I’m not going to participate in the “400m grass strip” debate, but from personal experience I would vote a C210 as number one for a family plane. Especially the post-68 (or 70? not sure) models that have the larger baggage compartment and true six seats. These are simply the most versatile of SEPs unless you regularly need to go into rough strips, then it’s a 206/207.
As for twins: these days I mostly fly Barons (BE55) and if you apply safety factors you quickly realize that while great traveling machines, they are limited in the airfields they can (safely) use.
172driver wrote:
the “400m grass strip” debate
Talking on family plane my measure is not ‘the 400m gras strip’ for take off and landing, but just risk related the typical field length of a farmers crop field in case something goes wrong. The odds to get safe to the ground without hitting something is vastly increasing if you only need 200m. Does anybody happen to know the typical length of a crop field in Europe – could be a parameter for selecting?
I have used 700m grass before rejecting in C172S (180hp) with family: Abbeville grass has 1000m but was very wet that afternoon (pavement 1250m was NOTAMed not available, I still went inspecting it and took off on paved runway on the second attempt, bellow picture of conditions 20min before takeoff), you could argue it’s on edge for taking wife and kid in instrument conditions: it was very sunny in Baie de Somme the morning, the grass was dry the morning then isolated heavy showers afternoon grass and was probably unusable for a full week due to water logging…
With that in mind, I am very worried when I hear about 500m grass capability in IFR twin aircraft: it’s unforgiving when you consider weather: especially on wet grass and pressure to get there…
I have flown 2pob Mooney in Clacton & Pittsford in winters, there was literally zero room of error as measured by the distance between pilot teeth, I would never go there fully loaded with passengers !
Here are conditions in Abbeville (I can’t upload a video), it was sunny afterward for takeoff with a factor of 400% on takeoff roll 
Takeoff roll on grass is probably published by test pilots in during certification but those POH numbers are useless, it’s always somewhere between 400m and infinity depending on complex factors, even performance for a given (day, runway, aircraft, pilot) can’t be replicated in consistent fashion !
@172driver it concerns me when you say, quite rightly, that you add in a load of safety factors to the POH performance figures in a BE55.
Does that mean that you don’t take into account the same safety add ons in an SEP?
Does that mean that you don’t take into account the same safety add ons in an SEP?
I add Public Transport factors in MEP (the lady who rent it to me insist on that), it will be silly & daft not to do it, especially as the risk of SEP engine failures dwarfs the risks of crash on MEP takeoff…I rarely give a hoot about PT factors in SEP (I may fly POH numbers or even less, I even fly aircraft that have nothing published to start with)
I think the cost of getting it wrong or things going badly on twins is huge due to obvious physics from speed & weight: I am happy with 1% chance of crashing a C172, Cub or Microlight on the hedge during short takeoff (no issues with similar odds) but I think 0.00000001% is the threshold on Seneca
In theory, you can replicate POH short & soft field takeoff distance in single SEP & MEP but practically in twins you may need to “rotate” close or bellow Vmc (dragons live there), in the other hands, in singles rotating bellow Vs is not an issue as long as you get it to accelerate level, worst case you reject on the ground or bend it in the trees, it’s fine in Cubs you will walk away from it on sensible speeds keeping wing level
I think people who fly twins tend to have less risk appetite than those flying short strips in singles, however, I would not compare the two on missions to short & soft fields, the outcomes are very differents!
Ibra wrote:
I am happy with 1% chance of crashing a C172, Cub or Microlight on the hedge during short takeoff…but not with the family, are you?
(BTW Cub or microlight do not fit the bill as family airplanes)
but not with the family, are you?
Definetly not the kind of thing you do when doing family flying (as start you can’t hide your face expressions), also with family people fly MTOW (+/-30kg rounding errors), I personally have used 900m on few “family flights” in SEP: night, gusty, hot, waterlogged, visbility…I rarely used more than 600m on my own (even in twins)
I must admit that I tend to.go through the same add on performance whether I am flying a twin or an SEP or ULM. If t/o is on grass I add a bit, if the grass is long or wet I add a bit more etc.
In a twin I normally rotate above Vmca, in an SEP I rotate at Vr.
Either way I analyse the decisions and what I would do “what if?”. Eg short field take off POH calls for 1 notch of flap. But what advantage does the flap give me in a particular case.
Twin or SEP any problem on take off roll immediately means aborting take off.
The difference on wet grass means I might slide further on the twin, but then again I will be ready to rotate at an earlier point on the runway maybe 100m earlier or so etc etc etc. Normally in a twin its a no flap take off.
What I don’t understand is why people seem to think that one should analyse less on an SEP than on a twin.
What I don’t understand is why people seem to think that one should analyse less on an SEP than on a twin.
Some ATO do that as well: they operate SEP on NCO against raw POH while they operate MEP on POH with margins plus CAT/PT add-ons
Maybe bad safety culture in singles and very conservative safety in twins? ideally, everyone should put those 1.15, 1.25, 1.41 factors on top as well as requiring balanced lengths? this means you will never fly under 600m pavement even in C172
I am inclined to fly C172 in 600m pavement with no issues, day & night, every weight and all weather, I would never fly twins in that…
