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Sounds like an airboat hovercraft or some other type of propeller driven
ground effect vehicle Actually it sounds closer to something like a skateboard with as prop motor and a user on it. you are missing a huge amount of variables and for props, pitch, density altitude, motors, and at speeds that slow your in the wrong group because very few things, If Any, in any of these groups fly at that speed. And aircraft move slow taxiing because they are not meant to be ground vehicles they usually have very narrow stances and high centers of gravity compared to a ground vehicle as soon as they have any kind of airspeed they want to fly. Look up an RC or Aeronautical engineering group on usenet or elsewhere. you need to find design people not pilots "Flaps_50!" wrote in message ... On Feb 4, 11:55 am, John Doe wrote: Is there such a calculation/formula? How can you tell what propeller to use, how fast it should rotate, and how much weight it can push along the ground? Specifically... I would like to tell what sort and size of propeller rotating at what speed, in calm air to push 100 or 200 pounds on smooth and level pavement with zero rolling resistance to about 20 mph. 20 mph is too fast for taxying. What are you asking about -zero rolling resistance???? Cheers |
#2
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On Feb 5, 8:56*am, "Brent" wrote:
Sounds like an airboat hovercraft or some other type of propeller driven ground effect vehicle Actually it sounds closer to something like a skateboard with as prop motor and a user on it. you are missing a huge amount of variables and for props, pitch, density altitude, motors, and at speeds that slow your in the wrong group because very few things, If Any, in any of these groups fly at that speed. And aircraft move slow taxiing because they are not meant to be ground vehicles they usually have very narrow stances and high centers of gravity compared to a ground vehicle as soon as they have any kind of airspeed they want to fly. Look up an RC or Aeronautical engineering group on usenet or elsewhere. you need to find design people not pilots "Flaps_50!" wrote in message ... On Feb 4, 11:55 am, John Doe wrote: Is there such a calculation/formula? How can you tell what propeller to use, how fast it should rotate, and how much weight it can push along the ground? Specifically... I would like to tell what sort and size of propeller rotating at what speed, in calm air to push 100 or 200 pounds on smooth and level pavement with zero rolling resistance to about 20 mph. 20 mph is too fast for taxying. What are you asking about -zero rolling resistance???? Cheers To add a little to this: zero rolling resistance means all that has to be overcome is aerodynamic drag, and one needs to know something about the shape of what is being moved. Air weighs about 0.08 pounds a cubic foot, you simply have to decide how long you want to take to get to whatever speed, that will tell you the force you need. F still equals mass times accelerations, so then for any diameter prop there is a certain rotation speed that'll throw aft the required mass of air. The lower limit on prop diameter will have to do with keeping the tip speeds sub sonic, the upper limit is related to mechanical factors. I seem to remember props in general are about 30% efficient, if that guess is true and you need 1 horsepower delivered you'll need an engine that produces something over 3. Why do I feel I'm answering someone's homework question? |
#3
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a pappson gmail.com wrote:
On Feb 5, 8:56˙am, "Brent" b_phil... hotmail.com wrote: Sounds like an airboat hovercraft or some other type of propeller driven ground effect vehicle Actually it sounds closer to something like a skateboard with as prop mot or and a user on it. you are missing a huge amount of variables and for prop s, pitch, density altitude, motors, and at speeds that slow your in the wron g group because very few things, If Any, in any of these groups fly at that speed. And aircraft move slow taxiing because they are not meant to be ground vehicles they usually have very narrow stances and high centers of gravit y compared to a ground vehicle as soon as they have any kind of airspeed th ey want to fly. Look up an RC or Aeronautical engineering group on usenet or elsewhere. y ou need to find design people not pilots "Flaps_50!" morefl... gmail.com wrote in message news:fcb480ce-e285-47c4-87dc-8a9257583974 o7g2000prn.googlegroups.com... On Feb 4, 11:55 am, John Doe j... usenetlove.invalid wrote: Is there s uch a calculation/formula? How can you tell what propeller to use, how fast it should rotate, and how much weight it can push along the ground? Specifically... I would like to tell what sort and size of propeller rotating at what speed, in calm air to push 100 or 200 pounds on smooth and level pavement with zero rolling resistance to about 20 mph. 20 mph is too fast for taxying. What are you asking about -zero rolling resistance???? Cheers To add a little to this: zero rolling resistance means all that has to be overcome is aerodynamic drag, and one needs to know something about the shape of what is being moved. Air weighs about 0.08 pounds a cubic foot, you simply have to decide how long you want to take to get to whatever speed, that will tell you the force you need. F still equals mass times accelerations, so then for any diameter prop there is a certain rotation speed that'll throw aft the required mass of air. The lower limit on prop diameter will have to do with keeping the tip speeds sub sonic, the upper limit is related to mechanical factors. I seem to remember props in general are about 30% efficient, if that guess is true and you need 1 horsepower delivered you'll need an engine that produces something over 3. Why do I feel I'm answering someone's homework question? Maybe because you are a Google Groups user. -- see also Google Groups Path: news.astraweb.com!border6.newsrouter.astraweb.com! npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!postnews.google.com!r21g2000yqd.googlegr oups.com!not-for-mail From: a pappson gmail.com Newsgroups: rec.aviation.military,rec.aviation.piloting,rec.av iation.homebuilt Subject: Taxi calculator? (propeller type and speed, aircraft weight, taxi speed) Date: Sat, 5 Feb 2011 10:35:18 -0800 (PST) Organization: http://groups.google.com Lines: 56 Message-ID: 8f08b3ad-a0c3-4b20-857b-14c22081bca6 r21g2000yqd.googlegroups.com References: 4d4b324f$0$26911$c3e8da3$33881b6a news.astraweb.com fcb480ce-e285-47c4-87dc-8a9257583974 o7g2000prn.googlegroups.com iijkv3$9c7$1 news.eternal-september.org NNTP-Posting-Host: 174.109.180.208 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Trace: posting.google.com 1296930918 1624 127.0.0.1 (5 Feb 2011 18:35:18 GMT) X-Complaints-To: groups-abuse google.com NNTP-Posting-Date: Sat, 5 Feb 2011 18:35:18 +0000 (UTC) Complaints-To: groups-abuse google.com Injection-Info: r21g2000yqd.googlegroups.com; posting-host=174.109.180.208; posting-account=wyGAFgoAAACOdZRjCqGm4sY24S8zhtSL User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13,gzip(gfe) |
#4
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On Feb 6, 2:56*am, "Brent" wrote:
Sounds like an airboat hovercraft or some other type of propeller driven ground effect vehicle Actually it sounds closer to something like a skateboard with as prop motor and a user on it. you are missing a huge amount of variables and for props, pitch, density altitude, motors, and at speeds that slow your in the wrong group because very few things, If Any, in any of these groups fly at that speed. And aircraft move slow taxiing because they are not meant to be ground vehicles they usually have very narrow stances and high centers of gravity compared to a ground vehicle as soon as they have any kind of airspeed they want to fly. Look up an RC or Aeronautical engineering group on usenet or elsewhere. you need to find design people not pilots "Flaps_50!" wrote in message ... On Feb 4, 11:55 am, John Doe wrote: Is there such a calculation/formula? How can you tell what propeller to use, how fast it should rotate, and how much weight it can push along the ground? Specifically... I would like to tell what sort and size of propeller rotating at what speed, in calm air to push 100 or 200 pounds on smooth and level pavement with zero rolling resistance to about 20 mph. 20 mph is too fast for taxying. What are you asking about -zero rolling resistance???? We taxied at 'walking pace' which meant sometimes a little faster to make a gate or taxiway :-) |
#5
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"Brent" b_philion hotmail.com wrote:
Sounds like an airboat hovercraft or some other type of propeller driven ground effect vehicle Actually it sounds closer to something like a skateboard with as prop motor and a user on it. you are missing a huge amount of variables and for props, pitch, density altitude, motors, and at speeds that slow your in the wrong group "that slow your" = "that show you are" ? because very few things, If Any, in any of these groups fly at that speed. And aircraft move slow taxiing because they are not meant to be ground vehicles they usually have very narrow stances and high centers of gravity compared to a ground vehicle as soon as they have any kind of airspeed they want to fly. Look up an RC or Aeronautical engineering group on usenet or elsewhere. you need to find design people not pilots Or someone who can at least write... -- "Flaps_50!" moreflaps gmail.com wrote in message news:fcb480ce-e285-47c4-87dc-8a9257583974 o7g2000prn.googlegroups.com... On Feb 4, 11:55 am, John Doe j... usenetlove.invalid wrote: Is there such a calculation/formula? How can you tell what propeller to use, how fast it should rotate, and how much weight it can push along the ground? Specifically... I would like to tell what sort and size of propeller rotating at what speed, in calm air to push 100 or 200 pounds on smooth and level pavement with zero rolling resistance to about 20 mph. 20 mph is too fast for taxying. What are you asking about -zero rolling resistance???? Cheers Path: news.astraweb.com!border6.newsrouter.astraweb.com! news.glorb.com!news2.glorb.com!eternal-september.org!feeder.eternal-september.org!.POSTED!not-for-mail From: "Brent" b_philion hotmail.com Newsgroups: rec.aviation.military,rec.aviation.piloting,rec.av iation.homebuilt Subject: Taxi calculator? (propeller type and speed, aircraft weight, taxi speed) Date: Sat, 5 Feb 2011 08:56:39 -0500 Organization: A noiseless patient Spider Lines: 37 Message-ID: iijkv3$9c7$1 news.eternal-september.org References: 4d4b324f$0$26911$c3e8da3$33881b6a news.astraweb.com fcb480ce-e285-47c4-87dc-8a9257583974 o7g2000prn.googlegroups.com Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit Injection-Date: Sat, 5 Feb 2011 13:56:51 +0000 (UTC) Injection-Info: mx02.eternal-september.org; posting-host="xYLfF8Lb0bp2wp8oENpIHA"; logging-data="9607"; mail-complaints-to="abuse eternal-september.org"; posting-account="U2FsdGVkX1+B/Bq5SBEMU+t3/WD5HnKQIqjXJoitkek=" X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18483 In-Reply-To: fcb480ce-e285-47c4-87dc-8a9257583974 o7g2000prn.googlegroups.com X-Newsreader: Microsoft Windows Mail 6.0.6001.18416 Cancel-Lock: sha1:EC3Z+JO44uhq890OIgPBe02FbqM= X-Priority: 3 X-MSMail-Priority: Normal |
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