SEPTEMBER 2015 Questions....

Do you recommend a specific propeller for your Spyder Engine on various airframes, and if so, what have been your experiences with it?

    There have been several propeller that I have used over the years and I have found them to be one of aviations mysteries at time.  But here are some of my experiences...

    KR2S (2700cc) - Prince P-Tip 52/50  Worked well at high speed (180) but tended to cavitate on takeoff.  Suffered a bit on climb.  I'm sure I could have had Lonnie make another that would work better.  The pitch numbers are a trial/error thing...cost @500.00
    (same plane)  - Sensenich Wood 54X54 - this prop worked very well as a balance with takeoff/climb performance and cruise.  I lost a couple mph compared to the Prince but it had a great balance and cooled a bit better due to the larger root area.  Sensenich is very good with making matched prop sets.  If I order another 54X54 it would behave very closely to the first one.  Cost about 850.00

    Saberwing (2700cc) - I have been using the Sensenich prop lately 54X54 as I had on my KR2S and it performs very well.  I cruise 150mph (21"map") and top out at 180mph (27"map).  I did fly with a very light Props INC prop (3.5 lb) for a while.  It did perform well and is less expensive prop to purchase.   The one thing I noticed with the lighter props is that you lose a lot of mass so when you shut down the engine just "stops".   
 Tailwind (2700cc) - I have flown this plane with three different props - the Sensenich 54X54, the Props Inc 54X52, and a three blade Warp Drive ground adjustable.  I do get just a bit more speed with Sensenich and Props Inc props (+7 mph) but the airplane seems to run much smoother with the three blade.  There is something about that airframe that is different.  Makybe it is the larger sides of the fuselage that feel the pulses on the the two blades but there is a noticable difference.  The climb and takoff are great with Warp Drive as it has a better static thrust design.  It will tend to drop off in performance on the top end because of blade design.  Mine has the rounded tips for higher speeds but still hard to get the plane over 150mph straight and level...however I didnt build it to be a speed machine, so I will stick with it. Price on a three blade Warp Drive is @1100.00
 Zenith 601-750  I have flown lots of Zenith products and most have had a Warp Drive ground adjustable two blade (66") prop on them.   Because these airframes aren't speed queens this combination works very well.  The provide a great amount of static thrust for impressive rollout and climb, and are adjustable to fine tune your top RPM.   I don't use them on the quicker planes mostly due to ground clearance.   They are well built and beefy.  They aren't cheap though.  Typically @900.00.  On our Spyder engine we use the HP (heavy duty hub).  Fits into our 12" spinner nicely.  The nickle leading edges help reduce wear from grass and dirt strips (and rain) as well. 
    Sensenich makes a great prop for these as well.  You will have to do some research to find the best combination for your design.  Typically a 66/38 will work well on a 750 but I will get more feedback and add it to a future prop page....

Do you recommend a maximum G-loading for the Spyder / IFB / propeller combination?  I am interested in doing some basic aerobatics in my Sonex.

When we designed the motor mounts for the Sonex and a couple other planes we loaded them in-house to 6 Gs positive.  This is the limit I would use however most aerobatics on these aircraft I would limit to 4.5 Gs positive.  The engine/prop/IFB will handle loads in excess of 10 Gs easily.  If you look at our IFB installation you can see the strength of our design.  The hub in integral to the crank (no bolts or safety shafts to fail) - the bearings are very large and incorporate the thrust loading (30% larger than stock) at the front housing.  The hub is "locked" into the housing so if there were a crankshaft failure the parts stay together.  (IFB Unit Video)  Our hub was designed to handle a constant speed prop and its mechanisms through the hollow shaft.
    As far as negative G loads you are limited because of several factors.  The fuel system on most Sonex aircraft (and most of our designed aircraft as well) rely on a gravity fuel system.  The flow of fuel to the carb (Aeroinjector in our case) would be interupted and fuel starvation may occur.  The Aeroinjector will draw fuel out that is still in the lines so it would not be immediate lose of power but shortly after the manuever.  A bit of flight testing would reveal the tenancies your particular aircraft.   A inverted fuel system is not difficult to arrange.  Remember as well that the oil system is a wet sump system.  This means that in negative G the oil would move upwards in the case possibly uncovering the oil pickup.  Most simple aerobatic manuevers we do are positive G or negatve for a few seconds only so most of these issues need only be understood and monitored.  Sustained negative G manuevers are not recommended with our standard installation.
    Can you make a dry system?:  Yes - it is not difficult.  We are considering this for one of our aircraft and will have more about that later.
    Because I know your plane, remember that any aerobatic manuevers should be done with empty wing tanks and no passanger.  (check FARs) 

Is it reasonable to convert the 100HP Spyder to the 120HP version?  Do you have any details/recommendations for such a conversion?

There are some major differences between the two engines, however, it is an easy conversion.  Take the 100 off the mount and bolt the 120 on!   The 120 has a new, counterweighted and stroked crankshaft, new design rods, and new design pistons.  Is is much more cost effective to build a 120 and then swap out.  We will pro rate any of our engines for exchange or come up with a equitable exchange with any customer of ours or even with people changing from a competitor design to ours.   All of the auxiliary or FWF parts are similar between the two engines and don't have to be changed.  What can you expect as part of the exchange?  You will probably have to change out the propeller or change pitch but not absolutely necessary (depending on installation).  Expect that CHT's would be slightly higher on climbouts - however you could get to altitude more quickly and then throttle back to cruise configuration where temps will stabilize.  Any given power setting will give you higher performance however remember that the airplane will perform the same at same RPM (with same prop).

Would the Spyder engine benefit from a ground-adjustable propeller or a three-blade version?  I'd like to maximize cruise when I can, but also have the ability to have a "climb prop" when needed....   

As stated above, I am using a three blade, ground adjustable, warp drive on my Tailwind at this time.  The Warp Drive suffers on the high speed arena due to airfoil design so it is really maxed for my performance, however it had improved the takeoff and climb performance.   There is more testing I can due with blade angles and such to improve/modify the performance according to my needs.   This type airframe would probably do much better utilizing Sensenich's adjustable composite blade system since the blades are a better design...but higher cost.   It is in our skunkworks right is our inflight adjustable prop design. (that would be the best option)