I guess you missed the bit below the video " Prototypeneinbau – die Rumpfspalten verschwinden in der Serie natürlich"

Means "single prototype, the gaps will naturally disappear in series production."


Google translate would have told you that too but you have to know you need to use it, I guess.

In any case on the contracting part of the fuselage like that the flow is turbulent and the boundary layer is fairly thick.

The boundary layer is defined as the distance from the surface where the flow attains 99% of the free stream velocity. The velocity profile isn't linear but about 40% of the thickness from the surface the flow will be at around 2/3rds the free stream velocity n turbulent flow.

A reference I found said the boundary layer grows about 16mm per meter from the leading edge assuming all turbulent flow so aft of around half way along the canopy the flow is turbulent and a couple of meters aft of that will be about 32 mm thick. Any small

discontinuities there are buried deep in the boundary layer and don't see anything like free stream velocity. Drag depends on velocity squared so very little drag.

Now the FES is on the nose and there might be a little laminar flow on the spinner in front of the prop so the boundary layer is very thin there when it encounters the folded prop which will cause it to turbulate and the folded prop will see most of the free stream velocity.

FES will certainly cause loss of significant amounts of the laminar flow that is otherwise present on the front of the fuselage.

Mike









At 10:53 PM 9/21/2016, you wrote:
Content-Type: multipart/alternative;
        boundary="----=_NextPart_000_011B_01D2145A.FCB61810"
Content-Language: en-au

You’re worried about the increased drag from a FES?
Looking at that video, I’d be more concerned about the increased drag from that appalling panel fit, never mind the huge gaps and the numerous screw heads. Look at the rear, where the pylon extends: that panel is sticking about 5mm above the fuse.
It looks like a dodgy home-built botch job.

Btw why not make the thing extend towards the fuse? I can’t recall if the motor was too wide, and life is too short to wait for it to load again…


From: Aus-soaring [mailto:aus-soaring-boun...@lists.base64.com.au] On Behalf Of Mike Borgelt
Sent: Tuesday, 20 September 2016 7:26 PM
To: Discussion of issues relating to Soaring in Australia.
Subject: Re: [Aus-soaring] electric self launch

At 07:04 PM 9/20/2016, you wrote:

Any  good links?
I found a schematic diagram which indicates that the motor has a pusher folding prop. Not sure how it retracts and fits in the fuselage with the blades sticking up?


Here you go: <http://www.gpgliders.info/technik/>http://www.gpgliders.info/technik/ Scroll down to the videos. They took quite a while to load here. The link seems slow.
Sheer bloody genius I think.

Mike


Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978
<http://www.borgeltinstruments.com/>www.borgeltinstruments.com
tel:   07 4635 5784     overseas: int+61-7-4635 5784
mob: 042835 5784                 :  int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
Aus-soaring@lists.base64.com.au
http://lists.base64.com.au/listinfo/aus-soaring

Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978
www.borgeltinstruments.com
tel:   07 4635 5784     overseas: int+61-7-4635 5784
mob: 042835 5784                :  int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia  
_______________________________________________
Aus-soaring mailing list
Aus-soaring@lists.base64.com.au
http://lists.base64.com.au/listinfo/aus-soaring

Reply via email to