{"id":3088,"date":"2014-07-24T20:00:42","date_gmt":"2014-07-24T20:00:42","guid":{"rendered":"https:\/\/blokland.net\/wp\/?p=3088"},"modified":"2014-07-26T16:01:37","modified_gmt":"2014-07-26T16:01:37","slug":"sounds-of-silence","status":"publish","type":"post","link":"https:\/\/blokland.net\/wp\/sounds-of-silence\/","title":{"rendered":"Sounds of silence"},"content":{"rendered":"

\"IMG_20140723_181917\"<\/a>Finally got a 3 blade prop, because of availability I selected an Elster 26*12<\/a>. \u00a0Thanks to\u00a0the nice sunny weather I was able to do some \u00a0empty field noise tests. \u00a0The plane was placed at the center of the field. The air temp was 30C, wind between 2 and 4 m\/s. Humidity around 80%. I performed 4 measurements at 25 meter distance, placed at 90 degrees around the plae. \u00a0Of course it would have been nice to have the plane sitting 1 meter high, but that’s impossible without a lot of effort. Rear of the plane: 68-70 \u00a0dBA, Front, 80-82 dBA, left and right in line with the prop also 79-82 dB. I only ran to engine to max rpm long enough to get a stable dB reading. \u00a0RPM readings (per Jeti) were 5760). As with all these measurements, it is very inaccurate, it produces nothing more than a guestimate. (Meter +\/- 2 dB, wind, geese you name it..) The only way to really measure is in a ”dead” room, and that’s not going to happen. This is all about getting some kind of feel \u00a0for ”is it loud or not”. So my average would be between 77-79 dBA. at 25 meter. I feel that this is quite acceptable, when I compare it to some of our small electric models. (mine is quieter!) A single flight was performed, and I can honestly say that many times I could not hear the sound of the engine when flying less then full throttle. From the previous post:<\/p>\n

..72 dB at 25 meters in front of the plane, but 84 at 90 degrees, in line with the prop. This is with a Mejzlik 28*10 2 blade, running at 6150 RPM (temp =20C or thereabouts). In the air I see values of almost 7000 RPM,<\/p><\/blockquote>\n

So in short, switching to a 3 blade cuts down the noise by half (-3 dB) and costs me 400 RPM. \u00a0Performance wise I think I am ok. I still run the engine on the rich side, it needs further tweeking. (I’m forever tweaking, so what’s new?)<\/p>\n","protected":false},"excerpt":{"rendered":"

Finally got a 3 blade prop, because of availability I selected an Elster 26*12. \u00a0Thanks to\u00a0the nice sunny weather I was able to do some \u00a0empty field noise tests. \u00a0The plane was placed at the center of the field. The air temp was 30C, wind between 2 and 4 m\/s. Humidity around 80%. I performed … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":3091,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-3088","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-carden"],"_links":{"self":[{"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/posts\/3088","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/comments?post=3088"}],"version-history":[{"count":0,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/posts\/3088\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/media\/3091"}],"wp:attachment":[{"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/media?parent=3088"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/categories?post=3088"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blokland.net\/wp\/wp-json\/wp\/v2\/tags?post=3088"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}