Angle of incidence of center tank on a BobCat?
12-24-2008, 10:23 AM
#1
Angle of incidence of center tank on a BobCat?
Hi guys,
How are you guys mounting centerline tanks (or wing tanks for that matter) in terms of incidence?
My guess would be to run the tank at maybe 1 to 1.5 degrees negative so that it is running at zero angle of attack (or close to it) at cruise speed?
What are you guys doing?
Thanks,
How are you guys mounting centerline tanks (or wing tanks for that matter) in terms of incidence?
My guess would be to run the tank at maybe 1 to 1.5 degrees negative so that it is running at zero angle of attack (or close to it) at cruise speed?
What are you guys doing?
Thanks,
12-24-2008, 10:33 AM
#2
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RE: Angle of incidence of center tank on a BobCat?
I have no idea what the angle is for the tanks on my prehistoric Bobcat !
If you have a choice in your (presumably ARF?) Bobcat, I'd personally want the bottom of the tanks to have a degree or two of positive incidence when the wings are level ... that way the fuel naturally pools to the low-point where the clunk can get every last drop ; if the tank floor is completely level there is no pooling, so presumably you'd suck air sooner ?
The above opinion is nothing scientific - simply gut-feel (without coffee yet, so possibly nonsense!!)
Gordon
If you have a choice in your (presumably ARF?) Bobcat, I'd personally want the bottom of the tanks to have a degree or two of positive incidence when the wings are level ... that way the fuel naturally pools to the low-point where the clunk can get every last drop ; if the tank floor is completely level there is no pooling, so presumably you'd suck air sooner ?
The above opinion is nothing scientific - simply gut-feel (without coffee yet, so possibly nonsense!!)
Gordon
12-24-2008, 11:16 AM
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RE: Angle of incidence of center tank on a BobCat?
In the old BC, the tanks are held in place by their shape in the wings and hence are preset. In the Composite, they are monuted in a similar fashion as in the Kingcat. So their position is pretty much set by design...
12-24-2008, 12:43 PM
#5
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RE: Angle of incidence of center tank on a BobCat?
Ah - ok ... when you mentioned wing-tanks, centre-line etc, I totally misunderstood and thought it was like the old Bobcat where the main tanks are 'wing-tanks' coz they fit inside he wing, and "centre" tanks because they are in the centre-section of the wing rather than the outboard sections. My bad.
Oh well. In that case I imagine a zero aerodynamic incidence in level flight would be best, so as to not impart any pitch effect on the aircraft.
Gordon
Oh well. In that case I imagine a zero aerodynamic incidence in level flight would be best, so as to not impart any pitch effect on the aircraft.
Gordon
12-24-2008, 02:12 PM
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RE: Angle of incidence of center tank on a BobCat?
ORIGINAL: mr_matt
External tanks, Ehab :-)
External tanks, Ehab :-)
.. Well, you fooled Gordon and myself....So like you said, a negative .5 to a degree will be perfect. I am running two wing tip missles on my RARF at zero degrees and see no ill effect, but I think the BC is a wee bit different[8D]
12-24-2008, 04:02 PM
#7
RE: Angle of incidence of center tank on a BobCat?
Matt,
To answer your question, I dont know. However, when I built mine I also purchased the pylon kit from BVM which set the incidence of the tank for you. Later today I will install my tank and throw an incidence meter on it for you. Maybe a couple of pics might help you as well.
To answer your question, I dont know. However, when I built mine I also purchased the pylon kit from BVM which set the incidence of the tank for you. Later today I will install my tank and throw an incidence meter on it for you. Maybe a couple of pics might help you as well.
12-24-2008, 06:51 PM
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RE: Angle of incidence of center tank on a BobCat?
hi matt we are talking about the bvm bobcat if so just put them as instructions it matters not if you run a uat my old balsa bobcat has two wing tanks that feed another tank that is on the wing in the center then that goes to the uat the fuel will be sucked to the uat where ever you put the tank hope this helps regards jonathan
12-24-2008, 07:17 PM
#9
RE: Angle of incidence of center tank on a BobCat?
Matt,
after measuring 4 different times, using a standard and digital incidence meter, I keep ending up with -1 degree. Couple of pics to look at as well. Hope this helps.
after measuring 4 different times, using a standard and digital incidence meter, I keep ending up with -1 degree. Couple of pics to look at as well. Hope this helps.
12-25-2008, 05:27 PM
#10
RE: Angle of incidence of center tank on a BobCat?
Hi guys,
I read my post again, I could not have made the tank reference more ambiguous if I tried!
Anyway, Ad that is the info I am looking for. Also, what is the depth (height?) of that centerline pylon (I never got any plans for the, just the tank BTW) and how far aft is it mounted? I am trying to get teh CG of the tank in line with the CG of the plane but that puts it pretty far aft (as an eyeball approximation).
Say "hi" to your dad for me, and Merry Christmas.
I read my post again, I could not have made the tank reference more ambiguous if I tried!
Anyway, Ad that is the info I am looking for. Also, what is the depth (height?) of that centerline pylon (I never got any plans for the, just the tank BTW) and how far aft is it mounted? I am trying to get teh CG of the tank in line with the CG of the plane but that puts it pretty far aft (as an eyeball approximation).
Say "hi" to your dad for me, and Merry Christmas.
