Pierce89 wrote:My suggestions:
1. Start your rear diffuser farther forward
2. Add a front diffuser vented behind the front wheels
3. Find a better method of attaching rear wing assembly( maybe two centered swanneck mounts and to attachments to the endplates. Also maybe move whole assembly just slightly forward so the mounting isn't so stressed and difficult to work with.
4.On the front endplate wings, are they three stacked wings or a traditional three element wing? I'd go with the latter.
5. Ignore anyone talking about drag. I'm sure you've noticed that other Unlimited cars for Pikes Peak ignore drag. If they think there's too much drag, they just add power.
6. Start working on fine geometry refinement rather than macro changes. There's a huge amount of DF in detail refinement.
I would definitely add a front diffuser.
Good points there!
1. I cannot really start it before the rear wheel axle because I do not know how big is the transmission, where is the diff, where stops the chassis, so I cannot take risks there.
2. I do not know if I got you there, but I have added diffusers underneath the front splitter. I will show pictures of this later this week. But I am interested in something I could do behind the wheels to help the flow to exit there, considering I cannot modify the chassis.
3. I would expect the wing assembly to be moved backward a bit in order to give the lower beam a better flow and help to interact more with the diffuser, but this will require CFD simulations (I have planned to do that).
4. They are 3 stacked wings, and I found them to be quite unproductive, especially the 2 upper profiles which could be predicted. I will indeed try with a single element or with a typical assembly (as you mentioned).
5. This is correct, however, I have a L/D ratio objective of -1.5:1 which I see no problem to obtain.
6. Again, I agree there, but before refinement, I have to seek for the best wing position/AoA for example, or diffuser geometry, devices to be added/removed/modified. I will probably won't be able to do small adjustments in the time scale that I have, so I try to focus on trying devices (gurney flaps, vortex generators, small wings, etc.) rather than changing angle of wings by 0.1°. But you are right in saying detail makes a big difference. Its just that I have first to find a kind of "optimum" with the large modifications.