R

rbregs

Active Member
I'm leaning towards manual trim for both elevator and ailerons. I am interested in what trim actuation method you chose, and why.

Also, what are you thoughts about your selected method of trim actuation after having flown your RV-8.

As always, thanks in advance for any information you may provide.

Bob
 
MeToo

Bob,
Glad to see your question cause it's one of the items I'd like to get some feedback about too. I have been planning to install an electric elevator trim system and a manual ail trim. Most of my flying has been with electric systems so I was really leaning in that direction. I had the opportunity to fly a -8 with electric trim and thought it was perhaps a little too sensitive ( I think I would get used to that though).
Also, I believe there are electronic servo controllers that would allow one to adjust the speed/sensitivity of the trim actuator to suit individual preferences.
I flew a friends -6 the other day that had manual trim. I really loved it. It offered me a very good feel and seemed to be extremely precise in it's adjustments without any of the hunting for the sweet spot I experienced with the electric trim. I had never seen a Venier controlled trim before and I was really surprised how natural it felt.
I'm still leaning toward electric trim because I don't have to take my hand off of the stick to use it.
However, I think the manual system weighs less and has less to go wrong. Also, I'm not sure if there are issues with runaway trim ( If there are - ample stick force/elevator travel may be available to overcome any problems).
At this point I have not made a decision yet but the weight issue and the precision adjustment feel of the manual elevator trim is very attractive.
As for ail trim I have decided to go with the manual system because of frequency of use, wt. and no extra electronics.
I'm anxious to see what others have to say.
Steve
 
Think about your type of flying

rbregs said:
I'm leaning towards manual trim for both elevator and ailerons. I am interested in what trim actuation method you chose, and why.

Also, what are you thoughts about your selected method of trim actuation after having flown your RV-8.

As always, thanks in advance for any information you may provide.

Bob
Click to expand...

Bob,

I am still building but I can give you my thoughts. I am going full electric, elevator and aileron. I contemplated manual aileron trim but I plan to run the elevator trim to a HAT switch on the stick so it was logical just to go with electric for the aileron to the other side of the switch. This is the way it is on most fighter aircraft and something I am used to sort of, it has been few years since I have flown a fighter. I plan to get into formation flying and when doing that you do not want to look away to trim the airplane. This will come into play if you are doing a formation approach and slowing to approach speed. You can get by with manual trim, but you would have to move out to a wider formation position to trim the plane then move back into position. Electric trim is convenient more than anything. There are ways to slow the trim down so that it is not so sensitive at higher speeds.

Cheers
 
No flight experience with it, but I'm building electric trim all around. I plan on running the trim circuit with a SPTT switch to allow a Trim off, High speed trim, and Low speed trim so that the trim can be responsive in the pattern, yet not too quick in cruise. The run away can be prevented by removing power to the servos. My question is with power removed, will the servos maintain the previous position or will they be free to move?
 
Fully manual

rbregs said:
I'm leaning towards manual trim for both elevator and ailerons. I am interested in what trim actuation method you chose, and why.

Also, what are you thoughts about your selected method of trim actuation after having flown your RV-8.

As always, thanks in advance for any information you may provide.

Bob
Click to expand...

I have manual elevator trim, and I'm happy with it. I only need a couple of turns (or less) on the knob to trim the plane for any phase of flight. The only drawback is that (at least on my installation) the manual trim cable interferes with the linkage between the front and rear seat throttles. I planned to install a rear seat throttle, but I ended up not doing so because of this.

I installed manual aileron trim, but I never connected the springs. I left them off for the Phase I testing and just haven't bothered to remove the floor to install the springs yet. It might be nice for long flights, but for shorter ones I haven't missed it.
 
Electric

I'm going electric-I've flown both manual and electric trim RVs and prefer the electric 'coolie hat' on the stick.

I plan to use the Safety-Trim controller system offered by SteinAir (see the Trim Control link on their site); this should address most, if not all, of the issues associated with electric trim.

Regards,
Mike
 
Manual--Manual

I've only got 90 hours on my -8 but so far I love both the manual aileron trim and the manual elevator trim.

The aileron trim state changes due to fuel burn...switching tanks every 15 minutes bites, so the trim comes in handy.

The elevator trim really is slick. I thought the electric trim would be the first modifaction I undertook, but I like the spin to win trim cable.

Go whichever way pleases you the most...this is one of those "there is no wrong answer" questions.

Tim
 
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My 2 cents

RVG8tor said:
Bob,

I plan to get into formation flying and when doing that you do not want to look away to trim the airplane. This will come into play if you are doing a formation approach and slowing to approach speed. You can get by with manual trim, but you would have to move out to a wider formation position to trim the plane then move back into position.
Click to expand...

I agree with Nemo. I plan to use my -8 (I'm still building) for formation duty as much as possible so that's why I went electric. I don't think you can go wrong either way.
 
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I plan to get into formation flying and when doing that you do not want to look away to trim the airplane. This will come into play if you are doing a formation approach and slowing to approach speed. You can get by with manual trim, but you would have to move out to a wider formation position to trim the plane then move back into position.
Click to expand...
:eek: Who's teaching you formation :confused: OK - I might be from a military background, but you should be taught, after the early stages, to operate all controls / do all checks (including manual radio freq changes) whilst in "position" in thick IMC... I cannot comprehend anyone teaching you to move out to "trim" ?

To the original poster, we have found no need for aileron trim... It's a tandem and we have not seen any noticeable trim need due to fuel asymmetry (albeit acknowledging someone above feels they do ;) ). The Van's manual Aileron Trim adds a heavy spring / feel system to the ailerons that we were not happy with, so just never put it back in with the final assembly...
 
My thoughts and questions all in one:

I have manual trim on my bought -4 and love it. I rarely have to make trim changes due to the way I fly (fast all the time until just before final) but when I do make trim changes they are big. I LOVE the manual trim because I can nail it in less than half a second just by trimming off the stick pressure. With electric I doubt you could trim this fast, as accurately. Obviously you learn to fly what you have and no one with electric trim has any problems, I'm just saying I like the FEEL of manual trim.

Okay, so that said, what to do with the -8 I'm building. The tail I bought came from previous owner with electric so 1 point for electric. For me I think it'll come down to this, with the full auto pilot I'm going to have do I need aileron trim at all. If I decide I need aileron trim I'll probably go electric so I can have both on a hat switch. If I don't do aileron trim at all as switching tanks and riding the autopilot is enough I'l go manual on the elevator.

Anyone have a real weight difference, it can't be much for either system really??
 
I'll second that...

Andy Hill said:
To the original poster, we have found no need for aileron trim... It's a tandem and we have not seen any noticeable trim need due to fuel asymmetry (albeit acknowledging someone above feels they do ;) ). The Van's manual Aileron Trim adds a heavy spring / feel system to the ailerons that we were not happy with, so just never put it back in with the final assembly...
Click to expand...

My experience exactly. My '8' has electric aileron trim and I find it rather worthless. I doubt that I have used it in the last 50 hours. Electric elevator trim works great, you just need to fine tune the rate at which it moves.

John Clark
RV8 N18U "Sunshine"
KSBA
 
I originally ordered Electric pitch trim and manual aileron trim. When I saw the aileron trim mechanism, I thought is was kind of cheesy...and at the same tie, I decided to get a stick grip with a coolie hat trim switch. Wanting to use that grip, and wanting to keep things fairly standard, I decided I wanted to hat to work as designed - fore and aft for pitch, left and right for roll, so went with the electric aileron trim as well. I use it quite a bit actually - although it won't handle a complete fuel imbalance, it will cover an hours worth of difference.

Worth it? That depends on how you're going to fly the airplane, what you're used to, etc....This is just my own experience.
 
I put the Vans manual aileron trim in my RV8 and was unhappy with the fuction. So i changed to a vernier control which i think will work better. I can't speak to how well it will work and never will as i have to put my project up for sale soon. I will be listing it on the classifieds here shortly. But i do have some pics if you want to see one. tony
 
Thanks for replies

Thanks everyone for your replies. I really appreciate all the responses, along with this forum and the ability to poll others on their experiences and perspectives.

I'm going to stay with manual activation for both the ailerons and elevator. It simplifies flight controls and systems, from a wiring perspective, and appears to be both effective and adequately sensitive from a controls perspective.

Thanks,

Bob
 
I had a new 182 with both manual and electric trim. I always ended up grabbing the wheel and trimming by hand because I didn't like the speed of the electric trim. I liked the feel of it. I haven't heard many stories about runaway trim and suspect that there's a fair bit of 'I've heard it can happen' kind of talk.

I can say that I was surprised at how big and heavy the bowden cable is for the manual trim - it's not like you're picking that to save weight or installation complexity. It's more a question of feel.
 
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