Official Freewing 90mm F-16 V2 EDF Jet Thread

[Airguardian]

I'm thinking more an open framework cam & pin attached to a separated LE.

This is not my original drawing, different author, in theory the principle would be similar.

Linear servo(s) for deployment; could be mixed with "Flap switch, Throttle setting, both???

That wouldn't be scale for a Hornet though. Hornets (as most modern fighter jets), use leading edge flaps, not slats. They don't leave a gap nor extend forward, only droop down. ;)

As for implementation logic, I'd go for the following:

1 - Droop down with flaps. (Easiest)

2 - G-force induced through telemetry. (The higher the Gs, the more droop, on a ramp that went from 1.2Gs to 4Gs, 0 to 100% deflection, for example. This would need fine tuning though).

3 - Alteratively, gyro controlled (unidirectional) so that when there's pitch up rate, the LEFs droop down).

4 - Pitch input linked (Droop down above certain elevator stick input).

5 - Switchable offset (Drooping down on a 2 or 3 position switch like flaps, but without flaps, for things like sustained high alpha).

Ideally you'd only want them to be actuated as a function of AoA, but estimating AoA on a model aircraft isn't trivial, so the options above cover some of the scenarios of interest.

[xviper]

Like all the "firsts" put on modern day RC planes - sequential gear doors, LED lights, quick attach wings, reverse thrust, thrust vectoring, flight controllers, "blue boxes", pre-tuned gyros -- Leading edge slats may be the next "big thing" in model aircraft. A great time to be in this hobby.

[Elbee]

Don’t know if this link will work. It’s from a Facebook video about LE thingie.
https://www.facebook.com/share/r/1D1...ibextid=wwXIfr

xviper Airguardian

Thanks, great vid.

Beautiful design, though a bit more radical than I had in mind.

Flexing the wing skin, WOW.

I'm thinking more an open framework cam & pin attached to a separated LE.

This is not my original drawing, different author, in theory the principle would be similar.

Linear servo(s) for deployment; could be mixed with "Flap switch, Throttle setting, both???

Great vid.

Best, LB

[xviper]

Don’t know if this link will work. It’s from a Facebook video about LE thingie.

https://www.facebook.com/share/r/1D1AwXohFt/?mibextid=wwXIfr

[Elbee]

One did exactly that, just cut the wing's LE and hinged it on the top side. The other didn't cut anything, but made a LE extension that fit on top of the original LE. It hinges on the bottom in a way that when deflected, the top part doesn't leave a gap. This one, you could say extends forward a bit. The good thing about this one is that in the fully up position you know it can't deflect up under heavy loads because it sits tight against the original wing's edge, so it has some extra safety.

Edit: Just a disclaimer, I am talking about the FW F-18 here, not the F-16!

Thanks, AG, both are great ideas.

Best, LB

[Elbee]

Lb. The more complicated... The more interested U r. Luv it

Hah,

Mom always said, "Use your powers for good."

Truthfully, I'd thought about the LE mod when I was building my Hornet, but she was already getting heavy with the cockpit, extra lighting and repaint.

I sketched an LE extension that moved forward and went looking for LE material.

That's as far as I went, so now it's a someday project for another airframe.

Best, LB

[Airguardian]

One did exactly that, just cut the wing's LE and hinged it on the top side. The other didn't cut anything, but made a LE extension that fit on top of the original LE. It hinges on the bottom in a way that when deflected, the top part doesn't leave a gap. This one, you could say extends forward a bit. The good thing about this one is that in the fully up position you know it can't deflect up under heavy loads because it sits tight against the original wing's edge, so it has some extra safety.

Edit: Just a disclaimer, I am talking about the FW F-18 here, not the F-16!

[f4u ausie]

Lb. The more complicated... The more interested U r. Luv it

[Elbee]

Hard to say... they were sent to me privately through Discord and Facebook Messenger, sooo...

I could bug a friend to post his 3DP files somewhere though.

AG,

I could design it, just like to see his methodology.

Did he cut off and reuse the OEM LE? Does it drop downward, slide forward, or a bit of both?, stuff like that.

Always thought an additional 0.5" at the root and a 0.5" at the tips 2" overall in wingspan would help and still not ruin the wing shape.

Fun things to ponder.

Best, LB

[Airguardian]

Airguardian.
Where do suppose I might find a picture of two of said modifications?

Best, LB

Hard to say... they were sent to me privately through Discord and Facebook Messenger, sooo...

I could bug a friend to post his 3DP files somewhere though.

[Airguardian]

Fully agree. Lighter wingload would be great, but working LEFs would work better and make the jet more interesting ;)

[Aros]

The F-18 problems are the result of the lack of working leading edge flaps. LEFs imcrease the usable sustained-high-alpha range and fix the nasty stall that haunts the airframe, as demonstrated by many people already, who modded the jet with working LEFs ;)

IF FW develops a new gen version, I hope it comes with LEFs! That and/or a slightly lighter wing load.

[Elbee]

Airguardian.

Where do suppose I might find a picture of two of said modifications?

Best, LB

[Airguardian]

The F-18 problems are the result of the lack of working leading edge flaps. LEFs increase the usable sustained-high-alpha range and fix the nasty stall that haunts the airframe, as demonstrated by many people already, who modded the jet with working LEFs ;)

[Aros]

I've actually had great success with my 8S version. No gyro, bone stock. I bring mine in much like xviper described in an earlier post. Nose high, manage throttle for altitude, bring her in with brakes. Plops down scale and unceremoniously every time. Even does great fully loaded. Unlike the F-18 which has given me inexplicable problems, this one seems like a sweetheart.

[Airguardian]

A tail-heavy setup run by a gyro is not 'child's play'. It will still be twitchy and sensitive. The gyro makes it usable and the aft CG enables crazy maneuverability, but it's a long shot from being 'child's play' ;)

My F-16's CG is about 35-40mm behind the manufacturer recommendation. The jet is beginning to be actually tail heavy at that spot. If I turn the gyro off, the jet becomes almost unflyable. But this way I can maneuver a lot more agile and do things that a normal setup isn't capable off, no matter how much you program on a tx. ;)

[xviper]

Oh wow. Mine is now 10 mm. Bhind Should I b nervous.. maybe sneek back to25 or just go to it. It has a plus as3x in it

I tend to start mine as close as possible to the published CG and see how it flies. If it flies the way I want it to, I leave it alone. My F-16 is about 10mm back, like yours. I did it because I wanted to be able to more easily get the nose up on final for the landing. This seemed to achieve that so I've left it there. If you like doing high alpha passes as a regular thing, then perhaps going even further back is worth a try but do it a few mm at a time. Even though this doesn't apply in most cases anymore, I'm still haunted by that old saying, "Nose heavy will fly OK. Tail heavy will fly once." Today, we have fancy TXs that can easily give us rates, expo and various mixes that help our planes fly and do things we used to have to do by finger intelligence. Then there are these new fangled gyros that can make many RC models (especially helicopters) operate like "child's play".

[f4u ausie]

Thanku airgardian

[Airguardian]

What xviper said.

Years ago, in the age of sh*tty low-blade-count EDFs, I used to default to high timing to give my birds a bit more oomph.

Nowadays, with the stock 9-12 blade setups most of us run, increasing timing is borderline suicidal. On something like a twin 70mm (Say, Freewing Su-35), going to high timing on modern EDFs can result in 160-180A current peaks if you are using good lipos.
Get ready to smoke them in a heartbeat and get 2-3min flight times if you aren't careful. Of course, your mileage may vary depending on the particular EDF and setup. The most sensible way to experiment with this is by having some measuring equipment or in-flight telemetry so you can quickly work out the effect of your changes before you get a nasty surprise. Most current-modern 12b EDFs I suspect must be running on medium timing by default... maybe low timing in some cases?

[f4u ausie]

Ok thanx