Adventure Airplane w/ Motorcycle

#1
In this thread, I'll share pictures and details about my favorite adventure vehicle; an airplane + motorcycle combination.

Background: I love aviation but it didn't take long to grow tired of the same old fly-in restaurants. I wanted to fly to museums, beaches, trail heads and climbing crags; I needed an airplane with door-to-door capability! After finishing college, I found my first engineering job in Florida. I saw plenty of motorcycles on my way to work every day. Eventually, I thought, "Bingo! Why not modify an airplane to carry one of those?"

I was 10 months into my engineering career and it seemed like a great idea to quit my job and start designing a motorcycle belly pod. I began building the prototype in my garage and it quickly grew into a full-time business. Eventually, I got to enjoy some extraordinary adventures with the prototype. However, there was one problem... I wasn't making enough money to build one for myself! Eventually, I started a second and more lucrative business. It's been a long road, but I'm finally back to building my very own adventure airplane. When it's finished, I'm looking forward to expanding my radius of living and enjoying adventures all over the west coast. My Chevy Express camper van takes me on many adventures in northern California, but it's a game-changer to have a 1,000 mile range for day trips! The long-term goal is to plan a leisurely 6-month trip around the world. The airplane will allow me to hop from one country to another and the motorcycle will allow me to explore each destination.

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#2
I selected the Yamaha XT-225 for a number of reasons. First, I wanted a motorcycle with at least 200cc because some highways don't allow vehicle with less than 200cc. Legally, the XT-225 can go anywhere a 1,000cc Harley can go! Second, weight was very important. The stock XT-225 weighs 238 pounds and I was able to reduce this to around 220 pounds with mods. Finally, the XT-225 has a narrow build and folds to 12.5" wide after mods.

Here's a picture of a stock XT-225 and a modified one.

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#3
The original concept of tossing a motorcycle underneath an airplane wasn't so simple. As already mentioned, weight and dimensions are critical. It needed to be unfolded/assembled without tools or assistance. It had to be modified to prevent gas and oil from leaking.

Here are some of the mods:

Folding Handlebars - Funny story... I rode my XT-225 to the machine shop to pickup parts for my prototype folding handlebars. On the way home, an oncoming car turned left and took me out. I woke up in an ambulance and the bike was totaled. Ironically, the stock handlebar ended up folded! I decided to call it folding handlebar version 1.0. Unfortunately, whatever folded my handlebar also broke my wrist in two places, but I was back to work by the end of the night.

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Plumbing - I cut up the fuel tank and added a different type of fuel bung and vent. When the bike is on it's side, fuel from the carb and vent lines is captured in a model airplane fuel tank. After the flight, a 12V pump returns the fuel to the main tank.

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Wheels - I laced smaller wheels onto the stock hubs. I also changed out the sprockets and geared it a little more towards on-road use.

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Suspension - I lshortened the front suspension. This was done by cutting the springs and adding simple spacers. The rear shock had to be built to speck. I also optimized the suspension more for two-up highway riding.

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#4
Center Stand and Quick-Release Axle - I designed a center-stand to support the bike while the front wheel is attached/removed. It has an over-center spring that can either extend or retract the center stand. In the earlier video, you can see the center stand extend when I lift the front of the bike.

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Lighter Fenders

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Decals - The airplane, motorcycle and helmet had to match!

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#5
The pod is constructed from foam and fiberglass. It's vacuum bagged for reduced weight.

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There are streamlined rollerblade wheels on the bottom.

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A lightweight winch system is built into the pod. The winch, which is powered by a cordless drill, allows the loaded pod to be attached or removed from the airplane in about a minute.

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#6
I made fiberglass cradles to hold the motorcycle in place. This was actually once of the more frustrating molds to make! When the pod is winched up to the airplane, the motorcycle becomes sandwiched between two sets of cradles; there's no need to tie anything down.


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#7
A 220 pound motorcycle weighs 1,100 pounds when you pull 5 g's! It took a lot of design and testing to optimize the pod structure. The weight of the pod, winch system, latches and rollerblade wheels is about 35 pounds.

Load testing a simply supported material sample.
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Measuring deflection.
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Limit load test of the prototype pod.
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#8
The airplane is a Van's RV-10. It's a kit-built airplane so I was able to modify it without going through FAA certification. The RV-10 has a great useful load, cruises near 200mph and has a range of nearly 1,000 statute miles. The airframe mods were pretty simple. I had to move a couple antennas and I designed fuselage hard-points where the pod attaches. After load-testing the hard-points and updating the weight-and-balance, it was time for flight testing! The drag penalty was minimal (~2 mph) and handling was benign.

Here are some of the latch components that attach the pod to the aircraft. There are four latches and they are designed to be fail-safe; if any latch were to fail in flight, the remaining three can handle the resulting loads.

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Here's one of the fuselage hard-points. I added inspection panels so they can be examined during annual inspections.

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The first flight!

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#9
The prototype was tons of fun to fly around. As soon as I'd start lowering the pod, people would always come out of the woodwork to see what was going on.

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After completing the flight test hours, I took my girlfriend to a fly-in lunch in Sheboygan, Wisconsin. As usual, everyone ate hot dogs and talked about airplanes. Eventually, pilots crawled back into airplanes and flew home. At that point, we hopped on our motorcycle and drove to town. We ate ice cream on the beach, hiked in a state beach park, toured the marina and visited an old fire tower. Dozens of pilots flew to the Sheboygan airport for lunch that day, but nobody else explored Sheboygan! That was the first of many fun trips.

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#10
Great vision, incredible stuff! I must admit, as a pilot myself, I was horrified at first until I continued to read and see your educational background, your testing, and your abilities!


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#14
After a little practice, my girlfriend and I got the routine down to about 2 minutes. That's from sitting inside the airplane, to sitting on a running bike.
 
#15
Interesting
The box is a nice tight fit to the belly. What kind of impact did you see on your cruise speed?
I only lost a couple knots. The RV-10 belly is already flat and draggy to begin with, so the pod hardly hurts. At one point, I covered the pod with yarn tufts and found a little separation on the aft sides. At some point, I'd like to install micro vortex generators and see if I can keep the flow attached a little longer.

In my opinion, pilots care about airspeed too much. Certainly, airspeed is important when air racing around pylons at Reno. For transportation purposes, I prefer to think about the overall door-to-door trip speed. NASA did some research on this as part of the SATS program. It turns out that inter-modal delays are a big problem. A 200 knot airplane only has a trip speed of around 100 knots in the real world.

NASA envisioned aircraft with shorter takeoff and landing capabilities, along with thousands of tiny airports, each integrated with public transportation. The idea was to land closer to the final destination and hit the road faster.

Bringing a motorcycle saves a lot of time too. I'm not restricted to airports with ground transportation services so I often land much closer to the destination. I can also pull the motorcycle out much faster than I can reserve a rental car... wait for Enterprise to pick me up... top it off with gas on the way back, etc. In the end, I've found that traditional airplane speed mods shave 15-25 seconds off a typical real-world trip. Bringing the motorcycle often saves 15-25 minutes!

Admittedly, in the last few years, Uber has made ground transportation a whole lot easier. However, it's still nice to be independent and even Uber doesn't work everywhere.
 
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