Hi, I've decided it's time for a new project. I've had several things in mind but finally settled on the Junkers Ju390.
The Ju390 was a version of the Ju290 built for long range, it featured extended wing panels with 2 extra engines making a total of 6. It also had extra sections added to t[he fuselage. It was Junkers entrant in the ANERIKA BOMBER project. Only 2 prototypes were built before it was cancelled The V1 from a Ju90 and V2 from a Ju290, I will model the V2.
There is a lot of speculation on the net as to what was achieved by these aircraft. One was reported as flying to within 20 Kims of New York and safely flying Home! While on the other hand it was rumored that pnly one was built and the photos of the V2 are fake. My main reference for this type of aircraft Is William Greens "Aircraft of the third
Reich' and he gives the SERIAL NUMBERS of both donor aircraft as well as precise information regarding fuselage lengths.
And now for the Hodel. I blew up a 3-view off the Net to 1/48th scale ,which is 41.75"and checked the sizes and sections against a 1/72 scale plastic model kit lent to me by hy brother, surprisingly they were all within 1/16" to 1/8",Amazing.I started on the fuse first which is a particularly odd shape but I manage to find flat sides so I was able to start in the normal way by building 2 sides over one another I used some aluminum angle to keep the 2 top longerons straight. Then standing them up and fitting the spacers I was able to make a box. Sorry no photo. The top formers were set in place with a square piece of wood covered with sticky tape, so the clue doesn't stick. and held on with a rubber band. Finally all formers were fitted and grooved for the stringers. The fuse will be covered in sheet balsa.
Thanks, that's it for now.
Dave
Just thought you might like to see what it looks like when finished.
Dave
Quite a project Dave, I look forward to following this one.
With 6 engines I'm assuming it will be an electric power model ?
I see you've picked yet another perfect indoor subject. :)
Looking forward to seeing pics or film of this one in the air.
Yep - another design that Dave would be hard-pressed to ignore. Right in his wheelhouse as they say. Look forward to the progress. Tim
Thanks Fellas, yes it will be electric, if I ever get the right motors! I ordered some before Christmas but when they arrived they were the wrong ones, they were very cheap so I told them I will keep them but to make sure they send the right ones, well the wrong ones arrived again. This time I tried a different department and have hy fingers crossed that third time is a charm.
Dave
Hi Fella's, I've put the fuse aside and built the Center Section and then I will build the tail unit. This way I can set the incidences and decalage and that way I can then sheet the fuse. The C/S was pretty straight forward, I cut 2 ribs from 1/16th Aluminum and cut a stack of 1.5mm blanks bolted it together and carved and sanded them to shape Next I made some 2.5mm Blanks for the end ribs and for the C/S.
I find it more accurate to carve a few ribs at a time. The spars are all 3mm and the L/E is 6.5mm. I've braced between the spars to help against torsional twisting with the 6 motors. I've switched over to Aliphatic glue to try and make a neater job than CYNO, but it doesn't seem to be working. Not sure if I can thin it with water or not as that would help. Might have to do some testing.
Dave
Hi, Well I have built the Tail Unit, It looks fairly small so I enlarged it 15% hoping that will be enough. I started with the Stab and as it is quite narrow I have braced it well to try and stop it twisting from the extra forces of the twin fins. As the Stab has dihedral I made up some joiners from 3mm ply to fit to the L.E. and the spar and glued the halves together with Arildite for a strong bond. It was then sanded to shape. The Elevators were next and simple. They were attached to the Stab with 3 pieces of copper wire so they can be used for trimming
Next up were the Fins which I also increased 15% so they did not look out of place with the larger Stab. The Fin and Rudder were laid out together and then sanded to shape, Finally they were joined together with 3 pieces of copper wire. They were then test fitted to the Stab.
Dave
A bit more progress, I started with the cabin and blocked it up with 6.5 and 10mm balsa sheet. Looks like it would be home on the Flintstone Flyer ;D Next I shaped it up and cut out a block for the nose. Finally shaped it up and gave it a coat of Dope n Talc to seal and hide the joins. Molded and fitted the top decking from 1.5mm sheet.
Molded the rear lower fuse and front lower fuse cover. Got a bit carried away and forgot to take some photos of fitting the rear fuse cover and finished off the sheeting of the fuse. Finally the fuse so far with a coat of sealer. I will leave the lower front of the fuse open so I can decide later where I need to fit the hatch for the battery and speedies. That's it for now.
Good grief Dave! It's a bit small isn't it and only 6 motors? :)
That is a major undertaking! looks great
Cheers
John
Thanks John.
Hi Dave! Probably you already have this photo? It's from one of Mt Japanese books.. probably the view the spectators will have!
Hi John, nice to see you here, hope things are going OK kor you.
Yes that is a familiar photo, I believe it was taken by a man from NSW who was in the British Merchant Navy.
Hi Dave! Good to see you here too! Hopefully that means that you are coping with your challenging situation?
Yes, it's nice to be back on HPA! I've got a bit more time now, so I'm trying to round up my " ducks 🦆 ", in an attempt to get them into a row! But hopefully that will mean cutting wood soon! It's cool that someone photographed your plane flying and the photo wasn't lost! I'm watching with interest as usual!!
Progress has been a bit slow lately but I have managed a bit.
Made up the 2 outer wing panels Photo 1. Photo 2 shows the outer wings carved and sanded. The out panels will be made detachable for transport and mainly to prevent damage in a hard landing.
In Photo 3 the dihedral is set and 1/8th brass tubes are set in place against the spars. A wood spacer with slots to clear the brass tubes is clamped in place between the root ribs and the tubes glued in place. Photo 4 shows the balsa glued against the tubes, these will be filled with glue and vertical grain gaps glued in place over the tubes.
The Root ribs are faced with 1mm ply and then sanded Photo 1
The center section has the root ribs faced as well and I have sheeted the front of the wing and have added sheet for the nacelles. I should have thought about this when I laid out the ribs and spaced them to suit the nacelles, it would have been neater. Photo2. Finally the completed wing so far. Photo3
Dave
Hi, next step is the mounts for the motors. As the wing is set at 3degs. positive Incidence I wanted the motors to sit level with the fuse so they already had 3degs. downthrust relative to the wing. the motors will be adjustable so I have drilled the motor mounts above the center line so I can increase the downthrust if required and the prop shaft will be in the center of the cowlings.
To this end I made up a jig with some brackets set at 3degs.to hold the wing in place, the ply mounts could then sit squarely on the bench while the epoxy dried. Photo 1. Photo 2 shows the completed motor mounts while Photo 3 shows the underside mounts and gussets as well as the strips for mounting the lower Nacelles. Next up is making the inner Nacelles. in Photo 4 you can see the jig I made to hold the form in place. The inner Nacelle has a bulge on the lower side to contain the landing gear so I spun the form into shape on the lathe. I then cut off the lower third and replaced it with a block of balsa and carved it to the bulging shape. I then mounted it in the jig with the underside up and molded a lower nacelle. I the removed the screws and turned it 180degs. to mold the top Nacelle.
Here are the Photos
That's a neat clever approach to making the nacelles and jigging the motor mounts, Dave.
Happy building.
John
In Photo 5. you can see the setup for the Outer Nacelles. As they are the same upper and lower I spun up the form in the lathe and mounted it so I could form the Nacelles, Finally Photo 6 shows the top inner and outer Nacelles in place.
Thanks John.
Wed march 25 2026
Hi dputt7 Dave. That is a very interesting and excellent build of your six engine Junkers Ju390 plane! 8) Thanks for all of the pics and info!
Lastwoodsman
Richard
Thanks for your interest Richard
Hi, this seems to be going on forever :o .
I've managed to cover all the flying surfaces with PolySpan and given them a couple of coats of dope to seal them. PHOTO 1-2.
Next up I've fitted the Nacelle moldings for the top and bottom of the wing Photo 3-4 shows the top fairing and Photo 5 shows the underside with the Fatter Nacelle to house the landing gear, I have a fair bit of filling and touching up to do yet!
You will notice an orange stain on the covering, this is caused by using debonder to remove some unwanted spots of glue. Just as well it will be painted. Finally in photo6 you will see I have made a start on the engine cowlings, Plunge molding them over a form to make the front cover. That's it for now.
Dave
The rest of the Photos.
Quote from: dputt7Hi, this seems to be going on forever :o .
Great work Dave. Big project . . .:)
As Stephen says... Very much enjoying watching it come together this end :-)
Thanks Stephen and Chris, I appreciate your interest.
Dave
I remember you having problems with some electrical doo-dad earlier on - did you get to the bottom of that?
Hi Jeremy, no I did not! That was concerning the wiring of the ESC which I spent a fair bit of time trying to work out. Have put it all aside and will try to work it out later, meanwhile I will use some HX1811-2000 brushless motors and I think I have enough 6amp ESC's lying around. It means that there will be a weight penelty over using the others that also used scale size props.
Dave