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Posted: 1/26/2012 1:23:21 PM EDT
[#1]
Quoted: Quoted: I'd have to agree with Kieth_J on this one... I have limited understanding of 447's, but running the VW engines in an aircraft is a lot like running a computer on Windows 3.11... Crashtastic. How many times did my mom's V-Dub leave us stranded in a fucking blizzard when the engine died I can't even remember... Wool Blankets, and car emergency kits were normal in my childhood. I'd hate to have such a thing trying to keep me in the air.Quoted: Quoted: Rotax 447? Always have a place to land. Crappy glide ratio and low altitude means you don't have much time to find a suitable landing strip. Plus you will have a helmet fire in trying to figure wind direction+speed. A Hexadyne P60 would be a better fit. Four-stroke boxer twin, geared. Fuel injected, uses regular pump gasoline. 98 pounds with electric starter. Yes, more expensive but the 447 has a 300 hour TBO where the P60 has at least 4 times that. The half VW engines (VW crankcase cut down to make a two cylinder) have been around since the 1970's, weigh around 90 pounds, but the horsepower is only 35 to 40. Cheaper than the Hexadyne, and there is something to be said for simplicity in an aircraft engine. Remember, running an engine at 100% of its output decreases TBO dramatically. This is the issue with 447 and the VW conversions. The VW designs also suffer from direct driven props, meaning plenty of noise at 3400 RPM. Designing a reduction drive is out of the question as the engine is already heavy. One of the more interesting designs of the P60 is common crank with perfectly opposed cylinders. This is done by having a double connecting rod on one cylinder. This makes the crank lighter as the rocking moment is reduced. Remote oil sump also helps with weight and trim issues. You CAN make a VW work. But it doesn't have the bearing area to support a prop, it was made for a flywheel. This is one area that is addressed in some designs. Then there are crank harmonics. Forget about anything other than a wood prop but when to replace? How about ignition? Some use a multiple (wasted spark) system to offer redundancy with dual plug modifications. By the time you are there, you have exceeded the cost of the Hexadyne P60's cost, even with a 1/2 engine. Part 103 only works when you can get the weight down. Can you make a 100 pound airframe? Certainly. Can you make an 80 pound airframe? Unlikely. Also, consider the option of floats, BRS (always a good idea) and the maximum ramp weight. Do you want to have minimal power in a fixed prop? Direct drive? No, you want to swing an efficient prop through the air that will suit your draggy airframe. |
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Posted: 1/26/2012 1:27:54 PM EDT
[#2]
Quoted:
Can it be weaponized? 
Just kidding, kinda, cool project  I know they say there are no stupid questions, but... JK
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Posted: 1/26/2012 3:39:25 PM EDT
[#3]
Quoted:
Quoted:
Quoted:
I'd have to agree with Kieth_J on this one... I have limited understanding of 447's, but running the VW engines in an aircraft is a lot like running a computer on Windows 3.11... Crashtastic. How many times did my mom's V-Dub leave us stranded in a fucking blizzard when the engine died I can't even remember... Wool Blankets, and car emergency kits were normal in my childhood. I'd hate to have such a thing trying to keep me in the air.Quoted:
Quoted:
Rotax 447? Always have a place to land. Crappy glide ratio and low altitude means you don't have much time to find a suitable landing strip. Plus you will have a helmet fire in trying to figure wind direction+speed. A Hexadyne P60 would be a better fit. Four-stroke boxer twin, geared. Fuel injected, uses regular pump gasoline. 98 pounds with electric starter. Yes, more expensive but the 447 has a 300 hour TBO where the P60 has at least 4 times that. The half VW engines (VW crankcase cut down to make a two cylinder) have been around since the 1970's, weigh around 90 pounds, but the horsepower is only 35 to 40. Cheaper than the Hexadyne, and there is something to be said for simplicity in an aircraft engine. Remember, running an engine at 100% of its output decreases TBO dramatically. This is the issue with 447 and the VW conversions. The VW designs also suffer from direct driven props, meaning plenty of noise at 3400 RPM. Designing a reduction drive is out of the question as the engine is already heavy. One of the more interesting designs of the P60 is common crank with perfectly opposed cylinders. This is done by having a double connecting rod on one cylinder. This makes the crank lighter as the rocking moment is reduced. Remote oil sump also helps with weight and trim issues. You CAN make a VW work. But it doesn't have the bearing area to support a prop, it was made for a flywheel. This is one area that is addressed in some designs. Then there are crank harmonics. Forget about anything other than a wood prop but when to replace? How about ignition? Some use a multiple (wasted spark) system to offer redundancy with dual plug modifications. By the time you are there, you have exceeded the cost of the Hexadyne P60's cost, even with a 1/2 engine. Part 103 only works when you can get the weight down. Can you make a 100 pound airframe? Certainly. Can you make an 80 pound airframe? Unlikely. Also, consider the option of floats, BRS (always a good idea) and the maximum ramp weight. Do you want to have minimal power in a fixed prop? Direct drive? No, you want to swing an efficient prop through the air that will suit your draggy airframe. The first rule of propeller design, or selection in this case, is "to keep the propeller as long as possible, as long as possible". The idea is to move large volumes of air, the more the better, since a propeller does not impart particularly high speeds to the air. |
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Posted: 1/26/2012 3:50:17 PM EDT
[#4]
wait....
am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is |
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Posted: 1/26/2012 4:15:10 PM EDT
[#5]
WA-116
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Posted: 1/26/2012 4:20:53 PM EDT
[#6]
Quoted: wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is No. I am using a set of known good plans, and modifying them to suit my needs, and then building it from scratch. Thanks.  |
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Posted: 1/26/2012 4:22:12 PM EDT
[#7]
Oh, so tagged!
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Posted: 1/26/2012 4:23:18 PM EDT
[#8]
I am debating between the Rotax 447, 503-1 and 503-2...I really need to find a solid model of the engines, gearboxes, and electric starts. Contacted Rotax, and they stated they didn't have any models of the airplane engines.
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Posted: 1/26/2012 4:25:37 PM EDT
[#9]
Quoted: wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is Just building. From plans. Plan-built plane. As long as the complete plane is less than 254 pounds dry weight (with some exceptions, like for ballistic parachute or floats), 55 knots at level flight and full power maximum speed, power off stall speed no more than 24 knots, 5 gallons of fuel...plus a host of operation rules, these VEHICLES can be operated without a license. Unless you have considerable UL vehicle experience, designing one from scratch and then flying it is nearly impossible. |
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Posted: 1/26/2012 4:27:35 PM EDT
[#10]
What's a decent used one go for?
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Posted: 1/26/2012 5:10:32 PM EDT
[#11]
Quoted:
What's a decent used one go for? Not sure the words decent and used go together when talking ultra lights...
Aviator |
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Posted: 1/26/2012 5:29:59 PM EDT
[#12]
Quoted:
Quoted:
wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is Just building. From plans. Plan-built plane. As long as the complete plane is less than 254 pounds dry weight (with some exceptions, like for ballistic parachute or floats), 55 knots at level flight and full power maximum speed, power off stall speed no more than 24 knots, 5 gallons of fuel...plus a host of operation rules, these VEHICLES can be operated without a license. Unless you have considerable UL vehicle experience, designing one from scratch and then flying it is nearly impossible. Check the FARs. The 254 pound limit is the entire airplane, minus pilot and fuel. As far as I know, there is no exception for a BRS. I don't know anything about floats. Bottom line: Don't take my word for it. The FARs (and thus the FAA designated inspector) is the final authority. |
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Posted: 1/26/2012 5:43:49 PM EDT
[#13]
Quoted: Quoted: Quoted: wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is Just building. From plans. Plan-built plane. As long as the complete plane is less than 254 pounds dry weight (with some exceptions, like for ballistic parachute or floats), 55 knots at level flight and full power maximum speed, power off stall speed no more than 24 knots, 5 gallons of fuel...plus a host of operation rules, these VEHICLES can be operated without a license. Unless you have considerable UL vehicle experience, designing one from scratch and then flying it is nearly impossible. Check the FARs. The 254 pound limit is the entire airplane, minus pilot and fuel. As far as I know, there is no exception for a BRS. I don't know anything about floats. Bottom line: Don't take my word for it. The FARs (and thus the FAA designated inspector) is the final authority. I have. Many times. 1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation; http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div6&view=text&node=14:2.0.1.3.16.1&idno=14 Straight from United States Government Printing Office, the "publisher" of the Code of Federal Regulations including Federal Aviation Regulations. |
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Posted: 1/26/2012 6:23:48 PM EDT
[#14]
Quoted:
The first rule of propeller design, or selection in this case, is "to keep the propeller as long as possible, as long as possible". The idea is to move large volumes of air, the more the better, since a propeller does not impart particularly high speeds to the air. Use the emgine's (or prop shaft, if using a gear reduction) max RPM to determine what maximum diameter will keep the prop tips in the subsonic range. Then use the aircraft's speed range (0 to 55 knots) to find a pitch that will be efficient at that speed range, not load the engine down too much, and keep the engine from overreving in level flight. Correct? ETA: Or call the prop manufacturer, give them the engine's max rpm and max output and the aircraft's max speed in level flight, and ask what they have that will meet your needs. |
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Posted: 1/26/2012 6:30:00 PM EDT
[#15]
Quoted:
Quoted:
The first rule of propeller design, or selection in this case, is "to keep the propeller as long as possible, as long as possible". The idea is to move large volumes of air, the more the better, since a propeller does not impart particularly high speeds to the air. Use the emgine's (or prop shaft, if using a gear reduction) max RPM to determine what maximum diameter will keep the prop tips in the subsonic range. Then use the aircraft's speed range (0 to 55 knots) to find a pitch that will be efficient at that speed range, not load the engine down too much, and keep the engine from overreving in level flight. Correct? Almost. The prop has to absord all the power the engine can develop, too, and it can't hit anything.
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Posted: 1/26/2012 6:40:02 PM EDT
[#16]
Good luck.
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Posted: 1/26/2012 6:44:54 PM EDT
[#17]
Quoted:
Quoted:
Quoted:
The first rule of propeller design, or selection in this case, is "to keep the propeller as long as possible, as long as possible". The idea is to move large volumes of air, the more the better, since a propeller does not impart particularly high speeds to the air. Use the emgine's (or prop shaft, if using a gear reduction) max RPM to determine what maximum diameter will keep the prop tips in the subsonic range. Then use the aircraft's speed range (0 to 55 knots) to find a pitch that will be efficient at that speed range, not load the engine down too much, and keep the engine from overreving in level flight. Correct? Almost. The prop has to absord all the power the engine can develop, too, and it can't hit anything.
Absorbing all the power was what I meant by keeping the engine from overreving in level flight. At full throttle and max level speed, the prop should put enough of a load on the engine to keep the engine from exceeding it's max rpm. As for not hitting anything, just bump up the nitrogen change in the struts. If that's not enough, put bigger tires on it. 
I saw a Beech Baron that had been converted to a single engine turboprop (removed the engine nacelles from the wings, and replaced the nose baggage compartment with an engine mount and fiberglass cowling), and they apparently hadn't put too much thought into the clearance problem. It hit a dip in the ramp, and the prop being so much farther forward (to get the CG back in it's proper range) meant the prop was on the other side of the dip when the nosewheel was at the bottom of the dip. From what I heard, the pilot said something about possibly suing the airport for the damage their dip did to his prop and engine. |
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Posted: 1/26/2012 8:11:01 PM EDT
[#18]
Likely a dumb question here.
What about using a v-twin motorcycle engine? There was a company called "Hog Air" that did so a while back. Would the motor be too heavy? You should be able to get about 100hp out one. |
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Posted: 1/26/2012 8:59:06 PM EDT
[#19]
Quoted: Likely a dumb question here. What about using a v-twin motorcycle engine? There was a company called "Hog Air" that did so a while back. Would the motor be too heavy? You should be able to get about 100hp out one. The problem is there are strict speed limits on the aircraft - it has to be 60mph max speed to be an ultralight. So, too heavy and too powerful. |
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Posted: 1/27/2012 12:11:39 AM EDT
[#20]
tag
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Posted: 1/27/2012 2:11:36 AM EDT
[#21]
In!
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Posted: 1/27/2012 4:06:50 AM EDT
[#22]
Quoted:
Quoted:
Quoted:
Quoted:
wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is Just building. From plans. Plan-built plane. As long as the complete plane is less than 254 pounds dry weight (with some exceptions, like for ballistic parachute or floats), 55 knots at level flight and full power maximum speed, power off stall speed no more than 24 knots, 5 gallons of fuel...plus a host of operation rules, these VEHICLES can be operated without a license. Unless you have considerable UL vehicle experience, designing one from scratch and then flying it is nearly impossible. Check the FARs. The 254 pound limit is the entire airplane, minus pilot and fuel. As far as I know, there is no exception for a BRS. I don't know anything about floats. Bottom line: Don't take my word for it. The FARs (and thus the FAA designated inspector) is the final authority. I have. Many times. 1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation; http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div6&view=text&node=14:2.0.1.3.16.1&idno=14 Straight from United States Government Printing Office, the "publisher" of the Code of Federal Regulations including Federal Aviation Regulations. Cool. I learned somethnig (happens sometimes). |
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Posted: 1/27/2012 5:09:23 AM EDT
[#23]
Quoted: Quoted: Quoted: Quoted: Quoted: I think it would be incredible to build an airplane just to mess around in. My neighbor has built three now and I've seen him go over the house on nice summer mornings in his last one. I've toyed with the idea of building a DR1 from these guys: http://www.airdromeaeroplanes.com/index.html Realistically, it won't happen. Which is probably a good thing as I've already amassed several bowling balls to drop into a local lake from the air.  Sounds like you're a man in need of a mortar! Yep...mounted in an AIRPLANE! Jeez, think of the possibilities. When firing ordinance from an aircraft, I always prefer that it drop below my aircraft and continue well clear. Unless... You want the dubious honor of being the first pilot to shoot himself down with a mortar! v vAs I recall, that has been done (but with cannon fire), during a test flight of one of Grumman's fighters (F11F, I think?). |
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Posted: 1/27/2012 10:15:11 AM EDT
[#24]
Quoted:
Quoted:
wait.... am I understanding this correctly...you are building designing and building a plane from scratch I do not have the words to describe how cool that is Just building. From plans. Plan-built plane. As long as the complete plane is less than 254 pounds dry weight (with some exceptions, like for ballistic parachute or floats), 55 knots at level flight and full power maximum speed, power off stall speed no more than 24 knots, 5 gallons of fuel...plus a host of operation rules, these VEHICLES can be operated without a license. Unless you have considerable UL vehicle experience, designing one from scratch and then flying it is nearly impossible. Well, flying it twice is nearly impossible. |
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Posted: 1/27/2012 10:23:06 AM EDT
[#25]
Quoted:
Quoted:
Likely a dumb question here. What about using a v-twin motorcycle engine? There was a company called "Hog Air" that did so a while back. Would the motor be too heavy? You should be able to get about 100hp out one. The problem is there are strict speed limits on the aircraft - it has to be 60mph max speed to be an ultralight. So, too heavy and too powerful. Also, a motorcycle engine designed to make 100 HP can do so only briefly, and at fairly high RPM. Most of the time they are putting out a small fraction of that. An airplane engine has to be able to produce it's rated HP for long periods of time. An MC engine might only last an hour. That's why you don't see car engines in airplanes, and why airplane engines cost as much as nice cars. |
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Posted: 1/27/2012 10:24:40 AM EDT
[#26]
Quoted:
Quoted:
Likely a dumb question here. What about using a v-twin motorcycle engine? There was a company called "Hog Air" that did so a while back. Would the motor be too heavy? You should be able to get about 100hp out one. The problem is there are strict speed limits on the aircraft - it has to be 60mph max speed to be an ultralight. So, too heavy and too powerful. Has anyone used any of the modern 450cc dirtbike motors? |
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Posted: 1/27/2012 10:29:26 AM EDT
[#27]
Quoted:
One nice perk is you can completely build this thing in a 2 car garage. I've built four Quad City Challenger II Clipwing Specials,the first one in a two-car garage. Always liked the two place Kolbs but thought they were too slow. Their side by side seating was nice,though. |
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Posted: 1/27/2012 10:44:53 AM EDT
[#28]
Quoted: Likely a dumb question here. What about using a v-twin motorcycle engine? There was a company called "Hog Air" that did so a while back. Would the motor be too heavy? You should be able to get about 100hp out one. Crappy harmonics, for one. Common crank pin engines were at one time, common in aircraft. As in radial engines, but with single crank pin. But these always have an odd number of cylinders due to the 4-stroke process, every other cylinder fires so in two revolutions, each cylinder fires once. Instantaneous torque is in the 200% range, meaning the crank can be much lighter (and shorter) than a similar power engine with shared pin engine. V-twins have horrible vibration which tears the airframe apart, requires a carefully designed mount and as previously stated, would have a short life at a 75% power output for the majority of its life. http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_piston_engines.htm V-twins require considerable external balancing yet still have vibration issues. |
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Posted: 1/27/2012 11:07:45 AM EDT
[#29]
Very cool.
I fly light sport, Avid MKIV aerobat in the garage. 2seats, 560lbs, 6g working load limit, 85 HP Jabiru 4 stroke, tricycle gear, 100 mph cruise. It has 135 hrs on it now, the Jabiru is a 2000 hour maintenance cycle. With the wings folded it will just fit in a 1 car garage sitting on the trailer. Only takes a few minutes to set it up and trailer it, it's a pretty good setup I think. UL is very tempting, there are great deals to be had on low hours LSAs, some people like to build more than they like to fly it seems. |
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Posted: 1/27/2012 11:20:06 AM EDT
[#30]
I do need to find someone who flys ULs down here. I need to take some training in one for sure...never been in one, hell, I might hate it.
I also plan on taking several GA training flights to learn airport operations, patterns, radios, etc. I do plan on having a handheld aviation radio in the bird.
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Posted: 1/27/2012 11:37:11 AM EDT
[#31]
Well, Wiki is coming online. This is for anyone who already has purchased plans and has the capability to work with SolidWorks 2011 files.
Eventually if we get it far enough, I may open up large sections to the public (where there is no CAD files to protect the owners IP.) IM me if you want access. |
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Posted: 1/27/2012 1:51:57 PM EDT
[#32]
Never messed with solidworks, but the image of that model you posted would be pretty easy to do in rhino.
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Posted: 1/27/2012 2:12:57 PM EDT
[#33]
Quoted: Never messed with solidworks, but the image of that model you posted would be pretty easy to do in rhino. Solidworks is more a solid modeling program with some CAM capacity. Useful for design from ground up and virtual parts assembly. Also has automatic drawing output for parts, assemblies and bills of material. |
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Posted: 1/27/2012 2:20:23 PM EDT
[#34]
Rhino has a blueprint feature. Not sure about materials list, tho.
Rhino is more of a surface modeler, tho you can certainly use it for manufacturing. Integrated CAM for exactly that. |
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Posted: 1/27/2012 2:22:19 PM EDT
[#35]
OP, I just sent you a reply. I have SWX 2011 Premium with Simulation. So we should be good to go.
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Posted: 1/27/2012 2:22:38 PM EDT
[#36]
Tag. Hopefully you dont die.
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Posted: 1/27/2012 2:26:04 PM EDT
[#37]
Cool.
I think you should post some pics of your sim that you built to show people in this thread what you're capable of. |
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Posted: 1/27/2012 2:55:31 PM EDT
[#38]
LSA Avid sitting in the shop. Looked at UL but for a little more $$ I went that route. Fun toy with the heavy hauler.
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Posted: 1/29/2012 10:47:29 AM EDT
[#39]
Well, still CADDing. Completed the Main Landing Gear assembly (sans actual wheels) and its showing a hair over 60 pounds....several pounds more than the main fuselage. I gotta figure out a redesign to cut that in half, and still maintain rough field TO/LDG capability. Hrm.
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Posted: 1/29/2012 11:13:22 AM EDT
[#40]
Stick with the original design for the landing gear. 60 pounds is a killer.
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Posted: 1/29/2012 11:51:34 AM EDT
[#41]
Quoted:
Stick with the original design for the landing gear. 60 pounds is a killer. The original design is 60 pounds according to my CAD model. 
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Posted: 1/29/2012 7:31:49 PM EDT
[#42]
Double check the density in your program. The 1.125X0.058X45.125 axle tube weighs about 0.88 pounds.
I started to calculate the weight, but there are too many missing dimensions in the prints and I'm not going to lay them out. You're smart to redraw the assembly as that will uncover the interferences and missing information in the manual and sketches. |
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Posted: 1/29/2012 7:46:53 PM EDT
[#43]
Quoted: Double check the density in your program. The 1.125X0.058X45.125 axle tube weighs about 0.88 pounds. I started to calculate the weight, but there are too many missing dimensions in the prints and I'm not going to lay them out. You're smart to redraw the assembly as that will uncover the interferences and missing information in the manual and sketches. I didn't believe it either, so I did. 62 pounds for the assembly (including rear struts and hardware connecting to main fuselage.) Weight on the check item is 0.85 pounds. If I build it in CAD, I don't have to decipher plans anymore - I already know how it works. Honestly, I may just be spoiled having learned how to draft in the defense industry, but these are some of the worst drawings I've ever seen. |
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Posted: 1/29/2012 7:50:03 PM EDT
[#44]
Quoted:
Tag for 1/4 mile high club. |
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Posted: 1/29/2012 7:52:42 PM EDT
[#45]
0.0975 pounds per cubic inch. Meaning a 60 pound part has volume of 615 cubic inches. Your math is wrong. If you budget 125 pounds for the power plant, you have 129 pounds for airframe, controls, covering and landing gear. 60 pound landing gear and now you are down to 69 pounds for airframe, controls, covering and seat.
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Posted: 1/29/2012 8:00:40 PM EDT
[#46]
If you want, share the models that you have on the Wiki and I'll confirm the density.
Also, I've never used a Wiki page before. Maybe the models are already there, but I couldn't find them. I'm still trying to figure it all out though. |
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Posted: 1/29/2012 8:06:23 PM EDT
[#47]
Quoted:
Quoted:
Double check the density in your program. The 1.125X0.058X45.125 axle tube weighs about 0.88 pounds. I started to calculate the weight, but there are too many missing dimensions in the prints and I'm not going to lay them out. You're smart to redraw the assembly as that will uncover the interferences and missing information in the manual and sketches. I didn't believe it either, so I did. 62 pounds for the assembly (including rear struts and hardware connecting to main fuselage.) Weight on the check item is 0.85 pounds. If I build it in CAD, I don't have to decipher plans anymore - I already know how it works. Honestly, I may just be spoiled having learned how to draft in the defense industry, but these are some of the worst drawings I've ever seen. You should see what used to pass for scratch built plans. The builder had to know how to build an airplane, the plans were just barely guidelines. I have a set of original Cassutt plans that are the most humorous. The flat patterns for the cowling will fit on an 8 1/2 X 11 inch sheet of paper. Then there are the original Windwagon plans. They aren't hilarious, they're just plain sad. A universal problem with plans in the homebuilt airplane world is the lack of checking of the drawings before selling, and then failure to update or correct the drawings as the builders uncover the problems. This is one reason it's impertive to belong to a builder's group. Allow about 0.102 to 0.103 pounds per cubic inch for your aluminum parts in order to incorporate allowance for a [u]light[/i] coat of primer and paint. |
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Posted: 1/29/2012 8:07:28 PM EDT
[#48]
It really isn't passing the sniff test to me either, but I'm not seeing any obvious failure, and I've used it very accurately in the past to calculate weights.
   The seat shown is the third picture is just a placeholder. (I haven't decided on a real seat yet, or a harness.) The seat itself is assigned a zero mass with the brackets having normal properties of the 6061-T6. Looked on GrabCAD and 3dcontentcentral for a normal Walmart 5 gallon gas can to no avail, so I'll need to go buy one and model that to design my fuel system around. (The gas can goes on the little bracket to the rear of the seat.) |
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Posted: 1/29/2012 8:11:14 PM EDT
[#49]
You could estimate the weight for a plastic fuel can by using 0.04 pounds per cubic inch density. 1 US gallon is 231 cubic inches. Use 6 pounds per gallon for the weight of gasoline.
Edited to fix the density; that was wearing on me this morning, and sure enough I screwed it up the first time. |
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Posted: 1/29/2012 8:11:51 PM EDT
[#50]
Quoted:
It really isn't passing the sniff test to me either, but I'm not seeing any obvious failure, and I've used it very accurately in the past to calculate weights. http://i263.photobucket.com/albums/ii135/jrsteensen/A-Plane%20Build/f3516562.png http://i263.photobucket.com/albums/ii135/jrsteensen/A-Plane%20Build/8d2f6928.png http://i263.photobucket.com/albums/ii135/jrsteensen/A-Plane%20Build/dc33b8e1.png The seat shown is the third picture is just a placeholder. (I haven't decided on a real seat yet, or a harness.) The seat itself is assigned a zero mass with the brackets having normal properties of the 6061-T6. Looked on GrabCAD and 3dcontentcentral for a normal Walmart 5 gallon gas can to no avail, so I'll need to go buy one and model that to design my fuel system around. (The gas can goes on the little bracket to the rear of the seat.) Looks like your volume is jacked up. 1530 in³ seems WAY too high. |
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