The Distributed Open-Rotor Aircraft

SOAR - diStributed Open-rotor AiRcraft• FP7-Transport L0 #341455• Oct. 1, 2013 – Sept. 30, 2015• EU Contribution: €591214

• AAT.2012.6.3-1. - Breakthrough and emerging technologies • AAT.2012.6.3-2. - Radical new concepts for air transport

• Consortium:German Aerospace Center (co-ordinator)von Karman Institute for Fluid DynamicsSaarland UniversityFanWing Ltd.

Early FanWing testing

Open-fan wing study

• USTOL and steady flight already proven in flyingmodels with rotor diameters up to 25 cm

• SOAR project objective is to investigate large open-fan wing with 50 cm diameter rotor� Powered wing model of 1.5 m span tested in wind tunnel� 2D unsteady CFD simulations performed

• Aircraft projected and evaluated for identifiedmarkets

SOAR project workplan• WP1 – Wing model

construction� Model build-up -

FanWing� Drive system –

USAAR

• WP2 – Wind tunneltesting and design optimisation� Includes CFD studies -

VKI

• WP3 – Case studiesand conceptevaluation� Market identification &

concept evaluation –DLR

� +Flight simulation –USAAR

• WP4 & WP5

Wing model build -up

Wind tunnel balance

Wind tunnel testing

Test date 26/08/2014 Configuration:Camber + TER2.5cm + end shroud + cavity holes covered + cavity gap 5.8cm +LED2cm+extrados improved

Test 34 Blade angle:5 degrees With tape on the side Run 1

T=D Zero average

AoA 0 0 0 0 0 0 0 20 20 20 -10 0 -10 0 0

A 0.7963 0.8636 0.9439 1.0650 0.7387 0.8025 0.9014 0.5286 0.5271 0.5562 0.8652 0.7759 0.8682 0.7556 0.7876 0.7919

B 0.5801 0.6517 0.7411 0.8826 0.4990 0.5756 0.6720 0.2916 0.2818 0.3253 0.6090 0.5366 0.5997 0.5040 0.5748 0.5774

C 0.4481 0.3664 0.2613 0.1203 0.4614 0.3711 0.2504 0.6159 0.5769 0.5004 0.3761 0.3979 0.3397 0.3509 0.4532 0.4507

D -0.1127 -0.0755 -0.0324 -0.0055 -0.1377 -0.0978 -0.0505 -0.1988 -0.1979 -0.1767 -0.1142 -0.1119 -0.1125 -0.1119 -0.1093 -0.1110

E 0.4717 0.4232 0.3632 0.2824 0.4258 0.3666 0.2907 0.5762 0.5026 0.4212 0.3420 0.3761 0.2879 0.3012 0.4662 0.4690

U 0 0 0 0 10 10 10 10 10 10 10 10 13 13 0

rpm 0 600 900 1200 600 900 1200 600 900 1200 631 826 865 1098 0

Number of test 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

L 1.9118 -22.4818 -63.1905 -81.7046 -112.8911 -153.2909 -199.5970 -225.0031 -316.1490 -397.7487 -44.9237 -165.8520 -125.5118 -315.7029 -1.9118

D -1.8356 38.5961 85.4099 114.7212 -29.0878 14.3092 65.7406 -95.5110 -94.5570 -71.5080 -3.5010 -1.0405 -1.7160 -1.0133 1.8356

Real rpm 0 599 900 1200 601 900 1200 600 900 1200 631 826 865 1098 0

Torque (N.m) -0.265 10.202 23.550 40.122 6.926 18.306 33.480 1.802 11.743 25.074 10.290 14.517 21.088 27.405 -0.210 -0.2374

Mech power (W) 0.000 654.832 2241.907 5071.708 450.838 1747.671 4237.050 128.137 1129.123 3180.721 695.629 1276.231 1931.707 3178.383 0.000

Elec power (kW) 0 0.72 2.29 5.19 0.54 1.85 4.27 0.28 1.32 3.26 0.84 1.46 2.06 3.28 0

Comments:

G/W Lift 3.433223 2.818607 1.610989 25.04029 8.77115 4.710754 175.5952 6.458 12.99545 6.497456 9.932815

G/W Trust 5.89405 3.809697 2.261984

Vector thrust4466.646 10624.45 14084.25

G/w Vector6.821059 4.739023 2.777023

Pressure and flow data

CFD investigation

• Incoming flow sucked from the leading edge and pumped towards the trailing edge• Creating lower pressure zones for the wing lift• Major portion of the lift generated at the cavity below the fan cage• Suction created by the fan proportional to the fan RPM

Experiment vs. Simulation –Pressure distribution

Discrepancies

• Experiments:� Vortex didn‘t form well� Low suction in cavity� Stagnation point didn‘t

move downward� Rotor load decreased

with increasing airspeed

• � More experiments� Improvement seen but

tests limited in scope

• Simulations:� Vortex formed well� High suction in cavity

(approx. 2.5 timesgreater)

� Stagnation pointmoves down withincreased power

Market study

• Checked ROI on new aircraft programs• Checked willingness to pay premiums for

enhanced low-speed maneuverability• 2500 kg and 10000 kg payload classes

� Agriculture: 4000 units / year, +5% for new aircraft� Firefighting: 30 units / year, +125% for new aircraft

• Existing cargo markets very cost competitive• Can the open-fan wing create new cargo

markets by virtue of its unique flight properties?

Design study

• Crop spraying application chosen• Various design models used to estimate

structure

Operating cost analysis

0.00 € 2,000.00 € 4,000.00 € 6,000.00 € 8,000.00 € 10,000.00 € 12,000.00 €

Baseline (20 flights per month)

SOAR Business Operator:

SOAR (Owner Pilot, 5 flights per month)

SOAR (Owner Pilot, 20 flights per month)

Ownership Fuel Pilot

Flight simulator model

Project summary

• Vortex formation problems in large wing model� Follow-up tests indicated improvement

• CFD simulations showed vortex formation andcorresponding high lift behaviour

• Application markets were identified:� Fire-fighter, crop duster, short-haul freight, civil UAV

• Crop duster aircraft projected� Rough layout proposed� Performance predicted� Flight simulator model generated

Project follow -up

• More extensive experimental campaign neededfor study and optimisation of large open-fan wing

• 3D unsteady CFD simulations proposed

• A manned ultralight aircraft with instrumentationwould enable extensive investigation of real flight behaviour

Please visit our display …www.soar-project.eu