I now have about 28 hours in three separate Sportsman planes and about 800 hours in GlaStars, so I feel I am in a pretty good position to critically compare the similarities and the differences of the two related aircraft.
Cruise Speed: I would rate the overall top speed of the two aircraft as fairly even with the same powerplant. It seems there may be a slight edge to the Sportsman, but it is slight if real. With my taildragger GlaStar with an IO-360F1A6, I could reliably count on 135 knots (slightly over 150 mph) in cruise. With my Taildragger Sportsman with an O-360-A1F6 I am getting just slightly better (about 137 knots).
This could be due to the fact that my data only includes new engine data for the Sportsman, but included total time data (0-800 hours) for the GlaStar. I also have an 80-inch prop on the Sportsman and had a 72 inch prop on the GlaStar. The Sportsman aircraft with the IO-390 clearly walks away from the smaller engines on either aircraft by reportedly close to 10 knots.
Slow speed and stall: These speeds are also nearly identical. The Sportsman, however, gets a definite edge due to the fact that it has bigger flaps that keep the speed down better during steep descents.
With the GlaStar, I needed to vigorously slip the plane to keep it from over-speeding on the necessary steep descent into my ranch whereas the Sportsman only needs full flaps and a straight approach. As a result of the better drag of the flaps, the power necessary to maintain level flight with full flaps is greater. The climbout with half flaps, however, is the same as nearly as I am able to determine.
With the longer prop, I am getting a better slow speed climb with the Sportsman, but I suspect it is strictly due to prop differences.
The control harmony is clearly better with the Sportsman than the un-modified GlaStar. In the GlaStar, the ailerons are very heavy compared to the elevator and the rudder.
If the GlaStar has the added servo tab (or tabs) it is very close, but for some reason on the planes that I have flown, there is still a slight edge to the Sportsman. The unmodified Sportsman ailerons are very smooth, predictable and easy.
The flap control is very different with the two planes.
On the GlaStar the flap lever is increasingly difficult to pull with increasing airspeed. It is easy enough at the lower speeds, but can be quite difficult at the top end of the flap speed range. I found this to be a good way to manually determine and control my airspeed when keeping my eyes out the window for other planes in the pattern. My 110 pound (dripping wet) daughter, however, had a difficult time pulling the flaps at the top end of the flap airspeed and had to take her hand off the stick to pull with both hands. The Sportsman flaps are really easy at all airspeeds and can be done with two fingers. This could conceivably be a bad thing, since you can not tell just by feel if you are trying to put them down well above flap speeds. Overall, however, I would rate the Sportsman flap system as superior.
The Sportsman is a very clear and big winner here. The method of fairing the gear makes the gear stiffer, so the ‘bouncing on down the runway’ problem with the taildragger is nearly nonexistent. The weight distribution of the Sportsman gives much better flare authority – even with the heavier engine-prop combinations that have become the norm over the last few years. It is literally possible to fly down the runway with the tailwheel on the ground and the main gear still flying – even though this is actually a higher angle of attack due to the taller main gear. The need for gap seals of the elevator or vortex generators on the horizontal stabilizer is completely gone. With the nosewheel, they are both easy and forgiving, but the stiffer gear and improved flare authority helps here as well.
Weight and Balance and Loading
The Sportsman clearly wins for carrying capacity.
With a maximum gross weight of 2350 lb compared to 1950 for the GlaStar, it ends up with an increased carrying capacity of around 250-300 pounds. Because the structure is heavier than the GlaStar, the useful carrying capacity does not increase by quite as much as the maximum gross weight increase.
The weight and balance limitations favor the GlaStar, however, in the configuration that I had in each plane. Since I put an O-360 with a constant speed prop in each plane, I had a far forward static C.G. in the GlaStar. The result was that as long as I could get it in the rear of the plane, the plane was probably going to be fine on C.G.
With the same engine and prop on the Sportsman, I am much closer to the middle of the C.G. envelope with my 2 batteries behind bulkhead A, and need to be more careful about loading considerations. In some scenarios, I will not be able to load the plane to even near the full maximum gross weight and still remain in the C.G envelope. While I have not done any calculations on the Sportsman with the IO-390 – particularly with the battery in the engine compartment, I would bet that this would not be nearly as much of a concern.
I would also suspect that if the C.G. were placed farther forward in such a setup, some of the flare authority and control gains as noted above might be lost. Why does everything have to be a tradeoff? It hardly seems fair.
There is a definite difference between the two planes in this aspect. The GlaStar has a lower instrument panel and in the stock configuration has smaller tires on the main gear, so the visibility over the nose is better with the GlaStar even in the tricycle gear configuration. There is even more difference with the Taildragger configuration. While the view over the nose in both planes is better than almost all other taildraggers, it is superb with the GlaStar. Side view and up view are the same and are much better than most high wing airplanes.
Ease of Entry in the Front Two Seats
In this area, the GlaStar has a clear advantage. The Sportsman sits higher due to the bigger wheels and tires and the result is a more difficult entry in the front two seats. My method for entering is to lift my right foot into the foot well and then sit down on the seat. I then swing my outboard foot into the plane and then lift my inboard foot over the stick. This is definitely more difficult (but I can still do it well) with the increased height of the Sportsman.
Baggage Access and Rear Seat Entry
In this area the Sportsman has a clear advantage – especially in the taildragger. The rear door is a real benefit and when the tail is sitting on the ground, the entry is downright easy. You just sit down and then swing your legs in.
Baggage is easily placed through the rear door in the foot wells for the rear seat or on the rear seat, or behind the rear seat depending on loading and passenger needs.
Trying to get the rear passenger into the jump seat of the GlaStar (if you have a rear seat – as I did) is often downright funny. Teenagers do it without much difficulty, but the gyrations necessary to get in are fun to watch. I used to fly with our local airport octogenarian, Margie, in the rear seat and this could be an ordeal. We needed a stool to get her up to the front doors and it took quite a while to get her in and settled. At times we resorted to having three people pick her up like a roll of carpet and literally stuff her into the rear seat through the baggage door. Our standing joke about this was that we were smuggling grandmothers.
Wing Folding and Trailering
The GlaStar wins in this category. The narrower rear fuselage allows the wings to be folded closer together and the wing clears the top of the fuselage a lot better. The newer Sportsman design has a bigger single removable wing fold panel, but the older models had a separate plate that had to be removed to accommodate the flap tracks. They fit equally well and maneuver equally on a trailer.
Building and Parts Fit and Finish
This is another area where the Sportsman really wins. The company has fixed a lot of the annoying problems with the building of the GlaStar and incorporated them into an easier and better fitting process with the Sportsman. I surmise a large part of this was due to the fact that they were much more involved with the building of the Sportsman and had to put up with the frustrations themselves, thus leading to the desire for a good fix. Whatever the motivation, however, the result is much more pleasurable.
The only area that was (in a way) better with the GlaStar was the ability to use the glossy smooth gelcoat as a finish instead of needing to paint the entire plane. The advantage of the Sportsman in this regard is a better type of resin that although it requires paint, lets you paint with darker colors because it is less heat sensitive.
The Sportsman clearly wins when all things are considered (especially with the increased useful load) and the company has made good improvements on a great design.
I do not think, however, the incremental benefits of the Sportsman over the GlaStar are great enough (in hindsight) to have gone through the trouble to sell my GlaStar and build the Sportsman if the only consideration was the incremental benefits of the design. In my case, the need to experiment, and the fun of building, and the fun of something new, and the increased value of the Sportsman was clearly worth it.
Although it would have been nice to have kept the GlaStar line in production forever, in the real world of limited resources and the need to concentrate on making fewer designs more successful, the company made the right choice.