Short runway and crosswind

[splash76]

Hi all,

First, I'm new to the forum and learning about the Sonex. I maybe moving to a location too far from the airport to drive and considering a economic way to use my commercial certificate on call with the company I was flying for before all this $h.*% happened in 2020. No telling when that will be. It's not really the distance that makes it a slow drive but the speed limit is constantly changing on a twisty road which is a mental drainage after about 1.5 hours. This would get old real fast doing. So, I considered the possibilities and thought about maybe an airpark while flying to the commercial airport. The property is on a mountain slope and was once owned by a pilot whom passed away 3 years ago. He had an ultra-lite he used to land/takeoff on the street until someone turned him in. The property needs to be grated to make runway rather than landing on the street. I don't know what kind of aircraft he had but willing to find out soon. It does get gusty up there on the mountain side so my question about the Sonex is {drum roll] ...How slippery and twitchy is the Sonex? What is a good safety margin for length of runway? And how about the cross wind component? Considering these conditions would the tail or tri gear Sonex, I have to have 2 seats so someone can enjoy the fun with me, be a good reliable choice? I'm a commercial pilot over 4,000 TT 600 floats and ... 1! yeah, one hour but maybe two of tail wheel time in a C140 if this means anything to your computations which I thank you now for.

[GraemeSmith]

All I can tell you is I've demonstrated 17 knots direct and steady X-Wind on a dry pavement in a Legacy Sonex - at which point the solid 5" tailwheel was on the point of losing adhesion. Three point landing (well pinning upwind main and tailwheel). I haven't found any advantage to using a wheel landing to cope with X-Wind and some disadvantage when sticking the tail at the end of the rollout if rudder authority is lost in a gust prior to sticking the tailwheel. In day to day flying I consider 11 knots to be a more sensible and sporty enough X-Wind on dry pavement.

My "I'm on my game" personal minimum for a firm short dry grass runway is 2,000ft for departure with no obstacles with one in the plane so about 950lb gross - 80hp Aerovee.

Others with far more Sonex time than me can probably add more wisdom than me.

[sonex1374]

I fly a Jabiru 3300 powered taildragger with acro ailerons/short flaps. I find that on a typical landing at my narrow paved runway I am down and stopped in about 1200-1500 ft (trees at both ends of the runway) of my 2500 ft available. The plane will land shorter, but you really have to manage your speed over the numbers to get it down and stopped as short as possible. I find that for most landings I tend to keep just a little more speed over the numbers as a hedge against the turbulence that frequently comes off the trees and hangars located close by the runway. It's a different story when the runway sits all by itself with no obstructions anywhere.

Crosswinds are where I stop and think. The Sonex is a lightweight airplane and will get blown around a bit in gusty conditions. Steady winds are manageable up to 15 mph crosswind, but gusty winds over 10 mph cross start to require more effort. For me personally, gusty at 15 starts to bring the sweat.

The last thing to consider is the value of clear approaches to the runway. The Sonex is slippery, and if you come in over trees then dive at the runway, you'll build speed and float down the runway. It doesn't have the drag available that a supercub has, and as a result obstructions at the end are more telling than the length of the runway. My minimum would be 1800 ft with clear approaches, and 2500 ft with obstructions.

Jeff

[splash76]

OK, it's strange that I keep seeing 250'-500' take off/landing distance in the performance specs everywhere. What am I reading wrong?

Fuel Capacity 30 Gallons
Engine Jabiru 120 hp
Empty Weight 620 lbs.
Range (1) 687 miles
Cruise Speed @ Sea Level 135 mph
Cruise Speed @ 8000 ft (TAS) 170 mph
T.O. Distance 250 ft
Landing Distance 500 ft
[/b]Service Ceiling (calculated) 23,000 ft
Utility Category
Gross Weight 1150 lbs
Useful Load 530 lbs
Rate of Climb 1000-1400 fpm

[sonex1374]

splash76,

My own Phase I performance testing showed a landing distance (no obstructions, no super-human technique) of 700 ft. That's the point that I could reasonably expect to be down and stopped on a clear approach, good speed control landing, with full flaps and a bit of braking. Some tries were shorter (500 ft), but this was a good average when taking out the extremes at each end. By comparison, add a 50 ft obstacle and simply due to the airspeed and climb/descent angle the landing distance increases to 1400 ft. It's worth noting that this wasn't an attempt to see how absolutely slow or short I could make it, just what a reasonably proficient pilot should expect. The plane can probably do better, and on a good day I might be able to as well.

For takeoff performance I use 500 ft for ground roll (based on relatively crude flight testing). Partly this is my technique: line up, slowly advance throttle over about 3 seconds (no holding the brakes), bring tail up, then rotate and climb away. Using a short field technique would shorten this, but I've never tried it. Not sure if I could see 250 ft, but maybe...

I think the Sonex specs listed are kinda like other POH and/or marketing figures - they are what's possible under ideal conditions. User outcomes will vary greatly on any given day. The Cirrus SR20 shows a book value of 800 ft takeoff roll, but no one flies them from cow pastures...

I've seen some really good Sonex pilots, and they can extract more performance from the plane than I can. I try to be realistic considering my abilities, and my own comfort factor is more limiting than the raw potential of the airplane.

Jeff

[tx_swordguy]

Splash I fly a jab 3300 powered sonex and have half the fuel you are listing and plan my fuel stops at 200 nm with 30ish min reserve. I cruise 125-135 Mph at 2650 rpm . My empty weight is closer to 700. The 200-500 ft TO LNDG numbers might be possible with a 15 mph head wind but not realistic especially with two on board. A grass strip with only fencing on the end at 1800 ft would be a doable day in day out strip. 2 up you might need to pick your days . Again that depends on obsticals. Xwind for me on grass easy up to 10-12. Pavement above that gets me puckering a bit. It’s doable and haven’t bent anything yet but doesn’t give me warm and fuzzy feelings. Jeff has flown all over and knows these planes well trust his judgement

[builderflyer]

splash76,

I've seen some really good Sonex pilots, and they can extract more performance from the plane than I can. I try to be realistic considering my abilities, and my own comfort factor is more limiting than the raw potential of the airplane.

Jeff

We should make a placard out of the above self-realization and put it on our panels to read before each flight. Well stated, Jeff.

Art,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,Jabiru 3300 #261