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Old Nov 08, 2012, 06:42 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
3,117 Posts
With all your fuel ahead of the CG.. I would balance the plane upside down with the tanks 1/3 full. With gear up or down depending on which way the nose gear folds(i cant remember)

98mm is good. 100mm is perfect. Balance for 98 and if you go less than the 1/3 in your tank your CG will move back to the 100mm mark(hopefully not more)

Nice install BTW
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Last edited by vettster; Nov 08, 2012 at 06:53 PM.
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Old Nov 18, 2012, 04:04 PM
It's like an addiction!
Downwind3Zero's Avatar
NY, Rochester
Joined Oct 2003
1,501 Posts
Looking for best, thermally stable 90mm Jetfan combo for 8S with HET motor. I am looking at either the 1500 or the 1680kV. Any one have any experience? I have looked at the V2 table by eJet.
Also, if you have suggestions for electric retracts that would be great!
Chris
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Last edited by Downwind3Zero; Nov 18, 2012 at 04:37 PM.
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Old Nov 18, 2012, 06:45 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
3,117 Posts
I can tell you from experience that for the past 3 years I have used an ARC 36 75 1t 1650kv motor and its still running. Rated for 6s but I only used it on 8s, 9s, and twice on 10s. Now thats saying something

The jetfan is one good unit. It has the wooosh that everyone likes, but dosnt explode or draw massive amps like the CS12. Ive never owned a Jetfan but I have only heard good reviews about them.
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Old Nov 18, 2012, 08:07 PM
It's like an addiction!
Downwind3Zero's Avatar
NY, Rochester
Joined Oct 2003
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The Jetfan 90 draws 116A with the ARC 36-75-1. That's a little too high Amp and too short flight time for me. Thanks for the information though.
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Old Nov 18, 2012, 08:55 PM
Registered User
Colorado Springs, Co
Joined May 2002
93 Posts
Quote:
Originally Posted by Downwind3Zero View Post
Looking for best, thermally stable 90mm Jetfan combo for 8S with HET motor. I am looking at either the 1500 or the 1680kV. Any one have any experience? I have looked at the V2 table by eJet.
Also, if you have suggestions for electric retracts that would be great!
Chris
Can't comment on either motor on 8S - but the JetFan 90 with HET 1400 on 10S comes down with the packs just barely warm.....
Hope that it gives you another realistic data point.
Greg
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Old Nov 18, 2012, 08:56 PM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
3,117 Posts
No problem.. But if your looking at keeping your amps down, then you have to go with the 1500kv or less. 1680kv like you mentioned wont give you what your asking for on 8s
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Old Nov 19, 2012, 04:22 AM
It's like an addiction!
Downwind3Zero's Avatar
NY, Rochester
Joined Oct 2003
1,501 Posts
Thanks to both of you! Vettster, so you mean too high Amps or thermally at limit on 8S?
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Old Dec 04, 2012, 09:09 AM
Why kamikaze pilot wear helmet
mikes68charger's Avatar
United States, OH, Columbus
Joined Jul 2010
1,086 Posts
Has anyone made this bad boy into a prop pusher jet?

I'm sick of edf but I can't find a prop jet that I like.

I was thinking of this bad boy with 5000mAh 6s 40 as I got a to of them, 60-120 eflight retracts

Those with retracts, could you tell me how big of a prop one could get on the back and still let it rotate

What you guys think?
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Old Dec 22, 2012, 09:01 PM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,796 Posts
I'm a bit stuck.

I am looking at buying this or the cmp L-39. I have a wemo with a Arc 36-75-1.5 and 12s 3300 40c batts. I was looking for a cheap home for it, but I'm not sure even this viperjet can handle it. I am used to flying heavy fast planes, I am not worried. What I am concerned with is the landing gear issue and if the Viperjet can handle the weight better than the L-39. I assume the L-39 can't do a lightweight 12s system, so I am back to the viperjet. The part that throws me off is the wingspan is a bit more, but by the specs, the L-39 has more wing area and less loading than the viperjet.

Are there any persons who have owned both? Which is better to go with? I am not afraid to build and modify, I do that with all my planes. I want to be realistic about the viperjet's capabilities. I would rather get the viperjet, but if it is more trouble than its worth, I will get the L-39 and go 8s.

Thoughts? Thanks ahead of time.
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Old Dec 23, 2012, 09:28 AM
"Take Off" eh!
vettster's Avatar
Canada, ON, Beeton
Joined Aug 2008
3,117 Posts
Quote:
Originally Posted by mattyhawk View Post
I'm a bit stuck.

I am looking at buying this or the cmp L-39. I have a wemo with a Arc 36-75-1.5 and 12s 3300 40c batts. I was looking for a cheap home for it, but I'm not sure even this viperjet can handle it. I am used to flying heavy fast planes, I am not worried. What I am concerned with is the landing gear issue and if the Viperjet can handle the weight better than the L-39. I assume the L-39 can't do a lightweight 12s system, so I am back to the viperjet. The part that throws me off is the wingspan is a bit more, but by the specs, the L-39 has more wing area and less loading than the viperjet.

Are there any persons who have owned both? Which is better to go with? I am not afraid to build and modify, I do that with all my planes. I want to be realistic about the viperjet's capabilities. I would rather get the viperjet, but if it is more trouble than its worth, I will get the L-39 and go 8s.

Thoughts? Thanks ahead of time.
I actually started this thread and have built and flown the Viper. I also have built and flown the HK L-59(same as the CMP L-39)

As much as it pains me to say..(not really lol) The L-59 is by FAR a better all around model.

Its lighter.
Has less wing loading.
Has more room for retracts.
The edf hatch is much more excessible
Can carry 12s if you desire as it does have a tail heavy situation and could only benefit from the extra weight up front.
It will fly Dead Slow! Or Super Fast which was a suprize given its straight wing.

The Viper is a very good model!! But the L-59 can do so much more

I sold mine(gone 100% turbine) but my buddy is currently making it into a 12s setup.

PM me if you have any questions
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Old Dec 23, 2012, 02:23 PM
Fill'er Up!
mattyhawk's Avatar
Oxnard, Ca
Joined Oct 2008
1,796 Posts
Thanks vett, I appreciate the input.
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Old Dec 24, 2012, 05:56 AM
It's like an addiction!
Downwind3Zero's Avatar
NY, Rochester
Joined Oct 2003
1,501 Posts
I don't have the L-59 to compare but I am building the Viper and like it. The Eflite 15-25 retracts fit perfectly and I had TAM make some struts to appropriate length. Haven't flown yet. Most of the problems with the early kits have been solved (paint flaking, cutouts for elevator servos).
Chris
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Old Jan 04, 2013, 10:03 AM
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choopi's Avatar
New Brunswick
Joined Feb 2006
1,194 Posts
Anybody got a leftover canopy that is for sale?
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Old Jan 09, 2013, 03:39 PM
Registered User
Joined Jan 2013
21 Posts
Gents,
I am starting to build Viper now and wanted to check which servos better to use for ailerons?
I have some spare HK939MG servos, but are they strond enough for this purpose? Or shell I try something bigger?
Thanks!
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Old Jan 09, 2013, 06:39 PM
It's like an addiction!
Downwind3Zero's Avatar
NY, Rochester
Joined Oct 2003
1,501 Posts
Should be OK if you don't plan on overpowering the Viper.
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