green river rc

My Feedback: (2)

My son won it new at a swap meet last weekend. It's suppose to do all kinds of AMA stunts but we couldn't even squeeze a loop out of it. Maybe we are doing something wrong? We are only semi-experienced CL flyers but this is not what we are use to.

The main problem was that we couldn't keep the lines (35' dycron) tight enough. If it got up more than 20 or 30 deg. elevation, the lines went limp and I had to step back to save it and sometimes it would crash, luckily it won't go fast enough to break it. We also tried .008"X35' cables but it would have no such thing, they were to heavy! They recommended other props for better performance, will they make they much difference? Extra wing tip weight didn't help either, any suggestions?

Clean

Use 14 pound test Fusion Syder Wire, this is the knit type wire, not monofilement and is available at Kmart and Walmart in the fishing section. Lighter, cheaper to replace than cable and less draggy than the white stuff. The engine in the Viper is the cause of your problems, it needs an upgrade. Take it off, take it apart and start working. First, reset the ball on the piston, mine was loose from the get go, tighten it up and you have more power. There is not supposed to be much difference in power between the two slit exhaust and the open exhaust, but if you have a cylinder that is open and has the two port feed, swap it. I've heard someone knows how to pop those slits open, but I can't see me doing it successfully. There is a post over on Stuka by Larry Fernandez http://www.clstunt.com/htdocs/dcforu...ID1/13027.html and he has taken the backplate off the motor, modified it and JB welded it into the back of a Norvel engine, then mounted that sucker into the Viper. More power than you'll ever need that way. I have swapped out a Blackwidow base with TeeDee .051 piston/cyl assembly and bored the mount breather hole for better flow, it screams pretty good but now I get fuel foaming problems from the tank, will switch to a balloon tank to get rid of those problems. When it has power, the viper flies fairly well, but you have to work the engines over for it.

dennis

My Feedback: (90)

Throw the motor away and get a Norvel 061 and a texas timer backplate mount that you replace the Norvel backplate with. This is an easy conversion and is easily installed onto the Hyper viper without butchering the whole front up. It would be nicer if you had a pre revlite Norvel as the cylinder isn't so large around. Reduce the angle cut on the plastic tank to about 30 degrees or fit a sloghtly bigger on in. I use a bladder on mine. I know that that motor is going to run at top end till the fuel is gone.
The Norvel 061 is light years ahead in power without having to do diddly to it, compared to the slag Cox motor that they sell you

green river rc

My Feedback: (2)

Yea, that Texas mount is a nifty looking mount, I would hate to spend a dime on a Cox plane. I do have a new Norvel .061 though, might try the other thing.

So I guess the Cox .049 aint gona happen? I didn't think so, how dare them to sell a plane with such bold claims as flying the AMA pattern, and wont even loop. Sometimes I wish Norvel would buy them out, bulldoze the factory and plant it in corn!

Bill Rademacher

My Feedback: (77)

Hi Dave,

I had the same problem. It wouldn't loop very well, and we had intermittent runs on the motor.

Fine a large port cox cylinder, for one thing. I may have on I'll give you. I'll check.

After you get the motor running, it will loop, etc. but a norvell is probably the way to go in the long run. I don't know why they ported these motors down, other than it makes them quieter.

Also, try 20- 25% nitro. It seems to work the best. 35% is too much for this particular motor. It will sieze up temporarily. It's kind of funny.

Hope this helps.

Bill R.

kdheath

Couple of easy things you can do include drilling out the venturi as much as possible. I'll have to look and see if I can find the size it will tolerate again, but the info is out there. Then find a dual port (TeeDee) piston/cylinder set. Try smaller props like a 5/3. A balloon tank is probably the best choice for consistent running. And be sure the piston ball socket is snug. Use a reset tool if it isn't free of slack. Still won't be as good as a Norvel, but much better.

Edit: I thought I could find it. Here's bunch of good stuff about the HV.

http://www.clstunt.com/htdocs/dcforu...ID1/11216.html

Clean

By the way, Cox/Estes is selling the product engines along with thier glow plugs which are pretty cheap at 4.99. You can go to the website and find the link.

I still think they're overpriced, but it's the cheapest price on the glow heads I've seen for quite a while.

gcb

Bear in mind that the larger the intake the less the fuel draw. Of course you can run a baloon tank for pressure.

I do not yet have my new ones, but one from the Nabu Fighters already has two port transfer, including the boost port found in the TD. It has the two slit exhaust ports with no sub-piston induction.

I would also suggest 25% nitro, various props (perhaps a 6x2 might be good for that plane), vayious quantities of head shims, especially if trying the TD (fluted?) head. I think Cox still makes two other heads, the conical (standard), and high-performance (smaller cone with squish band). You may also want to try the Norvel head/plug and the Galbreath head/Nelson plug.
That's a lot of testing for an RTF, but some of it will probably make your Viper Hyper.

George

green river rc

My Feedback: (2)

I may try the Norvel .061 that I already have, all those mods sound costly.

gcb

gr,

Bottom line is that many have been successfully flying the HV. I would suggest a search for any mods.
Things to do that are not costly:
Make sure you are using 25% nitro fuel with 20% oil, mostly castor.
Break-in the engine.
Try different props.
Try a high-performance glow plug...or the one from your Norvel.
Try varying the number of glow plug gaskets (shims).
Check the tank for proper fuel flow. Some Hyper Viper tanks were defective.
I would suggest the steel lines.

Good luck,
George

gcb

green river rc,

There was a discussion on the Hyper Viper at SSW on 3/6. Apparently they are still having problems with the HV tanks. You can contact Cox and they will send you a replacement.
They seem to fly OK with the supplied engine once the tank is replaced.
If you decide to go with the Norvel .061, that should REALLY make it Hyper.

George

green river rc

My Feedback: (2)

I wonder what is wrong with the tanks? It would be great if we could use the supplied engine and save my Norvel for a real plane. ("real" as in balsa) I'll look them up this weekend.

gcb

I think I read that the problem is caused by assembly glue blocking the line, but that may be wrong.
Some good planes for your Norvel might be some of the Dick Sarpolus sheet wing profiles that were originally powered by TeeDee .049's. Flying Models has an online list, I think.
Another possibility would be any of the Golden State 1/2A planes with built-up wing and profile fuselage.
Also, the Brodak 1/2A Flite Streak would be good. I think most of the other Brodak 1/2A's are for Bee type engines.
I build about 1/2 kits and 1/2 from plans.

George

Aeromaniacs

Wing is warped! I had to glue a trim tab on the outboard wing on mine, to get it to fly level. Look to see if the outboard wing is high or low.

Add more tip weight. Put the leadout wire on the last 2 hole. Make sure the leadouts are a little behind the C.G. Mine was actually ahead.

Video of stock Hyper Viper does some basic manuevers on my web page: www.aeromaniacs.com

tylerman

I had a cox Hyper Viper and it hardly had enough power to get off the ground--So i got bored and tore off the plastic fuse and i kept the styrofoam wing. I built a profile fuse out of balsa and made a nice beefy motor mount, i also cut off the plastic tail feathers and found a way to mount that on and work. I painted everything one color and I took out the fuel tank and i got a Cox .049 black widow. All in all it took about 4 hours but when i flew it, it was a whole new plane-- All i can say is wow

Thats just what i did.
If you dont want to go through all that work then go ahead and buy a bigger motor just make sure you put washers on one side of the motor to angle it out. This plane has a tendancy to let the lines go slack.

mclintock

My Feedback: (3)

Wow, I've got a pt-19 with the same product engine and it will loop fine! I'm cheating though- using the ten pound test spider wire fishing lines... I went nuts and tried using 60 foot lines and that was a bad idea- but really funny to try!
It flew fine, but I had to keep moving my feet to get so the plane wasn't flying twoards me with all the bow in the lines! Don't use that 10 pound line, it's too weak- broke one on takeoff and had to wait out the tank with the plane doing real high circles above me...

A 6-4 prop is mandatory for really getting the plastic rtf cox to fly right, also at least 25percent nitro.

Old Sourdough

I'm sorry to be so late responding to this topic, but because of the graphics here, the site takes a long time to load on the dial up connection.

There are three HyperVipers flying here. All fly very well using the stock engine and prop! We use .008" x 35' steel lines and Byron's 1/2A fuel (25% nitro, 205 all castor lube). The key is to follow the recommended break in procedure of three tanks on the ground, starting off rich and then leaning the engine in short bursts to break in the engine. All three of us run a click or two below all out lean for flying purposes. The planes take off grass well, but can sometimes get hung up in landing and flip over. We've had no crashes.

We did notice that the original tanks that arrived in the boxes did not allow the fuel to flow freely. We checked before installing them by blowing through one vent while blocking the other and checking the amount of air exiting the fuel feed tube. We advised Cox (Estes) and they sent us new ones with no question or charge. Since then, everything's been the cat's meow!

This is a great flying little plane for the $40.00 for which they can now be bought. Most of the initial buyers who complained about performance assembled the plane and went flying without the break in process. Our experience disagrees with theirs.

oldgit1

if you dont break in the engine as instuctions , is the engine ruined or will it just smooth out after a few flights ,

Old Sourdough

If you haven't overheated the engine badly by using a fuel with too little lubricant, you should be able to break in the engine as the directions tell you. That should solve the problems a lot of folks have been having, although we have found that the run does continue to improve with further running while flying.

One modification we did make was to add a nickel to the weight spot on the lower side of the outboard wing. We haven't had any problems with line tension in winds under fifteen miles an hour. Cox used to say that if one could see the leaves moving on trees, the wind was not too strong to fly their 1/2A models. However, if one could see the even the smaller branches to which those leaves were attached, there was too much wind to fly them. This latter condition is far less wind than the fifteen miles an hour we set as a maximum for the Hyper Viper.

The plane is just a flat ball to fly!

oldgit1

thaks for the info .
i have a norvel engine ,the one with the tank on the rear of it . i have a texas timer backplate comming for it so i might see if i can convert it to the norvel ..that should liven it up a bit dont you think , has anyone here ever done this to a hyper viper . and is it easy enough ..
looks like it would have to be cylinder upright as it has a muffler so that would be at the side .and i think i would have to put some tube on the muffler so as to drip oil away from the bulkhead ..
would be good if someone has done this to let me know .do you think i could still use the same fuel tank that comes with the hyper

Old Sourdough

I may be a real wimp, but I find that the Hyper Viper as shipped, when assembled and broken in per the directions (We do read and follow those, don't we?), has more than enough power and speed both for here and in the higher altitudes of Reno, NV. It does the maneuvers of which I'm capable and then some. Why are folks so eager to modify unfamiliar models without first making them work to their capabilities?

As it's your model, you can change the engine if you like, but I'm not certain that any benefit in doing so would outweigh the detriments, such as changing balance, cutting up a nice plane, higher fuel consumption, etc.

oldgit1

well , i agree , i will try to get the stock setup to work first ,but if it dont go , then here comes the norvel .
did you use the stock prop that came with the kit as well ?

Old Sourdough

I am still using the original prop that came in the box. I haven't yet tried them, but I did obtain several of the Cox recommended APC props to use in the event the original didn't work out. I bought them as a result of the hysteria created by a couple of early users of the plane who had nothing but complaints about its capabilities and lack of power. It was later discovered that they had assembled the kit, fueled it up and flew it (and in attempting maneuvering flight, crashed it) without even running the engine for the slightest break in period prior to flight, contrary to the Cox instructions.

What engine does any of us own that does not require at least a nominal break in period prior to testing its full capabilities? I have yet to own any, if they exist!

oldgit1

yes i would say i was guilty of not running in the engine , i ran it for about three mins in my garden before the people around me started giving me that look about the noise ,,[>:] so i thought ok , i will take it to the park and fly run it in ,, but no go[]
it would not even take off ,,my wife launched it and it just went straight down , not enough power to pull itself .
i am unsure from that it could improve that much , but will give it a go ..
also after reading threads here i put a 6x4 prop on without trying the stock one ,,
tought me a lesson
anyway i will get three tankfulls of fuel through before i try to fly it again ,,
just one more thing did you use the stock lines as well ,as they do seem rather heavy , ?
regards .,.,cliff

Old Sourdough

Again, I apologize for the time it took to post this reply, but I don't come here often. We are still using the supplied dacron lines, but all of us have .008"x35' lines with which to replace those. We will be doing this soon as the dacron lines are getting a bit oil-soaked and dirty. They are starting to stick a bit as a result. We anticipate even better performance after making that change.