Today's Message Index:
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1. 09:16 AM - Re: Sky Scout Plans (DonkDoug)
2. 10:20 AM - Re: Sky Scout Plans (DonkDoug)
3. 08:31 PM - Re: Re: Sky Scout Plans ((null) raykrause)
4. 09:41 PM - Re: Sky Scout Plans (DonkDoug)
Message 1
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| Subject: | Re: Sky Scout Plans |
Ray,
I was looking at your weight and balance info and I have a question. Did you estimate
the pilot moment arm location or did you determine the actual location
by weighing the airplane while sitting in it? The reason I ask is because when
I looked at the weight and balance sheet Bernard Pietenpol published for his
1966 Air Camper you can calculate that he used a location approximately 16"
forward of the point where the pilot seat back and bottom intersect. In that
the seats for the Sky Scout and Air Camper have about the same geometry if you
were to use the same distance it would put your pilot moment arm at approximately
36" from your datum, the leading edge of the wing. That, of course, would
make a significant, favorable difference in your CG location.
Doug
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=472512#472512
Message 2
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| Subject: | Re: Sky Scout Plans |
Ray,
After re-reading my last post I need to correct some imprecise wording on my part.
From the 1966 Piet W/B info I calculated the pilot moment arm location was
about 16" forward of the seat intersection point.
Doug
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=472517#472517
Message 3
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| Subject: | Re: Sky Scout Plans |
Doug,
For that number, I used a more recent publication of W/B calculations in one of
the recent Brodhead newsletters. It seems to have come from the old CAA. It shows
three graphs based on seat back angle and pilot weight that gives inches
ahead of the seatback/seat bench angle for the CG of the pilot. My seat back is
15 degrees, I'm 200 lbs, it offered 7.5" ahead of the angle for the pilot CG.
That's what I used.
Still, the best fix would be the fuselage front 2" longer, or a longer motor mount.
That would really solve the problem. Remember that when you build. I would
go with the longer mount so the motor would be further ahead of the gear but
still the same in relation to the LE. I would also shorten the front leg of
the gear so the wheel weigh point would be closer to the LE. Bernard, in his
last plans for the Covair engined AirCamper, said the gear should be .5" behind
the LE.
If you use 20-21" wheels as I am, the fuselage "slope" is really steep, but I
can't remember the angle (AOA) right now but there is a lot of prop clearance.
I will get the angle tomorrow. Smaller, lighter wheels would help my CG.
RAY
Sent from my iPad
> On Sep 5, 2017, at 9:16 AM, DonkDoug <douglas.wright@okstate.edu> wrote:
>
>
> Ray,
>
> I was looking at your weight and balance info and I have a question. Did you
estimate the pilot moment arm location or did you determine the actual location
by weighing the airplane while sitting in it? The reason I ask is because
when I looked at the weight and balance sheet Bernard Pietenpol published for
his 1966 Air Camper you can calculate that he used a location approximately 16"
forward of the point where the pilot seat back and bottom intersect. In that
the seats for the Sky Scout and Air Camper have about the same geometry if
you were to use the same distance it would put your pilot moment arm at approximately
36" from your datum, the leading edge of the wing. That, of course, would
make a significant, favorable difference in your CG location.
>
> Doug
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=472512#472512
>
>
>
>
>
>
>
>
>
Message 4
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| Subject: | Re: Sky Scout Plans |
Ray,
I think that CAA material you referenced got the pilot CG about right. When you
mentioned the Brodhead newsletters I dug out William's article on Piet W/B for
Continental powered ships. He had calculated pilot CG location for each of
the airplanes he weighed. The location is very close to what you had calculated.
The mean of the values was about 7" forward of the seat bottom/seat back
intersection. Now I need to figure out how I fouled up the calculation from
Mr. Pietenpol's 1966 W/B sheet. I think my assumption as the where there is 8
gallons of fuel stored was incorrect.
Doug
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=472542#472542
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