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Viper assembly tips? - 10/23/2004 4:10:48 AM   
proptop



Posts: 4633
Joined: 10/18/2002
From: Rome, NY, USA
Status: online 		Guys, I just got a NIB Viper (for $85 bucks, so I didn't want to pass it up) and I'd like to know if there are any things I should look out for? You know, maybe a better way of setting it up or structural deficiencies? I'm not worried about it being class legal or anything, I just want something quick to assemble and that'll be (sorta) fast...
I was thinking of using my Magnum .52XLS w/ Macs pre tuned pipe? Or perhaps an MVVS .49 that I have set-up as rear exh. and mt. the eng. upright to run the pipe straight back over the wing. Also was thinking of an APC 9x9 to start with?
The servos I was thinking about are Expert SL451's w/a Hitec 555 Rx. and a AAA NiMh rx. pack. Is the stock tank gonna be o.k or will I need a bubbless type? I'm just going to be "sport" flying with it, so I don't plan on racing, unless one of my buddies sees how much fun I'm having and gets one too... Thanks, Tom.


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RE: Viper assembly tips? - 10/23/2004 1:51:29 PM   
daven



Posts: 7026
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		Prop Top,

Looks like your on the right path. Your receiver, servos, and battery will all be fine. The stock tank will be fine also, you will just need to set the needle slightly richer than if you went with a bladder set up.

I believe there were some viper tips on here earlier, but I believe the jist of the issues were the following:

The wheels are bad, and will pop off the axles. Replace them (www.darrolcady.com)
Replace the metal wing hold down bolts with nylon
Verify the incidence of the tail (I may be confusing with the predator)

I would suggest adding some 2 oz glass inside the nose area and firewall.

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(in reply to proptop)
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RE: Viper assembly tips? - 10/24/2004 1:35:02 AM   
proptop



Posts: 4633
Joined: 10/18/2002
From: Rome, NY, USA
Status: online 		Thanks Dave...I dug a little deeper into a search and found out about reinforcing the rear fuse. and checking the tail incidence too.


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RE: Viper assembly tips? - 10/24/2004 2:40:03 PM   
Ed Smith


 

Posts: 2875
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: online 		Proptop,

I have never owned a Viper Kit. In the interests of safety however I would consider the following. The Viper is an ARF designed and built for a .40 size engine. ARFs being what they are it is very likely it is not "Overbuilt". You intend to power it with a tuned pipe .52 size engine.

As Dave says, reinforce the nose area, or the firewall may head out leaving the rest of the airplane behind. It would be wise to check the incidences of all three components, Engine, Wing and tail. If these are in conflict you could have a real tiger by the tail on it's first flight. Take a close look at how the control surface hinges are affixed, some have been known to pull out. Are the control linkages tight with no play? if there is play you will get flutter and anything can happen

Any reinforcing and repairs that you do will add weight. This will put greater stress on the wing during flight. Is the wing structure adequate to hold up under the stresses you willl be imposing on it? Does the wing have a credible spar? Not just a piece of carbon laying flat under the skin, that is useless.

The foregoing is offered purely to help you keep the airplane in one flyable piece. Remember, I you do have an accident, you have exceeded the power recommendations of the manufacturer. You will be on your own in the insurance department!

Ed S

(in reply to proptop)
       Post #: 4

RE: Viper assembly tips? - 10/24/2004 3:36:17 PM   
proptop



Posts: 4633
Joined: 10/18/2002
From: Rome, NY, USA
Status: online 		Thanks Ed, I really appreciate the advice. Will definately do the incidence and thrust line alignment checks, and a little C F in the aft fuse. area and firewall. I built a Patriot a couple of years ago, and sold it when I got a real good offer for it. I want to try something quicker, with a lot less work and investment involved. Been building and flying since '74, so I know about keeping it light and tight, and we don't have any pylons to bank and yank around, so I plan on taking it fairly easy with the G's. I'm looking for something that'll be a step up (speed wise) from my Dago Red that I can just have fun with and not worry about too much.


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RE: Viper assembly tips? - 10/24/2004 5:29:59 PM   
daven



Posts: 7026
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		Ed,

I run Carbon Fiber under the skin on all of my quickees, with no spar and very little fiberglass (1 layer of 2 oz, 8" at TE and 15" at LE on the bottom only).

Far from useless if done properly.

Never had a wing fold yet, and have had ready to fly wings at 15 oz.

And yes, these have all been 428 powered planes. You may be overbuilding your wings Ed. Especially if you are completely fiberglassing and painting your wings.

The .52 you plan on using, even if piped, will not be as fast as a Nelson powered Viper. I've seen quite a few handle the nelson, so if you look it over good, you should be in good shape.

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RE: Viper assembly tips? - 10/24/2004 9:04:21 PM   
Ed Smith


 

Posts: 2875
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: online 		Dave,

There have been more posts than I care to read about the dubious quality of Chinese built ARFs. My post was a caution about exceeding the recommended power source for one of these, that is all.

Your advice seems to be "do not worry about it, just look it over" I am sure the AMA will be comforted knowing that a V.P. for the racing S.I.G has that attitude towards safety.

Ed S

(in reply to daven)
       Post #: 7

RE: Viper assembly tips? - 10/24/2004 10:17:17 PM   
daven



Posts: 7026
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		Ed, from what I have seen, the Viper wing is of much better quality and strength than the Lanier wings (albeit at a significant weight gain). If he had been talking about the Lanier wing, I would have given different advice (as in not using a Nelson or Jett). I see no reason why the stock viper wing can't handle 428 engines, or a Piped Magnum .52 for that matter. We've had quite a few of them flown locally with no folds that I am aware of.

I have been one of the minority locally who has asked that stock Predator wings not be flown in 428, but I have seen no reason why the stock viper wing can't hold up. I would change the wing bolts to nylon as I stated above, not for shear, but because I've seen too many metal bolts loosen in flight under vibration.

As to being V.P. of district #5k, as far as I know the election is not over, or have I been appointed to this position.

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RE: Viper assembly tips? - 10/24/2004 10:18:15 PM   
garys


 

Posts: 782
Joined: 1/31/2002
From: San Diego, CA, USA
Status: offline 		The Vipers I've seen have all had very strong wings, unlike the Preditors. I wouldn't worry about a wing failure on a Viper. I think Dave pretty much hit the Viper weak points (wheels, firewall, wing/tail bolts, incidences). If this thread was referring to a Preditor, I would definately say to reinforce the wing for anything more than a 424 level engine.
GS

(in reply to Ed Smith)
       Post #: 9

RE: Viper assembly tips? - 10/26/2004 7:20:30 PM   
NitroWoman



Posts: 327
Joined: 6/30/2002
From: Venus, USA
Status: offline 		My Viper had a few problems. The original wing out of the box did not have the fiberglass over the wing joint properly epoxied. Had to send it back to Tower for replacemant, no problem there. Replacment wing OK. Used a Jett tank and had to move the aileron servo back 1" to clear. Flew with a Rossi Q-500 .40, not as fast as a Nelson but still fun. On my last landing I hit the weeds on the end of our field (these things don't want to slow down). It wasn't going very fast and it hit fairly gently and flipped over on it's back. I didn't think there would be any damage. I was wrong. Fuse broke in half just behind the radio hatch and the firewall was loose, just being held on by the glass, I couldn't detect any pins. I have landed my Predator much harder than this with no damage. Sure glad the Rossi didn't come loose when I was standing in front of it. The machine screw wing hold downs were no problem and never came loose. The plane is easily fixable but there is going to be a weight penalty. Reinforce the rear fuse and the firewall during construction and save yourself some grief.

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RE: Viper assembly tips? - 10/26/2004 8:26:32 PM   
Ed Smith


 

Posts: 2875
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: online 		Dave,

I hope you read the previous post. Imagine a tuned pipe .52 on that one! I rest my case.

Ed S

(in reply to NitroWoman)
       Post #: 11

RE: Viper assembly tips? - 10/27/2004 3:25:00 PM   
Stand



Posts: 94
Joined: 1/1/2003
From: Austin, TX, USA
Status: offline 		There have been several posts here on mods for the Viper and Predator. I found one by Paul Herman:
http://www.rcuniverse.com/forum/m_1213413/anchors_1213413/mpage_1/key_viper+AND+modification/anchor/tm.htm#1213413

There is also a write up at Darrol Cady's web site:
http://www.darrolcady.com/./Racing_Info/racing_info.html

Check the "Predator/Viper ARF modifications"
Stan

< Message edited by Stand -- 10/27/2004 3:26:46 PM >

(in reply to Ed Smith)
       Post #: 12

RE: Viper assembly tips? - 10/28/2004 4:45:23 PM   
John Z Williams Jr


 

Posts: 121
Joined: 9/17/2003
From: Boulder, CO, USA
Status: offline 		Ed states,

"A piece of carbon fibre that lays under the skin, that is useless"????
Hmmm, I know many of the Revlutions had just that, the only spar in the wing was the strip of carbon fibre, there have been many many, many revlutions out there that hold up just great with the useless carbon strip....
I would make sure I know what I am talking about when I make such a definitive statement...

PS There are other custom quickees that I know the builders have taken this strip of uselesss carbon and lay it up under the skins, they too have held up to the forces of 428 for over 5 years now!!!!

I think Dave is correct, you probably have you're wing way over-built....

Just my opinion, well sort of...
JZW

< Message edited by John Z Williams Jr -- 10/28/2004 4:46:43 PM >

(in reply to Ed Smith)
       Post #: 13

RE: Viper assembly tips? - 10/28/2004 4:58:35 PM   
John Z Williams Jr


 

Posts: 121
Joined: 9/17/2003
From: Boulder, CO, USA
Status: offline 		Ed, you rest you're case because a plane flipped over on landing and broke the fuse???
You rest you're case because the wing did not have glass on the center section???
As stated by Dave and others, you do have to look these arf planes over well before you fly them, geeze, I have had professional kits need more work than the stated bad arfs... There is no substitute for a good "Overview" this includes everything... That means all the suspect areas of wing hold blocks, firewall, pinned? not pinned? what is it.. after all the known problem areas of any plane, then look at everything else to make sure the plane is in the best possible condition to withstand the forces of flight and landing...
Just me thoughts,
JZW

(in reply to Ed Smith)
       Post #: 14