THE BOXER
BRIEF !
PROPELLERS.....
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 now...as is our inflight adjustable prop
design. (that would be the best option)
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MORE QUESTIONS !!!!