https://twitter.com/jeff_foust/status/1067432050431451140https://twitter.com/jeff_foust/status/1067433130460467202
This thread prompted me to look at their website again and found this:https://fireflyspace.com/launch-gamma/Looks like it shoots the second stage out the rear end and they are talking about cross feed. Pretty crazy stuff.
Quote from: ncb1397 on 11/27/2018 06:48 pmThis thread prompted me to look at their website again and found this:https://fireflyspace.com/launch-gamma/Looks like it shoots the second stage out the rear end and they are talking about cross feed. Pretty crazy stuff.Yikes. Someone at Firefly really likes wings. I mean REALLY LIKES wings. Those wings and control surfaces are huge beyond practicality.
Quote from: Lars-J on 11/27/2018 10:05 pmQuote from: ncb1397 on 11/27/2018 06:48 pmThis thread prompted me to look at their website again and found this:https://fireflyspace.com/launch-gamma/Looks like it shoots the second stage out the rear end and they are talking about cross feed. Pretty crazy stuff.Yikes. Someone at Firefly really likes wings. I mean REALLY LIKES wings. Those wings and control surfaces are huge beyond practicality.If I'm reading that page right, Gamma is using the same 62 in. payload adapter as the Alpha and Beta. So this thing isn't exactly huge. Just eyeballing it, I'd say it's about the same size as VG's SpaceShipTwo.
Quote from: whitelancer64 on 11/27/2018 10:25 pmQuote from: Lars-J on 11/27/2018 10:05 pmQuote from: ncb1397 on 11/27/2018 06:48 pmThis thread prompted me to look at their website again and found this:https://fireflyspace.com/launch-gamma/Looks like it shoots the second stage out the rear end and they are talking about cross feed. Pretty crazy stuff.Yikes. Someone at Firefly really likes wings. I mean REALLY LIKES wings. Those wings and control surfaces are huge beyond practicality.If I'm reading that page right, Gamma is using the same 62 in. payload adapter as the Alpha and Beta. So this thing isn't exactly huge. Just eyeballing it, I'd say it's about the same size as VG's SpaceShipTwo.It's not the size that worries me (it is unknown), it is the proportions of propellant tanks to airframe. This is thing will have a very bad dry mass ratio.It also seems to be under the mistaken assumption (IMO) that a launch vehicle needs to spend as much time in the atmosphere at hypersonic speeds as possible. This looks more like a proposal made to make the DoD interested in it as a hypersonic bomber, not as a practical launch vehicle.
It also seems to be under the mistaken assumption (IMO) that a launch vehicle needs to spend as much time in the atmosphere at hypersonic speeds as possible.
It's not the size that worries me (it is unknown), it is the proportions of propellant tanks to airframe. This is thing will have a very bad dry mass ratio.
Quote from: Lars-J on 11/27/2018 11:10 pmIt's not the size that worries me (it is unknown), it is the proportions of propellant tanks to airframe. This is thing will have a very bad dry mass ratio.Does a high dry mass ratio on the 1st stage really matter that much though? It isn't an SSTO. If you are having problems wrapping your head around the concept, just consider it air launch but the airplane is rocket powered, not air breathing, and flies much faster than a normal sub-sonic air launch scenario that would normally require 2 stages+ after that.
It looks like a SSTO but they say 75% reusable, with a 1st and 2nd stage. Do the internal 1st stage side tanks and engines get dropped some how?
Quote from: ncb1397 on 11/27/2018 11:22 pmQuote from: Lars-J on 11/27/2018 11:10 pmIt's not the size that worries me (it is unknown), it is the proportions of propellant tanks to airframe. This is thing will have a very bad dry mass ratio.Does a high dry mass ratio on the 1st stage really matter that much though? It isn't an SSTO. If you are having problems wrapping your head around the concept, just consider it air launch but the airplane is rocket powered, not air breathing, and flies much faster than a normal sub-sonic air launch scenario that would normally require 2 stages+ after that.Oh I can wrap my head around the concept just fine, it just looks so inefficient.
Quote from: Lars-J on 11/27/2018 11:26 pmQuote from: ncb1397 on 11/27/2018 11:22 pmQuote from: Lars-J on 11/27/2018 11:10 pmIt's not the size that worries me (it is unknown), it is the proportions of propellant tanks to airframe. This is thing will have a very bad dry mass ratio.Does a high dry mass ratio on the 1st stage really matter that much though? It isn't an SSTO. If you are having problems wrapping your head around the concept, just consider it air launch but the airplane is rocket powered, not air breathing, and flies much faster than a normal sub-sonic air launch scenario that would normally require 2 stages+ after that.Oh I can wrap my head around the concept just fine, it just looks so inefficient.What is the alternative? If it masses X dry, the landing gear can land at speed Y, you need to generate Z lift roughly equal to X mass at speed <Y. If these constraints aren't followed, you slam into the runway and you would much better off just using a Firefly Alpha/Beta. Big wings also have the affect of spreading out the thermal load over a greater amount of TPS, meaning it might last for more flights.
