Takeoff distance issues

[8451]

Have you confirmed your tach is accurate?

The tach was checked about a year ago with an optical sensor that was hooked up when I was checking if the prop needed balanced. It read within 10 RPM of the tach.

[2066]

Mike wrote: "...One of Mac Forbes outstanding A&P IA’s..."

The same one who observed when tearing down my own "leaky" C-85 @ 2700 past TBO: "Mac, we've torn down a perfectly good engine!" . Of course, he went on to accomplish an expert major around the 0-200 crank STC, making it better than ever...and, without the previous pesky oil leaks! . Mac

[8376]

The simplest fix...

Move to Alaska, current density altitude is 100 in Anchorage. Fly in the winter and expect somewhere between -4000 and -6000 up north.

Jimmy

[8322]

I'd definitely check your weight... I would say even heavy in "normal" temps lets say 50-75 I'm in the air under 1000... I too have no idea exactly what airspeed I use... I think its around 40mph or so, as she's usually doing 45 or so when I look down once solidly in ground effect, I keep her close to terra firma till I'm at 70 and climb out 400-600fpm with a c85 stroker....

My gal was heavy when I got her at 1012 on a re-weigh, I'm anxious after a couple more projects to do another re-weigh but I'm hoping for under 950, especially if EarthX gets their STCs done soon so I can have a 4lb battery. I went into my weight loss project with the mentality "ounces make pounds" and have kept all the crap I've taken off of her, old loran wiring, to the interior upholstery (I painted my interior) and the horsehair seat back was good for about 6lb reduction in weight alone... They can be thinned down!

[8451]

Weight it definitely on the to-do list.

Tire pressure did appear to help some. I flew yesterday with the mains at 24 PSI and at 1300 lbs estimated TOW was able to take off in less than 1K' on pavement. I can tell just moving the plane on the ground rolling resistance is a lot less.

[a64pilot]

Daniel, re-addressing your original concerns about takeoff performance, I would echo what has been said here about not depending on the airspeed indicator to tell you when your airplane is ready to fly. On grass, shortly after beginning the takeoff roll, relieving tailwheel surface drag by slightly lifting it, then tickling it into the air when its body language tells me it is ready to fly works for me on a normal takeoff.

That being said, I respectfully disagree with the notion that these airplanes are "dogs".

In the "tire pressure for 800-6 tires" thread, Jody you make the statement, "In my opinion a 140 isn’t a good bush plane". Compared to what? A $70,000 Super Cub? A $150,000 Husky? If those are your benchmark, you may have a point. But for our $30,000 or less airplanes producing less than 100 HP on takeoff, my experience in my C-90 powered 120 with cruise prop is that it makes a great little bush airplane and I'll gladly do a flyoff against a standard Super Cub. No it won't outdo a miracle Cub or Husky on steroids. But does this disqualify it from being a good bush airplane? Not my 120, flapless as she is.

Lastly, Leadville, elevation 9934 ft. A stop and go there says lots. Hopefully though we're not establishing Leadville as a new
benchmark against which our airplanes are now going to be judged.

Primary purpose of a “bush plane” is to haul “stuff” your not hauling much stuff in a 140.
secondary purpose of a bush plane is short field work, and a 140 cruises fast for 85 HP and due to wing angle of incidence etc it gives up quite a bit of short field performance to get there.
Then many times to get into bush strips you have to come in over high obstacles, usually trees and for that, you want an airplane that glides like a brick so a very steep approach is possible, a 140 is pretty clean aerodynamically and as such it glides pretty good, which makes steep approaches difficult.

A 140 cruises from my little bit of experience at 105 MPH and can carry two people and fuel. That’s a respectable speed and useful load for a 85 HP airplane.

In my opinion trying to make a 140 into a bush plane just really isn’t playing into its strengths, it simply wasn’t designed for that purpose, it would be similar trying to make a Mazda Miata into an off road vehicle.

Besides off airport use is tough on airplanes, and every day there are fewer 140’s in the world.

[6863]

Yes Jody I agree that trying to make a bush plane out of a 140 is not playing to its strengths, particularly if you are relying on a C-85 and the 140's straight hinged flaps. Having flown the sub-Sahara African bush and jungle professionally for nearly a decade, not in a Cessna 140 of course, and with engineering test flight experience of my own I hardly need a lecture on the primary purpose of a "bush airplane". But what I am saying is that looking at benefit vs cost and using good technique, I've been impressed with what my airplane can do. I believe for the most part that our airplanes' capabilities exceed the capabilities of their owners. Feel free to compare your airplane and how you fly it to a Mazda Miata, but don't include me and mine in that comparison.

[5422]

So every bush strip is short with giant obstacles on the end.....Guess all those years flying off beaches, gravel bars, mud flats and ridge tops in Southwest Alaska don’t count. One thing is for certain you gotta pick your strip really carefully cause that tail section is pretty weak at the bracket and the spring attach points. I beat the hell out of our 140 when I was in my teens and now that I have completely restored it (it wasn’t cause it was wrecked either) I baby it and it stays off any rough stuff. At gross with an O-200 and 69/50 prop I can do a stop and go within 1000-1200 feet. That’s pretty good for having stubby metal wings and being a heavy 140 overall. I might haul it in the air at 400-500 feet but I won’t be clearing any 50’ obstacle soon after. That’s with 8.50x6.00 tires on pavement, if those heavy 29” bushwheels at 5 psi are installed It easily ads about 70-100ft. add some soft sand, mud, knee high grass or standing water and ours needs a good 1500+ feet to get airborne.

I think any plane is only as good as it’s operators experience level. There is a fair amount of 120/140 planes up here that are used off airport for people that can’t afford a Husky or Cub. It still allows those folks access to some good fishing and hunting areas safely at a reasonable cost. Yes, it wasn’t specifically designed as a “Bush” plane. As long as your careful it can take you to those “Bush” places. That said It doesn’t even come close to the safety margin our Cub provides as far as short field/obstacle issues are concerned.

CDB10C64-0CF6-40C8-95D7-7853AEDBCC18.jpeg (370.88 KiB) Viewed 5238 times

[a64pilot]

My last airplane was a Maule M6/235.
specs I found on the internet was 150’ T/O and 450’ over a 50’ obstacle, But light you can easily beat that. I would normally take off and land before the end of the numbers on the runway, however long they are. ( with the normal average 5 to 10 kt head wind, that really helps.)
https://www.aopa.org/go-fly/aircraft-an ... ts/maule-6
For those that want to decry it as a rich mans airplane, I paid 50K for mine I guess about 15 years ago, Maule’s are cheap airplanes, Cessna’s on the other hand are not.

Our little Cessna’s can be operated off airport of course, but as was noted it’s really hard on an old Gal, and they just don’t have the performance to really do much other than for you to say you landed on that large, long bar.

This is a print from a real photo, back in the day, I’d guess the 70’s. It’s a little misleading as it’s really the Maule factory in Moultrie Ga. that does look like a hangar, but it will give you maybe 100’ roll
https://www.aviationarthangar.com/avarthabebai.html

I’m not trying to sell Maule’s, but if you want a bush plane, don’t beat your 140 up, they are old and every year there are fewer and fewer of them, but then I’m the guy who hates to see Warbirds modified and raced too.

[8451]

I wanted to provide an update on this. I increased the tire pressure on the mains to 24 psi and I've been practicing technique. I think alot of my previous issues were indeed technique based, as I've found that I get off a lot sooner by going tail up and positive rotation rather than tail low and wait.

At approximately 1250# TOW I've been able to take off in approximately 700' on pavement.