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The Ganagobie Lives!
New Life for a Ganagobie
James Lobet's final Ganagobie got an engine rebuild shortly before his passing, including addition of a Diehl Accessory Case package and bottom mount starter. After a week of work on the Ganagobie, here's a video of its first start:
The Ganagobie Sandpiper
The New Zealand Ganagobie
James Lobet's final version of the Ganagobie, the Ganagobie Mousebird incorporated a number of modifications/refinements to his original Ganagobie design. These included:
greater visibility with the addition of a rear window,
greater cockpit room with a box-frame bottom,
robust and wide stance Grove landing gear (Jame's 4th landing gear design/install on the Mousebird),
vertical fin wingtips for improved lateral stability and decreased induced drag (wing tip vortices) , and
a somewhat more powerful 55hp 1600 VW engine.
These refinements improve the Ganagobie Mousesbird's recreational flight performance and use characteristics. The Ganagobie Mousebird ZK-JLO, was purchased by Owen Hughes in June 2023. Dr. Hughes hopes to update and modify the Ganagobie to playing to the strengths both of the airplane and its New Zealand home. The Ganagobie Sandpiper will incorporate modifications designed to improve "off airport" and beach based operations! Off airport operations are both remarkably common and important in New Zealand. Additionally, it is legal to land on New Zealand's many fine and deserted beaches.
The combination of minimal population and spectacular scenery makes New Zealand a perfect place for off-airport recreational flight. One of our main missions/uses of the Ganagobie Sandpiper will be off-airport and beach landings. New Zealand's striking beauty can be accessed by air - and it is legal to land on its beaches. Beach landings?!
However, we want to take it to the next level.
A new Ganagobie?
The Ganagobie Mousebird could benefit from modifications designed to improve off-airport recreational flight characteristics.
Specifically:
Increased power for better short-field and climb performance.
High-lift or stall reduction devices to improve slow flight / STOL performance.
Large main-gear tires for improved soft-field/rough-field performance.
Large tail wheel for improved soft-field/rough-field performance.
New Instrumentation.
1) Increased power for better short-field and climb performance.
The Ganagobie Mousebird's Volkswagen 1600 engine (known as a Type 126) featured a displacement of 1584 cc's, a bore of 85.5 mm, a stroke of 69 mm, a compression ratio of 7.7:1 and dual Solex 30 carburetors feeding single port heads. This engine produces maybe 65hp at 3,100 rpm. We plan to install 94mm bore pistons and barrels, which would bring the engine displacement up to 1914 cc's - a 20.8% increase. Additionally, new dual port heads and electronic ignition is expected to provide ~5% better performance. Other minor upgrades will include an additional 2-liter oil sump, new 30mm oil pump, new aluminum push rods, and titanium lifter nuts. Overall, the engine should have both improved hp (~70hp) and reliability.
Re-powering an airplane is a complicated and expensive process. Performance, stress, weight, and fuel-flow / consumption all need to be considered. Worse, boosting the performance of VW engines is fraught with reliability issues. Substantially increasing power also increases stress, wear, and heat. Due to these considerations - re-powering the Mousebird will be one of the last modification we perform.
2) High-lift or stall reduction devices to improve slow flight / STOL performance.
The Ganagobie Mousebird's wing has a NACA 23012 airfoil without flaps or any other high-lift / stall control devices. The NACA 23012 airfoil (12% thickness version of NACA 230 series of airfoils - which have 2% camber and maximum thickness at 30% of chord) is a highly respected low-drag airfoil capable of good speed with low power, and very low pitching-moment coefficient (pitch force generated by separation of center of gravity from center of lift) that must be counteracted with elevator - which is a complicated way of saying the airfoil is very efficient. The NACA 230 series airfoils has been used by many aircraft including the DC3, the Beechcraft Bonanza, Vans RV's, and both the Osprey II Amphibian and the Cavalier. (Some may be noticing my connection to the Airfoil!)
One of the downsides of of the NACA 230 series airfoils is a dramatic/pronounced stall-break. This is not an ideal characteristic for STOL operations - where slow speed, stall-adjacent operation is essential. Rebuilding the wing with a different airfoil is well beyond the scope of our initial efforts with the Ganagobie - as is rebuilding the wing to incorporate flaps. That leaves three likely wing modifications: vortex generators, leading edge cuffs, and leading edge slats. Both leading edge cuffs and slats are still fairly involved, so we will start with vortex generators.
Vortex Generators (VG's) are highly effective at reducing stall speed (good) - but they also tend to generate a more dramatic stall-break (bad). If you read about vortex generators, you'll read that they work by re-"energizing" airflow over the wing.
Here's what that actually means - airflow along and following the contour of the wing is how lift is produced. Essentially, lift is equal to the mass of air diverted downwards (don't start with that Bernoulli crap). Skin friction reduces the speed of airflow very close to the surface of the wing.
As the angle of attack increases, airflow along the top of the wing must make a steeper more dramatic acceleration downwards to follow the contour of the wing. Pulling the airflow down to follow the wing's top surface causes (or is caused by - OK, maybe a bit-o-Bernoulli) low pressure along the top of the wing. This low pressure increases the depth of the turbulent boundary layer. At some "critical angle of attack" the air flow separates entirely from the wing contour -detached flow - and that is a stall. Air actually flows forward along the the top of the wing from the high pressure region at the wing's trailing edge towards the leading edge - exactly the opposite of what we want.
Vortex generators work by mixing the quickly flowing (high energy) air above the boundary layer into the slow flowing (low energy) air down in the boundary layer. This keeps the air moving down along the contour of the wing - and as long as we are moving air down, we have lift! Vortex generators let us achieve a greater angle of attack with the wing (and thus get more lift at low speed) before critical air flow separation happens.
We will measure performance of the Ganagobie before, and after installing vortex generators.
For the contentious among us -> Yes, VG's do tend to make the stall break even more dramatic - so not a good thing?. While yes, with VG's when the new VG aided Critical Angle of Attack for the wing is exceeded, the loss of lift usually happens more quickly. However, VGs seem to dramatically increase controllability right up to stall break by improving airflow over the ailerons. Additionally, VGs are often placed on the bottom of the elevator and on each side of the rudder - again increasing airflow over these critical control surfaces. Finally, VGs often reduce stall speed ~ 10-18%. These advantages have driven rapid adoption of VGs in the Short Take Off and Landing community.
3) Large main-gear tires for improved soft-field/rough-field performance.
One of my main missions/uses of the Ganagobie Sandpiper will be off-airport and beach landings. New Zealand's striking beauty can be accessed by air - and it is legal to land on its beaches.
The Ganagobie Mousebird has Azsusa 5" wheels with 5.00-5 tires - standard on many small aircraft. These are light-weight, inexpensive, and and reliable for smooth/hard strip flying. But for soft/rough fields, larger tires significantly reduce the possibility of damage. Unfortunately, most large (often called Tundra) tires are remarkably expensive, and would probably be a little overkill on the tiny Ganagobie. The Nanco N800 tires are a fantastic alternative to custom tundra tires for very very light aircraft. They have a nice combination of diameter and width. The Nanco N800 tires have a substantial diameter of 21" making them well suited to mild to medium rough fields. The Nanco N800s also have a nice float width (12"), making them well suited to soft fields and sand.
The Ganagobie with Nanco N800 21" Tires
New Wheels
The Nanco N800 tire requires a 8" wheel/rim. Luckily, the 8" Azusa Spinner wheel is a direct bolt in replacement to the AzusaLite 5" wheels on the Ganagobie Mousebird. The 8" Azusa Spinner wheels do not have the same bolt pattern used on the 5" wheel's, which matters because the Ganagobie's breaks are mounted via these rim half clamping bolts. Luckily, the 8" Azusa Spinner wheels do have built in embosses on the inside of the rims that can be drilled out to match the brake mounting of the AzusaLite 5" wheels. This helps make conversion fairly easy.
8" Azusa Spinner Wheel
Check out the old 5-500 standard aircraft tires vs the Nanco N800 tires!
4) Large tail wheel for improved soft-field/rough-field performance.
The Ganagobie is a tail-dragger, which is the preferred configuration for rough/soft field operations. This is because the taildragger configuration increases propeller clearence from the weeds/rocks, and becuase a nose wheel is usually far more vulnerable to damage from rough feild impacts. (Oh shush you Zenith-atics).
The Mousebird was built with the standard Maul small tail-wheel. While the Maul tail-wheel is reliable, it is small and heavy and would sink into soft surfaces like soft turf or especially sand! A light weight replacement was built that could significantly improve soft/rough field and beach performance.
5) New Instrumentation.
James Lobet built the Ganagobie Mousebird with minimal instrumentation, and then slowly added additional instrumentation on pods mounted around the windscreen. Engine instrumentation can provide optimal operation and early warning parameters critical to keeping you in the air. James added oil temperature and pressure, but did not include critical Cylinder Heart and Exhaust Temperature (cht and egt) instrumentation. Since heat is one of the VW engine' weaknesses, it seems prudent to monitor these temperatures. Additionally, James and I fly with charts on a phone or ipad - cluttering an already tight cockpit . Here's a photo of Jame's final instrumentation of the Mousebird:
Ganagobie Mousebird Instrumentation:
Digital technologies make it possible to significantly improve instrumentation capabilies without increasing weight, layout space, and "clutter". The goal is to economically and reliably provide critical information about engine, flight, and location parameters that is easily grasped and used - in the least amount of space. Afterall, cluttering and obstructing the amazing visibility out of the new Ganagobie Sandpiper would be a crime. Here's a photo of the "work in progress":
Ganagobie Sandpiper Instrumentation:
Wingman Electronic Flight Instrument System and Engine Management System
https://www.aircraftinstruments.eu/
This innovative EFIS/EMS collects and processes data from from flight and engine probes the broadcasts the data to linked tablets or phones.
The Ganagobie Sandpiper's new instrumentation is built around the Wingman combination of flight and engine instruments. Display of instrumentation and charts utilizes both an iPad mini and an iPhone. The Wingman package includes sensors for 4EGT, 4CHT, oil temp, oil pressure, fuel flow, manifold pressure, outside temperature, attitude, altitude, airspeed, vsi. Neatly, the iPad mini and the iPhone make for redundant easily swapped displays (I can display EFIS/EMS on either with just swipe).
For those like me that fly IFR frequently, I Follow Roads that is, you can split screen the wingman setup so that Wingman EFIS/EMS is on 1/2 of the iPad, and an air chart is on the other 1/2. Then on the iPhone I have a moving road map (google or apple maps). This set up gives me the information I want and need in the very limited panel space. Steam gauges are retained for a few critical items. And all was remarkably economical. I've just started using this setup. If it works as its supposed to I'll give a full report.
You can checkout the Wigman system here: https://www.aircraftinstruments.eu
New LED Anti-Collision Strobe and Landing Lights
New LED Anti-collision strobe and landing lights have been installed. The LED lights produce significantly more light for only a fraction of the power. Importantly, they are both smaller (lower frontal drag) and lighter weight. Additionally, a switched wing-wag strobe unit was installed to enhance the anti-collision effect of the LED wing lights. Here's a movie of their operation (they are even brighter in person than in the movie).
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