OS BGX-3500 or ST4500.

ChrisS1642

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Feb 27, 1995, 6:14:18 PM2/27/95

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Does anyone have any experence with a OS BGX-3500 or a Super Tiger
4500. I am currenty looking for a engine for my 1/5 Corsair that will not
protrude out of the collowing.

Peter Ashwood-Smith

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Feb 27, 1995, 9:50:13 PM2/27/95

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In article <3itmca$d...@newsbf02.news.aol.com>,

A general comment: large glow engines are simply not as reliable as
large gas engines. If you look at most 80"+ wingspan planes these days
the vast majority are flying with gas engines. There is a good reason.
Gas engines are FAR more reliable than glow engines. Sure they weigh a
tad more but that weight is more than offset by the weight of the
extra glow fuel you must carry and the weight of the onboard glow system
you will eventually install after your 1st or 2nd dead stick (assuming
the plane survies). You'll need at least 32Oz glow fuel for 8-10 minutes
v.s 24oz for 20 minutes on Gas.

That 1/5 scale Corsair is gonna cost you a couple of grand by the
time you get it airborne and if that little glow engine fails once
in say 20 flights you may get 30 or so flights before you total the
plane. Ask yourself how often your glow engines fail in flight. Even
my most reliable glow engines will typically stop for no apparent
reason once in 40-50 flights. This simply is not reliable enought for
this kind of project. You need an engine that stops only when it
runs out of gas.

A better solution would be a G-62 (a G45 may do depending on the
planes weight). Sure you will have a spark plug sticking out of the
bottom of the cowl but you can remove it for static judging etc.
and put it in before you fly. Or, if you are really stuck on a
ST or BGX you can get a C&H electronic ignition but by then the cost
and weight of the power train is going to be about the same as
a G-62 and cost considerably more. Besides that Corsair of yours
is going to need a fair amount of weight to get the proper CG
so the weight saving is almost certainly irrelivant.

In general glow engines are very susceptable to proper mixture
setting. As the engine and engine compartment heat up the mixture
will change. The mixture affects the heat of the expolsion and
that in turn affects how much risidual heat is left in the glow
plug to fire the next revolution. An air bubble in the gas line
for example will kill a glow engine because the moment it stops
firing its dead, even if it gets gas a fraction of a second later.
Unlike a gas engine which sparks as long as it is spinning and
will usually just hickup its way though the bubble in the gas
line. You could put on board glow and leave it on all the time
but this will drastically shorten the life of the glow plug with
equally dramatic results.

Peter

P.S. (I've travelled this path myself, email me if you want
more details as I don't want to bore the rest of the netters
as they must all know my complaints by heart by now).

Robert H. Klenke

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Feb 28, 1995, 12:36:07 PM2/28/95

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I have an OS BGX-3500 that I had in my Ohio RC Ultimate. The
engine is one of the easiest starting engines I've ever had, bar none.
The problem is, it never kept running. I was using a Davis muffled
pipe on it and even though it was very quiet, it always overheated and
quit. It also used ALOT of fuel in that configuration (24oz in <10
minutes). I have since taken the engine off of the Ultimate and put it
on a Stinger 120 where I run it with the standard muffler and
uncowled. I run it as rich as I can, and it burns less fuel without
the pipe and is much more reliable. It still gets hot when doing alot
of verticle stuff and has quit once or twich on this plane too. What
saves the Stinger is that unlike the Ultimate, it will glide!

I have now experience with the ST4500, but I will never again
buy a glow engine for a lager scale plane. If there is a gas
equivalent for the engine you are looking at, go with that instead.
Even if it means a slight penalty on looks for a cylinder sticking
out. The reliability will be well worth it.

Bob
--
----------------------------------------------------------------------
Bob Klenke, Ph.D., Senior Scientist Dept. of Electrical Engineering
(804) 924-6079 [office] Room E208
(804) 924-4489 [lab] Thornton Hall
(804) 924-8818 [fax] University of Virginia
e-mail: kle...@Virginia.EDU Charlottesville, VA 22903-2442
----------------------------------------------------------------------

propwash

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Mar 2, 1995, 8:34:03 AM3/2/95

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In article <3itmca$d...@newsbf02.news.aol.com>,
chris...@aol.com says...

I have to concur with the replies I have seen so far.
Gas engines are generally more reliable and cheaper to
operate their lifespan. I suggest you consider a G-62 or
equivalent gas engine. I would hope you would choose
reliability over asthetics. I have a 1/5 scale mustang I
am working on and modified the kit to take a gas engine
mounted to the firewall instead of an ST3000 mounted to
maple mounts as the kit was originally designed for.
Sure the engine I choose will probably have the bottom of
the cowl cut away a little bit to accomodate the larger
gas engine but the plane will not crash because of a glow
plug problem or a leaning out problem in flight. Your
1/5 corsair's firewall and cowl have got to be big enough
to swallow a G-62 or Quadra 52 without cutting the cowl
to get the engine to fit. Remember, in real life, the
Corsair's engine was probably the biggest darn engine
ever put on a single seat fighter at the time (hence the
gull wing to give the props ground clearance to swing the
huge 4 blade prop). If a large gas engine will almost
completely fit in my mustang than I would think you would
have an ever better matchup if you kit is even close to
scale.

Aren't airing you questions publicly fun?

Good luck.

Peter Ashwood-Smith

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Mar 2, 1995, 6:04:07 PM3/2/95

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[ good advice deleted (especially since I agree with it) ]

|>
|> Aren't airing you questions publicly fun?
|>
|> Good luck.
|>

This is one heck of an important bit of advice to take Chris.
You've got three folks here all saying the same thing about
big gas engines v.s. the big glow engines. The biggest mistake
I've made in my modelling career so far is putting a glow engine
in a large plane. I'll NEVER make that mistake again. BTW, Zenoah
make engines for ultra lights and homebuilts where reliability
is rather more important than for our models.

Let us know how it goes.

Peter.

P.S. just been out shooting touch and goes on the snow in
about -10C and 15kts winds. Are we Canadians a hardy (fool) bunch
or what! Now if I can just get the feeling back in my little finger
I should be able to hit the return key ......
there ... did it.

ChrisS1642

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Mar 3, 1995, 8:13:14 PM3/3/95

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First of all thanks to everyone who responded, it certainly appears
that the Zenoah is the popular gas engine here.
In case anyone was wondering the Corsair is a Byron kit and of course
most easily users there Purrr'npower muffer mount(combo engine mount and
muffler put together) with a gas engine. It is now avaible tuned to the
Zenoah G-62, the Quadra 52s, or Byrons own Mustang engine.
I know its just out however has anyone tried the new Mustang? I am
tempted to go with the G-62 just because it is a proven design however I
am curious about the others as well. Thanks!

Chris...@aol.com

Randy Brown

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Mar 4, 1995, 2:41:00 PM3/4/95

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R> I have an OS BGX-3500 that I had in my Ohio RC Ultimate. The

Hi Bob, I can't help you with the engine problem, but do you have any
tips on your Ohio RC Ultimate. I have one not built yet, and I am going
to put a 3.2 in it.(gas of coarse).

Have you ever thought about a pump for the OS BGX_3500?

Randy

Randy...@Softnet.com -!-
London Free Aires -------O-------
Forest City Fliers / \
London,Ont.Canada
!!!Real Men Fly Bipes and Pattern Planes!!!

Up...................Up..............Gone
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* CmpQwk #UNREG * UNREGISTERED EVALUATION COPY

Kraig

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Mar 3, 1995, 12:50:59 PM3/3/95

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At the risk of going against the grain, I've flown my O.S. BGX-1 for over
six years in my 80" Laser and finally sold it this winter. I would recommend
looking at the gas burners though.
Kraig

Robert H. Klenke

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Mar 6, 1995, 12:38:20 PM3/6/95

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In article <5.3414.117...@softnet.com>, randy...@softnet.com

The main problem you will have is that when balanced as per the plans
(with a gas engine, it will tend to be nose heavy, even with servos in
the
tail) and the gear placed as per the plans, it will nose over quite
easily,
especially with the tank full. Several people with this plane I saw had
turned the gear around so it raked forward. It solved the problem, but
looked dorky. What I did was put a 1/4" shim between the aft edge of the
gear and the gear mounting plate which angled the gear less toward the
tail
and moved the wheels about 1" farther forward. If I built another one, I
would
move the gear mounting plate 1" forward and do what I did which would
move
the wheels about 2" forward. Its not exactly scale, but big props are
expensive!

|>
|> Have you ever thought about a pump for the OS BGX_3500?

Basically, the problem with the OS in this application was
overheating.
The engine was too tightly cowled, had too restrictive a muffler, and
was
driving too much prop. If I ran the engine VERY rich and never did any
verticals
it would run OK, but it wasn't much fun. The OS runs fine in its new
uncowled
home in the Stinger. and uses much less fuel without the Davis
pipe/muffler.
A 3.2 size gas engine in the Ultimate is the way to go. I'm saving up
for
mine...

Bob

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