Wing endplates / side dams — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/wing-endplates/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
Catalog version: 2026-10-20

Sizes: see table below
- Endplates limit air spilling around the wing tips from the high-pressure side to the low-pressure side, which raises downforce and efficiency (HPA).
- UIUC tests found a larger endplate raised CL by about 0.096 at constant angle and cut drag 13.7% at constant CL (Jasinski & Selig).
- HPA's ballpark for home-built plates is to extend twice as far below the wing as above it. RC classes cap side-dam size in their rules, e.g. 40 x 20 mm on 1/10 touring cars (AARCMCC) and 80 x 80 mm on 1/10 off-road buggies (EFRA).
- Used on: Champ Car endplate (UIUC test).
- The file is a reference example built by Xem Studio from the numbers above (1/10 touring-car limits: 190 mm width, 40 mm chord, 20 mm side dam.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

parameter  value or range  source
Endplate proportion (rule of thumb)  2x as far below as above, e.g. 100 mm above, 200 mm below  HPA rear wing
Larger endplate effect  +0.0958 CL at constant alpha; -13.7% CD at constant CL  Jasinski & Selig (UIUC)
1/10 touring car side dam  max 40 mm wide x 20 mm high  AARCMCC
1/10 track car endplates  25 mm above body x 100 mm deep  AARCMCC
1/10 off-road side dam  must fit an 80 x 80 mm rectangle  EFRA
1/12 pan car side dam  max 72 mm high  EFRA

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- High Performance Academy: Aerodynamic performance devices for club level cars: rear wing theory — web — Publisher's page; dimensions are facts — https://www.hpacademy.com/courses/aerodynamics-fundamentals/aerodynamic-performance-devices-for-club-level-cars-rear-wing-theory
- University of Illinois / SAE: Experimental Study of Open-Wheel Race-Car Front Wings (Jasinski & Selig, SAE 1998) — web — Publisher's page; dimensions are facts — https://m-selig.web.engr.illinois.edu/pubs/JasinskiSelig-1998-MSEC-SAE-Trans-V107-S6.pdf
- AARCMCC: Section 3: Electric On Road, Technical Rules (Oct 2006) — web — Publisher's page; dimensions are facts — https://www.rctech.net/forum/attachments/australian-racing/180184d1162811203-aarcmcc-online-tech-road-oct-06.pdf
- EFRA: EFRA Handbook 2010, Appendix 3: Electric Cars — web — Publisher's page; dimensions are facts — https://www.efra.ws/wp-content/uploads/2010/03/Handb10App3.pdf

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/wing-endplates/index.json
API: https://xemstudio.com/api/geometry?object=wing-endplates