Airspeed at sea level

I got interesting airspeed calculator Excel-sheet from Petri Flander. I have been calculating those things with my aircraft design program and by hand before, but it is surprisingly handy to see the effect of various flat plate drag areas and their effect to the airspeed. Great input for my program which I am writing the UI for with Qt right now, I may do also graphical output for these parameters, would be fun to have. This was actually also useful to reverse-engineer the flat plate drag areas of various aircrafts. For example I came up with 4,7 ft2 for Cirrus SR20 where Lancair ES (=same as Columbia 400) is 4,0, so Cirrus is a slightly less efficient than the Columbia (which is evident also from the performance numbers comparing SR22 and Columbia 400). Interesting is that I came up with 9 for C152, which is a terribly bad figure. And Zenair CH701 produced a number around 18 which was reverse-engineered from real performance numbers I have heard from a Zenair pilot. Couldn't get much worse than that. BD-5 has very low figure of 0,9 and Vmax probe is at 0,3 (these were obtained from elsewhere). A composite BD-5 with rear body laminar flow suction (with more laminar body shape as well) and some high tech airfoil like the NLF414F could be super-efficient. However, the issues with low Reynolds number from Vmax probe apply, it will have seriously dangerous stall charasteristics without modifications to the airfoil or wing.

Here is a copy paste from the sheet with flat plate drag areas from 0.3 (Vmax probe) to 4 (Lancair ES):

        Aircraft speed, km/h                    Prop eff        0,85    Dens.ratio      1,000       $

Drag area            
ft2     25      40      60      80      85      90      100    <- Total hp  (Rotax 914)
4       148     173     198     218     223     227     235     127,053 kts
3,00    163     191     218     240     245     250     259     139,840 kts
2,40    176     205     235     259     264     269     279     150,639037908943        kts
2,30    178     208     238     262     268     273     283     152,791314948939        kts
2,20    181     211     242     266     272     277     287     155,07211859505 kts
2,12    183     214     245     270     275     280     290     156,998677308782        kts
2,10    184     215     246     270     276     281     291     157,495511877874        kts
2,00    187     218     250     275     281     286     296     160,077864487362        kts
1,90    190     222     254     280     285     291     301     162,838370152973        kts
1,80    193     226     259     285     291     296     307     165,799714672936        kts
1,70    197     230     264     290     296     302     313     168,988949701208        kts
1,60    201     235     269     296     302     308     319     172,438652178898        kts
1,50    205     240     275     303     309     315     326     176,188487565227        kts
1,40    210     246     281     310     316     322     334     180,28735558483 kts
1,30    215     252     288     317     324     330     342     184,796395706893        kts
1,20    221     259     296     326     333     339     351     189,793294797389        kts
1,10    228     266     305     336     342     349     361     195,378626469698        kts
1,00    235     275     315     346     353     360     373     201,685471089846        kts
0,90    243     285     326     359     366     373     386     208,894550582996        kts
0,88    245     287     328     361     369     376     389     210,46524527855 kts
0,50    296     346     396     436     445     454     470     254,107770484061        kts
0,31    347     406     465     512     522     532     551     298,003054739616        kts