Mushroom Model Publication [MMP] new book on the Bartel BM-4 is now out on sale
This is partial text from the full article (usually with photos) at https://aeroscale.net/news/new-book-bartel-bm-4-out-now
This is partial text from the full article (usually with photos) at https://aeroscale.net/news/new-book-bartel-bm-4-out-now