Check this out https://www1.grc.nasa.gov/facilities/htf/ https://www1.grc.nasa.gov/facilities/htf/ Back in the day they could test up to Mach 7. Not it is a tes

Check this out https://www1.grc.nasa.gov/facilities/htf/ https://www1.grc.nasa.gov/facilities/htf/ Back in the day they could test up to Mach 7. Not it is a test bed for hybrid electric planes.