German V/STOL transport/passenger projects

[fightingirish]

Here a nice video about the Dornier Do 31, but no new information so far.

https://youtu.be/FM-OOo4Sw-o

 

[fightingirish]

Similar pictures, mostly posted before, but this time from the source Interavia 1/1970 p.51f.

https://twitter.com/x/status/1267087983448129538

View: https://twitter.com/BurkhardDomke/status/1267087983448129538

https://twitter.com/x/status/1267088623607918592

View: https://twitter.com/BurkhardDomke/status/1267088623607918592

 

[hesham]

From AW 1966.

 

[hesham]

Amazing find by my dear Richard,

but we know HFB.570,what was HFB.560 ?.

https://www.fzt.haw-hamburg.de/pers/Scholz/dglr/hh/text_2018_09_27_FlugzeugbauInHamburg.pdf

 

[Grey Havoc]

Apologies in advance for my very rusty German:
HFB-Projects after 1952

• 1967: HFB 560. Transport airplane with Lift/Cruisefan-system. Project study.

I should note that that particular word (Transportflugzeug) usually means military transport aircraft by default, though sometimes you may see the word 'militärischer' (or less commonly but more accurately "Militär-" i.e. Militär-Transportflugzeug) added to try to differentiate military from 'civilian' heavy airlifters.

 

[hesham]

From Aviation magazine 1972.

 

[hesham]

From JAWA 1972.

 

[td_07]

From JAWA 1972.

I keep seeing the diagrams of the Do 231M, but I still don't get how the rear cargo door won't clash with the aft series of lift fans???

 

[GTX]

Book I recommend if you are interested int his subject:

 

[Jemiba]

From JAWA 1972.

I keep seeing the diagrams of the Do 231M, but I still don't get how the rear cargo door won't clash with the aft series of lift fans???

Good question, but if use the installation in the nose to determine the heightof the lift fans, there would have been
enough room under them in the tail, I think. Of course, those clamshell doors would have had to be fitted with kind
of split ducts.

 

[Maveric]

Book I recommend if you are interested int his subject:

The DoP.333 is new for me...

 

[td_07]

From JAWA 1972.

I keep seeing the diagrams of the Do 231M, but I still don't get how the rear cargo door won't clash with the aft series of lift fans???

Good question, but if use the installation in the nose to determine the heightof the lift fans, there would have been
enough room under them in the tail, I think. Of course, those clamshell doors would have had to be fitted with kind
of split ducts.
View attachment 684090

Wouldn't this mean split ducts would only be able to work if the doors are closed though

 

[publiusr]

Anyone try curled fanblades...that flow around the central shaft-so all you need is to open vents on the bottom of the nacelle housings for thrust-paddlewheel style?

 

[hesham]

From JAWA 1972.

I keep seeing the diagrams of the Do 231M, but I still don't get how the rear cargo door won't clash with the aft series of lift fans???

Good question, but if use the installation in the nose to determine the heightof the lift fans, there would have been
enough room under them in the tail, I think. Of course, those clamshell doors would have had to be fitted with kind
of split ducts.
View attachment 684090

Wouldn't this mean split ducts would only be able to work if the doors are closed though

I think, yes.

 

[Voltzz]

Found a nice image of the Do31 internals with a focus on its flight control systems

 

[hendryojose]

Three-view drawing of Dornier Do 31.

Source: http://aviation-militaire.kazeo.com/Avions-allemands/Dornier-Do-31,a1746673.html

Is there a text in a magazine or website that explains this exact model in the photo of the 31 dornier instead of the E1 prototype?

 

[Dick]

I love how, 50-60 years ago, everyone's solution for vtol was to just put more engines on a frame.

 

[Voltzz]

I love how, 50-60 years ago, everyone's solution for vtol was to just put more engines on a frame.

At Dornier the development of the Do 31 was preceded by the Do 29 with an imo far more interesting tilt-rotor design. However concepts like this were unsuccessful because of the limitation of the flight-control systems of the time. Using different engines for hover and forward flight makes this significantly easier.
With todays digital fly-by-wire we have options that simply werent realizable back then.

 

[Dick]

At Dornier the development of the Do 31 was preceded by the Do 29 with an imo far more interesting tilt-rotor design. However concepts like this were unsuccessful because of the limitation of the flight-control systems of the time. Using different engines for hover and forward flight makes this significantly easier.
With todays digital fly-by-wire we have options that simply werent realizable back then.

Oh I'm very familiar with the designs. I specialized in this field in university. To this day I'm asked "what's the easiest/cheapest way to make a vtol airplane?" And I always answer "If you want a vtol airplane just add lift engines. There is no solution that is easer and cheaper than that. However, you will pay huge penalties in doing so."

Limitations of control systems weren't a primary factor, more so a secondary one. Remember, the unit which became the Pegasus engine was developed before the Do 31. Pegasus was started in 1956, Dornier didn't start on vtol transports until '59. What became Hawkers P.1179 project showed you could slave the hover control system to the engine control system using two or more engines. The lift engine solution was used to add thrust. Get more weight off the ground. With the lowest amount of development cost.

A single engine, or two engines together/four engines together with that kind of output for vtol and then seriously spooled down for forward flight would have huge thermodynamic problems. I spoke to former engineers from McDonnell Douglas. They said there were always propositions to make a supersonic version of Pegasus and none of them went past the initial proposal. Fuel consumption was constantly an issue. Didn't matter if it was subsonic lift, subsonic cruise or supersonic, the engine would almost always be operating off it's design parameters. Simplest way to get around this IS to have separate engines operating in their designated parameters. Otherwise you would have to design a complex multicycle/combine cycle engine which can do all of it. At the time the amount of money required to do so would not have justified the design program. Paper studies were put forward to study the math but that was all.

At the time the only workable solution for such a thing was the tip-turbine lift fan. Ryan XV-5a Vertifan. I seriously looked into that research. Most lift engines ever designed were turbojets not turbofans. The work on Conway and the tip driven Lift fans showed designers that high bypass engines were the way to go when it came to transports. That kind of output would lower the take off run and could be used on civilian/military projects which weren't meant to be vtol. Therefore, multicycle/combined cycle engines were dropped until picked up again by Yakovlev for it's supersonic vtol project and later JSF.

 

[td_07]

Oh I'm very familiar with the designs. I specialized in this field in university.

Any chance you could helping out with this earlier thread? I'm still rather perplexed by the Do 231M's rear lift fans...

Wouldn't this mean split ducts would only be able to work if the doors are closed though

 

[Dick]

Any chance you could helping out with this earlier thread? I'm still rather perplexed by the Do 231M's rear lift fans...

How Dornier's engineers intended to put a rear loading ramp is anyone's guess. All I know about that particular design is that it was intended to have a rear door. Unless they were to extend the lift fans behind the tail, protruding aft from the fuselage, I don't see where the loading ramp would even be connected.
Sorry I couldn't be of more help.

 

[td_07]

How Dornier's engineers intended to put a rear loading ramp is anyone's guess. All I know about that particular design is that it was intended to have a rear door. Unless they were to extend the lift fans behind the tail, protruding aft from the fuselage, I don't see where the loading ramp would even be connected.
Sorry I couldn't be of more help.

Ah oh well, thanks for trying nonetheless!

 

[hesham]

From Air Pictorial 1964.

 

[hesham]

By the way,Dornier had many projects,based on Do.31,more than which have been displayed here,one
of them has a Delta-Wing.

 

[Dick]

By the way,Dornier had many projects,based on Do.31,more than which have been displayed here,one
of them has a Delta-Wing.

A delta wing transport? Do you have a picture of it?

 

[hesham]

A delta wing transport? Do you have a picture of it?

It's a classified materials.

 

[Dick]

It's a classified materials.

How do you know it exists?

 

[hesham]

From this report.

 

[uk 75]

HS had a delta wing vstol airliner in its range of drawings for what became HS141. They had worked on the DH129 which looked like the Do 31 See threads on both.

 

[hesham]

From Interavia 1970.