LAMPSguy

LAMPSguy

Well Known Member
NOT yet a builder, just a lurker and thinker.

Are there ever any problems with CG in these aircraft?
If so, has anyone thought of/does anyone think this could work: The Concorde had free space in its fuel tanks, had them in multiple locations and had a transfer pump to shift the CG to aid in trim.

Could you put a tank in the fwd baggage area and one WAY back in the tail and pump water around to aid CG? It surely would add weight and complexity, just thinking that you could essentially keep CG the same throughout more of the flight using this method. Could even do calcs and make it semi-auto...just a random solution to a problem that may not exist, just mentally tinkering, go easy on me please.
 
Too mush overkill!

Unless built to extremes, these aircraft do not have CG problems. If you build with a light engine/prop combination, you may be limited to minimum baggage or add ballast in the form of a heavy prop crush plate.
Nothing in these aircraft would justify what you are talking about.
 
Not Needed

Van would have included it in the design, if he thought it was needed.
Concentrate on shop and tool requirments, and a way to finance your tail kit!
 
-8A CG Considerations

1122 lb. with a forward Oddesy (sp) battery. 10 lb. toolkit in fwd baggage compartment (to avoid potential magnetometer interference), 25 lb. of lead shot in the aft baggage compartment to keep the CG comfortably aft of the forward limit. Lots of nose up trim on final.

Handles very well.
 
It's a "non problem"

It would seem that the big engine, C/S prop airplanes are a bit heavy in the nose when flying solo, but after flying such an animal, it's not a "problem"... I need full nose up trim and some back stick to keep the speed down to where I want it in the pattern, but that's it.

There was some discussion some time back about adding a balast container in the form of a 3" dia tube spanning the fuse sides under the stab. The thought being that you would simply place a slug of lead back there when solo. I think that still has some merit and if building from scratch I would do it, but it's not even worth the trouble to retrofit an existing airplane.
 
[No experience of, nor intended, to RV-8A]

Are there ever any problems with CG in these aircraft?
Click to expand...
'Problem' is a strong word, 'issues' I might agree with ;)

Properly thought through at the build stage i.e. engine / prop / battery, the aircraft has no significant CG issues in 'normal use'. However:
  1. It is somewhat difficult to 3 point solo, easy to 'wheel'.
  2. Dual, v-v i.e. easy 3 point, difficult (bouncy!) to wheel on
  3. It is a lovely aircraft to aerobat dual, near the aeros aft CG limit.
  4. Conversely, solo, aeros are less pleasant - heavy stick forces - especially a number of successive aeros flown to a tight pattern e.g. a display / competition / in formation.
If I was to build from scratch again (not intending to), and plan to fly the same profiles I currently do (displays, including formation aerobatics), I would look at a partial solution as you describe - indeed, I have considered it. However, only to the extent of fitting, in the rearmost bay possible, a water tank. No pipes / pumps / forward tanks (which would not be far forward enough to affect CG much) - just 1 tank easily filled / emptied / checked. It would require some discipline to ensure you did not inadvertently leave it full when 2 up / baggage in rear area.

I currently display with 55lbs of ballast in the rear baggage area - well secured - and it makes a real difference ;)

Andy
RV-8 G-HILZ
RV8tors
 
I was wondering about this also. What about the 180hp RV4 with constant speed Hartzel prop? I have been told it has forward cg when flown solo & usually ok with passenger? I would assume this is something you learn to deal with or put some ballast in back. Have also been told RV8 is much better on these issues.

Would like some thoughts.
 
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