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Boom (YC W16) – Supersonic Passenger Airplanes

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Re: Boom (YC W16) – Supersonic Passenger Airplanes

#301

Post by WatchDog »

schwarrrtz wrote: post #245
btilly wrote: post #240

Earlier quoted context omitted.

Elon Musk says that eventually we will move to VTOL supersonic electric jets, but he is too busy with other projects to implement it. Have you thought about this idea, and in what time frame do you think someone might try to implement it? Elon's basic idea is that air-breathing jets are limited to altitudes at which oxygen tops out, and then are mostly fighting drag from nitrogen. Electric ones can go to higher altit…

The specific energy of kerosene is ~40 MJ/kg [0] while the specific energy of lithium ion batteries is ~1 MJ/kg [1]. Unsure how much energy you'd save from the difference in drag, but I'd guess that significant improvements in electric energy storage would be required to make an electric plane doable. [0] https://en.wikipedia.org/wiki/Kerosene#Properties [1] https://en.wikipedia.org/wiki/Lithium-ion_battery

Plus a conventional airplane sheds weight as it travels.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#302

Post by astrodust »

Animats wrote: post #300
bscholl wrote: post #192

Hi - I'm Blake, Founder/CEO at Boom. After watching no tangible progress in supersonics since Concorde was shut down, I started Boom because I want supersonic flight in our lifetime. Not just as a private jet, but something most anyone can afford to fly. Will try to answer as many questions here as I can.

1. How much money do you need to get to first flight? 2. How much money do you have?

Or more accurately: How many cargo containers full of money do you have?

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#303

Post by Animats »

There's Aerion.[1] They were going to build an 8-passenger supersonic bizjet. Top speed Mach 1.5, cruise Mach 1.4, price $120 million, first flight planned for 2021. They're still talking about where to build the factory, but they're already taking pre-orders.

[1] http://www.aerionsupersonic.com/

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#304

Post by bvi »

bscholl wrote: post #192

Hi - I'm Blake, Founder/CEO at Boom. After watching no tangible progress in supersonics since Concorde was shut down, I started Boom because I want supersonic flight in our lifetime. Not just as a private jet, but something most anyone can afford to fly. Will try to answer as many questions here as I can.

Honest / naive question. How do you even start an aerospace company "in your basement"?

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#305

Post by manarth »

jonknee wrote: post #268
nether wrote: post #227

Earlier quoted context omitted.

How many people did SpaceX start with? Certainly not the thousands of workers it has today. Everything you said about requiring a "national scale corp" was said about launching rockets to orbit as well. Looking at Boom's roster they have some seriously experienced industry vets working for them or advising them. This isn't just fresh grads. They've been through FAA/EASA cert trials of new aircraft, testing and unders…

SpaceX has also had a lot of stuff blow up. That's fine with a rocket, but it's a company killer with a new plane.

SpaceX has also had a lot of [issues commensurate with the nature of their industry]. That's fine with a rocket, [and also fine with a new airplane, as long as the issues are proportionate with what is common in their industry].

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#306

Post by salbri »

Hey Blake, I'm Salim. I like what you guys are doing :)

Interested in understanding more about how you plan to tackle cooling and heating when gaining altitude and hitting supersonic speeds respectively through materials different to the Aluminium used on the Concorde (you mentioned carbon fiber), which considering you're planning on reaching M3 will be important

Also interested in understanding more about what you're base case assumption for affordability is / what mitigants you've put in place for any change in these assumptions (rise in oil prices, airlines being able to charge crazy amounts due to product exclusivity (clearly will be just a handful of player who have access to this engineering in our life time I imagine) etc...). Would be nice to hear a bit about what engineering thinking has gone into the cost saving..are we still looking at the same delta wing we saw previously?

From what I've seen so far very cool and exciting - look forward to following your story!

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#307

Post by mikeyouse »

schwarrrtz wrote: post #245
btilly wrote: post #240

Earlier quoted context omitted.

Elon Musk says that eventually we will move to VTOL supersonic electric jets, but he is too busy with other projects to implement it. Have you thought about this idea, and in what time frame do you think someone might try to implement it? Elon's basic idea is that air-breathing jets are limited to altitudes at which oxygen tops out, and then are mostly fighting drag from nitrogen. Electric ones can go to higher altit…

The specific energy of kerosene is ~40 MJ/kg [0] while the specific energy of lithium ion batteries is ~1 MJ/kg [1]. Unsure how much energy you'd save from the difference in drag, but I'd guess that significant improvements in electric energy storage would be required to make an electric plane doable. [0] https://en.wikipedia.org/wiki/Kerosene#Properties [1] https://en.wikipedia.org/wiki/Lithium-ion_battery

To be fair to our electric friends, electric motors are >90% efficient while turbofans top out at somewhere near 35% efficiency (as far as I can find).. So what appears to be a 40:1 advantage to kerosene is more like a 15:1 advantage -- substantial but much more accessible with ongoing battery improvements. Though as another commenter mentioned, fuel planes do definitely benefit from shedding weight the entire time they're moving.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#308

Post by [deleted] »

schiffern wrote: post #280
schwarrrtz wrote: post #245

Earlier quoted context omitted.

The specific energy of kerosene is ~40 MJ/kg [0] while the specific energy of lithium ion batteries is ~1 MJ/kg [1]. Unsure how much energy you'd save from the difference in drag, but I'd guess that significant improvements in electric energy storage would be required to make an electric plane doable. [0] https://en.wikipedia.org/wiki/Kerosene#Properties [1] https://en.wikipedia.org/wiki/Lithium-ion_battery

And yet Musk claims transcontinental range (NY-LA) would be possible with 400 Wh/kg batteries and mid-70% battery mass fraction. http://www.aviation.com/general-aviation/elon-musk-toying-de...

[deleted]

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#309

Post by schwarrrtz »

schiffern wrote: post #280
schwarrrtz wrote: post #245

Earlier quoted context omitted.

The specific energy of kerosene is ~40 MJ/kg [0] while the specific energy of lithium ion batteries is ~1 MJ/kg [1]. Unsure how much energy you'd save from the difference in drag, but I'd guess that significant improvements in electric energy storage would be required to make an electric plane doable. [0] https://en.wikipedia.org/wiki/Kerosene#Properties [1] https://en.wikipedia.org/wiki/Lithium-ion_battery

And yet Musk claims transcontinental range (NY-LA) would be possible with 400 Wh/kg batteries and mid-70% battery mass fraction. http://www.aviation.com/general-aviation/elon-musk-toying-de...

A 70% battery mass fraction seems like a huge engineering challenge for an aircraft. I did a quick calculation of fuel mass fraction for the various Boeing 777 models [0] which ranged from ~13% to ~36%.

Not saying it's impossible. Just hard.

[0] https://en.wikipedia.org/wiki/Boeing_777#Specifications

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#310

Post by zevets »

Animats wrote: post #303

There's Aerion.[1] They were going to build an 8-passenger supersonic bizjet. Top speed Mach 1.5, cruise Mach 1.4, price $120 million, first flight planned for 2021. They're still talking about where to build the factory, but they're already taking pre-orders. [1] http://www.aerionsupersonic.com/

Since the founder is in the thread, why did they target cruise > Mach 2 and a 40 passenger size? The business jet segment makes a lot of sense for high speed flight, but this seems like more of a stretch.
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