I know the DTA manual for the Voyager. It doesn't say anything like that. That was a just a joke. But I would suggest you throw it out anyway, only after letting me know the time and place two days in advance :).
Abid
--- In Sport_Aircraft@yahoogroups.com, "Jim Bair" <JimBair@...> wrote:
>
> Abid,
> I believe that was pretty close to the wording in my Aerotrike, which was a
> fine trike. I have no idea why you would make a comment like "Throw that
> trike out the window" over wordage such as "CG should be in the vicinity of
> the rear seat." Frankly, that seems like quite a common sense approach to
> me. The rear seat is pretty much the recommended CG position, is it not?
> So what's the problem?
>
> And maybe it was my DTA manual as far as that goes. I'm not really sure.
> And so what if it was? That's a fine trike, too, and if the CG is pretty
> much in the location of my back seat, I know I won't land on my nose wheel.
> So what's the big deal? I'm not even sure I have a translated POH for the
> DTA. What does it say the CG range should be? In English, please, not
> Urdu. :) (Or French. I already have that version.)
>
> Jim
>
> ----- Original Message -----
> From: apollonorthamerica
> To: Sport_Aircraft@yahoogroups.com
> Sent: Sunday, October 04, 2009 11:23 PM
> Subject: Re: Light-Sport Aircraft Yahoo group WSC Weight and Balance
>
>
> Hi Jim,
> I have never read this in any trike POH:
> "CG should be in the vicinity of the rear seat."
>
> Throw that trike out the window :).
> And if its your DTA POH that says that. May be its a bad translation from
> French but throw it out anyway, and let me know when and where, I'll clean
> it all up for you :).
> Abid
>
> --- In Sport_Aircraft@yahoogroups.com, "Jim Bair" <JimBair@> wrote:
> >
> > Hi Gary,
> > Trikes often have some fairly vague things in the POH like, "CG should
> be in
> > the vicinity of the rear seat." And if it is, quite honestly that is
> fine.
> > As you know, in fixed wing as well there is some leeway even though the
> W&B
> > chart is very black and white. If you find yourself in the upper right
> > corner of the chart (like the typical FAA test example. haha) and then
> you
> > add just 2 more pounds and you're outside the line, it doesn't mean the
> > plane will automatically crash. The really critical thing in trike CG is
> > that it result in the mains being lower than the nose wheel so you don't
> > land on the nose.
> >
> > As far as the wing position, sometimes I find it more clear to think in
> > extremes. If you hang the trike from the nose of the wing, it would fly
> > very fast and very straight down. If you hang it from the trailing edge,
> > the wing would go nose up and stall. But somewhere in the middle is the
> > magic spot where everything is in balance and it flies perfectly. That
> > occurs at probably in the vicinity of 20-35% MAC just like an airplane.
> > (Somewhere forward of center of the wing.) Don't get hung up on the
> precise
> > numbers, just the concept. (I'm not trying to set up some quibble
> thing.)
> > The manufacturer sets the wing up so you have a range in which to hang
> the
> > trike from it. And that range usually isn't very large. Like 1 1/2" or
> so.
> > Can you go outside that? Usually, but you're now experimenting. My
> > Aerotrike flew much better when I drilled a new hole about an inch
> forward
> > of the former most forward hole. You just can't get too carried away.
> >
> > All of this stuff is why you do W&B on an experimental before you even
> fly
> > it. If you design and build an airplane in your garage (perfectly legal)
> > the FAA will come inspect it for you and look at your W&B calcs as part
> of
> > your required paperwork. If the CG is way outside the normal range of
> where
> > it normally lies in relation to the MAC of the wing, they will do you
> the
> > favor of letting you know your craft will most likely crash. This is
> > something you'd like to know before flying the thing. Keep in mind, this
> > whole thread started because an individual brought up the fact he had
> hit on
> > the nose wheel a couple of times and that causes real control problems.
> > This is why CG is important.
> >
> > Jim
> >
> > ----- Original Message -----
> > From: Gary Orpe
> > To: Sport_Aircraft@yahoogroups.com
> > Sent: Sunday, October 04, 2009 9:55 AM
> > Subject: RE: Light-Sport Aircraft Yahoo group WSC Weight and Balance
> >
> >
> >
> > Does it make any difference what position the wing is in? I know that
> you
> > have to have a known position on fixed wing and then measure. Also CG
> > doesn't mean anything unless you have the manufacturers data on what the
> CG
> > should be and the way to measure it.
> >
> > Are trikes different than this?
> >
> > Gary O.
> > N181RL
> > 661 746-4780
> >
> >
> > -----Original Message-----
> > From: Sport_Aircraft@yahoogroups.com
> > [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of Jim Bair
> > Sent: Sunday, October 04, 2009 6:58 AM
> > To: Sport_Aircraft@yahoogroups.com
> > Subject: Re: Light-Sport Aircraft Yahoo group WSC Weight and Balance
> >
> >
> >
> >
> >
> > > >More likely W&L Weight and Loading.
> >
> > > Not really. The Weight and loading is easy.
> > > We add your weight, my weight, the fuel, and the trike,
> > > and see if it adds up to less than 992. It does.
> > > I can do that in my head.
> > > No, our concern is what you mentioned about the
> > > nose wheel hanging lower.
> >
> > You must have done this plenty of times Jim,
> > ... it must be quick and easy for you.
> >
> > How about doing just one more for the considered
> > loading (Richard doing his checkride with you),
> > and put it in the group files?
> > front seat 300
> > rear seat ~178
> > fuel 30
> >
> > I've never seen a sample of a WSC weight and balance
> > in any text book.
> > (showing as you promise "nosewheel height")
> >
> > Thanks,
> > Mike
> >
> > WSC W&B is like any other W&B, so there doesn't have to be a sample of
> > WSC
> > specific W&B in the textbook. In almost every textbook I have seen there
> > is
> > the generic teeter totter examples so that the pilot understands the
> > concept
> > of weight x arm = moment and that when all the weights are added up and
> > all
> > the moments are added up, you simply divide the total moments by the
> > total
> > weight and you have the CG. In trikes, the CG is typically "in the
> > vicinity of" the rear seat, and simply has to be behind the hang point
> > for
> > the rear wheels to hang lower than the nose wheel. Once the CG of the
> > trike is determined (this involves weighing the trike with scales at
> > each
> > wheel) it is simple to measure out the locations of the front seat, rear
> > seat, fuel tank, baggage area, etc., and plug in the numbers. I made a
> > spreadsheet for my W&B worksheet (or W&L worksheet, I don't care what
> > you
> > call it. Same math.) for each trike so I could plug in the numbers for
> > each
> > one with some various loading scenarios. I don't have the DTA one here
> > at
> > the house, but I do have a copy of my old aerotrike paperwork and for a
> > 300#
> > guy, which I happened to choose for the worst case scenario, the math
> > showed
> > that the CG was still aft of the hang point location, meaning the trike
> > would hang lower in the rear than the front.
> >
> > I did look in the SP written test study guide and you are correct, the
> > chapter on W & B is really lame. Even for fixed wing people there is
> > almost
> > nothing on W & B. Probably because at the LS level, our loading options
> > are
> > so limited that there is more concern with weight than with the balance
> > part. However, when we have a triker say he'd had a problem with landing
> > on
> > the nose wheel a couple of times and it wasn't very pleasant, that
> > should
> > tell him that he should figure out what's going on. Any textbook at the
> > Private Pilot level and above will have some info on how to do basic
> > weight
> > and balance and certainly an instructor textbook should have it so when
> > you
> > say you haven't seen WSC specifically addressed, I believe you. However,
> > you will be able to figure it out for a trike because the concept is no
> > different.
> >
> > Personally, I didn't use the EAA supplied W&B paperwork. I made my own
> > because it was more complete and had examples of a variety of loading
> > scenarios to cover about any contingency. A story that was related to me
> > once underscored the importance of understanding this and knowing how to
> > calculate it. Triker is approached by a cameraman wanting ot attach a
> > movie
> > camera to nose. Triker says OK. Next day, cameraman shows up with a
> > camera
> > twice as big and attached to about a 3' boom to attach to the nose.
> > Warning
> > bells go off in triker's head. He understands W&B and does a calculation
> > and determines nose will be hanging low. That's why every triker should
> > understand the concept. So when someone comes out with something out of
> > the
> > ordinary, be it a camera on a boom or a 320# student in front, he knows
> > to
> > do the WxA=M thing and figure his CG. Only tools needed are a tape
> > measure,
> > scales, and some sort of plumb bob for extra accuracy.
> >
> > Jim
> >
>
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