Beagle Pup

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Beagle Pup
Beagle Pup 100.png
Type Light Sport, General Aviation
Author(s) Richard Senior
FDM JSBSim
--aircraft= pup100, pup150, pup160
Status Alpha
 FDM Stars-2.png
 Systems Stars-2.png
 Cockpit Stars-2.png
 Model Stars-2.png

The Beagle 121, better known as the Beagle Pup is a light sport and general aviation aircraft designed and built during the 1960s by Beagle Aircraft Ltd at Shoreham and Rearsby in the United Kingdom.

Variants

Series 1 (Beagle Pup 100)

Powered by a 100hp Rolls-Royce Continental 0-200 engine, the original Beagle Pup has modest climb rates of around 500 ft/min and a cruise speed of just over 100 knots. Fuel capacity 24 imperial gallons (29 US gallons).

Series 2 (Beagle Pup 150)

The Pup 150 retains the same airframe as the Pup 100 with an enlarged and reshaped engine cowl to accommodate a 150hp Lycoming 0-320-A2B engine. The extra power allowed for additional passenger seating in the rear and produced climb rates of around 800 ft/min and a cruise speed of around 115 knots. Fuel tanks were unchanged from the Pup 100, although there was an option for additional tanks to increase the capacity to 34 imperial gallons (41 US gallons).

Series 3 (Beagle Pup 160)

The Pup 160 has exactly the same airframe and cowl as the Pup 150, but was fitted with fuel tanks totalling 34 imperial gallons (41 US gallons) as standard and powered by a 160hp Lycoming 0-320-D2C engine. Cruise speed and climb rates are comparable to the Pup 150, the Pup 160 is really about increased range and carrying capacity.

The most common aircraft currently in use is the Pup 150. Only a handful or Pup 160s were made before Beagle went into liquidation and most were exported from the UK. The Pup 100 is considered to be slightly underpowered.

Flight Notes

The aircraft is still in an alpha state but completely flyable from the 3D cockpit. The external model is currently of a Pup 100 for all three variants.

For a model this new, systems are relatively mature. Startup sequence is modelled ... but no controls in the 3D cockpit. Autostart executes the startup checklists and puts the aircraft in a ready for takeoff state with takeoff flaps set. Some basic cockpit lighting is provided for night flying. Overall, it is quite flyable.

There is a continuous fuel simulation, i.e. it saves the fuel levels on exit. Check fuel before you fly.

Performance has been roughly tuned on the Pup 100 for cruise below 5000ft. The Pup 150/160 fall into the right ballpark of cruise speed but appear overpowered at low altitude. Generally speaking, relieve the weight on the nose by 50kts and use the rudder, rotate at 70kts and flaps up on positive climb. There is a keyboard shortcut to set cruise power, lean the mixture (the EGT major tick scale is 100*F, and typical leaning is 50*F rich of peak). Approach at 70-80kts.

The aircraft has not been tested with any launcher, official or otherwise.

Sperry SP Series Autopilot

WIP.png Work in progress
This article or section will be worked on in the upcoming hours or days.
See history for the latest developments.

The Sperry SP autopilots consisted of a series of modules that could be added individually to an aircraft to provide different degrees of autopilot control. Note the white blanking plates at the bottom of the autopilot controller, which are placeholders for a series of control buttons.

The most basic configuration -- the SP1 -- is simply a yaw stabilizer, controlling only the rudder. The SP2 systems are two-axis autopilots, controlling aileron and elevator. The full set -- designated the SP3 -- is a three-axis autopilot with altitude hold and automatic heading hold. I have seen photographs of later units with a complete set of four buttons on the controller: HDG HLD, ALT HLD, NAV LOC and GLD HLD but I am not aware of Beagle having fitted these to any aircraft.

Sperry SP3 in the Beagle Pup

Judging by photographs, publicity material and existing aircraft, Beagle did not fit an autopilot to the Beagle Pup as standard. During the time the Beagle Pup was being manufactured, they were fitting Sperry SP3 autopilots to the Beagle 206 (Basset). Rather than use the generic Flightgear autopilot, I've taken the opportunity to satisfy my appetite for obscure autopilot controllers by modelling the Sperry SP3 for the Beagle Pup.

The SP3 is a three axis autopilot, controlling pitch, roll and yaw. If you are flying the Beagle Pup with auto-coordination turned on, the autopilot does not attempt to control the rudder, so technically you are flying with a Sperry SP2A and Flightgear is dealing with coordinated turns.

Controls are basic. There is a pitch wheel to control pitch, a turn knob to control roll, an altitude hold button and an on off switch. Trim controls are also provided for the pitch and roll channels. Note that these are not direct controls of aileron or elevator trim, these are autopilot trims. There is no button or switch for heading hold, and no heading bug; heading hold is automatic when a neutral turn is selected. There is no automatic tracking of a VOR radial, no glideslope coupling and the autopilot does not follow a route-manager route.

Control of pitch is fairly self-explanatory. When the autopilot is turned on, it will attempt to stabilize the aircraft at the pitch that is set on the wheel. So if you turn the autopilot on during climb, you will want to preset a positive pitch on the pitch wheel of about 4-5 degrees. With the pitch wheel at zero detent (use the help text in the bottom left corner of the screen) the idea is that the aircraft should fly level. It probably won't, which is why there is an "Elev. Trim" knob. With the aircraft at a typical cruise altitude and power (leaned if necessary), adjust the elev trim knob so that a selection of zero pitch on the main pitch wheel produces level flight. This trim setting is saved when you exit Flightgear but may need adjusting based on fuel and payload. Once the pitch axis is trimmed, with the pitch wheel centered, you can press the "ALT HLD" button to hold the current altitude. Altitude hold is cleared when you rotate the pitch wheel away from center and needs to be pressed again to hold a different level.

Control of roll is also quite simple. As with the pitch channel, trimming may be necessary. The turn knob allows left/right turns up to 20 degrees of bank, which produces a standard rate turn. With the turn knob centered, the aircraft is supposed to fly wings level and, if the heading is stable, will lock onto the stable heading. If you center the turn knob and the aircraft doesn't lock onto the heading, use the roll trim wheel to cancel out any turn due to imbalance of the aircraft. Again, the trim is saved on exit and screen help indicates the amount of turn you have selected and also the heading hold. It takes 3-5 seconds to lock the heading after selecting zero bank.

There are no controls on the controller for the yaw channel. Coordinated turns are handled by the autopilot if auto-coordination is turned off. If you are flying with mouse or keyboard control and the autopilot is controlling yaw, you will want to center the rudder before engaging the autopilot. Currently the only way to do this is by using the HUD.

Without a heading bug, establishing a heading takes a little practice. The key is that the autopilot is tuned to roll level from half the bank angle from your target. So, for example, if you are flying at 270 and you want to fly a heading of 360, establish a full right turn with the turn knob (20 degrees of bank) and, just before 10 degrees from your target, i.e. 350 degrees, center the turn knob. The turn knob uses a standard knob/slider animation, so holding down the shift key and left-clicking banks right in 10 degree increments. Shift middle-click banks left. The controls are heavily filtered to keep these turns smooth. Fine-tuning a heading, e.g. when tracking a NAV radial, is easily achieved by clicking the turn knob a couple of times to bank slightly left, then middle-clicking a couple of times to center again.

Note that Ctrl-z toggles the main autopilot on/off switch. Other conventional autopilot shortcuts, e.g. Ctrl-h, Ctrl-h do not work with this autopilot.

Development Status/Issues/Todo

FDM

Information limited. Aerodynamic knowledge limited. Advice welcomed ;)

Category Description Progress
Weights Refine limits from type certificate Done Done
Balance Position fuel tanks more accurately Done Done
Balance Develop a more accurate estimate of COG Done Done
Control Refine surface position travel 50}% completed
Control Look at flap lift (flaps tend to balloon) 50}% completed
Propulsion Tune engine rpm, mp and hp Pending Pending
Propulsion Adjust performance variation with altitude Pending Pending
Reactions Add contact points and crash detect Done Done
Reactions Fix bouncing at startup 80}% completed

Systems

Category Description Progress
Electrical Research and simulate circuit breaker panel switches Pending Pending
Electrical Add basic current simulation Pending Pending
Icing Add carb temperature simulation 20}% completed
Icing Add pitot heat simulation Pending Pending
Fuel Add fuel pressure simulation Pending Pending
Fuel Refine manifold simulation Pending Pending
Fuel Create refuelling dialog Pending Pending
Fuel Filter EGT for instrument display Done Done
Fuel Model unusable fuel and full quantities Pending Pending
Other Verify pitot/static and suction Pending Pending
Checklists Complete to match POH 30}% completed
Autopilot Heading hold doesn't properly respect gyro precession Done Done

Cockpit

Cockpit is currently a placeholder only, populated with instruments from the Cessna 337.

Category Description Progress
Model Create seats Pending Pending
Model Create and select animate rear seats Pending Pending
Model Model centre pedestal Pending Pending
Model Model panel Pending Pending
Model Model and animate fuel tank selector Pending Pending
Model Reinstate missing window sills Done Done
Instruments Model KR-86 ADF receiver and display Pending Pending
Instruments Model KX-175B comm/nav Pending Pending
Instruments Model and drive Sperry SP3 Autopilot 90}% completed
Instruments Create Transponder Pending Pending
Instruments Legacy DME? Pending Pending
Panel Recreate panel instrument dials - various Pending Pending
Effects Add ALS shadows (cube map) Pending Pending
Effects Create lightmaps for pilot/copilot flood Pending Pending
Effects Add internal glass effects Pending Pending
Sound Switch clicks 80}% completed
Sound Stall warning Pending Pending
Sound Environment sounds (rain, thunder) Done Done

External Model

Category Description Progress
Gear Add fuselage cowls (main gear strut housings) Done Done
Gear Animate main gear compression Pending Pending
Gear Animate wheel rotation Pending Pending
Gear Model oleo strut and animate (review compression and length) Pending Pending
Gear Model main gear brakes and cables Pending Pending
Gear Add or texture tyre treads Pending Pending
Lights Add navigation, strobe and beacon lights Done Done
Lights Add ALS landing and taxi lights Done Done
Model Create 150/160 engine cowl variant Pending Pending
Model Model and texture transparent window glass Done Done
Model Model aerials and fins 70}% completed
Model Model pitot tube Done Done
Model Model and animate control surface hinges Pending Pending
Model Model tie down points Pending Pending
Model Model exhaust and air intake 40}% completed
Model Create paint kit with construction lines Pending Pending
Model Add livery support Done Done
Model Improve ambient occlusion map Pending Pending
MP Verify multiplayer properties Done Done
MP Verify replay Done Done
MP Fix livery over MP Done Done
Sound Improve consistency between 100 and 150/160 40}% completed

External links