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German VTOL Business Jet

Michel Van

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I need your Advice

I working on Story were German history goes little different
Here goes Aerospace industry in VTOL with Do-31 and EWR VJ 101 get into service.
One of civilian application is a VTOL Business Jet

I took the MBB HFB 320 Jet as template
With Mass 9600 kg it need around 117,67kN thrust for vertical take off and landing.
Divided in eight engines each with around 14,7kN (for engine-out backup)
The HFB 320 is ideal since the wings have a negative sweep of 15 °
putting the lift engines on wingtips near centre of gravity fuselage

but there question:
would a shoulder wing work better as low wing of original HFB 320 ?
who improve visibility for Crew downwards ?
and would be control improvement to install a system of reaction control valves directing jets of bleed air from the lift or main engine ?
 

Michel Van

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How the Design looks like
 

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AeroFranz

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High wing for a VTOL seems like a safer bet... i suspect there's all sorts of nasty in ground effects that rear their ugly head once you get closer to the ground (see Bell X-14)
As for hover control, all depends on how much moment arm and force those lift fans can spare. But i guess copying prototypes of the 60s is not a bad starting point. Actually determining if you need them or not brings about finding suitable requirements (crosswinds, degraded engine out control, etc.) and requires knowing a lot about the airplane (for example: inertias)
 

Michel Van

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After some calculation
I have payload of only 188 kg
Reducing the Lift engines from 8 to 6
I can increase that to 442 kg

with replace metal parts by composite fiber i could increase the Payload
but it show clearly that why the concept of small VTOL Business Jet never made it and Helicopter fill that role nice

So why here ?
It's faster and better range then Helicopter and for VIP and Superrich a real status symbol...
 

Archibald

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You should tilt the main engines on the rear - it would really help. And the Germans did exactly that on VJ-101 !
 

Michel Van

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You should tilt the main engines on the rear - it would really help. And the Germans did exactly that on VJ-101 !
On that small jet main engine would be a swivel nozzle, a much simple and lest costly better alternative.
looking in Thrust of main engines there similarly to Lift engine around 15kN !

i overlook that, Thanks Archibald for pointing me into right direction
 

riggerrob

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That reminds me of a couple of American proposals. One was to replace Lockheed's S-3 Viking ASW carrier plane. The key difference was large diameter fan jets mounted just forward of the wings. For vertical takeoff, engines pivoted to vertical.

Another, more radical proposal looked like a Cessna Citation with a flat nose. Main engines were mounted just aft of a rearwards swept wing and tilted to vertical for landing and take-off. The nose contained a lift engine that was only used for take-off and landing. I suspect that the nose-mounted engine also served as a auxiliary power unit to cool the cabin before executives boarded.
 

uk 75

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Hawker Siddeley came up with the HS140. It would have made a nice replacement for the Beagle Basset in RAF service.
 

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