GW 2700 vs 2750

[tailwind]

Looks like a curtain to reduce heated area.

[Archer39J]

Ha, I like the Bears on the yoke! Very nicely finished aircraft.

[MitchG]

Heading down to Edmonton in awhile, so will have a look at this one if still for sale.

[Bdflies]

Looks like a really nice plane! Let us know how it goes.

Bill

[kestrel]

His main elevator trim tabs are ENORMOUS. That thing will be super-sensitive to pitch trim.

That is the "early" version and what I have on mine. The issue was less the trim sensitivity and more the excessive "servo tab" behavior. I disabled one of my tabs.

[Camlawrence]

2,500 lbs is the maximum landing weight approved by Bob, for the Bearhawk 4 place land-plane.

If you land at a heavier weight than 2,500 lbs, there is a risk of bottoming out the suspension and bending the steel tube structure.

The 2,700 lbs is only a take-off weight, and you need to burn 200 lbs of fuel to land - which is not an insignificant amount of fuel. Or throw some gear out the window, whichever you prefer. If you were forced down by weather before you could burn the fuel, then the landing would be a delicate affair.

The plane feel heavy at 2,500 lbs, and at 2700 it's decidedly weighed down. You can feel the weight when you taxi. In my machine some doors need an extra push to shut securely (fuselage is flexing under the weight). The plane can take it, but my point is going over 2,700 lbs is not something to be taken lightly. No pun intended.

I,ve looked all over the forum pages and can’t find “Bob’s approval” to use 2700 lbs for a MTOW while keeping 2500 as the MLW. I would really appreciate some guidance on this, thanks.

[alaskabearhawk]

I looked in my old Yahoo Group archives about this and just gleaned a few comments from Budd Davisson about the MTOW of the Bearhawk. I also added the date of the replies. FWIW, I have never heard of anyone referring to the MTOW of the BH being 2750. Hope this helps:

6/26/2005

Bob has made it official that the takeoff weight is 2700 pounds and landing is 2,500 pounds with the front gear leg being the engineered weak link. However, as tire size goes up, shock absorption also gets better, so.... The airplane has been flown and landed at weights WELL above the numbers Bob states.

bd

9/2/2007

A Note about Useful Load comparisons
When comparing kits, please try to do an apples to apples comparison because many kits (and certified airplanes) quote their gross weight and useful loads at 5.8 G's (Normal Category) because it makes both gross weight and useful load bigger. Those numbers would be much lower at the 6.6 G's (Utility Category) to which the Bearhawk is designed and tested. Conversely, the Bearhawk numbers would be significantly higher if quoted at 5.7G's (Normal Category).

For comparison, a 1979 Cessna 172 has a gross weight of 2300 pounds in Normal Category but only 2000 pounds in Utility Category.

The Bearhawk wing has been load-tested to destruction to verify its ability to meet Utility Category limits (6.6 G's) but we do not quote Normal Category limits because we view the extra margin as a form of additional safety factor

11/5/2008

> The Bearhawk is utility category. The V-speeds are related to gross
> weight, no? How would Vne change if it were flown in normal category,
> and what would gross weight actually be at that category?

Vne isn't based just on weight. Flutter and other things figure in as well.
Although I've never asked Bob, I'm fairly certain he established Vne based on flutter test speeds rather than when it runs out of normal gust speed protection at a given G load, which is the other parameter.

Bob won't tell us it's normal category gross although you can get a clue in that he allows us to tell customers that takeoff gross is 2700 pounds but landing gross is 2500. This also validates your point below about the landing gear.

11/8/2008

The G loadings on the categories are on the wings, airframe, etc. These are set by the category (which actually doesn't apply to an experimental unless you want it to, and we do). The strength of the landing gear is not. Bob decided to make the landing gear itself the weak link so the back leg will fail before anything in the fuselage fails, thereby limiting the damage to the gear. The limits used are applied at 2500 pounds. So you can take off at
2700 pounds but have to land at 2500 pounds to still have all of the strength allowable (I'm assuming something around 4.0 G's, but I've never thought to ask him) he engineered the gear at. As the weight goes up, the strength of the gear goes down.

Does that make sense?

bd

[kestrel]

I looked in my old Yahoo Group archives about this and just gleaned a few comments from Budd Davisson about the MTOW of the Bearhawk.

He lists normal category as 4.8G's and utility as 6.6G's. This appears to be ultimate load (failure). Normal, utility and aerobatic category are generally 3.8, 4.4 and 6 G's with a 1.5 safety factor.

[Battson]

I,ve looked all over the forum pages and can’t find “Bob’s approval” to use 2700 lbs for a MTOW while keeping 2500 as the MLW. I would really appreciate some guidance on this, thanks.

That's just Bob's way. You won't find Bob writing a lengthy document explaining it, but the information is here.

I can promise you, I've called him and spoken to him about this at length, then written it down - and everyone else gets the same message when they call him.

[Bcone1381]

So, right now we can call Bob and get approval. The Bearhawk line of products will outlive Bob. How can Bob's Approval be formalized for the future builders? I wonder if Jared can grow this forum and Beartracks into Bearhawk Builders Group that can encompass things like that.

I think I'd like to have my Patrol MTOGW increase to 2200 pounds, MLGW 2000 lbs to improve utility. Since I've heard others have that approval I suppose I Can just go ahead and declare that now, or should call Bob?

[Battson]

As I understand it Brooks, you don't need Bob's approval in the USA - as the builder you can do whatever you like.

Those in the UK would need design approval, though. They have some of the strictest rules.

In NZ, we are halfway between the two, provided we have something supporting our decisions then I think we get to choose whether we go 2500 or 2700.

[Battson]

For avoidance of doubt, I can't comment on the Patrol gross weight. My knowledge is limited to the 4-place.