Viewpoint

Note: Matthias kindly submitted this viewpoint article as a 7 page PDF file, complete with pics. This page is just a brief sample. For the full story - with better formatting - see his PDF file here: RC Jupiter Build Thread.

It all started when I was browsing the outerzone Gallery and I stopped by a tiny 36inch/90cm rubber low wing called Jupiter (oz2290). It was a very little bit like a caricature, the short fuselage, the long legs and that’s exact the fact when things come to be art. It’s a bit oversubscribed / direction of kitsch but stopped before being kitsch. Same feeling came up when looking at the GeeBees ;-).

So E.A.Ross did a super design job in 1947 and I felt a bit like Pasiphae or Ganymede, you might have heard of the Jupiter moons, ok there are quite more, coming back from time to time an surrounding the little Jupiter. In my thoughts I was aiming at a slight bigger version, but the characteristic appearance should stay.

Upscaling to 59inch/150cm was the first goal and the Prop should be 19 inch when keeping the scale exact!

I called Mr. Reisenauer, a German electric engine and gear producer. He is always helpful and said a Fiala Prop could work on a 2221/16 KV2012 14,8V engine with 1:5 gear at 2300rpm bringing 1152g gr of static thrust and 64km/h pitch speed. Wow, that sounds great, the rotation speed comes down to a number that is comparable to the rubber powered models, this will add further scale impression to the model and so the set was ordered including prop and all you need. I ended up with a span size 1:1 to the prop with 56 inch/142cm.

I’ve done a few projects and have my own way to go. In the beginning I collect all the stuff I can find, this was very easy here, due I found all I need @ outerzone, Thanks Steve for providing us with this mega information which is a huge source of ideas to me. Yes next project is already running when I drop this lines ;-).

So I scaled up the original plan from E.A.Ross in my CAD and started. Don’t want to go too deep into construction details, but you can easily spend a few hundred hours at the PC.

Easiest way is to sketch over the original plan, that should be in exact x and y enlargement.

I used a Selig S 7055 flat bottomed low Reynolds Profile on the wing and a HQ Acro 12% for fin and stabilizer. Both behave uncritical and the Selig carries up to 15° before stalling combined with low drag. Here you can see the Jupiter construction, a few things needed to change from the rubber model. The wing joiner is from carbon self-made direct in the holm between the belts, the tailwheel is steerable, Spinner bought from Simprop fibre glas fits perfect in the contour and as I wanna keep the dihedral it is only steered by elevator and rudder. I like these old ones without aileron, it keeps the old character.

Once this work was done, we needed a drawing and all parts that should be lasered had to have an dxf-file. A diligent but routine piece of work. You can download the plans here at outerzone. I placed all parts from one material on a sheet that is sized with the measures that are normally used for the boards. With all this done I went to our local hobby shop www.FS-Modelltechnik.de . Frank Schulz started to laser wood some time ago and he is in my eyes a real perfectionist. So to keep up a little I need to add some breaks in the laser lines, so that a.) the tiny parts didn’t fall out and b.) the bigger parts that have sometimes tension inside the wood, keep their form until the complete cut is done. I cut some slots for the trailing edges in the fin and stab ribs, but that was too much heat for the sharp ends and burns too much wood. I redesigned that to a single cut, that needs to be sanded wider carefully. Frank is offering this Laser-service to anyone and if you are fancy to build a Jupiter, pick up the dxf-data here and ask. Feedback from anyone who build the RC-Jupiter is requested definitively. If you need held during the build, please ask for advice. Or go to https://www.fpv-treff.de/forum/index.php?threads/jupiter-von-frog-the-bringer-of-jollity.444/

I started the build a few weeks before I got these parts with a foam block for the vacuum canopy, it was 3-d milled to the CAD-step file and glassed with 3 layers of 105gr fibre. Filled and sanded to perfection.

The woodwork is easy due that all parts fit together like a puzzle. Wings and stabs are built on a jig. The jig is enclosed in the laser parts. For the wing the jig is made from 3 Balsa strips numbered from 1-3. The exact location is shown on the plan. The lower belt is placed on Jig2 the lower trailing edge followed by the ribs...

Note: Matthias kindly submitted this viewpoint article as a 7 page PDF file, complete with pics. This page is just a brief sample. For the full story - with better formatting - see his PDF file here: RC Jupiter Build Thread.

See Jupiter RC (oz12854) for the RC Jupiter plan (and CAD file) download.

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