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        OK - gonna try the Cox Viper one more time....

#1 Steve McBride Mar 04, 2001 07:34 PM

OK - gonna try the Cox Viper one more time....
Picked one of the little foam free-flight midels from Wal-Mart. This is the one that looks P-51ish. My first attempt some time ago was less than a success http://www.ezonemag.com/disc/frown.gif

This time I am attempting to keep the weight to a minimum. I have toyed with a GWS DX motor taken from the gearbox on the stock prop. On 6 of the little cells that come inside the Viper it pulls pretty good on the stock prop. No current measurements but the motor stays cool even afer long static runs. Depending on current measurements I may go to 7 or 8 cells.

Plans are to use feather receiver and CS-10 sub micro servos. My question is to run ailerons and elevator or rudder elevator? The stock wing has a good deal of dihedral in it so I think rudder flight would be acceptable. If I went with an aileron setup, how about just on one wing?

Any body have any comments or suggestions before I get much farther?

Thanks all!!


#2 winans Mar 05, 2001 09:35 AM


I built the sister to that ship, a Spitfire of the same size. It was one that has not made it to market yet, maybe someday. Anyway, I used a direct drive 130 series motor (same size as stock motor but better quality and much better wind) on 5x110 pack. Used 2 cs-10 size servos, an Alpex rcvr, Jeti 04 esc, rudder/elev controls, stock prop (same as Mustang). Flys like a champ. It's quick but not overly twitchy. I don't recall overall weight, but you can estimate from the hardware choice. My flight times were low, about 2 min, but a better mtor choice would overcome that. I had much more power than really needed. Have fun converting the Mustang.


[This message has been edited by winans (edited 03-05-2001).]

#3 Steve McBride Mar 05, 2001 09:43 AM


Thanks for the information. I'll have to trade a bit of weigt in the form of batteries to use the GWS motor, but I know on 6 cells it is not pulling a lot of current.

I'll stick with rudder/elevator for this time around. Maybe a built-up wing with a bit more area if things go well.

Hey - good idea switching to a screw on spinner cap! The old style would last one landing. At least with these I can remove the cap and drill the prop and re-install without glue http://www.ezonemag.com/disc/smile.gif


#4 bruff Mar 05, 2001 01:16 PM

I have had better luck with the GWS receiver vs the feather. A lot less glitching. Good Luck!

#5 Steve McBride Mar 05, 2001 01:22 PM

Yeah, I was getting glitching even with the antenna extended and about 2 feet away with no servos! I may get one of the GWS servo/receiver/battery/ESC packs if my local hobby shop will ever get channel 34 in!

I just ordered an R700 which brings my total receiver count to 3 - not bad for 6-10 airplanes! I am in serious need of more receivers (and more model memory in my transmitter).

Thanks for the help!


#6 mumboender Mar 05, 2001 04:15 PM

I bought a gws receiver on Channel 38 from Balsapr.com. It came in 3 days and total cost was 32.00. Can't beat that deal. I use it in my E-LMH Helicopter and it is rock solid despite less than a less than ideal location right between the speed control and motor.

#7 jrice Mar 05, 2001 09:03 PM

How much are your planes weighing out to?

I have all of the pieces ready to assemble, but I am waiting for a GWS crystal for my freq. from my LHS.

All togeather with a 4x270 pack, 05 BEC, small motor out of my parts collection, GWS rec. w/ 2 pico gws servos and stock Viper kit, I come out to just over 5oz.

I was thinking of going to 1 servo and having a little up elevator and controlling the altitude with throttle like the Firebird does. Anyone do this? Is it worth the weight savings?

How good do these things fly? Is it worth the effort?

#8 frankenfoamy Mar 06, 2001 01:39 PM

Put a video on my page Kinda proof it works.
6 cell 50mah
2 Hs-50s
GWS direct drive
Stock prop
109 grams RTF
Article coming soon. http://phreak.mine.nu/drblott/RadioControlProjects.htm

[This message has been edited by frankenfoamy (edited 03-06-2001).]

#9 Steve McBride Mar 06, 2001 02:33 PM

Thanks for the Video. Can you comment on how it flew and weather or not it could take a bit more weight (higher capacity battery)?

Thanks a bunch!


#10 Steve McBride Mar 09, 2001 08:02 AM

OK - have the rudder and elevator hinged and the control horns installed (donor parts from an old LiteStik). The motor and prop are installed in one half of the fuse with probond. This allows the fuselage halves to be easily seperated for changes.

I also have an 8 cell pack built up and static runs the GWS motor just gets warm - not hot, so I can't believe the current is very high. I still intend to measure it one day http://www.ezonemag.com/disc/smile.gif

I will keep the stock switch and charge receptacle. I simply removed the battery that was attached to the circuit board and will re-attach the battery pack wires and ESC wires to it. It will remain functional - switch in one direction and it can be charged - switch in the other direction and the ESC and receiver are powered.

The servos go in this weekend - CS-10BB. I plan to mount them inside the tail with only the tip of the control arm protruding for R/E control.

I'll add a bit of tape to the bottom of the wing to keep the flex down as it's going to be a littl mor loaded than the designers intended. I'm pretty optimistic about this one though....if my feather receiver does not glitch on me.

If the weather holds out I will do my test flights on Sunday or early next week.

Thanks for all the info so far!


#11 frankenfoamy May 16, 2001 04:18 PM


Originally posted by stevem:
Thanks for the Video. Can you comment on how it flew and weather or not it could take a bit more weight (higher capacity battery)?

Thanks a bunch!


I am using a 7 cell pack of double time cells (NiMHd) get about 3 minutes plenty of power. It can handle more wieght with the wing loading requiring faster speeds. I re-enforced the wing.
I may try 5 cells for longer duration.

#12 Steve McBride May 16, 2001 04:23 PM

Yeah, I have sence flown on 8 and now 6 cells with good results. Thanks for the help! 5 cells should work well too in my opinion


#13 miker May 18, 2001 08:26 AM

I was working on another project, when I saw frankenfoamy's article on the Cox Viper conversion at rcmicroflight. Needless to say, I dropped the other project.

I am nearly done with my conversion and my weight is showing 129 grams. Looking at the stated 109 g that frankenfoamy mentioned and I am envious.

Any comments on whether this will fly at 129 g, with 6 cell 50mah? I hate to test this beauty and have my usual first flight results.

Thanks for the article and all the useful information supplied here.

#14 Steve McBride May 18, 2001 08:32 AM


Unsure of the weight of mine, but I flew on 8 150mah cells, feather receiver and CS-10's so it could not have weighed less than yours for sure! I am sure it will fly fine. I have flown mine on 6 cells and it flies about the same except with less climb.

Let us know how it goes!


#15 miker May 21, 2001 08:06 AM

I finished with my modifications on Sunday morning.

GWS direct drive
GWS rx
HS-55 servos - rudder/elavator
stock prop (attached as suggested by Mike B)

I took three battery packs:
9 volt Radio Shack high capacity Nicad.
6x50 cell pack
6x110 cell pack

I lightened up the 9 volt by removing the metal casing, which was good for more than 5 grams, but when I did a test run on the motor, I found no power.

For my test flight, I tried the 6x110 cell pack. I threw the plane with full throttle and it spiraled down and hit hard, cracking the body just behind the wing. A little foam CA glue fixed that.

It was pretty clear that weight was a problem, so I switched to the 6x50 pack. This was better, but the plane still did not seem to have enough thrust for its weight.

I am going to checkout my speed control and cells to see if there is anything wrong here. I will report back.

Otherwise, I can't figure out how this can fly on 6 cells. Perhaps at 109 grams this thrust is enough. At 129 my viper is an aerodynamic brick.

Question for Frankenfoamy: How did you get 109 grams? Using the HS-50 instead of HS-55 will save me maybe 6 grams total. What else can I do? My only other thoughts are to trim every electrical wire in the plane to bare minimum length and to lighten the control rods, but I can't imagine that that is worth another 14 grams.

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