Anders Gidenstamanders at gidenstam dot orgJSBSim model of a Submarine Scout Zero class airship.2007-02-11$Id: Submarine_Scout.xml,v 1.10 2009/04/14 19:33:22 andgi Exp $
NOTE: The center of the bow of the envelope is the origo of
the body coordinate system.
x/y/z = back/right/up
According to [Whale:1919:BA] the horizontal and vertical fins of a
S.S. B.E.2C ship were of the same size and measured 16' by 8'6" and
the rudder/elevators measured 4' by 8'6" each.
The vertical fin of a S.S. Zero might be longer.
Total gas volume vol = 70000 ft^3 = 1982.2 m^3.
Performance numbers from [Whale:1919:BA]:
- Max speed
- S.S. B.E.2C: 40 - 50.5 mph
- S.S. Maurice Farman: "slightly slower"
- S.S. Zero 45 mph
- Endurance
- S.S. Zero: expected 17 hours. Record: 50:55
From [AHT,
http://www.aht.ndirect.co.uk/airships/Technical%20Spec/SSZ%20Airship.htm]:
Envelope capacity 70,000 cubic feet
Ballonets Ballonets (two) capacity 19,600 cubic feet
Length 143 feet 5 inches
Diameter 30 feet
Height 46 feet
Plane area (each) 110 square feet
Car boat-shaped, streamlined,length 17 feet 6 inches
Engine 75 hp Rolls Royce
Propeller Four-bladed 9 feet diameter
Petrol tanks (two) capacity ;120 (UK?) gallons total
Water ballast capacity 26 gallons
Gross lift 2.2 tons
Disposable lift 0.6 tons
Endurance at full speed 17 hours
Top speed 53 mph
Climb 1,200 feet per minute
Turning circle 40 seconds minimum, 230 diameter
65.0 9.1 43.7 25.27 12.15 12.64 12.15 20.0 0.0 0.0 16.1 0.0 -6.4 13.7 0.0 -6.85
According to [VentryKo:1982:AS] the SS Zero class had a useful lift
of 1344lbs (~610kg). Considering that the lift of 1 m^3 hydrogen
approximately is 1 kg that leaves 1370kg of lift for the structure
itself.
300
The empty weight is estimated to consist of:
- The weight of the envelope, guesstimated to 300 kg.
The car and engine will be added as point masses.
% Very rough estimation model of the empty weight CG and inertia tensor.
% Assume the empty weight of is to 100% a cylindrical shell.
m = 300.0 % KG
r = 4.5 % meter
l = 43.7 % meter
% Very rough estimate of center of gravity (based on the inertial estimate):
CGx = 0
CGy = 0
CGz = 0
% Steiners theorem:
% Ixx = \bar{Ixx} + m sqrt(\bar{y}^2 + \bar{z}^2)
% Ixy = \bar{Ixy} + m \bar{x} \bar{y}
% Very rough estimation model of Ixx, Iyy and Izz relative the CG.
Ixx = m * r^2
Iyy = 1/2*m * r^2 + 1/12*m*l^2
Izz = 1/2*m * r^2 + 1/12*m*l^2
Ixy = 0
Ixz = 0
Iyz = 0
6075.0 50780.0 50780.0 0.0 0.0 0.0 21.850 0.000 0.000
Ballast for a S.S. b.E.2C according to [Whale:1919:BA]:
- Water ballast tank
- Located immediatly behind pilot
- Capacity 14 gallons.
17.22 0.0 -7.20 500 0.0 0.0 -1.0 70 43.7 0.0 -1.0 70
According to [VentryKo:1982:AS] page 44 these ships normally carried
two 65lb bombs set as depth charges.
65.0 17.00 -0.57 -7.35 65.0 17.00 0.57 -7.35
According to [Whale:1919:BA] the engine of a S.S. B.E.2C
(also 75h.p. but air cooled) weighed 438lb.
According to [VentryKo:1982:AS] the engine was a 75h.p.
Rolls Royce engine.
Guesstimated weight: 250 kg.
250.0 18.555 0.0 -5.90 85.0 14.9 0.0 -6.85 85.0 16.17 0.0 -6.85 85.0 17.22 0.0 -6.85 400.0 16.72 0.0 -7.20
NOTE: The cell is placed based on the envelope centroid location
as computed by BRLCAD.
Envelope and gas control for a S.S. b.E.2C according to [Whale:1919:BA]:
- Ripping panel at the top of the envelope towards the front
- 14'5" by 8'
- Nose stiffeners: 24
- 2 Ballonets
- capacity 6,375 feet^3 each
- automatic spring valves set to open at 25 - 28mm (of water I presume)
- 2 gas valves one at the bottom and one at the top of the envelope
- Bottom valve automatically opens at 30 - 35mm pressure.
- Top valve is manual only
(")
Envelope and ballonet volumes according to [Mowthrope:1998:Battlebags]:
- Envelope 70,000 feet^3
- 2 Ballonets 9,800 feet^3 each
ballonets/in-flow-ft3ps[0]ballonets/in-flow-ft3ps[1] 18.8 0.0 0.0 22.86 4.55 4.55 340.0 0.0075 0.90 11186.0 0.05 atmosphere/T-R buoyant_forces/gas-cell/temp-R 0.1714e-8 0.2 11186.0 atmosphere/T-R 4.0 buoyant_forces/gas-cell/temp-R 4.0 8.8 0.0 -3.1 6.45 3.00 2.23 255.0 0.01 0.5 5916.06 0.05 buoyant_forces/gas-cell/temp-R buoyant_forces/gas-cell/ballonet[0]/temp-R 0.1714e-8 0.2 5916.06 buoyant_forces/gas-cell/temp-R 4.0 buoyant_forces/gas-cell/ballonet[0]/temp-R 4.0 ballonets/in-flow-ft3ps[0] 34.0 0.0 -2.0 7.55 2.85 2.00 250.0 0.01 0.5 6557.48 0.05 buoyant_forces/gas-cell/temp-R buoyant_forces/gas-cell/ballonet[1]/temp-R 0.1714e-8 0.2 6557.48 buoyant_forces/gas-cell/temp-R 4.0 buoyant_forces/gas-cell/ballonet[1]/temp-R 4.0 ballonets/in-flow-ft3ps[1] 14.7 0.0 -8.2 1.0 2.0 0.8 50000 10000 0.0 NONE 0 16.6 0.0 -8.2 1.0 2.0 0.8 50000 10000 0.0 NONE 0 18.4 0.0 -8.2 1.0 2.0 0.8 50000 10000 0.0 NONE 0 0.0 0.0 0.0 0.2 0.2 0.2 100000 20000 0.0 NONE 0 43.7 0.0 0.0 0.2 0.2 0.2 100000 20000 0.0 NONE 0 35.6 0.0 -5.6 0.2 0.2 0.2 100000 20000 0.0 NONE 0 13.7 0.0 -6.85 0.5 0.5 0.5 25000 10000 0.0 NONE 0
Propulsion installation information for S.S. Zero from [Whale:1919:BA]:
- Water-cooled Rolls Royce
- 75hp
- 4 bladed pusher propeller.
- 9 foot diameter according to [AHT, www.aht.ndirect.co.uk].
- Weight? S.S. B.E.2C: 438 lb.
- Petrol tanks.
- "The petrol is carried in aluminium tanks slung
on the axis of the envelope, identically with the system in use
on the S.S.P's."
What axis? Photos indicate one on each side of the envelope
roughly above the engine.
- Capacity? S.S. B.E.2C: 60 (UK?) gallons.
- 2 tanks. Total capacity 120 (UK?) gallons [AHT, www.aht.ndirect.co.uk].
- 2, 4 or 6 tanks for S.S.Zero [Mowthrope:1998:Battlebags] (a 60 gal UK?)
According to [VentryKo:1982:AS] the engine was a 75h.p.
Rolls Royce engine.
19.2 0.0 -6.0 0.0 0 0 01 19.2 0.0 -6.0 0.0 0.0 0.0 17.26 -4.50 0.0 196.39 196.39 17.26 4.50 0.0 196.39 196.39
Instrumentation for a S.S. b.E.2C according to [Whale:1919:BA]:
Pilot:
- watch
- air-speed indicator graduated in knots
- aneroid (pressure altimeter?) reading to 10,000 feet.
- Elliot revolution counter (tachometer?)
- Clift inclinometer reading up to 20 degrees depression or elevation.
- map case
- oil pressure gauge
- petrol pressure gauge
- glass petrol level
- two concentric glass pressure gauges for gas pressure
- Compass mounted on a small wooden pedestal in front of the pilot.
- Controls:
- rudder pedals
- elevator wheel mounted in a fore-aft direction across the seat (?)
- Valve cord to top gas valve
- Valve cords to the ballonet valves(?)
- Rip cord
Observer/Wireless operator:
- radio w. range up to 50-60 miles.
- Lewis machine gun
buoyant_forces/gas-cell/pressure-psf atmosphere/P-psf buoyant_forces/gas-cell/pressure-psf atmosphere/P-psf
The real aircraft did not have any autopilot. This autopilot is
mostly intended for scripted flights in JSBSim/standalone.
The autopilot is only minimally tuned.
"Two ballonets are provided, one forward and one aft, the capacity
of each being 6,375 cubic feet. The supply of air for filling
these is taken from the propeller draught by a slanting aluminium
tube to the underside of the envelope, where it meets a
longitudinal fabric hose which connects the two ballonet air
inlets. Non-return fabric valves known as crab-pots are fitted in
this fabric hose on either side of their junction with the air
scoop. Two automatic air valves are fitted to the underside of the
envelope, one for each ballonet. The air pressure tends to open
the valve instead of keeping it shut and to counteract this the
spring of the valve is inside the envelope. The springs are set to
open at a pressure of 25 to 28 mm." [Whale:1919:BA] on the S.S.B.E. 2C.
"The valve cords are led to the pilot's seat through eyes attached
to the envelope." [Whale:1919:BA] on the S.S.B.E. 2C.
"Two gas valves are also fitted, one on the top of the envelope,
the other at the bottom. The bottom gas valve spring is set to
open at 30 to 35 mm. pressure, the top valve is hand controlled
only." [Whale:1919:BA] on the S.S.B.E. 2C.
"One ripping panel is fitted, which is situated on the top of the
envelope towards the nose. It has a length of 14 feet 5 inches and
a breadth of about 8 inches." [Whale:1919:BA] on the S.S.B.E. 2C.
The slip stream pressure calculation does not take the direction of the
relative wind into account.
fcs/gas-valve-cmd-norm[0]fcs/ballonet-valve-cmd-norm[0]fcs/ballonet-valve-cmd-norm[1]fcs/rip-cord-cmd-norm
fcs/ripped-sample-hold GE 1.0
fcs/gas-valve-cmd-normap/gas-valve-cmd-norm100.0fcs/ripped-sample-holdatmosphere/P-psfaero/qbar-psfpropulsion/engine/thrust-lbs63.6220.00.0ballonets/slip-stream-pressure-psfbuoyant_forces/gas-cell/ballonet[0]/pressure-psf20.00.0ballonets/slip-stream-pressure-psfbuoyant_forces/gas-cell/ballonet[1]/pressure-psffcs/ballonet-valve-cmd-norm[0]ap/ballonet-valve-cmd-norm[0]fcs/ballonet-valve-cmd-norm[1]ap/ballonet-valve-cmd-norm[1]
fcs/elevator-cmd-norm
fcs/pitch-trim-cmd-norm
ap/elevator-cmd-norm
-11
fcs/pitch-trim-sum
0.5236-11-0.52360.5236
fcs/elevator-pos-rad
1.9099-0.52360.5236-11
fcs/rudder-cmd-norm
fcs/yaw-trim-cmd-norm
ap/rudder-cmd-norm
-11
fcs/yaw-trim-sum
0.5236-11-0.52360.5236
fcs/rudder-pos-rad
1.9099-0.52360.5236-11fcs/static-trim-cmd-norm
fcs/static-trim-cmd-norm
01
-fcs/static-trim-norm
101
fcs/inverse-static-trim-norm
010320
fcs/static-trim-norm
010320
buoyant_forces/gas-cell[0]/buoyancy-lbs
-inertia/weight-lbs
20.0 0.0 0.0 1.0 0.0 0.0 20.0 0.0 0.0 0.0 1.0 0.0 20.0 0.0 0.0 0.0 0.0 1.0 20.0 0.0 -0.3048 1.0 0.0 0.0 20.0 0.0 0.3048 1.0 0.0 0.0 20.0 -0.3048 0.0 1.0 0.0 0.0 20.0 0.3048 0.0 1.0 0.0 0.0 aero/constants/length-ft aero/constants/diameter-ft aero/constants/length-diameter-ft2 aero/constants/volume-ft3 aero/constants/volume-ft3_2_3 aero/constants/added-mass/k-axial aero/constants/added-mass/k-traverse aero/constants/added-mass/k-rotational aero/constants/added-mass/tweak-factor 1.00 0.017453293 aero/alpha-rad 57.29578 aero/envelope-alpha-rad aero/envelope-alpha-rad aero/beta-rad aero/envelope-alpha-rad aero/beta-rad aero/envelope-alpha-rad aero/tmp/wy 2.0 aero/tmp/wz 2.00.50.0 aero/tmp/wx 57.29578 aero/envelope-aoa-mag-rad Total_lift_force_from_envelope_due_to_aoaaero/qbar-psfaero/constants/volume-ft3_2_3