From memory, it has been said that the first launch will be at 82% thrust.
Quote from: speedevil on 01/01/2018 02:11 pmFrom memory, it has been said that the first launch will be at 82% thrust.And from actuality (not your memory), it will fly at 92% thrust. Not 82%. And not just "has been said," but tweeted by Elon Musk.It's refreshing to see other people have even worse memories than I do...
If the engine failure at the side booster happens before the throttle back of the center core, the situation may become hairy as the thrust difference between center and side boosters might not work with the structure of the heavy assembly. Maybe the center would have to throttle back prematurely.The thrust to weight at launch should be around 1.5. With 11% thrust missing it should still be launching without much problems.
Quote from: Semmel on 01/01/2018 04:32 pmIf the engine failure at the side booster happens before the throttle back of the center core, the situation may become hairy as the thrust difference between center and side boosters might not work with the structure of the heavy assembly. Maybe the center would have to throttle back prematurely.The thrust to weight at launch should be around 1.5. With 11% thrust missing it should still be launching without much problems.One engine is 3.7%
Quote from: AncientU on 01/01/2018 05:08 pmQuote from: Semmel on 01/01/2018 04:32 pmIf the engine failure at the side booster happens before the throttle back of the center core, the situation may become hairy as the thrust difference between center and side boosters might not work with the structure of the heavy assembly. Maybe the center would have to throttle back prematurely.The thrust to weight at launch should be around 1.5. With 11% thrust missing it should still be launching without much problems.One engine is 3.7%If center and opposite core need to match the loss of thrust, it's 11.
I think this is an interesting conversation. However I believe it would be better suited to be on the general Falcon Heavy discussion thread rather than on this mission specific thread?
The 92% thrust level might only be for this mission.
Quote from: Nomadd on 01/01/2018 09:25 pm The 92% thrust level might only be for this mission.I've wondered if the thrust "reduction" on this mission is just because he's giving thrust numbers for FH Block 5 and this vehicle is running at Block 3 levels.
It's safe to say that this will be only Falcon Heavy ever to use pre-Block 5 cores. After re-scoping Falcon Heavy to chase F9 iterations to v1.1 and then to FT specifications, now there's Block 5 coming. SpaceX needed to make the decision whether to bring the FH demo vehicle up to Block 5 spec with bolted octowebs etc. and accept further delays to a program already repeatedly delayed by F9 iteration churn -- or to simply launch the damn thing already even though it will end up being a one-off. This will forever be the unique "albino" FH demo vehicle.
First time poster.Regarding the 92% thrust.Is this not simply because it's an LV capable of lifting 16000kg to MTO that is in fact only lifting off with a 1500kg payload. An LV that can hoist 60000kg off the pad only lifting 1500kg (or whatever the weight of the tesla + mounting is) would go into a massive over g situation within seconds lifting that light a load. As it is I would imagine the 92% will only be until it clears the pad, then a massive throttle down until well past max q and throttling down all the way up. A lot of rockets auto throttle to constant 5g acceleration for structural reasons IIRC. This baby in its maiden config will have plenty of horses to spare.Or am I wrong on that?Edit: Does anyone know if there is extra ballast in the payload to counteract this? Or what the actual final payload weight actually will be?
there is abou 135000 lbs difference between max payload and that tesla I believe the shuttle and falcon max q points are similar(13-14km).at max q i'd expect the boosters in the FH configuration to have burned over half their fuel, with the core down by a third of it's fuel, at which point that 135k lbs in the nose becomes a much greater ratio of the remaining weight of the craft, which in turn adversely affects TWR forcing more throttling etc.I thought throttling was used to maintain a specific TWR so as not to accelerate too early in the flight where the atmosphere is thicker where overspeed can lead to instability, extra structural loading and heating from excess aerodynamic resistance etc. I would imagine that the core booster will throttle down earlier to offset the light payload.anyway. just my basic understanding of rocketry
there is abou 135000 lbs difference between max payload and that tesla