RC India

RC Models => Kites, Trains, Free Flight and All Others => Topic started by: K K Iyer on June 24, 2018, 08:25:26 PM



Title: 15” Druine Turbulent build
Post by: K K Iyer on June 24, 2018, 08:25:26 PM
I realise that not many are interested in this kind of stuff.
But a few might be...

On RCGroups, a veteran champion, Bruce Matthews, is running a ‘Rubber Design Build Off’ for models designed over 50 years ago. There are 37 entries from around the world (2-3 withdrew).
There are no prizes. Just the appreciation of similar enthusiasts.
I joined in just to be in the company of some real experts, and to hear their comments suggestions on my build.

Decided to build a 15” span Druine Turbulent from Walt Mooney’s 1964 plans on outerzone.co.uk
Thinking that it would be comparatively simple.

Well, all I can say is, it’s harder than it looks!

To start with, you need 1/16” sq balsa strips.
Doubt if anyone has a stock of these. Neither did I.

So the strips have to be cut from 1/16 sheet.
To do that accurately, a proper stripper is needed (like Master Airscrew)
Or at least a homemade one like the one I made some 30-40 years ago.
Since I didn’t have the first, and couldn’t find the second,
Had to cut strips by eye.

Then of course the width differs, and one ends up with two fuselage sides that don’t match...

Discard and start afresh.
Now the sizes match, but the stiffness doesn’t, resulting in a banana shaped fuselage...


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 24, 2018, 08:59:59 PM
For some reason, pics not loading
Let me try one at a time.

First pair of fuselage sides discarded...


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 24, 2018, 09:05:49 PM
Second set makes the fuselage banana shaped.
Tried to cure by inserting rectangular plate...


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 24, 2018, 09:25:01 PM
Gradually getting better


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 24, 2018, 09:46:33 PM
Current status tonight


Title: Re: 15” Druine Turbulent build
Post by: sanjayrai55 on June 25, 2018, 12:13:54 PM
That looks good, quick work!  :thumbsup:

Thought of making a fuselage jig ever? I did


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 25, 2018, 02:28:59 PM
That looks good, quick work!  :thumbsup:
Thought of making a fuselage jig ever? I did

Thanks.
Quick? 30 hours!
Could have been done in two hours using disposable dinner plates.

Jig? Yes, thought of it.
Just before seeing your rugged one yesterday  ;D

Regards


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on June 30, 2018, 09:35:45 PM
Completed just before tonight’s deadline...


Title: Re: 15” Druine Turbulent build
Post by: KALYANPRODHAN on July 01, 2018, 10:18:27 PM
Nice sir.
Where is the CG? Please post flight video..


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on July 01, 2018, 10:30:17 PM
@kalyanprodhan da,
Thanks.
Am testing and will post CG position etc

But I’m more worried about members who have no idea of courtesy to other members.
Maybe you and I should block some of them, till Anwar blacklists them.
Regards


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on July 20, 2018, 10:35:51 PM
Was a bit surprised at the AUW of 20gms.

Then I removed the wheels and legs.

Back at 16gms!
Never knew that wheels could add 25%!


Title: Re: 15” Druine Turbulent build
Post by: Glidiator on July 21, 2018, 12:30:11 AM
Nice work KK. Is it suitable for indoor or outdoor?.
I have an Excel file that gives the calculation for rubber weight to be used based on model weight and other parameters. Will dig it out of my hard disc and mail it.
A friend of mine (Aeromodeller too) just returned from USA. Has brought me a 10:1 winder.
Master airscrew stripper is available on eBay. Got two of them. Can't do ultralight stuff without a good stripper. Also have a thickness gauge that jewellers use. The balsa sheets we get have quite a bit of thickness variation at different areas. The other jig one needs is a prop pitch gauge if one is making own props.
All this makes life easier when constructing and better results too


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on July 22, 2018, 08:50:47 PM
@glidiator,
Have a battery powered winder from HK. Cost about 650.
Good that I didn’t buy the manual one I found in London for £15!

Due to monsoon, have flown Pilatus and Turbulent only in the drawing room.

Don’t have a MasterScrew stripper.
But my 30 yr old home made one elicited wonder on a US forum  ;D


Title: Re: 15” Druine Turbulent build
Post by: Glidiator on July 22, 2018, 10:38:51 PM
Please post pics of your stripper.We have always had to innovate since a lot of things were unavailable or simply too expensive.
I too have a battery winder with counter bought from RCB.
But one cannot stretch wind with that as there is no hook in front. I have been using a simple hand drill with a thick wire hook fitted to the chuck. It has only a 1:3 ratio so lot of winds need to be done on it.


Title: Re: 15” Druine Turbulent build
Post by: K K Iyer on July 22, 2018, 10:53:38 PM
Lube?
Using Glycerin. Dries off in a day or two.
Castor oil?


Title: Re: 15” Druine Turbulent build
Post by: Glidiator on July 22, 2018, 11:09:48 PM
People have been using various concoctions for lube. Anything with softsoap or glycerine based should suffice I think. More important is to wash the rubber pat dry and store in refrigerator after the days use to remove any grit that will cause Knicks when wound tightly next time. Will need to apply lube before every use. One good way not to get palms slippery is to put the loop in a ziplock bag , put required drops of lube into it and rub bag well to coat loop properly.
Incidentally the winder I have got from USA is $25. Don't see why it is so expensive. Must be made in China anyway. Plan to 3D print the gears in tough ABS plastic at my friend's printing facility. Handle and casing can also be printed.