Backcountry Pilot • 4-place Bearhawk vs 4-place Just Aircraft Super STOL

4-place Bearhawk vs 4-place Just Aircraft Super STOL

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4-place Bearhawk vs 4-place Just Aircraft Super STOL

Just aircraft recently announced a new " Stretched Version" of their Super STOL that is 2 1/2 feet longer and adds a 180 HP UL six cylinder engine. They call it the Super STOL XL .

If Just Aircraft decided to produce it, would a 4-place Super STOL "XL4" make sense?

The 4-place Bearhawk is a truly classic design that balances speed, STOL, cockpit space, and a truly innovative Riblett airfoil. It has a 33 ft. wingspan ( 180 sq. ft.), 42 inch wide cockpit, and a. length of 23 1/2 ft. Not LSA. Lovely plane.
Image


Just Aircraft in South Carolina recently “stretched” their Super STOL model by 2 ½ feet. The result is the Super STOL “XL” model which appears to have a 31 ¼ ft. wingspan ( 147 sq. ft.), a 44 inch wide cockpit, and a length of 22 ½ ft. Lovely plane as well, with kick-ass STOL characteristics at the expense of some speed. Oh yeah, it also has folding wings. Still LSA compliant if builder so chooses.
Image


Perhaps a 4-place Just Aircraft Super STOL is quietly being considered in the skunkworks down in Walhalla, SC ? Call it the Just “XL-4” . Obviously if no longer bound by LSA 1320 lb. gross and other limitations, a light & nimble 4-place Just Super STOL would be an interesting alternative to a Bearhawk for pilots seeking more STOL and less speed capability. The Back Country Cubs Boss SQ4 is another alternative competitor that also comes to mind (not LSA).
Image

So, ditch the LSA, add another 6 - 12 inches to the fuselage, maybe ditch the folding wings and make them a little longer, and refine a few other things. Then perhaps a 4-place Just EAB non LSA aircraft is not that much of a pipe dream. I respect both the Bearhawk and the SQ4 , but a little extra competition sometimes is not a bad thing.

So…. would a 4-place Just Super STOL “XL-4” make sense? Given Just Aircraft's success to date, is there a sufficient market for a Just 4-place Super STOL to be successful?
Last edited by Denali on Sun Apr 05, 2015 9:14 pm, edited 2 times in total.
Denali offline
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

I personally love the idea!! IF i had the money I would have a SQ-4 sitting in my driveway...... and life would be GOOOOOD! :D Bring on the
XL-4!!!! The SuperSTOL is such a cool plane :D
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

The Bearhawk will go 150 mph. 8-)
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

Denali wrote:......and a truly innovative Riblett airfoil.


I don't think Bob introduced the Riblett airfoil until the Patrol. The Bearhawk is essentially a NACA 4412.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

@ Onemilehigh:

You are absolutely right. I stand corrected. From the Bearhawkaircraft website:
http://bearhawkaircraft.com/Bearhawk/BHdescription.php
... ALL METAL WINGS WITH LOTS OF FLAPS
The modified 4412 airfoil combined with big flaps and a long, all metal wing offer the best combination for short field take off and landings. ...
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

@ Onemilehigh:

You are absolutely right. I stand corrected. From the Bearhawkaircraft website:
http://bearhawkaircraft.com/Bearhawk/BHdescription.php
... ALL METAL WINGS WITH LOTS OF FLAPS
The modified 4412 airfoil combined with big flaps and a long, all metal wing offer the best combination for short field take off and landings. ...

@ZZZ
From the Bearhawk website the 150 mph seems to be for the 250 HP equipped BH, not the 180 HP. But I grant you the point, because if I were to build a BearHawk 4-place, I'd go for the larger 250 HP motor.
http://www.bearhawkaircraft.com/index.php/4placebearhawk/bearhawkspecifications
.... Useful Performance
• 250 hp -160 mph @75%-150 mph @62%
• 180 hp -145 mph@ 75 %-135 mph @ 60%
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

If I remember correctly Harry Ribblett worked with Bob on modifying the 4412 airfoil for the Bearhawk so your partly correct Denali.

The Superstol is a cool airplane and a 4-place version would be even cooler. But if I boiled down my purpose for an airplane to two things it would be: 1. To get places faster. 2. Go places I wouldn't go if I didn't have an airplane. The Superstol will go places I wouldn't go without a plane but it won't get there very fast. If your all about STOL a XL-4 or a SQ-4 would be the plane for you. I wanted a 130mph airplane with reasonable STOL abilities which is why I ended up with a Bearhawk.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

I built and flew for 40 hours an 0-320 powered Avid Magnum (just like the name would lead you to believe). It got off short and climbed real good, but all that extra weight hurt the short field performance big time. It landed high 40's, period.That 180 UL is 180 only once at 3200 rpm, least we forget. Take a good look at that Bearhawk wing, it's huge (relatively), with a very deep chord, heck the control surfaces are almost as big as the SS wing (exaggerating), point being loading that plan form up with more and more weight can't help the short field performance. Take off yes, landing, not so much. Comparing the two designs is an apples and oranges kind of thing it seems to me, and not really fair to either designs performance goals.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

courierguy wrote:Take a good look at that Bearhawk wing, it's huge (relatively), with a very deep chord, heck the control surfaces are almost as big as the SS wing (exaggerating), ...


Bearhawk flap next to an RV-4 wing. :shock:

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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

whee wrote:If I remember correctly Harry Ribblett worked with Bob on modifying the 4412 airfoil for the Bearhawk ...


Bob once told me that Harry recommended a change to the 4412 that blended the intersection of the nose circle with the top (and/or bottom?) surface. Didn't sound like a collaboration to produce a significantly modified airfoil. ...more of a fixing of the airfoil due to issues of how NACA defines its airfoils.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

Denali wrote:... a truly innovative Riblett airfoil.

I'm not sure if the Riblett has been shown to be truly innovative. Side by side comparisons of identical builds aside from the airfoil show virtually identical performance at every speed. It is hard to hang performance on the specific airfoil shape past a certain point for light airplanes- and I seem to recall that Barrows has noted exactly this in his BH write-ups somewhere.

On the other hand, there may be subtle advantages in the stall characteristics, but more often these characteristics are addressed in wing design rather than airfoil design. I believe Riblett claims lower trim drag from his modified NACA shapes, but so far the actual as-built differences appear to be either too subtle to notice/care about.

Both the BH and the SS are are cool planes for different missions, though. .
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

lesuther wrote:
Both the BH and the SS are are cool planes for different missions, though. .


This^^. They are different caliber machines, different missions, and only one actually exists. 8)
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

I read a post (from the BH Yahoo group) a while back from someone who was building a Bearhawk wing based on a Ribblett foil (Maybe from the Patrol?) I can't remember his name or location, but he described the many challenges of straying off the plans :D Would be interesting to know if it was ever finished.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

++1 Zzz
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

kestrel wrote:Bearhawk flap next to an RV-4 wing. :shock:
Image


This is a good example of "a picture's worth a thousand words". Very graphic comparison.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

A guy I know got interested in the Just SS when it was first introduced, but he wanted something that could accommodate a Lycoming engine. He called & talked to them and asked about hanging a 320 on the SS-- nope, too heavy. They told him they had hopes of producing a larger version, but they were so busy keeping up with the demand for current kits they didn't know when they'd be able to. I was kinda surprised to see the new larger version announced so soon...... unless maybe they're just testing the waters re demand before getting too involved in production. I've seen gun mfr's do that-- introduce a new model, and if demand isn't high enogh they never actually produce any.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

The SuperSTOL looks like fun for an afternoon, but with a load on things change....

Apparently you need 400ft to take-off with a full load, only 250ft to land, but take off limits where you can practically land to 450ft-500ft strips if you are carrying gear. That payload is limited to 570lbs useful, before you subtract the pilot, fuel, tools & tiedowns, etc. Yes can fly at 28kts, just not in the three point attitude, which I assume the hinders take off.

A SuperSTOL XL would only provide an honest advantage as a practical backcountry aircraft if the horsepower is jacked up enough to considerably reduce the take-off distance, without adding weight and lengthening the landings further.

The Bearhawk is on the other side of the same see-saw, heavier but also more powerful. Last weekend we had a little over 570lbs of people, fuel, and gear aboard. We needed 400ft to land with no wind and basically zero braking on frosty grass. About 200ft to take off. But we're still getting the same 570lb payload in & out of the smallest strip a SuperSTOL can (according to the published performance), except we're limited by landing distance.
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Re: 4-place Bearhawk vs 4-place Just Aircraft Super STOL

Could not agree more, H.Riblett was a great guy, but he missed that 2D computer models of airfoil, although revolutionary at the time where still bound by the limits of 2D theory and the approximations where not always viable for a 3D wing, much less prove 100% behaviour (notice I did not use performance) on a 2D airfoil theory. That is a fact for all airfoils, not just Riblett. Are they bad airfoils, no, are they better than x, for certain X airfoils they certainly provide better behaviour, and is that's you propose, then yes. Now, will they provide more lift like it was claimed, certainly this is a very grey area in aerodynamics, and so far, there has been no single proof that this is certainly the case, win tunnel 2D or 3D tested. Did he fix some behaviour from the NACA 4 series, yes, is that better, it depend.... and we can continue on and on.

If you are looking for STOL, then your have to consider two factors, CL_Max of your wing configuration and wight, and then it's all about wing loading and power the weight ratio, no way you can move out of those constrains, as this influence is directly responsible for your Take Off performance. Landing is a combination of when're the Cl_Max is produced vs the attitude go the airplane and weight (and most important the pilot to take it to the leading edge).

I think the conversation would be most interesting from a objective approach to consider the benefits of either BH or the Super Stol around your own needs and piloting skills. Then you can focus on how each of those airplanes could be improve to move then in the direction of each pilots needs. Comparing one vs the other or x foil vs another will lead us to a bias discussion about what each of us favours. As an example of that bias, I'll kick it off with my own bias observations:

- I like Stol, getting in and out of tight places, for that feat alone, than single piloting is the best approach and the Super Stol is a great platform. If you are consider greater performance, look at what the Breeden's have done, extended the cord, and looked for maximum CL_max with a light airplane behind a very powerful platform. That's a new class of airplane, and yes it looks like a cub so if you are into that look, great! I dig it, and Bobby is a kick ass pilot. Then there is Lil'Cub, and man, I would love to fly the airplane.... Frank is not very far behind Bobby, and I sure would love to see those two in actions.

Now, if you need to haul you family around, and consider getting into some tight (not extremely tight) places for camping, the BH is a great platform. I'm bias in believing that the Cub wing (keeping cord and span from the original design of the BH) will make this a better performer for Stol, and if you consider that the best Stol improvement to the cub platform has been Mackay's Slats, then adding those will certainly get you sorter while keeping you safer doing it. Now speed will not be all that bad, sure you will loose some performance, but considering that this is still a draggy platform, you will not impact it more that 10-15% overall, so it's something to consider. If I owned one, I certainly would design slat for them.

Now, from imprecise data (all the test done out there), nothing makes a better platform than a fine tuned 23012 + Slat (CL:Drag improvements at the loss of CL_Max, you go a little faster, but land a little longer) or a Goe 387 + Slat ( CL:Drag is in the 38, so forget about exceeding 100mph, but you can hang your plane on the wing when you put it on your hanger :D :shock: )

Will either of those improve the Cub, BH, or Super Stol, you have to try it out to see... but most likely you can expect behaviours similar to those that used that framework to build an airplane.

Hopefully I will not shot at, but I do enjoy the discussion.


Cheers! and I hope my souther friends are safe from hurricane!
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