Re: Light-Sport Aircraft Yahoo group WSC Weight and Balance

OK, I get your joke now.  Unfortunately for you, that trike is already sold and won't be thrown out.  Yes, I am aware that it was a kit.  My son and I built it.  It was the trike he learned to fly in.

 

I think you are missing something in our conversation here.  The trike CG will vary depending upon loading.  If you are in the front seat, it will have a different CG than if I am in the front seat.  And in either case, the CG will be in the vicinity of the rear seat and the mains will hang lower than the nose and everything will be fine.

 

Jim

 

----- Original Message -----

From: apollonorthamerica

To: Sport_Aircraft@yahoogroups.com

Sent: Monday, October 05, 2009 7:51 AM

Subject: Re: Light-Sport Aircraft Yahoo group WSC Weight and Balance

 

Aerotrike Safari in the US came as a kit (not an approved kit) so its quite possible their manual said that. But in a manufactured trike, that location is selected for you and done. You don't to guess where it will be exactly. It is only in one spot figured out by the manufacturer. Do you know if your Aerotrike Safari carriage was constructed from a kit?
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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