German V/STOL transport/passenger projects

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.
 
Last edited:
Book I recommend if you are interested int his subject:

81eVkzl+55L.jpg


91g900w1GYL.jpg
 
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.
1663180488661.png
 
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
 
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?
 
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.
 
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.
 

Attachments

  • Do29(2).jpg
    Do29(2).jpg
    124.9 KB · Views: 67
  • Do29(1).jpg
    Do29(1).jpg
    223.8 KB · Views: 59
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.
 
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
 
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.
 
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!
 
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.
 
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.
 
From Interavia 1970.
 

Attachments

  • 20.png
    20.png
    621.3 KB · Views: 31
  • 21.png
    21.png
    470.6 KB · Views: 33
  • 22.png
    22.png
    2.1 MB · Views: 34
  • 23.png
    23.png
    497 KB · Views: 33
  • 24.png
    24.png
    521.6 KB · Views: 27
  • 25.png
    25.png
    510.7 KB · Views: 27

Similar threads

Please donate to support the forum.

Back
Top Bottom