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Old Feb 24, 2003, 05:12 PM
jeff & vickie
Guest
n/a Posts
ok how about 8 fuel engines instead of electric

im thinking of electric but would really like to go with 8 os 40 for my
spruce scale size would give me a 14 foot wing span how would i go about
hooking up 8 engines
thank for your time and help


Old Feb 24, 2003, 05:12 PM
Don Hatten
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

Eight .40's on a 14 foot span would be overkill unless it weighs a ton. You
could probably get away with .15s or .20s. Break in all the engines on the
ground before flying with them to make sure they are ultra-reliable
especially in transition from idle to full power.

Just because of all the engines I would vote for electrifying it
(cha-ching!). It'll be a mini-nightmare trying to keep 8 IC engines running
consistently, IMHO.

YMMV
Don

"jeff & vickie" <ucwx@frontiernet.net> wrote in message
news:v5l6gmmqllmm75@corp.supernews.com...
> im thinking of electric but would really like to go with 8 os 40 for my
> spruce scale size would give me a 14 foot wing span how would i go about
> hooking up 8 engines
> thank for your time and help
>
>



Old Feb 24, 2003, 09:02 PM
Normen Strobel
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

I've seen pilots of 4 engine models take half an hour just getting the
engines running in tune before their first take off. Probably have to
double that for 8 engines. Plus Electric motors are much easier to do
counter rotating props.

But if you do decide on fuel, go with 4 strokes, it would sound awesome.

"Don Hatten" <hattend@starband.net> wrote in message
news:jdx6a.1357$eT6.420166799@twister2.starband.ne t...
> Eight .40's on a 14 foot span would be overkill unless it weighs a ton.

You
> could probably get away with .15s or .20s. Break in all the engines on

the
> ground before flying with them to make sure they are ultra-reliable
> especially in transition from idle to full power.
>
> Just because of all the engines I would vote for electrifying it
> (cha-ching!). It'll be a mini-nightmare trying to keep 8 IC engines

running
> consistently, IMHO.
>
> YMMV
> Don
>
> "jeff & vickie" <ucwx@frontiernet.net> wrote in message
> news:v5l6gmmqllmm75@corp.supernews.com...
> > im thinking of electric but would really like to go with 8 os 40 for my
> > spruce scale size would give me a 14 foot wing span how would i go about
> > hooking up 8 engines
> > thank for your time and help
> >
> >

>
>





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Old Feb 25, 2003, 08:04 AM
Mathew Kirsch
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

"jeff & vickie" <ucwx@frontiernet.net> wrote in message news:<v5l6gmmqllmm75@corp.supernews.com>...
> im thinking of electric but would really like to go with 8 os 40 for my
> spruce scale size would give me a 14 foot wing span how would i go about
> hooking up 8 engines


Operating eight (!!!) glow engines will be like herding cats. Your
original electric idea would be much simpler and more reliable. By the
time you get all eight engines running and synchronized, you'll be too
tired to fly, and the first engine will have run out of fuel

With eight glow engines, all you have to do to "hook them up" is copy
the setup on the nose of your trainer EIGHT times. Each engine needs
its own fuel tank and throttle servo. Trying to feed that many engines
from a single tank is a recipe for disaster. The distance the fuel
would have to travel is much too far; the engine can't suck fuel more
than a few inches, so you'd need pumps. I can't even fathom the Rube
Goldberg contraption necessary to run four engines from a single
throttle servo, let alone eight.

Good luck, whatever you decide.
Old Feb 25, 2003, 04:12 PM
Matthew Klarich
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

I have seen an airplane with 6 glow motors fly, it was in the back of model
aviation a couple years ago. The gentlemen who owned was flying it in
chicago and one of the district heads had helped him build it and put a
picture of it in the magazine. The motors were setup as pushers with
modified mufflers. It was a challenge to get it going, I helped start them
all one day and we had 3 glow drivers and two electric starters going on it.
I will say it was damned impressive to watch fly.

Matt Klarich
"Mathew Kirsch" <mkirsch1@rochester.rr.com> wrote in message
news:d6bf3430.0302250554.145095c@posting.google.co m...
> "jeff & vickie" <ucwx@frontiernet.net> wrote in message

news:<v5l6gmmqllmm75@corp.supernews.com>...
> > im thinking of electric but would really like to go with 8 os 40 for my
> > spruce scale size would give me a 14 foot wing span how would i go about
> > hooking up 8 engines

>
> Operating eight (!!!) glow engines will be like herding cats. Your
> original electric idea would be much simpler and more reliable. By the
> time you get all eight engines running and synchronized, you'll be too
> tired to fly, and the first engine will have run out of fuel
>
> With eight glow engines, all you have to do to "hook them up" is copy
> the setup on the nose of your trainer EIGHT times. Each engine needs
> its own fuel tank and throttle servo. Trying to feed that many engines
> from a single tank is a recipe for disaster. The distance the fuel
> would have to travel is much too far; the engine can't suck fuel more
> than a few inches, so you'd need pumps. I can't even fathom the Rube
> Goldberg contraption necessary to run four engines from a single
> throttle servo, let alone eight.
>
> Good luck, whatever you decide.





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Old Feb 25, 2003, 05:42 PM
Paul McIntosh
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

With reliable, well broken in engines, it shouldn't be all that much problem
to get 8 going. With two people starting, work from the outside in.
"Matthew Klarich" <mklarich@stoneflyers.nospam.com> wrote in message
news:3e5be34f$1_2@corp-goliath.newsgroups.com...
> I have seen an airplane with 6 glow motors fly, it was in the back of

model
> aviation a couple years ago. The gentlemen who owned was flying it in
> chicago and one of the district heads had helped him build it and put a
> picture of it in the magazine. The motors were setup as pushers with
> modified mufflers. It was a challenge to get it going, I helped start them
> all one day and we had 3 glow drivers and two electric starters going on

it.
> I will say it was damned impressive to watch fly.
>
> Matt Klarich
> "Mathew Kirsch" <mkirsch1@rochester.rr.com> wrote in message
> news:d6bf3430.0302250554.145095c@posting.google.co m...
> > "jeff & vickie" <ucwx@frontiernet.net> wrote in message

> news:<v5l6gmmqllmm75@corp.supernews.com>...
> > > im thinking of electric but would really like to go with 8 os 40 for

my
> > > spruce scale size would give me a 14 foot wing span how would i go

about
> > > hooking up 8 engines

> >
> > Operating eight (!!!) glow engines will be like herding cats. Your
> > original electric idea would be much simpler and more reliable. By the
> > time you get all eight engines running and synchronized, you'll be too
> > tired to fly, and the first engine will have run out of fuel
> >
> > With eight glow engines, all you have to do to "hook them up" is copy
> > the setup on the nose of your trainer EIGHT times. Each engine needs
> > its own fuel tank and throttle servo. Trying to feed that many engines
> > from a single tank is a recipe for disaster. The distance the fuel
> > would have to travel is much too far; the engine can't suck fuel more
> > than a few inches, so you'd need pumps. I can't even fathom the Rube
> > Goldberg contraption necessary to run four engines from a single
> > throttle servo, let alone eight.
> >
> > Good luck, whatever you decide.

>
>
>
>
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Old Mar 03, 2003, 02:02 AM
rkremser
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

I once saw a plane with a single central engine which had chain drives from
a rc car out to 4 props on the wings, maybe this is an alternative that
would work for you.

"jeff & vickie" <ucwx@frontiernet.net> wrote in message
news:v5l6gmmqllmm75@corp.supernews.com...
> im thinking of electric but would really like to go with 8 os 40 for my
> spruce scale size would give me a 14 foot wing span how would i go about
> hooking up 8 engines
> thank for your time and help
>
>



Old Mar 03, 2003, 01:12 PM
Paul Nesbitt
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

That sounds like a fun project. I think you will be fine using eight good
engines, like Paul McIntosh suggested, I would make sure they are broke-in
before you try them on the plane.

A couple suggestions:
To keep the weight down, I would not use 8 throttle servos. Depending on
the configuration of the plane/wing, I would use one or two and bell cranks
or flexible pushrods.
Also, I would suggest that you run just one (or maybe two) main fuel tanks
and put a header tank near each engine to help with fuel draw.
Finally, when you do get ready to fly the plane, don't try and peak-out
every engine or get them running the same rpm. That is not necessary. Just
make sure the engines are running well and are reliable.

Good Luck,
Paul

jeff & vickie wrote:

> im thinking of electric but would really like to go with 8 os 40 for my
> spruce scale size would give me a 14 foot wing span how would i go about
> hooking up 8 engines
> thank for your time and help


Old Mar 04, 2003, 07:33 PM
Bill Bunn
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

Didn't the Spruce Goose have 6 engines?


Old Mar 04, 2003, 07:34 PM
Don Hatten
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

Nope, 8

"Bill Bunn" <bbunn@highstream.net> wrote in message
news:3E654F12.F2F1536F@highstream.net...
> Didn't the Spruce Goose have 6 engines?
>
>



Old Mar 13, 2003, 02:12 AM
Registered User
Wasilla, Alaska
Joined Feb 2003
6 Posts
This may sound stupid but is it possible to have just two good sized engines inboard, one on port/starboard wing and have a 1 to 1 belt drive to the other prop shafts? use a pair of weedies or chainsaw motors, they have rear shafts, make single and double groove pulleys, use a good high speed set of cog belts. Then its just two engines to worry about.
Daniel Ramsey is offline Find More Posts by Daniel Ramsey
Old Mar 13, 2003, 03:02 PM
Mathew Kirsch
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

Daniel Ramsey <Daniel.Ramsey.k80am@rcgroups.com> wrote in message news:<Daniel.Ramsey.k80am@rcgroups.com>...
> This may sound stupid but is it possible to have just two good sized
> engines inboard, one on port/starboard wing and have a 1 to 1 belt drive
> to the other prop shafts? use a pair of weedies or chainsaw motors, they
> have rear shafts, make single and double groove pulleys, use a good high
> speed set of cog belts. Then its just two engines to worry about.


You'd think that, but multiple engines are easier to deal with, and
more reliable. There have been several attempts over the years to
build reliable belt-reduction systems for glow engines, because most
of the planes we fly could fly better on half the power, if only we
could drive a larger propeller at a lower RPM. At the high RPMs we run
our engines at, the props whip the air up so badly that they're
horribly inefficient. On top of that, the "pitch speed," that is, the
theoretical maximum full-throttle speed the propeller will move the
plane at, is normally far higher than the practical maximum speeds of
typical sport airplanes. For example, a 6-inch-pitch propeller running
at 15,000 RPM has a pitch speed of 85MPH, and well within the realm of
your typical .40-.46 glow engine and a 10x6 prop. Do you really think
a trainer is going to do 85MPH? Ack, I digress!

Anyway, the vibrations and such from a glow engine wreak havoc on
reduction drives, so they're a high-maintenance item. In a
belt-to-multiple-props installation, you'd have all kinds of extra
complexity and maintenance. Instead of building 8 firewalls, you'd
have to build 8 firewalls, 8 bearing carriers, strong internal wing
structures to bear the tension and torsional loads from the belts,
access to the belts for maintenance. On top of that, you need to find
belts of the proper length, pulleys, shafts, bearing blocks... On top
of that, you have to get everything into perfect alignment.
Old Mar 14, 2003, 08:02 AM
Rasman
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

I think it actualy sounds like an interesting and original project....

if you have a reduction drive on the motor which then goes to the other
props it might cut down on the maintanance mathew mentioned

"Mathew Kirsch" <mkirsch1@rochester.rr.com> wrote in message
news:d6bf3430.0303131255.7a90120b@posting.google.c om...
> Daniel Ramsey <Daniel.Ramsey.k80am@rcgroups.com> wrote in message

news:<Daniel.Ramsey.k80am@rcgroups.com>...
> > This may sound stupid but is it possible to have just two good sized
> > engines inboard, one on port/starboard wing and have a 1 to 1 belt drive
> > to the other prop shafts? use a pair of weedies or chainsaw motors, they
> > have rear shafts, make single and double groove pulleys, use a good high
> > speed set of cog belts. Then its just two engines to worry about.

>
> You'd think that, but multiple engines are easier to deal with, and
> more reliable. There have been several attempts over the years to
> build reliable belt-reduction systems for glow engines, because most
> of the planes we fly could fly better on half the power, if only we
> could drive a larger propeller at a lower RPM. At the high RPMs we run
> our engines at, the props whip the air up so badly that they're
> horribly inefficient. On top of that, the "pitch speed," that is, the
> theoretical maximum full-throttle speed the propeller will move the
> plane at, is normally far higher than the practical maximum speeds of
> typical sport airplanes. For example, a 6-inch-pitch propeller running
> at 15,000 RPM has a pitch speed of 85MPH, and well within the realm of
> your typical .40-.46 glow engine and a 10x6 prop. Do you really think
> a trainer is going to do 85MPH? Ack, I digress!
>
> Anyway, the vibrations and such from a glow engine wreak havoc on
> reduction drives, so they're a high-maintenance item. In a
> belt-to-multiple-props installation, you'd have all kinds of extra
> complexity and maintenance. Instead of building 8 firewalls, you'd
> have to build 8 firewalls, 8 bearing carriers, strong internal wing
> structures to bear the tension and torsional loads from the belts,
> access to the belts for maintenance. On top of that, you need to find
> belts of the proper length, pulleys, shafts, bearing blocks... On top
> of that, you have to get everything into perfect alignment.



Old Mar 14, 2003, 08:52 AM
Charlie Funk
Guest
n/a Posts
Re: ok how about 8 fuel engines instead of electric

Every glow engine maker cautions about over propping and the higher
temperature that results from running at lower rpm, yet we routinely fly our
planes at something less than full throttle.

Does anyone know of any hard data that exists to show the effect of
overpropping? Suppose I ran a 14 X 3 on a .60 size instead of a 12 X 6.
What temperature effect does it have? What if I ran a 16 X 3? What would
the temperature effect be?

It would be really great to see some valid engineering test data on the
subject.

--
Charlie Funk
Just Cruisin' Plus
800 888-0922
615 833-0922
www.justcruisinplus.com
We prefer the MasterCard card
"Rasman" <hmsv@webone.com.au> wrote in message
news:3e71e004$1@iridium.webone.com.au...
> I think it actualy sounds like an interesting and original project....
>
> if you have a reduction drive on the motor which then goes to the other
> props it might cut down on the maintanance mathew mentioned
>
> "Mathew Kirsch" <mkirsch1@rochester.rr.com> wrote in message
> news:d6bf3430.0303131255.7a90120b@posting.google.c om...
> > Daniel Ramsey <Daniel.Ramsey.k80am@rcgroups.com> wrote in message

> news:<Daniel.Ramsey.k80am@rcgroups.com>...
> > > This may sound stupid but is it possible to have just two good sized
> > > engines inboard, one on port/starboard wing and have a 1 to 1 belt

drive
> > > to the other prop shafts? use a pair of weedies or chainsaw motors,

they
> > > have rear shafts, make single and double groove pulleys, use a good

high
> > > speed set of cog belts. Then its just two engines to worry about.

> >
> > You'd think that, but multiple engines are easier to deal with, and
> > more reliable. There have been several attempts over the years to
> > build reliable belt-reduction systems for glow engines, because most
> > of the planes we fly could fly better on half the power, if only we
> > could drive a larger propeller at a lower RPM. At the high RPMs we run
> > our engines at, the props whip the air up so badly that they're
> > horribly inefficient. On top of that, the "pitch speed," that is, the
> > theoretical maximum full-throttle speed the propeller will move the
> > plane at, is normally far higher than the practical maximum speeds of
> > typical sport airplanes. For example, a 6-inch-pitch propeller running
> > at 15,000 RPM has a pitch speed of 85MPH, and well within the realm of
> > your typical .40-.46 glow engine and a 10x6 prop. Do you really think
> > a trainer is going to do 85MPH? Ack, I digress!
> >
> > Anyway, the vibrations and such from a glow engine wreak havoc on
> > reduction drives, so they're a high-maintenance item. In a
> > belt-to-multiple-props installation, you'd have all kinds of extra
> > complexity and maintenance. Instead of building 8 firewalls, you'd
> > have to build 8 firewalls, 8 bearing carriers, strong internal wing
> > structures to bear the tension and torsional loads from the belts,
> > access to the belts for maintenance. On top of that, you need to find
> > belts of the proper length, pulleys, shafts, bearing blocks... On top
> > of that, you have to get everything into perfect alignment.

>
>



 


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