evaluating unpaved strips

I'm in Phase 1 of a 7A and would eventually love to fly into some grass strips. I have very little experience on grass/gravel but understand that there are some beautiful and appropriate strips and some ROUGH and inappropriate strips.

I would love to learn some tips from experienced grass/gravel folks on techniques to evaluate if a strip is appropriate for operations with a 7A. I know that technique is hugely important, as is practice and experience, but I also know that there are strips that, no matter how good you are, you're better off not landing there!

How do you tell? If there's been rain, how do you tell if it's well drained? What are your techniques for "dragging" the strip and what are you looking for from the air? How low do you need to be to evaluate these things?

Thanks!

Jeremy Constant

P.S. Please, with respect, no rehash of Nose Gear collapse discussions

There's no good answer, Jeremy....

..unless you know someone who has landed there, or the owner. It's very hard to 'drag' the strip, even from 15-20 feet, as I often do when we're spraying off a remote field. There's just no way to tell how firm it is.

Our EAA field was pretty wet last Saturday, so I drove the 30 miles instead of flying. I watched an RV-7 and a Pitts land, throwing water everywhere and was glad I left the -10 at home.

Consider rainy weather at the strip you're thinking of going to, as we did, and let that help you decide. The EAA strip had over an inch the day before.

Best,

What Pierre said,
Calling ahead to someone familiar with the strip is the best way to gauge its suitability. It's just not feasible to fly over and determine how smooth or rough the strip is. Even then, some strips may be suitable one day and not suitable the next. I once got a 206 stuck in the turf at a strip I regularly went into, because it had rained too much the day prior. If you're unsure about a strip, and don't see lots of planes parked on it, you will probably want to make a call or two before attempting a landing there.

Okay...check the recency of rain, call ahead if you can and don't be the landing strip test pilot -- look for or talk to others that are/were there before you that day.

I guess the guideline is that there are more appropriate planes to do the first test of the day!

Thanks guys

Jeremy

One other consideration, Jeremy.....

...is whether or not you have a CS prop or a lighter FP. It's difficult to hold the nose up very long with no baggage and a CS prop, making the go-no-go decision even more important. I try to not land with a lot of fuel (forward CG)
on an unknown strip as well, to hold the nosewheel off longer.

BTW, you have another 1" of clearance if you complied with the nosegear service letter and later fork. That, and be sure it's well inflated for the most clearance.

Best,

CG

Funny you should mention CG Pierre -- during my Phase 1, I've noticed that with just me (no ballast...er transition training instructor) the nose-wheel comes down much more quickly after landing than with a right-seater in the plane. The last landing I did yesterday during testing, I used only half-flaps and that certainly helps, and I'm looking forward to the CG testing. I definitely understand what you're getting at...I wouldn't want to land on a muddy strip with reduced ability to keep the nose off.

I have a WhirlWind 200RV constant speed, so it's between the weight of a nice wood or Catto prop and a heavy Hartzell constant speed. In my W & B I've got 310lbs on the nose, empty.

I have the new nose gear leg, keep my tire inflated at 35 to 40lbs and when I put the wheel pant on, I'm thinking of putting a flox brace between the bottom-forward part of the wheel pant and the infamous nut. It will follow the contour of the bottom forward portion and I am hoping it will act like a skid, in the event that the bottom of the wheel pant comes in contact with the ground.

Thanks for your observations and thoughts!

Jeremy

Calling ahead

No matter what you do in advance you will not have certainty until you actually land on the strip. Calling ahead is wise but only if you ask enough questions.

I wanted to use a grass strip that had camping cabins so I called the owner and asked about the strip. He assured me it was fine, not rough, that he regularly used it himself and many other pilots did also. This was early in my time in my 6A. When I landed it was the most jarring landing I have ever had, speed bumps all down the length of the runway, like an oldfashioned washboard. Take-off was worse. It was not a good experience. While camped there I saw the owner take off in his plane: a Piper Cub with tundra tires. No wonder he was OK. but not me.

Now I won't land at a grass strip until I have physically walked it prior, or a fellow RV'r has landed ahead of me and given me a report.

List airports under state forums

Not sure if this is a good idea, but a list of grass airports that are known to have a good landing surface might be nice to have on this forum. I know rain can change the surface but if there are grass strips that RVs routinely use one might list them under the state forums with how well they worked out.

Just an thought. I am not flying yet but love to camp and backpack, having reports from others who have done ahead would be nice pre-flight information. With the sensitivity of the A models having a report from an RV driver would be way better than anything else you could get.

Cheers

We normally teach glider pilots the "Seven Ss" about selecting off-field landing sites. Although we're talking about something a bit different here, they might be useful. Written by Dean Carswell and copied from the SSA:

Surface wind - strength and direction - assess direction by drift, smoke, large flags, ripples and wind shadow on water, cloud shadows ? but be wary as the surface wind may not be the same as at cloud height. Unless wind very light, plan to land with substantial headwind component. Consider topography of approach and landing area and possible effect on wind. Wind in valleys may be different from hilltops or at glider altitude.

Size - check for adequate length: minimum 7-800 feet, comfortable 1,000 - 1,500 feet; however requirements vary depending on glider type, wind speed, slope, etc. Assessment of apparent size may be colored by size of surrounding fields. Small fields make adequate field look large, large fields make adequate field look small. [2 lane roads are 25 - 30 feet wide, typical small houses 50 feet long, wooden phone and power poles are usually 150 - 200 feet apart, football fields 300 feet long.]

Shape - if greatest length has a strong crosswind and little headwind component, determine if use of the width (into the wind) is better - depends on wind strength.

Slope - any visible slope unacceptable - most easily identified if viewed from a distance, not overhead; darker areas are probably wetter, and thus lower; if slope is apparent from surrounding topography and no flat alternatives available, plan to land uphill. Uphill landing requires more pitch-up in the flare, thus 5 - 10 kts more airspeed is needed. Landing uphill also gives an optical illusion of the glider being higher than it actually is. This risks an undershoot, and can be countered by aiming to land a little deeper into the field.

Surface - adequate and clear of obstructions - requires familiarity with crops, seasons [planning ahead]; you need to be familiar with the crops in the area you are proposing to fly, and at the relevant time in the growing season. Land parallel to rows/furrows. Generally crops of lighter color are better; but watch out for straw colored corn stalks, which is much too high for a safe landing. Check for fences, hay bales, ditches, irrigation equipment etc. [Exercise - practice picking fields from the air, making an evaluation of them, then going and actually walking them to check out your assessment.]

Surroundings - obstructions on approach [buildings, trees, cables (look for poles, not wires), etc.] - reduce effective field length by 10 times obstruction height. For example, a 30 foot tree on the approach boundary of the chosen field will make the first 300 feet of the field unavailable for landing. Large obstructions can generate severe turbulence, especially on the downwind side.

Stock (livestock) - avoid fields with animals, if possible.

TODR

unpaved ops

Jeremy,
another thing in line with the 'tundra-tire' comment, our darn 5.00x5 tires are going to sink into soft ground like a fully loaded wheelbarrow. There's very little flotation there; ditto the nosewheel. I can't even get out of my parking spot after a rain, imagine the energy and speed of landing or takeoff ( attempted!)

so all the info about who has flown there, is moot unless you know exactly what aircraft and weights etc.

second, does your insurance cover private or unpaved strips? might be worth looking into.

I have limited experience, but I'll bet that most of the grass strip guys have the benefit of operating off the same piece of turf a hundred times a year, so by trial and error, they learn how the length of grass and rain each affect the rolling resistance, and thus runway length requirements, etc.
Another strip a mile away, with different soil, sod, drainage will be different.

Cows Blow Grass.... that's a vivid picture, no?

I enjoyed Art Lazarinni's book a few years ago. I won't give away what "Cows Blow Grass" stands for, enjoy the book yourself! A fun read that discusses your very question, how do I know it is safe to land here.

Nearby weather stations and other intel

This webpage is part of my preflight to some unpaved strips. There would likely be a similar resource if you are outside the PNW.

http://www.wrh.noaa.gov/mso/newrgl.php

Click on a weather station(s) nearby your intended destination. Some but not all have precip history, wind, humidity and temperature data available. Having data of this type can often allow a good call on field firmness from hundreds of miles away. Of course, one has to consider distance from weather station to the strip, elevation differences, exposure differences, and etc.

Shortfield.com has occasion pireps

Faa notams sometimes list field conditions

In Idaho, we've got commercial operators going into these strips, so getting on good terms with pilots or dispatch, can be a great way to get a current pirep.

Landing on Grass

I've found that braking action on wet grass can be similar to landing on ice! If it has recently rained, don't count on a real short landing roll!

Also, associated with grass fields is the possibility of wildlife! Not just above ground, but watch out for ground chuck holes!

Danger all around!