Rieseler R III scale 1/25

[Anyun]

I guess most of us European free flight scale modelers have been impressed by the Czechs and their style of building. This model was started to test out some of their techniques. I choose the Rieseler as it's a good looking aircraft with simple lines that one should be able to build quite fast. Two years later I have to concede that "quite fast" is not the best description of this build...

The plane I am building is the one preserved in Sweden. It was built in 1922 with parts imported from Germany. After having flown it for some time, the owner emigrated to the USA. The Rieseler was put in storage and eventually ended up in the Arlanda aircraft museum.

There is a good scale plan made by Björn Karlström and I'm using it as a build plan, mostly keeping with the scale structure.

Here is a photo of the wing being built. The ribs were made by cutting them from a pre-formed structure built from two balsa sheets with "spars" inserted that becomes vertical internal rib stays when the ribs are cut out.

[Anyun]

Next photos show the wing tips being laminated and the basic wing structure completed. The weight is 0,77g, but note that this is not a full size peanut.

[Anyun]

The last steps in building the wing - ailerons and central part. The final weight of the wing structure is 0.93 grams

[Spiros]

Very interesting airplane and beautifully made!

Are the ailerons adjustable? Or this was just the scale approach?

[ramses]

Beautiful build and very light!!

Cheers, Ramses

[Lastwoodsman]

1922  Riesler plane                      Thur July 23 2026

Hi Anyun.   your ribs sliced off of that pre-made balsa structure,  look really good.     That is a new trick for me ...

Lastwoodsman
Richard

[TheLurker]

The rib assembly technique is new to me too.  Is it any quicker than the usual split rib method and, how do you cut the ribs cleanly out of the "block"?  Is there much wastage/breakage?

The results are very impressive.

[Prosper]

Wow, those ribs. Impressed.

Stephen.

[Anyun]

Thanks for your kind comments! I did a quick sketch explaining how the ribs were made. First, the balsa sheets were wetted and formed using the "little hut with a hot roof" shown in the first sketch. When they are hot formed like that they take a permanent curve.

Then the whole assembly was put together as in the second sketch.

The cutting out of the individual ribs was done using something flexible with a hard edge as a ruler and cutting with a razor. After each rib had been cut, the edge of the rib assembly was sanded to ensure a nice surface for the next rib.

First I tried fixing a piece of razor blade on supports above a base plate - the plan was to slice off the ribs sliding the "package" through this device, thus ensuring equal width of all the ribs. This unfortunately didn't work, an ordinary razor blade was just too flexible, and when I tried a thicker type of blade, the balsa sort of got crushed.

This method of making ribs is most suitable for constant chord wings. A small variation in chord can be handled just by cutting some ribs a bit shorter, but for a true tapering wing you would have to make a tapering rib package. Probably not impossible, but definitely a complication.

Re. the ailerons, they are adjustable. They are mounted on thin (about 0.3 mm I think) copper wire unwound from some kind of electric coil. The copper wire was glued to the wing but not (yet) to the ailerons, as covering would be hard if they were not removable.
Making the separate ailerons was the most fiddly step in building the wing.

[Spiros]

Really impressive. Many thanks for sharing this method. First time for me and definitely would like to give it a try at some point.

The adjustable ailerons are for mainting a certain roll on the airlplane or is it going to be R/C?

[OH-13-H]

excellent work!
I see you also got a camera.

[Anyun]

I see you also got a camera.

Not as good as yours though. And for some reason it does not seem to work with colour film 

[Anyun]

The adjustable ailerons are for mainting a certain roll on the airlplane or is it going to be R/C?

It's going to be a rubber powered freeflight model, so the adjustable ailerons are just for trimming and scale fidelity. When using adjustable rudders/ailerons, it's important that they are hinged with a material of suitable flexibility. Too flexible, and the rudders will change position at every landing. Too rigid, and it's the structure that will bend (or break) rather than the hinge when you make an adjustment.

When the model has been trimmed, it's a good idea to lock the rudders with a drop of glue to prevent accidental repositioning.

[Anyun]

For the covering, I'm again following Alfery et al. in using Tengujo Kashmir paper (9g/m2). This is a lightweight Japanese tissue that is easy to work with and has a low shrinking force, i.e it will not as easily cause unwanted warping as a tissue with stronger shrinking.

The main disadvantage with this paper is that it is very porous. Dope alone will not fill the pores. The method I'm using (again stolen from the Czechs) is to first dope the tissue with thin dope, and after that 5-6 coats of wallpaper glue (I'm using Metylan).
The wallpaper glue fills the pores and weighs next to nothing. The purpose of the first coat of dope is to make the tissue somewhat less vulnerable when wet. When using this method on thin double covered surfaces, great care has to be taken to prevent the tissue from sticking to the tissue on the other side.

In the photos below, the wing is being covered. The tips have a small amount of double curvature, hence they are covered with separate tissue pieces. To prevent the whitish balsa from shining through after painting, I pre-coloured the structure with pastel.

[Anyun]

In the photos below, the wing has been covered and is in the process of being coated with the wallpaper glue. I let it dry weighted down on a frame to prevent warping of the thin, undercambered wing.

Weight covered and doped is 1,38g