# Scramjets? Why do we need a jet that goes Mach 10? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 17, 2004, 2:49pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266 "2004-11-17T14:49:57Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [November 18, 2004, 12:38am UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/21 "2004-11-18T00:38:19Z")
> [@](#): > > , then up to mach 3 on ramjet power. > > Scramjets take the craft from mach 3 to 10. I though a scramjet ment supersonic ramjet, if so then over mach 1 it would be a scramjet, wouldn’t it? ---
**Author:** ![Hyperelastic](https://avatars.discourse-cdn.com/v4/letter/h/a3d4f5/32.png) [@Hyperelastic](https://boards.straightdope.com/u/Hyperelastic)\ **Post date:** [November 18, 2004, 1:15am UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/22 "2004-11-18T01:15:37Z")
> [@kanicbird](#): > > I though a scramjet ment supersonic ramjet, if so then over mach 1 it would be a scramjet, wouldn’t it? The “supersonic” refers to the combustion, not the vehicle speed. Other jets, even plain ramjets, combust at subsonic conditions (a shock wave develops ahead of the combustion). Combustion at supersonic speeds is more efficient, having to do with using the kinetic energy that would have been lost in passing through the shock, but I’d better leave the details to a physical chemist. ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [November 18, 2004, 2:11am UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/23 "2004-11-18T02:11:03Z")
1. While looking through the DARPA web site, one of the request for proposals included a study for what it would take to implement a CONUSA (continental US) based bomber) with a combat radius of anywhere in the world within _two hours_. 2. The principle reason for the flight was to get some real “outdoor” data as opposed to a laboratory setting. There are, of course, theorectical models, but to validate these assumptions you need to collect empirical data. For the regions that involved Mach 7+ this the first time we’ve ever collected _any_ information as it’s just too difficult to replicated in the lab for an air-breathing machine. ---
**Author:** ![Unintentionally\_Blank](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unintentionally_blank/32/5418_2.png) [@Unintentionally\_Blank](https://boards.straightdope.com/u/Unintentionally_Blank)\ **Post date:** [November 18, 2004, 4:01am UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/24 "2004-11-18T04:01:41Z")
It ppartly falls under the ‘If you have to ask, I can’t tell you’ frame of mind. Will it lead to more food for our starving kids? Maybe. But only if NASA commits the HUGE amounts of money on Solid Rocket Fuel that the Shuttle currently needs to lift off…or what about the environmental effects of that fuel? smaller-cheaper-LEO means closer to a space elevator which means EXTREMELY cheap trips to space. THAT means a veritable explosion of new metallurgical and medical advances. And where would be be without TANG?\* (\*=yeah, I know, Cece said it wasn’t strictly developed for the astronauts…go with me here.) ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [November 18, 2004, 2:18pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/25 "2004-11-18T14:18:12Z")
> [@Phlosphr](#): > > What are the practical uses? Fed-ex maybe would want one… 🙂 How about traveling from New York to Austrilia, Brazil or Japan in under 18 hours? ---
**Author:** ![Waverly](https://avatars.discourse-cdn.com/v4/letter/w/57b2e6/32.png) [@Waverly](https://boards.straightdope.com/u/Waverly)\ **Post date:** [November 18, 2004, 4:18pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/26 "2004-11-18T16:18:55Z")
> [@The Chao Goes Mu](#): > > We do, in fact, need something that goes Mach 10. We’re now one step closer to traveling close to the speed of light. That’s a mighty small step in the scheme of things. Incidentally, if a light-speed aircraft were leaving JFK this afternoon, and I had a free ticket, I’d give it away to someone who I really didn’t like all that much. To those that think the money could just have easily gone to better lawncare or free happy meals to all the children of the world: Research and development is essential to a healthy economy. Nobel prize winner Solow linked more than 50% of economic growth to new innovations. Don’t develop, don’t grow. ---
**Author:** ![Strainger](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/strainger/32/244_2.png) [@Strainger](https://boards.straightdope.com/u/Strainger)\ **Post date:** [November 18, 2004, 4:23pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/27 "2004-11-18T16:23:26Z")
As an aerospace/mechanical engineer, I’d like to chime in with a simple explanation… Because Mach 10 is really freakin’ fast and fast is cool! Rar! ---
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [November 18, 2004, 5:38pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/28 "2004-11-18T17:38:14Z")
> [@Booker57](#): > > Could you use rail gun tech to get your ship up to the speed needed for the scram to work? Just thinking with the keyboard. No. The acceleration would kill everyone inside. It would be cheaper to just crush them in a large press. ---
**Author:** ![BoringDad](https://avatars.discourse-cdn.com/v4/letter/b/ad7895/32.png) [@BoringDad](https://boards.straightdope.com/u/BoringDad)\ **Post date:** [November 20, 2004, 4:58am UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/29 "2004-11-20T04:58:34Z")
> [@msmith537](#): > > No. The acceleration would kill everyone inside. It would be cheaper to just crush them in a large press. Sure cheaper, but not as dramatic for the evening news. Besides, everyone know that the scramjets from “Supersonic Pizza to the World” will be manned by loveable robots. ---
**Author:** ![Kalhoun](https://avatars.discourse-cdn.com/v4/letter/k/3bc359/32.png) [@Kalhoun](https://boards.straightdope.com/u/Kalhoun)\ **Post date:** [November 22, 2004, 4:17pm UTC](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266/30 "2004-11-22T16:17:41Z")
> [@Hyperelastic](#): > > Why not use the money to buy dollies for all the poor little girls in the world? > > Seriously, NASA’s budget is essentially completely separate from the military’s. It’s not as if every dollar spent by NASA is a dollar taken away from those other worthy causes you mention. The argument you make about priorities could be made equally well in favor of the scramjet research: Why should the government give a [special tax break to importers of Chinese ceiling fans](http://councilfor.cagw.org/site/News2?abbr=CCAGW_&page=NewsArticle&id=8286) instead of spending the money on scientific research? > > The scramjet is a new propulsion technology. The basic idea is that a vehicle that would normally carry its oxygen with it could instead scoop oxygen out of the air and thus increase its efficiency. Like almost any technology, it can be used to help people or kill people. Maybe in 30 years a scramjet-powered vehicle will rush a human heart from the other side of the world to be transplanted into the failing body of some great humanitarian. Ignoring the smartass portion of Hyper’s post, I am for R&D, in general. I am also for space exploration. However, at the moment, there are more pressing needs that the money can be spent on. Learning how to make these vehicles is one thing. Making them (which I assumed is what the OP was talking about) in any capacity beyond research is quite another. [Previous page](https://boards.straightdope.com/t/scramjets-why-do-we-need-a-jet-that-goes-mach-10/275266.md?page=1)