Quote from: Robotbeat on 08/07/2016 05:56 pmQuote from: AncientU on 08/07/2016 05:50 pmQuote from: Robotbeat on 08/07/2016 05:24 pm2020 and exomars aren't going to be significantly larger than MSL.This is a dumb way to argue. Please bring better game.Fine. What evidence is there that MCT will use a HIAD?There's some indirect evidence that it may be one of several options they'll consider.I don't disagree that it will be or already was considered; there are many possibilities that will be discarded as not optimum or unworkable.Certainly no evidence that it will be used on Red Dragon, which would be the obvious opportunity to test it...
Quote from: AncientU on 08/07/2016 05:50 pmQuote from: Robotbeat on 08/07/2016 05:24 pm2020 and exomars aren't going to be significantly larger than MSL.This is a dumb way to argue. Please bring better game.Fine. What evidence is there that MCT will use a HIAD?There's some indirect evidence that it may be one of several options they'll consider.
Quote from: Robotbeat on 08/07/2016 05:24 pm2020 and exomars aren't going to be significantly larger than MSL.This is a dumb way to argue. Please bring better game.Fine. What evidence is there that MCT will use a HIAD?
2020 and exomars aren't going to be significantly larger than MSL.This is a dumb way to argue. Please bring better game.
I think there's a reasonable chance no such device will be used for MCT, for the sole reason that reusable controlled reliable powered landing is neither fully compatible nor fully benefitted by HIAD;
Quote from: Burninate on 08/07/2016 10:40 pmI think there's a reasonable chance no such device will be used for MCT, for the sole reason that reusable controlled reliable powered landing is neither fully compatible nor fully benefitted by HIAD;I thought HIAD was a technology for relatively small scale EDL (NASA@Mars)? Here we are talking about ships that are as large as projected HIAD brake area, so why waste mass?
HIAD is scalable to enormous sizes. It's not just for small scale EDL.
Quote from: Robotbeat on 08/08/2016 12:34 amHIAD is scalable to enormous sizes. It's not just for small scale EDL.Developed by NASA in that way? I only see them developing HIAD as a stage before using parachutes and parachutes limiting the downmass to Mars severely. Combining HIAD with SRP seems a serious headache.
Yes, I am fully aware of that. But how much more than the 1t limit they have reached with Curiosity? No word on that in there. Will it support manned ERV MAV?
It's nearly certain that some sort of deployable drag enhancement device will be used for MCT.
Quote from: Robotbeat on 08/07/2016 08:26 pmIt's nearly certain that some sort of deployable drag enhancement device will be used for MCT.IMO deployables will be limited to control surfaces much smaller than the heatshield. I tend to doubt that they will use inflatables, just because it's unnecessary complexity if they are willing to spend 1 km/s of delta-v on EDL.
Quote from: Torbjorn Larsson, OM on 08/07/2016 10:59 pmQuote from: Burninate on 08/07/2016 10:40 pmI think there's a reasonable chance no such device will be used for MCT, for the sole reason that reusable controlled reliable powered landing is neither fully compatible nor fully benefitted by HIAD;I thought HIAD was a technology for relatively small scale EDL (NASA@Mars)? Here we are talking about ships that are as large as projected HIAD brake area, so why waste mass?HIAD is scalable to enormous sizes. It's not just for small scale EDL.
Quote from: envy887 on 08/08/2016 12:46 pmQuote from: Robotbeat on 08/07/2016 08:26 pmIt's nearly certain that some sort of deployable drag enhancement device will be used for MCT.IMO deployables will be limited to control surfaces much smaller than the heatshield. I tend to doubt that they will use inflatables, just because it's unnecessary complexity if they are willing to spend 1 km/s of delta-v on EDL.The trade is that to reduce the maximum g forces, you need to increase the available negative lift. If you have more negative lift, you can decelerate more gradually, higher in the Martian atmosphere. It will be interesting to see what SpaceX deem the maximum acceptable g forces. I suspect that will determine the size of any enhancements.
....I would guess retrorockets is the far easier, cheaper method to scale tough.
How far can NASA's current HIAD scale?
........Yes, I can't see a company invest in added mass and (fragile) complexity unless it is really necessary. By the way, wouldn't the side of a large craft offer a lot of negative lift? [Not an aerodynamist ... obviously.]
A very thorough presentation of ideas for BFR/MCT from "coborop" at Reddit:https://www.reddit.com/r/spacex/comments/4wks2h/fanmade_mct_and_bfr_architecture_cad_and_math/Beautiful renders!:https://imgur.com/a/2k10I