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Grob G850 Strato 2c

Old 11-03-2010, 02:33 AM
  #1  
Turbineguy
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Default Grob G850 Strato 2c

As a sworn slimer pilot I resisted electrocution for a long time but finally relented and got myself a Mini Ultra Stik due in part to being familiar with them from owning two of the 40 sized ones. One with an OS 70 4-stroke and one with an OS 61 2-stroke. The MUS is powered with a Park 480 1020, Castle T-bird 36 Amp SC, E-flite 2100 30c on a DX6i. What can I say. The only time you have enough horsepower is when you have too much. The reason for going towards the electrics is due to time constraints. I'm a Medevac pilot in the Army and the big green machine keeps me busy lately. Electric is more convienient especially with the closest LHS more than an hour away and the closest established flying field the same distance the other direction. I started flying in '89 so I'm certainly not new to the hobby. I like unique designs or thing that are obscure. I used to scratch build exclisively and alot of those were twins of my own design. I miss the days of building and also miss flying twins as well which leads me to the actual subject of my first post here.

Since '99 I have had a desire to build a Strato 2c. Very few people have ever heard of it or seen a picture of it. The build looks straight foward and the flying characteristics will be pretty similar to a powered glider. In the interest of time savings I intend to pilage the wing from an NSP Kestrel 100 since it's the closest to the proper shape and is available in kit form for the modifications I'll need to do. This will yield a span of 100" giving it a fuselage length of about ~42" if built dimentionally scale. The prototype has a span of 185' 4" and a length of 78' 8". Depending on the wing chord which I'm unsure of (haven't been able to get NSP on the phone for over a week) I may scale up the fuse somewhat. Motocalc tells me that with a pair of Park 480 1020s, 2 40amp ESCs and one 3s 3200 pack flight times will be about 45-50 minutes depending on the prop at halfish throttle and top speed around 50-55mph. This is with an AUW of roughly 57-65oz. A set of the E-flite electric retracts and a lighting system will also be installed.

So here's the rub. The plane is so obscure that after months of searching and multiple e-mails to Grob, both here in the states and in Germany as well with no response from either, I have no three view drawings that are remotely usable. There are pictures on line of course and general info most of which is from the '99 Brasseys book that I already have but nothing in the way of schematics that I can use to size the fuse diameter, horizontal tail, vertical tail etc.

I would be interested in any comments and/or suggestions anyone has on this little science project I've gotten myself into. If anyone has any three views they can foward or a source for same I'd be eternally grateful. I'm also looking for suggestions on the best way to build the fuse as well.

EDIT-I can't post links yet since I don't have three posts at the moment. If your curious what I'm building a quick Google search for Strato 2c will net what your looking for. As soon as I get the other two posts I'll set up some links.

Tim

Last edited by Turbineguy; 07-03-2011 at 06:46 PM.
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Old 11-03-2010, 03:03 AM
  #2  
Bub Steve
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Cool!! post a few here Like a count-down so you can post them, Look'in forward to your
build, bubsteve
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Old 11-03-2010, 03:07 AM
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The other thing I forgot to mention thats going in the plane will be a small camera in the underside to take aerial photos. Seems fitting for a plane that could best be described as a modern German adaptation of the U-2.
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Old 11-03-2010, 03:09 AM
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Here's post three.
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Old 11-03-2010, 03:15 AM
  #5  
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OK so here's the culprit.

[media]http://www.spyflight.co.uk/images/jpgs/grob%20g850/Strato2C.jpg[/media]

[media]http://de.academic.ru/pictures/dewiki/71/Grob_Strato_2.jpg[/media]

[media]http://www.skytec-engineering.de/strato2c.jpg[/media]

[media]http://p4.focus.de/img/gen/6/O/HB6OXNpL_Pxgen_r_1100xA.jpg[/media]

Info of the Strato 2c.

http://en.wikipedia.org/wiki/Grob_Strato_2C

The NSP Kestrel 100 I intend to take the wing from. The dihedral will be removed other than a few degrees at the center along with the other mods for the build added in.

http://www.nesail.com/detail.php?productID=68
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Old 11-03-2010, 03:19 AM
  #6  
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very cool, bubsteve
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Old 11-03-2010, 03:27 AM
  #7  
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It's definitely very unique and I'm sure I'll be the only kid on the block with one. Should be pretty relaxing to fly as well. Stall speed of around 14-16mph without flaps. However the Kestrel has flaps that span 2/3s of the wing along with pop out spoilers on top and bottom of each wing panel totaling 80sq/in per side. Given that stuff and a wing loading of about 9-11oz landings should be less than eventful. I could probably toss in a 4000mah pack with no noticable change. Motocalc says that'll give me over 100 minutes of flight time at half throttle. Pretty cool.
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Old 11-10-2010, 11:30 PM
  #8  
LADDIE
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Here is the three view
Attached Files
File Type: pdf
scan0002.pdf (1.24 MB, 303 views)
File Type: pdf
scan0003.pdf (642.7 KB, 236 views)

Last edited by LADDIE; 11-10-2010 at 11:32 PM. Reason: Missing word.
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Old 11-11-2010, 04:01 AM
  #9  
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Awesome! That's exactly what I've been trying to find for months. Where might I ask did you find these three views and do you have any more info? Again thanks for posting those for me.
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Old 11-11-2010, 01:18 PM
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Sorry, but I do not know where I got them. That is all I have. Good luck with build.
Laddie.
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Old 11-11-2010, 09:44 PM
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No worries. Thanks again for three views which will be all I need to get the project rolling.
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Old 07-07-2011, 02:31 AM
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Well it's been awhile since I posted here but the maiden on the Grob was yesterday. All up weight is 6lbs 5oz. Power system is two Eflite 480 1020kv motors, two Castle Thunderbird 36s, a pair of Neu 2600 46c 3s packs and APC 12x6E props one pusher and one standard for counter rotation. I ended up using the wing from an Art Hobby Evolution 2.5m glider (very nice guys to work with BTW). Span is 98.4" length came out to 54". Everything but the wing was all designed and built from the three view drawing provided to me by Ladislov back in November (thanks again Ladi).

Ok how does it fly? Quite well and very scale. I had originally planned on 4-5lb AUW but like most planes they get fatter as the design goes along. Wing loading worked out to around 22oz/ft but it tends to fly like a moderately loaded trainer. It cruises along at 1/2 throttle and seems to be happy there with full throttle not giving it much more speed likely due to the high drag from the engine nacelles.
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Old 07-07-2011, 02:36 AM
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kenchiroalpha
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Hi Tim
Outstanding
Pleased to meet you
How did i miss this one
First off, I would like to thank you for your service, i salute you
Wow shes gorgeous
Congratulations on the maiden
May she bring you much enjoyment in the years to come
Take care
Yours Hank
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Old 07-07-2011, 02:55 AM
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Some pics of the tail feathers. I used carbon veneer for the vertical fin with an internal balsa and basswood frame work. The channel up the center is for the pivot arm that connects the elevator linkage from the servo at the bottom to the elevator at the top of the fin. The pivot arm is made from .060" carbon and pivots on and aluminum tube and two ball bearings in the center of the fin. The horizontal is built up from 1/16 balsa skin and 1/8" balsa and basswood internal frame work. I went this route because it came out stronger, straighter and lighter than using 1/4" sheet for the same piece.
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Old 07-07-2011, 02:58 AM
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More tail pics
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Old 07-07-2011, 03:01 AM
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Fairing on top of the fin is magnetic and horizontal is removable for transport and incidence adjustments.
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Old 07-07-2011, 03:07 AM
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Here's some pics of the radio gear and removable battery tray in the foward fuse. The cockpit is a removable hatch that allows access to the battery tray servos and radio stuff. I'm using a DX8 so in addition to the RX there's also a TM1000 telemetry module.
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Old 07-07-2011, 03:15 AM
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Wing mount structure and my nifty carbon and balsa pushrod guides.
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Old 07-07-2011, 03:31 AM
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Originally Posted by kenchiroalpha View Post
Hi Tim
Outstanding
Pleased to meet you
How did i miss this one
First off, I would like to thank you for your service, i salute you
Wow shes gorgeous
Congratulations on the maiden
May she bring you much enjoyment in the years to come
Take care
Yours Hank
Thank you for the compliments and pleased to meet you as well. I have alot more pics of the build that I'll post up when I get a chance. It'll certainly be interesting the first time I take to the club field the first time. I'll probably spend much more time explaining what the heck it is than I will flying it.
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Old 07-07-2011, 12:01 PM
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Originally Posted by Turbineguy View Post
Well it's been awhile since I posted here but the maiden on the Grob was yesterday. All up weight is 6lbs 5oz. Power system is two Eflite 480 1020kv motors, two Castle Thunderbird 36s, a pair of Neu 2600 46c 3s packs and APC 12x6E props one pusher and one standard for counter rotation. I ended up using the wing from an Art Hobby Evolution 2.5m glider (very nice guys to work with BTW). Span is 98.4" length came out to 54". Everything but the wing was all designed and built from the three view drawing provided to me by Ladislov back in November (thanks again Ladi).

Ok how does it fly? Quite well and very scale. I had originally planned on 4-5lb AUW but like most planes they get fatter as the design goes along. Wing loading worked out to around 22oz/ft but it tends to fly like a moderately loaded trainer. It cruises along at 1/2 throttle and seems to be happy there with full throttle not giving it much more speed likely due to the high drag from the engine nacelles.
It is great that you built this unique plane. Glad I could help.
Laddie.
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Old 07-07-2011, 12:49 PM
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Wow, Beautiful Plane and build Gee, How did I miss this thread Glad your plane flies good for you, Take care and have fun, Chellie

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Old 07-07-2011, 10:04 PM
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Originally Posted by CHELLIE View Post
Wow, Beautiful Plane and build Gee, How did I miss this thread Glad your plane flies good for you, Take care and have fun, Chellie
Thanks Chellie. This is not my first scratch project but its been the first one since about '99 and probably my most ambitious so far. I tried a bunch of new things with this one that I hadn't done before technique wise so it was a good learning process as each build should be. Here's a few more pics.
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