abufletcher

That makes sense. And I was planning on using the same technique I used on my Strutter's rudder: 3mm aluminum tube with 2mm aluminum tube inside with a thin strand of CF rod inside that...and all flatted to an oval shape. It's very strong. And light.

gabriel voisin

Hello Don,

it looks great, .....yes the scallops were a little bit to deep.
Your problem is the aluminum wire, the aluminum expands and it's not strong enough.
At the beginning I wrote, I use a welding wire in different diameters. (0,8mm to 1,2mm)
The wire is on a role and is used for the Inert gas welding.
In many airplanes was installed a turnbuckle in the trailing edge.
I use no metal strip to hold the wire, it's not necessary because the wire holds without the metal strip.
Something else, don't do it with a spring steel wire.

Have a nice day,....Matz

http://profi-schweiss-shop.de/images...ages/316_0.jpg

abufletcher

Actually, I think the aluminum welding wire was just fine (almost the same wire as the one you show), but I just gave it too much of a pre-curve. A suitable depth for 1/6 scale might have been about 1/8 inch. I pre-curved the wire to about 1/4 inch. And I just measured and that's about the same depth I have after covering. So it looks like the Koverall just pulled snug up against the wire and no further.


Matz, do you have any information on the shape and size of the rudder and elevator horns?

gabriel voisin

Yes I have.

gabriel voisin

Don, a question.
Why you build the ailerons not as the original with metal tube?
That was much more stable as a wood construction.

abufletcher

I really trying to understand why the elevator horns provided with the kit are SO large. They are a full 40% larger than the rudder horn, and about the same 40% larger than the bellcrank that controls the elevator pull-pull cables. At their current size they would stand out like a sore thumb on the elevator halves. I've also looked at the cable runs from the fuselage exit holes to the control horn tips and even with the shorter horn that's no problem.

In terms of the geometry of the pull-pull system, having a larger horn on one end should reduce the throw on the longer surface (elevator), right? A shorter horn would produce greater movement. But I wouldn't imagine any of this matters with a computer radio with EPA. As long as there's enough mechanical throw, it can always be reduced.

abufletcher

Believe me, I have thought about that. But I think there are some problems. First, since the airfoil for the wing isn't quite as thin as the original, the TE of the ailerons cut-out area is too thick (at least 1cm). So a simple tube structure, as on the original, wouldn't match up with the TE. Second, since I have no facilities to weld metal tube, the only option would be to glue it all together with JB Weld. That might work, but honestly, I don't know how strong an unsupported joint would be. Finally, even if I were to use aluminum tube, I still think I would find that the structure is fairly flexible.

The main reason I like the idea of making the ailerons from tube (even just CF tube) is that it would look authentic through the fabric and could have an authentic TE (instead of the wide ply TE they have now). GianFrancesco did his ailerons that way and they certainly looked great.

But you know, at this point, if I'm going to go "backwards" and redo the ailerons, I'll also have to redo the ailerons hinges, and the wing TE, and that means recovering the wings....and.... It would be a huge step backwards. []

*****

So some degree I have to accept that the model I'm building is ultimately a kit...it started life as the prototype for that kit...and kit that will now probably never see the light of day. [] So while there are some things I can change, other things like the structure of the wings, is basically unchangeable.

gabriel voisin

The most German WW1 aircrafts had tubular steel rudder.

No matter how thick the trailing edge on the wing.

You can do it with a thicker and thinner tube.
The German designs are also different because many manufacturers developed their own principle.
I will make a little sketch to show you what I mean.

Ähm, I don't understand what you mean with the rudder horns,...sorry.

gabriel voisin

greetings Matz,...

Nieuport nut

My Feedback: (10)

Don, does the cable from your horns go directly to a servo or to an intermediary bellcrank, ("walking beam")? You probably know this but if the latter, the size of the horns doesn't matter as long as the distance between the holes in the horn are the same distance as those in the intermediary. Then a single push rod from the servo gives you lots of adjustment latitude. If you are going directly to the servo then the holes on the horn must match up with the servo. Also, the sweep forward (or back), from the hinge pivot points also has to match. Otherwise, the cables will slacken and tighten as the controls are moved.

Watching with interest,

Martin

abufletcher

Yes, I'm aware of this and believe this is referred to as Ackermann geometry. This is one reason I'll need to redo all the horn because my scale hinges allow for a smaller gap. The kit's hinges are swept too far forward.


The cables attach to a dual bellcrank, which is operated by a single servo. As I mention above, the kit's elevator control arms are about 40% longer than the bellcrank. I can't see any reason for this. I know when Chris was first designing the kit, he had the stab placed very low and I know I talked him out of this as it looked wrong. Maybe the bellcranks are a leftover of that earlier design feature. Anyway, I would hate to have use such enormously out of scale horns on the model. I'd say they are close to 3 times larger than scale.

abufletcher

Matz, I'll give the metal tube ailerons another thought. I don't know the German word for "horn" but you can see the GRF parts on the left of this photo.

gabriel voisin

Ok, I understand.
You are doing a very nice job.
Then I want to help you and I think that's ok.
I've so much pictures of the building process, also of the BII.
As I said, I'll talk with Koloman because the drawings,.....if you need anything.
The german word is: Ruderhorn / Ruderhörner

Source: All the pics by CraftLab.

abufletcher

Fantastic photos! Thanks very much for posting them. I'm surprised that these ailerons don't have much built-in "twist" to them. From photos of the CI I've calculated that there was as much as 5Ëš degrees of twist.

gabriel voisin

Yes Don, that's right, the ailerons have a twist, but not 5 degrees.
When the ailerons is intall, then you can see it.
I've also the faceplate of the albatros company, ...it was mounted on the wing.
Have you seen it?

abufletcher

The twist on the original ailerons looks considerable.

abufletcher

I have a copy of the book on the BII from the Polish museum. Is this the same faceplate shown in that book?

gabriel voisin

I don't know Don, I've never seen a original wing in the Polish museum.
Please show me,...

Matz

TFF

If you ever did a BII you could do it as the RNAS one that was bought by the Royal Navy before the war started. It was well known enough to the British troops that when German ones attacked they thought it was their own plane.

abufletcher

I've been looking back through my HD and am finding reference photos I had completely forgotten that I had! Enough to make me realize how completely hopeless it would be to replicate every detail! [X(] For example, I found a few photos of the BII in the Krakaw museum taken by "Trev" (remember him?). They show the horns clearly and also show how the main control cable is attached to the horn via a shorter cable with turnbuckles on each end. One end of the turnbuckle slots into the control horn.

And, OF COURSE, I found this photo right after I epoxied in the rudder horn.

Note: Again and again, when I look closely at the old fabric covered aircraft, I see how really lumpy and textured the surface really was. There are seams and patches all over. Our models are typically far too uniform and smooth. It's like building a WWII model and not including panel lines.

abufletcher

Here's my version of the elevator control horn. It's much closer to the right size but still matches the bellcrank on the other end. It's made of a lamination of three layers of GRF (G10/circuit board material): 0.5/1.0/0.5 with gaps to capture the control cable end.

BTW, as another example of the Non-scale Knock-on Effect, notice the nifty bracket on the tail of the fuselage in the photo above. Unfortunately, the non-scale placement angle of the model's stab TE doesn't line up with this little feature. The bracket would have to be enlarged to nearly double the size to match up with the stab. Better to just eliminate it completely that to call attention to a non-scale feature.

gabriel voisin

Don,
nice control horn.

I have lookedon your photos of the BII and I must tell you that this is not the original cover, this fabric is restored, probably replaced.
The horns are structurally the same as the C and D types and they are 90 ° and not beveled.
The quality of the Albatros aircrafts was perfectly well and probably the best built machine in World War I. I want to show you what it looks like and how the quality really was.

abufletcher

Are you sure that (early production) Albatros CI aircraft used the same type of elevator (and rudder) control linkage? I see that in your photo, the horn as a hole in the top to hold the end of a turnbuckle. I could solder something like that from brass. But I can't find any photo of a CI showing that kind of linkage. The photo I'm (re)posting here is what is seen on the BII in the Krakaw museum. Accorsing to the information in the book, this aircraft was built in 1919 by Albatros Flugzeugwerke GmbH (Berlin-Johannisthal). But you're right that apparently it was recovered in 1986...in a somewhat careless manner.

But I believe the elevator horn shown in this photo are authentic and this is different from the one on the DIII photo.

abufletcher

I put together this little setup to remind myself of the practical dangers of going "too scale" in terms of the size of the elevator horns. The danger is that if the elevator horns are a true scale size only a very very small amount of movement on the bellcrank will produce a LOT of elevator throw...probably too much. At this point it would be extremely difficult to change the geometry of the bellcrank/servo linkage.

The size of the laminated horn I made last night is a satisfactory compromise. But I may have to alter the shape. I sure wish I had a reliable photo of the elevator horn on a BII, CI, or CIII. The later C 2-seaters and the D fighters clearly all used the same type of horn shown in Matz' photo above. The only close up photos I have are from the questionably restored BII in Krakow (actually carried out by restorers in Berlin).

abufletcher

Here's a close-up crop of the elevator horn in Matz' photo. You can see that there's something like a ball-end that fits into a cup in the horn (to allow it to rotate as the horn moves). The other end threads directly into a turnbuckle. I could probably make something like this with my M2 size turnbuckles and an M2 bolt. The cup part could be tricky but possible.

But I've eyeballed every single photo in the BII, CI, and CIII datafiles as well as the Cross and Cockade Albatros special and I can't find a single photo where the control horn seems to have the nice curve on the back as in this photo. They all just look like straight stumps as on the Polish BII.