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Aileron travel

F

fly.more.work.less

Member
I'm on the home stretch towards obtaining a CofA for an RV-3A I've just imported into Australia, but have hit a small issue. In the -3B preview plans, the desired aileron travel is 30deg up and 20deg down. However, my -3A (type I wings, circa early '80s) is measuring closer to 40deg up and 30deg down.

I have emailed Van's, and am awaiting a response (will follow with a phone call next week). But, what I'd like to know is, is this a safety issue, or will it just lead to greater roll rates and higher sensitivity?

For the registration process, I must demonstrate that control limits are as per manuals/documentation etc. Which puts me in a bit of a bind: is there a chance that earlier manuals for the -3 called out different limits?

Cheers

Alexis.
 
It might very well be that the builder never installed any aileron stops - i have seen this before on early RV's. On the other hand, at least some of the control surfaces state a minimum deflection, bt not a maximum. If the manula states a maximum, and you are beyond it, then you probably need the stops.

Paul
 
Travel limits

Hi Alexis,
I agree that you should check for missing or incorrectly installed
control stops.

Excess aileron travel will not make your ailerons more sensitive,
and may not increase roll rates. My experience is that full aileron
deflection in some RV's results in flow separation that you can feel
as a vibration in the stick. Once that happens, you are unlikely to
get a higher roll rate by deflecting the ailerons further.

If your aileron travel is not limited by control stops, you could
get damage to the rod-end bearings in the system if they
are contacting the bellcrank, control stick, or other structures.
In the worst case, your aileron bellcranks could get into an
"over-center" position and lock the ailerons at full deflection.

I would consider improper control stops a safety-of-flight issue
and correct it. Installation of control stops on the inboard aileron
hinge brackets is a very easy fix that can be done without even
removing the ailerons. The stops limit only the upward travel of
each aileron; the down travel is limited by the stop on the opposite
side. If your bellcranks and push-tubes are rigged correctly,
the down travel will be within limits when the opposite up travel
stop is hit.

- Dan Benua
EAA Tech Counselor
Repeat Offender
 
aileron stops

Van's will say: 'follow the plans'. I've got 650 hrs in RV3, and the only time I hit the aileron stops is when checking control travel before takeoff, and *maybe* when doing split-S maneuver at < 100mph. Anyone who puts in full aileron in an RV3 over 100mph is asking for trouble (IMHO)! The other thing to be aware of is that stick travel in that 24" wide cockpit is an issue. Even with proper stops, the stick will hit your thighs before it hits the stops (except if stick is full fwd ... and if you're bury the stick in a corner at over 100mph, good luck...)
 
danbenua said:
Hi Alexis,
I agree that you should check for missing or incorrectly installed
control stops.

Excess aileron travel will not make your ailerons more sensitive,
and may not increase roll rates. My experience is that full aileron
deflection in some RV's results in flow separation that you can feel
as a vibration in the stick. Once that happens, you are unlikely to
get a higher roll rate by deflecting the ailerons further.

If your aileron travel is not limited by control stops, you could
get damage to the rod-end bearings in the system if they
are contacting the bellcrank, control stick, or other structures.
In the worst case, your aileron bellcranks could get into an
"over-center" position and lock the ailerons at full deflection.

I would consider improper control stops a safety-of-flight issue
and correct it. Installation of control stops on the inboard aileron
hinge brackets is a very easy fix that can be done without even
removing the ailerons. The stops limit only the upward travel of
each aileron; the down travel is limited by the stop on the opposite
side. If your bellcranks and push-tubes are rigged correctly,
the down travel will be within limits when the opposite up travel
stop is hit.

- Dan Benua
EAA Tech Counselor
Repeat Offender
Click to expand...
Ditto Dan's comments completely. In fact I consider lack of aileron stops a safety of flight issue. When I used to do Tech Counselor inspections I would always look for that and squawk it.

Aileron stops can be retroactively added by putting an AN4 bolt through the inboard bracket so that the steel aileron bracket hits it and the desired point and stops the travel.
 
Thanks all for your comments. I have subsequently installed stops to limit the up aileron travel to 30deg: only took about two hours in the end :) Received the airworthiness certificate on Monday, getting myself prepared for the RV Grin.
 
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