Hey gang,

Here is a letter with response from Tom Hunt, he runs modelair-tech, and
apparantly is a Senior Engineering Specialist of Structural Test for Northrop
Grumman!  I am going to reply to him and see if there could be a better motor
for the job!



Scott........

> ----------
> From:     [log in to unmask][SMTP:[log in to unmask]]
> Sent:     Thursday, September 30, 1999 1:06 AM
> To:   [log in to unmask]
> Subject:  Question...
>
> HI,
>
> My name is Scott Foster, and i am a junior at Miami University in Oxford,
> OH.
>
Miami in Oh?  when did they move Miami?  :-) last Hurricane?

>  I have
> some questions about your products and electrics in general.  I am not
> sure
> if you are aware, but every spring, Cessna and the AIAA holds a student
> design build and fly competion.  Currently at Miami we are in a design
> phase
> for next springs aircraft.
> The competition is as follows:  the student must build an electric craft,
> to
> be electric powered with a battery weight no more than 5 lbs ( i think
> about
> 40 sanyo 2000's)
> The craft we build will have ten minutes to do the following:  with
> anywhere
> from 2 to 8 one litre bottles of water, take off in 100 ft, fly one
> circuit
> with a 360 turn, then land, then we will take out the water, fly two more
> patterns then land.  This is one sortie, the team that carries the most
> water,  the most sorties, in ten minutes wins.
>
Ah.. I see they have changed the task again for this year!!  interesting!!

any particular size to the 360 turn?

> Now for my questions: 8 litres of water is about 19 lbs including bottle
> wt.
> add to that 5 lbs of batteries, and approxiamately and 10 lb airframe(
> hopefully, it could be more).   Now, in your opinion, would it be better
> to
> run two motors each on a belt drive, or belt the two motors together on
> one
> prop shaft.  Is there anyloss of efficiency, or thrust in belting two
> motors
> together as opposed to having them on separate belt drives?  We currently
> have two aveox 1412 5y's, that will share 40 2000's.  ( we also have a
> 1412
> 4y laying around)
>
Best to make a twin engine aircaft.  The only reason to gang two motors
together is when there isn't a single one available to do the job, or a
single is not terrible economical.  You get a substantial powered lift
benifit from two props overwashing a wing, than you do with a single motor
mounted in the nose... helps keep slotted flaps and slats from stalling
too!!

> Here is another question: We will need about 8 minutes of good power to
> fly
> the entire 10 minute round.  Again in your opinion, what is the BEST way
> to
> get the most power from the limited power supply( taking into
> consideration
> the plane will probably be around 34 lbs loaded)?  Any suggestions on
> motor
> type, number of them, arangement (single twin ect) and agian belt drives?
>
I don't see aproblem with getting 8-10 minutes out of a twin, but not at
full power all the time!!  You're probably going to need all that the
1412-5y's can give to get off a 35 lb model!!  about 40 cells 30-35amps
each!!  RC-2000 cells at that level won't last more than 5-6 minutes of
actually flight time.  Assuming that ripping the water out of the model is
part of your 10 minutes... that might take a minute to do safely...maybe
less..

As long as you're not planning on more than 20 cells and 16" props or
smaller per motor, than a stock H-1000 will do the job.  Ratio's available
at 2.57, 3.0, and 3.6/1

You really ought to get "ecalc"  e-flight emulation program (see aveox web
page) for $30.00 it's a wise investment.....

> I greatly appreciate Everything you can tell me, thanks a toN!!
>
> Sincerely,
>
> Scott Foster
>
>
    You're welcome anytime...

    BTW I give edu discounts to 40% on my stuff...

Respond here but CC to: [log in to unmask]
Tom Hunt
Senior Engineering Specialist
Structural Test
Northrop Grumman
516-346-9468
516-575-6619FAX)

A little bit of nonsense now and again is relished by the best of
men........ unknown