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Oct 03, 2016, 12:59 AM
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Build Log

McGovern Vulture for CAP 2017


Here goes with my first R/C build, Don McGovern's 80" Vulture sailplane from 1963. I was looking for a gentle entry into R/C and this nicely proportioned power-assisted glider seemed to fit the bill.

While I have an older Enya 09 that would suit the Vulture quite well, I am planning to go electric (also a first for me) for reasons of less mess and fuss and easier power control (I think!).

I am deliberating on whether to put the motor in a pod or in the nose. Harry D and Sundancer have given me some good thoughts on that. I think the best approach is for me to go ahead and buy a suitable motor (thanks George for guidance) and then see how I can nicely cowl this, either in the nose or in a pod, before I start building the fuse.

R/C will be a Futaba 4YF-FM set that I have had sitting here for awhile, waiting for a home. Control will be on motor and rudder and possibly limited elevator (as a precaution if the Vulture ever shows a reluctance to come down).

Plans were printed off today and have come in a fraction under scale but not enough to worry about or justify re-printing.

Now just let me get that motor sorted, and we will be under way.
Last edited by RobtP; May 09, 2017 at 07:01 PM. Reason: Terminology!
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Oct 03, 2016, 01:50 AM
I like real wooden aeroplanes!
Sundancer's Avatar
Going to be interesting Bob.

Just two points. I would recommend that you do fit an elevator from the outset, even if you don't use it much at first it will be good to have it available even if only as a trim option.

Secondly terminology - electrics are not engines, they are motors!
Oct 03, 2016, 06:25 AM
So I'M meant to be in control?
Colonel Blink's Avatar
All aboard....!!!
Oct 03, 2016, 06:32 AM
I like real wooden aeroplanes!
Sundancer's Avatar
Judging by the wonderful job you did on the KR56, your building skills are well up to this, which is the main hurdle. As it is to be your first radio model and your first venture into the wonderful world of modern electric power, no doubt you will have plenty of questions - just ask and there are plenty of people on here who will be only too happy to offer help and advice.
Oct 03, 2016, 07:32 AM
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Nice model. I like the constant cord wing.
John
Oct 03, 2016, 02:42 PM
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Quote:
Originally Posted by Sundancer
I would recommend that you do fit an elevator from the outset
Will do, thanks George.

Quote:
Originally Posted by Sundancer
no doubt you will have plenty of questions - just ask and there are plenty of people on here who will be only too happy to offer help and advice.
Thanks, I'm sure I will, and no doubt a few more terminology blunders (I only found out what ESC stood for yesterday)

Quote:
Originally Posted by JohnAV8R
Nice model. I like the constant cord wing.
John
Thanks John. And no compound curve tip sections to cover
Oct 04, 2016, 05:47 PM
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The motor...


Much as I like the option of putting the motor in the nose, I have decided to stay with the nose pod concept but just change the pylon shape- a little more curvy and built up to enclose the motor wiring. The reasoning is that I want to preserve the Vulture's distinctive nose shape, which I think gives the design some of its character (having been looking at photos of turkey vultures, I think I can see where that comes from ).

Motor choice: amongst a sea of motors and technical language I don't fully understand, I'm wondering if an E-flight Park 370 1360Kv might fit the bill? http://www.e-fliterc.com/Products/De...rodID=EFLM1205

George, this seems close to what you suggested, although wattage is a little higher.

Pod height shown on the plan will allow an 8" prop.

Am I on the right track? Happy to take advice as this is all new to me.

Apart from the motor pylon shape I'm not planning any changes to the plans. Checking over my 1/4" sticks now and about to start on the fuse....
Oct 05, 2016, 03:06 AM
I like real wooden aeroplanes!
Sundancer's Avatar
Given that the original flew with a powerful .049 to an .09 the motor you list should do the job, you would probably want to run the 8 x 3.8 prop from a 3S lipo which should give somewhere around 120 - 130 watts. I don't know what the original weighed, but looking at the structure I would expect a version with modern radio and electrics to come in around 30 to 40 ounces at most, so 120 watts should give a very decent climb without being too wild.
Oct 06, 2016, 06:12 AM
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Thanks George, and also thanks to Alex VK2KR for PM's and for running performance calcs on motor and Vulture. The calcs confirmed the E-flight Park 370 would do a decent job as you say George but would be at full stretch on amperage so have decided to go with a slightly more powerful (and cheaper) option suggested by Alex, which is a Turnigy Park 450, that will have similar climb performance but at lower amperage.

I will order motor, ESC and lipos today.

This has been a very interesting learning exercise for me and nice to have the motor for the Vulture sorted, I can now concentrate on the build. Nothing worth photographing yet, but should be soon.
Oct 06, 2016, 06:23 AM
So I'M meant to be in control?
Colonel Blink's Avatar
If this is a grandma and eggs situation, please ignore it; but if this is the first time you've used lipos....

You will need a lipo specific charger - even a NiMH delta peak charger won't do it and will actually give a fire risk. There are also some precautions it would be wise to take with handling and storage, but we can all go through these with you as and when.
Oct 06, 2016, 03:26 PM
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Yes first time using lipos. I have been recommended a suitable charger but hadn't given thought to handling and storage. I know shippers (air) have issues with them. A timely caution, thanks Colonel.
Oct 07, 2016, 03:18 AM
I like real wooden aeroplanes!
Sundancer's Avatar
The Colonel is absolutely right to point out the specific care required with lipos Bob; fires have been caused by them. However, there is no need to get too paranoid, and if the guidelines are followed they are perfectly safe. 99% of lipo "incidents" are caused by either charging at the wrong settings, short circuiting, failure to spot crash damage or worn wiring or something similar. Common sense precautions are:

Have a charger which allows charging batteries to "storage" voltage.
Never charge batteries IN the model
Check and double check charger settings when connecting
Do not leave charging batteries unattended.
Store batteries in a fire retardant container away from flammable items.

Given just normal sensible care they are perfectly safe., I have had no issues in twenty years of using them. Indeed, the only battery fire I have ever had was caused by a 4.8 volt nicad pack in a slope soarer when I was too slow getting to a crashed model!
Oct 07, 2016, 05:10 AM
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Thanks for the guidance George. I have taken on board and will do my best to be safe.
Oct 07, 2016, 06:27 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Yup - like George said: no need to be paranoid, just sensible. I would suggest that other than the specific charger, if you haven't got something like a cash box already, a quick trip to your friendly neighbourhood Army surplus stores for an ammo box for storage and / or charging is a good idea.
Oct 07, 2016, 02:27 PM
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I had been wondering what might be suitable. Thanks for the suggestion Colonel, I'll check them out.


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