1 / 11

Wall Correction Issues Jeff Gerhart July 15 th , 2010

Wall Correction Issues Jeff Gerhart July 15 th , 2010. Corrections at UWAL. Delta CD_ANG =. Online vs. Final Data. Online data is found using the Online.exe program real-time during testing. Since it is done real-time, the corrections applied are not completely accurate.

telyn
Télécharger la présentation

Wall Correction Issues Jeff Gerhart July 15 th , 2010

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wall Correction Issues Jeff Gerhart July 15th, 2010

  2. Corrections at UWAL Delta CD_ANG =

  3. Online vs. Final Data • Online data is found using the Online.exe program real-time during testing. Since it is done real-time, the corrections applied are not completely accurate. • In the Online.exe program wall corrections are found using the same equations as the Force.exe program uses to find Final data. The main difference in the wall corrections is how each program finds CLW (Lift of just the wing). • Online: Online is not given a “tail-off” run in order to find CLW, so it has to use what it is given, so it assumes that the lift from the tail is negligible compared to the wing, and says CLW = LB/(Qa*Sw), where LB = measured lift after balance interactions, but no tares or other corrections. So this is not the true wing-only lift of the configuration. • Force: Since Final data is calculated after the test is completed, or at least later in the testing, tail-off runs for each configuration can be found and applied to the runs. For the Final data CLW = (LB_tail-off config)/(Qa*Sw). This is the correct way to apply wall corrections according to our methods.

  4. Online vs. Force Final (Force) Data, similar corrections vs alpha b/c corrections based on actual lift set Online Data, similar corrections vs CL b/c corrections are based on the CL of the config, not the lift set

  5. Online vs. Force • Similar issue between Online and Final (Force) data for delta CD_WC, delta CM_WC, delta Alpha_WC because CLW is in each of their equations.

  6. Bump in Delta CM_WC • The bump seen in dCM_WC seen around alpha = 22-24 degrees is caused by the CMS set used. CMS sets are the DCM/DDS for the model. Where DS is the stabilizer angle. The CMS set used for this test was found using a different tail then the tail installed in runs 155-169. We used tail H1.6F to make the CMS set.

  7. Bump in Delta CM_WC • The equation for DCM_WC: DCM_WC = -57.3(deg/rad)*DELAS*DCM/DDS*CLW*(Sw/C) Rearranging the variables: DCM_WC = (-57.3*DCMDDS) * (CLW*Sw/C) * DELAS

  8. Bump in Delta CM_WC DCMDDS gives bump This down slope in DCMDDS explains why DCM_WC flattens out at AoA~16-20 Similar Trend to DCM_WC CLW gives overall shape

  9. Bump in Delta CM_WC When scaled to similar magnitudes, the trends between Delta_CM_WC and DCMDDS are evident

  10. Bump in Delta CM_WC • After Alpha = 30 the DCMDDS is constant. This is because the CMS Set only goes up to Alpha 30. The data reduction programs do not extrapolate, so they hold the last value and apply it to higher AoAs. • The bump in the CMS Set is explained by the stall that occurs at that angle of attack and the bump is seen in the CM-Alpha Plot. This bump in CM-Alpha was semi-independent of which tail was installed, it would only change in magnitude.

  11. Bump in Delta CM_WC Bump in CM at AoA ~ 22-26

More Related