RCU Forums - BobCat downthrust?

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Haldor

10-21-2005 06:58 PM

BobCat downthrust?

Hi guys.

I'm doing some preliminary CAD work for a DIY "BobCat" and was wondering if the BVM BobCat have the turbine dialed in with some downthrust? I would assume there is but how much?

Also whats the wheelsize used on this jet, for gras ops? From the 3views the mains seem to be ~60mm.

Any help would be appreciated.
Haldor
www.halair.com

Silver182

10-22-2005 08:57 AM

RE: BobCat downthrust?

Quote:

ORIGINAL: Haldor

Hi guys.

I'm doing some preliminary CAD work for a DIY "BobCat" and was wondering if the BVM BobCat have the turbine dialed in with some downthrust? I would assume there is but how much?

Also whats the wheelsize used on this jet, for gras ops? From the 3views the mains seem to be ~60mm.

Any help would be appreciated.
Haldor
www.halair.com

I suggest you write Bob and ask him, your doing electric versions of different aircraft so it's possible he will give you all the data & info you want.

AVIOJET

10-22-2005 12:54 PM

RE: BobCat downthrust?

Haldor, the BobCat has about 4 degrees downthrust and 2 positive degrees on the stab.

BR

Jesus

Haldor

10-22-2005 03:13 PM

RE: BobCat downthrust?

Gracias Jesus :)

So the stab is set to +2deg relative to the wing? Would account for some of the high pressure area (exhaust) under the stab.

Info much appreciated!
Haldor

AVIOJET

10-22-2005 05:16 PM

RE: BobCat downthrust?

Haldor, all the angles are refered to the wing airfoil axis. To be honest I never understood wery well this set up, but my BobCat with a P-120 doesn't experiment any changes in fly at full or at idle.
Sorry I can't help more in this question I am not expert in aerodynamics.

BR

Jesus

Haldor

10-22-2005 06:05 PM

RE: BobCat downthrust?

Your info is plenty so no worries. Getting everything in the ballpark is the best I can hope for :)

Cheers,
Haldor

Haldor

10-25-2005 11:13 AM

RE: BobCat downthrust?

BTW what is the aluminum tube diameter/thickness? The ones that support the wing.

AVIOJET

10-25-2005 11:59 AM

RE: BobCat downthrust?

Harald, the front tube is 7/8" and the rear 3/8". I don't know the thickness because my BobCat is scratch built from plans and I have fitted 22 mm. and 16 mm. with 1.5 mm w.t. I guess that the english size is about 1 mm. w.t.

BR

Jesus

Haldor

10-26-2005 04:50 AM

RE: BobCat downthrust?

Excellent, thank you! :)

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