luck to you.

[IAD]

Post-stall landing isn't that crazy... The landing was similar (in principle) to the tests performed with the X-31, only the variable-incidence wings allowed the FRX to remain relatively level prior to touchdown. The X-31 on the other hand had to fly with a 20+ deg. nose-up attitude, derotating just before touchdown.

The takeoff... Yeah... Never did figure out how they didn't scrape the bottom of the nacelles, as they fell off...

~Luke

[SchizophrenicMC]

Post-stall landing isn't that crazy... The landing was similar (in principle) to the tests performed with the X-31, only the variable-incidence wings allowed the FRX to remain relatively level prior to touchdown. The X-31 on the other hand had to fly with a 20+ deg. nose-up attitude, derotating just before touchdown.

The takeoff... Yeah... Never did figure out how they didn't scrape the bottom of the nacelles, as they fell off...

~Luke

I know poststall landings are possible. I mean, it's the entire point of flaring, really, expanded slightly, to the point of aerodynamic failure. However, my point was the overdramatic way in which the landing, and even more so, the takeoff was accomplished.

My real concern is how could they possibly have throttled up that fast from reverse to 1:1 TW? No turbofan could possibly do that, because of how much time it takes to spool the engines up from idle to anywhere else.

[IAD]

Ok, wait..... Yes, drama, and all, but.... Thrust-reversed turbines do NOT spin in reverse!

Thrust-reversing occurs as fast as the reverser buckets can deploy/retract. Of all the problems with that scene, spool-up times are probably the lowest on the ladder... They could have been running at significant throttle setting with the thrust reverser buckets deployed, and just holding the brakes; given the absurd thrust/weight ratios (vertical acceleration to supersonic from a hover in a matter of seconds), hovering would occur at what, 33% throttle?

~Luke

[SchizophrenicMC]

Ok, wait..... Yes, drama, and all, but.... Thrust-reversed turbines do NOT spin in reverse!

Thrust-reversing occurs as fast as the reverser buckets can deploy/retract. Of all the problems with that scene, spool-up times are probably the lowest on the ladder... They could have been running at significant throttle setting with the thrust reverser buckets deployed, and just holding the brakes; given the absurd thrust/weight ratios (vertical acceleration to supersonic from a hover in a matter of seconds), hovering would occur at what, 33% throttle?

~Luke

I'm not stupid... I'm aspiring to be an aerospace engineer. I know they don't. But, my point is, reverse it barely above idle. You have to spool the engines AND kill the reverse buckets in the fraction of a second it would take for a 50-foot long fighter plane to fall off a carrier and into the icy blue.

Though, far as I recall, you can't throttle too high in reverse, lest you damage the airframe. Plus, TRs don't divert all of the thrust, anyway. Just enough to get your idling plane slowly jammin' backwards. Hell, in a HOTAS cockpit, when a plane has reversers, it's a throttle setting, not a set toggle. Which means you'd be stuck at a preset ~2% and they'd have to throttle instantly to at least 20% with that insane total TW. It's obscene, really. Plus, I don't find turbofans to be very willing to spool up when you're falling backwards. They hardly do in a hard stall. Given, it's a fighter with built-in starters, but still.

[David Hingtgen]

Few airplanes have issues with airframe damage from reverse AFAIK---the KC-135A is one of them, and that's mainly because the original engine is just so utterly insanely loud---it's raw acoustic damage, not buffeting/exhaust battering it. When the sheer noise damages a military-grade frame, you know that's a loud engine... (when an engine is in reverse, that normally bypasses many silencing features, so an engine in reverse at 70% thottle is often louder than at full takeoff) I don't know if I've ever heard anything louder than a DC-9 in full reverse... (and I've heard Harriers hover)

While many planes have a 60kt limitation for reverse (don't use it below that speed, for reasons of re-ingesting their exhaust gases), plenty of planes reverse all the time. See the DC-9 family, 727, and C-17. 757 can too, but it's VERY rare. Main reason the 757 (and other airliners) don't is due to likelihood of sucking up ramp people and baggage carts with their low-mounted engines, more than any engine operation limits. (and terminal/gate noise)

Most airliners can go to a pretty high throttle setting in reverse, but I don't think any hit more than 95%. 70% is on the low end IIRC. 80-90 is probably the majority.

As for speed of reversing---clamshell/buckets are the fastest, then petals, then target, and lastly sleeve.

I think the main issue is one schizo mentioned---reversers simply aren't that effective. Many are as low as 10% of the equivalent forward-thrust rating. So you might need a 10:1 thrust ratio just to make it work at all, much less have good acceleration.

[anime52k8]

I think we're all missing the most important issue. And that is, will it be able to reverse the orientation of it's wings while doing a nose down flip?

[IAD]

Nope, variable-incidence wings got cut from this build... Issues with the forward-swept wings and actuator loads. (And airfoils, and weight, and space, and.........) Still hoping to do the flip.

Regarding reversers, I rest my case. (Thanks for the info David.) If an airliner can use high throttle in reverse, I'm SURE the FRX can. Speculation on the interface (slaved reversers on the HOTAS, etc.) is irrelevant, since whatever it was, it allowed the throttle setting to stay constant while the reversers were actuated. Just chalk it up to software/FBW magic. Maybe something like in YS Flight.

The point is, for a work of fiction, there are bigger issues with that scene than something as mundane as retracting the thrust reversers.

More on-topic: I've gone through a few different iterations of retracting landing gear... Even though it's not exactly accurate, I've returned to a canted-axis (SU-27 style) design. I built a two-axis unit, but to get the wheels into the bays (without hitting anything) was insanely difficult, whereas the canted axis swings both up and towards the centerline, making it much more suitable.

I'll post pictures shortly.

~Luke