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  #1  
Old 11-29-2017, 02:56 PM
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Champ Champ is offline
 
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Location: Kingsville, Ontario, Canada
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Default C of G Trials

I haven't had a passenger since check pilot days so I am simulating aft C of Gs using next years lawn fertilizer before I do. To get it close to a rear passenger C of G I put two bags in the rear baggage compartment and one in the passenger seat - C of G is 83.77 aft of datum (range is 78.7-86.82) with full fuel and 11lb in forward baggage compartment. The aft baggage compartment has 88.4 lb in it which is over the 75 lb total design limit and the 50 lb lower area limit. Does this really matter since the C of G is within range? I feel the ballast is more secure in the aft baggage compartment than loading more in the passenger seat and possibly interfering with the stick if the worst thing happens.

Here are pictures of loading;



https://lh3.googleusercontent.com/yg...g=w450-h600-no
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Dennis Enns
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Bellanca Champ 7ACA since 1986, restored 1990.
RV-8 IO375, Hartzell CS, dual PMags.
Dues paid thru Dec 22, 2017

Last edited by Champ : 11-29-2017 at 03:26 PM. Reason: Correct picture attach
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  #2  
Old 11-29-2017, 03:06 PM
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RV8JD RV8JD is offline
 
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Dennis,

Those pictures appear to be on your computer so they won't show up here.

The 50 pound rear floor limit, and the 25 pound rear shelf limit are (I would assume) structural limits set forth by Van's. I'd be hesitant to exceed them.

If you have a concern with potential interference with the rear stick, take it out for your testing.
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Last edited by RV8JD : 11-29-2017 at 03:11 PM.
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  #3  
Old 11-29-2017, 04:19 PM
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chepburn chepburn is offline
 
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I placed two 30 lb sand bags in the aft compartment. So ten lbs over.

The rest of the weight was added incrementally in 30 lb bags to the rear seat. I put the sand bags inside of pillow cases to contain any spillage and strapped them into the rear seat... the shape of the sand bags lent themselves to be strapped tightly to the seat back.

I also removed the rear stick for a 'just in case'

I liked the 30 lb bags because it let me creep up on aft cg.


Good luck ... its a different airplane with the CG aft.


BTW... I like those baggage tie downs !



Chris
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  #4  
Old 11-29-2017, 04:32 PM
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Toobuilder Toobuilder is offline
 
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Depending on what your definition of "trials" is, be aware that adding a bunch of weight in the aft compartment will result in a very different MMOI than really "simulating" a passenger with realistic weight in the back seat - despite the CG being identical. Not a big deal if you are just looking for trim effectiveness, but can be a very big deal for spin recovery or other dynamic maneuvering.
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  #5  
Old 11-29-2017, 04:56 PM
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I don’t plan on doing any spins or other dynamic manuevers with ballast for aft C of G just want to get the effect on landings.
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Dennis Enns
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Bellanca Champ 7ACA since 1986, restored 1990.
RV-8 IO375, Hartzell CS, dual PMags.
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  #6  
Old 11-30-2017, 08:17 AM
Robert Anglin Robert Anglin is offline
 
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Location: houston, texas
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Default Same here.

We did the testing with cases of oil and cases of drinks so we would be able to use it up and not have sand or corrosives in the plain. As best I can remember we loaded to 50 lbs. over gross, 15 Lbs. in front of forward C.G. and 15 Lbs. aft of most rearward C.G.. But all that was with each station loaded correctly and tied down. We only tested at these weights and positions in faze one and a one time test before we would let anyone ride in this aircraft. The aircraft behaved very well and was more than controllable in "standard limits" flight and stalls. As it was loaded to full weight it was sinking quite a bit but nothing a fat and heavy C 210 would not do on final. Doing this very carefully gives us confidence that the airframe will do and handle the set out limits from Van's and we got to see how it would handle at those limits in order to get a feel for them. It is a good airplane. Always respect the "aerobatics envelop" and you will like what you find. Hope this helps, Yours, R.E.A. III # 80888

Last edited by Robert Anglin : 11-30-2017 at 08:32 AM.
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  #7  
Old 11-30-2017, 08:36 AM
dtw_rv6 dtw_rv6 is offline
 
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At the risk of stating the obvious, I would not recommend loading the aircraft to aft cg on the first trial. I'd start with an incremental change from a well known loading configuration, then move the loads gradually until you've fully explored the envelope.

I realize that I haven't given any specifics around incremental and gradually -- you'll need to develop the plan based on your knowledge of the plane and possibly input from others here more experienced than me.

Good luck!

Don
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  #8  
Old 11-30-2017, 09:54 AM
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Thanks guys. I'll change my loading so as not to exceed the aft baggage compartment limit and put more weight in the rear seat, with the rear stick removed for added safety & piece of mind.

I'm going back 1" at a time with C of G.
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RV-8 IO375, Hartzell CS, dual PMags.
Dues paid thru Dec 22, 2017
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