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Super Cub to 23000 feet - Engine/mod combo?

fisher.garrett

Registered User
Hello,

I would like to find a Super Cub that can make it to 23,000 feet to fly around some rather large peaks in the Andes. I am not a novice to high altitude flying, as I have flown a PA-11 to the 58 peaks over 14k in Colorado, every glacier in MT, WY, and CO, the 82 highest peaks in the Alps, 129 highest peaks in the Pyrenees, etc... As one can tell, this is something of an addiction.

I am aware that the PA-18-150's service ceiling is 19000'. I am also aware that my PA-11's service ceiling is 16,000', and I have exceeded it while carrying a rather heavy load. Anyhow, I am curious if anyone has experience on how high a 160hp or 180hp can go, or what difference a climb prop makes in any engine combo. I have heard anecdotal evidence that vortex generators can help service ceilings, though I am not certain of it, as the event in question with the PA-11 was without vortex generators, and then I struggled to get above 16000' again with them installed later on, though it was also a winter vs summer service ceiling test. There are also ISA altimeter differentials when its 10F surface temp vs 86F and I equally make it to 16000'.

I have access to a spunky PA-18-135 that will be getting VGs installed, so I can do a ceiling test before and after. I also have access to a PA-18-150 I can rent in France, located at an airport where Class E goes to 19,500', just to see how the book compares to reality.

It is also conceivable that I would have to ride mountain waves to get up that high. I routinely do it in the PA-11, as sometimes its the only thing that will lift my sorry 267lb rear end.

Somebody will probably recommend something other than a Super Cub and, well, I grew up on them and part of the challenge is to push a Cub and Super Cub as far as they will go. Something about a 300hp Cessna is entirely unattractive.

Thanks for any suggestions.
 
What kind of oxygen setup do you use?

Very basic for occasional forays above 14k. Would need something more robust to get to 23k, though that is secondary to getting there first.

Turbocharger to me seems rather complex and prone to complication and breakdown. VGs and prop is easy. Engine....well, that is a decision to be made before buying the Super Cub.
 
Just saw the 30,203' Super Cub record article on the site. The same lady I believe (or someone similar in FL in the early 50s) got to 25,000' in a PA-11. She must not weigh too much.

This confirms what I suspected: that it can be done without going crazy on the mods. There are also some extremely high airfields in the Andes, so that would make a good starting point and cutoff the total climb. I do know when I based the PA-11 at Leadville (10,000'), it made it much easier getting to 16k than taking off from 1582' in Switzerland and climbing a full hour to 16,000', burning about 40% of my fuel before I even got there.

My philosophy has always been that downward air is a non-starter, so just find the stuff going up and ride it. It works most of the time except mid-summer as thermals tend to move around and don't stay put like waves.
 
George Kitchen once showed me a Polaroid photo of the view from the pilot seat of his Super Cub. Clearly in view over the cowling was a mountain peak. I looked at the picture, and said “okay.....”. George said “Lookat the altimeter”.

It read 22,000. Mt. McKinley south summit.

I asked how he got there, and his response was “favorable winds”. He did say the ride back down was less fun.

George used to fly cover for Don Sheldon when Sheldon was doing something risky.

MTV
 
Sailplane record is now 76,000' https://www.youtube.com/watch?v=KE792Y9hyww If you want to use wave 23K is easy. Be aware of time of useful consciousness if your O2 malfunctions. Might want to look into some of the other aeromedical factors if you want to play high. Have fun.
 
I have probably 1000 hours of missions over the Andes. You can get up there in a 180hp and even a 160 on a cool day, but your performance margin is nil. You will certainly encounter down drafts that will exceed that margin on the lee side as well as a high likelyhood of IFR conditions because you are in the ITCZ. Nor will you encounter these conditions at the peaks but many child peaks as well. The Alps and the Rockies are a piece of cake compared to the Andes. Let me put it this way, on more than one occassion I have been above FL350 at MCT, airspeed at min clean (L/D max), looking for a block altitude assignment so I can "give her its own head". The only other place on earth that happens with some frequency is Iran.

If you are stuck on doing this I would get a good miision control with a metro guy with excellent local knowledge as well as turbo prop recon ship with gps nav to get good winds. Anything else is beyond high risk. It is a heck of an adventure and it can be done, how it is done determines the risk.

As for O2 a portable with a continuous flow mask is good to FL250. Beyond that go to a pressure mask.
 
From a 2003 string on this forum:
Bob VanTreese

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My 2 cents worth--

My personal record is something like 15 or 16,000 feet while towing gliders out of the old Black Forest Glider Port and the Air Force Academy in Colorado Springs. That was with a 180hp Cub.

In 1985 or 86, there was a guy flying a PA-18A/180 out of Meadowlake Airport east of Colorado Springs who was trying to set a record. I was there on the ground one day when he made it up to 28,000, and I think he later got it up higher. Can't remember his name, but I do remember he was a retired AF Col.

I also had a friend who bought the Super Cub 150 that I had a partnership in and got into the crop dusting business with. He took it up to 20,000 one morning. ("I don't need no stinking oxygen").

There was a Canadian, eh, guy back around 79 or 80 who took an Interstate Cadet up to 31,000 or so in the mountain wave off Pikes Peak and set a record which I think still stands.

I did about 5 years, 4,000+ hours and probably 20,000 glider tows in a 180 Cub back in the early to mid-80's before I got into the airline business, and I do miss the flying. Somehow, the 767 just isn't the same...................

Bob VanTrees
e

Garret, I love your images, and salute you for this project. You seem to have the wave thing fairly well figured out. I'm sure the European, and especially Alps soaring community has some good meteorology resources available: Lots of good weather and climate modeling coming out of there. I'm pretty sure that Bob Van Treese was towing for Dave Johnson, and that more than one of those tuggies might have "inadvertently" blundered into wave above 18,000', when that was still legal. But heck, if an Interstate Cadet can do it, why not a PA-11? Please let us know how this project progresses.

Thanks. cubscout
 
You might want to check in with Aeroclub Bahía Blanca a couple of members took a Cessna 140 along the Andes all the way to Oshkosh.


Sent from my iPhone using SuperCub.Org
 
Thanks everyone!
- Will definitely contact the mentioned Aeroclub.
- The stories about stock PA-18s heading above 20,000' are excellent info - I suspected as much and its good to confirm.
- Bolivia mission Cub: would love to hear how that works out.
- Waves and Mountain Wave Project: Klaus Ohlmann, one of the guys breaking a lot of records in the gliders in the Andes, stopped into La Cerdanya here in the Spanish Pyrenees with his Stemme a year ago. I was monkeying at the hangar toward sunset. It was cold in the dead of winter, windy, and nasty out with presumably massive waves, and he taxied up as it was getting dark, intending apparently to walk 2 miles to his hotel. Needless to say, I drove him. He took the Stemme to the Himalayas previously and told me about it (after the Andes for me. Ha!) Anyhow, we get massive waves here in the Pyrenees and unfortunately the home base is on the wrong side of the typical north wind waves which go to 40,000'. Some of the yahoos here do some crazy stuff - the stories I hear are rather nutty. Nonetheless, I have gotten better at poking through the clouds at just the right spot near terrain and sliding into the 50kt laminar flow and riding it for awhile (in the PA-11). I haven't gone for 19,500' yet (max Class E here), though one of these days I'll give it a try.
- GeeBee: I'd like to hear more about where you were in the Andes. I intend to hit the 102 peaks over 6000m/19685'. They start near Santiago Chile and most of them are in desert-ish regions, with the exception of a handful in northern Peru and one in Ecuador. I have been to the peak in question in Ecuador up to 17,500' on foot. Bit of a workout. Locals tell me the infernal nonstop rains quit and its quite sunny in August, so my intention would be to head north from Peru in the "Valley of the Volcanoes," conduct my business, and get out to the Humboldt-influenced deserts, which transition oddly quickly. I don't do jungles. My curiosity is where the wind blows in those regions. Its westerly in Santiago, easterly in Atamaca and the Altiplano, and then TBD in the equatorial region. Stay on the proper side of the ridge and its all good. With the PA-11, I can't out climb a downdraft at 9,000'. I just run with my tail between my legs in a worst case scenario and it so far hasn't killed me yet.

The plan is to do this in 2 to 3 years bit by bit, starting out of Chile. As for O2, I'll work up something, though I do plan on testing with an sp02 indicator with an oxygenated pilot as PIC, just to see what the pulse ox readings are at 20,000' in the event of O2 system failure.
 
Went up to 18k last summer over the Sierras in a 160 hp PA 18.
Dead calm day, no wind no wave. Still climbing 200’/min when I chickend out and returned back to earth.
In my case I was about 5000 above the highest peaks, not sure I’d feel comfortable flying amongst higher terrain with such marginal performance.



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Lycon 160 hp
Catto 82-39
E/W 1100#
half fuel (18 gal)
20 deg oat
 

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Gary King senior (of Anchorage Sporting Goods stores)showed me a photo of his panel in his old NON turboed 206, right in front of the spinner is the
Summit of McKinley, seconds before he crossed it at almost a right angle, "maybe" a 100ft above it!!!! Everyone that ever saw it
either said " are you crazy" or shook their head and walked
away............. Impressive photo though.
We used to fly by it on perfect days in the King Air but parallel to it, and it can make you feel like a mosquito!
 
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Gary King senior (of Anchorage Sporting Goods stores)showed me a photo of his panel in his old NON turboed 206, right in front of the spinner is the
Summit of McKinley, seconds before he crossed it at almost a right angle, "maybe" a 100ft above it!!!! Everyone that ever saw it
either said " are you crazy" or shook their head and walked
away............. Impressive photo though.
We used to fly by it on perfect days in the King Air but parallel to it, and it can make you feel like a mosquito!

Well - if he was with the wind, it is less risky than the other way around.


I decided to test my theory and got the PA-11 to 19,500' today. French ATC put an end to the party despite my repeated requests to go higher. Apparently when the wind (and waves) shift, Spanish ATC takes over prime wave regions and they are more accommodating. Upper level winds were 58kt and smooth. (Image: Spain left, Andorra foreground center, France right).
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The Col. mentioned in the previous post by Cub Scout is my brother Richard L. (Larry) Griffin, flying our 1959 PA18A, O360, 1937G. We still own the airplane, based at ERV.
 
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Took the Andes Cub up to 19K yesterday. I was at about 1525 lbs.gross.

Sent from my SAMSUNG-SM-G900A using SuperCub.Org mobile app
 

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Fisher, how about some other ideas that could help.. Up in the rare air, you will be aided by square tips and extended wing tips if you can pull it off. More aspect ratio will help. But excess hp helps you climb. Light as possible. The most wing and maybe a mid prop?.... Vx and Vy come together at max alt. I wonder if a pure cruise prop and a pure climb prop would do well in the middle, slightly leaning more climb? Lastly, I’ve heard that two similar cubs, one round tip and one square will climb together until around 8ish k and square will start to climb away. Good luck.
 
Not quite that high - because I didn’t have O2, but I’ve been in a Cessna 150, o-200 w climb prop, crossing mountains in the Co Rockies at just under 14,000 pushing forward to prevent from having ridge lift push me higher. Sailplaning in a Cessna.

Crossed the ridges at 45 then spent the next 20 minutes on the other side of the ridge trying to keep the greasy side down and out of the trees, in moderate to sever turbulence. Don’t know how I survived my 20’s?
 
With a pax and 30 gals fuel.
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Not too high, about 12 K max, but I've had several hour dead stick ridge soaring flights on the range behind my place, in the Rans S7. Shut it down at 8 K, stayed up until it got boring. No big deal, soared the same ridge decades ago as a hang glider pilot, like riding a bicycle. Heater doesn't work well though.
 
Since the real challenge is going to be high, wouldn’t a long prop, pitched coarse be desirable?

MTV
 
Since the real challenge is going to be high, wouldn’t a long prop, pitched coarse be desirable?

MTV

i would think it’s all relative:

thin in air provides less “bite” for prop.
At the same time engine is making considerably less power.
coarser prop would lug the engine, high cyl temps would result.
I think...
 
The Catto 86/38 on the Cub I fly seems to do well up high. It statics 2300-2330 rpm at 8,500 ft or 12,500 ft. Doesnt seem to matter. At sea level I think it statics 25-50 rpm more. Cruises 90-92 mph TAS at 2500-2550 up high burning 6-6.5 gph. Down low it will do the same mph with slightly less rpm (2450-2500) but burning 8-9 gph.
I do notice that above 15,000 ft in level flight I can go full throttle without overspeeding. Down low it will overspeed very easily at more than 2/3rd throttle.

Sent from my SAMSUNG-SM-G900A using SuperCub.Org mobile app
 
I do notice that above 15,000 ft in level flight I can go full throttle without overspeeding. Down low it will overspeed very easily at more than 2/3rd throttle.
I agree with MTV, you are leaving a lot of horsepower on the table. You should be able to go to full throttle or nearly so down low without exceeding 2700 rpm. At altitude your maximum manifold pressure will be reduced. So at 15,000 you would be lucky to get 60% power at full throttle 17" mp and 2700 rpm. Take a look at Lycoming's power chart.
 
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