brtly
New Member
Posts: 2
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Post by brtly on Dec 23, 2020 0:50:49 GMT -8
Hi, I am going to build a 180mm batch rocket sidewinder with a floor channel.On the website batchrocket.eu, it is stated that the vertical part should be 5,4% of the cross-section of the heat riser. In this case, that comes to 9,72.(5,4 % of 180). What is this ? square mm? In the calculator it is staled that the P-channel should be 65x20, if we take a tube of 60 x 30, the inner diameter is 56x 24, makes 1296mm2. For the vertical part I have a tube of 35 x 35mm, inner diameter 24 x 24, which probably isn't enough. I want to mention that I designed a kind of air wash channel to keep the glass clear, so that will create an extra inlet and will -hopefully- contribute to a good turbulence for air and fire mix. Ca anyone bring some clarity? Thanks Bart
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Post by Karl L on Dec 23, 2020 1:23:07 GMT -8
You're calculating 5.4% of the linear dimension. What you need is 5.4% of the area:
5.4% x 180 X 180 = ~1750 mm2 (mm squared).
To find the square having this area take the square root. This is a ~42mm square, so the vertial square tube should be 42mm inside.
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brtly
New Member
Posts: 2
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Post by brtly on Dec 23, 2020 2:11:41 GMT -8
You're calculating 5.4% of the linear dimension. What you need is 5.4% of the area: 5.4% x 180 X 180 = ~1750 mm2 (mm squared). To find the square having this area take the square root. This is a ~42mm square, so the vertial square tube should be 42mm inside. Thanks Karl!!
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Post by peterberg on Dec 23, 2020 7:14:12 GMT -8
I am going to build a 180mm batch rocket sidewinder with a floor channel.On the website batchrocket.eu, it is stated that the vertical part should be 5,4% of the cross-section of the heat riser. In this case, that comes to 9,72.(5,4 % of 180). What is this ? square mm? You assume it's cross-section, i.e. diameter. But in fact it's cross section area, which means it's PI R² for a round riser. In your case it's roughly 3.14 x 90 x 90 mm and 5.4% of the result. Calculated it for you, it's 1374 mm² so the tube should be 37x37 mm inside. Sorry to say, Karl L's calculation isn't correct since he assumes it's a square riser. Risers like that should be treated like a round one while the diameter is equal to one of the sides of the square. batchrocket.eu/en/building#dimension, third alinea. In the calculator it is staled that the P-channel should be 65x20, if we take a tube of 60 x 30, the inner diameter is 56x 24, makes 1296mm2. For the vertical part I have a tube of 35 x 35mm, inner diameter 24 x 24, which probably isn't enough. No, that 24x24 mm isn't even large enough for a 150 mm system. You are mixing up the P-channel and floor channel dimensions here. This would be a major mistake, since the recommended horizontal part of the floor channel should be twice as large as the vertical part. Please read the article about this channel carefully, especially the amendment of 01/05/2019. batchrocket.eu/en/designs#floorchannelI want to mention that I designed a kind of air wash channel to keep the glass clear, so that will create an extra inlet and will -hopefully- contribute to a good turbulence for air and fire mix. I am very curious how you plan to measure the results of your specially designed air wash channel. More to the point: what makes you think your design sidestep would provide better mixing of air and combustibles as compared to the original design?
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