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Old Aug 13, 2013, 12:15 PM
Fast Jets for Fast times
Lmeano_from_MO's Avatar
St. Peters MO.
Joined Nov 2007
1,210 Posts
Great work D,

Looking forward to the 90mm version. A retired RC builder passed along a hotwire fuse cutting table that he never got to used along with wing bows. The wire bow is vertical to the table for resting the part. It would make it easy to follow section paterns like in your design.
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Old Aug 14, 2013, 06:08 AM
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D_FAST's Avatar
Denver CO
Joined Apr 2008
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Will the guys that are looking forward to a 90mm version chime in on some of the electronics.

Like commonly used retracts,struts, cell count, lipos, etc so i can get these modeled up, to place into the scene to start working out the litply parts any dimensions or links would be great.

@ Airx, i may have fumbled on the FCS sheet, i was looking over them last night and noticed i did not number them, and one seems to be out of place as it doesn't have the edf hatch or hardwood knock outs, but is lying between two that does.
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Last edited by D_FAST; Aug 14, 2013 at 06:29 AM.
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Old Aug 14, 2013, 06:43 AM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,535 Posts
Hi D,

I will looked at them just now and sht15 is the one, I dont think it will be a problem, I can draw it in if it will be a similar setup to the one before and the one after.

Eric B.
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Last edited by AirX; Aug 14, 2013 at 06:45 AM. Reason: Changed sentence
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Old Aug 15, 2013, 06:31 AM
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D_FAST's Avatar
Denver CO
Joined Apr 2008
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Spent some time on the 90.
preliminary measurement at 1/12 scale has a rear tire scale of 2.5"
this won't fit into the wheel well. im finding most 2.5"wheels are 20-24mm wide.
to wide for the wells.
Things are getting tight as well in other areas
im thinking i need to go up some more in scale. but this will increase the inlet fsa well beyond. 100%
thoughts? ideas there larger scale is a new realm for me.
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Old Aug 15, 2013, 07:25 AM
Da' Cajun
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Lake Charles, Louisiana
Joined Jun 2009
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100%+ FSA won't necessarily hurt fan performance. Only thing would be increased drag.
But I would gladly trade a little drag for some room inside the fuse.

The MiG 19 I'm building (or not building ) is going to have a huge inlet, well over 100% FSA.
Really not that concerned about. Remember, most of those store-bought-foamies have gigantic intakes and fly pretty decent.
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Old Aug 15, 2013, 09:17 AM
EDF rules... :)
AirX's Avatar
Joined Nov 1999
13,535 Posts
The larger airframe will fly better and the larger inlets wont kill speed like Boogie says, the reason is at equilibrium flight the plane cant fly faster than the air the fan is pushing out the exhaust so there is always a lower pressure at the inlet. The caveat is when the throttle is closed there is a little more drag compared to a smaller inlet. Scale would be compromised if the inlets are smaller than the real one, so no problem.
there is one way you can help it though and that is to make the wall thickness larger at the inlet so it can be rounded which makes the inlet more efficient.

Eric B.
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Last edited by AirX; Aug 15, 2013 at 12:49 PM. Reason: Added "equilibrium flight"
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Old Aug 15, 2013, 09:24 PM
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Denver CO
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thanks guys. ill keep plugging away at it.
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Old Aug 16, 2013, 02:56 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,039 Posts
Quote:
Originally Posted by D_FAST View Post
Will the guys that are looking forward to a 90mm version chime in on some of the electronics.

Like commonly used retracts,struts, cell count, lipos, etc so i can get these modeled up, to place into the scene to start working out the litply parts any dimensions or links would be great.
Light (6s) or heavy (12s) 90mm? With such a broad range in the 90mm category (weight wise) what are your thoughts? I'm not trying to play the devils advocate, but a full blown 12s set-up, with gear, and struts, has to be in the 10 to 12lb range. Which means. most retracts will be a minimum of 1" deep. Will there be an issue with wing thickness (chord depth at location) I just ordered these for my F-86 Sabre. thinest I could find at 1" thick. http://www.robart.com/products/90-de...obostrut-ready

Even at 12lb, wing loading should not be an issue. Plenty of SQ/IN
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Old Aug 19, 2013, 01:31 PM
Fast Jets for Fast times
Lmeano_from_MO's Avatar
St. Peters MO.
Joined Nov 2007
1,210 Posts
Quote:
Originally Posted by D_FAST View Post
Will the guys that are looking forward to a 90mm version chime in on some of the electronics.

Like commonly used retracts,struts, cell count, lipos, etc so i can get these modeled up, to place into the scene to start working out the litply parts any dimensions or links would be great.
D,

These are the parts I use for my 90mm jets. Low cost but so far the parts have held up. On bench test I got 6lb 12oz of thrust with this set-up that is pushing 2 F-4's to over a 100mph.

Batt
http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html

ESC
http://www.hobbyking.com/hobbyking/s...ESC_Opto_.html

retracts for up to 10lbs
http://www.hobbyking.com/hobbyking/s...1mm_Mount.html
Starmax 5 blade 90 mm fan

EDF motor
http://www.hobbypartz.com/96m812-3674-1700kv.html
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Last edited by Lmeano_from_MO; Aug 19, 2013 at 01:39 PM.
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