FAQ raptor 105
| General |
|
Why compression ignition?
|
| Compression ignition engines, commonly called diesel, have certain significant advantages in many applications. Among these are reduced fuel consumption, lower-cost fuel, and significantly reduced fire hazard. Potentially longer life and greater reliability are also possible. |
| I see that you didn't mention weight. Aren't diesel's heavy? |
| Ordinarily yes. Raptor has gone to great lengths to produce an engine that is comparable in weight with equal HP gasoline engines, much less existing diesels. |
| How do you compare weight wise to other engines in your HP class? |
| Gasoline
powered aviation engines in this range generally weigh 1.5 to
2 lbs per HP. For example, the Rotax 914 is rated for 100 HP continuous
operation and weighs 166 lbs for a weight to power ratio of 1.66 to 1.
The Raptor 105 produces 105 hp continuously and weighs 179 lbs for a weight to power ratio of 1.7 to 1. |
| How about emissions? I want an environmentally friendly engine. |
| Raptor Turbo Diesel is committed to developing
environmentally responsible engines. Our Raptor brand engines are environmentally
friendly in two ways. First, our compression ignition engines use
up to 25 percent less fuel than comparable gasoline engines, thus conserving
valuable petroleum. In addition, we currently meet all applicable emissions
regulations and are ready to meet proposed future standards. |
| Why should I buy a diesel? Most aircraft in this horsepower range have gasoline engines. |
| The advantages of diesel engines are already well-known. The problem has been in two very important areas; weight, and cost. Up until now both the weight and the cost of small diesel engines has been prohibitive for aircraft. Our Raptor brand engines are a direct replacement for gasoline engines and we intend to provide them at a cost that is comparable with existing gasoline engines. |
| What country are these engines imported from? |
| All Raptor engines are made in the United States. |
| Diesel Related |
| What is a "common rail" diesel? |
| In theory a common rail
diesel system works just like the fuel injection in your car. A pump
provides fuel at a certain pressure to a reservoir, called the rail. All of the injectors are connected
to the rail, hence the term 'common rail'. The injectors open and close
as commanded by the fuel injection computer, usually referred to as the
ECU (Electronic Control Unit) or ECM (Electronic Control Module). In
practice, the differences between spark ignition and compression
ignition fuel injection systems are significant. In your car, the fuel
is maintained at a constant pressure, usually between 36 and 72 psi. In
the Raptor common rail system the fuel pressure is variable, depending
on engine need, and runs between 5000 and 26100 psi (no that's not a
misprint, it's 26,100 psi). Timing the fuel injection also requires far more accuracy than a gasoline engine. |
| What is the difference between #2 diesel and Jet A ? Do I need an additive to run Diesel ? |
| Diesel
#2 is the fuel you can get at a regular gas station. Jet A is the jet
fuel commonly available at most airports. #2 diesel is a better
lubricant than Jet A and in the past most diesels engines required a
lubricant additive to run Jet A. The Raptor system was designed from
the onset to use Jet A and does not require the use of any additives.
Interestingly, even though #2 diesel and Jet A have different weights
per gallon, a fact that pilots need to keep in mind when computing
weight and balance, they have almost the same energy content per unit
volume. This allows the pilot to mix approved fuels in any ratio in the
tanks. |
| Are there any special inflight fuel adjustments that are needed ? |
| No, the Raptor 105 is single power lever. The ECU takes care of all fuel adjustments. The pilot simply moves the power lever to the desired power setting. |
| Which has better fuel economy, the Rotax 912S or your diesel ? |
| We do, hands down. In the coming weeks we'll post fuel consumption graphs that you will be able to compare to the published Rotax data. |
| How will engine performance be affected by altitude? |
| Because the Raptor 105 is a turbo diesel it will maintain sea level performance up to its critical altitude. Beyond that point power
will start to decrease at a rate somewhat less than a normally
aspirated engine. The actual critical altitude can only be determined
by flight tests but our preliminary results indicate that we will be
able to maintain sea level power to at least 10,000 feet msl. |
| Miscellaneous |
| Is your engine compatible with any of the modern glass panel/engine analyzers? |
| At the present time the
answer would have to be a qualified 'yes'. In the future we intend to
work with any interested electronics manufacturers to ensure
compatibility. Technically speaking, the Raptor ECU implements a subset
of SAE J1939 over CAN II for communicating with external devices. If
there are any particular glass panel/engine analyzers that you are intersted in, feel free to call us, or better yet, have the manufacturer give us a call. |
| Will the Raptor 105 work with a 24v electrical system? |
| Basically
no. All of the diesel components were designed to work with 12v
systems. It would be theoretically possible, but certainly not an easy
task. |
| Why have you chosen to use such a small speed reduction ratio? I would prefer to operate my propeller at a lower RPM than 2500 in order to achieve higher efficiencies and lower noise levels. |
| 2500 RPM was chosen as the best compromise between efficiency and propellor diameter. The Raptor 105
was designed to be a replacement for the Rotax 4 cyclinder engines in
the Light Sport Aircraft market. As such we wanted our engine to be
able to use already existing propellors. To turn the engine much less than 2500 RPM
would require larger diameter propellors. This would be a problem for
most LSA airplanes. Since the engine only needs to turn 2800-3000 RPM
to achieve our desired power, the ratio worked out to what you see. |
Other infoIf you have any questions that you think would be of general interest, let us know and we'll post them here.
