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Boeing 727 build

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Old 12-21-2018, 09:45 PM
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Default Boeing 727 build

Hello I have not posted in a long time. I am currently building a 62 inch wing span b-727. I reduced the planes from a 100 inch model. The original planes call for two 90mm edf's. I am seeking help on what edf's I should plan on using. I want to keep the no 1 & 3 engines as close to scale as possible. I know weight and balance is of great concern. I will need advice on thrust requirements and battery size. The original planes do not call for landing gear but I plan to put retracks on it.. Also the original plans call for tissue or silk covering, I plan to balsa the wing and Fuselage.

I have cut out all the fuselage formers and am close to assembling the fuselage. I plan to do a building blog as soon as I figure out how to upload pictures. I am a retired airline pilot with over 9000 hours as captain on this aircraft and an experienced R/C modeler for over 55 years.

Thanks for your advice and input.
John Castronover

Last edited by jfcgnv; 12-21-2018 at 09:48 PM. Reason: spelling
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Old 12-22-2018, 08:16 AM
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I will be interested in seeing your pictures. A 100 in tissue covered design, sounds like a lot of structual change will be required for retracts and fans.
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Old 12-22-2018, 10:46 PM
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Originally Posted by jfcgnv View Post
Hello I have not posted in a long time. I am currently building a 62 inch wing span b-727. I reduced the planes from a 100 inch model. The original planes call for two 90mm edf's. I am seeking help on what edf's I should plan on using. I want to keep the no 1 & 3 engines as close to scale as possible. I know weight and balance is of great concern. I will need advice on thrust requirements and battery size. The original planes do not call for landing gear but I plan to put retracks on it.. Also the original plans call for tissue or silk covering, I plan to balsa the wing and Fuselage.

I have cut out all the fuselage formers and am close to assembling the fuselage. I plan to do a building blog as soon as I figure out how to upload pictures. I am a retired airline pilot with over 9000 hours as captain on this aircraft and an experienced R/C modeler for over 55 years.

Thanks for your advice and input.
John Castronover
The weight and balance shouldn't be any issue, for such a small w/span, you should be able to build it very light, 70 or 80mm, on 4-5 or 6S power set up might do the job easily. Balance is the least problem, you got the whole fuse length to place lipos for correct CofG. Plenty of retracts avail. on HK if you fly off the hard surface, grass is another story for the small scalish wheels.
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Old 12-23-2018, 04:49 AM
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Thanks Joseph, You are the second person top recommend 70mm fan units. I was hoping to get away with 50 or 60mm units as this would keep the engine nacelles close to scale in size. Do you think this is possible? What about three 64mm engines? Is there a high performance 64mm set available? Is there a formula for thrust to weight for EDF's. I have flown prop electrics and use the formula of 150 wats per pound as a guide for sport flying. Thanks for the input.
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Old 12-23-2018, 07:22 AM
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Originally Posted by jfcgnv View Post
Hello I have not posted in a long time. I am currently building a 62 inch wing span b-727. I reduced the planes from a 100 inch model. The original planes call for two 90mm edf's. I am seeking help on what edf's I should plan on using. I want to keep the no 1 & 3 engines as close to scale as possible. I know weight and balance is of great concern. I will need advice on thrust requirements and battery size. The original planes do not call for landing gear but I plan to put retracks on it.. Also the original plans call for tissue or silk covering, I plan to balsa the wing and Fuselage.

I have cut out all the fuselage formers and am close to assembling the fuselage. I plan to do a building blog as soon as I figure out how to upload pictures. I am a retired airline pilot with over 9000 hours as captain on this aircraft and an experienced R/C modeler for over 55 years.

Thanks for your advice and input.
John Castronover
Hey John!

I also have a type in the 100. I’m building a turbine version with an 81” ws. The design and plans, which are kind of non-existent are in German. I bought the fiberglass plugs of the nose and tail, along with the retracts from Germany. The center section is of hollowed foam to make the fuse, balsa sheeted for a total length of 120” for the 200. The guy was sick that used to cut the wings, so cutting my own, then sheeted. There’s now an ARF out for the turbine version, there wasn’t one when I bought the short kit. With electric you aren’t too concerned about an engine loss. With turbine, they have only figured out how to have two engines operate together in the last couple years. The biggest issue was one engine would read the rpm’s of the other engine and causing it to shut down. So, long story short, the turbine version is a single one in the center. Keeps cost down and the KISS theory. Plus, when the kit was designed, small enough turbines weren’t available for #1-#3. Expected weight will be about 25-30#, and will be using around a 20# thrust engine. As you are aware with full scale thrust to weight is approximately 1:3. And you know how that is on a hot day. With models, the closer that you are to 1:1, the better. I wouldn’t go any less 1:2, or 50% of GTW. Also take in consideration of your flying field whether it is a grass or paved runway.
If you decide to go with one in the center, I have a BVM VioFan 10s that I bought from an estate sale. It’s new, but was mounted in a BVM F86 that wasn’t finished. I have tested it, and it works as described.

Boeing 727 ,Maßstab 1/16 - GRUMANIA JETS

Electric Power
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Old 12-23-2018, 06:04 PM
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Originally Posted by jfcgnv View Post
Thanks Joseph, You are the second person top recommend 70mm fan units. I was hoping to get away with 50 or 60mm units as this would keep the engine nacelles close to scale in size. Do you think this is possible? What about three 64mm engines? Is there a high performance 64mm set available? Is there a formula for thrust to weight for EDF's. I have flown prop electrics and use the formula of 150 wats per pound as a guide for sport flying. Thanks for the input.
Marry Xmas, You could always go for three 64mm units on 4S, you should get enough power if you build it light but complexity of #2 duct is the hassle I rather be with out. Regarding the thrust, with EDFs the more the better in my home, but 50/50 is good enough for a scale airliner on the nice calm day.
I used to fly two similar size "777s" foamies on 64mm/3S fans but it was a floater. tho very scale lookalike.
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Old 12-31-2018, 06:51 AM
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OK, I need help. I have taken several pictures of my 727 build and progress. Now how do I up load them to this thread. They are successfully transferred from my camera to a file on my computer but for the life of me I don't and can't get them transferred to this thread. Also how do I edit my first thread. the original plans call for a 90 inch wingspan not a 100 as posted. the reduction still will be a 60 inch wingspan
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Old 12-31-2018, 10:09 AM
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Hey John!

Reply to your forum. It opens the area to type and reply. Above this area are the tools to add different things. Click on the paper clip. It will open the next page to select pictures from your device or to take pictures.
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Old 12-31-2018, 12:47 PM
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Originally Posted by jfcgnv View Post
Thanks Joseph, You are the second person top recommend 70mm fan units. I was hoping to get away with 50 or 60mm units as this would keep the engine nacelles close to scale in size. Do you think this is possible? What about three 64mm engines? Is there a high performance 64mm set available? Is there a formula for thrust to weight for EDF's. I have flown prop electrics and use the formula of 150 wats per pound as a guide for sport flying. Thanks for the input.
Twin Great Planes HyperFlow 370 EDFs (56mm) will put out a little over 3 lbs of combined thrust with the Ammo 3790kv motors on a single 4s 4400 mAh battery (4 minutes of airtime). You would have to limit your AUW to 5 1/2 lbs though, tough to do with a 60" wingspan. At 6 lbs it truly would be a Lead Sled...

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Old 12-31-2018, 04:22 PM
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I tried your advice and my computer is telling me my pictures are in an un authorized file or format. I am so frustrated. I can open them on my computer so I know they are there and work. I took the pictures on my I phone and sent them to my e mail on my computer.
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Old 12-31-2018, 04:51 PM
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Yeah, I understand computer frustrations. I to have an iPhone and have found your exact problem. It does work if you upload them from your iPhone to RCU. I just uploaded pictures to Market ads with no issues. Try from your phone.

When responding, there’s a “Current Attachments” under the response box. Wait until 3 selection boxes appear. Use the link that says “My Device “, this will allow you to choose from the pictures on your phone. Do not use “My Album “, it is for pictures that are already uploaded to RCU.
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Old 12-31-2018, 11:45 PM
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Originally Posted by jfcgnv View Post
I tried your advice and my computer is telling me my pictures are in an un authorized file or format. I am so frustrated. I can open them on my computer so I know they are there and work. I took the pictures on my I phone and sent them to my e mail on my computer.
Mate, get some young school kids, tell them you used to fly "727" and they'll be more than happy to help you with computer.
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Old 01-09-2019, 10:24 AM
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test upload or post
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Old 01-09-2019, 10:25 AM
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here are some trial photos
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Old 01-13-2019, 08:34 AM
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Last edited by jfcgnv; 01-13-2019 at 08:38 AM. Reason: adding text
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Old 01-13-2019, 08:40 AM
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More pictures to follow. Sorry about the size but at least they uploaded.
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Old 01-13-2019, 08:43 AM
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Old 01-13-2019, 08:49 AM
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Old 01-13-2019, 11:24 PM
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Nice project, that should keep you out of mischief for a while, Cheers.
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