Thrustline, Steve Tubbs, Strakes vs VG's on SC's

[GeneHerzog]

I recently asked Mark at Thrustline to sell me a TL kit and he insisted I call Steve Tubbs with Performance Air first to get a report on the results he has had with the Smith kit and TL. What a great experience! Steve told me everything I could want to know about his results using the TL mod and said EVERY SC KIT HE SELLS OR BUILDS NOW HAS THE TL MOD AS A PART OF THE KIT. ITS NOT AN OPTION ! That alone sold me on the Thrust Line mod and I ordered it from Mark yesterday.

Steve also said that the VG kit with the strake is better in his opinion than the Micro Vision kit which I already have. He explained that the strake is much more effective than the VGs on the bottom of the Horz Stab in the SC. Any comments from anyone with experience with which works best for them??

I was also impressed with the merits of the exhaust system from Steve. Would like any comments on this also.
[/u]

 

[sj]

Steve also said that the VG kit with the strake is better in his opinion than the Micro Vision kit which I already have. He explained that the strake is much more effective than the VGs on the bottom of the Horz Stab in the SC. Any comments from anyone with experience with which works best for them??
[/u]

Gene, this is just my personal opinion after owing and flying both (and currently having the strakes on my plane). I prefer the Micros, but it may have more to do with how they are placed on the leading edge than what is happening on the tail. Early Micros did not come with the under stab VG's and you defintely would see a difference without those. I will admit that I have flown many many different supercubs and other planes with micros, but only a few (and all have been fairly heavy) with BLRs. I guess the bottom line is that the differences I feel between the two are not enough to get me to take the BLR's off and put on Micros, or vice versa so both are pretty darn good products, and one is quite a bit cheaper.

sj

 

[Steve Pierce]

Jerry Burr discussed this topic several years ago and it made sence to me. You might try a search and read what he wrote.

Gene, What ever happened with the MT prop?

 

[gdafoe]

Gene, is there something different about the Smith Cub that makes the TL mod more effective or different in Steve's opinion? And how does the strake perform different on the Smith Cub. There has been lots and lots of discussion here about the Micro vs. BLR. Are the results different with the Smith Cub for all these mods? Also how is Steve Tubb's exhaust better. I saw one on a Smith Cub that was nearing completion in Michigan last summer and was impressed that I'd sure rather have the Sutton Exhaust on my Smith Cub, I have the Sutton on the Cub I fly now and it makes for a better, more funtional installation than anything I've seen (IMHO).

 

[Bill Rusk]

Gene , Gerald and others

I have been to Steve Tubbs shop a couple of times and I was most impressed. The man knows of what he speaks; however, he also tweaks the kit a fair amount. If I had a lot of money I would just pay him to build me a Smith Cub. His are in a class way beyond anything I am capable of. He makes so many subtle changes that it is hard to keep up with them all. This would probably affect the performance somewhat and in concert that might allow the BLR system to outperform the VG's in this "one isolated case". For example, he cuts the rear horizontal stab mount off and rewelds a taller one in its place, effectively changing the tail AOI.
Even if the BLR system knocked off a couple of knots off the stall I would not use it because I find that big old strake just gets in the way. Just my opinion.
If Steve says his exhaust works better I am sure it does. He has spent time at Lycon using their Dyno. But like the airframe, he modifies the engines he builds and the exhaust works on "his" engines. I don't know if it would work as well on a stock engine. Steve would know. Sometimes mods can cancel each other out and sometimes they can work synergistically.

Smart guy and a great resource.

Bill

 

[gdafoe]

"he cuts the rear horizontal stab mount off and rewelds a taller one in its place, effectively changing the tail AOI"

I must be missing something. That is what the trim system does, isn't the SC's ability to change the stabilizer AOI one of the reasons that the SuperCub is great airplane??

 

[Bill Rusk]

Yes, that is one of the things that gives the cub such a wide working envelope. Steve adjusts the neutral point, thereby changing the amount of trim available in a given direction.

Bill

 

[GeneHerzog]

Steve P,
I never got any answers from the MT people at Sun and Fun or otherwise. This was after many attempts. I gave up, ordered an 80x46 wood/composite from Sensenich and already have it in my hangar. So much for MT. Great product, poor marketing.

Steve J,
I think I will do what you suggest and just stick with the Micros I have now. I was thinking about having a hybrid and use the Micros with the Strake from Tubbs.

Gerald,
Tubbs just says that for some engines (I am putting a roller lifter 180 Superior on mine) that his exhaust may pick up as much as 8 to 10 hp or more, it the "tuning matches your engine. He seemed to think it would really help mine. I have to echo what Bill says about the mods and suggest you call Tubbs for an specific questions.

THANKS FOR THE INPUT. I WILL KEEP LOOKING AT THIS POST FOR ANY OTHER ADVICE RE THESE ISSUES.

Anyone else going to Sentimental Journey?? We are going with the Legend Cub guys here in Sulphur Springs and are taking six Legends up including 4 customer planes the owners have flown down to go up with us.

I AM REALLY SOLD ON THE THRUSTLINE MOD AFTER TALKING TO TUBBS AND MARK!! MARK MADE A BIG POINT OF HELPING ME GET THE TRIM AND ANGLES RIGHT WHEN I AM READY TO PUT IT ON. CANT GET BETTER SERVICE THAN THAT.

 

[gdafoe]

Are we talking about the exhaust that he sells made by Custom Aircraft Parts in El Cajon, CA? That is the one I saw and I don't think it is a tuned system.

 

[Jerry Burr]

Strakes

Using a raised rear horizontal stab mount is the only practical way to counter the negative effects of the strake. The ability of the tail to stall the airplane is lessened by the installation of the strake. (The idea) That ability is replaced by the increased AOA of the tail. Makes perfect sense. Jerry.

 

[Homerrhoid]

I've had micro VGs for 4 years or so- I've never run out of elevator control or authority. From my perspective they work just fine.

I did have trouble with knocking a few VGs off from flying gravel/snow, so I put a dollar patch of fabric over each VG and there they stay. Problem solved.

 

[Shaun T]

I just wanted to clear up what I have learned from both. First of all I am a newbie but I know Performance air quite well. In fact this is my first post here. The BLR vg's are preferable not only because of the strake but also because of the postion of the vg's on the wing. They are staggered so that as the wing loses it's lift you will still have ailerion athourity in a stall. The forward mounted vg's by BLR are in the same location as the micro system. I have noticed no stall speed difference beetween the two. Also the Blr vg's are taller. They make more of a vortex. The main reason performance air likes the strake is not because it keeps air attached to the elevator but it creates a vortex that keeps air attached to the rudder. After installing vg's the tail know stalls first. To over come that Performance air is installing tail tape to close the gap between the elevator and the horizontal stabilizer. After installing that you will then stall the wing first but with ailerion control.

 

[willyb]

Thrustline,Steve Tubbs

Hey Gene, count Iris and I in on the Lockhaven trip.Flying to Sulphur the week prior to visit with all of you.Look forward to getting together and getting a ride in your cub. Bill

 

[Dave Calkins]

Jerry Burr, anything else to add?

 

[JimC]

I'd rather see the tail underside vg's mounted near the front of the tail rather than the elevator hinge line.

 

[Jerry Burr]

Stuff

Hi Dave. Nothing that I haven't said before. I talked to Steve and his feedback was that the BLR was better than Micro on approach. Probably is. Micro was designed to be used with full flaps and some power for takeoff and landing. I never considered approach, and wouldn't have built for it anyway.
Hi Jim C. Do you have a copy of my spin video? It shows why the tail V.G.'s are where they are. More relative wind velocity there. And a vortex is only about 16" long anyway. Wouldn't last long enough to go around the corner. Jerry.
P.S. Where the relative wind is equal the large and small V.G.'s produce the same vortex. If the big ones were better I would have used them. Wing covers were also a consideration.

 

[S2D]

They are staggered so that as the wing loses it's lift you will still have ailerion athourity in a stall.

Isn't thaty what washout is for?? Does that mean you get to remove the washout on the wings when you install the BLR vg's??

 

[JimC]

>Hi Jim C. Do you have a copy of my spin video? It shows why the tail V.G.'s are where they are. More relative wind velocity there. And a vortex is only about 16" long anyway.<

Hi, Jerry. first, don't give up on me on that prop -- my prop box had been eaten by termites, so I'm building another.

No, I don't have a copy of the spin video. Would love to see it, how do I go about getting one? Re vortex length, that depends upon both height and chord of the vg's. It can be quite long if the vg's stick up about 20% of their height through the boundary layer. For example, the vortices from Art Mattson's Cherokee vg's extend aftward roughly 60 inches, but they are pretty tall and have a wide chord as well.

Has anyone tried sawtooth tape just below the center of the leading edge radius on the tail?

 

[CPT. BLY]

When I installed my Micros, I had a long talk with the gang at Micro in Anchorites 8 years ago. I was told that the farther forward the VGs are the more effective they are for slow flight.
The VGs were first used I was told on the Boeing B-47. Since then all Boeing jets have used them. On the big jet there placement on the wing starts about one third back from the leading edge and they do sweep back faster then the sweep wing dose. These are high speed wing and they are working on boundary layer air sticking to the wings at high speed and high altitude were there is little air.
I flew Lear 25Ds, and there are four different wings for the Lear 25. Really the wings are the same. Four different companys trying to make money, came up with there own ways to disturb the boundary layer air.
The Super Cub was designed along time ago and Piper Aircraft Co. never changed a thing. Some mods are good and some are just a copys to make money. Changing the thrustline or putting on strakes or bolting on bigger engines or changing the exhaust system. If all these things where better than stock, Piper would have changed them. Just like Cessna did with the straight tail 172 thru the Hawk XP and Cutless RG line.
Just My Extreme Right Wing Opinion.

 

[Cubus Maximus]

Cappy,
I used to think that but am figuring out that sometimes companies just do it one way 'cause that's the way they've always done it. It works good, you feel it's about as far as you want to take it and the industry is leaving that particular technology behind - so why change it?
It costs cash money to develop a product further and development revenues are going into new products that make more money for hopefully less production cost. Why revisit the past? That's were inovators can find a niche.

Wha-la:

Thrustline mods and belly pods!

Brakes that stop and Borer props!

4 inches fatter, if you're large - it matters!

Tundra Tires like donuts and lightweight engine components!

Heavy duty 3 inch gear and with safety cables, a little less fear!

Scott tailwheels - mucho' better than stock...
remove the header tanks and make Boz squawk!

Exhaust systems, everybody makes 'em, keeps the flame tube from blocking, and increases rpm!

Okay okay, so that was pathetic :roll:

 

[PA-18]

I have been interested in the thrustline,just to lazy too try.

After all if my Pa-18 flew any better than it does at slow speed now, I'd probably get in trouble. BLR user and advocate. 82" 44" prop a must have. These are the only things that I feel have made mine a better preformer,and the fact its a lot lighter now since rebuild from stock. Thats an honest 1700hrs worth of Pa-18 time in my bird. All of which was going no place just looking around seeing where I could land. Hunt'n fishn'n and farming.

Oh yeah I almost forgot,don't let anyone kid you a light weight cub will out perform anything you can buy to put on one. If you argue this point then you prove mine.

 

[CPT. BLY]

Hay 18
I agree with you on your P.S.
My wheel cubs a 1958 150HP 82"/41 borer prop, micro VGs, FAD safety cables, airglass cargo pod, 26' goodyears. And I take off shorter than 200hp Cubs. I flew with them all last summer and they were pissed.

 

[Jerry Burr]

Stuff

Hi Cpt.Bly. You may find it interesting that V.G.'s were first used inside of steam pipes on ships between the boilers and engines. That was to speed the steam up. The V.G.'s you refer to on top of the Boeing wings are there to slow down the air over the wing and let them cruise at a higher mach #. Our use is closer to the steam pipes. Jerry B

 

[CPT. BLY]

HI Jerry Burr
I don't know about boilers but I will agree we are working on the slow end of the curve. That is why Micro puts there VGs so far forward. This is where the high pressure air would be moving the fastest.

 

[redrooster]

Hey Maximus, nice job with the poetry, I liked it. See where you can go with this one: "there was a man from Nantucket....."
JimC: I read a magazine article a while back about using a piece of PVC pipe to ship a prop in,instead of building a prop-box. Seemed like a sound idea,with 2 endcaps & some padding it'd be at least as skookum as most any box you would build. Quick,easy, and cheap to boot.

Rooster ( i AM the man from Nantucket...)

 

[Cubus Maximus]

There once was a man from Nantucket (living in WA?)
at short landing events - he stuck it!

 

[tempdoug]

I wonder how our delivery service would look at that size pipe in the mail? doug

 

[bob turner]

I regularly fly stock Super Cubs with 100 and 160 HP, and also the Micro and BLR VGs on 150 and 160 cubs. I am not good enough to tell the difference, except it seems like the 150 Cub with Micros is slower along the ground when in the flare. It also has flaps 60.

All of them stop just fine, when measured from the threshold, and all seem to leap off the ground from a 3-point attitude. I have not yet flown the thrustline, and am just getting acquainted with the Charlie Center wing. My initial impression of that is that you can get so slow the ailerons have little air across them.

I have no need to push a Cub to its limits, so I don't. But we do have a marked-off landing area, and I have the skill to plant the tailwheel within inches of the beginning of the marked area.

 

[redrooster]

The prop-in-a-pipe article was about shipping a fixed-pitch prop. Size seems like it'd be comparable to a wooden box or crate. It'd have to be a pretty damn big diameter pipe to fit a c/s prop, better stick with a box for that. Can't see that any shipping outfit would have more trouble with a pipe as opposed to a similarly-sized crate. Maybe fasten the pipe to a board so it have a flat surface to lay on, as not to roll around.

Rooster