7 ms·

> Don't model rockets routinely go much higher than the 400 feet the FAA has traditionally limited hobby aircraft to? Even if they do, they're mostly cardboard

by eck 12y ago

> Don't model rockets routinely go much higher than the 400 feet the FAA has traditionally limited hobby aircraft to? Even if they do, they're mostly cardboard, whereas model airplanes have things like small engine blocks. I bet a 737 engine could ingest a model rocket without anyone noticing.

jsmthrowaway 12y ago
You'd be surprised. Jet engines are designed to be robust against some really crazy scenarios (I'm amazed a jet engine continues to function during the water injection tests I've seen), but all it takes is one blade failure -- with many to choose from in various places in the engine -- and it's game over. One can imagine many ingestions that might cause a blade failure, because the rotating fans in a jet engine are very high energy environments. With the right alignment of planets and hitting just right, a model rocket might cause a failure. It all depends and is hard to predict. Most people would predict modern engines as likely to survive ingestion of geese, but then we had US 1549 (and a USAF E-3 at Elmendorf before it). Even though the FAA has engine manufacturers like GE test the hell out of engines, it's tough to predict what will happen in the real world. Birds are a huge threat to aviation, both engine ingestion and windscreen collisions, and birds are mostly organic. (It goes without saying to stand the hell away from an operating jet engine even at idle, too, because humans do get ingested with fatal results.) I can't imagine an operating engine ingesting a drone or anything else with non-organic components would go well, and this is why I always advocate very strongly for safe drone operation. Here's an intentional intake blade failure to ascertain whether the engine can contain the failure without threatening the aircraft; this is useful to see what happens if something is ingested that causes a catastrophic blade failure: https://www.youtube.com/watch?v=WAhjSviYVr8 https://www.youtube.com/watch?v=WAhjSviYVr8

by eck 12y ago

jsmthrowaway 12y ago

You'd be surprised. Jet engines are designed to be robust against some really crazy scenarios (I'm amazed a jet engine continues to function during the water injection tests I've seen), but all it takes is one blade failure -- with many to choose from in various places in the engine -- and it's game over. One can imagine many ingestions that might cause a blade failure, because the rotating fans in a jet engine are very high energy environments. With the right alignment of planets and hitting just right, a model rocket might cause a failure. It all depends and is hard to predict. Most people would predict modern engines as likely to survive ingestion of geese, but then we had US 1549 (and a USAF E-3 at Elmendorf before it). Even though the FAA has engine manufacturers like GE test the hell out of engines, it's tough to predict what will happen in the real world. Birds are a huge threat to aviation, both engine ingestion and windscreen collisions, and birds are mostly organic. (It goes without saying to stand the hell away from an operating jet engine even at idle, too, because humans do get ingested with fatal results.) I can't imagine an operating engine ingesting a drone or anything else with non-organic components would go well, and this is why I always advocate very strongly for safe drone operation. Here's an intentional intake blade failure to ascertain whether the engine can contain the failure without threatening the aircraft; this is useful to see what happens if something is ingested that causes a catastrophic blade failure: https://www.youtube.com/watch?v=WAhjSviYVr8 https://www.youtube.com/watch?v=WAhjSviYVr8