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Cox Hyper Viper
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? |
RE: Cox Hyper Viper
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.
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RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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! |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
ORIGINAL: 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. That's a lot of testing for an RTF, but some of it will probably make your Viper Hyper. :) George |
RE: Cox Hyper Viper
I may try the Norvel .061 that I already have, all those mods sound costly.
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RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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.
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RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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 |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
if you dont break in the engine as instuctions , is the engine ruined or will it just smooth out after a few flights ,
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RE: Cox Hyper Viper
ORIGINAL: oldgit1 if you dont break in the engine as instuctions , is the engine ruined or will it just smooth out after a few flights , 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! |
RE: Cox Hyper Viper
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;) |
RE: Cox Hyper Viper
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. |
RE: Cox Hyper Viper
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 ? ;) |
RE: Cox Hyper Viper
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! |
RE: Cox Hyper Viper
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[:o]
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 |
RE: Cox Hyper Viper
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.
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RE: Cox Hyper Viper
The following is reprinted from a comprehensive review and discussion of the HyperViper at another site.
See: [link=http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=show_thread&om=136&forum=DCForumID9 &viewmode=all]HyperViper Early Reports[/link] "I don't know about your atmospheric conditions or altitude, but I will say that the three of us that fly them together here have had only minor problems. The stock plane flies well, with good line tension throughout the flight hemisphere. We are using the stock engines running Byron 1/2a fuel (25% Nitro, 20% all castor, 55%methanol) and using the supplied Cox prop, although we all have several of the Cox recommended APC props to try. The three of us are all using the supplied dacron lines and handles, as well, but all of us have 35'x .008" cables that we'll be using soon, as the dacron is becoming oil soaked and sticky. The only modifications (?) we've made are: 1. Add a Nickel (5ยข) to the weight hole on the bottom of the outboard wing for a bit more tip weight and cover the hole with a piece of 2" wide clear tape. 2. Install the leadouts one hole to the rear of the position suggested in the plans. The other problems we have had are: 1. Two of the three fuel tanks were improperly joined to the point that air would not exit the tank when blowing into the fuel outlet. Cox/Estes replaced the tanks with no problem. We were not the first to have this problem, and we checked the tanks before assembling the planes. 2. One plane lost its canopy on every flight until the owner taped the front to the fuselage. We're going to find some "Goop" to fix that problem permanently. We decided, contrary to the stereotypical male image, to read and follow the directions that came in the box. The only reason we installed the leadouts/lines about 1/16" to the rear of the position indicated in the directions was that one of us already had a HyperViper and had flown it at his winter home in Reno (at a much higher elevation than here) with good results. He found that variance to be worthwhile while flying there. He also discovered the advisability of that Nickel more tip weight at that time. We also broke the engines in a bit, again following the break-in instructions with the plane, by running three tanks on the ground, leaning the mixture on all three runs until the engine would hold a strong, high RPM. None of us are engine gurus or designers, but this process works!! The engines have continued to gain power with additional runs while flying. On none of the flights I've watched or flown have I seen any of the problems you and other folks have described. We are not expert level fliers, but we do know a fairly decent airplane when we see or fly one. While I'm certain that the mods done by Larry and others will provide better performance, the plane does pretty well stock. Did you read Larry Renger's review? It's the first post in this thread. In it, he wrote, "...Don't even dream of trying to fly with .012 lines, unless you just want to climb, dive, and fly level I also found that I needed extra tip weight (everyone seems to be finding the same), and it has now been added....." This might be your biggest problem so far. Has your engine been properly broken in? I admire the excellent TD .049 installation shown here as well, but I'm not convinced that it is needed. As far as replacing tail feathers and sealing the bottom of the fuselage with balsa, I would ask, "Why?" If one is going to all that trouble, why not go all the way and throw away everything but that foam wing and possibly the landing gear and build the rest of the plane from appropriately sized balsa. That's what I would do if I wanted the ultimate in performance from that wing. Finally, as I wrote previously, I'm not an expert flyer who would be able to obtain the performance you might be seeking, but for my money ($40.00 at the LHS) the HyperViper is a good machine as it comes from the factory. I have 1/2a planes that I've built that fly much better, as they are larger and much lighter, but when I consider the cost of balsa, finishing materials, tank, engine, wheels and all the other bits required, to say nothing of my time (if I considered it as a cost), those probably cost at least double, if not considerably more, the price of the HyperViper." |
RE: Cox Hyper Viper
i have one of these and not so good. iguess it is for beginers.
but dose anybody know where to get parts for these |
RE: Cox Hyper Viper
Actually all the years I've been flying years back of ucontrol. I flown many stunt planes. But cox hyper is actually more touchy for some reason. And it gets me more dizzy
then my other stunt ucontrol airplanes. There .40 size. But it has longer wire and stuff. I don't know who has parts for cox hyper. But I bet atleast ebay does. Check it out. Also if you want run ur plane with 30-35 percent of trexxas racing fuel. You'll see a huge difference. |
RE: Cox Hyper Viper
For anyone still following this thread....I've got my project "Frankenviper" still underway. I bought an "old-style" Killer Bee...the high-performance version...not the recent renamed Baby-Bees in the hopes that the added performance will cure the woes seemed to be cause by the soemwhat anemic Surestart engines. When I get it flying I'll send a report. One modification I did was to the horizontal stabilizer. The "pinned" arrangement seemed to bind and not move smoothly at all so I removed it and reattached the elevator with good old fashioned cloth hinges....moves smooth as silk now. I am planing on covering the wing with whatever the lightest film I can get is to add some strength...which may push it over the edge power wise but I have a spare wing just in case to try if that doesn't work.
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RE: Cox Hyper Viper
i have a profi .049 installed in mine with bladder pressure still it does not fly as well as it looks.
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RE: Cox Hyper Viper
I have a norvel mounted on a texas timer mount.
flys pretty darn good. It's a beast. billrad |
RE: Cox Hyper Viper
Hi, do you still fly this thing? How did you did you're mod? Got pics of it?
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RE: Cox Hyper Viper
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I bought a hyper viper about two years ago. The engine ran great after about two tanks. It is fast in level flight, but kind of shaky in maneuvers. It's on the wall in the living room now. If past experience with cox planes has taught me anything, it's that they degrade from fuel exposure after a few months of inactivity. I doubt if I will fly it again. I personally think the older super chipmunk was a better out of the box flyer.
I remember at the Lake Charles Nats in the late seventies the Cox people brought an 18 wheeler full of planes and they would let anyone that was interested take a stab at flying them. I've never seen so many crashed planes in one pile in my life! |
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