“Fixed gear hanging down into the slipstream (even the most aerodynamic gear fairings are still worse than doing what the birds do and tucking the gear away).”
Most of the modern studies would disagree. By the time you have added in the extra weight and the compromised wing design you break even on performance but lose out on useful load. You also have increased maintenance and insurance costs.
This one is regurgitated over and over, by fixed gear proponents or fixed gear aircraft owners.
I don't actually believe it myself. It is admittedly hard to test one way or the other, because there are so few planes which are available in an identical form but with and without fixed gear, but there are some. There is the TB10 and the TB20, fairly similar, and if you compare fuel flow rates (I don't have the data handy but remember doing it a while ago) you find that about
20-25% of engine power must be lost on the wheels. That is with wheels in generous PA28-type cowlings suitable for European-type grass airfields.
Cirrus's cowlings are more slippery than the TB10s but by compromising the tyre-cowling clearance, so you risk fouling with grass or mud, and the grass catching fire from hot brakes.
Lancair have gone nearly all the way to making the thing unusable on grass, with very tight cowlings. But their main market by far is the USA; same with Cirrus. In the USA, fixed gear is a key marketing point.
A Cirrus doesn't go any faster than a TB20, for the same fuel flow rate. Presumably the Cirrus is more slippery to start with, before they chuck it all away on the fixed gear.
For Lancair I have no data because all the fuel flow figures I have seen are for close to full bore flight, and they are understandably very high. I'd like to know what the flow rate is for 140k IAS... should be better than say a TB20 but by how much?
As to the often quoted maintenance issues: let's say you fly 150hrs/year. That will cost you about £8000/year. 20% of that is £1600/year. if you put that towards maintenance, you can have a brand new undercarriage every few years
And you will have a much better looking plane in the meantime
