Official Freewing 90mm F-16 V2 EDF Jet Thread

[EDF-Jetpilot]

Oh, and another thing...

I personally think that recommending such nose heavy setups actually curtails pilot development, regardless of whether you want to fly smoothly, or radically aerobatic.

Extreme nose heavy planes are NOT well behaved and constantly fight pilot inputs. This doesn't make pilots learn faster, but rather becomes a drag to their development.

That's not to say that a gyro-run tail heavy setup is ideal for newbie pilots, it's obviously not, but there's a lot of leeway in between. Neutrally balanced or just slightly nose heavy planes are much more beginner friendly than excessively nose heavy models.

Even full scale airplanes offer forward CG limitations just as much as they give rearwards CG ranges. That's not just because, you know... ;)

I completely agree with you and 2Bros, because I also fly all my jets like you, and it's simply much more fun, especially flying fighter jets, since you can easily perform real-world maneuvers, which would otherwise be impossible. However, I think it's crucial that if you prefer a tail-heavy setup, you can correctly adjust the rates, expo, and, most importantly, the gyros, and understand how these factors interact! Most pilots (in my experience) can't properly adjust gyros and have limited experience with them – if you set a gyro incorrectly, your jet will crash, regardless of whether it has a nose-heavy or tail-heavy center of gravity! Beginners and recreational pilots usually don't enjoy flying with a tail-heavy center of gravity. I think xviper is thinking along these lines. But as I said, for me there is nothing better or more beautiful to fly than an F-16 or F-22 with a tail-heavy center of gravity, 70-80% expo with full servo travel on all control surfaces, and a perfectly tuned gyro setting – and that was already the case on my first flights!

[f4u ausie]

Firstly. It's nice to be nice. And. Divide. I've had similar trouble getting good at this one. Don't feel alone don't think U mentioned. R U 6 or8s. Last flight was 10mm back. 8s at1100 grams of 6000 HRB. Does not like slow in the turns. Landing my main concern..
I will get good. If it kills me. Or the plane. Have fun

[Dividebysandwich]

Well I can tell you the combination of the stock elevator neutral position being way too much down, along with the expo, caused me to always be on the steep end of the expo curve. Hence elevator input was extremely twitchy with sub-mm stick travel deciding on whether things were going up or down. This combined with the already sensitive ailerons at 40% expo to an uncontrollable airplane. There wasn't even time to reach for the trim. Putting the elevator neutral at the lower mold line was the most important fix. I can fly the jet at 40% expo but it's a bit sensitive, 65% is a bit too much for me. I'll probably go somewhere in the middle next.

The stock 110mm CG is okay for "scale flying", i.e. not cobra maneuvers, provided there's enough expo - at least for me. I'm sure there's people with finer motor control who can handle 40% expo at a rearward CG with no gyro but that's not me.

The hard landing on the second flight did cause the two wood spars to break and a small crack to form in the foam, but that was easily fixed and reinforced. Last few landings were super smooth, though I'm definitely still cautious with high AOAs.

[Airguardian]

They mostly do for the most part.
And it's kinda rich to see you calling me rude and obnoxious just after speaking of Jon the way you just did.

To each his own, I guess.

And no, it's absolutely NOT irrelevant as demonstrated by Jon and myself along many other people who have succesfully applied the same general lines of fullscale aircraft design criteria to our models setup, substantially improving our models performance in terms of flight envelope, controllability, flight efficiency, etc.

I certainly don't plan on leaving any of the forums I post in, but feel free to ignore my posts, if my words offend you that much.

[xviper]

Real aircraft do NOT always translate well into foamie RC planes, so your statement about us knowing more than those companies is rude, obnoxious and completely IRRELEVANT and pointless. Once again, you've proven to me that there is absolutely no reason for us to have any interaction on any forum. Bye Bye.

[Airguardian]

The previous poster did take my expo suggestion, something you conveniently omitted.

Was it the CG that fixed his issue or the expo setting... ? ;)

Anyway, I find it rather amusing that you brand as 'crazy' what's literally the default modern fighter jet design strategy. Yes, I'm talking about the full scale ones. They aren't made crazy nose heavy, rather tail heavy unstable and computer assisted. Even the older models that are CG-stable in their original conception, use small static margins, not the God-awful nose heavy suggestions we usually see in the foamy EDF market.

So apparently, you and your buddies at the field know better than Boeing, Lockheed, EADS, SAAB, Dassault and Sukhoi combined... come on!

[xviper]

PS: Your depiction of Jon from 2BrosRC is mean, totally out of place and misleading. He does often explain a lot more than what you are implying. He certainly explains a lot more than virtually any other youtube RC pilot by comparison.

Yes, we shall agree to disagree on many things. As for my depiction (I said "IMO") of 2 Bros, I and everyone I fly with (mostly jets) talk about this quite often. We take a lot of what what Jon says and see good sense in it (for what he does and how he flies). However, when it comes to extreme tail heaviness, we all just laugh and exercise extreme caution. We consider this practice to be "crazy" because we don't fly like that.
As for high alpha flight on real jets, that is air show stuff and NOT normal flying. You call it scale. We call it something completely different. We fly in a whole different world. I'm going to leave it at that because to continue would be pointless. I'll leave it up to the reader to use their own reason to believe who they want. And since the previous poster did NOT take your warning about NOT putting the CG back to stock and found greater success, well, I'll leave it at that also.

[Airguardian]

Glad that worked out!
Now, to enjoy the model!

[Dividebysandwich]

Third flight went a lot better. CG is back to stock, gyro dialled up, expo is at 65% at full rates, with less expo at lower rates. Elevator neutral position is around the lower mold line.

The higher expo definitely helped, thanks for the hints!

[Dividebysandwich]

Third flight went a lot better. CG is back to stock, gyro dialled up, expo is at 65% at full rates, with less expo at lower rates. Elevator neutral position is around the lower mold line.

The higher expo definitely helped, thanks for the hints!

[Airguardian]

Oh, and another thing...

I personally think that recommending such nose heavy setups actually curtails pilot development, regardless of whether you want to fly smoothly, or radically aerobatic.

Extreme nose heavy planes are NOT well behaved and constantly fight pilot inputs. This doesn't make pilots learn faster, but rather becomes a drag to their development.

That's not to say that a gyro-run tail heavy setup is ideal for newbie pilots, it's obviously not, but there's a lot of leeway in between. Neutrally balanced or just slightly nose heavy planes are much more beginner friendly than excessively nose heavy models.

Even full scale airplanes offer forward CG limitations just as much as they give rearwards CG ranges. That's not just because, you know... ;)

[Airguardian]

Well, first and foremost, high alpha is SCALE for fighter jets. Even extreme high alpha for some. Many thrust vectored full scale jets can do sustained 70-80° AoA passes, so suggesting that that somehow isn't scale flying is a bit preposterous.

As for book CGs not being dangerous... again, let's agree to disagree, but I almost crashed my F-18 on the maiden flight because stock CG was so terribly nose heavy the model almost drove itself into the ground as soon as I released pitch stick pressure after take-off, and I know for a fact I'm not the only one. That is BAD. Like real bad. And dangerous indeed too. Not to mention these jets will corkscrew to death much easier on turns with those CGs. I had a similar experience with the Gripen and Vulcan. Thankfully I have spared myself the trouble by running much more aft CGs from the get go on other models.

The saying that tail heavy planes fly only once, although false, is a good warning tale to make pilots wary of setting up unstable aircraft, but when people take that as an excuse to set up EXCESSIVELY nose heavy jets, that's the actual disservice to the hobby.

If the manufacturer's CG recommendations were more sensible, I wouldn't have a problem with this. A bit of positive static margin (nose heaviness) is desired for conventional stable flight. But the problem is that more often than not, they are NOT reasonable. When I can move CG 40mm before hitting the neutral point on a 1.5m length model, that's not just a 'wee bit' nose heavy recommendation. That's outright criminal.

And I'll say it again: over the years, I've seen way more crashes due to extreme nose heaviness (especially amongst limited skill pilots) than tail heavy accidents.

PS: Your depiction of Jon from 2BrosRC is mean, totally out of place and misleading. He does often explain a lot more than what you are implying. He certainly explains a lot more than virtually any other youtube RC pilot by comparison.

[xviper]

70%? Jeeze... I usually reduce throw before using that much. I was at 30% on the first flight and went up to 40% on the second one.

Well I'd rather have a CG that's too forward than too far back ;)

About rates and expo. For me, high throws (or rate) demands MORE expo. Lower rate, lower expo. I think of it this way - if I have a large amount of throw, I want more expo to dumb down the first part of the stick travel.

I concur about the CG. If you look at the videos of some of the guys who are using large rearward CG, they are flying a lot of sharp maneuvers and "high alpha". Unless you watch their videos, they don't tell you that's how they fly. I'm near the "book" CG and perhaps a small bit rearward. That's the way I like to fly. I don't do stunts a whole lot and I don't do a lot of slow high alpha stuff. In fact, my planes have difficulty doing hi alpha because I don't set my CG very far back. I'm good with that. High alpha gets old really quick for me. I'd prefer nice, smooth scale sort of flying, with the occasional "stunts", which takes a lot of effort to do even 1/2 decent. I'm OK with that too. I have other planes (jets and prop) that were designed out of the box for doing stunts and 3D stuff. Go take a look at the "2 Brothers" videos. He is one of those "influencers" who flaunt a severe rearward CG. But look at his flying style. He does a lot of stunts and high alpha stuff, even upside down high alpha. He even programs his gyro so he can do these things more easily. He's almost always professing to flyers that book CG is way too far forward, but unless you see him fly or ask him why, he will not tell you why. And in this sense, provides a disservice to the average flyer who just wants to fly their planes and be proficient and make them look good. Not everyone starting new in jets wants to do "aerobatics". And IMO, a stock or forward CG is NOT dangerous. It may inhibit some performance capabilities but NOT dangerous. There are a lot of things in the way you set up the plane that can make it "dangerous". Sticking close to the book CG is NOT one of them. The old adage (although less applicable today due to flying aids and flying styles) is still valid in many cases. "You can fly a plane with a forward CG OK. With a too far back CG, you fly it ONCE."

Now, you should ask yourself -- what sort of flying are you aiming for? Judge what some people tell you, as well as what I'm telling you.

[Airguardian]

70%? Jeeze... I usually reduce throw before using that much. I was at 30% on the first flight and went up to 40% on the second one.

Reducing throws curtails aerobatic capability and safety margins. If you need the throw and don't have it, that can easily cause a disaster that would have otherwise been avoided.

Well I'd rather have a CG that's too forward than too far back ;)

I respect the sentiment, but I do not endorse it. Many people just don't realize how damaging nose heaviness is to flight performance, to the point that it makes flying more dangerous. The stability derived from excessive nose heaviness comes at a heavy price. I've seen more airplanes lost due to excessively nose heavy setups (typically due to nasty stalls on final causing models to lawn dart to their ultimate doom) than from slightly tail heavy ones. ;)

[Dividebysandwich]

When you say "neutral" ELE, do you mean as per this photo:

Yes. That was what I used on the first flight, and reading through posts moving that to 24mm from the top edge is definitely better.

Not being able to get off the ground might indicate you didn't have enough elevator and/or you were flying off grass that was a bit too thick.

Travel and Expo was set as per manual. We have a plastic runway (it's from a big paper machine) so grass was not a factor.

As for "fighting for survival" on the second flight after you moved the CG back 10mm ........... a rearward CG is not for everyone. Those who swear by it, fly in certain ways and have gotten used to handling the plane that way. You might want to resolve the flight characteristics before starting to move the CG back. You might have too high of travel or too low of EXPO or both.

Yeah I'll go back to the stock CG but keep the altered elevator neutral position. As I said both travel and expo are set up as per manual.

Are you even using expo? Lack of expo can usually be the reason for too sensitive pitch control, even on a nose heavy model.
Most of my models run about 70-85% expo on pitch and roll, even after installing a gyro on them.

70%? Jeeze... I usually reduce throw before using that much. I was at 30% on the first flight and went up to 40% on the second one.

Don't go back to stock CG. Too nose heavy. I'm flying like 40mm behind stock (with a gyro, though, ofc).

Well I'd rather have a CG that's too forward than too far back ;)

[Airguardian]

Hi, first post here!
I'm on my second flight on the 90mm v2 and I have to say I'm having issues. First flight was almost impossible to get off the deck - elevator neutral and CG were set to what the manual recommended. So I read up and changed elevator neutral and also nudged back the CG by 10mm. Bad idea, had to fight for survival on the second flight. I did install a gyro before the second flight but had the sensitivity dialed low to avoid oscillations at the first try. Turning on that gyro saved my bacon, but only barely.
So now I'm wondering. Folks here report flying 10mm behind factory CG without a gyro - how?

For the next flight I've dialed up the gyro sensitivity a bit and will go back to stock CG, though I'll definitely keep the new elevator neutral position.

Are you even using expo? Lack of expo can usually be the reason for too sensitive pitch control, even on a nose heavy model.
Most of my models run about 70-85% expo on pitch and roll, even after installing a gyro on them.

Don't go back to stock CG. Too nose heavy. I'm flying like 40mm behind stock (with a gyro, though, ofc).

[Elbee]

Dividebysandwich

Welcome to Hobby Squawk, glad to have you onboard, Sir.

Best, LB

[xviper]

First flight was almost impossible to get off the deck - elevator neutral and CG were set to what the manual recommended. So I read up and changed elevator neutral and also nudged back the CG by 10mm. Bad idea, had to fight for survival on the second flight. I did install a gyro before the second flight but had the sensitivity dialed low to avoid oscillations at the first try. Turning on that gyro saved my bacon, but only barely.
So now I'm wondering. Folks here report flying 10mm behind factory CG without a gyro - how?

For the next flight I've dialed up the gyro sensitivity a bit and will go back to stock CG, though I'll definitely keep the new elevator neutral position.

Re: Gyro ............. Consider putting the gyro on a master gain knob or slider so you can adjust on the fly and not have to change it on the ground for the next flight.
When you say "neutral" ELE, do you mean as per this photo:
This is the starting neutral ELE.
Not being able to get off the ground might indicate you didn't have enough elevator (or set in the wrong place to start with) and/or you were flying off grass that was a bit too thick. As for "fighting for survival" on the second flight after you moved the CG back 10mm ........... a rearward CG is not for everyone. Those who swear by it, fly in certain ways and have gotten used to handling the plane that way. You might want to resolve the flight characteristics before starting to move the CG back. You might have too high of travel or too low of EXPO or both.

[Evan D]

No gyro in mine and balance is an inch behind the marks.

[Dividebysandwich]

Hi, first post here!
I'm on my second flight on the 90mm v2 and I have to say I'm having issues. First flight was almost impossible to get off the deck - elevator neutral and CG were set to what the manual recommended. So I read up and changed elevator neutral and also nudged back the CG by 10mm. Bad idea, had to fight for survival on the second flight. I did install a gyro before the second flight but had the sensitivity dialed low to avoid oscillations at the first try. Turning on that gyro saved my bacon, but only barely.
So now I'm wondering. Folks here report flying 10mm behind factory CG without a gyro - how?

For the next flight I've dialed up the gyro sensitivity a bit and will go back to stock CG, though I'll definitely keep the new elevator neutral position.