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RV-12 horizontal stabilizer tips

Here it is Gary. Roger? Gary?

At Hoquiam, Wash. - KHQM.

i-dV9Vfnd-L.jpg


First Flight 3 Apr 2013
Currently at 105 flights - 79 hours.

Bob Bogash
N737G
 
I have also purchased and installed the tips.
I still have to do a little sanding in a few spots to help it fit better but they do look good !
I wasn't happy with the clip on nutplates so I drilled and riveted different ones in place which gives it more of a flush surface when you put in the screws.
I think it would be be easier if they didn't come with any holes in the tabs and then when you mark and drill through the tips it will put an aligned hole in the tabs for the nut plates to line up.
It's just my opinion of making it easier and you don't have to drill the tips to match the tab holes.
They are well worth what I paid and once the plane is finished and painted they will really make it look good.

Terry
 
Agree 100% Terry - I think you nailed it. I'm definitely gonna follow your scheme the next time.......

Bob Bogash
N737G
 
Christmas special on the RV-12 stabilizer tips until December 21st
discounted from $149.95 plus shipping to
$125.00 FREE SHIPPING to the lower 48 of the USA
contact me
by email [email protected]
or call 210 497-3801 8am-5pm central
HAPPY HOLIDAYS TO ALL
 
Fillers?

Clint - how about a 'plug' to fill those wing tip 'hand grip holes' in at lease a semi-permanent fashion. Maybe two piece with two or four long screws to hold the top to the bottom. Kinda goes along with your stab tips, I think. Best:cool: to you.
 
Clint - how about a 'plug' to fill those wing tip 'hand grip holes' in at lease a semi-permanent fashion. Maybe two piece with two or four long screws to hold the top to the bottom. Kinda goes along with your stab tips, I think. Best:cool: to you.

My company is currently working on this EXACT project, and have been for awhile now. I just need for normal business to slow down enough to allow time for completion of this project. I mentioned awhile back to Clint that I was pursuing this, so that perhaps we wouldn't both be spending R&D dollars on the same thing. I don't want to hijack his thread here, and until I pay Doug to become an advertiser I don't want to elaborate. But they ARE in the works.

Maybe it's just me, but I can't stand the sight of the hand-holes!

** And for anyone 'on the fence' about buying Clint's Stab tips, do it! They really make a nice-looking addition to your airplane. Take your time and fit them tight, and they look superb **
 
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Builders, I know there are many of you that have installed the stabilizer tips. Would a few of you be kind and email me some pictures of your finished RV's with the tips installed. I am trying to get together some pictures for advertising. any help would be much appreciated. [email protected]
 
I currently have another batch or stabilizer tips in stock and ready to ship.
Contact me if you are interested.
I also have a few sets of factory seconds available.
[email protected]
149.95 + shipping
factory seconds, 125.00 free shipping to the lower 48 of the USA
 
holiday special

$125.00 Holiday special on my horizontal stabilizer tip kit while supplies last.
The special will also include free shipping to the lower 48 of the USA.
 
Aerodynamic benefit?

Today I worked on the stabilator tips which I purchased from Clint.
I am quite impressed how nicely the tips fit to the contour of the stabilator ends.
However, on the bottom side near the trailing edge some additional work will be required for a perfect fit. Sanding will not be sufficient, it's more that the tips needs to be squeezed a bit together in the last 2 inches towards the trailing edge.

I also haven't drilled the mounting holes yet into the stabilator ribs, so I still have the option wether to finally install the tips or not. The additional weight including J-nuts and fasteners is 2lb and 3oz which is not quite zero and it is a long arm from CG.

What I am wondering is the aerodynamic effect to them, if there is one at all.
So I am looking forward for some opinions of you, the aerodynamic experts out there. Dou you think the tips are for any good in terms of aerodynamic efficiency.

Thanks a lot.

2lzytw.jpg
 
No aerodynamic expert here. I think they look great, doubt whether they will add any speed, and had the same fit issue you found. I eventually decided not to install them because I wasn't comfortable with the not-insignificant extra weight on the all-flying stab. However, there are lots of people happily flying with them, so maybe I was worried about nothing. Wouldn't be the first time, and they do look nice.
 
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If I calculated correctly, 2.2 pounds added to the stabilator will have the same
affect on aircraft balance as 4.6 pounds in the baggage compartment.
That affect can be mitigated by eating a few more $100 hamburgers. :D
 
If I calculated correctly, 2.2 pounds added to the stabilator will have the same
affect on aircraft balance as 4.6 pounds in the baggage compartment.
That affect can be mitigated by eating a few more $100 hamburgers. :D

Good thinking Joe, but then I might be forced to reduce my fuel load to compensate for the total load increase, and not be able to get home from the last hamburger stop. :D
 
How accurate are your scales for the empty weight calculation? Look at the error margin in the original CG calculation and see if this is noise level.
 
Bumping an old thread, but these tips look SO tempting to me I may not be able to control myself and get a set (if they're still available).

My plane is an SLSA so I'll need to check with Vans first as well.
 
performance

Actually, would be interested in hearing from people flying with the tips which we have on our RV12...our test pilot, who has built and flown six RV12s, does not like them as he says they make the airplane tail heavy and the stab more wobbly. Has anyone else noticed any changes? What is your configuration when you fly (single pilot, full fuel, baggage??)?
 
...he says they make the airplane tail heavy and the stab more wobbly...

That statement strikes me as one begging further discussion. I for one would really like to hear more, such as what is meant by "more wobbly?" Indeed, MORE than...? Can you please elaborate? Are there CG numbers to support the tail heavy condition?
 
Bad choice of word. The airplane undulates, up and down, not to lose control, but noticeable. All the other RV12 he has built and flown do not do that. The stick does not always stay in place during flight as with the other airplanes. The stab has a noticeable drop when you try to place in neutral position on the ground.
 
Bad choice of word. The airplane undulates, up and down, not to lose control, but noticeable. All the other RV12 he has built and flown do not do that. The stick does not always stay in place during flight as with the other airplanes. The stab has a noticeable drop when you try to place in neutral position on the ground.

I find this interesting.....can not see how these tips could cause this...I would be looking for rigging issues (I haven't put them on mine); but they look cool.
 
The tips unbalance the stabilator. Without the tips the stab will stay put when positioned. With the tips, the stab wants to droop down at the rear on the ones that I have looked at.

Van's has carefully balanced the flight controls, when you change them you become a "test pilot" as has been said many times before.

Personally, I love the feel of the controls and like the looks of my stock tips. After all, it's a more like a Porsche 912 than a 911.

Just my 2? of course, not an aero. :) Many will disagree.
 
Just an opinion

I have them on my 12 from the first time she flew and have flown multiple stock 12s and don't notice a difference.
 
Oh, now I get it.

Bad choice of word. The airplane undulates, up and down, not to lose control, but noticeable. All the other RV12 he has built and flown do not do that. The stick does not always stay in place during flight as with the other airplanes. The stab has a noticeable drop when you try to place in neutral position on the ground.

My control stick always falls forward at rest on the ground and I though this was normal as I have 160 hrs on now the the airplane flys great. I do notice a little (very little) tendency for the stab to oscillate when in turbulent air.

While helping a friend get his 12 ready for first flight I noticed his stick would park wherever you left it when moved. Mine always fell forward. How odd. I then check several other E & SLSA's and found that they too would park wherever placed. Now I was worried that something was wrong with mine.

I talked to Van's rep at OSH and they didn't have much to offer. Said it may be due to variations in balance weights for the stab but if it flys ok then don't worry about it.

I have had painted tips on my stab from day one and from this thread it appears that it adds weight to the rear and thus unbalances the stab. I'm going to have to rethink this and perhaps add some balance weight to offset unbalance. Going to contact Van's and see if they will weigh in on this.

Bill
 
igloj7.jpg


The balance of the stabilator is relative to where the hinge point is.
Note that 2/3's to 3/4's of the tip is aft of where the hinge point is.
That is going to add most of the tip weight to the aft portion of the stabilator and change the static balance.

I don't know how much these tip fairings weight so I don't know if the change in balance is an issue or not.

One consolation is that the stabilator is actually over balanced slightly with the standard balance weight supplied in the kit. If you disconnect the cables it will swing trailing edge up.
The reason it seems balanced with the cables connected is that the control column has mass and the hinge point of the control column is at the rear. So with the airplane at rest, the mass of the control column and sticks is attempting to swing forward, while the extra mass of the stabilator balance weight counters it trying to swing the sticks aft. The result is a closed loop system that as a whole is balanced.

The common opinion is that the balance of the movable control surface on its own is the primary concern. So, on RV-12's with stabilator tips installed, if the stab is balanced or still slightly nose heavy with the cables disconnected, it is probably still ok.

Disclaimer - The standard design of the RV-12 was flutter tested to prove a good margin of safety beyond VNE. Any modification (including adding stabilator tips) could have negatively altered the airplane so keep in mind that my statement above is just a personal opinion and until the flight test was repeated to prove it, the opinion is worth what you paid for it.
Anyone making modifications to the flight control system on an RV-12 must realize they are truly experimenting.

I personally would not casually add parts to a flight control system component without careful consideration of all the ways it might have an influence and at the very least confirming that it has not become negatively balanced.

Side comment - Even if changing the balance with the addition of stab tip fairings doesn't adversely effect the flutter margin, it could still change the pitch control feel slightly because you have altered the relationship of the control surface inertia vs the opposing force of the antiservo tab. Probably not enough to effect it in a negative way, but very possibly enough to notice a difference.
 
Thanks Scott for weighing in on this subject with your "balanced" opinion. You do bring up some very important considerations. Would you care to comment, with your personal opinion, on the subject of rebalancing the stab by the use of a few washers mounted to the nose of the outboard rib? I'm sure a very small amount of weight added to the counter weight arm would also accomplish this at considerable labor since you'd have to pull the stab for access.

I really like the finished look of the stab tips and would hate to have to pull them off having notice no adverse effects coming within 10 knots of Vne. But then, as you have pointed out I have noticed some stick oscillation (maybe 1/4 inch) fore and aft in rough air. This may just be a characteristic of a flying stab which I have very little experience with before the 12. The perils of being a test pilot.

Bill
 
Slow day at the hanger, so I pulled one of the stab tips to check the static balance point and to see what it would take to have the balance match the hinge rotation line.

Tip = 31" long
Static balance point is 13.5" aft of the leading edge
Stabilator hinge rotation line is 8" aft of the leading edge
2oz of weight just aft of the forward most attachment hole will move the tip static balance point to 8" aft of the leading edge. I used two 1oz self stick wheel weights. Could probably use a bit less if the weight is added directly behind the leading edge curve.

John Salak
RV-12 N896HS
120116
 
This got my interest up, so I tried out the theory at the hangar. Mine stays in any position I put it! To be truthful I think the autopilot servo is providing enough resistance to keep it wherever I put it;
igloj7.jpg


The balance of the stabilator is relative to where the hinge point is.
Note that 2/3's to 3/4's of the tip is aft of where the hinge point is.
That is going to add most of the tip weight to the aft portion of the stabilator and change the static balance.

I don't know how much these tip fairings weight so I don't know if the change in balance is an issue or not.

One consolation is that the stabilator is actually over balanced slightly with the standard balance weight supplied in the kit. If you disconnect the cables it will swing trailing edge up.
The reason it seems balanced with the cables connected is that the control column has mass and the hinge point of the control column is at the rear. So with the airplane at rest, the mass of the control column and sticks is attempting to swing forward, while the extra mass of the stabilator balance weight counters it trying to swing the sticks aft. The result is a closed loop system that as a whole is balanced.

The common opinion is that the balance of the movable control surface on its own is the primary concern. So, on RV-12's with stabilator tips installed, if the stab is balanced or still slightly nose heavy with the cables disconnected, it is probably still ok.

Disclaimer - The standard design of the RV-12 was flutter tested to prove a good margin of safety beyond VNE. Any modification (including adding stabilator tips) could have negatively altered the airplane so keep in mind that my statement above is just a personal opinion and until the flight test was repeated to prove it, the opinion is worth what you paid for it.
Anyone making modifications to the flight control system on an RV-12 must realize they are truly experimenting.

I personally would not casually add parts to a flight control system component without careful consideration of all the ways it might have an influence and at the very least confirming that it has not become negatively balanced.

Side comment - Even if changing the balance with the addition of stab tip fairings doesn't adversely effect the flutter margin, it could still change the pitch control feel slightly because you have altered the relationship of the control surface inertia vs the opposing force of the antiservo tab. Probably not enough to effect it in a negative way, but very possibly enough to notice a difference.
 
This got my interest up, so I tried out the theory at the hangar. Mine stays in any position I put it! To be truthful I think the autopilot servo is providing enough resistance to keep it wherever I put it;

It could also be that (contrary to what the KAI cautions about) you have a lot of friction in the pivot bearings for the control column (or any number of other reasons).
That is why I recommended that any check be to evaluate the degree of balance with the cables disconnected.
 
Paint

This will be different with paint
There is more paint on one side off the balance point

Joe Dallas
 
I own an SLSA, and haven't built a 12, but i THINK the autopilot only controls the trim tab on the FF stabilator.




This got my interest up, so I tried out the theory at the hangar. Mine stays in any position I put it! To be truthful I think the autopilot servo is providing enough resistance to keep it wherever I put it;
 
I own an SLSA, and haven't built a 12, but i THINK the autopilot only controls the trim tab on the FF stabilator.

Nope.

The pitch servo is connected directly to the control column that your sticks are bolted too.

BTW, the primary purpose of the tab on the back of the stabilator is as an anti-servo tab.
By making its attach mechanism adjustable, it also does the job (secondary) of a pitch trim tab.
 
I stand corrected.

Thanks for the information.

I'm amazed at how small the servos are, for a full scale plane I expected substantial servos, but they are no bigger than the model plane servos I use in my model planes.

During my demonstration test flight, before buying mine, while in autopilot, I felt the servo bumping back against my control inputs when it was on, and it was explained to me that that was the autopilot.

Still though, such dinky little servos. Not sure if they even have metal gears in them. I know they make some burly model plane servos with metal gears that have huge power, but VAN's knows what they're doing, so I know they've specified the correct servos for the job.




Nope.

The pitch servo is connected directly to the control column that your sticks are bolted too.

BTW, the primary purpose of the tab on the back of the stabilator is as an anti-servo tab.
By making its attach mechanism adjustable, it also does the job (secondary) of a pitch trim tab.
 
I stand corrected.

Thanks for the information.

I'm amazed at how small the servos are, for a full scale plane I expected substantial servos, but they are no bigger than the model plane servos I use in my model planes.

During my demonstration test flight, before buying mine, while in autopilot, I felt the servo bumping back against my control inputs when it was on, and it was explained to me that that was the autopilot.

Still though, such dinky little servos. Not sure if they even have metal gears in them. I know they make some burly model plane servos with metal gears that have huge power, but VAN's knows what they're doing, so I know they've specified the correct servos for the job.


You may be mistaking the trim servo in the tail for an autopilot servo. The Dynon or Garmin servos for the autopilot are quite "beefy" with a slipper clutch and all ... Even shear pins.

http://wiki.dynonavionics.com/Servo_Application_Guide


Some good info on the servos (Dynon) can be found here.
 
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