Ever used them?

I use them in bed.

You may want to elaborate on the request a little.

On full size craft boost tabs are used to allow the poor human pilot to move surfaces that are considerably larger than they could move otherwise. Models do not have this issue since the servo is more than adequite to handle the job. Bigger models just use bigger or more powerful servos. It's not an issue.

Yes, boost tabs could be used to allow smaller and weaker servos to move big surfaces but then the hinges would need to be better engineered and the surfaces would need to be mass ballanced to locate their CG's right on the hinge line or bad things would happen.

All in all no, you won't see boost tabs on models other than maybe scale models were they would be faked with a suitable linkage while the surface itself would still just be moved with a servo.

I have used boost tabs on both rudder and elevator on large models. This was before the more powerful servos were readily available. I found them very useful. I also found that the area of the boost tab should NOT exceed 10% of the area of the moveable surface else the boost tab may overpower the servo in some instances. All my experiences with boost tabs has been very rewarding and let weak servos (compared to modern ones) do a very effective job of giving adequate authority to large control surfaces.

Ever been to a Turkish prision.

I have not used these devices but have read some stuff on them and have been intrigued by the potential. The main thing that stopped me was the likely delta in performance between typical speed and landing speed. Any issues in effectiveness between normal and landing speeds?

They <font size="4" color="#ff0000">SUCK <font size="2" color="#000000">just like RCU!</font> <font size="2" color="#000000">Boost Tabs are the stupidest thing I've ever heard of ! Only a Idiot would fly a plane using cheap ass nylon gear servos on a plane with Boost Tabs!</font></font>

I did not notice any difference. One thing I should have also said was that it is important to also static balance your moveable surfaces, especially elevator and ailerons, to take the static load created by G forces off the servos and to prevent any hi G manuvers from over riding your servo power.

i modded an ultrasport kit to have boost tabs on rudder and elev... im almost done covering it.....hopefully itll fly nice

Here is a link to some interesting information regarding boost tabs,

http://web.archive.org/web/200502121...oost-tabs.html

Thanks for the link iron eagle, the content jibes with my experiences with boost tabs very well.

Rodney I too have used them for both large surfaces and small, when a powerful servo was not an option, with much the same results as you. As long as you are mindful of the weight of your setup they can be a real plus.
But what do I know I have used trim tabs as well...
As far as the question regarding low speed operation they seem to work just fine, up until the control surface itself loses effectiveness.

I put a Hitec HS 55 on my 40% rudder on the boost tab and I have had the best rudder authority ever!

This is the one I'd really like to see a photo of!

Very educational thread for me.....

These are the tabs I use on a 1/4 scale Corby Starlett. Didn't know how much throw to use so I gradually moved in on the tab horn. When I hit the magic spot, it was like I put the next size bigger servo in it.

Yep I'm working on 40%r with a DLE111on it that should be around30lbs and I chose to use HS-56HBswithBoost Tabs on all the surfaces.......

Very nice. Using the smaller servos should save ya some weight also. I was thinking putting a smaller servo on the throttle but decided I would throw in the new Hitec servo with 600 oz of torque.

wobblewobble, Brandon15

you two guys are the only modelers to mention building boost tabs into their models. Could you two grace us with pictures?

Here is one that worked for me.

Hi,

Iron Eagle mentioned a good discussion about boost tabs and trim tabs in this section of the site, well i'm looking to add either one of these types on the rudders and elevators on my Constellation model.

http://www.rcuniverse.com/forum/m_45...page_40/tm.htm
Go to bottom on this link to see posts regarding it.

My reason is same as few have mentioned in this thread already, i want to use 3 mini MG servos, 1 on each rudder on this model, now problem is that i can't find a servos in this size that will do the job w/out addition of tabs, so what do u guys suggest.
Out board rudders surface area is equivalent to LT-40 rudder and center one is less....

Why metal gear? Added weight and they don't wear as well. Good for shock loads, say as a steering servo, but I wouldn't see them as needed/wanted for a flight surface. I'd run the numbers through a servo calculator to confirm, but off the top of my head I'd say a Hitec HS65 or equivalent. Karbonite gears wear well, last a long time. They handle the torque load just fine that the servo can dish out, and they don't have a high amp draw for their power. FYI, there are some killer thin-wing servos you may want to look at as well here: http://www.espritmodel.com/index.asp...arch=GO&Page=1
or if you don't want the high current of the digital; http://www.servocity.com/html/hs-125mg_slim-wing.html ironically only available with metal gears.

Thanks Max for the links, Esprit Models has sweet range of thin wing servos n they do have good torque ranges also. Let say i get 3 of these servos, then would i have to balance the rudders on hinge line also or could i get away with doing that?

I'm also trying to come up with simple mechanical solution to this issue also, let see how it turns out on the paper first n then on the model itself.

you might not want to go with Servocity, the seam to list three thicknesses for that servo, .51", .39" and 10mm (.394") (probably 10mm because everyone else is)