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Old Sep 24, 2010, 11:18 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
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Quote:
Originally Posted by novastar View Post
Actually, I want the direct opposite of you. I want the stiffer/stronger center section and will accept the extra weight, but want lighter wings and verticals. I can use a stronger spar than the older glass fiber spar used in the original. I have never had any problems with the original FunJet's wings and vertical stabilizers out beyond 100 mph, but below 120-130 mph.
A stronger spar does not increase the torsional stiffness of the wing panels. If I wanted a stiffer/stronger center section, I would just add some carbon fibre profiles.

You may want to check the weights - the center section, the turtle deck and the canopy weigh 192g, while the two wing panels weigh only 92.4g:

http://www.rcgroups.com/forums/showp...&postcount=115

The ordinary FJ parts weigh approx. half of that.

Jürgen
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Old Sep 24, 2010, 04:04 PM
Voltage is LiFe
novastar's Avatar
US East Coast
Joined Aug 2007
638 Posts
Quote:
Originally Posted by Jurgen Heilig View Post
A stronger spar does not increase the torsional stiffness of the wing panels. If I wanted a stiffer/stronger center section, I would just add some carbon fibre profiles.

You may want to check the weights - the center section, the turtle deck and the canopy weigh 192g, while the two wing panels weigh only 92.4g:

http://www.rcgroups.com/forums/showp...&postcount=115

The ordinary FJ parts weigh approx. half of that.

Jürgen
My only real reason for inserting a stronger spar would be to handle greater air loads during positive pitch changes at higher speeds.

As far as inserting carbon profiles into the "normal" center section, to me that is, "6 of 1 half a dozen of the other"; in other words, I already have added strengthening measures to the current structure which has added weight to the model. It would be nice to start out with a stronger/stiffer and cleaner structure at the beginning, even though it adds more weight, while in theory, should require less carbon profiles. I have seen your post previously about the weights of the foam parts.
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Old Sep 24, 2010, 04:30 PM
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53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by novastar View Post
My only real reason for inserting a stronger spar would be to handle greater air loads during positive pitch changes at higher speeds.
...
I have yet to see a FunJet "fold its wings" in flight - even with the standard GRP spar.

Jürgen
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Old Sep 24, 2010, 10:39 PM
Voltage is LiFe
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Joined Aug 2007
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Quote:
Originally Posted by Jurgen Heilig View Post
I have yet to see a FunJet "fold its wings" in flight - even with the standard GRP spar.

Jürgen
Nor have I seen a FunJet fold its wings in flight, but that does not mean that my personal experience is representative of all flyers. That's why I am still flying with the original GRP spar that came with my first FunJet and I am using "normal" FunJet wings trimmed-down, but if I were to exceed 130+ mph, then I might use a stiffer and stronger spar.
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Old Sep 25, 2010, 01:22 PM
You down with EPP?
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Houston, Tx
Joined May 2009
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But I have seen one catapult the motor and mount out the back at 120mph+

Stress cracks started just behind the wing spar on the fuse and worked their way to the motor mount.

I got 65 flights out of it before it went. It was built stock, no glass or extra CF.

Excited that the Ultra is a little tougher.
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Old Sep 25, 2010, 01:57 PM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by johnnyrocco123 View Post
But I have seen one catapult the motor and mount out the back at 120mph+
...
Are you sure, that you did not have a prop failure?

Jürgen
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Old Sep 25, 2010, 02:13 PM
You down with EPP?
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Houston, Tx
Joined May 2009
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Quote:
Originally Posted by Jurgen Heilig View Post
Are you sure, that you did not have a prop failure?

Jürgen
Yes, I actually took that 6x4 sport off after the crash and flew it on a Stryker.
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Old Sep 25, 2010, 02:27 PM
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53859 Niederkassel, Germany
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Quote:
Originally Posted by johnnyrocco123 View Post
Yes, I actually took that 6x4 sport off after the crash and flew it on a Stryker.
So your motor plus prop ripped off the model at 120mph, fell to the ground and you are still using that prop?

I would not risk a model for a such a cheap item.

Jürgen
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Old Sep 25, 2010, 03:07 PM
You down with EPP?
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Houston, Tx
Joined May 2009
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Quote:
Originally Posted by Jurgen Heilig View Post
So your motor plus prop ripped off the model at 120mph, fell to the ground and you are still using that prop?

I would not risk a model for a such a cheap item.

Jürgen
I did that day.
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Old Sep 25, 2010, 08:24 PM
Nemo in a blender
Connexxion's Avatar
The Netherlands-Amsterdam
Joined Mar 2007
940 Posts
Got my FJU this week and I'm planning on using stuff I already had on the shelf.
A Mega 16/15/4 motor,Jeti Spin 33 ESC and 2 MPX Nano-S servo's.Prop will be a APC 6x4 pusher.

Here's my question: Can I use those Nano's in the FJU?They seem to fit perfectly but I just read on the MPX site that they recommend the little gems called Nano Pro MG Digi 4 or the Nano Pro Karbonite.

And what performance can I expect from my set-up?Also wondering if there's a better prop size you guys know of for my motor+esc combination.

Thanks in advance.

PS: does anyone know of a way to keep the turtledeck removable?
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Last edited by Connexxion; Sep 25, 2010 at 08:35 PM.
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Old Sep 25, 2010, 09:44 PM
Registered User
Manila Ninoy Intl, Philippines
Joined Nov 2001
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FYI - Retail pack AL Motor Mount

#33 2606

I think this is the link at Tower:

http://www3.towerhobbies.com/cgi-bin...?&I=LXZWL5&P=7

$ 16.69
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Last edited by deadduck; Sep 25, 2010 at 09:50 PM. Reason: Added tower link
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Old Sep 26, 2010, 03:09 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by Connexxion View Post
Got my FJU this week and I'm planning on using stuff I already had on the shelf.
A Mega 16/15/4 motor,Jeti Spin 33 ESC and 2 MPX Nano-S servo's.Prop will be a APC 6x4 pusher.

Here's my question: Can I use those Nano's in the FJU?
...
For your drive system, the standard FunJet would have been more than adequate and a lot lighter than the Ultra.

In your case, you can use those Tiny-S, but I would go straight for at least some HS-65HB so you don't need to upgrade them when you go for more power.

No need for a pusher prop either. You can use normal props when flying elctric.

The turtle deck is a load carrying structure. If you want it removable, you need to add reinforcements to the wing/fuselage - see "normal" FJ thread.

Jürgen
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Old Sep 26, 2010, 10:14 AM
jbc
WHO's your DADDY!!!
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Australia, SA, Adelaide
Joined Sep 2009
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How To Handlaunch A Funjet (0 min 17 sec)
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Old Sep 27, 2010, 04:20 AM
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petranf's Avatar
Greece
Joined Jun 2007
139 Posts
that is so funny . I like your looney toons technique
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Old Sep 27, 2010, 06:47 AM
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Beaconsfield. West Australia
Joined Jul 2009
137 Posts
Hi Jurgen,i wonder if you might be able to give me some advice please.I am looking at two motors for my funjet (1) Turnegy 3648 1450 kv
(2) Scorpion SCHK 3026 1400kv
I would like to use a 5cell and would like about 1600 watts. If you could help i appreciate any advice . Max
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