Grass/tarmac differences

[Grim Reaper 14]

Just got the old ppl, never 'done' grass, planning on getting to Sywell, anticipating some instructor time beforehand, a heads up on a few differences would be nice though please!:D

[QDMQDMQDM]

Grass is much nicer and friendlier than tarmac. It's what aeroplanes were made to fly from. ;)

Watch out for bumps, keep the stick further back than you do on tarmac and obviously if it's a tailwheel aircraft keep it right back all the time. Also, be careful of sliding on wet grass when braking (need to brake less on grass anyway) and be very careful of taking off from long wet grass with a load on.

Otherwise, enjoy.

QDM

[Ludwig]

Rolling resistance mainly. Grass tends to slow you down more quickly but also holds you back a bit on take off. You should factor into your performance numbers the fact that on grass you will need longer to get airbourne. Good smooth flat dry short grass will probably make very little difference; long wet bumpy grass can make loads of difference. I recall there are some official factors figures for these surfaces, but cannot remember where to find them; anyone know?

Also braking on wet grass can mean the wheels lock and you just skid along gracefully. It is difficult to remember cadence braking when you are skidding off the end of a runway.

Grass tends to be a bit more forgiving in cross wind not quite perfect landing I find.

Otherwise its the same as any other surface.

Sywell is a bit bumpy so beware of prop tip clearance and tailwheel fatigue, but other than that you should be able to get any GA a/c in an out without much trouble. If it is muddy the mud can get into the wheel bays of retractables and clog up he micro switches giving spurious gear warnings.

It can be good fun watching people who usually operate on 4,000metre tarmac landing on the shorter runways, down hill; still there is a fence to arrest the travel:D

[Lowtimer]

GR14,

Sywell is a fine airfield at which you will see a lot of traffic, not all of it working at standard light aircraft speeds. The airfield is extensively used by microlights and helicopters as well as conventional light aircraft, Cubs and Tiger Moths, high performance aerobatic machines, and the occasional warbird. Obviously a good lookout is required along with some mental flexibility. Quite a bit of overtaking goes on in the circuit but in general people do so with regard to the needs of other airspace users.

Standard overhead joins are the norm, and very useful for the opportunity they give you to view the overall circuit picture before you slot in on cross-wind.

The three grass runways are generally in good nick. As with all grass runways, however, they require some different considerations from hard surfaces. Take-off and landing, of you are only used to hard runways, can seem quite bumpy, and you need to keep the nosewheel well protected. Taking off, consider using part flap if your POH allows this. I always use two notches on grass in a PA-28, one notch in a C152.

On hard runways you are probably accustomed to nailing the centreline. On grass, in contrast, aim one side or the other. The centreline is what takes most of the hammer and gets bumpiest, and most rutted. Plus, the runways are much wider than you are probably used to. Don't let this sucker you into a false picture - remember the extra width and allow for it in your perspective view.

The threshold of 25 is particular is a bit bumpy for the first 50 meters and slopes down quite strongly to the left. Watch out for this, and go around if you have any doubts or start to bounce badly.

Also bear in mind the usual performance issues associated with wet and dry grass on braking action and take off accelleration. In particular don't brake too harshly on damp or wet grass otherwise you may skid.

Enjoy your trip in, though - it's a good place to visit.

[distaff_beancounter]

Much as I hate to disagree with 3xQDM :D

Some aircraft, such as taildraggers, were designed for grass runways & are MUCH easier to land on grass, than on a hard surface.

On the other hand, some modern tricycle aircraft, are much more suited to tarmac. In general, I have also found some high-winged A/c, C152/C17/C182, easier on grass than low-winged A/c.

You also need to consider what the undercarriage is made of. I have always found that PA28s with conventional oleos, will settle more easily on grass landings, than say the AA5s that have bonded (laminated?) glass fibre, main gear arms. This ensures that AA5s bounce nicely on any grass runway, that is not like a billiard table.:D

Unless both the pilot and the aircraft are very good at grass landings, it is prudent to add on a large safety margin, to the landing distance, & take-of run. eg I am happy to land an AA5 on 400m of tarmac, but not less than 600m of grass. But the Citabria (high-winged taildragger) that I used to fly, would both land & take-off in about 50m, so with a safety margin, I was happy to take it into a grass strip of 350m

Grim Reaper 14 . If you have not done any grass landings, you are being very wise getting some practice with an instructor. That is the only way to really understand the differneces to tarmac landings.

Although I do a fair number of grass landing every year, in assorted PA28s, AA5s & GA7s(twin), I will probably go to the Sywell Fly-in by car, as I do not like the sound of its grass runways. I will wait for the tarmac, next year :(

OK..... So I am a wimp! BUT... I am a live wimp :D

[Evo7]

Having learned at a soggy grass field in Sussex, I find tarmac kind of wierd... :)

[AerBabe]

Sywell's no real problem... don't let these experts put you off ;)
I went in there a few times when training, and have been back once since. It's not the nicest of grass strips, but it's long, and wide :)

[distaff_beancounter]

Grim Reaper 14

There is an AIC (I can't remember which one) that gives a table of factors to apply to the aircraft's take off & landing distances, to allow for such things as wet grass (which can add 30% to the take-off distance).

This table is also on the back of Safety Sense 7 - General Aviation - Aeroplane Performance

It is also repeated in LASORS 2002, Pages 487-494

All well worth reading, as it encourages us to consider such things as slope, grass/tarmac, wet/dry, runway length, etc, before committing ourselves to a visit to that airfield.

Have fun with the grass landings :)

[SlipSlider]

Some good points made here, but one that is often overlooked is that as grass runways are often quite bumpy, make sure you forewarn your pax that your usual smooth landing may be slightly less smooth ...... ask them to imagine driving at 60 mph on a motorway to the same 60 mph on a grass field.

Also, make sure you do have the runway positively identified; unlike a hard runway which usually stands out extremely well, a grass runway can sometimes be difficult to distinguish from adjacent areas like a taxiway, or perhaps a recently cut sileage area. An overhead join first-time at a grass field is a good start, but if in doubt, go around from final and have a good look as you do so.

Hope you have a good trip
Slip

[sennadog]

The only thing that I can add is for taxiying. Make sure that you hold the stick back to avoid prop strike and as everyone else has pointed out they are bumpier than tarmac airfields so the best advice I can offer is to taxi far slower than you normally do to avoid banging the aircraft about too much. If you see a depression or bump then I find that it is best to taxi over it at an angle, again mainly to avoid the possibilty of a prop strike.

Regarding Sywell, my advice would be to get there early before I do and watch my landings in the Katana as this will make you feel much better about your efforts!:D