PylonWorld

We've already heard one report of a plane crashing due to the metal wing bolts backing out. Another person reported his loose after every flight.

I have to admit, I've been lazy on this and have simply been putting electrical tape across the front bolts and another strip across the rear bolts.

Today when I started up, I wanted to tach the engine to make sure it's not over 16,500 because it will be checked at a race I'm attending on the 27th.

In less than 30 seconds, THE RIGHT FRONT BOLT BACKED OUT 3/4".

I had forgotten to tape the bolts.

This is a SERIOUS issue, in my opinion, and everyone needs to be diligent in making sure it doesn't lead to lost planes, or much worse.

John Z Williams Jr

I am suprised to hear people having trouble with metal bolts, that is one of the first things I learned when flying thunder-tiger 424 class years ago, it was common knowlege that metal bolts would vibrate out. We always used nylon 1/4-20 for that reason. I would think anyone flying quickee 500 with any experience would be aware of that fact, I would hope anyone getting into flying quickee 500 would get some advise about what to look for and what not to look for when preparing a racer. Things like beefing up firewall and wing hold down blocks, toothpick the fire wall and wing hold down blocks and landing gear block are just some of the basics done to all quickees, made of wood, and should be passed on to new racers by experienced ones....
Just some thoughts on it.... No offense intened, John

PylonWorld

The Viper 500 ARF is generally well built.

However, it has 8-32 blind mounting nuts in the wing hold down blocks. And they supply 8-32 flat head steel screws for holding the wing down.

We are getting more and more newcomers to pylon, or at least pylon type planes. And it is great that they getting into it. Many of these people may not have experienced pylon racers to help them prep a plane. And the Viper 500 is such an easy ARF to assemble that they can do it themselves. If you can put any ARF trainer together, you can put a Viper together per the instructions.

Hopefully Great Planes will fix this in the next revision.

The only reason I used the supplied bolts was because the plane was supposedly well tested. And the 8-32 blind nut size does not allow you to just take them out and re-tap for 1/4-20. You either have to: plug the hole, re-drill, and tap ... replace the 8-32 blind nuts with 1/4-20 blind nuts ... or put a peice of hardwood where the blind nut resided (and possibly still plug the hole).

You are correct ... almost anybody in racing knows that most racers use 1/4-20 nylon bolts, myself included. In fact, I got my Viper 500 on a Thursday afternoon, and the following Monday I was on the phone with the designer discussing the danger of the metal bolts.

I think we need to be VERY proactive in advising club mates, friends, etc to the danger of the metal bolts. That's why I pinned this warning message to the top of this forum.

Lefty-RCU

Simply drill out the holes in the wing saddles w/5/16" drill and press in from the bottom 1/4X20 blind nuts. Use 1/4X20 nylon flat head screws and the problem is solved.

GFTL


Bryant

Zeroman

I found what works well is some Locktite.It will gum up the threads so you can reuse several times.Chris.

DMyer

My Feedback: (2)

I hope you are using "BLUE" Locktite!

One question for Don. You said they are checking the tach readings to assure they don't go over 16,500.... what do people do that are blessed with a good TT 40 Pro that exceeds that limit(not too uncommon)? Do you:

A) - Back out the needle
B) - Throttle back
C) - Add a set amount of weight per each 100 RPM over 16,500
D) - Switch it with the Novice's engine
E) - Attach streamer to rear


Just curious since we don't check RPM's here in the east.

PylonWorld

I don't know what they do.

I'm a dealer for www.KangkeUsa.com and I can get the Tiger Shark engines for a discount. So I had bought some .40's to use for a trainer for my son, testing to see if they could be used for 424, etc. Mine are the red head edition ... they have since changed to an unanodized head.

They don't have the same backplate dimensions as the OS .40/.46 FX, TT Pro .40, JETT, Nelson, etc, and I had made up one mount so that I could use one for 424. But they work just fine on the universal Viper mount (so far).

I talked to Mac at [link=http://www.hodgeshobbies.com]Hodges Hobbies[/link] outside of Atlanta, and he said that they are running 424 "by the book" and even though most people are running the TT Pro .40, we can run anything we want as long as it's not over 16,500.

If the TT Pro .40 guys are over 16,500 I'm not going to complain. I'm just glad to be able to run what I have. We'll have fun, as long as the planes last at least, which is what we're going for.

RC_Junky

My Feedback: (1)

So what would be the best way to convert the Viper 500 metal wing bolts to 1/4 20 nylon?

PylonWorld

As Bryant mentioned above, you can just pop out the blind nuts, drill the holes to fit 1/4-20 blind nuts, and install the blind nuts.

I'm probably going to use a more time consuming method:

* do one hole at a time

* drill out for a 5/16" dowel

* cut a piece of dowel that is 1/4" long

* epoxy a 3/16" thick 5/8"x5/8" piece of maple to the bottom of the hold down plate

* epoxy in the dowel

* drill a new hole sized for a 1/4-20 tap and tap the hole.

There is a possibility that I'll skip plugging the hole and just let the maple do the job. Or I may fill the hole with epoxy and microfibers since that's what I'm going to use to bond the maple to the hold down plate.

There is also a possibility that for 424 that I'm just going to tape the bolts.

Mike Hill and I have put some serious usage on my first Viper with a 424 engine and as long as I really tighten the bolts down, and tape over them, they don't seem to be loosening.

Ed Smith

Sorry Don, I just cannot let this go.

So the secret to keeping the wing screws in is to tighten them up??

Ed S

PylonWorld

Ed,

Since you insisted that they shouldn't be a problem, I started tightening them tighter, even though you can see the skin of the wing deforming a little.

I don't know if it is that they are tighter, or if it is the tape that is keeping them in.

But I do know that your insistance that they should work got me to tighten them tighter, and not worry so much about seeing the sheeting around them on the front bolts especially deforming a little. Like you said, the wing has to deal with a lot of force anyway, so why not tighten them plenty tight?

On another note, I think I made a mistake bringing Mike into pylon racing, because he's certainly going to be kicking some butt, especially mine. Actually it's great because I'm teaching him about fiberglass and composite construction, and during his work breaks we go out to my field and practice. He finished laying up the other side of the Hughes H-1 mold this week and we popped it off yesterday.

Ed Smith

So your "Apprentice" builds Model Airplanes for a job and between times he gets to fly a free racer on a private course. How is it you did not advertise that position??

Ed S

PylonWorld

Well Ed, it was one of those happy accidents where everything just came together.

He (and his family) are pretty happy about it. Yesterday he called his dad, who also competes in pattern, to come over. Before you know it, Pops has his watch off, timing Mike's laps. His best was an 8.28 for one lap which would translate to a 1:25 or so in 424 on the short course. That's pretty good for somebody who just started pylon this week.

The great thing is that projects are getting finished up, and I don't have to use my "Solo Launch technique".

Plus I'm going to get to learn all of the Pattern and 3D stuff from Mike.

Ed Smith

Don,
If you wish to pylon race do not pollute your mind with the other stuff!

Ed S

PylonWorld

Ed,

After seeing how fast Mike is adapting to pylon, I have to believe that becoming a better pilot in general will help me in pylon.

Since some people think I don't have a chance in the pylon world, I need to have a backup option.

DHG

My Feedback: (7)

1. If racing were easy, Aerobatic types would do it.

DHG

My Feedback: (7)

2. On metal bolts, clevis threads, and any other place you have things loosening under vibration when you don't want them to, look for a product called Vibra-Tite. It's a reddish fluid that you paint on the threads and allow to dry. It makes sort of a rubbery coating that lasts for a long time. Unlike Loctite, it doesn't crack loose and give up after the seal is first broken, but will re-grip even after the bolt starts to turn. I'm told that there is a similar product sold in the U.K. under the name Hylemar or Hilamar (sp?).

MDP

Duane is right about the rubber like stuff you can paint on the threads. That was a treatment we used to use in the machine shop......Has any one thought about precision cross threading, metric bolt with SAE thread, beating the threads on the bolt with a hammer, etc ?....Just kidding !....Precision sheet metal shops have locking blind nuts of various styles that press in. Some have very precision, GH1 to GH5 fit, hardened or soft threads etc. Some feature all metal locking threads that are a little distorted to make them lock, and some simply have nylon locks with metal threads just like the nylon lock nuts. Years ago I tried aluminum 1/4 20 bolts for wing bolts, but soon found they vibrated loose too easily, and were unsafe for high vibration applications. I would not consider using a metal bolt without some sort of vibration protected locking system, but there are many ways to do it.....