Unanswered Questions
24 questions with no upvoted or accepted answers
2
votes
1
answer
361
views
Can I reduce drag with channeling freestream air at the backward facing surface?
Idea is to increase static pressure at backward facing surface to reduce drag.
Can I reduce drag with channeling freestream air at the backward facing surface, like picture suggest?
CommunityBot
- 1
2
votes
0
answers
122
views
Is skin friction also pressure drag looking at microscopic level?
Roughness in boudary layer is taller than height of air which is not moving ,feel oncoming airflow in boudary layer, at front side must be high pressure at rear low pressure etc,so net force is to the ...
CommunityBot
- 1
2
votes
0
answers
114
views
Why is hybrid laminar flow control preferred for swept wings over other options?
As I understand it, a (the?) major form of laminar-to-turbulent transition on the swept wings of large jets is the crossflow caused by the sweep. One way to control this is laminar flow control by ...
- 3,989
2
votes
1
answer
275
views
Why is it harder to maintain laminar flow on larger aircraft?
I am told that on larger aircraft, suction will be needed to maintain laminar flow because of the larger leading edge radius. Why so? Is it because the air has to travel over a longer distance on the ...
- 23.1k
1
vote
0
answers
94
views
how does a Sear Haack body and rotation interact
If a Sear Haack body is launched out at supersonic speeds and given a extremely high rotational speed will the Sear Haack body stay stable over a long distance or will it start to tumble and if it ...
- 11
1
vote
0
answers
136
views
Looking for a way to search through airfoils based on Cl/Cd at a specific angle of attack
I'm working on a university project to design a wing that has a high Cl/Cd value when placed in a wind tunnel at an angle of attack of 6 degrees and a windspeed of 25m/s.
So far I've been using ...
- 103
1
vote
0
answers
111
views
2D vs 3D Pressure Drag
What is the difference between the parallel component of the drag that depends on alpha for a 2D airfoil and the parallel component of the drag that's on a finite wing?
I understand that for a wing ...
1
vote
0
answers
63
views
How much of the Virgin GlobalFlyer's L/D is due to laminar flow?
Despite travelling much faster than the Voyager, it has a significantly higher L/D. The latter seems to have two features that disrupt laminate flow, that are absent in the former. Namely the canards ...
- 3,989
1
vote
0
answers
107
views
What type of probe can measure induced drag in the wake?
Induced drag can be measured from velocity preturbation in Treffz plane.
In Treffz plane what velocity direction is important for induced drag, vertically down, lateral(horizontal, "spanwise&...
- 2,290
1
vote
0
answers
107
views
Determining optimum area of parafoil, and then drag
I am designing a parafoil recovery system for a small payload of 300x100x500mm (2.4kg).
I have chosen an Aspect Ratio of 3, and from a NASA wind tunnel test report, the coefficient of lift and drag is ...
1
vote
0
answers
98
views
Is there a formula for calculating drag coefficient based on the 4 digit NACA airfoil?
Are there any existing formulas that can be used, or maybe some methods to derive an equation that can calculate the drag coefficient based on the NACA airfoil?
- 31
1
vote
0
answers
294
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Drag estimation of Xfoil and Vortex Lattice Method?
I have been working on building a software to estimate lift and drag properties of a fixed wing being tested at a wind tunnel. The setup is a low AR wing with NACA0012 profile and 0.3m chord, with 0.4 ...
- 11
1
vote
0
answers
143
views
How much is thickness of air layer with zero velocity at wing surface?
How thick is the layer of air that is not moving(zero velocity) at the surface of wing, and can this be taller than the relative roughness height?
Because everything that is inside this layer (V=0) ...
- 13
1
vote
0
answers
92
views
Is it true that blowing cannot be used for laminar flow control? Why?
Aerospace Engineering Desk Reference, page 505
Tangential blowing can only be applied to the prevention of separation...The flow caused by blowing tends to be very vulnerable to laminarturbulent ...
- 3,989
1
vote
0
answers
610
views
what is the physical explanation for additive drag?
from what i understand, additive drag is not really drag. it is a way to account for the variation of inlet condition due to conservation of mass.
but i still don't get why it create drag(negative ...
- 411