Soldenhoff Real Aircraft and Projects

[hesham]

Hi,


Soldenhoff began designed an engine in Zurich-Switzerland in 1926,then he switch
to Germany to start his tailless aircraft series,LF 5 was tandem two seat tailless light
aircraft with pusher engine,followed by LF 6,which developed from LF 5 for the flight
across Europe in 1929,remained a project only,after that came the series of tailless
aircraft,the A/3,A/4 and A/5.


In 1930 created anther tailless aircraft but strange design,never pass a Model stage,
he returned to Switzerland in 1932 and submitted a SL-1,a single seat tailless aircraft.


http://flughafenbb.wordpress.com/1919-1945/flugpionier-soldenhoff/

 

[hesham]

Hi,


he also designed the A/6 with control flap wing.

 

[Stargazer]

Soldenhoff is new to me, thanks a lot for sharing.

 

[hesham]

Thank you my dear Stargazer.

 

[hesham]

Hi,


here is the LF 6 project,Luftfahrt 1/1980.

 

[Stargazer]

From Popular Aviation, November 1930:

 

[hesham]

Nice find my dear Skyblazer

 

[hesham]

Hi,


here is some early patents to Soldenhoff.


https://flughafenbb.files.wordpress.com/2015/08/de279895-1912-09-21.pdf
https://flughafenbb.files.wordpress.com/2009/02/de345022.pdf

 

[riggerrob]

His 1912 patent resembles a Rogallo wing.

 

[hesham]

His 1912 patent resembles a Rogallo wing.

That's right Riggerrob,


and this concept was very popular in this days.

 

[hesham]

Hi,

https://books.google.com.eg/books?id=zdcZiA_OUxMC&pg=PA97&dq=soldenhoff+magazine&hl=ar&sa=X&ved=0ahUKEwjV2bOapPjKAhUFRhQKHS5EBcUQ6AEIGjAA#v=onepage&q=soldenhoff%20magazine&f=false

 

[hesham]

From, Die Flugzeuge des Alexander Soldenhoff,

here is some Soldenhoff aircraft,and some unknown or little known
Projects,such as A.15,So.B,So.C & Military 1937.

​

 

[hesham]

And,

 

[hesham]

Also anther Projects;

1928 - a stock corporation is not established. Design of a 5-engine
flying wing airliner.

1931 - Offer to the military department of Bern to develop a training
aircraft, a single-seater fighter and a large transporter.

1935- Single and two-seater Projects.

1937 - Fighter aircraft Project as a tailless arrow biplane.

1945 - Presentation of Soldenhoff's "People's plane" Project by the Zurich
flight cooperative.

 

[hesham]

Military 1937.

Hi,

In July 1937, during the international flight meeting in Dübendorf,
Soldenhoff exhibited two paintings in a Zurich shop window showing
a military aircraft he had designed. He had painted both pictures
especially for the flight meeting in order to make propaganda for
his tailless, inherently stable construction. The pictures have the
numbers S 288a and S 289a in Soldenhoff's works catalog. This
somewhat unusual advertising method was not a success for him.
This "combat aircraft project" was a tailless arrow double-decker.
The two wings were cantilevered and staggered. The lower surface
was arranged at the bottom of the trunk and the upper on a balda-
chin. The nose wheel landing gear could be half retracted. The engine
was at the top of the trailing edge of the upper deck and operated
on a pressure screw. The fuselage carried a machine gun stand at the
front and rear. Shortly behind the front stand was an open cockpit with
two seats next to each other.
Further details are not known. The machine was apparently a further development of the fighter aircraft project from 1931.
After that it was quiet again for a long time around the aircraft designer Soldenhoff. In the years of the Second World War he was mainly
concerned with painting, even if he never completely lost sight of
aviation.

 

[riggerrob]

Those swept, constant-chord wings might have inspired Withold Kasper's 1950s, 1969s and 1970s vintage flying wings. Kasper's control surfaces were similar tip-mounted elevons with hinge-lines perpendicular to the longitudinal axis.
Families of the other team-members - in the "BKB" design team still debate how much Kasper contributed to the sailplane he is most famous for.

 

[klem]

Die Flugzeuge des Alexander Soldenhoff.

 

[hesham]

Die Flugzeuge des Alexander Soldenhoff.

They are in reply # 12.

 

[klem]

Die Flugzeuge des Alexander Soldenhoff.

They are in reply # 12.

Yes I saw the pictures of the reply # 12 dear hesham,you posted beautiful pictures while I posted a pdf,the image is mute without text as much to make benefit the members of SPF by a pdf to read,look at and understand the historical context of the achievements Soldenhoff because a text gives life to the image.Regards

 

[steelpillow]

Die Flugzeuge des Alexander Soldenhoff.

Thank you, this is fascinating.
These designs are closer to the aerodynamics of the successful Dunne "safety" biplanes than most derivatives have been. For example where Dunne avoided reflex trailing edges, GTR Hill and Alexander Lippisch adopted them. But Soldenhoff does not; like Dunne, he relies on washout (twist) for stability and needs fins only to counter the area of the forward fuselage. However unlike Dunne, he tends to decrease camber towards the tips. The 1931 sesquiplane (drawing on page 22) also bears close comparison with Hill's contemporary Pterodactyl fighter.
I shall study this carefully for hints on the flying qualities of these machines!

By the way, I notice that this is Teil 2 (Part 2). Is there by any chance a pdf of Teil 1 available? Are there any more?

 

[klem]

Die Flugzeuge des Alexander Soldenhoff.

Thank you, this is fascinating.
These designs are closer to the aerodynamics of the successful Dunne "safety" biplanes than most derivatives have been. For example where Dunne avoided reflex trailing edges, GTR Hill and Alexander Lippisch adopted them. But Soldenhoff does not; like Dunne, he relies on washout (twist) for stability and needs fins only to counter the area of the forward fuselage. However unlike Dunne, he tends to decrease camber towards the tips. The 1931 sesquiplane (drawing on page 22) also bears close comparison with Hill's contemporary Pterodactyl fighter.
I shall study this carefully for hints on the flying qualities of these machines!

By the way, I notice that this is Teil 2 (Part 2). Is there by any chance a pdf of Teil 1 available? Are there any more?

Die Flugzeuge des Alexander Soldenhoff.Teil 1-Teil 3.

 

[steelpillow]

Die Flugzeuge des Alexander Soldenhoff.Teil 1-Teil 3.

Wunderbar! Ich werde langsam ihnen übersetzen.

I see these are published by the ADL, the Arbeitsgemeinschaft Deutsche Luftfahrthistorik. This leads me to their website, where copies may be found - along with a treasure trove of the weird, wonderful and arcane. Just play with the Dokumentationen + Berichte menu:

Start - Arbeitsgemeinschaft Deutsche Luftfahrthistorik

adl-luftfahrthistorik.de

 

[klem]

Die Flugzeuge des Alexander Soldenhoff.Teil 1-Teil 3.

Wunderbar! Ich werde langsam ihnen übersetzen.

I see these are published by the ADL, the Arbeitsgemeinschaft Deutsche Luftfahrthistorik. This leads me to their website, where copies may be found - along with a treasure trove of the weird, wonderful and arcane. Just play with the Dokumentationen + Berichte menu:

Start - Arbeitsgemeinschaft Deutsche Luftfahrthistorik

adl-luftfahrthistorik.de

Good luck mit der Übersetzung, the sesame opened and here you are in the cave of ADL and don't hesitate to take all the jewels because the forty thieves are around.

 

[steelpillow]

The ADL document is a wonderful, comprehensive and well-illustrated account of Soldenhoff's aeroplanes and ideas by Günter Frost. It is posted in three parts, though as yet I am only half way through Part 1.
I have also been trawling Espacenet for his patents. He took out about half a dozen over his lifetime, some in several countries - three of them in GB.
To translate the opening remarks of the ADL piece fairly freely:

"When the tailless aircraft is discussed in German aviation histories of the 1920s and 1930s, it is mainly associated with names such as Alexander Lippisch or the Horten brothers. Anyone who is especially well versed in aviation history will also be familiar with the experiments of Gottlob Espenlaub.​

"But one name will seldom appear: Alexander Soldenhoff. A native of Switzerland, he began working on tailless swept wing designs in 1909 and received his first patent in 1912. Soldenhoff is given little space in the specialist literature, and often enough even that little is tainted with mistakes."​

Note that 1909 was when Dunne first outed his previously-secret design in a patent and began work on the D.5. Soldenhoff's main preoccupation was the tailless swept wing and he acknowledges the date of a1909 in his first patent (uploaded above here somewhere). Dunne is known to have been much admired in Germany - like many a prophet, far more so than in his own country - and Soldehoff's first, 1912 patent is basically a Dunne-type conical wing with a different alignment of the cone and the outer leading edge cut away to create a bat-like kink in the leading edge. There are hints of the Zanonia principle in his next, 1918 patent, a principle which Dunne so disparaged.
In 1928 he contacted Fairey Aviation in the UK to drum up finance for his latest incarnation. By then he had several patents elaborating on this and related ideas. Fairey declined to get involved. I suspect that he wrote to them because of Dick Fairey's well-known association with Dunne's pioneer Syndicate. His patents are all rather weird, with oddball aerodynamic features justified primarily with handwaving about their benefits. For example a series of steps in the underside of the wing, reminiscent of those under the hull of a flying boat, are claimed to confer stability and reduced drag. He was decidedly non-technical, being, like Hose Weiss in Britain, an artist by trade. Reading them, it is hard not to gain the impression that he was just a crank. I am not surprised Fairey's declined.
But then again, judging by the technical material unearthed by Frost, there may have been something to at least some of his ideas. I am thoroughly enjoying the read, or is that the ride?

 

[klem]

"But one name will seldom appear: Alexander Soldenhoff. A native of Switzerland, he began working on tailless swept wing designs in 1909 and received his first patent in 1912. Soldenhoff is given little space in the specialist literature, and often enough even that little is tainted with mistakes."​

Es stimmt dass many names having contributed to history did not have their place on the podium or at least the adequate merit but I think that at this beginning of the century of aviation certain aerodynamic visions did not correspond to current ideas received. This is perhaps why Soldenhoff imperceptibly slipped behind the scenes of history. From Dunne to Soldenhoff via Lippisch and Horten, the perspective schemes have not changed greatly because the unalterable established bases are there as raw material; the rest is only a refinement of the projected structures.

 

[steelpillow]

Frost's account reveals more parallels with Dunne besides his tailless swept "safety plane" theme.
Soldenhoff was almost the same age as Dunne and was bitten by the aeronautics bug just a few years later. He picked up on Dunne’s tailless swept safety plane as early as 1909 and developed his own variations on the theme. He too struggled with finance and continually had to find fresh input to his syndicate.
Having failed to interest Fairey’s company, the next year he brought his untried prototype LF 5 to England and exhibited at the Olympia Aero Show in a carbon copy of the D.7 showing. Sadly, neither orders nor funding were forthcoming. Then in 1931 he wrote about his progress for the respected German journal Flugsport. It caught the eye of one M’lle de la Meurthe, still a major shareholder in what was now Nieuport-Delage. She opened negotiations for her company to buy up his French rights, as her predecessor had with Dunne. Unfortunately Soldenhoff’s own struggling syndicate was becoming embroiled in suicidal internal squabbles and no deal could be struck. Despite this, Nieuport-Delage continued to repeat history and displayed their own look-alike prototype NiD 941 at the 1932 Paris Salon. However, unlike their Dunne copy, this one was not licensed and we know that it did eventually fly, but then soon sank without trace.

 

[steelpillow]

In his Conclusions, Frost quotes a paragraph from Swiss aviation historian Erich Tilgenkamp, which I translate here:

With unstinting effort the artist taught himself the subject of aircraft construction and, based on his tireless work, intuitively arrived at results which astonished every expert. That his discoveries enabled significant improvements in relation to the stability and other properties of small aircraft, was sufficiently confirmed by [wind tunnel] measurements at the Aerodynamic Research Institute in Göttingen. Unfortunately everything; the preparatory work, the models and even the calculations, lacked any scientific foundation. Indeed the means to work through the artist's ideas scientifically from the ground up were lacking.

He adds that the combination of the technical challenge of tailless flight, together with the economic crisis of the Great Depression, combined to kill off Soldenhoff's hopes.

I would agree with all of that, but I would add my bit too: that a picture of organisational, managerial, financial and technical incompetence also shines through. After his first crash, due to undercarriage collapse, the DVL insisted on inspecting every design before it flew. He employed a couple of mechanical designers but, despite the best efforts of the team and the DVL, plane after plane suffered the same undercarriage collapse. The So A/3 flew well but subsequent models were never as aerodynamically acceptable; Soldenhoff's intuition let him down on more things than it brought light to. And it didn't help that his investment syndicate responded to the cash shortage by setting up rival manufacturing companies and self-destructing in a flurry of (to some extent justifiable) legal writs.

A shame, as there must have been good ideas in there for the Göttingen studies to have been so positive, along with a good many pilot's reports. But we may never know what they were.

 

[steelpillow]

Second half of this short video shows the LF 5 taking off and flying. Note the characteristic ignorance of the modern commentator.

View: https://www.youtube.com/watch?v=ICjsalZj7qc

 

[hesham]

So weird,

I felt that,some sites speak about them as a real designs for him,here;

https://www.secretprojects.co.uk/threads/soldenhoff-dream-for-large-aircraft.10562/

 

[hesham]

What was type B ?.

Sanger

Designs made by Sanger rocketplane

histaviation.com

 

[riggerrob]

Second half of this short video shows the LF 5 taking off and flying. Note the characteristic ignorance of the modern commentator.

View: https://www.youtube.com/watch?v=ICjsalZj7qc

A better understanding of aerodynamics would have taught him that swept wings are naturally stable in yaw.
Swept wings are also stable in roll, to the point that many military cargo planes with high-mounted swept back wings even have negative dihedral to reduce (too stable) Dutch roll.