The numbers there don't make sense. Unless the defiant is a brick.
... Of course those numbers don't make sense.
... Same as comparing apples to oranges don't make sense either.
... There are some similarities between those planes (like between apple and orange), but there are more differences.
... First, Defiant is fixed gear airplane, Velocity retract gear
... if someone thinks it really doesn't matter, take a look at Waiter LongEze.
... with retract gears, at low altitude he gained 10kts, however at higher difference is marginal.
"At FL180, I only seen a 2 kt improvement, but lost about 5 gallons of fuel and about 100 lbs of useful load." Plus the cost of the Retracts.
Flying at Sea Level is difficult for me, as the water keeps getting in my way.
75% power is 75% power. Both planes should be using about the same amount of fuel. They aren't.Of course those numbers don't make sense. Same as comparing apples to oranges don't make sense either. There are some similarities between those planes (like between apple and orange), but there are more differences.
Seems that you guys took this apples vs oranges part too seriously. Just to finish it, last sentence in relation to it. There are some similarities between apples and oranges, but there are also differences, I see probably more differences between those two airframes (retract vs fixed, etc) than you guys, but that might vary.As for apples to apples. Both planes are, canard designs, twin engine, with the same engine, with the same number of passengers. That's pretty apples to apples.
75% power is 75% power. Both planes should be using about the same amount of fuel. They aren't.
What else doesn't make sense, is the plane with the greater frontal area, and higher weight, is climbing faster on one engine. That... doesn't make a whole lot of sense to me. I'm not saying it's impossible just unlikely.
Four posts up, or something like that. Here's the link: http://www.homebuiltairplanes.com/f...its-twin-canard-development-2.html#post155077First I don't know where are those numbers from,
See, that makes a lot more sense. I wasn't favoring either airplane in my "this makes no sense" post. I was calling the numbers into question.I've seen different ones, for example single-engine climb rate for Defiant 390 feet/min not 310. Cruise for Velocity V-twin 170 kts, not 185 kts, etc. Which numbers are the real one, I don't know. So for this reason entire discussion is a little bit pointless in my opinion, I just think that Defiant push-pull configuration might be a better idea, for twin canard.
My use of the word "brick" was a joke, I was trying to point out that the numbers seemed very wrong to me. Neither airplane is an aerodynamic mess. The reason I stated the velocity has a greater frontal area (and I can check it... but I'm pretty sure i'm on the money here) is the rutan doesn't give passengers any extra space, and the defiant has no engine nacelles to deal with on the wings.On the other hand, from those two Defiant is closer to a brick. I don't know what is your sentence "the plane with greater frontal area" based on. What's really count is the equivalent of flat plate area http://www.homebuiltairplanes.com/f...uivalent-flat-plate-areas-various-planes.html
I believe it's much larger for Defiant (fixed gears, brick a like shape, terrible rear cowling, etc)
It's probably best not to try to point at any one issue with the starship. The list of what was wrong with the plane is longer than what they got right. The engine pods and fuselsage made a divergant duct, causing flow separation at all speeds. It's not unlike carrying a parachute in there. The plane was massively overweight, and that alone would have slowed the plane down.Anytime you put the prop in the back, it is in the sinusoidally varying downwash of the wing, which automatically makes the prop efficiency go down. That was why the Beech Starship was not as good a performer as it should have been. There was a bunch of work done with propellers to get it to contract speed in the first place.
I had forgotten about the fixed pitch props.Burt came up with the Defiant as a poor man's twin and a pretty safe one at that. Originally it had fixed props, which made engine out procedures bone-head easy.
Israel (dead sea), US (Death valley), the Cradle of mankind (something depression, Ethiopia) etcbecause nobody beside people in Holland flies so low.
A big advantage is that the running engine blows the fin straight, much like in the Cri-Cri, such that you need less rudder than with a conventional twin.So, put two aft, and you get lousy efficiency on both. They give you asymmetric thrust in an engine out case, so you are almost in the same boat as a conventional twin for emergency procedures. And with the very short vertical tail arm, I wonder if it has enough yaw damping.
A big advantage is that the running engine blows the fin straight, much like in the Cri-Cri, such that you need less rudder than with a conventional twin.
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