Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Eugene, May 29, 2017.
I do understand the fact that bottom end of my airplane is very wide and draggy. I do understand that all this drag is positioned far below the engine and creating large moment. Large moment creating large balancing losses in the efficiency department.
Here is my question. What do we know about balancing losses for all those airplanes that fly with floats? Every time I am talking to them, they really are not complaining about anything at all. They do admit that airplane is usually 10 miles an hour slower and need a little bit more nose up trim.
Some of those floats are relatively huge, with extra weight and so many different cables to support. They must produce much more drag then my lending gear, but that doesn’t seems to bother those airplanes.
The floats are fairly streamlined but still a lot drag as you mentioned. Are those planes tractors or pushers?
It's a lot more than that. A Cessna P model with floats is more than 20 knots slower. Almost 30. 123kts down to 94.
That's why I like the LA-200. Amphibious without any performance reduction compared to aircraft with the same engines. Quite an impressive aircraft.
The balancing trim drag is relatively small. The issue is overall fuselage and engine drag.
I know local guy with LA-200 . We spend a lot of time talking about trim drag and how much slower this airplane in comparison to different airplanes with the same weight and engine power.
Yes it is different, unique, capable airplane. But from efficiency stand point it is on the very bottom of the list. He was telling me that if power is removed, nose will go straight up and you can stall this airplane in a matter of a few seconds. That should tell us that this airplane is flying around with tremendous down pressure on horizontal tail. That pressure doesn’t come for free , there is a big penalty in a form of balancing losses .
There’s a reason why insurance is very high for this machine.
Yes, this is what I hear from everybody. There is not one single problem with this airplane, but every little thing is taking away 10% .
10 times 10% = 100%!!!.
And fact that most of this problems positioned below engine doesn't help of coarse.
Someone told me that free falling drop of water have perfect shape, but only for that slow speed. As speed going up this water drop needs to get longer. Do we know how much longer? Is 60 MPH need 3:1 ratio and 100 MPH need 5:1 ?
I don't know what shape a falling rain drop has. But 3:1 ratio is about best for a streamlined body. Shouldn't matter at normal airplane speed at 60 or 100. Might matter at insect size.
The problem for your high drag aircraft is that double the power doesn't give double the speed.
The LA-200 is the fastest production amphib ever made with an O-360.
It's over 30 knots faster than the O-360 Cessna 172 amphib.
I would definitely not say it is at the bottom of the list. It's not a Mooney, but it's far faster than other floatplanes with the same engine.
So, I need to convert my Skyboy from 1:1 to 3:1 shape.
I think Rutan in his video was talking about 3.7:1 ratio. But I am not sure.
Sorry, my mistake! We were compering to regular non float planes. I will do better next time.
2.5:1 might work. Need to look up the data.
No need to apologize, it's understandable.
That ain't a bad rename, but,
I'll submit for consideration...
And if Eugene gets a boat...
Somehow Eugene strikes me as a worker not a king
Well, he works in HVAC. Might as well call it the "Skyjourneyman".
Hi PROPPASTIE ,
Regarding your observation in Post 995, I respectfully submit that I was offering up,
(in jest) a name for an airplane owned by an obviously Russian gentleman. Not at all
was I suggesting a nickname for forum member EUGENE. No doubt that he is able
to get his work done, whether in his vocation or his recreation!
Russian Airplane needs name of "Beautiful Russian Woman"
Separate names with a comma.