Van's Air Force
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Advantage of electric trim
- Thread starter Flyin4Fun
- Start date
ChiefPilot
Well Known Member
Aside from being lighter as previously mentioned, the electric trim also preserves pass through space in the spar box - the manual trim cable is thick; the 22g wires for the electric trim are tiny in comparison. Depending on how you equip your plane, space to pass wires through the spar box may be very valuable.
Right question. Take monetary difference between the two and divide it by $5.80 then figure out how far your RV can reach for that difference. As you see there is no advantage.
pilottangocharlie
Well Known Member
There could definitely be an advantage to the resale value of your airplane.
I hear it can add 5 knots to your cruise speeds and 100fpm in sea level climb speed at Vx.
I hear it can add 5 knots to your cruise speeds and 100fpm in sea level climb speed at Vx.
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Jamie
Well Known Member
Practical benefit of electric trim is HOTAS ergonomics. Downside is more parts count. If I had to do it again I would probably just put electric trim on the pilot's side. Wiring trim to one set of switches eliminates the need for relays (if your switches are rated for the draw of the motors which I believe most are).
Charles in SC
Well Known Member
I went with manual because in the planes that I have flown with electric trim (more than 10) I always wound up needing to use the manual wheel in cruise flight. I found it to be more able to fine tune the trim. On an rv you do not have a manual wheel at the same time as an electric thing.
The manual pitch trim cable is a loopy thing that just takes up more foot room. How you'd snake it past a typical FI pump in the same area I don't know since I've always had carbs. The mounting tab is one more edge to dent your lower leg. It does work well, though.
Consider splitting the difference and use electric pitch and manual roll trims. Mount the switch/annunciator on the panel close to the throttle and perhaps the flap switch. You can still keep a hand on the throttle and work trim/flaps with your thumb - just like texting! - and you save the cost and complication of relays and wiring to the stick. It's also accessible for the FO.
John Siebold
Consider splitting the difference and use electric pitch and manual roll trims. Mount the switch/annunciator on the panel close to the throttle and perhaps the flap switch. You can still keep a hand on the throttle and work trim/flaps with your thumb - just like texting! - and you save the cost and complication of relays and wiring to the stick. It's also accessible for the FO.
John Siebold
MauiLvrs
Well Known Member
Or on the stick....
N941WR
Legacy Member
On the other hand...
It seems as though every plane I have flown with electric trim has had a failure of some kind and with no manual backup, you will be stuck flying your out of trim airplane until you can land and sort it out.
While that cable does weigh a good bit, I wonder how much the wiring, breaker, relays, servos, etc. required for the electric trim weigh?
The disadvantage, as mentioned above, is that it takes up one hole through the spar. For me, this really hasn't been an issue since none of my antenna cables run through the spar.
It seems as though every plane I have flown with electric trim has had a failure of some kind and with no manual backup, you will be stuck flying your out of trim airplane until you can land and sort it out.
While that cable does weigh a good bit, I wonder how much the wiring, breaker, relays, servos, etc. required for the electric trim weigh?
The disadvantage, as mentioned above, is that it takes up one hole through the spar. For me, this really hasn't been an issue since none of my antenna cables run through the spar.
L.Adamson
Well Known Member
I always rented newer planes. Most had electric trim, and I certainly wasn't experiencing a round of failures. Most of the RV's that I've flown with have electric trim. They haven't failed either. And if they happened to have the older trim "electrics" that have failed once and a while, then it's still no big deal, to switch to the newer model. In the meantime, my RV had electric roll & pitch trim on the stick. I highly preferred it.
Charles in SC
Well Known Member
If you have not bought yet you might look into getting an RV-8 cable. That is what I did, they are just a little bit longer and so it is easier to route.
L.Adamson
Well Known Member
And the same goes for electronic "glass" panels. STICK with vacuum gauges...........'cause when the glass fails, you'll be completely lost!
I just had to say that..., since N941WR just went with a glass remodel.
Reading the above, it would seem that electric trim failure is eminent sooner or later, and that some poor soul will be pulling or pushing the stick with their last gasp of weakened muscles, just to keep the near doomed plane airborne. That is far from being realistic scenario.
In reality, electrim trim in a Vans airplane is a simple to install, and reliable piece of equipment. There have been some failures of earlier trim relay boxes.............which have been replaced with an upgraded model.
Even at that, you don't have to wrestle with the airplane.
I also installed electric aileron trim. It uses a servo & tab on the aileron, which is superior to the bias spring method (elec. or manual). Trim for both aileron & elevator is with a hat switch located on the stick. For landings, this allows me to keep my left hand on the stick, while right hand is on the throttle , while I can also flip the electric flap switch located next to the throttle. Manual trim has "slop", that's induced when the cable is reversed 180 degrees to the dial. Electric trim, with it's very short push rod has no slop. Cable "slop" has apparently caused no problems, but seems to bug a few aircraft inspectors. I prefer the "ridged" no slop electric method.
BTW--- I actually DO like "glass" panels too...
Charles in SC
Well Known Member
Sorry, I do not remember the details. My -7 kit came with a cable. I read on this site that a -8 cable was a little easier to work with, so I sent my cable back to Vans and got one for a -8. It seemed to work fine.
The VP-X electronic circuit breaker system makes wiring electric trim a snap. You get rid of relays and replace them with solid state components. You get variable speed trim without any extra wiring complexity, and this takes away the "touchiness" in cruise and makes it very easy to fine tune.
Not that an RV will trim out cleanly like a Cessna 182 anyway...
Not that an RV will trim out cleanly like a Cessna 182 anyway...
