Don't forget to check your spam folder if you don't get an activation email after joining!!

Scheibe Spatz

Let us all watch your new project progress.
StephenB
Posts: 146
Joined: 26 Dec 2018, 08:45
Location: Hungary

Scheibe Spatz

Post by StephenB »

The model as designed by Chris Williams as an A-Spatz or, as Chris describes it, a "Spatz 1" is at a scale of 1:3.5 giving a wingspan of 3.8 metres. Early examples built by Scheibe were designated A or B, followed by the later L version, it's difficult to find online sources for verification of the differences, most A types seem to be without a wheel, some have shoulder mounted wings, some top mounted and canopies seem to vary too. So, not easy to find a full size to accurately model, mine will probably end up as this:

Screenshot 2020-06-03 at 20.51.12.jpeg


To speed the build process I ordered the laser cut short kit and plan from Cliff at Laser Cut Sailplanes, the parts all neatly packaged and bagged according to their use - left wing ribs in one bag, right wing ribs in another and so on. Balsa sheet and strip, spruce strip and ply were sourced along with the electronics, covering material and various hardware to produce a complete kit of parts:

IMG_0266.jpeg

The Bridson jig was deployed and the laser cut former supports were glued to the adjustable angle pieces with CA before sliding in to position and checking for correct alignment referenced against the dimensions marked on the plan:

IMG_0270 (1).jpeg

The 1.5mm ply keel was strengthened by adding 1.5mm ply doublers in the wheel box area before glueing both sides on to formers 2, 3 and 4 with aliphatic. This assembly was then dropped on to the jig where the 6mm square spruce longerons could be added:

IMG_0289.jpeg

Dale Nicholls
Posts: 8
Joined: 19 Mar 2015, 09:44
Location: Australia

Re: Scheibe Spatz

Post by Dale Nicholls »

StephenB,

Here is some inspiration for you. The model turns out very nice and is a great size.
The overall handling is very benign, enjoyable to fly.
If you have any questions or queries please reach out.

Dale Nicholls
Spatzcloseup.jpg
DSC_1561.jpeg
Landing2.jpg

StephenB
Posts: 146
Joined: 26 Dec 2018, 08:45
Location: Hungary

Re: Scheibe Spatz

Post by StephenB »

Hello Dale, nice job!

Did you build from the plan or the laser cut kit? Any challenges in the build that you had to overcome?

Dale Nicholls
Posts: 8
Joined: 19 Mar 2015, 09:44
Location: Australia

Re: Scheibe Spatz

Post by Dale Nicholls »

Hi there Stephen,

my model was handcuff off the plans, so no laser cut parts involved.
I followed the plans in all respects and its a well conceived design as you would expect from Mr. Williams.
The only suggestion I would make is to update the elevator connection to a ball link fitting (as per his later designs) to make it easier to detach and attach the stab. The model flies very well and is an easy flyer.

I have many photos during the build so if you have a question please ask.

enjoy the build.

Dale

IMG_0509.JPG

StephenB
Posts: 146
Joined: 26 Dec 2018, 08:45
Location: Hungary

Re: Scheibe Spatz

Post by StephenB »

The spruce longerons were bonder in place with the main one requiring some steam bending around the cockpit area, a removable cockpit floor was fabricated from liteply to allow access to cabling and the tow release servo:

IMG_0294.jpeg


I then set about adding the ply plates that form the wing box area, here I encountered a problem - the top plate H2 was a little undersize so required some fettling:

IMG_0288.jpeg


I then discovered that F4 didn't have the hole cut to accept the bottom longeron and F8 was not opened out at all, so nowhere for the pushrod to go! Of course I didn't spot these issues until after I had bonded them, in but F4 was easily dealt with in situ with the Dremel and F8 was carefully removed and opened out on the scroll saw. Onward and upward after this, 6mm square balsa cross bracing added and the ply sheeting glued on to the top decking:

IMG_0292.jpeg


Tow release servo added, this will connect via a Bowden out to a Multiplex aero coupling:

IMG_0298.jpeg


To get as much weight as far forward as possible a battery box was fabricated from birch ply to take the 4200mAh NiMH, this was epoxied in place and additionally secured with screws which will also give the car body filler something to key to when forming the nose:

IMG_0295.jpeg
IMG_0299.jpeg


A ply plate with captive nut for the tailplane retention was glued in place, a "paddle" to operate the elevator was fabricated from piano wire and brass:

IMG_0296.jpeg
IMG_0297.jpeg


With rudder, elevator and tow release servos in place the next job will be to sheet the forward fuselage.

IMG_0300.JPEG
Last edited by StephenB on 20 Jun 2020, 07:35, edited 1 time in total.

john greenfield
Posts: 551
Joined: 18 Mar 2015, 07:52
Contact:

Re: Scheibe Spatz

Post by john greenfield »

That looks like a very small and weak servo for a tow release, especially a Multiplex type with a retracting pin. When everything goes wrong on the tow you need a super reliable release system that will work under any load. As you have the space, may I suggest you fit a much more powerful servo.

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

StephenB
Posts: 146
Joined: 26 Dec 2018, 08:45
Location: Hungary

Re: Scheibe Spatz

Post by StephenB »

How much torque would be right for the release John?

I have no experience of these but Multiplex describe the aero tow mechanism thus: "To operate the release all you need is a low-cost standard servo and
a length of 1.2 mm Ø steel rod running in a snake outer sleeve.

User avatar
chris williams
Posts: 1177
Joined: 10 Mar 2015, 10:50
Location: Blandford Dorset

Re: Scheibe Spatz

Post by chris williams »

In my experience over a range of models, the MPX release works very well with a standard servo for models up to 22lbs. The advantage of this system over cam-in-a-tube variety is that very little movement is required to release, so the rod can be set in the innermost hole of the servo arm for max torque...

patte de loup
Posts: 19
Joined: 18 Mar 2015, 21:11
Location: Strasbourg ( FRANCE )
Contact:

Re: Scheibe Spatz

Post by patte de loup »

For testing the tow system , including the servo , you should be able to release by pulling the tow cable with a force equal to the weight of your glider. That's the rule, we apply for our GPR glider ( over 5 meters wingspan ) during the meeting.
Pat'

john greenfield
Posts: 551
Joined: 18 Mar 2015, 07:52
Contact:

Re: Scheibe Spatz

Post by john greenfield »

Stephen

I agree with all of the above. Min movement on the pin to get max torque from the servo and test the release to ensure it works (every time) with a pull at least equal to the weight of the glider.

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

Post Reply