Thread Tools
Oct 19, 2009, 01:07 PM
Scratch Builder
AlexanderB's Avatar
Thread OP
I managed to build the mockup for the flaps kinematic. It works better than expected. No twisting or whatever.

Problem will be the assembly of it. With the mockup I have all space I need and it was a pain anyway. There are some screws that will be easy accassible. In the end I think this is possible.

I'll install two servos for a "dress rehersal" and see how it behaves. I also plan to put some weight on top of the flap, put it upside down and see how the kinematic behaves under stress.

The only problem is: I have no idea what the stress will be in flight and I can only hope that it will perform well.

Alexander
Sign up now
to remove ads between posts
Oct 19, 2009, 02:36 PM
Rock On- Damon Atwood
dag214's Avatar
Quote:
Originally Posted by AlexanderB
I managed to build the mockup for the flaps kinematic. It works better than expected. No twisting or whatever.

Problem will be the assembly of it. With the mockup I have all space I need and it was a pain anyway. There are some screws that will be easy accassible. In the end I think this is possible.

I'll install two servos for a "dress rehersal" and see how it behaves. I also plan to put some weight on top of the flap, put it upside down and see how the kinematic behaves under stress.

The only problem is: I have no idea what the stress will be in flight and I can only hope that it will perform well.

Alexander
Perfect! looks great!
You are running into the same problem I am having with my B-36 flaps, how to make it scale, but also how to miniaturize the parts so they are strong enough to work, as well as how do you get it all to fit into the plane.

Great work.

DAG
Oct 22, 2009, 02:17 AM
Scratch Builder
AlexanderB's Avatar
Thread OP
Short Update: I did some testing with my mockup (w/o servos yet). But it seems to be too filigrane right now. Especially the 1.0mm Dural sheet seems to be too weak.

I have no experience how it will behave during flight. My only concern now is that the torque needed to extend the flaps will be too high. I put some weight on the flap and it turned out that it was quite hard to extend them. On the other side: this is only at the first some degrees. After that the force needed drops down a lot. But this is what happenes during flight I guess: the first degrees of extending the load on the flaps is quite low. The load increases the more the flaps are extended. The kinematic will allow that.

Conclusion: I will now draw all the parts in their final design and build one final flap where I hope no more changes will be necessary. The parts that are glued to the wing and the flap will be doubled so there will be no torque on the screws that are attached to the levers. So this will be even more to scale

Any comments welcome
Oct 23, 2009, 11:13 AM
Scratch Builder
AlexanderB's Avatar
Thread OP
Short update: I did some more planning on the kinematics (see picture). Any comments warmly welcome
Oct 24, 2009, 01:09 PM
Scratch Builder
AlexanderB's Avatar
Thread OP
Another short update: In now finished the design of the flaps kinematics. I drew all necessary parts and test-milled them from ABS plastics to meke sure everything fits. In now will build a flap that will be used in the plane.
Oct 24, 2009, 05:18 PM
Übung macht den Meister..
Deuce's Avatar
Sehr schön, Alexander! Es wird bald perfekt!

James
Nov 03, 2009, 09:25 AM
...design-build-fly-publish...
eye4wings's Avatar
This is looking SO good! I just love to see engineering like this even if I cannot hope to get close myself! I can only stand back and gawp in admiration.

I can't say I really understand what gramms are in practical terms, but if it is any encouragement not to worry unduly about weight - my latest went more than four pounds over my target weight of 15 pounds but still flies like a dream.
I am sure your DC-6 will too.
Nov 03, 2009, 11:39 AM
Scratch Builder
AlexanderB's Avatar
Thread OP
Thank you for your kind words, "eye4wings".

Actually I am sure that most of the people can do more than they think! Of course a certain commitment is necessary.This is my second scratch build. If I take a closer look at it: it's my first. I had a basic model plan for my frist project, my DC-3. But it was so far away from the Original plane that I designed the fuselage by myself. But this is not true eithe: I got so much help from a German Forum (look here: http://www.rc-network.de/forum/showthread.php?t=84936 ). Without that I would not have been able to achieve what I did. Of course at a certain point one just has to do it. And you have to judge the tipps you get. Not every tipp on an internet forum is perfect.

So I'd like to encourage those who like what I do (and lots of others do ) to start with their own scratchbuild: look for a plane you really like. Try to get as much information as you can. Drawings, manuals, flight reports, and of course pitctures (you sure know the source of pictures: www.airliers.net) whatever. Try to see the full scale plane at a museum or even better at the airport and try to get contact the the folks that operate it.

And: read books about scratch building. I read three or four of them to get a certain basic knowledge. Of course your first project may consist of a lot of trade offs. Accept that! Then, when the first parts are finished and temporary assembled, and look at and feel: wow, that's what I did! This is overwhelming.

So all I can say is: Yes you can
Nov 03, 2009, 11:42 AM
Scratch Builder
AlexanderB's Avatar
Thread OP
Quote:
Originally Posted by eye4wings
I can't say I really understand what gramms are in practical terms, but if it is any encouragement not to worry unduly about weight - my latest went more than four pounds over my target weight of 15 pounds but still flies like a dream.
I am sure your DC-6 will too.
Well as far as I'm concerned I like slow flying planes. But the heavier they become the faster they fly. What I try to do is: build as light as possible. Consider every unnecessary gram. In the end the plane will end up heavier than you had hoped anyway. So if I don't look at the weight of small parts it will end up way heavier than I had hoped

By the way: I aim at 6kg (less than 212oz or less than 13.3lbs) AUW. Come back to this after the maiden
Nov 06, 2009, 04:00 AM
Scratch Builder
AlexanderB's Avatar
Thread OP
There is not much visible progress: I milled the second set of the flaps support and levers and started building the second flap. Not much to see here.

But in the meantime I got the spinners. The front view is already all right. But I have to work at the side view

I also decided on the ESC I want to use. Mr. Ramoser, who builds these great variable pitch propellers, advised me to try a German manufacturer: YGE (www.yge.de) since their ESC are top of the art. They are quite expensive (99 EUR, approx. 150 USD), but they have great options:

First they start spinning the motor (and therefore the propeller) very, very slow. You can almost see each blade of the prop moving. I measured 180 rpm. I aim for a function that allows me to start each engine separate like full scale. That will be a show!

Second I can use each BEC parallel despite all usual ESC. And they add their current. With all four ESC I will get 12 A BEC. Plus they allow to connect a separate rx-battery as the last option if the main battery fails. Then I can at least land gliding (if i make it).

Third they offer a special Cap set that is connected directly to the ESC that includes 5 low ESR Caps. I talked to the owner of YGE and he told me the 1m battery - ESC line is no problem with that.

So now I solved that problem as well.

By the way I aim for 350W for each motor and use 3s Lipos. I have four 3s 2100mAh and four 3s 2400mAh all 30c. I plan to use three of them parallel giving 6300mAh or 7200mAh giving me at least 190A. But I will only use 140A in total at full power.

The four Motors also arrived from HK. I use Turnigy 35-36 910kV with 115g each. They were really a bargain: 17 bucks each. And they look good. First tests look promising.
Last edited by AlexanderB; Nov 06, 2009 at 04:11 AM.
Nov 08, 2009, 05:12 PM
Scratch Builder
AlexanderB's Avatar
Thread OP
Today I did some planning on the inboard nacelles again. In order to finish the design of the wing some things have to be done here. Especially I have to figure out how to actuate the gear doors and wether this has an effect on the wing design.

One thing that's really painstaking is the 7° dihedral of the wing in combination with the landing gear and the nacelle. Something I just have to check. Therefore I printed some of the formers and test fitted them. I was sort of astonished how well they fitted. This is due my lack of experience. But now I'm confident that the nacelles will wor out great.

BTW it too quite a while to find the right drawings and measures. I alway put a scaled bitmap in the background of my Illustrator file I work with. So I can see whether I'm still in the right direction. In order to fit the landing gear in I added some mm to the diameter of the nacelle. I also moved the firewall a little to the front. But these station diagrams help really a lot.

Drew a lot but didn't build.
Nov 10, 2009, 03:04 PM
Go FASST or go home...
Ben_E's Avatar
Awesome work Alexander!

Ben_E
Nov 12, 2009, 04:36 PM
Scratch Builder
AlexanderB's Avatar
Thread OP
Thank you Ben, for your kind words

I did a little part which of course is necessary before I mill the wing formers: the outer tube for the wingtube of the outer wing.

The wing tube is a regular tail boom of a T-Rex 450 helicopert. It's light and cheap (since I sold my T-Rex 450 for a 500) and fits perfect.
Nov 13, 2009, 05:32 AM
...design-build-fly-publish...
eye4wings's Avatar
It helps no end to have good equipment, which comes at a price I don't feel able to meet!
My admiration for your work is not only on the basis of the fine detail a well-equipped engineer can produce but the application to that detail.

I have to design anything I put into models to be capable of being made from basic sheet or wire by hammering, cutting and silver soldering. Any retract systems (and the models they fly in) I produce are only capable of being called 'sport-scale', which is why my latest build was a fixed undercarriage version.
If you wish to have a look at the model in the air (and two of the worst landings I have done with it!) it is on YouTube as 'DeHavilland Heron at Baldock'.
The model is somewhat bigger than yours at 144" so it is not surprising that it also weighs more.

Seems our philosophies regarding weight are pretty much the same anyway!


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Pitts S1S for 100 watts scratch build Mike Tully Scale Kit/Scratch Built 73 Nov 24, 2013 11:32 AM
Build Log Tony Nijhuis Douglas DC-3 Dakota kit Build. Basingstoke Roy Scale Kit/Scratch Built 74 Jul 07, 2013 05:25 AM
Build Log Protech Douglas DC 3 (Build) flyingrally Scale Kit/Scratch Built 10 Aug 08, 2010 04:02 AM
Yippee! DC-3 scratch build complete Lowboy Foamies (Scratchbuilt) 4 Nov 28, 2006 08:53 PM
Fokker F-100 scratch build airliner project Igwe Aneke Electric Ducted Fan Jet Talk 35 Jul 07, 2005 06:16 AM