Official Freewing 90mm F-104 Starfighter Thread

[Bill]

Rockin' and Rolling.... Hey guys I've been corresponding with Seaviper a bit, and decided to do some testing regarding the ailerons and the Gyro. Really interesting, if you'll bear with me because this is a bit geeky (how in the hell did this post get so long!).

I've been flying the F104 all last season.
I had originally set up my F104 with the pushrods in the outer holes of the aileron horns, and the throw was way too much. Since the model is pretty sensitive to ailerons I reduced the control throw using the radio. I have my radio set to 60% on the ailerons and I have 22mm of throw set. (22mm each way). Its a good flyer at that position.... its still pretty sensitive but I like those fast aileron rolls when I use full aileron! And I fly with about 30% expo to help smooth things out.
I love flying the plane. For all of three minutes at a time LOL

Anyway I haven't found the right setting for the gyro. I started with the dials centered. Its turned down pretty low now. If you look at the tiny dial, the aileron is set between the 9 and 10 o'clock position. I find that when I am coming in for landing, the plane rocks pretty severely even when there isn't much wind. It seems like its too sensitive. Is it moving too much or too little?

Seaviper suggested that he thought the gyro doesn't have any connection to the radio settings. So I did some tests. I turned on the model, waited a minute for the gyro to figure out where it was at. Then I picked up the plane and rocked it from side to side pretty vigorously. The ailerons moved about 3mm (the width of the foam, roughly) each way.

Then I went to the radio and reset the aileron travel to 100% throw. Now I have 32mm of throw! Looks like 45 degrees!
So I would expect to see that the throw would also increase on the gyro.

So I did the same test, and rocked the plane. Well, I found that the gyro moved the ailerons exactly the same amount as before. So its true - the gyro is doing its own thing regardless of the radio setting. - and I agree with Seaviper, there probably is NO exponential in what the gyro is doing as well.

So in other words, if I reduce the throws on the radio, the gyro doesn't care and will keep operating on "full rate".

Of course I can turn the gyro down further, but its already turned down pretty far and you don't get a lot of "fine tuning control" with those tiny pots.

So now I am thinking that I should try changing the pushrod to an inner hole on the servo arm, that will reduce the control throw mechanically.
And the gyro throw will also be reduced mechanically. So for the same gyro setting I will have less throw than before.

If I reset my model this way, I will end up with a higher throw on the radio to get the same 22mm throw on the aileron, and the gyro will also have a reduced throw, giving me greater adjustment potential on the gyro pot.
Another benefit - for a given amount of throw on the servo arm, I'll have less movement on the aileron, which will provide "finer" control.

I won't be able to test it until later this Spring (if it ever stops raining) but I think this is good knowledge to have.
<edit> and this morning I have a foot of snow on the ground.

Thank you, themudduck. This is good work. I too am still futzing with the gyro. The excessive wing rock with gear down has decreased with decreasing the gyro aileron gain. I have it at 9-10 o’clock now. The rock is hardly noticeable. Watching the foamy aerobatic planes with gyros, we all see the wing rocking at higher air speeds if the gyro gain is too high. So, Maybe gradually decreasing the gain is the ticket here. I am still dialing in this bad girl. Let us know how your plan works.

[themudduck]

Thank you, themudduck. This is good work. I too am still futzing with the gyro. The excessive wing rock with gear down has decreased with decreasing the gyro aileron gain. I have it at 9-10 o’clock now. The rock is hardly noticeable. Watching the foamy aerobatic planes with gyros, we all see the wing rocking at higher air speeds if the gyro gain is too high. So, Maybe gradually decreasing the gain is the ticket here. I am still dialing in this bad girl. Let us know how your plan works.

This Spring in NE Ohio, Winter has been like a petulant child that storms out of a room and then comes back, going "OH YEAH - and ANOTHER thing...!!!!" Its raining one day, snowing the next. This morning it was 20 degrees and my car was covered with ice. I am hoping to start flying again soon. They're telling me that April temps are predicted to be below normal all month.

Anyway I have reduced the control throws on my aileron servos mechanically. This should result in the Gyro providing less-sensitive inputs. We will see.

[seaviper]

You have to reach a happy medium with control throw and gyro settings. Reducing one will require increasing the other.

[themudduck]

I know that I am beating a very dead horse but my comments are pretty far back in the thread... so I'd like to mention it one more time. Its kind of a weird thing and I didn't realize what it meant at first.

See, when I had set my model up the ailerons had way too much throw. Which is typical of course, so I reduced it by reducing the throws using my radio - and I added in expo to smooth it out. As we know, this model is very sensitive to ailerons. When I first flew it, it rolled like a drill bit.

So I've been flying it last season and its set just the way that I like it. I like flying scale-like.
But in this configuration, I noticed that the gyro was overcontrolling (making the plane roll back and forth) when dealing with wind gusts and so on. Especially at low speeds, for example during the landing approach.
So I tried turning the gyro pot down. It didn't seem to help much.

So the epiphany was realizing that the gyro is controlling the aileron at 100% rates and with no expo. It doesn't see the radio settings at all!

And with that knowledge in mind, reducing the aileron throws mechanically should help a great deal.
At a given gyro setting... with full mechanical throw the gyro will be sending large inputs to the aileron.
But with reduced mechanical throw, the gyro will send a proportionally smaller input to the aileron.

What this means is that you can set the gyro for a medium setting, giving it more sensitivity to its job, but the aileron response will actually be less due to the lower mechanical throw.

If you DONT do this and just turn the gyro down really low, its not going to be able to do its job properly.

So if the weather ever gets better, I'm looking forward to more flight testing. I'll have increased throws on my radio, the same reduced aileron throw as before due to the corrected pushrod settings, and I am expecting that the Gyro will work a lot better. I have no idea how long it will take to get back out there. So in the meantime I am going to be painting my F4.

[gooniac33]

I know that I am beating a very dead horse but my comments are pretty far back in the thread... so I'd like to mention it one more time. Its kind of a weird thing and I didn't realize what it meant at first.

See, when I had set my model up the ailerons had way too much throw. Which is typical of course, so I reduced it by reducing the throws using my radio - and I added in expo to smooth it out. As we know, this model is very sensitive to ailerons. When I first flew it, it rolled like a drill bit.

So I've been flying it last season and its set just the way that I like it. I like flying scale-like.
But in this configuration, I noticed that the gyro was overcontrolling (making the plane roll back and forth) when dealing with wind gusts and so on. Especially at low speeds, for example during the landing approach.
So I tried turning the gyro pot down. It didn't seem to help much.

So the epiphany was realizing that the gyro is controlling the aileron at 100% rates and with no expo. It doesn't see the radio settings at all!

And with that knowledge in mind, reducing the aileron throws mechanically should help a great deal.
At a given gyro setting... with full mechanical throw the gyro will be sending large inputs to the aileron.
But with reduced mechanical throw, the gyro will send a proportionally smaller input to the aileron.

What this means is that you can set the gyro for a medium setting, giving it more sensitivity to its job, but the aileron response will actually be less due to the lower mechanical throw.

If you DONT do this and just turn the gyro down really low, its not going to be able to do its job properly.

So if the weather ever gets better, I'm looking forward to more flight testing. I'll have increased throws on my radio, the same reduced aileron throw as before due to the corrected pushrod settings, and I am expecting that the Gyro will work a lot better. I have no idea how long it will take to get back out there. So in the meantime I am going to be painting my F4.

That is an excellent point. I can replicate the throw easily if I change where it is located on the horn. But it will help the gyro be more effective. I feel like it is overcompensating and with what you have said it makes perfect sense as to why.Elevator is working perfect with the current gyro setting but aileron and rudder are still jittery... Thanks for the explanation...

[Jhnybgd]

Hey All,I have a spare 8s setup from the f16 ,could the battery location on the 104 support 2 4s 5k batts?
I know it would add weight but im good with that.
I tried to find some build video or still shots of the battery compartment but havent had any luck.

thanks for any info

[crxmanpat]

Although I don't fly mine on 8S, I just stuck two RoaringTop 4S 5800s in mine, and they fit. You should be able to easily get away with two 4S 5000s.

[Jhnybgd]

Awesome,thank you Crx

[crxmanpat]

No problem. Let us know how it works out. I'm currently working on a new scheme for mine (old German Air Force) and may also consider going 8S.

[Jhnybgd]

Im thinking a Vietnam era camo job.
Im on the fence about the yellow version I cant see silver in the air worth a darn.
I like snoopys sniper may do that scheme

[Jhnybgd]

Would like to find a used 1 to practice with if any one has 1 not far from richmond va they want to get rid of?

[gooniac33]

Hey All,I have a spare 8s setup from the f16 ,could the battery location on the 104 support 2 4s 5k batts?
I know it would add weight but im good with that.
I tried to find some build video or still shots of the battery compartment but havent had any luck.

thanks for any info

not sure how you would get this thing to balance with that set up though... the fan is so far back and makes a huge difference with any changes. If you can get it to work it will be awesome!! Just beware of the CG issues.

[Jhnybgd]

I would be using the FW 8s setupwhich the fan and esc are pretty heavy,
so even with the heavier fan it would still be difficult to get the cg back far enough using 2 5000 4s?

[DCORSAIR]

Don't see much action here about the 104, anyone besides gooniac still flying the F-104??

[Hardway]

I do!!!!! When I get the chance!

[mongo]

Im thinking a Vietnam era camo job.
Im on the fence about the yellow version I cant see silver in the air worth a darn.
I like snoopys sniper may do that scheme

i painted my tip tanks red/orange.
helps a LOT...

[Greyhound61]

Pilots, finally maidened my F-104 this weekend. Stock except FMS 90mm EDF, FMS Predator 130A ESC, JP wheel brakes and 2 Nerf Whistles. Was quite nervous but everything went well. My initial adevise, fly it in wide turns and keep speed up especially with flaps deployed. Landing flaps set at about 20 degrees. I am happy to be member of the F-104 family now!

[DenisFerrari]

Just received my F-104 Black/Yellow nice livery! Out of the box quality is just superb! Kept flying my 90mm F-16 all summer (1st Freewing EPO electric jet, tigether with my bigger "jet-A1 propelled" jets and hely's :) ) and I liked it...this is my first 90mm F-104, I look forward to fly her nicely, of course with lot of respect to this marvelous airplane specs and behaviour!Just finished to read all the threads here, very interesting indeed and thak you all.

[Hardway]

Welcome!!! Glad your are on board!!! Good luck with the 104. My 70mm flies nice and lands much slower than you would expect!!!

[DCORSAIR]

I got me another one, sold my first one after a battle with trying to land with no gyro, never hooked it up so I never knew how much the gyro helped this plane, it is so easy to land now, haven't tried it in the wind, heard it can be a handful with the rocking. Maiden flight went great and ten flights total early this morning. Time to put the decals on.