Does size matter.

[mxman70]

After extensive research i 've decided to build a Rutan ship. Cozy mk4 or Defiant. Had a curious(and possibly irrelevant) question. After looking at many designs, both certified and experimental, I came about the question of fuselage size. As a example I use the Beech Baron. One four seater and one six. Same wingspan. Same wing area. Longer fuselage to accomidate extra seats.Was the four seat wing overbuilt or are they pushing the limit with the six seater? I understand it's the reverse of a canard but curious. Not that I plane on making a 737 out of a defiant mind you. Just curios. Thanks, Patrick

[Marc Zeitlin]

... I came about the question of fuselage size. As a example I use the Beech Baron. One four seater and one six. Same wingspan. Same wing area. Longer fuselage to accomidate extra seats.Was the four seat wing overbuilt or are they pushing the limit with the six seater?

First of all, if you're talking about comparing a COZY MKIV to a Beech Baron, your statements about wingspan and area are incorrect. The COZY MKIV has 100 sq-ft of wing area and a span (not that it matters) of 29.5 ft., while the Baron has a wingspan of about 37 ft. and a wing area of 199 sq-ft. - twice as much (not surprising, as it's MGW is over twice that of even the heaviest COZY MKIV out there).

 

So, what planes are you trying to compare, and what, exactly, are you trying to figure out? It's not at all clear from your question(s).

 

With respect to structural integrity (if those are the "limits" you're asking about) wing area and wingspan are not measures of the structural strength of anything - they're aerodynamic parameters, not structural ones. All certificated aircraft must meet certain structural requirements - the Baron is either a Normal or Utility category aircraft, in which case it must be able to withstand 3.8 or 4.4 G's respectively at MGW.

 

The COZY MKIV is not certificated, and can have whatever specifications the designer chooses - in the case of the COZY MKIV, Nat Puffer states that it's the equivalent of a Normal category aircraft, and should be flown as if it's been designed for the 3.8 G limit (with a MGW of 2050 lb). Those folks flying at higher MGW's SHOULD be reducing their G limit commensurately (but probably aren't, since most of them don't understand these issues).

[WolfManSpecial]

Mr ZEITLIN:you are more clear than water,thank you

[mxman70]

Thank yoMark. I kind of figured you would have a answer. To be specific. The comparison I was trying to make was the two barons with the different seating capacities. 4 vs. 6, with the same wing area.

[TMann]

Thank yoMark. I kind of figured you would have a answer. To be specific. The comparison I was trying to make was the two barons with the different seating capacities. 4 vs. 6, with the same wing area.

....... somewhat like comparing the Cozy (4 place) to a Long-Ez (2 place)

(In terms of wing loading)

[Marc Zeitlin]

... The comparison I was trying to make was the two barons with the different seating capacities. 4 vs. 6, with the same wing area.

The number of seats is immaterial - the question is, what's the MGW of each aircraft? Structurally, if the MGW is increased, maybe they beefed up the spar - wouldn't see that from the outside. Maybe the MGW is determined by landing gear strength - who knows what the design limitations were based on?

 

From an aerodynamic standpoint, unless the airfoil or flap system was modified, you can expect a higher MGW aircraft to have a higher stall speed than the lower MGW aircraft. If the stall speed is still within the FAR requirements, then it's OK to raise the MGW while leaving the wing size alone.

[mxman70]

OK. Thanks. That's what I was looking for.

[DemonFrog]

i think if you go above 5 seats you also need a second door. like the apache/azted bros. the apaches were 5 seats and the aztec had to have another door to go to 6. yes the aztec had a whole lot more power, but i'm just giving an example of other possible reasons.

[mxman70]

The curiosity isn't totally irrelevant I guess. Big motor in back and or fat guy in front.Although 120 kt. stall would probably be undesireable. That and lack of catapults at most airports.....

[Rydogg]

The curiosity isn't totally irrelevant I guess. Big motor in back and or fat guy in front.Although 120 kt. stall would probably be undesireable. That and lack of catapults at most airports.....

LOL, catapults would be awesome!

[Drew Swenson]

I have a couple of cats here at work----as well as a couple of scaled prototype electric cats---and in the process of laying down a full scale electric cat. First electric cat going into the USS Ford. Oh---I have some jet car tracks too---asked to see if I could mount seats on it---they thought I was crazy---maybe so.