Yes, reducing drag will make it go faster.
I was referring to taking an existing Vbg=95kt plane, flown at 140kt+ and loading it up internally. It won’t slow down much, and conversely won’t speed up much as fuel is burned (maybe 2kt from full to near empty tanks).
But reducing the wing size will raise Vs and SEP certification requires Vs to be 60kt or less. All IFR tourers are screwed by this figure, and are designed to only just achieve it. On some (TBM, PC12) Vs has been allowed to go to 65kt, following evidence of improved crashworthiness, and this (paperwork change of Vs) produced huge payload increases.
That’s why e.g. the homebuilt Lancairs go faster than certs for the same fuel flow. Their controllable Vs (i.e. enough rudder and aileron authority at max power at Vs, etc)is well above 60kt, notwithstanding claims to the contrary.
Peter wrote:
But reducing the wing size will raise Vs
Not if its lighter too. 
Peter wrote:
I was referring to taking an existing Vbg=95kt plane, flown at 140kt+ and loading it up internally. It won’t slow down much, and conversely won’t speed up much as fuel is burned (maybe 2kt from full to near empty tanks).
I understand, but I was thinking about the compromises and effects of retractable gear in the design phase of an aircraft. For an otherwise unchanged plane, retractable gear adds weight to reduce parasite drag in cruise. Climb performance is also reduced as a result of the extra weight. If you then increase wing area (or similar) to regain the climb rate, if must have an effect on top speed that to some degree offsets eliminating the parasite drag of the gear.
Michael wrote:
The Lancair Columbia is PROOF that a properly executed fixed gear design does not give up any significant perfomance to a RG design.
It is certainly one of the best designs around. Unfortunately we will never know what a Columbia would do if it had retracable gear.
Or actually we do. The Columbia was derived from the Lancair 4. And that is a machine which, with 350 hp will cruise at close to 300 kts.
Not certified, probably not certifyable as it is one tremendous performer which however is not trivial at all to fly.
Michael wrote:
I’ll race (and beat !) any 4 seat, normal certified production aircraft ever built.
I guess you will, unless someone comes up in an Acclaim TN.
Not if its lighter too
That’s true
For an otherwise unchanged plane, retractable gear adds weight to reduce parasite drag in cruise.
I don’t think this extra weight is significant. If you look at the components visible e.g. here, and note that there are no heavy fibreglass cowlings, I think the extra weight (the gear pump is a few kg – I have one on the bench right here) is less than a pilot eating a few too many burgers for a few months.
probably not certifyable as it is one tremendous performer which however is not trivial at all to fly.
I am sure it flies really well, but with Vs of probably 80-90kt the whole approach regime will be closer to a CJ4 than any SEP. And forget full power on a go-around below perhaps 100kt.
Peter – I think you’re missing the point: Aircraft Design is a collection of compromises.
The weight, cost (both initial & maintenance), risk (gear-up incidents) and added complexity do not justify the meager efficiency savings of retracting the gear in Light GA.
The Lancair Columbia demonstrates this admirably. Why are their no takers to my race challenge ? By the way, I will take on 6 seat retracts as well as turbos (up to 7,000’) .
Come on guys, put your plane where your mouth is !
Mooney_Driver wrote:
It is certainly one of the best designs around. Unfortunately we will never know what a Columbia would do if it had retracable gear.Or actually we do. The Columbia was derived from the Lancair 4. And that is a machine which, with 350 hp will cruise at close to 300 kts.
Not certified, probably not certifyable as it is one tremendous performer which however is not trivial at all to fly.
Michael wrote:
I’ll race (and beat !) any 4 seat, normal certified production aircraft ever built.
I guess you will, unless someone comes up in an Acclaim TN.
The Lancair IV and the Columbia 300 are significantly different, despite having the same general shape. The Columbia’s cabin is wider and the wing is completely different. That said, the NA Lancair IV with retractable gear has roughly the SAME performance as the COL3 !
The 300K you cite is for a turbo @ FL280 and reality is closer to 250K TAS which is just slightly faster than the Ttx 400 at the same FL .
As I already stated, I’ll take on an Acclaim (or any other turbo, except a Ttx 400) from SL > 8,000’
Michael wrote:
as well as turbos (up to 7,000’)
Now it gets completely silly, do that race from a 250m grass strip, and you’ll be outrun by an Ikarus C42. Of course every plane can beat every other plane if the conditions are set exactly right.
tomjnx wrote:
Of course every plane can beat every other plane if the conditions are set exactly right.
Whatever, but the topic IS about “retractable gear potentially stronger / more slippery than fixed gear (on IFR tourers)?”
Quite happy to see ANOTHER thread about short field perf …
Although I would absolutely love a race, I am not sure what that would really indicate, regarding efficiency.
But why not?
BTW, I’d bring of course a Cessna to compete with a Cessna/Columbia.
My favourite choice would be a Cessna P210; retractable, but only one door. 
As the Columbia is not a stock Cessna, I would like to use a P210 that is also not fully stock.
A Silver Eagle comes to mind.
That would be a most enjoyable day out.
complex-pilot wrote:
As the Columbia is not a stock Cessna
Why do you say that ? Mine has no mods whtasoever. Bone-stock from the factory floor, ’cept a couple of avionics changes.
I have time in the P210, have owned a T210 and own a NA210 : The NA is fastest all the way to FL100 . The P210 is a dog in terms of speed vs T210. The Columbia blows them all into the weeds.
