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Old Apr 19, 2012, 02:09 PM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Here's what iv'e been putting together, a bit rough round the edges at the moment, a scaled down frogfoot to test out c of g , i call it the 'tadpole'!!! .

Phil
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Old Apr 20, 2012, 01:30 PM
it wasn't me flying that plane
Hover or die's Avatar
United States, NC, Wilmington
Joined Mar 2011
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Phil,
Have you thought about the CS 10 blade fan for the 25?not sure about the comparable amp draw but they do sound incredibly good in the videos I've seen..
I checked out the dolly in the other thread and what a cool idea...i usually do sliding takeoffs with my scorpion and the sand and grass that is sometimes ingested is hell on the leading edges of my rotor blades..I use 3 sliders made of thick plastic and they are perfect on asphalt but the grass takeoffs allow to much debris in the air intakes..
The dolly idea would be great for solving this problem..
Take care and good luck with the scaled down version............chris
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Old Apr 20, 2012, 01:48 PM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Hi Chris, must admit i never considered the CS. Do you know if it has similar dimensions to the Minifan? Trouble is the ducting and fan mounts are installed to suit the Minifan so which ever fan i choose it needs to be similar.

Phil
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Old Apr 20, 2012, 06:54 PM
it wasn't me flying that plane
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Is that one 70 or 90mm Phil?
If you have time check out the 2 threads over in ducted fan talk forum...there's one on the 70mm and 1 on the 90mm and they are full of info...lots of videos as well to hear the great sound...
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Old Apr 20, 2012, 10:49 PM
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St.Catharines, Ontario
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Phil. Long time no speak. how's things? the froggy and the tadpole are looking good. I gotta get my butt moving on the Jag. LOL.
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Old Apr 21, 2012, 03:51 AM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Hey Rich, been a while. As you can see not much happened really, but now weather is improving im all out to get this bird in the air. Got to get it done soon as i have a 'minor distraction' of my wedding to plan for september . Damn this leap year . I have been watching with anticipation for any activity on your Jag thread, any further progress with the plan?

Chris, it would be the 70mm fans, i should imagine they would be pretty much the same dimensions as the minifan, i'll check out those threads. Btw, anyone know if the CS70mm are available over here in the UK?

Cheers, Phil
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Old Oct 01, 2012, 06:00 PM
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Denver CO
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So an updates? I have a set of 64mm and figured why not an su25.
What was the scale of this bird? Final weight, wing span, spec in general

what airfoil does it use?
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Old Oct 02, 2012, 04:58 AM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Hi D, no more updates as yet. Got married 3 weeks ago and just back from honeymoon, so as you can imagine my attention has been diverted away from the the 'froggy' for some time now. Soon to be rectified. I think it would have to be scaled down to accomodate 64mm fans. Here's the spec:
Scale 1/9th
Span 66''
Length 63''
Wing Area 510 sq''
AUW approx 7 1/2 lb ( prototype has come out a bit more than this ).
Gives a wing loading of 34 oz/sq''. Seems a little high but it does have a large fuselage area.
Twin 70mm fans ( yet to be confirmed ).

Phil
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Old Oct 02, 2012, 09:27 AM
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Congratulations.

wow 7lbs

I was thinking some where around 3.5lb for a twin 64mm,Maybe I was to optimistic.

Maybe ill try my luck at bifurcated ducts and a single.
No stations have been cut its purely a 3d model at this point, with a bit of math.

http://www.rcgroups.com/forums/showthread.php?t=1743938

any tips would be appreciated. I've read through quite few of the su25 threads, whats here anyways,not a popular plane i guess. All seem to come out nose heavy.
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Old Oct 02, 2012, 11:43 AM
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Do either of you have 3D files that you're up to sharing?
I want to cut a Cy-39 bifuricated 90 = twin 64.

The 39 can give a little more internal room for the duct to snake over the main gear compartment.

I'll be cutting from sections of blue foam.

Oh Jumpy congrates on the getting married thing... Like having children its just one more thing to pull you away from the hobby.... Which isn't entirely a bad thing
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Old Oct 02, 2012, 12:07 PM
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Well as you see I'm working on a model now . No ducting has been done atm
Ill be happy to share what I come up with.
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Old Oct 02, 2012, 02:48 PM
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Congrats Phil. It seems like noone knew. You coulda PM'd me or something. LOL. Just don't let her interfere with the hobby too much. LOL. And get your mind out of the gutter and back into the plane. Hahahahahaha.
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Old Oct 02, 2012, 10:07 PM
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Quote:
Originally Posted by Maxthrottle View Post
The 39 can give a little more internal room for the duct to snake over the main gear compartment.
\
Im i misunderstanding you?
Is the single edf giving you the more room?
Or is there something other then cockpit/turtle neck arrangement.
I was under the impression the 39 is the same airframe except
new turtle neck to house the updated electronics and pilot placement, powerplant, etc...?

From the refs i have i cant see any wider fuse,or even wingspan on my ref sites?
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Old Oct 03, 2012, 03:47 AM
You are a "go" for reentry
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Quote:
Originally Posted by D_FAST View Post
Im i misunderstanding you?
Is the single edf giving you the more room?
Or is there something other then cockpit/turtle neck arrangement.
I was under the impression the 39 is the same airframe except
new turtle neck to house the updated electronics and pilot placement, powerplant, etc...?

From the refs i have i cant see any wider fuse,or even wingspan on my ref sites?
The 39 just has the hump on its back. So more internal fuse area.

I also wanted this one because the Bifurcated with retracts sits a little higher and blocks most of the passage to the tail. So I wanted to go with the 39 cause everything can go over the top via the hump.

That's an opinion from manually scaling out the area of the intakes to the size of a single EDF and gear clearance.

Jumpy said it already the tail nozzles do sit a little wide for a Bifurcated. So the fan has to sit almost equadistant from the inlet to exit to minimize sharp bends to the duct. To smooth that out again raising the fan to the roof seemed the direction to go.
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Old Oct 03, 2012, 04:05 AM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Thanks guys, no problem getting back to the 'froggy' Rich, she only said to me last night ' when are you going to finish that plane upstairs, i want to see if it flies or not '. LOL
Just checked out your blog D, looks very interesting. Is that sketchup your using for the 3d model? The only problem i can see with a bifurcated duct is that the exhausts are some distance appart meening more acute bends in the exhaust ducting, but i guess todays power systems can overcome any losses in the ducting. I'll be following with interest.
I think what Maxthrottle was saying about more room for ducting is that if using retracts the gear folds into the fuselage taking up quite a bit of space right where you would ideally want the inlet ducting to be, but saying that your right in that there is no difference between the 25 or the 39 in that area. I've already redesigned my 25 plans to accept retracts and also to be considerably lighter.

Phil
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