Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Eugene, May 29, 2017.
I think the engine above the wing (like that and Seamax) is less drag.
SALUTE TO EUGENE'S RUSSIAN Experimental Thinking!!!
Russian Philosophy On Fighter Jets -
TOUGH, MANEUVERABLE, PRACTICAL!!!
Certainly Worth Factoring Into Anyone's Thinking !!!
I was thinking about making nose sharper, but they tell me that this would be waste of time.
Sharper won't help.
Looking at that first photo (front view) the armpit area of the gear legs looks like a choke point for airflow.
Angles less than 90° are not good. That's not a normal design feature and unique to that design.
Could fill those armpits maybe to make it 90° to the fuselage. It is faired some but maybe not enough.
Here is another stupid question -
- in level flight we are moving draggy object through the air. Drag of this object have center. We should try to install our engine inline with this center. If we don't = we will have moment arm = balancing drag.
So, moment arm has nothing to do with CG, when we are talking about drag? Were CG is located vertical is irrelevant.
Its what I would call center of drag but since almost everything is below the thrust line then yes, there is a moment to consider. I said CG because most people understand that term better. When I design RC planes this is always something I consider.
If you had a small turbine mounted behind the cockpit pushing through the center of drag/mass then this thread wouldn't exist. Well, maybe for the turbulence/stability issues
Yes, CG has no effect on the moment arm of drag. They just use similar calculations, turned 90 degrees from one another. But are completely unrelated otherwise.
From Peter Garrison -
"3. The flow over the aft portion of the fuselage is separated. This has the effect of immersing the stabilizer in a turbulent wake and reduces its effectiveness.
The model I created does not include the boom, landing gear, vertical fin, or engine, whose effects on lift and pitching moment are small."
So, nothing is black and white in aircraft design like I was thinking 3 years ago. Some very smart people still disagree on simple fundamentals. Like landing gear has small effect on pitching moment.
Thats why I suggested VGs earlier as it would allow for better flow.
Yes, but you may create a different trim condition so you may need to abort if it feels weird. Just a heads up.
One row of vgs will not help much. The whole back section should look like a windmill farm. VGs don’t stop the swirling as much as they suck it in , making the dead spot smaller. Or you could have little wings like German Touring Car Racing
I was thinking the same thing. The Schweizer 300 has a wing on top of the cabin for the not too elegant shape.
My designer doesn't like vortex generators at all. Sure there is time and place for them. In his mind they always producing more drag than doing good. VGs can be used as temporary band-aide. If you need to use them = you made some kind of mistake. Correctly designed aircraft normally should not need them at all.
I think by now we all agree that rear cowling on Skyboy was probably ok for 65 mph Quicksilver competitor with enclosed cabin. But for 100 mph aircraft I need to shape it differently.
What I am trying to say, is that most likely rear cowling eventually will be completely or partially rebuild in to different shape in the future. So why couldn't I drill some holes to find out pressure drop. I really like that Idea. I can also build up using foam different shapes and test fly to find out pressure drop changes.
Worst that can happened, that I will to fly to Oshkosh this year with 100 little holes in my airplane. So what! I can cut round 1" pieces of white tape to cover all holes. It will look cool! Nobody will ever know what is it. There is white tape on my airplane already everywhere you look!
Eugene, you are the definition of experimental aviation. We are all living vicariously through you. But you don't need that many holes!
Can one of this bolts be used as test ports? I think test tube will go right over the threads on the inside.
They are button head so will give a higher reading if there is good flow over the surface because they will expand the air over the head. If the flow is stagnant then its good. But you don't know that yet.
A hole that the tube itself can be squeezed into would work. It shouldn't protrude higher than the surface.
Static ports that have proven to be accurate on several airplanes are made with a hole in the center of a disc about 1 1/2” in diameter that is raised about 1/8” above the fuselage surface.
Got it! Thank you! I will think about something, without spending $1000.
Yeah, just like the ones I put on the Max. Thats why they are 1.5" diameter so the flow is straight across the hole. Well, as straight as can be on a small disk.
If we make the air do work by flowing around a curve then it changes the air pressure. The button heads will do that. That was for general info since I know you know that.
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