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Old Apr 25, 2014, 09:39 AM
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Going to build David Ramey's Boeing 727-100 - few questions

Good afternoon fellow R/C fliers,
I have had the plans for David Ramsey's Boeing 727 for over 10 years now but was put off as to making the ribs and formers for the construction. A week ago I was browsing the web when I found LDS laser design in the U.S do a short kit for the 727- I ordered it in a heart beat !
The original design uses 2 x GWS 50mm 3 blade with brushed motors, I have the GWS fans but I have 2 x 12mm Hyperion brushless can motors in them now and I will be using 2 x 12A ESC's. Just a question, what lipo do I use, 3S or 2S ?
This will be my 2nd traditional build aircraft I have built my 1st was Pat Tritles Douglas DC6,I flew her a month ago and all went well but the wind picked so I landed early. I have been looking at David Ramsey's building thread and have just finished building the building jig for the fuselage-Photo of my DC6 and the B727 building jig. Any advice or tips out there will be greatly appreciated ! Oh yes, a BIG thank you to Bob of LDS laser design U.S for posting my short kit to the U.K.
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Old Apr 25, 2014, 10:20 AM
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I have the GWS fans but I have 2 x 12mm Hyperion brushless can motors in them now and I will be using 2 x 12A ESC's. Just a question, what lipo do I use, 3S or 2S ?
That depends on the Kv of your motors.
You can use various online EDF calculators to plug in your numbers and check the thrust and current draw.
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Old Apr 25, 2014, 11:35 AM
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That depends on the Kv of your motors.
You can use various online EDF calculators to plug in your numbers and check the thrust and current draw.
Thanks Sergey,
I have had a look at some performance charts, I put the Hyperion motors in many years ago when I had less grey hair lol ! I will find my paper work for the motors to check the KV which I have forgotten.
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Old Apr 25, 2014, 11:51 AM
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Thanks Sergey,
I have had a look at some performance charts, I put the Hyperion motors in many years ago when I had less grey hair lol ! I will find my paper work for the motors to check the KV which I have forgotten.
I have checked the motors they are 12mm can Hyperion Y12L-5300 KV motors.
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Old Apr 25, 2014, 12:22 PM
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I have checked the motors they are 12mm can Hyperion Y12L-5300 KV motors.
I suspect you should be fine on 3s, but make a test with a wattmeter to make sure you're not pulling too much a current.
For comparison, I'm pulling about 25A on a 7-blade 55mm fan with a 20mm 4100Kv motor.
So your motor - a little hard to say. The fan is smaller, the Kv is higher, but the blade count lower. It's a toss up - an actual measurement is required.
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Old May 05, 2014, 02:22 PM
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I suspect you should be fine on 3s, but make a test with a wattmeter to make sure you're not pulling too much a current.
For comparison, I'm pulling about 25A on a 7-blade 55mm fan with a 20mm 4100Kv motor.
So your motor - a little hard to say. The fan is smaller, the Kv is higher, but the blade count lower. It's a toss up - an actual measurement is required.
Hi Sergey,
Thanks for your input, I've got my short kit for the 727 arriving tomorrow from the U.S. I found this performance chart for 5300 KV motor - of course I'm using two 50mm 3 blade unit s
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Old May 05, 2014, 02:51 PM
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Hi Sergey,
Thanks for your input, I've got my short kit for the 727 arriving tomorrow from the U.S. I found this performance chart for 5300 KV motor - of course I'm using two 50mm 3 blade unit s
Looks like you would be OK on 3s.
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Old May 05, 2014, 03:16 PM
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Old May 05, 2014, 04:31 PM
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Thanks guys, I can't wait to start my build ! Have been reading the instructions to get my head round the construction process. Will use my new watt meter to check my set up but it's good to get advice from more knowledgeable people.
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Old May 05, 2014, 08:32 PM
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Enough of the chatter, let's get building..shall we. Can't wait see how this aircrafts takes shape. ..
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Old May 24, 2014, 12:20 PM
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Just started my build of David Ramsey's Boeing 727- progress so far. So glad LDS laser design produced a short kit !
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Old May 25, 2014, 08:21 AM
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So glad LDS laser design produced a short kit !
Looks great. I'm going to enjoy watching your progress.

I'm curious; did the laser cut formers follow the grain (2 piece per half) pattern shown on the plans, or were they done in half sections?

Thanks.
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Old May 25, 2014, 01:03 PM
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Looks great. I'm going to enjoy watching your progress.

I'm curious; did the laser cut formers follow the grain (2 piece per half) pattern shown on the plans, or were they done in half sections?

Thanks.
Good afternoon David-Master of the Boeing 727 !
The laser cut of the formers and grain direction are as your plans, two piece per half, I have just started applying the stringers to the formers. I have also just paided the customs on two GWS 50mm EDF's with brushless motors from Hong Kong already assembled., I will be using a 3S 11.1V lipo to power my jet. No doubt I will have some questions for you David as I proceed with my build. I'm coming to the U.S this Thursday (Florida) for a 10 day holiday-I have arranged to go up in a AT6 Texan for an hour when I'm over- looking forward to it ! Consequently my build will have to wait till I back from my holiday. Thanks for producing the plans for the Boeing 727 David and also the article on the build, I have read it loads of time now to get my head round the building process.
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Old May 25, 2014, 02:18 PM
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David, retail this is a truly awesome 727 build!

727 Forever!
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Old May 26, 2014, 10:07 AM
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Good afternoon David-Master (?) of the Boeing 727 !
The laser cut of the formers and grain direction are as your plans, two piece per half, I have just started applying the stringers to the formers.
Thanks for the response and the very kind reference. Holy cow; an hour in an
AT6 ... what a hoot!
Have a great and safe holiday.
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