Pilot Report—Loni -–Cub pilot in the “Big Rocks and Long Props” video.

For Mark @ Thrustline, and all you other cubdrivers out there who have ever considered this mod!

For what it is worth, here is my take on it!

Simply stated, I love it! The Thrustline mod is by far, the most noticeable performance/safety enhancing mod that I have ever installed on my cub. The difference this mod made on my airplane is incredible! Here is what I found:

1. Increased stability behind the power curve (very noticeable in mechanical turbulence.

2. Increased cruise speed (4 to 5 mph in my case).

3. Improved stall characteristics (power on 3 mph).

4. Increased prop clearance (almost 3").

5. Increased angle of climb (much more stable at increased angle of attack).

6.Shorter take-offs - Allows you to rotate and fly a littler sooner in ground effect, less likely to settle back in on premature rotation. Note: if you do not have at least 31" tires and extended gear you will not see the full benefit of this (I.E. angle of attack).

There are too many benefits to this mod that I have found to list them all, but these are the most noticeable.

There are only 2 negatives to this mod that I have found, the first one being the loss of visibility over the nose prior to touch down upon landing.
The second one is the increase in R.P.M. required to lift the tail of the airplane with the brakes locked (about 200 R.P.M.).

The performance benefits of this mod are huge! After getting use to this mod it is very noticeable flying Supercubs without them.

Thanks Mark @ Thrustline

Fly Safe
 
Loni 749er/83Z            

If you ever wanted to see who uses the big tires try www.www.cubdriver749er.com

Pilot Report—Phil Mattison---180hp CubCrafters Cub

 I just flew my Cub Crafters 180 HP Cub with the new thrust line mod made by Mark Englerth. I flew it the first flight with the Sensenich 76EM8056 Prop. As Mark predicted I was not impressed with the results with this prop. Both before and after the Thrust Line mod I felt the Cub had poor take off and climb performance. But a good top end speed of about 110-MPH with the Whipair Hydraulic wheel Skis on.

Then Bob Timm from Seaplane Services removed the Cruise prop and replaced it with the McCauley IA200/FA8242 Climb prop. I was very impressed. My take off was very crisp and the climb was aggressive. My top end speed was now 108MPH only 2 MPH less than the cruise prop. I just could not believe it this airplane has always flown about 95MPH with that McCauley prop no matter what I did to it Floats, Skis, Wheels, It always flew about the same top end speed.

Tonight I got 108 MPH at full power, at 2450 RPM I got about 102 MPH, and at 2350 I was now back to 95 MPH and my fuel flow was down to 8.5 GPH. This is quite an improvement in top end speed and fuel flow.

Next I did a few approach to landing stalls with 2/3 flaps. My stall speed was down to about 33MPH. This is a lot slower than normal. I have also, within the last few flight hours added Vortex Generators. The combination of the two mods has reduced my stall speed 8 or 9 MPH.

I didn’t have much time to fly the plane tonight. I am very excited to go fly some more..

Philip Mattison
N902CC
Forest Lake MN

Pilot Report—Dave Hartman---160hp cub

Wayne Mackey and I started on my cub this morning at 8:00 am. We installed the TL mod and was pushing the cub out the door when I looked at my watch at 10:15 am. It went on very nice and easy with no problems with fit anywhere.
Before we put it on this morning I flew for a half hour getting some hard numbers to establish a preformance base. By the time I flew it after install the wind had come up to 10-15, so hard "after" numbers will follow but this cub, which is at the lower end of the AOI range was helped a bunch.
First thing I tried was flying with the mains just off at the slowest you can go. Before This cub felt heavy and tended to suddenly drop out from under you. With the thrustline both Wayne And I thought it was much more stable and easy to get to the very edge of a stall without loosing the wing. IF you did get it to slow just a touch of power and you were flying again. If you added the power needed to arrest a stall before the TL mod you were 15' and climbing right NOW.
I picked up some speed at 2500 RPM but it was to windy to tell exactly how much, seemed like 3-5mph. I also noticed that it will roll in and out of a hard turn quite a bit quicker and it seemed I could use more brake on landing before the tail would come up.

I picked up a bunch of rate of climb, 200'-250' fpm at full power and 60 IAS.

As soon as the wind goes down I will post hard numbers on all the before and after tests.

Dave

Pilot Report---M Hack---180hp CC cub on Amphibs

Finally got around to having the Thrustline mod installed on my CubCrafters amphib last week. Flew up to Big Lake and Mark measured my plane. Harder to measure because of my belly pod but the numbers did not seem favorable to Mark. I decided to take a chance and see if it would work. Mark has a great money back policy.
After the install and my testing I am very impressed with the increased performance.
I only gained 3 mph in cruise and full power speed but the TO and landing performance is notable. The plane now flies with wings level versus tail low before the mod. At 70 straight and level the former RPM was 2000 and now 1850. I gained 50 RPM at full power.
The plane feels a lot more solid at low speeds. I operate off a small lake in Alaska and pop off at 40mph with full flaps. Before the plane felt heavy (which it is) and now it wants to climb. Feels at least 200 lbs lighter.
Approach speeds have changed. Have to slow it down at least 10 mph slower or will get a float.
Gets on the step with more authority and accelerates faster on the step.
Am very happy with this mod and Mark and Fred at Big Lake did a great job on the installation.

Mike

Pilot Report---Steve T---160hp CC cub

OK ALL You CUB PEOPLE......About this mod.....I decided to try it on for size. My Cubcrafters PA18 160 ported and flowed by Lycon, 31 inch bushwheels, all the good stuff.....The skeptic in me says it all sounds to good to be true....I've got a lot of time in taildraggers and a fair amount in cubs.....so I wont bore you with all of the details....just a few words to sum it all up.....Holy cow.....You have to try it. My cub is faster and it is slower 14 MPH on the top and I haven't actually figured out how slow on the bottom...... before........ I'd drag it in behind the power curve, airspeed indicator pointing uselessly toward the heavens, just hanging there on the prop.....Then chop the power it drops on the whatever like an anvil and you have returned again unscathed. So when i try this familiar oft repeated maneuver post mod what happens when the throttle comes back to the stop............The airplane continues to fly unaided by gasoline for another 200 feet.....So in the ensuing touch and goes I am too chicken to fly slower but too short of time to go out and actually see what airspeed will result in a power on and power off stall....I will do that soon....but for now I can definitely say it is a bunch slower than it used to be.

Pilot Report---JM Fejes---160hp cub

Concerning the trust line mod.
I purchased the mod from Mark last week $1,800.00 plus $200.00 install. pa 18 160 hp stock wings w/vortex. My numbers where 34 stall, 94 mph at 2500 rpm, 80 mph @2250rpm ,70mph @ 2150 rpm.

after stall 31mph, 98 mph @2500rpm, 80mph@ 2100 rpm, 70 mph@2000 rpm .
Overall signifacant improvment in take preformance that also transfers over to short wheel landing capabiloties.. more so than stock configuration.
since the install I have flown appox. 30 hours to date.
I have several Cubs and will plan on doing the mod. to all three.

JMF

Pilot Report—Billy Vollendorf---180hp cub

I have owned the same Cub for 18yrs and have averaged 700+ hours a year in it. It used to be a stock wing 160hp Cub which I had flown over 12
years. and ran three engines to TBO. Loved that plane. It landed good and took off good, thought a Super Cub couldn't get any better. Ran my old
narrow deck 160 out and couldn't get any core charge for it, so I decided to try a 180hp.

I liked the horsepower but it took me awhile to feel comfortable getting into tight places. Getting out was never really an issue. It
didn't really matter how much you put in it, it would get off in 250 to 300 feet.

I hooked up with Mark many many years ago. We worked together fish spotting. Mark knew how good my old 160 Cub flew and was not very impressed with my new found horsepower. I didn't want to admit it to myself, but it was a different airplane. But Mark had a fix for my problem. He explained to me how my new engine mount was more nose down angle than my stock 160 mount was. If I was to change my thrustline to the stock thrustline it would solve my problems. So we did just that and I was never happier.. I had my old Cub back with a lot more horsepower. Flew my prototype Thrustline Mod for over a year and 1000+ hours and could find nothing bad about it. Takeoffs were better but the landings were where it was really noticeable for me. I was able to fly the plane slower with a lot more control. Just adding little bits of power would allow me to dangle the plane in the rough stuff without feeling like I was going to fall out of the sky. Before adding the Thrustline Mod little shots of power would simply
make the plane go faster and take away from your landing.

Meanwhile Mark was working on improving his mod even more. I would call Mark from time to time to see how he was doing with the certification. This process was much slower than I would have liked. He had made some prototype parts that would bring your motor angle up to 0 degrees. He
tested and got the mod approved on a friends 180 hp Cub and told me how well it worked. I finally got one of the first sets. I put the Thrustline Mod
on my Cub and was once again amazed with the results. I noticed as much increase in performance going from 4 degrees to 0 as I did from my initial
Thrustline to around 4 degrees which to me was a huge deal. Gained in cruise, 5 to 7 mph. It is hard for me to talk numbers on takeoff and
landing performance because conditions change so much. But I was able to my job with a lot less pucker factor, which is all that really matters.

I just rebuilt my fuselage with an entirely different frame. Before assembling it we measured my angle of incidence, among other things, to make
sure the Thrustline Mod would work. Mark has worked out some hard numbers that seem to jive with his modification. Mark knows his stuff and the
Thrustline Mod really works well. I believe in the Thrustline Mod and would not leave the ground without it.

Billy V.

Pilot Report---Mike Olsen—180hp exp cub(Mike Olsen Dodge—supporter of the Valdez Flyin)

Eric,everybody I know that have the thrust line mod Myself included find better performance,Take Off,landing,speed,stability ect.Plus if you don't like it use the money back warranty.Mike O.
Pilot Report—Jim Wheat---160hp cub on straight floats

Well Folks, I recently installed the Thrustline mod, and first of all I would like to say that Mark is really a pro; dedicated to his product and the customers satisfaction. He would not accept a dime until he knew I was completly satisfied with the mod. Where else can you find those ethics? Lets start with my cub, a 1957 160hp on floats with 5000 hrs. It was rebuilt several years ago with the usual mods and micro VG's. As for the thrustline, Mark supplied the measurments, and all was within his parameters. The installation was quite routine. The new spacers went on easily, with no need to modify any wiring, oil or fuel lines. The cowling rails went even smoother, and I believe my cowling fits better than before. Now, I'm just a float pilot, so I cannot speak for it's performance on wheels. Take off feels more powerful. It pulls up onto the step more quickly (especially with a load) and is at redline rpm from the beginning. Cruise speed is about 8 mph faster, and the really interesting thing is the wing has far less angle of attack (tail flying higher). It seems that to achieve the same cruise speed as before, it now requires about 150 rpm less. When climbing at the same airspeed as before (say 60) the climb angle is now much higher. The aircraft now feels much more solid at lower airpeeds (especially on approach) with a more noticable throttle authority. You just tweak the throttle to adjust decent rate. I'm still getting used to it, but I am a believer that its the best mod on the plane, and it makes it a safer plane.

Pilot Report—Jim Wheat---160hp cub on straight floats

I just returned from my first long trip with the mod. Two people, gas in the belly tank, and gear. We did a number of takeoffs from a 4600' lake. My cub is 160 hp on straight floats. I have done this trip a number of times without the mod so I was anxious to comare the performance. Boy, am I a satisfied customer. In cruise at 2450 it's 9 mph faster. The wing flies much flatter with a load than before. In takeoffs at the lake, it was on the step much faster than before. In landing config, its much more responsive to the throttle.

Pilot Report---Clint---180hp cub

I recently installed Marks (with Marks help) zero thrust Mod on my 180hp PennYan conversion cub. I first learned of this Mod about a year ago and finally decided to take the plunge!! I was not so sure after the first flight in gusty winds if I was going to keep the mod but after flying in better conditions the only down side I can find is loss of visibility while taxiing!!! The largest single improvement is in the landings.... feels more like a stock light cub, takeoffs are better and cruise is 4-5 mph faster.
Thanks for the help Mark!!!!

Pilot Report—Lanny Merritt—comments on Clint’s cub above

just thought I'd add a comment on Mark's new mod.I have a fair amount of time in supercubs,mostly off airport so I'm not a novice.I flew my partners 180 hp.cub before the zero mod and after.It is really a dramatic improvement.There is a gain in speed of four or five mph,but the impressive thing is how much slower the approach speed is.And not dragging it in nose high with power.It is a very comfortable attitude,and corrections are made with small power adjustments.One more thing,I have known Mark for more than a few years,you wont get a bs story from him,you will get good support.AKL21
Pilot Report—Tony Lee—160hp cub

Just wanted to comment on Marks Thrustline mod.
We installed the mod on my 160 cub a few days ago and prior to installation I did a base line flight to be able to tell the before and after difference.
I could go on and on about the improvements it made and they virtually mirror the previous comments. The most noticeable was the low speed handling and a 4-5mph top speed increase.
I have owned a cub for 30 years in alaska and been flyinging 300-400 hrs per year as a guide. It is a rare day when landings and takeoffs are not in rough areas with heavy loads.
The 2 most recent mods installed on my cub are Micro Vortex generators 5 years ago and the Thrustline mod last week. I do not know of many mods that you can hold in one hand that do more than these for the performance of a cub. The safety margin has definitely increased for for what a cub does best.
After installing the mod and flying the cub I walked up to Mark, who was on pins and needles, with my most disappointed look I could muster and he asked if we should take it off, I told him after the fist fight and started smiling. This mod works and his grantee of taking it off if it does not work should tell you a little bit about what sort of person Mark is. Congrats Mark on your great mod.

Pilot Report—Gunny---180hp cub/Slotted wing

Well we put Mark's mod in my SC last night and have only put about two hours on it since. The first noticable change is 110mph indicated on the airspeed indicator verus 100mph before in straight and level flight with light winds and 2500 rpm.

It also seem like there is less need for trim to compensate for the leading edge slots when landing light (i.e. no big load of gear in baggage) but we have to fly more to have the definitive statement on that.

We also noticed more elevator authority both in straight and level flight and also in t/o and landing. We need to fly that end of the envelope more and will have more to say after that.

Bottom line right now is an honest 10mph increase in airspeed and more responsive elevator. Mark's got a good thing going. We'll have more to say soon. Especially after we fly it back from ANC to Washington following the trade show. Looking forward to seeing everybody at the show.
_________________
Fly more, learn more - have more fun!
Gunny

Pilot Report—Mike Butterfield---(Builder) of Gunny’s 180hp cub/Slotted wing cub

Hello Mark! Thanks for your efforts getting this mod approved and installed on Gunnys plane. It has made a noticable difference in his indicated air speed and the A/C does seem to be lighter in pitch with more authority in the three point attitude. Sure enjoyed the demonstration that Billy put on with his Penn Yan Aero Cub, and I hope to be able to fly like he does when I grow up. Can see where they will benefit even more from this mod than the stock mount. Thanks for being such a wonderful host Mark, and good luck with your endeavor, if we at Air Classic can help, please allow us. Fly low. avoid the radar. Mike Butterfield

Pilot Report—Mark Drath—160hp non elec cub  Also a frequent contributor to Cub Clues Newsletter

Put the thrust line mod in today, did some testing, and thought I'd give some initial results.

Right before the change, we stretched a tape out on the runway, and measures max performance t/o and landings. Ran the plane into the hanger and did the mod as quick as 3 guys could do it. Took it right back out and measured max t/o and landings again. If anything, the head wind was definitely higher, and the temp cooler during the first test, so no environmental advantage could be given to the mod.

Take offs were definitely shorter with the mod, no question. Landings were also shorter right out of the box. After making a few landings, my spotters told me I was floating 10-15 feet past the touchdown line, and I made some adjustments, and started really cutting down the landing distance.

The air was to rough tonight to get any good cruise numbers or AOA, so will report those later.

Initial impressions on the kit-

The machine work on the parts is flat beautiful...Those shinny parts look completely out of place on a old work Cub. The installation instructions and paperwork is excellent and in order.

The tail seems lighter. In this Cub on a max performance take off, (stock), you would hold the brakes and add full power then use a lot of forward stick to lift the tail. Release the brakes and the tail would fall, so you had to ride the brakes for the first 10 feet or so to keep it up. With the mod installed, the tail starts to float up at about 75% power, lift it up high, release the brakes and it stays up. I have a feeling this has a lot to do with the shorter t/o distance.

Climb performance seems better.

Prop clearance is better, (sorry I didn't measure it Mark).

The cowl is higher, which does decrease forward visibility, but it's no big deal. I'll definitely take the performance trade off.

There is a better "feel" when slow. It's more comfortable right on the edge. When in straight and level cruise, the plane feels cleaner, like it is not fighting itself.

It is all good, just wanted to give some initial impressions. As you fly a mod, it gets hard to remember what it was like before, and comparisons get fuzzy, so want to get something in print now. If the amount of phone calls is any indication, Mark is really biting his nails on this, but I don't think he needs to, it works. I'm as sceptical as anyone when it comes to the latest miracle mod, but I honestly think this may rank up there with the Borer prop and Micro VG's when it is all said and done.

Been flying with heavy loads and aft CG's, and it really trims out nice in this configuration with a flaps down, slow, power on approach. Anyone who flies heavy loads into tight places is going to really like this mod.

Mark Drath

Pilot Report—Bob Breeden—160hp cub (edited for length) 

AkPA-1 asked me to be candid about the Thrustline Mod.

After a couple of months with the Mod, I can finally report a bit. First, it took some getting used to, to fly with change nose height which required relearning at a reflex level where the nose should be for the variety of angles of attack, attitudes and speeds flown. Having this become second nature was harder than the actual loss of visibility. The visibility loss was also quite something to get used to. Being tall is a great asset to this new sight profile on approaches. I literally mash my ballcap into the cross aileron cable with each glance over the nose. That is not as bad as it may seem, because at this angle you can see down where you are headed at max angle of attack that will still fly at very low or no power.

One thing that I have implemented to on and off airstrip landing sites is curving finals. There is a pretty art to an arcing, flaring, one wheel down landing at minimum airspeed. This can be done very slowly at a gentle bank to minimize airspeed, or a wingtip 8 inches off of the ground swinging landing. This is not necessary for seeing over the nose, but it does help.

The benefits are that thrust added or subtracted on landing is smooth, requiring no change in pitch to "catch" the plane and keep in on slope, which at super slow speeds with the stock "contrary" thrustline upsets things. That is gone. Hang her on the prop, make power adjustments for gusts, whatever, it is all real smooth. Yes, the plane can be landed slower because a little thrust on the backside goes a long way to a slower approach. Slightly faster landings in rough air are refined as well.

I got a good chance to work in gusts following the hurricanes. Hurricane Ivan passed through and spawned tornados that wiped out numerous homes in our county. The next morning was clear, but winds were 28 gust 40, and very rough as high pressure swept in to fill the low pressure void. Several landings and takeoffs were under 0 - 5 feet with locked brakes. These were conditions that the thrustline mod shined. Nothing like a Super Cub that you wear like clothes and fly as one with the machine. The mod helps this fine feel.
 
Takeoffs are great - it is like more thrust. If you are an engineer you can figure out how many pounds of downthrust are now gone now that no longer needs counteracting lift, but it is significant. 4 degrees is about 4 percent so 4 percent of 600 pounds is 24 pounds of now nonexistant downthrust. Is this figured out correctly? She sure peels off the ground and climbs out!

One other change in going to the Thrustline Mod is that walking around with the tail up with a touch of brakes takes a touch more power and brake for a given loading... and when you punch it to full power and immediately release the brakes the tail tends to fall through...until the bottom chord of the wing levels out with the ground at about 8 or 10 miles of airspeed in addition to propwash over the tail. The new efficiency at the rotating end of the takeoff roll; the new lightness felt there, far supplants this. With a little breeze the tail is up for the whole roll.

Well, I hope that gives a picture of the changes and benefits of the Thrustline Mod. I am glad to have it and plan to keep it. It is a feel thing.

Bob Breeden

Oh one more thought. I spend a lot of time flying with one notch of flaps at 55mph +/- 5. Loiter speed I call it. The plane feels very light and bouyant at these speeds with a notch of flaps. The plane drifts up to 60-65 at old power settings, or with slight nose down. So I have learned to fly with less power. Stomp on the power and you are up and away - very potent to launch away if desired. So the speed gain - the slipperyness and lightness I feel most at these intermediate speeds.

Pilot Report—Bob Breeden—160hp cub –Later report 

Mark,
Just a comment to say that the more I fly with the Thrustline Mod, I like it.
For anyone who might this could in any way be disingenious, let it be known that I paid full price for the mod - and have the cancelled check. I did benefit from Mark, Boz, Wilber and several other Cub Pilots at New Holstein who all helped with the install - so the installation part did not cost dollars. I genuinely appreciate what this mod has done for the performance of my Cub.

It is a pretty straight 1977 model, fortunately low time when I got it, so the fuselage has never been repaired, and the checks that Mark did on the wing root before the install with a digital level seemed to pass ok. Is that what you remember as well, Mark?

To get to the point, backside of the power curve work is incredibly fine mannered, and the plane can be landed much slower and shorter this way. Ramping up the power to check sink when transitioning to a speed below 40 is smooth and intuitive. No extra elevator pressure is required when adding power. She just flys easier, slower, and more stable. A normal, slow as possible power off glide-to-land type landing is just going to be longer....

Gusts are handled easier, something fearful when backside of the power curve previously. Of course, there are times when it is desireable to make a final approach speed at 50 or higher - real rough breaking air and wind shear. The thrustline shines here as well, because power added or removed when driving her in like that is lineal with the direction of flight, and does not require pitch changes to compensate for the power changes.

When explaining the Thrustline Mod to a friend with an Albatross who also has a Super Cub noted that the Albatross has its engines pitched way up to help it haul itself out of the water - and that also does help with the normal power approaches to water landings. Same in my case on land with the Cub.
Mark, thanks for your effort to get this Thrustline Mod approved. I've got to run into you again when I get back up north.

Bob Breeden

Pilot Report—Will F.—180hp widebody cub

Mark
Of all the mod's we put on our rebuilt wide body cub, this one is on top of the list.
The wide body is a great comfort mod for us plus size guys but as far as increased performance, the thrust line adjustment allows the cub to achieve the step much quicker than our other standard non adjusted TL cub. As far as the numbers go I can't say that the airplane is faster but it dose fly solid and slow on short final.

We fly from mid elevation lakes in the Sierra Nevada from 2000' - 9000' and the TL adjustment allows me to take gross loads into lakes that I can not fly the standard cub into.

Thanks for the great product and customer service.

Will

Pilot Report—Terry—160hp cub

 While I can't site numbers, given that my cub was in the hanger (annual, ski changeover and Thrust Line kit) for over 5 weeks and too many environmental changes happened between the "before and after", I can say, unequivocally, that I am very happy with the mod.

My cub went into the hanger on wheels with temperatures in the 40's, and no snow. We installed the Thrust Line kit and shoved it out 5 weeks later on skis, on snow, with temperatures in the 20's.

More than anything else, it gets the tail up where it belongs, affecting angle of attack on final approach, flare and touchdown, as well as lift off and climb out. Even without numbers, I am sure I've got shorter takeoffs and landings. I can't validate my cruise or climb performance because too many things have changed, but my cub has never cruised as fast as it does now.

My off-airfield takeoffs and landings are better than ever and I attribute most of this to the improved approach attitude and quicker lift off since the Thrust Line kit.

Pilot Report—Larry Goodman—180hp cub and a man of many words!

I got my thrustline on. It's faster , It's slower , It has my kind of people behind it . Larry