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View Full Version : Aft C of G snag


TwoDeadDogs
23rd Apr 2002, 07:03
hello all
I need some tips/gen/advice on sorting out an aft C of G on a small side-by-side two-seater. It requires the stick to be held forward of neutral to sustain level flight. It's tiring to fly for too long.Any sensible suggestions appreciated.
regards
TDD

Hairyplane
23rd Apr 2002, 07:13
2 Dead Dogs

Like the name!

Is the CofG really too far aft or are you assuming that this is so because of the stick forces required? The Cof G can be adjusted with lead, shifting the battery etc.

If it is merely a trim problem then some experimentation with a simple additional aluminium trip tab - bend it until the desired effect is achieved - should do the trick.

However, if this is a Permit aircraft then I suggest you call the PFA. THere is no doubt that they will give you all the necessary advice and contacts to sort this.

VBR

Hairyplane

Genghis the Engineer
23rd Apr 2002, 21:26
2DD,

I'm guessing that it's a PFA permit 2-seater, in which case your best first port of call would be Francis.D.

However, if that isn't getting you anywhere, or it's somebody else's responsibility, the following information would help to answer you...

- What's the declared CG range, where are you in it.
- What are these in %smc
- What are the measured stick free and stick fixed apparent LSS gradients.
- What sort of mechanism on the elevator, horizontal stabiliser and pitch trimmer.
- What's the tailplane volume coefficient?
- What power setting are you using when this occurs, how does it vary with power.

Appreciating you may not want to jeapordise your anonymity, the type might help too ! Failing that at-least the general configuration (high/mid/low wing, ditto tail, mid/high powerplant, pusher/tractor, MTOW, power, CAS speed range).

Finally, what do you have scope to change - one can always bolt things onto surfaces, but can you change any of the following...

- Aileron droop / reflex
- Wing incidence
- Tailplane incidence
- Elevator gearing

G

Shaker One
29th Apr 2002, 12:57
2DD
No sensible advice on your predicament but on another note - search contacts - there's something there for you.

Cheers!

----

Shaker One :)

TwoDeadDogs
5th May 2002, 01:44
hi there
Apologies for not replying sooner. The aircraft in question is a VP-2.The exact details of the C of G range are in the post,so to speak.i'll pick your collective brains soon.
regards
TDD:p