RE: CJM F-4D Conversion and Build
 

Hi Kasper,

The wing bottom is not flat. This design is as close as you get to the real thing. CJM has got the details down pact.

I am using the foam wing covers to work on the wing. I need to go back and look at the instructions. I may have caped the wing with thicker balsa that I should have. I will work on it when I get home and post some photos. Thanks for your comment.

RE: CJM F-4D Conversion and Build
 

Ok, here is my problem, when I line up the leading and trailing edge, the center area of the outboard wing sticks up about 1/8. and when I let it rest on the wing foam casing, the leading edge of the outboard drops by about 1/8 also. one thing that I have done wrong was to cap the main wing with 1/8 balsa, the instructions says to use 1/16 balsa, however, I do not believe that could be causing the problem. I will contact Bruce at CJM, those guys are real good about helping with build issues.

RE: CJM F-4D Conversion and Build
 

Hi

Can't you sand back the 1/8 balsa capping to 1/16?

Mario

RE: CJM F-4D Conversion and Build
 

you can also introduce this scale fence and it will hide your small irregularity

RE: CJM F-4D Conversion and Build
 

Hi Mario,

No not easily and maintaining the same thickness the whole length. There is a 1/8 ply doubler that is installed on the trailing edge of the wing between the Aileron/flap and the main wing which extends in to the outer board wing.

Best Regards,
Mike

RE: CJM F-4D Conversion and Build
 

fill the outher wing with light weight filler? its easy and light

RE: CJM F-4D Conversion and Build
 

Mario,

Wow, never seen that close of a detail, thank you. so that is the leading slats in extend position, do you have a photo of it that is not extended? or were you referring to what looks to be some sort of grid work??

RE: CJM F-4D Conversion and Build
 

This fence is not present on ealry models like the F-4B/C/D.

Hope this will help.

Mario

RE: CJM F-4D Conversion and Build
 

I just checked the right wing and it seems to be ok, there must have been a small difference between the two outboard foam cores. I butted them together and the left one is bit thicker in the center section, which could have been caused by not having enough pressure on when I put the skins on[:@][:@].
I will line up the leading and trailing edge, glue and sand the center section in to submission :D:D:D then fill in for a nice transition.

The plans don't call for it, but I am thinking about laying a piece of carbon to strengthen this joint, top and bottom prior to glassing.

By the way, I plan to add panel lines to the wing and the fuse. I know of a way to use thin marking tape and use paint to build the surfaces and them remove the tape. I f anyone is got a better way, I am all ears.

Best Regards,
Mike

RE: CJM F-4D Conversion and Build
 

Hi all, this is a great thread and I am enjoying it immensely, so I have not chipped in until now. It is a real pleasure to watch a traditionally built model being constructed with a few modern techniques thrown in. I am a fan of the F4 having built and flown a scratch built version many years ago (twin K+B 45's) and also a yellow aircraft single more recently. Overlapping both these versions I have flown in both twin D/F and currently turbine powered form, the Tom Cooke version.
Having established my meager credentials I would like to post a few observations based on experience. I have built and flown a CJM Mig 15 which was probably the best model I have ever flown. This was a very rugged airframe but, having seen the excellent photographs of the build of this F4, I can see that using foam as a wing construction core, results in a wing that is full of fresh air. If it was possible to X/ray the wing it would be evident that once all the cut-outs have been completed for the aileron and flap servos and also the retracts, there is very littlel left of the wing structure. The modifications to the main wing spars on this thread go some way to transferring the flight loads but the landing stresses are another matter. I fly from a grass strip and have, over the years, imposed every concievable type of landing on the airframe. It took me a long time to develop my model to the point where I could ''dump'' itl on to our grass strip and not rip the gear out. Maybe I am not the best of flyers but I am eager to see this thread through to the test flight and look forward to the event. Best wishes to all. Ron.

RE: CJM F-4D Conversion and Build
 

Ron,

Thankyou for your comment. I am not a fast builder, with work, Kids, Wife and a mortgage, oh well you do what you can:D:D

quick update, I attached the the outboard wing to the main, the leading edge of the main ended up a bit lower than the outboard wing. I lookup John Reddman's BVM F-4 Build and I am affraid, I will have to cut the wing a part and reinstall. I will post photos later tonight.

RE: CJM F-4D Conversion and Build
 

As mentioned before, I had to cut the outboard wing from the wing to correct the alignment. I removed the 5 inch brace on the front end, as you can see from the photo that is not red paint on the leading edge, I stabbed my hand while using an exacto saw blade to cut the brace loose...ouch ouch [:@] [:@] Needless to say that was not pleasant. I used a 10" band saw to slice and separate the two with a little more hand-sawing. first picture is the misalignment , the rest are the corrected alignment.

RE: CJM F-4D Conversion and Build
 

Got the wings done, pockets filled and sanded. I will come back to the wing later. I am now working the Vertical fin and rudder. The vertical fin was some what done by previous owner all I had to do was to sand it down and form it. Next thing was to build up the rudder which uses ribs and sheeting to make a pretty strong but light structure. I have been looking at John Redmann's BVM F-4 build and got some pointers from him which I will share with you. The rudder control rod in BVM F-4 is different to what is provided with this kit, but since I am converting it to turbine, I would like to put a little beefier mechanism, if I was going DF, I would follow the plans. So what BVM does is to run the control rod under the rudder about a 1/3 way down and up in to the bottom side. It is pretty slick and scale looking. So what I did was to cut 1/4" from the bottom of the rudder (balsa) and replaced it with 1/4" thick plywood. I sheet the rudder after the modification. Once I make the control rod and the Mods, I will post a few more pictures.Here are a few pictures showing the progress so far.

RE: CJM F-4D Conversion and Build
 

Found a video on YouTube describing the F-4 control surface movements, it is pretty cool. Thought F-4 fans would enjoy.

http://www.youtube.com/watch?v=EXsTl...layer_embedded

Best Regards,

Mike

RE: CJM F-4D Conversion and Build
 

I have been working in the shop basically looking for parts that are missing. I am missing the stab hardware which I will have to order from Bruce at CJM unless I change the design similar to JL or BVM, have not decided yet. The other part that is missing is the rear parachute door, the gremlins must be living in my shop :D:D[:@][:@].

The door is not a problem, easy to remake, I basically made a balsa structure close enough to the profile and used Great Stuff to fill and sand. Once everything lined up, the foam structure was covered with Epoxy/Microballoon mixture and sanded to final shape. Rather than making a mold, I used the piece as a plug and covered with several layer of cloth and saturated with epoxy. Used a nonstick stretchable material and taped it up. Once cured, I made another batch of epoxy/microballoon and applied a top layer, I did not thicken it as much as I normally do so that the epoxy would somewhat self level itself, once cured, a little bit more sanding and now I have the door.

RE: CJM F-4D Conversion and Build
 

Going back to the rudder and vertical fin, I taped the parts to the fuse to check for fit, once done, I lined up the vertical fin and rudder with a gap of 1/64 between the top of the rudder and the fin and scribe lines for the counter weight. the section was cut, sanded and caped with 1/64 ply. I am sure there will be a little bit more fitting/sanding that will be done later.

There is gap under the rudder and the fuse for a aluminium tube per plan which I believe is the fuel dump. My plastic model shows that detail also. I will have to work on that as one of the last steps after everything is finalized and dry fitted.

RE: CJM F-4D Conversion and Build
 

I built the intake cheeks a while ago per plan and video instructions which are very detailed (sorry no build picture). I am dry fitting them in the fuse and am concerned that there may be a problem with alignment. If you look at pictures 1,2 & 3, the tip of the white intake sites above the line where the canopy would sit on. I do not have the canopy frame yet, need to order one, but just looking ahead, do you guys think that it is sitting too high?

RE: CJM F-4D Conversion and Build
 

Try swapping left to right and see what they look like.

RE: CJM F-4D Conversion and Build
 

Disregard that, it looks like you have the splitters on the correct side but possibly the cheeks are to high causing the splitters to be above the canopy line.

RE: CJM F-4D Conversion and Build
 

Hi Ronnie,

If I tilt the cheeks down then the bottom front end of the cheek will not be in line with the fuse. Do you have the same picture except a bit zoomed out? I wonder if bottom of the cheek is suppose to be in line.

BR,

Mike

RE: CJM F-4D Conversion and Build
 

See if this one helps.

RE: CJM F-4D Conversion and Build
 

Ronnie,

Thank you , that looks like the cheeks do tilt down, I will try that and see how it compares to the photo.

Happy NewYear,

BR,

Mike

RE: CJM F-4D Conversion and Build
 

Mike,

Check out this thread on the CJM F-4...might have some useful info for you.
http://www.rcuniverse.com/forum/m_33...tm.htm#3345640


Also check out this site for some great photos.
http://ipmsnl.netfirms.com/walkaroun...4E/F4-CH2.html

Happy New Year to you also... hope it brings you all the best.

RE: CJM F-4D Conversion and Build
 

Ronnie,

Thank you, that helps a lot, I see the alignment now, I should be Ok with a small tilt of the intake. The other site is also very helpful.

BTW, in your JL F-4, did you make the nose section removable? If so, is that where you have your batteries? I am thinking about that but am concerned about having long battery leads.


Best Regards,
Mike

RE: CJM F-4D Conversion and Build
 

Mike,

The batteries along with the dual retract/door air tanks are in the nose, but I didn't make the nose removable. I modified the original nose gear former and made a sliding tray to which the batteries are anchored. The battery leads are heavy duty and about 20 inches long up to where they terminate at the switch.