This past weekend I was able to view a Fisher R-80 in person for the first time. It’s a nice looking airplane and everything seemed to be falling into place. Then came an in-depth conversation with the builder/pilot. The following concerns came to light:
- Build time was significantly longer than advertised, roughly 2,400 hours as opposed to 700. That’s twice what I was hoping for.
- Stall speed seems to be in the 45-50 mph range. That’s 10-15 mph higher than advertised.
- Cruise speed (75% power on a Jabiru 3300 motor) is about 70-75 mph, about 10 mph less than advertised.
- The aircraft flies with a pronounced nose-high attitude, and level flight could not be maintained without using maximum elevator trim.
Each one of these points in its own is a concern. Each could be enough to dissuade me from building an R-80. Before making any decisions I wanted to hear from other builders and pilots, to find out if these are common faults with the type. I scrounged the internet for the contact information of as many R-80 builders and owners as I could find. In the end I found 10 email addresses, and sent each one a very brief survey. A couple of the emails bounced, a few more have not yet been answered, but I’ve gotten 5 responses. They all tally with what the local builder found.
- Build times range from 2400 to 7000 hours
- Stall speeds range from 45 to 55 mph
- The nose-high attitude is a universal trait, at least when built to plan. Some builders opted for a higher angle of incidence of the wing, I’ve not yet heard back from any of them to find if it made a difference.
- Empty weights came in about 150-200 lbs higher than advertised, in some cases leaving as little as 180 lbs of useful load for pilot, passenger and baggage.
- Stall behavior is to “mush” at a descent rate of over 1,000 fpm. The aircraft does not drop its nose nor self-recover from the stall. A close watch must be kept on the VSI at low altitudes.
All of this is bad news for this 80% scale Tiger Moth. I haven’t made a firm decision yet, but I’m certainly entertaining all options at this point. I would like to see if the problems can be overcome aerodynamically… that’s one of the great things about building an experimental plane, you are under no obligation to follow the plans. But, it’s always possible that it cannot, or that it would take too much work, or that the improvement can’t be assured without building the plane anyway. If that’s the case, I’m afraid I’ll have to walk away from this project altogether.