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First Super Cub

D

Dterhaar

Registered User
Lake Ann Michigan
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Hello, I am a new member here and this is my first post. I just purchased this 1961 PA-18-150 that had 3 hours on it since a total restoration. This is my first tail wheel plane. I put my first couple hours on it yesterday while getting my tail wheel endorsement and it fly's great and nicely trims to hands off level flight. My issue is it seems to require an excessive amount of back pressure to hold the stick in the full aft position. Is there a standard specification for the amount of force that I can measure at the end of the stick? Are there any adjustments that can correct this? Is something with the trim out of adjustment causing this? What is the specified total amount of travel in degrees up and down for the elevator to the hard stops?
I may have to start a new workout program to be able to taxi this thing on floats!

Thanks for any feedback!
 

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View attachment 1A2.pdf

The TCDS for the PA-18 is attached. Since your spring is new on the elevator it may take a bit of exercising.

If you are trimmed all of the way nose down it will also make the spring tighter.

Tim
 

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Welcome Dterhaar, Your airplane looks very nice. Is the stabilizer in the full nose up position in the picture? If so the leading edge should be resting on the top of the top longerons. Also there is a spring/cable assembly which is attached to the trim yoke, up over a pulley and back to the upper control horn on the elevator. This is supposed to pull the elevator up when the trim is moved to the full nose up position. In your picture this does not appear to be happening. Some of the early Cubs had this same arrangement on the bottom as well. There is a bulletin to remove the bottom spring/cable assembly. This will reduce your back stick force.
Others here can give you more specific details on this.
 
Ditto Skywagon8a. When I first started flying a early J5A-75(same TC as PA-12)) it lacked sufficient "Up" trim and wasn't fun to fly. If you let go of back pressure in glide it would go over 100 mph. This forum was a great help. It didn't have the bungee system. It also had a slipping trim. We got a up bungee kit from Univare and it became a different airplane although not perfect. The example I flew had damage history, was put together from two airframes so could have been bent? Don't know exactly what you have going on? But w/o the bungee system I bet it could be a handfull. I can't imagine it being assembled w/o the system?
 
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Thanks for the feedback. I did check and I do have both the upper and lower bungee spring assemblies. I think I will remove the lower bungee and give it a try. I wonder how many PA-18's are running without the lower bungee since it is not required? Also I notice that the top elevator cable seem to go slack when the stick is pushed forward to the stops??
 
Dterhaar said:
Also I notice that the top elevator cable seem to go slack when the stick is pushed forward to the stops??
Click to expand...
This is an indication of insufficient cable tension. When the stick is pulled back, does the elevator hit it's up stops firmly? If the tension is low, there is a possibility that you are not getting full up elevator to the stop during landing.
 
Does this Super Cub have the Cub Crafters 2300 lb Gross Weight STC? If it does the bottom spring is required. If STC is not removed I would remove the bottom spring for sure.

Your Super Cub looks great. A little close to that hanger door without the wheels being chalked. Fixed a couple of nice airplanes that got bent from not being chalked and blowing into stuff. Just a heads up. Congrats on your new Cub, many adventures await.
 
skywagon8a said:
This is an indication of insufficient cable tension. When the stick is pulled back, does the elevator hit it's up stops firmly? If the tension is low, there is a possibility that you are not getting full up elevator to the stop during landing.
Click to expand...
It is normal for the upper bungee cable to go slack with full up elevator.
 
Its has the 2000 lb Wip. STC so the bottom bungee spring is going away. After 20+ landings in a row the excessive aft stick pressure was getting very distracting while trying to learn the feel of the plane.

Wonder why the CC 2300 lb. STC requires it?

Yes, my top bungee spring does go limp at full up elevator but the top elevator cable going to the rear stick also does when I push the stick full forward. I can push the rear stick full forward and reach down and grab the cable and wiggle it enough to hear it rattling the the fuselage. What should the elevator cable tension be set to? 30 lbs.?
 
I will work on these adjustments this weekend.
How about any suggestions on engine performance upgrades. It currently has the 150 hp narrow block in it with only 150 hours. I would love to do the 160 hp but seems like a waste with the low hours. What about exhaust, electronic ignition or prop? All currently stock. (I do have some new 26" Good years for it but thought id wait until my on the pavement training is done to install them!)

Thanks again!
 
You won't wear those Goodyear's out. Electronic ignition will get you a smooth idle and a better fuel economy at altitude. You can gain 50 rpm and loose some weight with a Sutton exhaust or gain maybe 100 rpm with a Hot Rod muffler. All you can do is bootleg a 160 go with pistons but need longer studs for the banana plates to be legal. 160 makes a difference but is expensive on a narrow deck to convert legally. I say fly, fly fly and through out the weight you don't need. VGs?
 
Since it does have float fittings I was just kicking around putting it on a set EDO 2000's to fly it to the cabin in Upper Michigan. I wasn't sure on how well it would perform on floats at near gross with the stock 150 hp. That way i could leave the Cessna on wheels for the summer and thought I may be able to get into smaller lakes once up there and unloaded.

Yes it does have VG's

Good to hear about the Goodyear's, I will get them on ASAP so I can get a feel for them with the CFI.

Dave
 
Nice looking bird Dterharr,
I just purchased a PA12 with a 160hp, and am putting on VG’s, 850 tires, and a new prop.
I’m flying out of Lapeer, MI but should be in the air soon. Have fun and look forward to seeing you around the patch. Cheers


Sent from my iPad using SuperCub.Org
 
Dterhaar said:
Since it does have float fittings I was just kicking around putting it on a set EDO 2000's to fly it to the cabin in Upper Michigan. I wasn't sure on how well it would perform on floats at near gross with the stock 150 hp. That way i could leave the Cessna on wheels for the summer and thought I may be able to get into smaller lakes once up there and unloaded.

Dave
Click to expand...
A stock 150 hp Cub does a great job on EDO 2000s. It does a great job when lightly loaded in very small ponds. What do you call a small pond? Smaller than 900 feet long with low trees on the ends? A light 150 PA-18 on EDO 2000s will do nicely in a 900 foot sea level pond.
All of the "extras" which are discussed here, while they do do something, are just a little frosting on the cake.
The Super Cub isn't called "Super" for nothing.
 
If you already have Bendix mags I would stick with them unless you do a lot of high altitude flying. The key will be the prop get a long one and pitch it for the performance you need getting off the lake. Exhaust will help a little, I do a lot of winter flying so I prefer a Hot Rod only downside is it makes more noise.
DENNY
 
Wow, they do well on EDO 2000's! With my Cessna on EDO 2960's fully loaded (1300 lbs. use full) at sea level I like to see a 2800' lake for a minimal pucker factor.

Dave
 
IMG_0660.jpgCan you tell from this picture if I have a factory exhaust system?


Dave
 

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I removed the lower bungee spring and cable today and it made a huge difference on the aft stick pressure, mush nicer to fly! Checked the tension on the elevator cables and they were at 52 lb. which is a little low. If i push the stick slightly against the forward stops the top elevator cable tension drops to 20 lbs. or less? The aileron cables were at 58 lb which is high, it feels great in the air but not sure if the high aileron cable tension is bad for the pullies ?


Dave
 
I saved 2 lbs between my stock Super Cub exhaust system and the Sutton system. Got the muffler off the firewall, less heat in summer. Easier to work on and no exhaust AD.
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One of the first things I would do is fix that big gap on the back side of the baffling. Don't let anyone talk you into moving the oil cooler to the back it makes working on things a major pain. Also consider a 4 cylinder CHT/EGT.
DENNY
 
DENNY said:
One of the first things I would do is fix that big gap on the back side of the baffling. Don't let anyone talk you into moving the oil cooler to the back it makes working on things a major pain. Also consider a 4 cylinder CHT/EGT.
DENNY
Click to expand...
I saw that as well but when I blew the photo up it appears there is a seperate piece of baffle matterial there.
 
PA-18 performance mods
1 Borer prop although expensive will get you 25% shorter takeoffs on wheels and maybe more on floats. 5500.00
2. Thrustline mod is inexpensive and does amazing things on -18 with correct AOI and nothing on airplanes with Low AOI. 1800.00 or so
3 loose all the heavy old accessories, Aluminum oil cooler, light weight B&C starter and Alternator and the lightweight Hawker battery will shed a lot of lbs and you much more reliable equipment. 2500-3000
4 Atlee Dodge hot rod muffler make a significant power difference and you will still have good cabin/carb heat. 1800.00
if your engine was a wide deck 160 hp pistons would be second but on your low hour Narrow deck you have to change the case through bolts and unless your willing to 5000 or so for those 10 ponies skip it for now and learn your airplane by converting gas to noise. 160 hp engines will burn 1 to 1.5 gph less fuel than 150 hp engines and it seems like a lot bigger change than 10 hp so you might keep your eye open for a deal on a WD build it the way you want it and sell your narrow deck.
I also think Cub Crafters rudder and elevator gap seals at 250.00 or so are a complete no brainer. They give both a lot more authority.
dave
 
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Also, AOI is everything on a Supercub, it’s what makes some a rocket and others a PA-12 performance wise. Have someone measure your bird that knows how or Call Mark at Thrustline, he will talk you through it, it’s nice to know even if you don’t fix it and there are A lot of cubs flying around with uneven AOI and they will try hard to kill you if you ever get them to depart scared S2D and I half to death 36 years ago this month.
dave
 
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