• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Supercub Thrust Line

Actually, all you have to do is step back from a stock supercub and look at how the spinner points down relative to the lines of the fuselage.

How come I never noticed this before, but now it sticks out like a sore thumb? :crazyeyes:
 
Thrustline

I've been amazed that Cub guys could keep this under their hats for over a year while Mark worked on his STC. It poped up a couple of time on the board and no one took the bait. I first heard about it in early April 03. Crash
 
Hi folks

Thanks to you Crash and all the others that helped me keep a lid on it. TJ--I appreciate that. Wayne and Jerry have been great help. They are schooling me!!

This post is just to get my email contact info out there. We have been overwhelmed with calls and I don't have time to deal with the calls as they come in. If you absolutely need info please email me and I will call you. Include your number, time zone and a good time to call. Our priority right now is to finish the paperwork--and get some before and after info from customers flying this product(VALDEZ). This will help you decide if it is a mod that is right for you. Thanks in advance for having patience with this start up.

mailto:akcub@mtaonline.net

Mark
 
At full (100 %) power cruise I need to step on the left pedal just a little. Is there a simple fix for this? I am trueing out at 127. Is anyboldy else aware of this with there plane?
 
Mark:
Glad to hear what you guys are doing.
Are you considering creating a replacement engine mount for the standard 150 hp cub as opposed to adding the extended lugs?
It looks as if a complete mount change would give a bit cleaner looking product and wouldn't have quite the "modified" look to it.
I am interested in how this works out as I may want to add it to the 18A rebuild that I am doing now.
Will this be approved for Floats?
Thanks and Congrats
 
NASA Study

ksecub said:
This might be an interesting read for you engineering type that are interested in thrust line angles:

http://www.dfrc.nasa.gov/DTRS/2000/PDF/H-2402.pdf

Some interesting reading. It looks like 0 degrees works best in some instances and 3.5 degrees worked better in other areas of the flight envelope, but then again this was done on a wide body jet transport. I wonder if that would translate over to a "Widebody" Super Cub??? :lol: Crash
 
Trim

94 Super. You tweak (bend) the vertical stabilizer to center the ball at your preferred cruise speed. Above and below that speed it will not be centered. :) Jerry.
 
Thanks. I should note that it does it at 2450 as well. Didn't mean to imply I fly around at full throttle. Has anyone put washers under the mount/engine to shim it slightly the left? "Tuning" the vertical stab sounds the easiest,
 
That negative thrust angle bugs the heck out of me to look at! Seems all backward. However, here's one possible advantage I'd be interested to hear others' thoughts on.

What has been experienced in terms of pitch response to power changes with the engine set to an increased thrust angle? I'm thinking that if the a/c were set up with a greater thrust angle it would pitch upward more for a given power increase than it would with a lesser thrust angle.

That would increase the stick work, and one of the nice things about cubs is their pitch balance in slow flight. So maybe one factor in the original engineering decision for thrust angle could have been to reduce the pitch response resulting from power changes, thus reducing pilot effort? In my 12, adding power in slow flight with full flaps requires a considerable increase in forward stick or trim. I would think that increasing the thrust angle would exaggerate that response?

So I wonder if a little bit of performance enhancement might also result in a trickier-to-fly a/c? I'd be very interested to learn what flight testing has shown in this regard. Also, since I'm in the middle of a major rebuild on my 12, I'd be very interested to learn whether this will be STC'd for 12's.

Gordon
 
Washers

94SUPER18 said:
Thanks. I should note that it does it at 2450 as well. Didn't mean to imply I fly around at full throttle. Has anyone put washers under the mount/engine to shim it slightly the left? "Tuning" the vertical stab sounds the easiest,

94SUPER18: Placing thrustline adjustment shims (washers) under the left or right engine mount blocks (thrust line left or right adjustment) works to get the plane to fly straight. I know of several planes that have this adjustment. You can only "tweak" the fin so much and get results. A trim tab on the rubber stciks out like a sore thumb. This is a good alternative. Crash
 
wing wash?

A lot of talk about rudder trim tabs and tweaking the vert stab and shimming the engine mount .....Rigging the plane includes setting the individual wing wash-in/wash-out ..Haven't heard much about that here. Very interesting topic......Red Jonson
 
I think we all see other pilots perform a maneuver, or perform a short take-off, and attribute the performance to the plane. I'm as guilty as anyone. I hope Mark's mod is absolutely the best thing since sliced bread, and I hope he's successful on the business side of things, too. But, the most important mod in any plane is still a good pilot. And for the most part, you can't go out and buy that mod.

I consider myself a skilled pilot. I have friends that are gifted pilots. There's a difference. They have natural abilities that I have to work to aquire. And still, they're better. I can buy a mod to narrow the gap. At least until they buy the same mod.

Good luck Mark. This is exciting stuff. I hope your investment realizes a return.
SB
 
That's note worthy. Kind a gives us stock cub guys a second wind. Your dad probably said to you at one time in your life "you don't need all that fangled dohickys" and then he goes and proves it. Nothen worse. How much more do tundra's weigh than 8.00 4's. Is that the 100 lbs. difference. But it does prove that weight is very relative to performance.
 
The rudder trim set up that Steves Aircraft sells for the shortwings looks like a nice set up, but I don't think the STC covers a PA-18 but if you're exp. it might be the way to go.
 
Thrust Line

Hi Geezer. I think everyone passed by your post. But I also think you missed a page. The thrustline mod simply adjusts the thrustline to zero plus or minus a tad. Just reread the info and I think you can relax. :D Jerry.
 
I have a question. If a Husky has a zero degree thrust line can I use a husky engine mount on an experimental cub project? Is the firewall bolt pattern the same?
Mike
 
The Husky mount is for a Dynafocal mount O-360 and is a little longer. It doesn't swing like a SC. I don't believe a Husky mount will bolt up to a Super Cub.
 
PA18 thrustline

So far there has not been any mention of cost for the motor mount lugs, extensions for the lower cowling, and stc paperwork. Anybody know how much?
 
diggler said:
Im looking forward to your performance testing results. My dad flew in yesterday to visit with his stock 1975 Super Cub. Its exactly as it came from the factory with 800X4 tires except hes on his 3rd 160 hp engine and uses a 7455 prop. We had a take off/climb contest against my cub with borer prop, vgs, tundra tire etc cub . He could take off shorter, out climb me and out run me. The 75 cub is around 100 lbs lighter than mine. Only thing I could do is land shorter. Maybe I need thrust line modification so I can compete with a stock cub. :eek:

Maybe you should ask him for some flying lessons :eek: Crash
 
I have flown the cub with the centerline thrust mod. I was impressed with the speed increase. I am not able to comment on the other performance features as I have not flown a cub a lot in the last few years. However I see a couple of questions about visibility. To me it was not a problem at all. The cub I was driving had big tires and extended gear.
The question I am curious about is the cyl head and oil temp. I would guess that there would be a decrease in both because of the increased area between the bottom of the cowl and firewall, and the increased airspeed. I would like to know if anyone has done a before and after check on the temperatures. Thanks
 
Back
Top