Six year old me sent an idea to McDonnell Douglas for an airplane with turboprops to back up the jets in case of engine fire. There was also a fire suppression system. They sent me some nice brochures about the DC-8, -9, and -10, but looking back on it they could have mentioned that the jets are already redundant and will usually stop burning when the fuel is cut.

I hope they at least acknowledge that it was quite impressive for a six year old to understand the distinction between different types of engine and consider engine fires.

Anyway, YC's Heart Aerospace's intended commercial airframe design now does use a turboprop as a backup (for range extension beyond the capabilities of their battery electric engine), so six year old you was clearly onto something :)

> usually