Wikipedia:Reference desk/Archives/Science/2023 September 22

= September 22 =

Mucosal layer peeling off
I've noticed that when my soft palate is scalded with some hot meal, there's a feeling of some mucosal layer peeling off or shrinking in the affected area. How that layer and related process is called anatomically/physiologically (other than thermal burn)? 212.180.235.46 (talk) 12:30, 22 September 2023 (UTC)


 * See oral mucosa and, more generally, mucous membrane. We cannot provide medical advice, but if you think your mouth has been injured, a visit to your doctor is in order. Matt Deres (talk) 17:44, 22 September 2023 (UTC)

Bell AH-1 Expert arround? Why a wide-chord rotor blade?
The fact that when the Bell AH-1 was created, "components of the Bell 204 UH-1 were used as far as possible" to keep costs low (for example, rotor, gearbox and turbines) can be read widely distributed in many places within Wikipedia.

However, why exactly a special rotor blade was developed for the Cobra is nowhere explained. Perhaps an expert reads this and spends some time for an educated statement?

Thanks in Advance --46.114.5.151 (talk) 14:56, 22 September 2023 (UTC)
 * It appears that the wide-chord rotor in general was being adopted at that time, as it provided more stability. Abductive  (reasoning) 21:52, 22 September 2023 (UTC)
 * Googling around, it seems that the UH-1C (developed immediately before the AH-1 but only 750 were built) also had wide-chord blades, intended to increase speed. I couldn't pin down whether exactly the same rotors were used on both, or if those used on the AH-1 were a further development. Other sources state that wide blades are quieter as well. Alansplodge (talk) 18:23, 25 September 2023 (UTC)
 * Universal principles show that the planform area of a wing or rotor is largely determined by the weight of the aircraft/helicopter. Noise levels and general flying qualities of a helicopter are partly determined by the airspeed of the tip of the advancing blade. If two different helicopters have the same maximum weight but different maximum speeds, they will have the same rotor blade planform area but the faster of the two must have a smaller rotor diameter if the two are to have the same blade tip speed when flying at maximum speed; this dictates that the faster helicopter must have blades with a wider chord, or a greater number of blades.
 * The UH-1 and AH-1 have the same maximum take-off weight - 9,500 lb. The UH-1 has a maximum forward speed of 110 knots and a rotor diameter of 48 ft. In the case of the AH-1, these parameters are 149 knots and 44 ft. Seeing both helicopters have the same number of blades, the wider chord of the AH-1 blade is exactly what is expected from these universal principles. Dolphin ( t ) 22:35, 25 September 2023 (UTC)

Attention deficit disorder
What is the difference between attention deficit disorder (ADD) and attention deficit hyperactivity disorder? Why does Wikipedia only have a single page for both and say only that ADD was an older name of ADHD? 207.114.136.166 (talk) 21:02, 22 September 2023 (UTC)


 * Wikipedia say that ADD was an older name of ADHD because it was. There is no difference. AndyTheGrump (talk) 21:15, 22 September 2023 (UTC)