Official Freewing 90mm F-4 Phantom II Thread

[fieldofdreamsflyer]

Well I have some news that you guys may be interested in. I had a crash today, very unfortunate, although the damage is not bad and that was only plain dumb luck. I was nearing the end of my second flight, flying level at half-throttle just 30 seconds before landing, when I noticed that something wasn't right. At the time I really had no idea what was going on - basically it wasn't responding to pitch and was rising by itself. It didn't want to level when I used a little "down". Before I knew it, the plane appeared to stall and then it acted like a "falling leaf" or like it was in a flat spin... right into trees. but then it pulled out (didn't hit anything) and then did a second flop, and hit the ground pretty much upright. It went into tall brush and damaged the nosecone and cockpit but everything else is OK. If had gone in nose-down then it would have been destroyed, no doubt.

Upon retrieval I discovered that the reason was that the stabilator was completely disconnected from the servo! This happened while I was flying, and I wasn't doing anything particularly violent or high-G, just regular jet maneuvers.

Interesting that it continued flying like this for several hundred feet. I don't know that I could have saved it, even if I knew what was going on. Anyway, I have it on the bench now and I took the rear cover off, this is what I found. I think that this is probably a high-stress connection and I think that a better connection to the servo arm should be considered. Nothing is broken, the pushrod just popped out. I'm posting so you guys can check yours. I think a Z-bend would be a better solution.

Are you sure that didnt hapen when it crashed. If this was a issue , then there would be more jets crashing . Thats a very common set up and has been used for many many years. Another thing I would do is use a piece of fuel tubing on it so it keeps it from popiing off

[DrDeath]

I had planned on doing a Thunderbird with my Phantom, started working on it this weekend. Finished the painting, now it's time for assembly. Thanks to Jeremy Solt for working out the kinks with the decals. Seems we both found the same sheet of decals and we of course went to the best decaler in the country. He picked up his plane first. Now it's my turn.

[RCjetdude]

I went with a z-bend before I ever maidened mine. That is a big surface and nothing against the designers but I did not want to even take a chance on it coming loose. I also went with a tighter ball link and larger diameter pushrod to eliminate as much slop as possible.

[vduniec]

VMFA-531 Gray Ghosts, circa 1980. Decals by Callie Graphics.

[RCjetdude]

VMFA-531 Gray Ghosts, circa 1980. Decals by Callie Graphics.

Beautiful! Love the wet T-shirt..... I mean runway shot! LOL

[TPS]

The Marines have landed. Modified 90mm EDF (JetFan 9B with 2250 HET motor running on a Roaringtop, 5100mah, 6S, 80C battery and CC 200A ESC) gets 3.5 minutes with 35% left. Beats any 8S system out there. Plane weighs 8 lbs and get 7.7 lbs of thrust at 7000' PA. Callie graphics. Weathering is next. Ready to buy 2 more when the gray ones come in!
Phantoms Phorever

[Flash Jorden]

Are you sure that didnt hapen when it crashed. If this was a issue , then there would be more jets crashing . Thats a very common set up and has been used for many many years. Another thing I would do is use a piece of fuel tubing on it so it keeps it from popiing off

Mine was the same way after my crash, but I couldn't tell if it came off before or after the crash. I thought I had lost pitch control before the crash, but I couldn't be 100% sure. I'm going to change mine to a Z-bend now after seeing your post. Better safe than sorry. Maybe some fuel tubing over the rod keeper might help.

[RCjetdude]

The Marines have landed. Modified 90mm EDF (JetFan 9B with 2250 HET motor running on a Roaringtop, 5100mah, 6S, 80C battery and CC 200A ESC) gets 3.5 minutes with 35% left. Beats any 8S system out there. Plane weighs 8 lbs and get 7.7 lbs of thrust at 7000' PA. Callie graphics. Weathering is next. Ready to buy 2 more when the gray ones come in!
Phantoms Phorever

Looks phantastic! That sounds like quite a performer.

[Jmiz914]

Hey flash....same thing happened to me ystrdy on maiden flight, was trimming out and trying to turn to come back when it seemed I had the feeling of no up of down authority either, fortunately I went down on a hudge thicket of briers and landed on belly with barely any damage except for a few scratches from briers. Once back on table, I found the ball link was unattached and servo was not responding,pulled servo,put on servo tester and nothing, servo doesn’t work at all. Like you said, did the link come off in flight? With plane in excellent condition upon retrieval , I can’t see where the pretty soft landing could have caused this nor seem to have no explanation why servo is gone. This is definitely one to watch and investigate. I will definitely be using a better linkage for this servo once I get all redone, I really hope Motion will send me out another servo. I’ve already put in a ticket on this and as always their customer service is impeccable!!! Just very happy my beautiful bird wasn’t totaled due to this problem. Let’s hope we don’t start hearing more about this issue, maby post such as this will make guys more aware so we can nip this before there more unfortunate crashes.

[lomcevac]

Well, I tried to maiden yesterday and was unsuccessful. The grass at our field was a little high and I was unable to get the plane in the air. I will try again next week at a better field.
On another note... where are most people setting the cg? I was wondering if I had mine set to far forward and that may be keeping the plane from rotating. I have it set right at the cg in the manual.

[janmb]

So, finally got my F-4 in the mail, and since I'm a lazy bugger, I'll just ask:

What's the dominating consensus on cg and throws? (no offense to anyone, but I consider pilot experience a far better source than the manual - the latter seems to be more and more off lately)

Based on other recent FW models, I expect the rates too be far too high and the cg to be quite nose heavy.

[TiredIronGRB]

So, finally got my F-4 in the mail, and since I'm a lazy bugger, I'll just ask:

What's the dominating consensus on cg and throws? (no offense to anyone, but I consider pilot experience a far better source than the manual - the latter seems to be more and more off lately)

Based on other recent FW models, I expect the rates too be far too high and the cg to be quite nose heavy.

CG is right on the money but I did tame the rates down a little more.

[TiredIronGRB]

VMFA-531 Gray Ghosts, circa 1980. Decals by Callie Graphics.

Beautiful shot!

[themudduck]

Mine was the same way after my crash, but I couldn't tell if it came off before or after the crash. I thought I had lost pitch control before the crash, but I couldn't be 100% sure. I'm going to change mine to a Z-bend now after seeing your post. Better safe than sorry. Maybe some fuel tubing over the rod keeper might help.

Man those pics in the previous posts are fantastic, awesome work!!

If I hadn't experienced the problem before the crash, I would be suspicious that it happened because of the crash. But I had definitely lost elevator control during flight. It wasn't the ball link, it was the keeper. A piece of tubing as a safety would be good but I am going to install a z-bend just for that extra margin.

JANMB - I only have a half-dozen flights so far. I started with the factory setup and dialed down the aileron a bit and after the maiden I did need a little more "up elevator" mix with the flaps. It flew absolutely beautifully and its very easy to land. I set up the 5000mah Admiral battery to be up against the floor of the front cockpit, which prevents it from going further forward (I did not saw the bottom of the cockpit off as Pilot Ryan suggested) and I thought it flew perfectly. I didn't measure the CG but putting the battery all the way forward will probably make it way nose heavy. I haven't had the opportunity to try moving the battery back. I expect with all the "up elevator" trim this model may, in fact, still be nose heavy. But it sure flies great the way it is.

[t33jetman]

Look at this picture, and think of the G force being applied to that plastic part on every high speed turn.

At least turn the metal 180 degree bend upside down and let the G force be on the metal. Or, you can just go with a Z bend and be done with it.

Are you sure that didnt hapen when it crashed. If this was a issue , then there would be more jets crashing . Thats a very common set up and has been used for many many years. Another thing I would do is use a piece of fuel tubing on it so it keeps it from popiing off

[DCORSAIR]

Well I have some news that you guys may be interested in. I had a crash today, very unfortunate, although the damage is not bad and that was only plain dumb luck. I was nearing the end of my second flight, flying level at half-throttle just 30 seconds before landing, when I noticed that something wasn't right. At the time I really had no idea what was going on - basically it wasn't responding to pitch and was rising by itself. It didn't want to level when I used a little "down". Before I knew it, the plane appeared to stall and then it acted like a "falling leaf" or like it was in a flat spin... right into trees. but then it pulled out (didn't hit anything) and then did a second flop, and hit the ground pretty much upright. It went into tall brush and damaged the nosecone and cockpit but everything else is OK. If had gone in nose-down then it would have been destroyed, no doubt.

Upon retrieval I discovered that the reason was that the stabilator was completely disconnected from the servo! This happened while I was flying, and I wasn't doing anything particularly violent or high-G, just regular jet maneuvers.

Interesting that it continued flying like this for several hundred feet. I don't know that I could have saved it, even if I knew what was going on. Anyway, I have it on the bench now and I took the rear cover off, this is what I found. I think that this is probably a high-stress connection and I think that a better connection to the servo arm should be considered. Nothing is broken, the pushrod just popped out. I'm posting so you guys can check yours. I think a Z-bend would be a better solution.

I flipped mine around so the bent rod is down when the jet is upright, I don't fly it to much inverted and I also put some fuel tubing on the keeper part and where it clips on the rod, so far no issues but it does have mean thinking I will need to change it soon maybe.

[Aros]

I will bring this to Alpha's attention. Definitely something to examine that is for sure. I am going to check mine later today as well. Thank you for bringing it to our attention!

[janmb]

I think a Z-bend would be a better solution.

Thanks for bringing this out there. Definitely needs attention. A Z-bend would clearly be safer, but typically comes at the cost of slightly more slop, since threading the rod will extend the hole by a tiny amount.

Other options might be to use a small bushing with a grub screw for locking the rod in place, or better yet, replace the entire thing with a ball link.


Mudduck and Tired, thanks for the CG inputs. A great test is to see what she does at medium throttle when inverted. Does she require a lot of forward stick?

[Hardway]

DuBro ball links on both ends. 2/56 rod, and new Hitec mg digital servo. :Cool:

[Grossman56]

So my weekend was a wash for flying... rained Saturday and way to windy today... so I airbrushed on my F-4 until the compressor died and then I went to the field to test my out my drag chute lol. I actually got a workout in lol.

Here's an idea!



LOLLOL

Grossman56