First, the commercial interest disclaimer—we are the Robin agents for the UK and Eire. We did, however, buy our first Robin for our own use several years before we became involved with CEAPR and Robin Aircraft! we now have about 900 hours on Robins and around 800 on the diesel variants.
Comment on the Robin in IMC thread: we fly our aircraft throughout the year, sometimes in dense and difficult IMC. Certainly a glass cockpit makes life massively easier (and an autopilot easier still, of course) but we have flown analogue models with no autopilot through solid IMC with 60 kt cross-winds for an hour or two at a time without the discomfort we have experienced in metal and, particularly, composite, airframes. Vibration damping and shock absorption are two of the many benefits of a wooden airframe, which, together with the relatively high wing loading of the Robin, certainly pays off in rough weather.
Regarding de-icing, as has been pointed out already, ‘de-icing’ is really only a buffer to get the aircraft through icing conditions. Flying a non-pressurised aircraft means you will tend to be flying in the weather, not above it. Even with oxygen the ceiling is limited to 16,500 feet. An electrical de-icing system is under consideration but has not been prioritised by the factory for several reasons including: first, safety: in a non-pressurised aircraft with a fixed undercarriage a de-icing system could just as easily get you into trouble as get you out of it; second weight and, therefore, reduced payload; third cost. We fly throughout the year and on the occasions where we have encountered icing the solution has been just to descend into warmer air, an expedient allowed by forward planning. I am not saying that a de-icing system would not have a place, just that, overall, the downsides are likely to outweigh the advantages for many, perhaps most, owners.
Regarding keeping Robin aircraft outside: It is a myth that the aircraft are unsuitable for this. Current Robins are effectively waterproof and the problem of cracks in the paintwork of the flying surfaces, potentially allowing ingress of moisture into the airframe, no longer exists. Even with older models, flying the aircraft regularly will keep it aired and should prevent problems. Any aircraft will rot if left outside, unused, for long periods and it will be the avionics that go first. Remember, Robins have no fatigue life and have a 20 year warranty on the aerostructure…
If anyone has questions or if anyone who is interested in purchasing a new aircraft would like to experience a modern Robin, then please just ask us. We shall be happy to accommodate you. And do please have a look at our FAQ’s at www.mistralaviation.co.uk.
Your post @Mistral raised a few questions:
together with the relatively high wing loading of the Robin, certainly pays off in rough weather.
I had a quick look online for some data on this. All are lbs per square foot of wing area, and there are variations between similar models:
Cessna 150 10.2
C172SP 14.7
DR400 15.8 (from here)
DA40 2004 17.4
SR22 G2 23.5
TB20/21 24.1
So a DR400 appears to be similar to a C172.
we have flown analogue models with no autopilot through solid IMC with 60 kt cross-winds
Enroute, an aircraft is not aware of the wind as far as its flying behaviour goes. Were you close to terrain?
in a non-pressurised aircraft with a fixed undercarriage a de-icing system could just as easily get you into trouble as get you out of it
Could you explain this?
Mistral wrote:
: in a non-pressurised aircraft with a fixed undercarriage a de-icing system could just as easily get you into trouble as get you out of it;
I can think of a few non-pressurised, fixed gear aircraft with turbos and de-icing , even FIKI, that do not seem to pose any particular concern in that respect.
And if the engine ceiling is FL165 like it is on the DR401, the risk of hypoxia is relatively limited with oxygen.
Peter wrote:
loading
Because of the washout at the lateral ends of the Robin wing, most of the lift in cruise is achieved by the inner section, giving a loading in this configuration of closer to 159 kg/m2. A Cessna 152 is said to be 49 kg/m2 and a Spitfire 158 kg/m2. The lateral portion of the Robin wing does most at higher angles of attack, contributing to climb performance and low speed stability, but contributing very little to lift in the cruise.
Peter wrote:
autopilot
My experience of flying through rain in cloud + strong winds = turbulence. And yes, for part of this route we were at low level under the London TMA.
Peter wrote:
aircraft
Electrical de-icing of the propellor, and wing and empanage leading edges, will maintain aerodynamics at least for a while (although ridges of ice have been known to build up behind the heated surfaces, disrupting airflow and lift), but ice will continue to accumulate on other, non-heated, surfaces, such as the fixed undercarriage. Eventually, the mass of accumulated ice may prevent the aircraft from climbing, trapping it in icing conditions or forcing it to descend.
Aviathor wrote:
DR401
My knowledge of portable oxygen systems is limited, but I should be concerned about how long the supply can be relied on, particularly on journeys where the options in the case of shortage may be very limited.
Mistral wrote:
My knowledge of portable oxygen systems is limited, but I should be concerned about how long the supply can be relied on, particularly on journeys where the options in the case of shortage may be very limited.
That is true also of fixed installations. That I why I stated that with a ceiling of FL165 the associated risk is low because hypoxia will not set in as quickly (you need to monitor your blood oxygen level when flying above FL100-120) you can rapidly reach a level where you do not need oxygen (provided you can given terrain below). It is a real concern at FL250.
Mistral wrote:
Because of the washout at the lateral ends of the Robin wing, most of the lift in cruise is achieved by the inner section, giving a loading in this configuration of closer to 159 kg/m2. A Cessna 152 is said to be 49 kg/m2 and a Spitfire 158 kg/m2. The lateral portion of the Robin wing does most at higher angles of attack, contributing to climb performance and low speed stability, but contributing very little to lift in the cruise
I think this is an extreme understanding of washout. It’s true that the inner portion of the wing has a hihger AoA and lifts more, but not to the exclusion of the outer wing lifting some. It would be intolerable to be dragging a large portion of wing through the air for cruise flight, which was not creating lift. An unsymmetrical airfoil will create some lift even at zero AoA.
I don’t know the washout in a Robin wing, but I can assure that all Cessna wings also have some washout. The ratio of lift to that are of the wing is probably very similar for both types.
The cranked wing with washout was a very clever design taking advantage of the construction materials. There may be a small winglet effect reducing lift dependant drag? I agree with Pilot_DAR, the outer wing portion is unlikely to be on a zero lift line in cruise and the wing is positively cambered – so zero lift line of incidence would need to be negative.
Pilot_DAR wrote:
I don’t know the washout in a Robin wing, but I can assure that all Cessna wings also have some washout. The ratio of lift to that are of the wing is probably very similar for both types.
Although I don’t think you have zero lift in cruise on the Robin-wing, I won’t bet on a similar lift distribution. It’s just a hunch, but I think the Oswald-factor of the Robin is considerably better than that of the 172.
Anyway, three pictures to show the washout and wing shape on the Robin (it’s our Capitaine, but the Regent has a similar wing) and on the early 172 (without distortion of the increased nose radius):
mh two very cool GA types, which is your go-to aircraft when you don’t have time to choose?
Doing what?
For land touring the Capitaine.
For instructing the 172.
For water touring the Lake.
For aerotowing the Morane.
For the pure joy of Flight the Ka2b or soon the Ka1 :-)
