shussey

Hi all,

I wanted to share something that just happened to me before dinner. I just got an OS 91 from a guy in my club to put on my Sig 4* sixty. It hadn't been run in a while so I decided to bench run it to tune it and get it ready to put on my plane.

So I strapped it to my homemade test stand and hand flipped it several times. After a few spurts and sputters it started. I had the throttle about 1/3 open and it ran fine for a minute or so....then it happened. The darn thing started coming out of my test stand...As it was working its way free, I grabbed the throttle and tried to get it backed down a little. Luckily, I was marginally successful. While backing down the throttle I grabbed the needle valve to try to hold it and with such a small "handle" it didn't take long for it to get free and go shooting across my garage. Wow!!!! If you've never seen an OS 91 "flying" across your garage, you haven't lived.

Luckily, I was able to steer the engine into the other wall and away from the cars so the only thing that was damaged was a Coleman cooler - the prop took a small chunk out of the side of it, my brand new prop - shattered, my glow starter - exploded on impact, but is fixable and the rocker cover that was cracked on impact with the cooler.

After seeing it all happen so quickly I realized how lucky I had been. That flying hunk of metal could have done some serious damange to me, my kids had they been out there or anyone else around.

So, be careful with these larger engines on test stands....apparently my test stand design didn't work like it should have on the 91. It has worked for months on my 46 and 61 2 strokes. I guess the "more torque" in a 4 stroke is true.

If anyone knows where I can get a real test stand and a rocker cover for an OS 91...please let me know. In the future, I'm going to rig a secondary security device (a tie-down strap) screwed into my work bench to avoid the flying engine again.

Excuse me while I go change my shorts!!!

TimC

Whoa, a close one shussey! I did the same thing with a 1.60 Gemini. I had it lag bolted into the end of a not so sound 6x6. It ripped out and flew right into the ground. The 17" prop and an exhaust pipe were the only casualties. J-Tec makes a dandy test stand. Maybe Tower will have the valve cover. Is it the Surpass II model? Anyway, semi-good save on getting the throttle shut down.
Edited to change "E" to Surpass II.

shag555

That's nothing... My Wife wrecks in the garage all the time!!!

MPB

mimhoff

My Feedback: (3)

shussey--

Here is a very nice test stand that will pretty much handle anything up to a 150cc gas with optional adaptor. I don't own one yet -- but it is on my must have list


http://www.pspmfg.com/EngineTestStand.html

kregan

A freind of mine has that test stand and I have used it a couple
of times, once on a 1.20 4 stroke and another time with a 1.50
Saito... It is really nice.

rcbif

something like this happened in my room with a fighterbird prop. I made a small air boat and was showing my friend how much it put out, but I forgot it was a pusher so after I hooked it straight up to the battery I noticed the air was blowing toward me, then snap, prop shot off the shaft over my friends shoulder into my traxxas stampede. It put a good 1cm cut on the bumper portion of the body and a hudge dent in the plastic prop. That body could have been my friends neck or shoulder[:@], so I'm VERY careful with that kinda stuff now

Kmot

My Feedback: (24)

The PSP stand is worth every penny. I have run a Saito 120 on it and it is solid as an I-beam.

GeneG

My Feedback: (11)

I'll second (or third) the the thumbs up for the PSP Engine stand. I got it with the mounting post. Followed the directions and quick-cemented it into the ground. I can run a DA-50 on it all day and it does not budge! Of course, if I move, the post is staying with the house!

I can't recommend this unit highly enough. It is the best buy for the money.

Semi Retired Aviator

Happened to me about thirty years ago when I was much younger and much less smart....obviously.

I 'mounted' a Taipan 2.5 cc diesel in a vice using one of the mounting lugs, ie., the lug was cramped in the vice and the engine was on its side.

It fired up and took off...flew about 30 feet and hit a wall. No injuries.

rcflyer52

My Feedback: (7)

FOR ME, IT IS A WHOLE LOT EASIER TO JUST MOUNT IT ON THE AIRPLANE. THEN YOU HAVE SOMETHING BIG TO HOLD ON TO & YOU HAVE CONTROL OF THE THROTTLE. THAT'S HOW I BREAK IN ALL MY ENGINES NOW.

flyin_kid

Same for me... Its a lot easier and you get to fly with the price of the gas .... ive heard of a lot of accidents with test stands... one of my buddys went to get somthing on the other side of the room, and the motor started shakin in the test stand and it rattled itself loose and took off and landed right in the middle of his stomach.... talk about a big bruse... he got lucky it hit him dead center so the spinner hit him and the prop didnt get the first hit.... i would say he got off really luckey with about a softball size bruse and nothing else [&:]

CHassan

My Feedback: (13)

lol I have an old junk table I bolted a make shift mount to. This way I can move the table out in the driveway and not fill my garage will smoke. Well it worked fine on a .40 engine, then when I went to run a Saito twin .90, I found my table would slide across the driveway. Luckily at no great speed, but now I set a cinder block on top of it and put it in the grass.

MinnFlyer

My Feedback: (4)

The way I see it, if the engine is going into a 4*60, why not just install it and test it there?

grim21

I learned this lesson the hardway. Last summer I got bit by my prop when (it turns out) the throttle linkage disconnected on my U Can Do and it went full throttle on startup. I had to reach over the prop to grab the fuse to hold it. That's when I got bit! Ever since them I keep a rag with me so I can toss it into the prop in an emergency. A T shirt works good on a Saito .82. Just wanted to pass on a tip I found very helpful.

GeneG

My Feedback: (11)

Breaking in a motor on a plane is not always a good idea. If the engine is a small 2 stroke I don't think it really matters. It's a different story with 4 strokers in the .90+ range. The first couple of tanks through it cause the airframe to vibrate so badly that you stand a good chance of breaking something on the airframe. As far as I'm concerned all my hard work if worth protecting with an engine stand. Stands also put the engine at a height that is easier to work on.

If you going to use a stand just don't get a cheap one. Unless your a machinist, for gods sake don't make one yourself!

Once I started breaking engines in on a stand I never thought of doing it another way.

Jeffpro

My Feedback: (1)

This test stand works pretty well for me:

[link=http://wintellect.com/weblogs//images/wintellect_com/wintellect/3/o_Model%20of%20the%20Month.jpg]http://wintellect.com/weblogs//images/wintellect_com/wintellect/3/o_Model%20of%20the%20Month.jpg[/link]

With that big Saito 220 on the nose, the stand can almost double as an airplane, too. :-)

Last year we had a pretty bad accident in our club involving a test stand. A member was breaking in an engine and only had two bolts holding it to the stand. One of the bolts vibrated loose. The engine spun around the remaining bolt and hit the guy running the engine. A dozen stitches took care of the gash in his arm.

D Bronk

BOLT HOLEs are put in various things, for a reason,NOT just for convenience.PRETTY harsh way to learn.

fredscz

My Feedback: (47)

While I have a nice metal break-in stand that is bolted to a 2x6 that I attach to a work-mate bench so that it is portable, I also have used a piece of 3/4 or 1/2 inch plywood with a notch cut in it to fit the engine. Another one I have used is a metal engine mount that comes with some arf's and has a clamp hold down arrangement to hold the engine. I bolt this to a two-by and then to the work mate and has worked fine. One of the fold up metal saw-horses would work good too instead of a work-mate.. The arf metal mounts can be found cheap at the swap meets normally.
FEB