NHI Kolibri N-3, scale 1:48, scratch build

Today the weather over here was very bad; cold, biting winds and rain, lots of it, so quite a bit of time on my hands to make some progress. I added rivets to the new torsion box, joined the torsion box to the main rotor mast and applied a first layer of finish. So far I am pleased with the results:

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RDN1954 said:
Today the weather over here was very bad; cold, biting winds and rain, lots of it, so quite a bit of time on my hands to make some progress. I added rivets to the new torsion box, joined the torsion box to the main rotor mast and applied a first layer of finish. So far I am pleased with the results:

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Beautiful painting with a nice outcome of the structure and the rivets, Johan.
Gr. Peter
 
RDN1954 said:
Today the weather over here was very bad; cold, biting winds and rain, lots of it, so quite a bit of time on my hands to make some progress. I added rivets to the new torsion box, joined the torsion box to the main rotor mast and applied a first layer of finish. So far I am pleased with the results:

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Good morning Johan. I’m with Peter here. In particular I like the way the rivets look with the red. Cheers Gr
 
Peter Voogt said:
Beautiful painting with a nice outcome of the structure and the rivets, Johan.
Gr. Peter
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GrantTyler said:
Good morning Johan. I’m with Peter here. In particular I like the way the rivets look with the red. Cheers Gr
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Daniel20 said:
Your detail is outstanding Johan. I really like what looks like turnbuckles pinned to the main vertical column post and a horizontal pipe.
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dockattner said:
Wow! That looks really great! I appreciate your preservation of scale.
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Thanks for your favorable comments, it's appreciated.

The way the rivets come out is a stroke of luck, rather than a stroke of genius. I hope the next two coats will not entirely cover up the slightly darker rivets. My earlier build and painted parts suggest it will be okay.

Very attentive, Dan, the two lateral struts do contain shock absorbers rather than turnbuckles. The original has the shock absorbers partially mounted inside the strut. I couldn't get that to work into a believable configuration. My compromise is more like a turnbuckle than a shock absorber, maybe something to look into on a possible second build.
Here a more detailed sketch of the lateral strut:

IMG_0898.jpeg

In the end of the day I am aiming at having a convincing looking model. To me that means that I have to avoid out of scale details to the best of my abilities. It's nice to read that I'm at least partially successful.
 
It was high time this little bird started to use her own feet. Having established that, the associated action needed to be taken, thus the skids were fabricated, using 3mm brass tube and the four struts, using 2mm brass tube. I drilled 0,8mm holes in the cross tubes and the skids and used leftover cut-off nails in order to be able to positively align the struts. After a little effort I was able to add the skids to the earlier made assembly of the main rotor mast and the torsion box. In this case I used CA glue to fasten the various parts together. The earlier mentioned pins gave the results I was aiming for; robust skids.

Here the results of a few hours work. I also loosely added the center fueltanks and my earlier effort in scale 1:48:
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A view from the right looking forward. Here I temporarily added the instrument panel:
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RDN1954 said:
It was high time this little bird started to use her own feet. Having established that, the associated action needed to be taken, thus the skids were fabricated, using 3mm brass tube and the four struts, using 2mm brass tube. I drilled 0,8mm holes in the cross tubes and the skids and used leftover cut-off nails in order to be able to positively align the struts. After a little effort I was able to add the skids to the earlier made assembly of the main rotor mast and the torsion box. In this case I used CA glue to fasten the various parts together. The earlier mentioned pins gave the results I was aiming for; robust skids.

Here the results of a few hours work. I also loosely added the center fueltanks and my earlier effort in scale 1:48:
View attachment 501146

A view from the right looking forward. Here I temporarily added the instrument panel:
View attachment 501147
Click to expand...
This is good stuff Johan. Nice. Cheers Grant
 
RDN1954 said:
It was high time this little bird started to use her own feet. Having established that, the associated action needed to be taken, thus the skids were fabricated, using 3mm brass tube and the four struts, using 2mm brass tube. I drilled 0,8mm holes in the cross tubes and the skids and used leftover cut-off nails in order to be able to positively align the struts. After a little effort I was able to add the skids to the earlier made assembly of the main rotor mast and the torsion box. In this case I used CA glue to fasten the various parts together. The earlier mentioned pins gave the results I was aiming for; robust skids.

Here the results of a few hours work. I also loosely added the center fueltanks and my earlier effort in scale 1:48:
View attachment 501146

A view from the right looking forward. Here I temporarily added the instrument panel:
View attachment 501147
Click to expand...
great progress Johan
 
Henk Liebre said:
Just catching up on your missed post recently

Beautiful frame, I love the red, the nails give a nice added value to the whole Building

without a drawing and scratch is not an easy task

Great respect

Regards Henk
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Hey Henk,
Good to see you're alive and kicking.
I agree with you, those rivets turned out really well, with a big thank you for @Peter Voogt.
As stated before, it's a real challenging build, where I need to take time to work out many details, make prototype parts, threwing them in the bin and start again. That, combined with some anxiety as to whether or not I will be able to complete the model, makes this a nice pastime...
Kind regards, Johan
 
This week I started on something I've been postponing for quite some time now, namely the flight controls.
There is, as I mentioned before, very sparse information on this helicopter and that applies to essentially all details.
The first set of controls I need to be building is the collective pitch control of the main blades, since part of the system is housed inside the torsion box. I need this system in place in order to be able to close the torsion box, which in turn is needed to be closed to allow installation of the floor, seats and instrument panel. With me so far?

I have two drawings helping me out with respect to the collective controls on/in the torsion box. Upfront I'll tell you I will be deviating from these drawings, just to make it work...

Below, encircled in red, is the collective pitch control system.
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And here an assembly drawing of the collective control, with the pushrods and levers, ultimately driving the control rod, attaching to the rotor head
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After a few days of fiddling and playing around a little bit, I came out with this:
It's a dry fit, so not everything is aligned properly, but this was just to ensure the fit and functionality of this part of the collective control system. The push rod nicely clears the shaft for the pilot seat support.
To make it even more complicated, the pitch control system of the tail rotor uses the same shaft (shown in the left hand side of the picture) as the levers and push rod of the collective. I have some ideas on how to tackle that issue, but first things first.

For reference: the pitch between the shafts and the push rod attachment is approx 4mm, 0,16".

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RDN1954 said:
This week I started on something I've been postponing for quite some time now, namely the flight controls.
There is, as I mentioned before, very sparse information on this helicopter and that applies to essentially all details.
The first set of controls I need to be building is the collective pitch control of the main blades, since part of the system is housed inside the torsion box. I need this system in place in order to be able to close the torsion box, which in turn is needed to be closed to allow installation of the floor, seats and instrument panel. With me so far?

I have two drawings helping me out with respect to the collective controls on/in the torsion box. Upfront I'll tell you I will be deviating from these drawings, just to make it work...

Below, encircled in red, is the collective pitch control system.
View attachment 503691

And here an assembly drawing of the collective control, with the pushrods and levers, ultimately driving the control rod, attaching to the rotor head
View attachment 503689

After a few days of fiddling and playing around a little bit, I came out with this:
It's a dry fit, so not everything is aligned properly, but this was just to ensure the fit and functionality of this part of the collective control system. The push rod nicely clears the shaft for the pilot seat support.
To make it even more complicated, the pitch control system of the tail rotor uses the same shaft (shown in the left hand side of the picture) as the levers and push rod of the collective. I have some ideas on how to tackle that issue, but first things first.

For reference: the pitch between the shafts and the push rod attachment is approx 4mm, 0,16".

View attachment 503695

View attachment 503696
Click to expand...
That looks very promising, Johan. The second technical drawing is very interesting. To see how complex and multi function some parts are. Clever inventors!
Regards, Peter
 
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