Actually, I am going to suggest this very thing to our farmer. The 'runway' (ha ha) strip already has a down slope and I thought that the most cost effective drainage solution would be to 'ditch' either side of the runway - the only problem with this is that the mown strip itself is only about 3 metres wide so good drainage will be at the price of very accurate future landings or risk of a bent undercarriage

Right, I have a quote back. £4,000 +VAT for a 620 ft by 32 ft runway. It's been stressed to me that this does not include fitting (but it was worth asking...)

That comes on a total of 40 rolls (25m length by 2m wide). So this means we're talking 5 rolls wide, with eight sets of rolls down the length of the runway.

For more details:

Sarah Davies
McArthur Group
01772 556042

(This contact is based in Preston, but they have branches around the country)

T.

I've just looked again at your figures, and I think (correct me if I'm wrong here), if they're 20x2m rolls, then you need 40 of them (I think there's been a feet to metres problem here). So that's 40 x £195, which is a reasonable £7,800.

Both figures are in the same order of magnitude, I can only assume that McArthur has quoted us on the bulk order amount.

That previous price did seem a bit high, since I have recently come across a case where re-tarmacing a 600m+ runway would have cost "only" £60k or so.

I suppose there is a reasonable amount of downtime after preparing a grass runway (or even retarmacing it)?

Just picked up on this thread. IO540 is quite right that lifting the nose wheel early in 'sticky' conditions reduces wheel drag. This is not only by not ploughing a furrow through the mire with the nose wheel, but even early in the run, some lift will be obtained from the increased AoA, reducing the drag of the mains.
I learnt on a grass strip in a C150, and on my 4th or 5th solo take off, it got to about 30kts, when it would go no faster ploughing through the mud. Feeling that I could drive it like that to end of the strip, instinct caused me to jerk the stick back momentarily, which lifted me an inch or so to be aquaplaning on top of the mud, when I then accelerated normally to lift off.

A word of warning. Even on a hard runway, lifting the nose early also increases drag from the increased AoA and angled fuselage, so acceleration will be slower, and take off run greater. As IO says, this can be much better than the even more reduced acceleration caused by ploughing through mud.

However risks are that you will get off early in ground effect, without enough power to go anywhere whilst on the back side of the drag curve (not much likelihood in a TB20!), or the oncoming hedge at the end causes you to pull back even further, which prevents you getting airborne at all. AAIB reports have both of these cases. Several years ago, an aircraft trying to depart Bodmin lifted its nose early, finished up scraping its tail on the ground, failing to get off as it went into the hedge.

Muddy strips almost preclude confidence in take off run calculations, especially as its going to be different at various point along the strip.

MikeJ

Yes, I think there is a lot of misconceptions going around takeoff techniques and how they relate to the figures in the POH.

The POH figure is for a dry hard runway, unless otherwise stated.

A "soft field" takeoff is going to use a lot more runway than the hard runway figure. Even doing a soft field takeoff on a hard runway (pointless except when doing an FAA checkride perhaps) will use a lot more runway because of the extra elevator drag, acting like a giant air brake.

I suppose that in a low powered type (e.g. a C150) a soft field takeoff may be the only way to get off the ground so one cannot even do a comparison with a normal takeoff off the same muddy grass, but the resulting takeoff run is going to bear little resemblance to what is in the POH :)

I did a soft field takeoff the other day in the TB20, off a hard runway, and the run, including the bit in the ground effect, was about 600m. Whereas a normal takeoff is about 350m, both cases about 10% below MTOW. It was staggering how much extra drag there is due to the elevator being all the way back. A soft field takeoff may keep the mud collection down but that's not much use if you don't get off the runway. And this is a TB20 which has loads of power.

Those flyers that get handed out about grass taking 30% more than tarmac, etc, are meaningless in so many cases, IMHO.

I once had the occasion to take 4 people up in a C-172 from a sand strip. First had a talk with the local CFI/operator to see if this was at all possible. His advice was not to keep the wheel all the way back once rolling.

Taxi took considerable power. Picked a point where I would abort if not airborne -- in the sand, 100 yards was plenty;)

Full power, wheel all the way back got me to about 40 kt and no more; so, eased off on the wheel. The a/c accelerated and I lifted off, built speed in ground effect and climbed away:ok:

The trick is to keep the nose wheel just clear of the ground once you have 30 kt or so as you now have lift taking the load off the mains.

Blasting all the way down a soft runway with the wheel/stick all the way back can add you to the statistics as before mentioned:uhoh:

Our home airfield stayed drained and perfectly servicable.

but....

CAVOK this morning - only on this side of the Chilterns.

Freezing fog on t'other side of the hills, all the way across Oxfordshire it seems.

Grounded. Grrrrrr! :ugh:

Shortstripper - haven't seen a response to your query, but it seems to me that iff Goodwood has an A/G service, it is you who are in charge, and you can, theoretically, do what you want. They might not invite you back if you do something silly, but taking off half way down a runway in a STOL aircraft wouldn't really constitute that.

If it is AFIS, they have the power to give instructions to ground movements (I think), but if you say you are lining up for take-off and then take off, you can do it, because they have no authority to grant you approval for take-off or refuse it.

Why not have a word with the aerodrome manager? They are probably concerned about noise, and you might be able to discuss the whole thing and reach a common sense answer (although in my experience, common sense is not common at airports!)

What a fantastic 'solution' - and even if it in't - what a great idea anyway.

Just heard that one of the guys at a local Club that is notorious for getting claggy and saturated has invested in a racing hovercraft which he bombs up and down the runway when it is completely sodden:

1) It's great fun
2) It doesn't damage the surface
3) Allegedly it dries the surface out

Ebay - here I come............................................

Shortstripper wrote:
Hi SS. I was intrigued by this as I have seen occasional mid-point departures, including a friend visiting in a Rans S6 who was not keen to taxi downwind to the hold in a 20 knot breeze. Also the FISOs at Gwd are an excellent bunch, always helpful, and always friendly! :ok:
So, I spoke with the FISO yesterday, and he recalled the occasion immediately .... it seems that on that particular day it was felt that the threshold was actually preferable being less wet than the area where you suggested departing from; apparently there is a tendency to standing water near the runway intersection. Agree or not, that was the reason, and with the best of intentions.
Regards
Slip

Fair enough!

I'm familiar with Goodwood and wasn't near the point you say, however, in a drafty open cockpit it's not always possible to see the bigger picture :)

SS

"I spoke with the FISO yesterday, and he recalled the occasion immediately .... it seems that on that particular day it was felt that the threshold was actually preferable being less wet than the area where you suggested departing from; apparently there is a tendency to standing water near the runway intersection. Agree or not, that was the reason, and with the best of intentions."
Slip, reassure me you were merely talking to the FISO and not airing that wonderful machine?
This isn't thread drift because in this wind, one doesn't need a runway...:sad:

Water-logging is not a problem with our 1000m strip - it's the wild boar digging holes and ruts...

We recently had to withdraw our (tarmac)cross runway due to significant subsidence which would not have been cost effective to re instate.
However, I am convinced that the land adjacent to it is more than capable of supporting a 800 to 1000m grass runway.
I am aware of the CAA (CAP168) requirements, but any support for this from operators and how I could present this as a low cost alternative for G/A at our place would be gratefully recieved.
Ta.
niknak.

ChampChump wrote:
Indeed I was merely talking to the FISO! I was all set to meet with others at Henstridge, but the cloudbase at Gwd was around <500' all day. I hung around to see if a short local might be on, but sadly not. That's it for 2006 it would seem.

Back to the thread ... maybe the threshold is in any case the best place to start from on a muddy runway, especially in a stol aeroplane, as most touchdowns (thumpdowns?) which damage the surface are much further down the runway! :)

Slip

Aha the Northern Clay- just digging in some horse manure in my quagmire just as we speak.

I seem to think Bartons strips overly a massive bed of cinders, so I guess things could be a lot worse.

In my experience, things start to drastically improve as soon as the shoots of spring appear.:)