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  #61  
Old 06-03-2021, 06:45 AM
Paragon Paragon is offline
 
Join Date: Jul 2014
Location: Cincinnati, OH
Posts: 79
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That pod is looking better and better as you tweak.

One more possibly helpful comment:

If the pod closeout is not extended sufficiently far to fully prevent flow separation, then one probably wants to terminate the pod closeout with an abrupt, blunt, rectagular trailing edge (or in 3D, trailing face), rather than a rounded or ramp-like shape. (VG's a few inches upstream can extend the separation point farther around a turn, but what's shown here will presumably still separate at some location.)

Why an abrupt Trailing Edge?

What one does not want is a vague separation point. There may be some airspeed range where the flow separation is unstable, hence inducing loud vibration into the airframe. It would be better to close out the pod as much as possible without flow separation, then abruptly cut it off so the separation point is fixed at that location.

-Paragon
Cincinnati, OH
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  #62  
Old 06-03-2021, 07:53 AM
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Steve Melton Steve Melton is offline
 
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Location: Cincinnati, OH
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Quote:
Originally Posted by Norman CYYJ View Post
Steve, why not make the bikes mount on a belly door and swing it up into place in the pod?
it could be done that way but you would need to climb under the aircraft to load the bikes on the swing tray and then lift the 75 lbs of bikes to attach the swing tray to the pod. the aerodynamic loads on the bottom of the tray is 170 lb downwards, so 75 + 170 = 240 lb the hinge would need to support in cruse flight with no g loading. I feel better about having the bikes totally enclosed in a rigid box.

Pod corner brackets note: in cruise flight with no g loads the four corner brackets of the pod will need to support on average, total pod weight =130, aero load = 170 , 300/4 = 75 lbs each. add 4.4g to the pod + bike weight = 130 x 4.4 = 572, add aero total for total max load = 572 + 170 = 742 lb., 742 lb / 4 = 185 lb avg max gust load on each corner bracket. and then you need to add some load for gasket cushion compress loading. 250 lb load is probably a good number to design the corner brackets.
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RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
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Last edited by Steve Melton : 06-04-2021 at 05:25 AM.
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  #63  
Old 06-03-2021, 08:09 AM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,255
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Quote:
Originally Posted by Paragon View Post
That pod is looking better and better as you tweak.

One more possibly helpful comment:

If the pod closeout is not extended sufficiently far to fully prevent flow separation, then one probably wants to terminate the pod closeout with an abrupt, blunt, rectagular trailing edge (or in 3D, trailing face), rather than a rounded or ramp-like shape. (VG's a few inches upstream can extend the separation point farther around a turn, but what's shown here will presumably still separate at some location.)

Why an abrupt Trailing Edge?

What one does not want is a vague separation point. There may be some airspeed range where the flow separation is unstable, hence inducing loud vibration into the airframe. It would be better to close out the pod as much as possible without flow separation, then abruptly cut it off so the separation point is fixed at that location.

-Paragon
Cincinnati, OH
yes, that's a good suggestion. I simply rounded the this one off. you can see the effects. I don't know if the movie will play.





movie

https://hosting.photobucket.com/imag...080&fit=bounds
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com

Last edited by Steve Melton : 06-03-2021 at 09:21 AM.
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  #64  
Old 06-04-2021, 06:12 AM
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emsvitil emsvitil is offline
 
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Location: SoCal
Posts: 556
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Don't forget G loads for the pod, not just normal weight and aerodynamic forces.....

How about pressure recovery on the rear section like the wheel pants.....
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  #65  
Old 06-04-2021, 08:32 AM
Norman CYYJ Norman CYYJ is offline
 
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Location: Victoria B.C.
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Instead of a pod on the belly how would a small pod on each side work out? Might not make any difference to the total drag component and you wouldn't have to bend over and fight putting the bikes underneath. Also no interruption of air flow for the engine cooling.
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  #66  
Old 06-04-2021, 08:52 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
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Quote:
Originally Posted by Norman CYYJ View Post
Instead of a pod on the belly how would a small pod on each side work out? Might not make any difference to the total drag component and you wouldn't have to bend over and fight putting the bikes underneath. Also no interruption of air flow for the engine cooling.
like Squirrel cheeks?
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #67  
Old 06-17-2021, 06:04 PM
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emsvitil emsvitil is offline
 
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https://www.flyingmag.com/story/airc...3XQtACS-1IjxMJ
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  #68  
Old 06-17-2021, 07:43 PM
Steve Melton's Avatar
Steve Melton Steve Melton is offline
 
Join Date: Apr 2011
Location: Cincinnati, OH
Posts: 3,255
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Quote:
Originally Posted by emsvitil View Post
Wow, that thing is huge.
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Steve Melton
Cincinnati, OH
RV-9A, Tip-up, Superior O-320, roller lifters, 160HP, WW 200RV, dual impulse slick mags, oil pressure = 65 psi, EGT = 1300F, flight hours = 900+ for all

Simplicity is the art in design.
I was born an airplane nut. I have no explanation for it.
My Artwork is freely given and published and cannot be patented.
www.rvplasticparts.com
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