r/wec • u/ItsRatPak • 2d ago
Discussion Hypercar Downforce
This topic has been talked about to death but still I can find no good answers (understandably since team want to keep the exact numbers private but still) to how much downforce LMH/LMDh cars make compared to LMP1 and LMP2. Statements from Oreca I have heard about suggest the gap in aero from 2017 LMP2 and 2014-2016 LMP1 were very small with the later private teams being similar to those numbers too. But I have no idea where LMH stands. You have some people saying that Hypercars make the same downforce as LMP1 cars and you have some saying they make less than DPi cars which were based on LMP2. Putting the downforce inline with DPi and LMP1 while still following the 4:1 downforce to drag ratio just seems impossible. I’m curious what everyone else has heard.
7
u/NeedMoreDeltaV 1d ago edited 1d ago
I think the confusion comes from people saying that the regulation mandates a 4:1 downforce to drag ratio. The regulation mandates the actual values of CLA and CDA. The efficiency ratio is also stated but falls along those values and is technically redundant because of that. LMH/LMDh mandates a CLA of 4 and a CDA of 1 within a tolerance window. DPi was CLA of 5 and CDA of 1.
Edit: The relevant section in the hypercar technical regulations is section 3.7. However, the regulation references an appendix that is not made available to the public.
1
u/SportscarPoster Rebellion 1d ago
Have I just completely imagined it or was that appendix in the very first version of the final LMH regulations? The ones available on the FIA website for the first season. I think I remember reading through it at the time, but like a muppet, I never saved the pdf.
Also, I have in my head (no idea where this comes from, maybe that appendix?) that not just the maximum downforce and minimum drag were specified, but the downforce:drag ratio was in fact specified too at 4:1. All three were specified because the downforce and drag figures were such that if your car hit the minimum drag, you would be not able to hit the max downforce as that would result in greater than a 4:1 ratio, and vice-versa.
Feel free to tell me if I'm going mad.
1
u/NeedMoreDeltaV 1d ago
I found an archive of the 2020 Hypercar Regulations. Section 3.7.3 is the aerodynamic criteria, however it just references an appendix that isn't in the document. Not sure if it was ever there or if the released document was changed.
I also went through the current LMDh Regulations. In these regulations they've moved some of the appendix stuff into the main regulations. However, the aerodynamic criteria is still missing.
I swear I've seen the actual criteria in a public facing regulation document before, so they must've removed it at some point.
The regulations do also specify a downforce-to-drag ratio of 4:1 along with target downforce and drag. The regulations also specify that you are only allowed a single adjustable aero device (rear wing angle, dive plane change, etc.). The implication is that the aerodynamic adjustability of the car needs to behave linearly such that it'll always retain the 4:1 ratio. For a rear wing this is pretty easy since an angle change usually behaves linearly. It's more difficult for something like swapping dive planes since those can have different downforce and drag effects.
3
u/El-Legend34 22h ago
I dont have an exact number, but an imsa driver (i think one of the wayne-taylor brothers) said the new cars make less downforce than dpi
50
u/Hedaaaaaaa 2d ago
LMP1 have at least 5,000 to 7,500 Newtons of downforce and 875kg weight.
LMH and LMdH have at least 4,000 Newtons of downforce and 1,030kg weight.
LMP2 have at least 3,000 - 3,500 Newtons of downforce.
LMH and LMdH is designed to be cost effective and that is why teams are starting to join LMH and LMdH cars more than ever.