Frequently Asked Questions
- What’s the difference between autostart and manual start?
- Why does Wren give the manual start option?
- Does manual start mean you use a starter wand?
- What is a two-stage engine?
- What warranty do Wren give on the engines?
- Wren have “Open Days” at the factory several times a year. What happens on those days?
- Do Wren ECUs comply with failsafe requirements?
| Question: | What’s the difference between autostart and manual start? |
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| Answer: | Wren have two different Engine Control Units, the autostart and the "ECO" manual start. The autostart ECU controls all the start functions – glowplug, gas supply (propane/butane) and starter motor. The pilot simply gives a command using the transmitter stick. The manual start system requires the pilot to connect the glowplug and the gas supply, then operate the starter motor using a switch. The ECU monitors the temperature and when the gas has heated the engine sufficiently the ECU will start the pump. At this point the sound of the engine changes as the kerosene burns, and the ECU will have taken command of the engine. The pilot can then unplug gas, glow and starter. |
| Question: | Why does Wren give the manual start option? |
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| Answer: | The advantages of manual start are that it is small, light, and easy to install. The starter battery and gas supply stay off-board, the ECU main unit is smaller and lighter and it doesn’t require gas and fuel solenoid valves. It’s also less expensive. Wren pioneered the smaller engines (see About Us for details) and we believe that if you are using a small, lightweight engine in a smaller, lighter model it is a good idea to keep the engine weight and installation to a minimum. That’s why, unlike other manufacturers, we give this option. |
| Question: | What is a two-stage engine? |
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| Answer: | Two-stage engines were developed in full-size aviation to make better use of the power produced by a jet engine. A jet engine uses the “suck-squeeze-bang-blow” principle and the hot gases streaming out from the exhaust provide propulsion (thrust). However, this is very inefficient and a large amount of the heat energy is wasted. So a method was devised whereby the hot gases were channelled through gas passages and used to turn a second turbine, which powered a turboprop propeller or helicopter rotor. This gives three main parts to a two-stage engine: First stage, the jet engine which generates the gases. Second stage, the gas passage (interstage guide vane) and second turbine (power turbine) Gearbox, with a shaft from the power turbine and reduction gears transferring the power to a prop or rotor. The two-stage engines are about 4 times more efficient than the single stage ones, giving much more power from the same amount of fuel. |
| Question: | What warranty do Wren give on the engines? |
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| Answer: | Wren Turbines warranties the engine and associated equipment, free of mechanical defects in workmanship or materials for one year after purchase date, to 200 starts, or 20hrs running whichever comes first. |
| Question: | Wren have “Open Days” at the factory several times a year. What happens on those days? |
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| Answer: | The factory is open from 10am-4pm to anyone who wants to attend, free of charge. Some people chose to assemble their MW54 kits on Open Day, and if you buy and build an engine that day we guarantee you will leave with your new engine having been test-run. Other customers bring MW54s which need test running or which have problems, because on Open Day all help and advice is free. If your kit-built engine needs repair you will only pay for the parts and will do the repair yourself under the supervision of the Wren team. Other people bring planes and helicopters to show. The “shop” is open for purchases of spares, jet magazines and the useful bits-and-pieces needed to install the engines. Free tea, coffee and home made cake is available all day. If you are interested in turbine engines and their manufacture you will learn a lot, meet interesting people and enjoy a good day. Click For Details... |
| Question: | Does manual start mean you use a starter wand? |
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| Answer: | Not necessarily. You can use a starter wand, but most people prefer to have the onboard starter with the integral FOD screen. Both systems use a switch to operate the starter in a similar manner. |
| Question: | Do Wren ECUs comply with failsafe requirements? |
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| Answer: | Yes, they comply with the UK (JMA) requirements and also with those of the AMA in the USA. Click here to download further details. If you are unable to open the file please go to http://www.adobe.com/reader and download Adobe Acrobat Reader |