Take off and landing distances

[Daywalker]

Greetings everyone,

Perspective builder here. I was wondering if anyone has ever tried to compile any take off/landing distance performance data for the 4-place? I’ve seen lots of claims and videos regarding the shorter distances and am so far impressed. But I’m looking for worst case scenarios ie. A higher altitude strip, hot and fully loaded. Off an unimproved or grass strip as well.

Obviously, I know a lot of build features, equipment decisions as well as technique will vary the results. I’m considering a 540, or equivocally powered engine if that helps, as well as adding stol features in the build.

Cheers,

[Mark Goldberg]

The stock 4 place BH is a very capable STOL plane. The biggest factor is your ability as a pilot. Some of us are never going to win any STOL competitions like Jonathan does in New Zealand with only VG's and Hoerner wingtips as modifications to his plane. Pilot skill. Mark

[Daywalker]

Sure Mark, totally agree that technique will vary the distances produced. I think I've seen most of the Bearhawk STOL videos out there and am impressed, but the reason I'm asking is because I've got specific strips/missions in mind. The website states 2-500' take off roll, nothing on landing distances. I went for a ride in one a few weeks ago and thoroughly enjoyed it, but it was still below zero, just the two of us onboard and from pavement.

I'm just wondering if anyone out there has some distance numbers (even ballpark) for when the aircraft is at gross, in warmer temperatures and at a higher field elevation. Thanks.

[WyoDave]

Could you tell us the strip length and elevation you have in mind?

[zkelley2]

I've yet to see anyone do any real performance calculations based on test data even to the horrific standard of piper spaghetti charts, despite that being a highly recommended thing in phase 1. I think everyone goes with the TLAR method. Kind of like how you have to go flight test to include stalling your airplane at the aft-cg limit, or adjust the aft cg-limit to where you tested it to. No one actually does it.

[Daywalker]

Mountainous.. say 1,000' grass/dirt (some are shorter), highest field elevation about 5,000' with a temperature of 30 deg C. roughly in the 8,000' density altitude range? Fully loaded I'm wondering if the airplane is going to have issues in this regime, or would it be fine? Has anyone got some rough numbers on how their plane performs in those conditions? I'm also considering on putting the airplane out of a farm strip eventually, and wondering on how much/little length I can get by with. Cheers.

[Gerhard Rieger]

HI, in South Africa we have many airstrips that are 5000ft and up with 30deg C temps and more, the main thing to remember when you are used to flying at lower altitude is to lean the mixture correctly for altitude. I fly a C172 from 4250 ft asl 4 paxs on a 30 deg C day not exceeding gross weight with fuel from a 6000ft strip that leaves a lot of room for error, but on my strip on the farm that is 1800 ft with the same alt, I will not even think about it. My Bearhawk will have the IO540 and I will be much more at ease with 260 hp and a stall wing design on a short strip.

[Bcone1381]

You want Real Data. I'm 90% confidence in the following recollection from my memory.

Phil Johnson lives in Missouri and scratch build a O-540 four place with no VG, or Hoerner wingtips. He is an old missionary pilot. (Thats a data point regarding Phil's skill set and experience) He has an 800' farm strip. At Oshkosh last summer he said that he flew in and out of it at gross weight in the summer. Someone here on the forum has his contact info I bet. My guess is that means his Density Altitude might have been 4000.'

[zkelley2]

You want Real Data. I'm 90% confidence in the following recollection from my memory.

Phil Johnson lives in Missouri and scratch build a O-540 four place with no VG, or Hoerner wingtips. He is an old missionary pilot. (Thats a data point regarding Phil's skill set and experience) He has an 800' farm strip. At Oshkosh last summer he said that he flew in and out of it at gross weight in the summer. Someone here on the forum has his contact info I bet. My guess is that means his Density Altitude might have been 4000.'

That's still an anecdote at best. Which seems to be all anyone has for data. I've yet to hear of anyone going out and doing any kind of real testing with the airplane.

[jaredyates]

I have an airplane, a pilot, and a mesuring wheel to contribute. What other vacancies are on the signup sheet?

[zkelley2]

I was hoping to do this later this year also if I can get much time off work.

[Mark Goldberg]

As I said earlier in this thread - pilot skill makes a huge difference in the numbers people see in their Bearhawks. I will contribute some data points even if they are not exactly the situation you describe.

When I lived on a paved strip with probably 2,000 ft density altitude common - I would see take off (no wind) at full gross of 450 ft. Me being an amateur pilot with skills anyone can duplicate. When light, 250 - 300 ft take offs are easy without pushing anything. My same BH in the hands of a better pilot and light - saw consistent 165 - 185 ft take offs in the STOL competitions. That was with my two blade metal prop. With the Trailblazer carbon fiber prop - the distances went down by 30% or so.

One more anecdotal story. One the way out to the EAA event at Arlington WA, my BH stopped for gas in Leadville CO. Density altitude was around 10,000. The airport manager told the pilot that he had only ever seen one plane take off shorter - a PA18. And that was back when it had the metal prop. And full tanks. Mark

[svyolo]

I have never flown there but I have driven through Leadville several times. I highly recommend the Independence Pass for a road/camping trip. Leadville is a cool little town.

[Daywalker]

Yeah sorry guys, it's just the career pilot in me that's got me searching for some hard numbers. Still trying to learn as much as I can about the homebuilt world. As much as I appreciate the anecdotal accounts and the TLAR method, it would make me feel a lot better if I could at least have some consistent numbers or experiences from pilots operating in those ranges, or similar to what I have planned, before making such a substantial investment in time and money.

[svyolo]

Wing loading and power to weight ratio are two good numbers too start with.
The EAB world also doesn't have 2000 hours of test flights, with 100% standardized equipment, and performance correlated for atmospheric conditions, published in performance documentation that used to be several inches thick, back in the old days when they published things on paper.

[jaredyates]

Yeah sorry guys, it's just the career pilot in me that's got me searching for some hard numbers. Still trying to learn as much as I can about the homebuilt world. As much as I appreciate the anecdotal accounts and the TLAR method, it would make me feel a lot better if I could at least have some consistent numbers or experiences from pilots operating in those ranges, or similar to what I have planned, before making such a substantial investment in time and money.

Speaking just for myself and not for other builders, I haven't compiled very precise takeoff data because I haven't needed it. I'm based on 2000 feet of grass, one way in and one way out. At max gross weight I use half of it on the takeoff, and a quarter of it on the landing. At typical weights without any flaps or effort, I'm off in around 400 feet of ground roll. That's with a 360 and nothing special in the pilot category. If I try harder I can use less, and have operated a couple of times from a friends much shorter strip. I've also been to a 1000 foot strip, one way in and one way out, with a strong tailwind on takeoff. It was a little sketchy. Similar to weight and balance, I don't make an explicit calculation for every flight. But if I'm going to be stepping out of my usual mission and loading the plane from floor to ceiling, then I certainly want to weigh things and add it all up.

What are hard numbers? A GAMA POH style takeoff performance chart? I certainly wouldn't bet my life on one of those. The E/A-B world is different than the type-certificated world. The airplane may not come with a takeoff performance chart, but you can make your own. You can see what Battson or Pat Fagan can do with a 540-powered Bearhawk in the backcountry, but how does that relate to what you'll be able to do? If you want to operate into strips where it really matters if your takeoff distance is 246 vs 484 feet, you aren't going to be there on your second flight. You'll be there after extensive proving and practicing. You'll establish norms based on your specific airplane and abilities. There are absolutely other homebuilt options that will get you on and off the ground quicker, such as the Super STOL. But they will not carry the kind of load that we can. Defining the mission is crucial. Is the takeoff roll the absolute most important factor? Or do you need to be able to carry a certain number of people or a certain amount of gear?

I know it's natural at the shopping phase to focus on the numbers, because numbers can be easy to get your hands on. They seem objective, though unfortunately they are usually not. But if it was possible to spend some time in a flying airplane, I think you'd be able to get a more holistic evaluation of performance, control harmony, comfort, and other factors that would be far more valuable than a chart that any of us could draw for you about how long the takeoff roll is. I usually have an open invitation for anyone who wants to go for a ride, but at the moment I guess we have to do the social distancing thing, and also being a 360-powered airplane, it may not be as valuable as getting to visit a 540.

[jaredyates]

I think we disagree about whether there are any real-world numbers, and what real-world numbers are. I think the numbers that are available are within the tolerance of noise that is going to vary from one plane, pilot, and airport to the next. Less than 500 feet at low DA, less than 1000 at very high DA. Landings on par with takeoff roll. I think we should be talking more about the mission requirements. Does the airplane need to be a homebuilt? That would rule out a Helio or C-185. Since we're talking about high DA, can it be a turbo? Is there any airplane on the market that can perform any better, and if so, is there anything the Bearhawk can do that the other plane cannot? In plane shopping or any shopping, we have to select from the available choices, not from an impossible ideal.

[zkelley2]

Well, since to my knowledge no one has even attempted to make numbers, no we don't. We have a good handful of anecdotes. You can control for pilot and it's easy to adjust for DA with math. If you couldn't every certified plane wouldn't have a POH with all those number in them.

The best we can do is say, well this guy with his plane can do this, and this guy can do this, and these numbers are as much as 200% from each other.
I guess you could take the worst of them and say it can do this, sometime better.
If you do ever over run the FAA can certainly use 91.103b to come after you.

[Russellmn]

Part of why the numbers are all over the place in the EAB world, and specifically in the Bearhawk world, is the vast differences in builds. One guy goes ultra light with a 360 and no electronics while another guy goes 540 and IFR ready. One guy has a stripped down interior and another has leather and carpet, etc... I think the best we can do is find one similar to what we would want and see what it's performance is like and then decide if that is sufficient for our mission.

[jaredyates]

Getting out of the comments and back to a regular reply, what separates data from anecdotes? What would the test program need to look like? Not trying to argue for the sake of arguing, but rather to understand wat you mean.

[zkelley2]

Anecdote was the wrong word. We have a scatter plot of data, that is just all over the place in which you can't really draw too much of a conclusion from, certainly nothing like you can with a piper or cessna or maule.
Ideally what data would look like is for a handful of people go out and measure takeoff and landing distances in 100lb increments, get an average at each weight, correct it for DA, wind, slope and then average that with other people doing the same thing. You'd have to single out things like VG's and engine, and then still look at the plot of results and do math to figure out outliers. We'd then have something closer.
Ideally everyone would be doing this for their own airplane anyways and all we would need is them to post their results. It's in the EAA flight test manual, which a lot of people use as their program letter. Which means we really should have this data.

[Daywalker]

zkelley2 commented
04-13-2020, 09:28 PM
The reason he want's to know if it's going to take him 250ft or 750ft is because he doesn't want to find that out after he takes 3-10 years and 100k to build it to only find out it won't do what he wants.
It would be amazing if we had some real world numbers. And the only reason we don't is because no one has taken the time and fuel to do it. Very achievable goal

Yes exactly, thank you.

jaredyates commented
Yesterday, 06:51 AM
I think we disagree about whether there are any real-world numbers, and what real-world numbers are. I think the numbers that are available are within the tolerance of noise that is going to vary from one plane, pilot, and airport to the next. Less than 500 feet at low DA, less than 1000 at very high DA. Landings on par with takeoff roll. I think we should be talking more about the mission requirements. Does the airplane need to be a homebuilt? That would rule out a Helio or C-185. Since we're talking about high DA, can it be a turbo? Is there any airplane on the market that can perform any better, and if so, is there anything the Bearhawk can do that the other plane cannot? In plane shopping or any shopping, we have to select from the available choices, not from an impossible ideal.

In regards to the mission profile, sure I'd love the distances a superstol or a cub variant can pull off, but I also don't want to be doing two or three round trips for the same bulk loading I could do in one bearhawk flight. So therein lies the compromise, which is fine because I don't quite need that STOL ability. But being able to get down to 500' distances while fully loaded, and shorter when lighter would be ideal.

As for the pilot skill comments sure, I totally agree that a sufficient amount of hours on type is a requisite for becoming proficient enough to operate in any tighter environment. That being said, and please don't take the following as condescending or arrogant because that's the last thing I like to come off as; but having flown "in the bush" in Northern Canada and the arctic out of sketchy strips for years, I'm somewhat confident I can become proficient enough in time to comfortably operate the bearhawk into some shorter strips, so long as it is capable of doing so. And no, I don't think it would be wise for a pilot to attempt it in any plane on their second flight, and in some cases even after a couple hundred flights.

As for the value of performance charts, it may be a tad bit controversial to me personally too because although I still prefer flying by feel and getting used to just knowing what an aircraft can or can't do from experience, I have in fact "bet my life" in one way or another countless times in various situations throughout my career and continue to do so, on performance charts. As is the case for thousands of pilots every day. Granted that's usually on much higher performance aircraft in a more highly regulated segment. Perhaps one really good way of looking at charts, at least for me especially when starting on a new type, is to have them as reference for what the airplane is capable of doing; (wherein most manuals spell out the technique used, and using average piloting skill) which may be made as a goal for some pilots to meet or even exceed.

I have looked at certified aircraft, and haven't ruled them out completely yet, but I'm pretty sold on the benefits of having a homebuilt, and really do want the satisfaction and challenge of the build. There are a few other contenders, but so far a 4-place is in the lead. I'm maybe a bit surprised there aren't some charts available or no one has tried to make some up given the amount of aircraft now flying out there but then again homebuilts aren't my world, but I'm still trying to learn as much as I can. Could be an opportunity for adding attractiveness to potential owners if they were available in the future. I agree, I think they'd be pretty straight forward to produce, just time consuming and finding willingness and know-how on extrapolating the data might be tricky.

Sorry for the novel, I guess if there aren't any charts available one of the next best things is personal accounts from pilots, so please keep them coming as I still appreciate hearing them.

[Mark Goldberg]

You ought to go find a flying BH and get a ride. See for yourself what the plane is capable of. Mark

[Daywalker]

Hey Mark, I did in fact go for a ride in one. It was good, but not under the conditions I was hoping for. Hopefully once this covid business ever cools off I can go visit Mike in Sask to see some more.