Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
October 17, 2017, 05:21:01 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Building a 55' motor glider without a plan  (Read 834 times)
0 Members and 1 Guest are viewing this topic.
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« on: February 16, 2017, 12:50:42 PM »

Dears,
it all started out with an old glow O.S. .10 FP lying around and a sketch in 1:10 scale drawn in the sixties for a FF motor glider called "Barra". So I called the new project "Barra 2". How would I build a model without a plan? I started to cut out a ply tray for the essentials: motor, tank (Sullivan 2 oz), battery 4x1200 mAh NiMH and two 9g servos. These components were placed strategically an the tray and made the necessary cut-outs for the motor, tank and a hole for routing the servo cables upward. Done this I cut from a 5mm Balsa sheet two side pieces (all measures taken from the 1:10 sketch) and glued the tray to one side piece. Then I drew up the left fuselage side and glued all the sticks together, fixing the sticks to the side piece. You can see all that on the fotos.
Well, next time more.
Greetings,
Kurt
Attached files Thumbnail(s):
Building a 55' motor glider without a plan
Building a 55' motor glider without a plan
Building a 55' motor glider without a plan
Building a 55' motor glider without a plan
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #1 on: February 16, 2017, 03:16:36 PM »

Second part: what is the advantage, building a model without a detailed plan? During the building progress you have complete freedom to modify details according to your experience, a plan forces you to follow the ideias of others.
O.K. lets continue the building: when I cut out the hole for the tank I built a little box below it with a double purpose: first, that the tank would not fall through and the second to keep any fuel out of the fuselage, tanks may leak. As you will see on later pictures, the tank has a very easily acessible lid, so that you can clean it once in a while and see its level when fueling.
Te left part of the stick fuselage was built upon the right half for exactness of the dimensions and after having fixed the left front part glued on it and the joined the two fuselage halfs, see pictures (I dont know why all my pictures appear 90 degrees turned?) Then I soldered the front legs and fixed them flush with wheels attached to the fuselage.
Greetings,
Kurt
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #2 on: February 16, 2017, 04:48:46 PM »

It's progressing well Kurt. Good luck with it.

john
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #3 on: February 16, 2017, 04:53:58 PM »

Third part: some design data
-main wing 1400 x 200 mm (aprox 55" x 7.9"), streching rario 1:7, air foil Gö (MVA) 301, area 27,5 dm²
-stabilizer 400 x 150 mm (aprox 15.7 x 6") ratio 1:2,7, air foil Clark Y, area 5,7 dm² (20%, which is a bit small, normally values from 25 t0 30%, I shall report flight results)
-distance main wing - stabilizer 500 mm = 2,5 times main wing chord
-EWD 2,5°
CG theoretical 167 mm, the measured is much more forward, flight results will show the final one.
dihedral value 5%
Value are very conservative for high stability
Greetings
Kurt
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #4 on: February 19, 2017, 03:59:27 AM »

A 20% tail should be fine Kurt as you I imagine you won't nbe using free Flight endurance aft CG positions.

John
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #5 on: March 19, 2017, 10:20:53 AM »

No John, the plane is just for pure fun and leisure flying. Here in Rio the competition is dead, unfortunately, like in many places in the world. People just buy ready foam toys from China and try to fly them without instruction. The result is that they desist after the first purchase. My last competition in Rio was already some years ago in the 2 meter glider class, towed up by a 100 meter (?, I dont even remember) nylon rope with 30 m surgial rubber tube.
Kurt
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #6 on: March 19, 2017, 10:47:01 AM »

Fourth part, stabilizer and rudder.
You can see the construction A4 pencil drawings, based on the original sketch. It'really growing. Motor already installed.
Kurt
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #7 on: March 19, 2017, 06:12:49 PM »

Neat work Kurt - progressing well.

John
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #8 on: March 23, 2017, 08:37:43 AM »

Fifth part, fuselage details and covering with poyesther sheet
The fuselage part has come to an end,
next time I shall start with the one-piece low dehidral (a bit less than 5%) wing, airfoil MVA (Gö) 301
Kurt
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #9 on: April 01, 2017, 05:14:43 PM »

Sixth part,
building the wings started with sawing-out a master rib from ply of the MVA 301 air foil. Then printing it on a balsa sheet and sawing out rib for rib with a very fine blade. I found out that cutting the ribs out with a knife would give a lot of cutting errors (this depends of course of the thickness of the balsa sheet and its hardness. I used a 3/64 (aprox 2 mm) medium hard sheet.
Gives you some work at full attention.
The first two pictures give you an idea of the already assembled left wing.
The next picture shows a trial of the completed wing on the fuselage.
The last picture shows the completely covered model in red and yellow, I think it has become a beauty, what do you think?
If it flies well I dont know, we shall see that after the first field trials.
I have a club collegue called Paulinho, who will perform the paper of the test pilot. I am too superstitious to make a maiden flight.
You shall hear from me the next days.

Greetings from Rio,
Kurt
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Re: Building a 55' motor glider without a plan
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #10 on: April 01, 2017, 05:23:29 PM »

I really do not know why all my pictures appear with a 90 degree left turn?HuhHuh
Anybody knows how to put them right in this forum??
Kurt
Logged
Prosper
Platinum Member
******

Kudos: 36
Offline Offline

United Kingdom United Kingdom

Posts: 1,115



Ignore
« Reply #11 on: April 01, 2017, 05:54:52 PM »

Kurt, this is very nice work. Personally, I completely agree that working with an idea is better than working to a plan. If you do work to a plan, you should have your own ideas about it Smiley.

About the 90° picture rotation, I see that picture 3 in reply #9 has the correct orientation. It looks to me as if the software you're using - in your camera, your cellphone, or your uploading interface to the internet, is set to a simple default wherein it detects a 'widescreen' ratio for the picture, and orients the picture accordingly, with a long horizontal and a short vertical. You may have to override or 'force' some "auto" or "default" setting, to get your images published the way you want them.

Regards,
Stephen.
Logged
hastf1b
Gold Member
*****

Kudos: 11
Offline Offline

Germany Germany

Posts: 373


Winding my Tilka during the german chamionship `87



Ignore
« Reply #12 on: April 01, 2017, 06:43:43 PM »

Hallo Kurt, ich habe dein schönes Modell mal gedreht. Wirklich sehr schön geworden.

Heinz
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Logged

F1B is o.k.
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #13 on: April 01, 2017, 07:37:25 PM »

Good looking build Kurt -very neat.

John
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #14 on: April 03, 2017, 10:41:03 AM »

Dankeschoen! So sieht das arme Modell ein bischen besser aus!
Kurt
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #15 on: April 03, 2017, 10:47:06 AM »

John and Stephen,
thank you for your comments. The "Barra 2 " satisfies me regarding beauty and execution. If , after all, it flies well we shall see on the flying field.
There are some risky ideas for a rudder-only model, like the very low dehidral of less than 5%.
Greetings from Rio,
Kurt
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #16 on: April 03, 2017, 08:22:07 PM »

Hmm yes I think you may have some trouble with that Kurt. However if you do just add some tip dihedral say 15 deg over the last couple of bays- or add ailerons.

I didn't notice the lack of ailerons.

happy flying.

John
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #17 on: April 04, 2017, 09:10:24 AM »

Tip dehidral is a good idea. It will not spoil the beauty and give the desired stability.
I built various models with tip dehidral and just rudder/elevator control which had a very good stability. (below you can see my V-51, a Karl Barth design from 1951)
After the maiden flight I shall report.
Greetings
Kurt
Attached files Thumbnail(s):
Re: Building a 55' motor glider without a plan
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #18 on: April 04, 2017, 07:31:40 PM »

Good luck with it Kurt. What a nice big flying area - local airfield?

John
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #19 on: April 05, 2017, 09:43:17 AM »

John,
it is the old military airport of Rio de Janeiro where our club (ACA) has two cement runways, one for the elctrics and one for the glow engine flyers, besides there is a large grass area for the gliders. You may see this under www.acarj.com.br .
Greetings,
Kurt
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #20 on: April 05, 2017, 07:41:30 PM »

Thanks Kurt. You have a very active group in your club.

John
Logged
cloudburstz
Bronze Member
***

Kudos: 1
Offline Offline

Australia Australia

Posts: 97



Ignore
« Reply #21 on: April 13, 2017, 05:14:14 PM »

Nice looking plane, great job.Did a few own designs when I was much younger, fun way to build.
Logged
Kurt
Silver Member
****

Kudos: 3
Offline Offline

Brazil Brazil

Posts: 130


Topic starter

WWW

Ignore
« Reply #22 on: July 26, 2017, 10:15:33 AM »

John and all other friends!
Here comes the first flight experience.
It was a desaster!
As I was very much afraid of the small rudder area and the low dehidral I gave the model to a friend for the first trial.
After a ground start it came up quite easily, but then went into a left curve from which it did not recover, crashing into high grass. Thanks god without damage.
Possible causes: CG too far behind, small rudder area, low dehidral.
To be on the safe side, I took the following counter-measures:
Adding some lead on the nose, increasing the rudder area and following the advice of John building two "ears" into the wing, both with 10% dehidral.
Now I was very curious about the result of so much precaution.
On the next flight I still did not trust in my poject skills and gave the "Barra 2"again to the same friend, Paulinho, who had flown it before.

You will not believe, it behaved like a lamb, the perfect Sunday flyer!!!
Perfect climb, perfect curve handling and good thermal ability, that means a flat slow glide.

I am absolutely happy! My design showed all the properties I intended to put into it.
Middle of August I shall be again in Germany and send some news from there.
Good Bye!!!!
Kurt
Logged
OZPAF
Titanium Member
*******

Kudos: 38
Offline Offline

Australia Australia

Posts: 3,538



Ignore
« Reply #23 on: July 27, 2017, 08:16:30 PM »

Well congratulations Kurt, I'm glad to hear that it survived it's first test flight without damage and the alterations worked. Its always far more satisfying when your own design works.

Now don't forget to put all the changes onto your plan Smiley

cheers
John
Logged
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!