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        Build Log Horten Ib 1/8 scale

#1 andrecillo76 Sep 29, 2012 01:54 AM

Horten Ib 1/8 scale

the german "Gang" stiked again :D. We have been working on a 1/8 scale Horten Ib in the last weeks. Jörg has been dreaming of a full scale H-I since I know him. Thus his acronym of HortenI. So it was about time to build at least a small one. The procedure was as always: number crunching, CAD work, milling, building and finally flying. Of course, it's made of birch and poplar plywood as always.

Here is a photo of a renovated H-Ib in argentina


There were actually at least two version of the H-I. The first one - built in their youth by Reimar and Walter Horten in their family's home - differs in shape from the Ib, which seems a little bit more modern. There are some plans in the USA of a Ic, but I think it was never built. But I'm not sure.

Maybe Jörg loses some words on it before we start with building pictures.


#2 Jon Snow Sep 29, 2012 02:07 AM

This is gonna be good!
Regards Stuart
Just found you on Vimeo.You have been busy-bc-def.................:D

#3 HortenI Sep 29, 2012 12:32 PM

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Andrés thought I should write some words about the H I and the recreations.

At the moment I am writting an article for the VGC-News which will be published 2013 so I cannot write so detailed.

Horten Nurflügel are a part of my family history especially the H IV, H VI and the H IX because some relatives and friends worked for Walter and Reimar during WWII and after it.
It was like a gang where everyone helped eacht other all the years.
And it was a pleasure to met them when I was young(~7 Years) but the bad thing was at this time the only thing I knew about Horten was that the US Forces captured most of them and took them to the US.
Today I knew more and I am still working about my knowledge.
For me the Horten Ia is their masterpiece because its unbelievable that they calculated, built and flew such an aircraft at there age.
Thee thing is when they talk about Horten they think about the three types I mentioned earlier but not the small (12m) triangle which they took to the Rhönwettbewerb 1933 and won a prize because today is all about the high ratio.
The H Ia
Also there is Horten Ib which was built and first flown in the mid 1950ies which has got some aerodynamic modfications and the typical argentinien Horten midsection and another skid. It was a sucess so the restored it and flew it 2008.
The Ib

And there is a third unbuilt version the Ic wich has an retrectable skid for the perfect undersurface.
But more about this another Time in 2013.

Also thank some friends I made in the last years and hook up with me :)

So why not back to basics and build flying triangles.


#4 Knoll53 Sep 29, 2012 06:02 PM

Great bit of history and nice project. That sure is a plump (thick) airfoil ! There were some thick wings back in the 1930's (just yesterday really) but nothing like this. I wonder what those boys were thinking. Certainly there is more to it than just structural strength.



#5 andrecillo76 Sep 30, 2012 01:40 AM

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Thanks Jörg for the introduction :)

Kent: I think the reasons are found easily by posing another question: what happens if you make the airfoil thinner?


#6 Jon Snow Sep 30, 2012 02:24 AM

Andres/Jorg,what sort of lift distribution did the original wing have?I presume the BSLD "evolved" as they developed their designs.
Regards Stuart

#7 Knoll53 Sep 30, 2012 11:46 AM

So this is a revised updated version of the first Horten glider. It looks like a good club glider. In a quick internet search, I could not come up with any pictures of this one. Looking forward to your model. That forward placed main skid should provide for some great smooth landings. Touch and goes at the beach would be easy.

What sort of flight characteristics are you shooting for? Slow thermal? Speed demon slope machine? All rounder sport plane?

At 1:8 scale (1.54m) I would think that it should move out pretty well. At 1:4 scale, it would be quite a sight.

At 2.5m, the Manatee almost draws a crown when I go flying at the local State Park. A real crowd pleaser, although it has no scale detailing.


#8 andrecillo76 Oct 01, 2012 03:11 AM


no idea what distribution they used. There is only an analysis of the H-II in the Horten-Selinger. I do not think that they knew about the bell shaped lift distribution (BSLD) when they desgined and built the H-Ia in the 30's. The triangular shape tends to create a steep bell automatically, though. The Ib changed in shape substantially (less triangular) and I'm sure that the design was new or at least adapted to have a BSLD with less steepness (nearer to sin³) to improve performance.


Originally Posted by Kent
What sort of flight characteristics are you shooting for? Slow thermal? Speed demon slope machine? All rounder sport plane?

Having a predefined shape makes ones life hard to achieve some specific type of characteristic. Anyway, performance is not always the aim - at least not ours. We wanted to have a great scale appearance with good handling properties. Everything else, like good glide ratio is a welcomed plus :D


#9 HortenI Oct 01, 2012 05:08 AM

They got the documents for a parabolic lift distrobution in 1934 from Lippisch (Russ Lee Only The Wing Page 49).


#10 Jon Snow Oct 01, 2012 09:39 AM

Just out of curiosity,have you already modelled the original H1a?
Regards Stuart.

#11 andrecillo76 Oct 02, 2012 01:10 AM

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no we haven't, but it should be no problem. We decided on the Ib/c, because Jörg has plans of the Ic and he's dreaming of building one in full scale ;)

Jörg: I doubt the lift distribution was truly parabolic. Maybe in a specific angle of attack with elevons up. One has to consider trimmed flight conditions, mostly zero pitching moment. If not done, the distribution is purely theoretical and not flyable. I've seen this effect regularly. The high tapered wings makes it almost imposible to shape a sin³ bell into it (see attached figure) for elevons "im strak" and for a trimmed flight condition.


#12 andrecillo76 Oct 19, 2012 12:08 PM

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it's Friday and time to post something about the Ib :D. As always, we start with the wing by glueing the ribs on melamine sheated shelfboards. The spar caps are set into place afterwards and glued. Before fixing the innermost rib, we use the pre assambled center section to align it correctly.

@Kent: So any ideas why the airfoils are thick? One easy point: They were seeking for a sort of lifting body already at that time! Thick airfoils reduced the nonlifting wetted area of the cabin. Thin airfoil => more nonlifting drag producing area. Astonishing, as this is the approach being sought after nowadays to reduce drag. There is at least one other reason...


#13 Knoll53 Oct 19, 2012 12:25 PM

I look forward to seeing the step by step process of your construction method. Although it may be common in Germany, it's not in my neighborhood. I am always trying new techniques and I may have some questions for you along the way.

So far I'm with you.....


#14 Jon Snow Oct 19, 2012 02:50 PM

Possible kit in the future?:rolleyes:
Do you have any info on how they arrived at the airfoils?
Regards Stuart.

#15 marp Oct 20, 2012 02:29 AM

Hello Andrés,

Very nice an interesting project, as usual, I look forward to see the next posts.

I use to work with composite materials but I also like the wood construction, to see your designs evolve is a delight, on the construction side the Horten wings are as "simple" as their name indicates... Nürflugel

Good job.

Miguel Ángel

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