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.
In addition to a local fully completed Fisher R-80, I’ve recently been introduced to several other Fisher Flying Products kit builders in the area. Some built their kits decades ago, as they were learning to fly, and have since moved on to other aircraft. Others are in the process of building right now. I’m really looking forward to visiting a few of the in-progress projects and checking out how it’s done.
Fisher Flying Products seems to be a really great kit-maker. The plans that they provide are full scale, so you literally lay a plan drawing out on a table and then assemble the parts right on top of it. You can theoretically purchase only the plans from them and then source or make all of the parts yourself. But they also offer two levels of kit. The first is your basic laser-cut wooden parts kit, just like building a balsa-wood airplane. The second is their quick build kit. This comes with several of the sub-assemblies already put together for you, including the fuselage sides, wingtips, tail, etc. It allows you to build your aircraft faster, but you still need to do some assembly and then of course there’s the installation of all of the equipment and covering with fabric and painting and all that.
Personally I’m leaning towards the basic kit. Fabricating your own parts can be a pain in that you have to find a good trusted source for the raw wood, and even so you will still have a certain % of loss as you cut into a piece and find a void here or a crack there. That hassle, plus the extra time required, I don’t feel is worth the rather minimal savings over just purchasing pre-cut parts from Fisher. On the other hand, I’m unconvinced that the quick build kit would save me enough time to be worth the increased cost, and there’s a part of me that would very much prefer to assemble (and thus, inspect) each and every part myself.
Either way, it will soon be time to begin concrete steps towards this goal. The first need is a place to build, and since hangars at PAE have a very long waiting list, my first move will be to put my name down for one. $100 deposit and a year or two wait. Once that’s done, the next thing on the list is to get a set of plans. I’d like to have lots of time just studying the plans, figuring out my engine choice, making any adjustments or alterations I want in the aircraft itself, etc. I need to know dimensions of the instrument panels so I can plan that out, dimensions of the firewall and fuselage so I can plan the most Tiger Moth-y engine installation, etc. The plans will cost me $400 but that will then be credited to me when I purchase my first set of parts.
Sorry for the long hiatus, had to deal with a family medical emergency. But this project was on my mind the whole time. Mostly I’m still stuck on the engine, and wondering what it would look like with that Honda motor installed. It’s the closest fit that’s readily available in that it’s a vertical 4-cylinder, but rather than mounting the prop at the top it mounts it in the middle. I decided I needed to visualize what that might look like.
It may even need to be a little more drastic than this, but I won’t know until I REALLY get serious and order the plans for the kit so I have exact dimensions to work with. While it’s definitely not the traditional Tiger Moth “face,” it really doesn’t look too bad to me. I think it could be done well, and look “right.” (this sketch really doesn’t, but it’s just a quick mock-up) So that has me really leaning towards going with the Honda option.
During my “break” I also got to visit a de Havilland Chipmunk undergoing restoration. It would have originally had a Gypsy Major engine as well, but long ago it was modified to accept an IO-540, which is a horizontally opposed 6-cylinder motor, much like the Corvair engine I was thinking about for this project. In order to accommodate the engine, the entire nose of the Chipmunk had to be changed, and a new fiberglass (or, in this case, composite) cowling fitted. It’s a great engine, performs well, but I have a hard time getting past the looks. I like that traditional de Havilland Gypsy Major “face.”