RCFlyerDan

My Feedback: (54)

I bought my F-4 used. I thought that I would share pictures to give ideas. I gutted it, then refurbished. The original installation had the SM pipe with the end pointing down. I bought a straight TAMS pipe.


This was the engine installation by the previous builder. He raised the engine and the SM pipe with the bend pointing down.

He raised the bell mount. Notice the rails mounting to the bulkhead. You will see pictures of my installation of how I lowered the rails on the bulkhead.

He raised the engine mount.

RCFlyerDan

My Feedback: (54)

Here is how I modified the installation.


Here, I was adjusting the angle of the new rails. I was still in the mindset of using SM pipe. Notice the bulkhead mount is being cut away.

The bell hadn’t been mounted, just fitting

This is the down angle. I had to adjust the nozzle mounts at the back.

I have lowered the rails on the bulkhead. This is the TAMS pipe.

Finished installation

Erik R

My Feedback: (32)

Maidened my, new to me, phantom. Bought it used, but with a good pedigree. Flew awesomely with a Swiwin 190. Has a Tam pipe, angled down. I didn’t listen to all of you about the main gear mounts. Landing was firm, not hard, and one of the mains ripped out. It’s repaired, and I’m going back out to terrorize the field tomorrow. Great jet! Thanks for all the good info.

Erik R

My Feedback: (32)

Video by Ed Martino.

luv2flyrc

My Feedback: (6)

Very nice! Have never flown mine off of grass. How long is that grass strip?

Mike

Erik R

My Feedback: (32)

1000ft. It takes off in less than half with the 190 power. If I make a short approach, it will land in about half also.

RCFlyerDan

My Feedback: (54)

Hey Guys!

I flew my F4 this weekend at a Warbird event. I’m still in the process of trimming my F4 with about 20 flights on it. I have learned some things that I thought that I would share. I use soft field TO technique, which normally gives a smooth rotation on any jet. I’ve been trying to solve the aggressive rotation at lift off. I thought it was a balance issue, and now have it tail heavy. I started where Kevin recommended at 345mm, but now behind it. I don’t know where, because I adjust by flight balance and performance. You will see this on the TO where I actually give it down on TO. I have 3 tanks full and about 50oz of smoke oil over front center tank. Another indication is the wing walking down final. I have figured out that some of the issue was negative AOA sitting on the ground. I flew a buddy’s 1/6th Twin F4 with the nose gear extension for positive AOA. Its rotation is smooth and scale.
I added air to mine and it has helped. I haven’t moved my battery back forward a bit yet. The 1/6th is so much easier to fly. I even landed it on one engine, size 166. Although it barely held level flight at full throttle with the gear down. I landed it no flaps. But, back to this size.


Winds were about 10mph down the runway.

Take-off 1


TO 2


Landing

aaronforth

Was going to post this after our Jet rally but i forgot 😅.
location is the Tofield Airport in Tofield, Alberta




Its in the shop now getting some upgrades to the nose strut 😎

Would love to get the operating canpoy working, but its second hand and not the best shape 🥴

kwik

RCFlyerDan;
Here is one of my takeoff's. 320mm.

RCFlyerDan

My Feedback: (54)

Nice maiden and soft field take off. Putting air in my nose gear increasing the AOA helped. I just had another thought that I have too much down thrust angle on the pipe. That would also cause an aggressive rotation if too much downward thrust. At least I don’t care for how fast mine rotates on its own. It’s not scale. Each take off, I hold less up too.

kwik

I had to invert my pipe, so that it points 5 deg down at the exit. This to avoid the elevators to be heated up by the exhaust.

I never dared to do as the full scale F4's do; Full elevator at standstill, and then full thrust. I have far too much respect for this plane.

RCFlyerDan

My Feedback: (54)

I’m using a TAMS straight bifabricated pipe. Because I had to fix the stab puff from the previous owner, I went for the most down thrust that I could get to avoid puffing the stab again. I didn’t think that extra down thrust would create an issue until today trying to troubleshoot it.

aaronforth

What issues are you having with the down thrust ?

I have the Tams pipe and around 4.5 degrees down and not seeing any issues in 4 seasons now

RCFlyerDan

My Feedback: (54)

The aggressive rotation at TO.

aaronforth

Thats odd I dont have that issue. Maybe you have more then 4.5 degrees. Different CG ? Mine is set at 325-330

kwik

I replaced the air-valve in the nose-leg with a nipple for a 3mm air-tube, and connected it to the brake-systems air bottle.

So, just before takeoff, I fill up the air-bottle for the brakes with 100 PSI.

The nose leg then straightens completely out to full length.

Sometimes I have to refill some silicone-oil too. I use DOT 5 brake fluid; Its silicone oil.

aaronforth

I am replacing the stock nose strut with the air extension matrix stut that David mentioned earlier. More so for scale effect as my Takeoffs are good. I do fly off of pavement so maybe thats the difference.

RCFlyerDan

My Feedback: (54)

I mentioned in my post #482 that I started with Kevin’s recommendation of 345. I like a neutral flying plane/jet. I am trying to solve the aggressive rotation, because it isn’t scale for competition. I felt that at 345 it was still nose heavy for me, and moved a Jeti 2S LiIo
back about 22”, and flew the jet. Videos above. I know now that I am definitely tail heavy and still have too aggressive of a rotation for scale. I probably do have more than 5 degrees, as I mentioned.



I can just move the epoxy sticks to adjust the angle.

Erik R

My Feedback: (32)

Dan, the down thrust pushes the tail up, and causes a pitch nose down, with an increase in power. If you decrease the down thrust, it will only exacerbate the problem you are experiencing.

I also have the straight Tam pipe, angled down quite a bit, and experience pitch trim changes in mine, with a change in throttle. My BVM F-4, and my x-treme jets one did the same thing.

The only 2 ways I can see to eliminate the pitching, is either more down thrust, which isn’t really possible, or a throttle to elevator mix, adding down elevator with a corresponding increase in power. It doesn’t bother me that much, so I’m just living with it. The airplane flies so great, and is so badass, that it’s worth it to me. Good luck!

RCFlyerDan

My Feedback: (54)

OK, just bouncing back the way I understand. I’m not having thrust to pitching problems in the air flying. This is a rotation issue. IF there is too much down thrust causing the nose to pitch down, the opposite reaction requires more up elevator to overcome the down thrust. Once aerodynamics kicks in, the rotation is too fast.
I know the technique of a nice scale rotation.

Here is my BVM 1/6th F-16 to demonstrate what I am looking for with the F-4. I’ve flown the 1/6th F-4 and it will do a scale take off.

Craig B.

Hi Dan,

I had the same issue on rotation with mine. I resorted to using less flap on takeoff and that helped eliminate the problem.

RCFlyerDan

My Feedback: (54)

Thanks Craig for understanding the issue that I am trying to resolve. I’m going to add more air to my strut to increase the AOA. And use less up on TO roll. I normally take off with out flaps, and still jumped into the air. That’s why I moved the cg aft. But, I’m too tail heavy now. I tried flaps and didn’t really help. The 1/6th that I flew, the nose strut was fully extended. It was a slow, full scale rotation. The one that took off in the grass had a beautiful rotation. I think the drag on the mains helped.
I probably won’t fly it again until Thanksgiving weekend at an event. Will keep you posted.
Thank you for your insight.

Canadian Man

My Feedback: (1)

Second F4 Has Arrived.
Time to get ready to build the pair!

yeahbaby

My Feedback: (21)

The inner main gear door cylinder geometry is wrong. You will want to reposition and possibly switch to a small bvm cylinder to get proper geometry and throw. JMO, both kits I’ve built had to be repositioned maybe they fixed it over the years but I doubt it.
I love my F4s FYI just passing along my experience with these kits. You will want to reinforce the gear structure also.

ZivBit

Hi Guys

Just finished build of this one for my friend, Avi Ambar.
It is modified to electric retracts and doors, no air...
The modification was made by JP retracts, Shane. Works great so far.

Here are some pics of the build.

Cheers,
Ziv