PhilMays Posted November 17, 2006 Share Posted November 17, 2006 Over the past several nights, I have been building a giant conveyer belt in the back yard. Several Neighbors have come over to question. I have been very elusive. I think the fact that I have cages with two animals in each is throwing them! Quote Link to comment Share on other sites More sharing options...
PhilMays Posted November 17, 2006 Share Posted November 17, 2006 Captains Log - November 17, 2006. I am now questioning the reasoning behing building a giant conveyer belt to prove or disprove if an aircraft can fly. I am getting the sick feeling that once the problem is solved that the world will look at me and go "NERD" and tomorrow will be exactly like yesterday. Must....Keep....Building.... Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 17, 2006 Author Share Posted November 17, 2006 NERD!!!!!!!!!!!!!!!!!!!!! But please carry on as there are fellow nerds out in the world and we appreciate your pioneering efforts to expose the Truth... [] I hope your animals are flesh eating... Quote Link to comment Share on other sites More sharing options...
sheltie dave Posted November 17, 2006 Share Posted November 17, 2006 Naw, you're only a professional nerd if you wonder whether the jet will sound best taking off from the Enterprise, the conveyor belt, or the unlimited runway. Then you have serious problems! BTW, which will barbeque a hot dog faster, an F14 or an F15? Quote Link to comment Share on other sites More sharing options...
Andy W Posted November 17, 2006 Share Posted November 17, 2006 No more explanations from me, I promised. Just wanted to say this... I asked my wife this question last night. After about a 1 second pause (it could have been less) she said, "It takes off." I asked her if she were sure. She went through it, thinking out loud, which took another 10 seconds, and she said, "Yes, it takes off. The conveyor doesn't do anything, it just spins the wheels faster." She has never had a calculus class or a physics class, but she does have a 135 I.Q. Now I know that I married the right girl! Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 17, 2006 Share Posted November 17, 2006 "A plane does not accelerate if it does not move from the origin. It will not sustain flight if it does not accelerate and achieve sufficient lift at a combined vector." yes, yes, by george, my weekly check into this thread shows that we are within reach of a conclusion.,...oh, yeah, thats right, the first page of the thread had the same conclusion.....humm...need to draw more pictures. if the prop stops spining while the plane is on a moving belt, the Plane will begin to move backwards with the belt, it will not stay still while the wheels rotate. The wheels rotating has nothing to do with plane flight. Once the prop spins plane movment rearward on the rearward moving belt will stop if the plane forward forces created by the prop are equal to the rearward movement of the belt. At this point the plane will be stationary, prop spinning, wheels spining, but if there is not any forward movement of the wings, plane will not fly. Plane will fly only if forward plane motion exist greater to the backward movment of the belt+the forward force at the distance normally required to lift the pllane. The belt clearly adds drag to the plane.....anything with wheels on a moving belt and it will move with the belt......the item will not remain stationary while the wheels spin. A plane moving backwards on a belt also has lift....but momentum is in the wrong direction....as the props start to spin...lift drops as the momentum decrease.....the zero monetum piont is the point where the plane stopped moving backwards on the belt....now the plane needs enought thrust to begin forward movement equal to the speed of the planes wings needed to create enought lift to get the plane in the air. If however, the belt speed increases with the planes speed and no forward motion of the plane takes place...the plane will not fly. Always remember that a plane on a belt moving rearward will always move rearwards with the belt.....plane will not stay still with wheeels only spining. Remember luke, the force is always with you.....plane will fly only if their is forward motion of the plane. Rule #2, if a pllane is on a belt moving rearward, plane will move rearward also until acted upon by an additional force. Rule #3, as all forces interact....the plane moving rearward on the moving belt.....the prop thrust to bring the plane back to zero momentum.....and the additional thrust needed to overcome the rearward movement of the plane on the rearward moving belt to start forward motion.....forward motion must be greater than that needed to bring the plane back to zero momentum as well as the forward motion needed to start the normal lift process. I'll check back next week.......b ecareful of the dark side. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted November 17, 2006 Share Posted November 17, 2006 I just reread this whole thing, and realized there is another way to look at this. (I was once told by my grandad that being positive about something is being wrong at the top of your voice.) I have been assuming that the plane was already moving forward when the belt began moving backward, and we were just concerned with whether the drag of the belt on the wheel bearings would be enough to "pull" the plane back and prevent it from taking off. And I think the answer to that is "no". However, suppose the plane is *stationary* on the belt when the belt begins to move. Actually, give the belt a head start. Before we turn on the engines, the plane is moving backwards at some speed. As the plane begins to accelerate relative to the belt (and thus slows its rearward speed relative to the ground, but it's still going backwards) the belt begins to speed up. Now what happens? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 17, 2006 Share Posted November 17, 2006 "Before we turn on the engines, the plane is moving backwards at some speed." absolutely correct....also....while the plane moves backward with the belt....there is wing momentum as well as the begining of the lift process due to the wings rearward motion....however...it is in the wrong direction.....once plane props start....thrust begins.....plane reward momentum stops if the thrust is great enough to overcome the reaward momentum (speed of belt is unknown)...when forces are equal...plane is standing still.....thrust now has to increase to be greater then the reaward movement of the belt as well as being enough to continue the forward momentum of the planes wings. Another example....if belt is going rearward 500 miles an hour...and plane can generate only 400 miles of forward momentum...plane will not fly as it is still traveling rearward at 100 miles and hour. If planes needs to reach 70 miles and hour to begin flight....on a belt moving rearward at 500 miles and hour...the thrust of the props has to be enough to put the wings into 570 miles an hour of forward motion before the 70 miles per hour of forward motion needed for flight is acheived. The plane, intself, can not generate enough thrust to put the plane into flight with out forward motion of the wings to start the lift process. Quote Link to comment Share on other sites More sharing options...
sputnik Posted November 17, 2006 Share Posted November 17, 2006 ............The belt clearly adds drag to the plane..... How? Any drag resulting from wheel bearing resistance is negligible in relation to thrust. This is sophomore level engineering mechanics. I've asked this question before, but no one answers. Quote Link to comment Share on other sites More sharing options...
Moderators dtel's wife Posted November 17, 2006 Moderators Share Posted November 17, 2006 Come on I have been very patiently waiting for the answer[] WHAT is the problem?[*-)] Dtel posted on the first page of this thread that the people on this forum were smarter than the people on the other forum?[*-)] Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted November 17, 2006 Share Posted November 17, 2006 Sorry about the car battery, but science marches on, etc... Nothing to be sorry about, I thought it was funny. I am just amazed by how much trust those engines make. Quote Link to comment Share on other sites More sharing options...
Coytee Posted November 17, 2006 Author Share Posted November 17, 2006 Dtel posted on the first page of this thread that the people on this forum were smarter than the people on the other forum?[*-)] Having been a member on that other forum since its inception (actually PRIOR to its inception if you want to be really REALLY technical [], but now we're bending words) I gotta point out, there not only are some bright folks over there (as here), but... I'll put that website against ANY website for mental horsepower & common sense answers. You can take about any question (legitimate), pose it there and within a couple hours, probably have several VERY helpful anwers or suggestions as to the solution. Being a board of tractor owners, the people there are from all spectrums of life (Dr.'s, lawyers, farmers, mechanics, engineers, cops, you name it...), as such, almost regardless of the question, SOMEONE there will have some experience and therefore an idea to the answer. Really is a cool place... I specifically went out of my way to show it to Dtel once (after I saw his tractor). If anyone here is into tractors of any kind... I urge you to go there and actually dig around some. I'll bet you one K-69 tweeter that you'll find it full of good information [] Quote Link to comment Share on other sites More sharing options...
oldenough Posted November 17, 2006 Share Posted November 17, 2006 Sputnik wrote: How? Any drag resulting from wheel bearing resistance is negligible in relation to thrust. This is sophomore level engineering mechanics.I've asked this question before, but no one answers. Sputnik, i think now is the time to give up on this one. Once the light bulb goes on no-one is going to admit at this stage that they are WRONG. But i must admit i would like to be watching the face of the experimenter in the back yard at the moment of truth. Conveyor $100, Plane $20,000, The look on his face.....Priceless Quote Link to comment Share on other sites More sharing options...
ZAKO Posted November 17, 2006 Share Posted November 17, 2006 Ive been in the aircraft design bussines for 35 years And now i see a bunch of monkeys trying to solve the equasion of lift of an aircraft? Geeeeeez !!!!!! Quote Link to comment Share on other sites More sharing options...
DrWho Posted November 17, 2006 Share Posted November 17, 2006 if the prop stops spining while the plane is on a moving belt, the Plane will begin to move backwards with the belt Then the belt will start moving in the forward direction since the belt's speed is in the opposite direction of the motion of the plane. The wheels rotating has nothing to do with plane flight. Correct, and the only thing the conveyor belt is doing is spinning the wheels. The conveyor belt is NOT changing the relative speed of the plane in relation to the air (except for the marginal difference due to friction). Plane will fly only if forward plane motion exist greater to the backward movment of the belt+the forward force Whether or not the plane will fly has absolutely nothing to do with its speed in relation to the belt. It has everything to do with the speed of the plane in relation to the air its travelling through. The belt clearly adds drag to the plane.....anything with wheels on a moving belt and it will move with the belt......the item will not remain stationary while the wheels spin. It will if the forward force from propulsion matches the rearward force of friction. For the plane to not fly is to say that the force of friction is going to exceed the available force of propulsion. If this is the case, then the plane would never take off in the first place. (Keep in mind that friction doesn't really increase with velocity). lift drops as the momentum decrease..... Lift has absolutely nothing to do with momentum. Momentum does not equal Velocity. the zero monetum piont is the point where the plane stopped moving backwards on the belt....now the plane needs enought thrust to begin forward movement equal to the speed of the planes wings needed to create enought lift to get the plane in the air. If the plane was able to stop rearward movement on the belt, then you are claiming the force of propulsion is greater than the force of friction on the tires. This means that the plane will not only be able to stop moving backwards, but will continue to accelarate such that it is now moving forward on the belt going in reverse. It is only a matter of time before the acceleration achieved the velocity required for lift off. If the belt speed increases with the planes speed and no forward motion of the plane takes place...the plane will not fly. Yes, no velocity = no lift. But you have yet to explain the force vectors involved that prevent an increase in velocity (aka, an acceleration). It's really a trivial situation....attached is a force vector diagram. In order for the plane to NOT accelerate, the friction force needs to exceed that of the propulsion force. Since the plane WILL accelerate, then it is just a matter of time until it reaches the necessary velocity. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted November 17, 2006 Share Posted November 17, 2006 Okay, I am changing my position on this. Previous position of course itll take off. Youre all bunch of dunderheads if you dont get that. The motion of the plane through the air is independent of and not correlated to the motion of the belt beneath the plane. Current position no, the plane will not take off. If I read the initial question to state that the conveyor belt is measuring the speed of the plane *RELATIVE TO THE CONVEYOR BELT* and the belt is moving in the opposite direction at the same speed, then the plane will never move from a fixed reference point on the ground next to the conveyor. I apologize to anyone I belittled for seeing this before I did. I dont have time now to go through the whole process that led to my flip flop on this, but Ill post it later today if anyone cares. Quote Link to comment Share on other sites More sharing options...
PhilMays Posted November 17, 2006 Share Posted November 17, 2006 Captains Log: 11/17/2006 1:00PM EST First problem: Apparently it is harder to get a 300 foot x 60 foot belt. I have tried Ace Hardware, Lowe's, and ebay. I've not even tackled how many squirells I will need to move belt. Second problem: wife is not ammused with large backyard project. Third problem: Kids not making eye contact with me. I think it's the crazed wild eyed look and stragly beard. Forth problem: Dog is growling at me when I enter his "space". Fifth problem: The realization that I am a nerd for worrying about crap that doesn't matter. Quote Link to comment Share on other sites More sharing options...
oldenough Posted November 17, 2006 Share Posted November 17, 2006 Phil why would you think you need a 60" x300' belt, after all the plane is not going to move, the maximum you will need is a belt for each wheel the same size as the footprint of the tire. Unless of course you have some doubts???? P,s Please do'nt give up now, surely you can put up with a little discomfort and ridicule to further our knowledge. Please be assured this is not ridicule (snigger, snigger) simply trying to be helpful. Quote Link to comment Share on other sites More sharing options...
PhilMays Posted November 17, 2006 Share Posted November 17, 2006 Phil why would you think you need a 60" x300' belt, after all the plane is not going to move, the maximum you will need is a belt for each wheel the same size as the footprint of the tire. Unless of course you have some doubts???? P,s Please do'nt give up now, surely you can put up with a little discomfort and ridicule to further our knowledge. Please be assured this is not ridicule (snigger, snigger) simply trying to be helpful. Well, that does cut down on the number of squirrels I'll need. Quote Link to comment Share on other sites More sharing options...
oldenough Posted November 17, 2006 Share Posted November 17, 2006 Phil said: Well, that does cut down on the number of squirrels I'll need. LOL, do,nt worry about the family and dog, obviously your sense of humour will pull you through this and you will forever be a hero to them. Quote Link to comment Share on other sites More sharing options...
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