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Lowrider LSA

That's very nice article about the Luscombe...they are a neat old airplane.

Their bend is cleaner than I had planned and the flapper will be right at home on the end.

Just a point of interest...0.016 2024 is a bitch to bend into a "C" for the rear spar flange. I tried to use some 7/8" tube to bend it around...no joy. Maybe my resident IA has a magic tool to do a smooth roll.
 
Don't know what you have for a brake. Mine is a 4 footer. I've made large radius bends by making a series of very small 2-3 degree bends. Space these bends between 1/16 - 1/8" apart. You will be able to see a series of very small lines at each bend but for this purpose it should be very satisfactory. Start with the entire piece of metal clamped in the brake. Make the top bend first. Then pull the piece out of the brake clamp 1/16 - 1/8" to make the next bend, etc. Make the final bend leaving enough flat to fasten to the spar flange. You can always tweak it by hand.

That Luscombe picture doesn't show the static ports. It might be a good idea to clamp a static tube next to the pitot tube. It will be easier to "tune" the static ports if it is out away from the effects of the fuselage.
 
I have a 3' but have ready access to a 6' so I'll give it a try and see if I can get it down to 3/4" or so...actually the spaces between the hinges are less than 3' anyway.

I'm guessing the bottom of the wing is where you are meaning for the static port to go so it is in lower pressure air and keep it away from prop disturbed air?
 
Sky,

While looking at the Luscombe pictures, I was reminded of the "ribbed" trailing edge method used widely by production planes and was wondering if this method is stronger than a folded trailing edge or is it just to speed up production?
 
...I'm guessing the bottom of the wing is where you are meaning for the static port to go so it is in lower pressure air and keep it away from prop disturbed air?
15144b.jpg pitot_static_tube_2447.jpg A couple of examples. Instead of the "L" shape it could be straight coming out of the leading edge. The static (ambient) port wants to measure the static air pressure next to the plane without any influences.
Sky,
While looking at the Luscombe pictures, I was reminded of the "ribbed" trailing edge method used widely by production planes and was wondering if this method is stronger than a folded trailing edge or is it just to speed up production?
I believe that the "ribbed" trailing edges is just a method of cutting the number of parts, fewer ribs. For the home builder it is a lot of work, special tooling etc. Not impossible though it takes a longer sheet of metal.
 

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OK, side by side 1/4" alum tube with the static port on the side of one of them and the end plugged. Hole in the static side looks to be maybe 1/16" to start and I can increase as necessary. Straight out the leading edge bent down 10* then 10* up on the end with a flipper on the pitot side.

Thanks Sky!
 
Low, You are guessing at dimensions, locations and designs. You "may" guess correctly and you may not. A simple google search will bring up all sorts of pitot/static information.
This is a well known Kollsman pitot/static head. pitotStaticHead.jpg I measured one which I have. The pitot hole is 1/4". The static holes (3 top & 3 bottom) are #57 drill .043". The static holes are 3-1/2" aft of the pitot hole. I've flown two airplanes extensively with this head mounted on an aluminum tube projecting out of the leading edge of the wing. One of the two worked as you see it. The other required a band to be placed ahead of the static ports around the head to bias the static air flow. Why was this necessary? Don't know, but that is what worked.

Take a look at this: https://www.google.com/search?q=pit...u4DQCw&ved=0CB8QsAQ&biw=1366&bih=644#imgdii=_
Lots of ideas here. Do you still want to make your own? Reinvent the wheel?

The size, shape, location and quantity of the static openings are important. It is amazing how a large percentage of pilots and mechanics seem to take static ports for granted. An airspeed system isn't just an instrument with a tube sticking out in the breeze.
 

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Sky,

There is lots of info on the web and I don't want to reinvent anything...that's why I decided to order PITOT-STATIC TUBE #15144 from ACS rather than screw around trying to make one myself. It may or may not work well for my application but I thought I would give it a try. Now I need to know where on the underside of the wing it should be mounted.

Thanks for the above info you provided.

 
Low, You are guessing at dimensions, locations and designs. You "may" guess correctly and you may not. A simple google search will bring up all sorts of pitot/static information.
This is a well known Kollsman pitot/static head... View attachment 17220
Neat to see the inner designs of this head, I have purchased one for the Bearhawk project. It was super cool just opening and examining it and its packaging, having been sealed since its date of manufacture in 1944! Superb quality.
Mark J
 
Several votes for the jury strut but on the Riblett wing there is only one strut so no jury strut.

The location Sky used falls right next to a rib so the skin should be pretty stable with little vibration and I can easily put a diagonal stiffener in to brace the skin outboard of the rib making it a solid spot to mount the base of the pitot/static probe.
 
I'm adding this post I made on another thread for discussion purposes here and that I'm think of a trim change to a tab on the elevator.

I agree the aircraft speed is a big part of dealing with a trim failure. Using the jack screw has a lot of merit and has proven reliable for many years and maybe I'm too concerned with a way to make it failsafe.

The use of a trim tab allows it to just trail the elevator if the cable breaks but would still be a problem if the cable/pulley gets stuck in a pulley or something shifts in the cargo bay...that's the reason I'd like to use a teleflex type push/pull cable. I'm on the verge of abandoning the jack screw in favor of a trim tab for simplicity and probably some weight savings but mostly because it seems to be less vulnerable to runaway or getting stuck in a bad position...or maybe I'm wrong.
 
I'm adding this post I made on another thread for discussion purposes here and that I'm think of a trim change to a tab on the elevator.

Low check my response on the other thread.

This is another option: paddle_trim.jpg trim_paddle2.jpg The early Taylorcrafts used this method as well as the Fly Baby.
 

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Sky,

That's a simple solution but down low like that would pick up a lot of tall grass, mud, rocks and such...any way to put it above the horz stab and still have it work?

A trim tab on the elevator isn't much more complicated than the paddle and using the push/pull cable seems to me to take out all the bad things about using twisted cable and pulleys. I suppose there is a potential of the trim tab breaking loose in that system and causing flutter but a stainless rod in a Teflon lined sheath has got to be safer than twisted cable. The paddle certainly is dead simple...one push/pull cable to a lever mounted below the throttle on the left side and you have an easily adjusted trim system...trim tab just seems cleaner.
 
That wasn't meant to be a suggestion to try it, only an example of a completely different method. Aeroncas used a tab controlled by two pulling cables. The Swift and Seabee used a tab controlled by a screw jack. The Lake uses a separate hydraulically powered surface. Your method will also work if designed correctly, takeing into consideration allowances for bend radius and elevator motion.
 
You want simple and lite? Loop a bungee from the front seat frame around the front stick and back. Slide the bungee up the stick as the stick force gets heavier.

Glenn
 
Can't get much simpler than that Glenn and I have a lot of bungees!!

Sky,

I put a little bitty push/pull cable to replace the throttle cable on my big tractor and I think it's rate for 100lbs and you almost tie it in a knot and it still works. 3/16" should be plenty strong enough and it stays in the fuselage and operates a rod that moves the trim tab thru the horz stab to another arm that pushes the tab. The push/pull cable clamped in place inside the fuselage...don't have it completely thought out yet but I'll use small rod ends that I can adjust to get proper trim tab movement.

We put a 5 gal bucket full of over ripe plums and apples out for the deer last night and a little black bear (maybe 150lbs) ate them all...my Lab chased him off twice but they were all gone this morning.
 
A Ray Allen servo is light and simple, and runs off tiny, like 24 gauge I think, wires. RANS been using them for years with zero problems. Those teleflex cables are HEAVY.
 
Courier,

I think you suggested RAC trim system last time we discussed elevator trim. I'm not opposed to electric trim and it does seem to make sense with a trim tab, it's simple, effective and light...what's not to like. Same problem I had with the motor driven jack screw, if it fails you're stuck with the trim in the position where it died and you can't get it back to neutral while flying. Maybe that's not a big deal, especially if they don't usually fail.

I looked on their site and the likely servo is roughly 1 inch thick and I could make a fairing so it could be mounted in the elevator so it could drive the trim tab with only a single 5 conductor wire between the horz stab and the elevator and could be "armored" to protect the exposed portion. It only weighs 4 ounces so it would hardly be felt if it were mounted next to the hinge and the elevator will be balanced anyway. And the momentary use of the trim motor only pulls .8 amps while the trim tab is in transit...not too hard on a little battery. Cost...around $335 by the time all is said and done including wiring, switch and position indicator.

Thoughts anyone?
 
I think that it doesn't matter which trim system you have as far as the consequences of an in flight failure go. Whether its cables, wiring or teleflex, if they fail then its gonna make portions of your remaining flight uncomfortable. None of the above systems are completely failsafe.
Having said that I am in favor of a jack screw (stabilator) style trim vs a tab. Simply because I dont care for the increased induced drag and less effective elevator that are inherint in trim tab systems.
 
I'm going to disappoint both of you...I cut out a trim tab on my left elevator and I'm leaving the structure for the jack screw in place in the fuselage so I can "trim the horz stab" for the most effective location and hopefully reduce the majority of the drag in cruise and still allow the trim tab to function properly. Once I get the horz stab in an optimum location, I'll remove the heavy parts of the jackscrew and rely on the tab. I have an access panel to the jack screw area so that will allow easy access.

Only question is what drives the trim tab but twisted cable and pulleys are out the window.

Courier,

I weighed a 12' teleflex that I removed from my boat when I move the helm forward and it came out to 14 oz...so once I mount the box and add in a fairing I'm probably about 7 oz heavier than the RAC method and $275 cheaper using the teleflex cable.

Still thinking....
 
Haha Olibuilt has it right. You can try and try to re invent the wheel... But at the end you just have to pick what feels right to you and then maintain forward progress.
 
I'm going to disappoint both of you...I cut out a trim tab on my left elevator and I'm leaving the structure for the jack screw in place in the fuselage so I can "trim the horz stab" for the most effective location and hopefully reduce the majority of the drag in cruise and still allow the trim tab to function properly. Once I get the horz stab in an optimum location, I'll remove the heavy parts of the jackscrew and rely on the tab. I have an access panel to the jack screw area so that will allow easy access.



Courier,

.

I think If you fly a bunch of missions fast and slow and use one or the other to trim the tail and test each flight equally that you might have a different opinion in the end.

Glenn
 
You may be right Glenn. That's why I'm leaving the jack screw parts in place until I have a chance to fully evaulate the trim tab. If it sucks I can go back to the jack screw or depending upon the results, I may use Sky's paddles...whoda thought!
 
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