RV7A Aft CG Restriction

[nobubbles63]

I know this subject has come up many times with regards to the A models and how to deal with the rearward CG tendency.
My query is...based in the UK, when seeking to have the day/VFR restriction removed from an aircraft, the controlling authority places an aft CG limit on the aircraft the same as the recommended aero limit of 84.5". For a normally fitted out touring aircraft it is proving very difficult to fly within this limit.
My question is...in the US, are there any similar restrictions on the rearward CG when operated in IMC? I am trying to find data/justification for the aft limit restriction.
Many Thanks
Derek Cowan

[BobTurner]

Short answer: no.
Longer answer: in the US the government is pretty much hands off experimental aircraft. The builder sets the cg limits, although most have enough sense to follow Vans’ recommendations. The current ‘standard’ operating limits for ifr operations address flight instruments and radio navigation, only.

[nobubbles63]

Thanks for the reply Bob

Derek

[scrollF4]

Originally Posted by BobTurner

Short answer: no.
Longer answer: in the US the government is pretty much hands off experimental aircraft. The builder sets the cg limits, although most have enough sense to follow Vans’ recommendations. The current ‘standard’ operating limits for ifr operations address flight instruments and radio navigation, only.

And to amplify Bob's great response: As one who flies my RV-7A in hard IFR both light and heavy weight (but always within the Van's recommended CG limits), I have had zero problem trimming up KELLI GIRL and flying the needles. I'd be curious to know why your gov agency has pressed you with this CG restriction. It's just such a non-issue.

[RV7A Flyer]

Originally Posted by nobubbles63

when seeking to have the day/VFR restriction removed from an aircraft, the controlling authority places an aft CG limit on the aircraft the same as the recommended aero limit of 84.5".

That's weird. What is the reasoning here? Do they not have such a thing as different envelopes for Aero/Utility/Normal?

[swisseagle]

Go for the 320 engine mount, this will bring your engine 2" more forward and helps some.

[nobubbles63]

Thanks for the replies guys....this is what I'm trying to figure out, where is the info/data that dictates why the CG is restricted to the rear aero limit (84.5) for IFR/IMC operations. I am awaiting a response to my query to see where we go from here. If the limit sticks at the aero limit it does prevent any comfortably trimmed and equipped 6A/7A from IFR ops two up (forgetting any baggage). Your responses have been helpful...so it is just a UK thing it seems. Van's themselves have been helpful echoing the same response.
Thanks
Derek

[RV7A Flyer]

I found this

http://www.lightaircraftassociation....0procedure.pdf

on page 6 lists RVs "with restricted aft CG limit", but no explanation as to why.

What if you just got it certified with ONLY the normal limits in the documentation? Then what? Granted you couldn't fly aero, but if you don't intend to do that, how would they specify the "restricted aft cg limit"?

[nobubbles63]

Yes you are correct, the document you have found does specify the restricted aft CG limit for IFR flight (which is the aero limit) but does not give reasoning. The aircraft is placarded with the normal category CG range for VFR day flight and if cleared for IFR/night then it is re-placarded showing the new aft limit for those flights. But you are correct there is no explanation why. The authority in the UK, the LAA set the CG ranges allowed in our case - not the builder/flyer.

[rv8ch]

Might want to jump over the the RVSQN group and ask there - I vaguely recall some discussion about this a while back, but I was not really paying it much attention. https://groups.io/g/RVSqn