eages proceedings - hanno fischer 3

Flight Testing of the HoverwingPrepared for the EAGES 2001 International Ground Effect Symposium

Toulouse, France

June 2001

Hanno Fischer

Fischer - Flugmechanik

Kickenstraße 88

47877 Willich / Germany

195

Flight Testing of the Hoverwing

Hanno Fischer

ABSTRACT

The second generation of Lippisch ground effect configuration is currently under developmentat Fischer Flukmechanik. The development of a full size prototype, the 2-seater HW-2VT provedthe concept of the Hoverwing technology to be an efficient and economically viable solution fortake-off.

In this paper are presented the requirements for the Hoverwing 80-seater from the Germanauthorities as well as some of the results and methods that permitted the validation of the concept.

ABOUT THE AUTHOR

Ing.Hanno Fischer was the Technical Director to Rhein- Flugzeugbau GmbH (RFB)in Germany.He has developed around 12 different aircraft like Fantrainer, Fanliner, RW 3 and the military usedWIGs X113, X114 and X114 H (X114 with hydrofoils) .They were designed as aircraft to fulfil themilitary requirement with free flight capability. The concepts were based on the works of Dr.Lippisch.

After retiring from RFB he founded the company Fischer - Flugmechanik together with hispartner Klaus Matjasic. Their target is to develop the ground effect technology towards commercialapplication.

Based on their patents, they successfully designed the first generation of WIGs for civil use-the Airfisch 1, to Airfish 3, for which they granted a production licence to RFB.

In order to achieve a higher economical efficiency, they have developed the Hoverwing techno-logy, which can be considered to be a basis for the second generation of WIGs. Their works aregovernment sponsored from the German Ministry of R&D.

Last design is the Airfisch 8 called now Flightship 8, a 8 seater which has made the maidenflight in February 2001 and is delivered to Australia after successful flight demonstration.Author of many articles and papers in the field of ground effects, for instance in Australia 1996.

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Hanno Fischer Flight testing of the hoverwing 199

200 EAGES Proceedings

Base of Experience in Wing in Ground Effect Craft

Manned Aircrafts

X-113 Single seat military test craft 390 kg

X-114 Six seated military test craft 1800 kg

X-114 H Take-off aid with Hydrofoils 1800 kg

Manned Boats

Airfish 1 Single seat airfoil boat 390 kg

Airfish 2 Modified airfoilboat 600 kg

Airfish 3 A Two seats airfoilboat 760 kg

Airfish 3 PA Power Augmented 950 kg

Airfish 8 (Flightship 8) 8 seats 4310 kg

Hoverwing 2 VT 2 seats 1150 kg

Model Testing

Wind Tunnel Tow Tank

Radio Controlled Free Flight Circular Control Line

Lippisch Airfoil Boats Airfish Variants

Tandem Airfoil Boats Hydrofoils

Static Air Cushion Hoverwing Technology

Theoretical and Experimental Research

DFVLR Gotingen / Braunschweig

Institut Luft- und Raumfahrt University Aachen

Vesuchsanstalt fur Binnenschiffbau VBD


Demonstrator Hoverwing 20/3

Weight

Empty Weight 6534 kg

20 Passengers + 20 kg Baggage 2000 kg

Useful load 2460 kg

Take-off weight 8994 kg

Dimensions

Length 20.98 m

Width 20.00 m

Height 4.94 m

Cabin Length 6.20 m

Cabin Height 1.8 m

Cabin Width 5.0 m

Performance

Range (no Reserves) 500 km

Endurance 3h

Cruise Speed 175 km/h

Cruise Height ≤ 1.75 m

Take-off Speed 126 km/h

L/D 18

Cruise Power 465 PS

Figure 4 : Hoverwing 20


Characteristics of Airfoil Boats

Automatic Height Stability

”Hands-off” Cruise

No pilots licence or pilots experience

Jump Capability

High Manoeuvrability

Short Turn Radius

Short Landing Distance

Flaring over Ice, Snow, Sump

Compact Dimensions vs. Aircrafts

Lower inspections costs than Aircrafts

Capsize Proof

No Sea Sickness

High Comfort due to Boat-like Volume

Limitation of Take-off and Landing (Sea state vs. Scale)

Figure 7 : Hoverwing 80


Preliminary Results of the Comparing Tests with Hoverwing VT

Recommended

by Test Scaled

Performance Results to RESULTS

Specification HW-80

Scale 1 : 1 1 : 3.35 1 : 1

FLARE MODE

Inherently yaw stable 0 0 0 proven

Inherently height stable

up to : 3.5m 1.5m 5.0m proven

Inherently height stable

up to : b/2 b/4 b/4 pending

Radius for 90 degrees turn ≤ 1000m 280m 938m proven

TAKE-OFF

AND LANDING

Take-off distances ≤ 1500m 430m 1440m proven

Take-off at wave height 1.5m 0.55m 1.85m significant

better

Landing at wave height 1.5m 0.6m 2.1m significant

better

Landing at wave height 2.5m often often pending

Stop distance from cruise ≤ 1000m 200m 670m significant

better

Emergency stop distance 400m 120m 402m almost

proven

ECONOMICAL TEST

RESULTS

Glide Ratio 12 13 13 proven

Speed 180km/h 110km/h 200km/h significant

better

Installed Power kW/to 150 59.2 118 proven

Fuel Consumptiongr

PAX.km40 cruise 37 proven

30.3 kW

MISCELLANEOUS

Maximum Take-off Weight 30 214kg 1 065kg 40 040kg significant

better

Maneuvering

in displacement under wind 0 0 0 failed

Weight to Thrust Ratio - 6.4 6.4


Results of the Sea Trials with Hoverwing 2-VT

1999 - 56 take-offs 6h29min flight time 725km flown

TOTAL - 127 take-off 24h36min flight time 2700km flown

MTOW 1 180kg Useful load : 310kg

(Max. Take-Off Weight) (2 seats and ballast)

CG Range 2.777mm ↔ 3.218mm =12 % chord

Take-off time Single seated 24sec

2 seated 43sec

Reduction of Lateral area improved manoeuvrability

Turn Radius diametre : 600m

Obstacle avoidance with 50 m at 125km/h

from 170m

Take-off Power 85kW Minimum : 38kW

Maximum Speed 135km/h

Cruising Speed 110 km/h at 53kW

Minimum Speed 95km/h at MTOW

Height up to 1.9m constant

Hands-up More than 4 minutes at constant height

Testing in Landing with Tailwind

Dangerous Situations 1m wave height

No Structural damages


HW-80 Dynamic testing

Jump

Figure 9 : RPM

Figure 10 : Speed

Figure 11 : Height

Figure 12 : Angle of attack

Figure 13 : Elevator


Landing

Figure 14 : RPM

Figure 15 : Speed

Figure 16 : Height

Figure 17 : Angle of attack

Figure 18 : Elevator


DISCUSSION

Mario Mihalina (MM), Euroavia Zagreb

I have a question about emergency again. Imagine that your craft has to make a jump. What canhappen is that the craft rolls to much and crashes during the jump.

Hanno Fischer (HF), Fischer Flugmechanik

You are right if the craft makes the jump with a high angle of attack because then you take therisk that one of the wing can stall and then what you described happens. But with the direct liftcontrol system that we have, the craft maintains at a constant pitch angle, we do not have the riskof any stall. Anyway our aspect ratio is quite small and for airplanes it is known that the risk youdescribe is larger when the aspect ratio is bigger. So I would say that the risk is really limited.

Chairman Allan Bonnet (AB), SUPAERO

Another question following this question. You make a jump over a boat but you discover thatbehind this boat there is a second one. Can you make several jumps ?

HF

Not too many ! But you have the chance to make a turn. Jumping is not something that you doregularly. This is a chance to minimize the chance of collision.

Graham Taylor (GT), Independent Consultant

First of all, Mr Fischer, let me say very great thanks for presenting an excellent presentation thatbrings together theory and practice. I would like to make a few comments related to my flyingexperiments with models. Your direct lift control is very difficult to achieve on anything else thana Lippisch layout because for example on an ekranoplan layout like I use in my models, the onlyplace where you can use a flap is at the trailing edge and doing so, you change the pitch angle forany use of this flap.

HF

With your configuration, with a flap on the rear, if you deflect a flap, you will change the momentof the wing and the lift distribution. On our craft, we have a forward swept wing and the liftingline is at 50% between the trailing edges of the inner airfoil and the outer airfoil so we have abalance of the flap effect. It can work only with this kind of forward swept wings.

GT

That was exactly the point that I wanted to mention. I do not know if you remember but Itried something equivalent on one of my models, the Mk 6 which I showed a picture of in mypresentation1. The holes would serve to mimic your system. . .but I do not expect it to work as wellas half of your own.

1Page 153, Figure 13. The Editor

eages proceedings - hanno fischer 3

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