Aircraft

Self launching glider packs a retractable jet engine

Self launching glider packs a ...
A low pass of the BonusJet (Image: Bill Pearson)
A low pass of the BonusJet (Image: Bill Pearson)
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BonusJet front view (Image: Mark Mocho)
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BonusJet front view (Image: Mark Mocho)
A low pass of the BonusJet (Image: Bill Pearson)
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A low pass of the BonusJet (Image: Bill Pearson)
BonusJet takes to the skies (Image: Bill Pearson)
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BonusJet takes to the skies (Image: Bill Pearson)
BonusJet prepares for its first flight (Image: Mark Mocho)
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BonusJet prepares for its first flight (Image: Mark Mocho)
A low pass of the BonusJet (Image: Bill Pearson)
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A low pass of the BonusJet (Image: Bill Pearson)
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Gliders that have engines which can be used for take-off to remove the need for catching a tow to altitude by an airplane or a winch are quite common now. Such engines are usually of the electric or small-piston motor variety, but New Mexico-based company, Desert Aerospace, has gone a step further by fitting a glider with a retractable jet engine.

The ‘BonusJet’ is a two seat, high performance, self-launching glider based on the TST-14 sailplane produced by TeST in the Czech Republic. It features a PBS TJ-100 turbine engine (also produced in the Czech Prepublic) on a retractable pod located directly behind the cockpit. The jet engine, which is designed for use in unmanned aerial vehicles, folds down into the fuselage once soaring altitude is reached. A cooldown period of 1.5 minutes is required after engine shutdown before retracting the engine.

Once the engine is drawn into the fuselage retractable doors close over it to form an aerodynamic covering and leave the craft looking like any other glider. Three switches in the cockpit control all the engine's extend/retract/start functions: one opens and closes the doors, one extends/retracts the engine and the last starts and stops the engine.

BonusJet takes to the skies (Image: Bill Pearson)
BonusJet takes to the skies (Image: Bill Pearson)

The engine weighs 42 pounds (around 1/3 the weight of equivalent piston engines) and produces 240 pounds of thrust but does burn through more than 20 gallons per hour. The BonusJet can carry 24 gallons of fuel, giving it a jet-powered flight time of around 1.5 hours. Although, with initial flight tests using the engine showing a climb rate in excess of 900 ft/minute the pilot shouldn’t have to run the engine for very long to reach soaring altitude and the team is projecting a sea level climb performance approaching 1,000 ft/minute.

Desert Aerospace also projects a sea level takeoff distance of 500 ft., with the craft achieving takeoff distances of approximately 700 ft. in tests at the company's home airport in Moriarty, New Mexico, which is at an elevation of 6,200 MSL. The company says this makes the BonusJet's takeoff requirements considerably better than any other motorglider it has compared it with, such as the Stemme, DG-505 and ASH-26E.

Desert Aerospace says phase one flight tests have been completed but is continuing to measure performance with the BonusJet flying regularly as a soaring aircraft. In the near future, the company plans to start selling the BonusJet at a price it says will be much less than existing self-launching gliders from more expensive German manufacturers. Currently the company is projecting a cost of around US$175,000, including jet engine installation, basic instruments and trailer.

Check out the videos below to see the BonusJet in action.

Via Wired

BonusJet_moriarty_nm.wmv

engine_run_2.wmv

6 comments
Jonathan Hatfield
Seems like a gimmick to me. The beauty of a retractable piston engine is that you don\'t have to carry as much ballast. The plane needs ballast and rather than dead weight the piston engine made perfect sense. Now you will need more ballast since the jet is lighter. I doubt you could carry enough fuel to make up the difference so you are back to dead weight. I would think the piston engine would be more efficient too so all you are left with is the \"cool\" factor. It\'s not like it\'s going to be faster. I\'m pretty sure the piston engine can exceed Vne if not careful.
Ed
Can it still be called a glider if it has fuel and a jet engine? Kinda think that these two items negate the term \"Glider\" And sure, the engine weighs 42 pounds, but 24 gallons of fuel weighs over a hundred pounds! So, two adults, plus engine and fuel? That\'s a *VERY* heavy glider!
donwine
It is nice to see a new application work. I love the sound. The biggest draw back is the jet out preforms the prop at higher altitudes but the prop out out preforms the jet when close to the ground. It is a shame to turn it off and not use it for long flights where it is most efficient. Our amphibious glider will be on You Tube very soon.
christopher
They\'re right - the PBS-TJ100 does burn \"more than 20 gallons per hour.\" 15 gallons more to be precise. That sucker drinks 35 gallons per hour (>130 liters) actually. I guess their idea of \"jet powered flight time\" includes the time they take to drift back to earth with the jet turned off afterwards... Small craft never use jet engines for this exact reason - they consume more than 10 *times* more fuel than regular engines in the kinds conditions they fly in. They do sound awesome though :-)
Craig Jennings
It\'s very James Bond
Neil
Ohhh. I read \'a new Mexico-based company..\' and I thought, wow, someone in Mexico inventing something. Then I read it again.