Robertson STOL handling characteristics
 

I have heard that RSTOL makes the aircraft less responsive in the landing configuration and gives it a mushy feel? What do you think? Is the STOL performance worth it?

Have flown one on occasion and I think it's a very legitimate system. It has to be flown knowing the characteristics of the aircraft in full flap configuration but really full flaps do not have to be used all the time. I think using 1/3 flaps for 95% of the ops is fine. Not sure I would seek one with Rstol unless I had the reason to really have the mod. Although when you do a Vref it does add $10k to the value of the plane

I've flown a straight Skymaster, a Horton, and a Robertson. I own a Robertson.

The Robertson is a little more "mushy" with flaps at 2/3 or full. It's fine, but noticeable. Once you get to 2/3 or full flaps and get behind the power curve the mushiness gets more pronounced. If you've never flown another Skymaster you might not care.

There's a little more cable friction in roll in the Robertson Skymaster.

The angle of attack required to get the full effect from the Robertson is stunning. It has the same wing area as all the others, so the only way to get more lift at slower speeds is more angle of attack, and you may not be comfortable with the extreme angles. You can't see the runway ahead at touchdown if you're using the max angle of attack available with the Robertson system - it really disappears. You have to be on your game to keep it straight in a crosswind if you're going for max performance. The manual says the mod is "...for use by the experienced pilot when emergency conditions on austere fields require the utmost performance consistent with safety." Don't forget it's getting airborne waaaaay below SE climb speed - if you lose an engine on takeoff, you're still going to eat dirt if it happens below 100 mph. It's not magic.

At light loads the short distances used for ground roll on takeoff and landing are amazing - but you'll have the stall horn blaring on both. I'm still working on wringing the max performance out of my Robertson - it takes some changes in technique and increase in skill. The book max performance numbers are only achievable at the absolute edge of the envelope - you rotate at 50 mph, for example. The only way to liftoff at 50 mph is with a ridiculously high space-shuttle-launch deck angle that gives zero forward visibility.

There's not much point in me quoting distances since I'm usually light, and have been doing mostly high DA takeoffs and landings (8000 ft on average.) The "book" chart doesn't handle high DA numbers well. I just know I can get better (and more consistent.)

The flap extension speed is reduced on the Robertson (108 vs 120 mph.) If you're doing IFR work in crowded airspace you should realize that you'll have problems blending in and getting the speeds that low, and it's very easy to get behind the power curve once the flaps are 2/3 or more. I do approaches above flap speed and do no-flap landings if I'm mixed in with any traffic.

With the exception of the extra weight (20 lbs or so), slightly extra maintenance (more lube points, more moving parts) and the lower flap extension speed, you always have the option of "not using" the Robertson. Nobody's making you lift off at 50 mph. Sometimes I rotate at 70 - it depends on the takeoff.

I waited for one because I wanted as much margin as possible, and I wanted lower takeoff & landing speeds for rougher backcountry strips. For the average Skymaster pilot, I'd look for a Horton or buy the kit. You can still buy a Horton STC, you can't buy a Robertson STC.