Be sure to stop by our booth at the 2008 MMOPA convention in Dallas this week.  We will have a drawing to win a cooling mod for your Malibu or Mirage, or if you have a JetProp or Meridian, you can win a turbine compressor wash kit!  Also, we will have the latest information on the status of the FADEC Malibu and Mirage engine project, as well as other projects that we are working on, so we hope to see you there.

-Chad

Okay, many people may think that I may be a little biased on this subject and they would be right, but that doesn’t mean that I can’t perform a factual comparison of the 3-blade and 4-blade propellers with some subjective observations.  So, at the risk of coming across as too much of a “salesman”,(I prefer that the products speak for themselves), I thought I would post the results of a recent test we conducted.  I recently had the opportunity to do a back-to-back comparison of the 3-blade Hartzell and 4-blade MT propellers on a standard PA46-350P Mirage.  Both flights were performed with the same fuel load, cabin load, weight, C.G.  and the OATs were within a couple degrees of each other, to minimize correction errors.

Let’s start at the beginning; weight and balance, pre-flight, taxi and take-off.  The 4-blade does weigh about 10 pounds less, but during the pre-flight I noticed several small dents and dings in the leading edge of the blades, which seems to be common with the 4-blade and yet I have never seen a single dent or ding in the leading edge of a 3-blade propeller, since it uses a much stronger and thicker electro-formed Nickel leading edge.  Next, when we went to pull the plane out of the hangar, it was immediately apparent that it is much easier to contact the propeller blades during handling and movement with the towbar and the 4-blade, due to the reduced distance between the blades thanks to the 90° angle vs. the 120° angle between the blades, potentially causing blade damage.  Once I started the engine and began to taxi, there was a definite difference in the sound of the two propellers from inside the cockpit that was difficult to quantify and would definitely be a personal preference, mine being for the 3-blade,(of course).  I would describe the 4-blade as a “whispy” sound and the 3-blade as a more “throaty” sound that just seemed right to me,(this is where it gets a little subjective as I am certainly more accustomed to the sound of the 3-blade).  Now we get to the best part; the takeoff!  For both takeoffs the wind was calm and by my measurements, the 3-blade took about 6-7% less runway to get the plane off the ground, but the biggest difference was once the plane was airborne, the 3-blade seemed to accelerate to Vy much better than the 4-blade and completely removed that feeling of “underpoweredness” that the PA46 often has during takeoff.  For me, the takeoff performance alone is enough to “sell” me on the 3-blade; it seems to completely change the demeanor of the plane from a lazy land-lover to tiger that is clawing its way into the sky.

Now let’s look at the climb and cruise performance differences between the propellers.  In a stable Vy climb,(110kts), to 17,500′ the 3-blade propeller averaged 71FPM,(7%, -this is a Mirage), better climb rates than the 4-blade, however the 4-blade kept the engine about 10-20°F cooler than the 3-blade,(we have a cooling mod to fix that).  During climb, it was very difficult to notice any difference in noise and vibration; although they did sound “different” from each other, I would maybe have to give a very slight edge in overall smoothness to the 4-blade, but with its extremely light and flexible blades, this wasn’t a huge surprise.  This could also be considered subjective, as I do like the sound of the 3-blade and it just feels like it’s doing more,(and it is!).  Once level at 17,500′, the most impressive comparison yet showed itself; a very repeatable 4-6 knot speed advantage for the 3-blade!  With the OATs within 1° and MAP, RPM, FF and TIT all a near perfect match, the 3-blade was a solid 5-6kts faster with just one reading coming in at only 4kts faster than the 4-blade and one reading at 7kts faster than the 4-blade.  That is really significant, considering the engine is producing the same power and using the same amount of fuel; adding 2.5 t0 3% more speed is noteworthy.  I know the 3-blade is efficient and all of our customers have said that it is either equal to, or slightly faster than the 2-blade on the Malibu, but I did not expect up to a 6 or 7kt difference against the 4-blade!

Now that I have finally had the opportunity to do a real back-to-back comparison and although these tests were performed with a Mirage, the results will also apply directly to the Malibu as the airframes are essentially identical.  I hope it answers that age-old question; which is better, the 3-blade or the 4-blade?  From a performance perspective, the answer is clear and from a reliability and durability perspective, as more and more 4-blade propellers are removed from service due to grease leaks, delamination, leading edge damage and poor field service, history is proving that the “bullet-proof” Kevlar construction of the Hartzell 3-blade is standing up to meet the demands of the PA46 fleet. 

Chad Menne

I thought it was about time to update everyone on what is new at Malibu Aerospace.  Well, for one, the name is new; we are no longer Malibu Power & Propeller, but now,(since November 2007), Malibu Aerospace.  We felt that this name better represents what we do and what we can offer to our customers.  We’re not just engines and propellers, but have other products and services to offer as well, such as custom interior components, cooling modifications, vacuum system upgrades, custom engineering projects and coming soon; LED landing lights.

Many of our customers continue to be very interested in upgrading to FADEC and we constantly get phone calls and e-mails asking for updates.  Well, we are working very hard to finish the FADEC STC and it is working and flying VERY well, but TCM needs to get the engine certified before we can complete the STC, so here we are, waiting for the FAA to grant them the Type Certificate for the FADEC engine so we can finish our job.  We are very hopeful that the engine TC will be granted very soon and it is our goal to complete the STC as quickly as possible after that. 

In the mean-time, we have decided to work in a couple new STCs while we are waiting to complete the FADEC STC.  First, we have started development testing for a Mirage cooling mod to help the Lycoming engine run cooler while you are waiting to upgrade to FADEC.  So far, we have been able to cool the engine 10 to 20 degrees during climb and cruise, with no speed or weight penalties.  We will continue to work towards even better results, but so far, it is a promising improvement. 

The other STC we have been working on is for LED wingtip Taxi/Landing lights and let me tell you, the results are very exciting!  Our prototype unit has proven to produce more than double the light output of the HID light upgrades with a much better light pattern.  These LEDs are the brightest on the market and with eight little LEDs on each wingtip, very efficient total internal reflection optics and half the power consumption of the original taxi lights, they are the lights of the future.  And the best part is… they last over 50,000 hours so you will never have to replace your taxi light again!

We hope to have both of these new STCs available by the MMOPA convention this September, with the FADEC engine upgrade to follow shortly behind.  For more infomation on these new projects, check out the “products” page on our website, www.malibuaerospace.com, or contact us here.

Chad Menne

I often get questions from Malibu and Mirage owners about “what exactly does a FADEC upgrade consist of?”  Well, that is a really big question and the answer starts with research and development; lots of it.  We have worked tirelessly with TCM and Aerosance to develop not only the first turbocharged Continental FADEC engine to be sucessfully certified, but one that has been developed specifically for the Piper Malibu & Mirage.  You may ask, why does it matter that it is specific to the Malibu?  Well, the fact that the Malibu is considerably larger and heavier than all other single engine piston aircraft, yet performs better than planes half it’s size, calls for a specific range of operating criteria that can easily be lost on lighter aircraft. 

For the Malibu you need an engine that can climb strong and stay cool, but also have enough power and thrust to give good climb rates at faster speeds as well.  The secret here is to have an engine that gives good power statically, but also can continue to produce high horsepower at altitude.  The TSIOF-550-J FADEC engine not only produces approximately 370HP under normal conditions for takeoff, but will actually increase power as you gain airspeed and climb.  This is due to FADEC control, effective intercoolers and more efficient turbochargers that lower induction air temperatures and also increase the critical altitude of the new FADEC engine to FL220.

So how does FADEC create more horsepower?  Well, primarily through reducing full power fuel flow to bring the mixture closer to best power, but the trick is to not get too lean, which will make temperatures too hot and risk detonation, but that is where FADEC jumps in.  If the CHTs or EGTs get too hot, FADEC will add fuel on an individual cylinder basis and run the perfect mixture to balance power vs. temperature.  As the pilot, it appears to be acting very much like the thermostat in your car, regulating temperatures during the climb.  In cruise, it produces more power by setting the mixture perfectly for each cylinder through a calibration process, which is impossible without electronic fuel control.  Ordinarily, a single manual mixture control can only set a compromise of six approximately equal mixtures.

Of course making horsepower is half the battle; the other half is turning that horsepower into thrust.  For that we go back to the amazingly strong and well designed Hartzell 3-blade Kevlar composite propeller that we have used in our Malibu M-5 STC and a very similar version has been used on the Mirage since 1998.  During development of the FADEC powerplant we tested other propellers, but could not find a propeller that performed as well as this near perfect propeller airfoil design.  Many people don’t realize that with the combination of the FADEC engine and the amazing 3-blade Hartzell propeller, we are producing nearly 70% more static thrust than the original Malibu.  We will talk about safety improvements and other features of the FADEC installation in future editions of the FADEC Malibu project overview.

Hello and welcome to the Malibu Power & Propeller Blog! This is where you will find the latest information and updates on the projects that we are working on, as well as information on how we analyze and test components and systems to improve them. We also invite you as a reader to comment on project ideas, problem areas that you would like to see addressed and ask questions about any of our capabilities or draw on our experience.

We will generally post one new subject each week and will respond to comments on an ongoing basis. The first subject that we solicit your comments about is what you think about our new website and what additional information would you like to see to make it more useful for you. Welcome and we look forward to hearing from you.