If I tell you that I (as a green engineer) have helped lofting the front end of the SAAC23 - including the racy windshield - I probably give away my age. One to one on blue covered steel foil. The "drawingboard was as large as one whole wall of the drawing office.
Danilo and Tomtom, why do you actually want to know which profile I will use? I can not quite understand why such a fuss is made about that. For a plane of the envisaged size (and a bit larger), weight and speed range there is not really much choice. Oh yes, there are literally hundreds of profiles available, but in the end they all can not demonstrate better characteristics than the Clark Y. In fact any flat bottomed ~11.5% thick as a base will do. Same here - the root profile is a Clark Y "derivat". The rest I will describe in the following blog posts.
Mark,that EDF is probably perfectly suitable - I don't know it. If you can test run it and do some measurements you could find out how efficient it is. The lower end at about 200W - 250W is importent for long range and endurance. Only for the start you will need full power and about 1 - 1.3 kgf (2.2 - 2.7 lb) thrust.
I found this 580 watt, 74mm Ducted fan with brushless motor on DealExtreme for $27 could be a decent unit for this project.. Looks like Wakera makes it, OK quality..runs on 3 lipo cells.
Wendi,
your layouts are excellent, I like it when you are asked what program (3d) you used : )
I was lucky enough to learn how to Loft in school, and that has allowed me to use any drawing tool, digital or "analog" to create plans and renderings. My current favorite is sketchbook pro, which is basically a digital sketchpad you sketch lines into, very few guides or tools. Hard to do draftings but love to ideate with it.
Your craftsmanship looks great from here.
Looking forward to more info on your design as the build progresses.
I can reduce the pictures further in ACDSee but then the quality suffers. I thought that there might be some special function here in the DIY Drone forum to reduce attachments for the sake of a better over-view, and the viewer could look at them full size when she/he so wishes (like in RCG).
Anyway I will try to answer the questions and then continue with my build blog.
Hooks, I would like to take you up on that offer. Problem is that I do my "drawings" in Corel, which is a nice vector program, but I don't know whether you can import that format. I can transport Corel files into dxf format, which may help.
I’m using Corel for many years now, before proper CAD drawing programs became common goods and affordable. It’s very useful and I know my way around it. Somehow I missed the train to 3D and I’m not trying to run after it now.
For the doubters of EDFs I can only say that I do EDFs since about 12 years and ICDFs for even longer. I do know there limitations quite well. But a prop also has it’s drawbacks. Principally one can get better efficiencies with larger air mass and smaller delta v, which means larger diameter of prop or fan, but one also has to take into account that we are really dealing here with relative small power quantities and there the advantages of the larger air mass becomes less important. Total efficiencies are only in the 40-50% region anyway. But I will show you that even a small plane like my Tern can stay aloft for about 30 to 40 minutes on EDF power without conversion into a battery carrier.
The materials and tools I use are easy to get practically anywhere, as long as one does not insist on a particular brand. I use mainly polystyrene foam, but I will also consider the use of balsa as an equivalent substitute. You will find all this info in the blog posts to follow.
Comments
W.
If I tell you that I (as a green engineer) have helped lofting the front end of the SAAC23 - including the racy windshield - I probably give away my age. One to one on blue covered steel foil. The "drawingboard was as large as one whole wall of the drawing office.
Danilo and Tomtom, why do you actually want to know which profile I will use? I can not quite understand why such a fuss is made about that. For a plane of the envisaged size (and a bit larger), weight and speed range there is not really much choice. Oh yes, there are literally hundreds of profiles available, but in the end they all can not demonstrate better characteristics than the Clark Y. In fact any flat bottomed ~11.5% thick as a base will do. Same here - the root profile is a Clark Y "derivat". The rest I will describe in the following blog posts.
Mark,that EDF is probably perfectly suitable - I don't know it. If you can test run it and do some measurements you could find out how efficient it is. The lower end at about 200W - 250W is importent for long range and endurance. Only for the start you will need full power and about 1 - 1.3 kgf (2.2 - 2.7 lb) thrust.
http://www.dealextreme.com/details.dx/sku.15230.
I ordered $20 stuff from them with free shipping from China, If /when parts arrives I will report back...
They have several items for RC at very low cost...
What profile are you using in this wing?!
Regards.
your layouts are excellent, I like it when you are asked what program (3d) you used : )
I was lucky enough to learn how to Loft in school, and that has allowed me to use any drawing tool, digital or "analog" to create plans and renderings. My current favorite is sketchbook pro, which is basically a digital sketchpad you sketch lines into, very few guides or tools. Hard to do draftings but love to ideate with it.
Your craftsmanship looks great from here.
Looking forward to more info on your design as the build progresses.
I can reduce the pictures further in ACDSee but then the quality suffers. I thought that there might be some special function here in the DIY Drone forum to reduce attachments for the sake of a better over-view, and the viewer could look at them full size when she/he so wishes (like in RCG).
Anyway I will try to answer the questions and then continue with my build blog.
Hooks, I would like to take you up on that offer. Problem is that I do my "drawings" in Corel, which is a nice vector program, but I don't know whether you can import that format. I can transport Corel files into dxf format, which may help.
I’m using Corel for many years now, before proper CAD drawing programs became common goods and affordable. It’s very useful and I know my way around it. Somehow I missed the train to 3D and I’m not trying to run after it now.
For the doubters of EDFs I can only say that I do EDFs since about 12 years and ICDFs for even longer. I do know there limitations quite well. But a prop also has it’s drawbacks. Principally one can get better efficiencies with larger air mass and smaller delta v, which means larger diameter of prop or fan, but one also has to take into account that we are really dealing here with relative small power quantities and there the advantages of the larger air mass becomes less important. Total efficiencies are only in the 40-50% region anyway. But I will show you that even a small plane like my Tern can stay aloft for about 30 to 40 minutes on EDF power without conversion into a battery carrier.
The materials and tools I use are easy to get practically anywhere, as long as one does not insist on a particular brand. I use mainly polystyrene foam, but I will also consider the use of balsa as an equivalent substitute. You will find all this info in the blog posts to follow.
All the best (wishes)
W.
Use FastStone Capture 6.5, Great free userfriendly software.
I use it all the time.
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