Warbird Replicas Ju88 Night Fighter build

[gillyg1]

I personally - if WR or should that be RW ,were to produce another twin, would prefer a beaufighter for a pair of lazers, which would obviously have to be slightly larger size, but we've been down this road before on another forum.

Ron, following your thread with interest , being i/c. ?

[Ron Gray]

Thanks @gillyg1. To get something bigger I think we would have to look elsewhere, Richard has a knack of producing this size ‘planes that not only build quickly and really look the part they also fly extremely well, changing his formula may well upset things. Personally I would dearly love a larger Mosquito that I could fit 2 Laser 200i with gearbox in as that would truly be something else. But if Richard was to bring out his version of a Mossie you, and everyone else, would have a hard job preventing me from being at the head of the queue to buy it!

[Chris Walby]

As Richard has eluded to all along its about sufficient numbers of people wanting to build affordable well flying models. IMHO if you want a mossie then there is the SG one already available. If fails to meet Richards criteria both in electric or IC formats regarding set up cost, but looks ok and flies well with a pair of Laser 70's. My point is that it has already stolen a number of potential buyers and its numbers of kits Richard needs to make it worth while. Almost everything else is niche and doesn't get the numbers.

I would have to say if it was a mossie then I would have one but it would be electric with a sound unit.

[Ron Gray]

Anyway back to the build. I cut the new firewalls out using my scroll saw then put them in the lathe to true them up. 
 

Shown next to original firewall

 

Twice the thickness 

[Ron Gray]

Just looking at photos of the full size, in particular the ailerons which seem to hinge below the surface against a pronounced airfoil section on the wing false TE. Anyone care to explain the advantages of hinging them this way?

 

 

 

 

 

Interesting ‘stop’ on the outer, wingtip edge

 

[Bob Cotsford]

Are they slotted flaps Ron?

[David P Williams]

They're frise ailerons aren't they? Help to reduce adverse yaw.

[Ron Gray]

@Bob Cotsfordthey're ailerons Bob, and I think that David has got it, they are Frise ailerons. Tempted to try and replicas them but don't think I will!

 

Of course, this is the problem when looking at full size photos, I noticed that the couple of fill size ones I've been studying don't have elevator balancers at the tips, whereas Richard's kit has them. So I merrily went away and redesigned the tailplane and elevators. Later on this afternoon I downloaded a couple of books on the JU88 and having flicked through the pages I suddenly came across line drawings for the G-6 variant and guess what, it has balancers on the elevators.The model is the G-6 variant so I will have to adjust them back!

 

 

Edited June 17, 2021 by Ron Gray

[Ron Gray]

Continuing the redesign of the nacelles involved a lot of time measuring and remeasuring then offering up the dry assembly to the wing to make sure that the orientation of the motors allowed the exhaust to exit as close to the full size exhaust stack as possible. Then it was a case of epoxying the framework together.

 

As I showed earlier, the side plates for the nacelles needed to be trimmed back due to the extra length of the I/C motor.

 

 

They actually needed 20mm cut off but first I cut out the middle section to leave 2 tongues

 

 

Then I cut out mounting slots in the new firewalls.

 

 

So when dry assembled

 

 

After final measuring I was able to determine the orientation of the engine and then fitted the flanged nuts

 

 

I then assembled both nacelles using epoxy and trimmed back the nacelle side tongues

 

 

Motor mount loosely attached. Note that I cut out a section of the top of the motor mount to allow the motor to fit tight against the firewall (thanks for the tip Richard).

 

 

Whilst all that was going on I also assembled the tail feathers

 

 

And these are the tip ends which will need to be cut and reformed due to my mistake in building the wrong model (see above)

 

 

Edited June 17, 2021 by Ron Gray

[Bob Cotsford]

1 hour ago, Ron Gray said:

Bob Cotsfordthey're ailerons Bob, and I think that David has got it, they are Frise ailerons. Tempted to try and replicas them but don't think I will!

That'll teach me to speed read posts!

[Ron Gray]

A little bit more done, although it has taken a bit of time to do it!

 

Tank/throttle servo tray added (screwed to bearers)

 

 

4" drain pipe cowl (thanks Richard) cut out for cylinder, main needle and fuel pipe

 

 

Front cowl cut out for engine

 

 

Loosely assembled

 

 

Just got to do it all again for the other nacelle!

[chris collis]

Just seen this highly interesting build article for the kit build for the Ju88.I have an old electric/pss 72” one but could do with the canopy renewing.Would anyone know if it’s possible to buy a spare bomber canopy to fit?my original mould has seen better days!many thanks 

[leccyflyer]

I remember your model well from the early noughties - here's  a wee clip from the Blackpool Fly-in. The video quality that could be uploaded then was pretty low res, but it gives a good impression of how well the model flew. Aces High March by Vale Royal Schools Band.

 

 

Happy days. ?

[chris collis]

So surprised that anyone remembered my Ju88 after all these years!Then it was powered by two speed 600 motors and nicads and it's still set up to fly both as electric or pss but now mainly as pss.It's now nearly 28 years old and still gives a lot of fun but the canopy now could do with replacing.Thanks for the video,I never knew it existed after all these years!Hear's a couple of brilliant photos taken by patmac in it's present Sicilian camo colors at my local cliff soaring site.

[Ron Gray]

I haven't gone to sleep or got bored with the build (yet???) but I promised to only post stuff to do with the I/C 'differences', so, whilst photos have been taken of the normal build parts of the tailplane , fin etc, here is the work that I've done to the cowls. These cowls have taken up a lot of building time but it doesn't show in the finished item!

 

I decided to fit the ply cowl covering before fitting them to the wings as I felt that it would be easier to do that now rather than later. I drew up a template on paper and then transferred that to the ply which was cut using scissors. I then stuck it to the cowl framework using cyano which will be reinforced on the inside when I fuel proof / epoxy the cowls. I've also added an additional thin strip of the same ply to the rear edge which will provide a 'seat' for the plastic rear cowl covering.

 

 

I did add a strip of balsa to the back of the firewall to provide a wider surface to stick the ply to. I've also added strip balsa to the top edge of the ply to give it some lateral support. Notice the angle of the ply which is due to the down thrust built into the firewall.

 

Drain pipe motor cowling attached, all lines up.

 

 

 

[Ron Gray]

I know I said I wouldn't but I thought I'd try to make some Frise aileron hinges out of Robart pin hinges. Over-bent this one but I think it will work, although still not decided if I will go with them.

 

[leccyflyer]

Frise a Jolly Good Fellow!

[Piers Bowlan]

Ron, do you think you could share a diagram, with your modded Robart hinge overlaid, to illustrate how it would work? 

[Ron Gray]

@Piers Bowlanthank goodness there’s someone else out there apart from @leccyflyer! In answer to your question, I will be mocking up the aileron later on today as I want to make sure it’s going to work (I’m sure it will). The unknown is what it will fly like with Frise ailerons, it’s OK on the full size but not all things transfer in the same way to models, so do I risk it? Those who know me probably already know the answer to that!

[Chris Walby]

I am also here watching. If it flies like a dog or doesn't fly then you will know its something you have done as the others built before have all had good reports.

 

What could possibly go wrong?

[Ron Gray]

Good man @Chris Walby.

 

As you say, what could possibly go wrong ?

[Ron Gray]

Here is a (very) rough mockup, the exact location of the location of the hinges (and maybe shape) needs a bit of work

 

 

 

[Ron Gray]

'Location, Location' sorry guys, this wasn't about moving house!

[john stones 1 - Moderator]

Ah the old Frize frame tutorial eh. ?

[alan p]

Hi Ron 

Would removing the hinge pin and using pcb board or similar for the bracket produce a stronger fixing. good luck with the mod?