Lester Hope, you're my hero.
Actually, I don't know if you are or not, but I'm willing to take a small punt that you know what you're doing.
Great to see the article on you in the Marlborough Express and to see the effort you've put into developing a frost fan blade.
Lester, I'm no expert, but I've had an opportunity to take note of a frost fan blade or two in my time, and I think you're on the right track. From the small picture in the paper, it is obvious that you understand something that some other manufacturers have missed. Aerodynamics matter.
Your design and that of the Frost Boss C-49 display an understanding of the principle that a frost fan blade is designed to operate at a specific speed and the airflow at that speed has specific properties.
This is where the older traditional fans with their essentially flat blades were pretty crude. The Defender with its aerofoil shape recognized that aerodynamics plays a part, but they failed to pick up the importance of the change in velocity along the length of the blade.
You clearly know what you are doing and I applaud you. Well done.
If you haven't done so yet, please get some acoustic testing carried out and if it's worth crowing about, let us know.
Good on you.
4 comments:
Thanks for bringing this news to our attention ... what an awesome way to fight frost ... but me thinks the early birds should wait for the sun to be well and truly up and beaming, before looking for worms.
Your second link is a scream ... their by-line is "Firearms not politics". Read some of the reader's comments ... there are some wags out there.
The picture of the 3 microwave towers in the Ontario vineyard doesn't look like a very big test site. The towers are 25' tall, so the distance between the towers looks about 60'. That makes an area of about 200 sq.m inside the perimeter of the towers .... and I suspect not all that area gets nuked ... maybe only 3/4 of it. So it's a piddly test area really. This would equate to about 1/50 to 1/70 th of a hectare. And I would imagine you would need about 6 kW of power to run these 3 microwave emitters. That makes 6 kW times 50 which equals 300 kW of power per hectare. Man, that's a lot of power ... you won't get that from the mains power line at the end of the road. So you will need a diesel genset ... a BIG diesel genset ... like 3,000 kW for every 10 hectares ... that's a 4,000 hp engine at 100% efficiency ... so maybe closer to 4,500 hp would be more realistic. And that's just for 10 ha, which is a little more than one frost fan can cover.
So the claims of this system being silent are bit misleading ... the monstrous diesel gensets will put paid to that ... let alone the huge cost of diesel to run the microwave system.
Thanks for the comment. I presume that you meant to post it against the Painless frost protection (http://frostfans.blogspot.com/2010/06/painless-frost-protection.html) blog?
The firearms link is a hoot! Hence the "Painless frost protection" dig.
I concur totally, the power requirements are not in-significant. Probably more than the electrical heater wire trialled here http://frostfans.blogspot.com/2009/11/that-man-deserves-methodes.html .
Having said that acoustically insulating a generator is always easier than a frost fan. I would be inclined to support the effort in its development phase and reserve judgement till a practical system is announced. Ultimately their heart is in the right place. (if not slightly warmed up)
By gum ... you are so right ... can you switch my comment across to the correct microwave item and pop an "a" in the last sentence just before the "bit misleading". Thanks.
Welcome.
Thanks for your comments. Always good to have a technical head do the math.
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