Pod installation

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Postby JPXman » Wed Mar 30, 2005 4:57 pm

do you have a picture of your pod installation yet? a common problem with fairings on aircraft directly in front of the tail is tail blanking.

how flat is your windscreen? if its not streamlined perhaps it is aerodynamically blanking out the tail, leaving only turbulent flow for the tail to fly through. i'd be careful if the pitch tendency is down, as that is a sure sign of tail blanking. this is why lots of light twins with a short fuselage have a high T-tail, to get the tail in clean air when at a high angle of attack. something is fishy. must be totally unnerving as the addition of power increases the pitch over...
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Postby Guest » Thu Mar 31, 2005 7:58 am

Unfortunately, I've misplaced my photo's. But my pod installation is identical to the White and yellow one Shannon posted on the previous page. I hadn't considered the blanketing effect of the pod. Perhaps that explains the tail shimmy that develops from time to time. I wonder if I should lower the rear portion of the pod so that the pod base creates a lifting force to counteract the downward force on the windscreen.

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Postby rayjb60 » Thu Mar 31, 2005 12:05 pm

Maybe you weigh more as well making the Lazair nose heavy, just makes the tail blanking pitch down even worse.

Check the weight and balance to make sure you are in the proper CG range with you in it.....trim tabs should not be used to compensate for an out of CG balance condition, as you are jeopordizing controlability.

My 2 cents

Ray
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Postby Guest » Thu Mar 31, 2005 12:13 pm

Pretty sure that I'm in the C.G. range. I weigh 170lbs. My installation is almost identical to the white and yellow pod that Shannon posted on the first page. I wonder if anyone else with Mike's pod has had a similar symptom? I installed it exactly how Mike recommended.

Brian
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Postby bdiedenhofen » Fri Apr 01, 2005 9:49 am

Thanks for the thoughts. I've attached a photo of CUN with the pod installed. It was installed as per Mike's instructions. I weigh 175 lbs, so don't think it's a weight and balance issue. In previous posts, Shannon mentions that his pod has a similar symptom, (nose down tendancy due to wind force on the windshield). He corrected it with trim tabs. My concern is that as the speed increased, the downward force becomes more noticable. It's a negative pitch condition that does overcome the trim tabs in certain situations. I do not want to frighten anyone away from Mike's pod, it's fabulous. I just want to see if anyone has had a similar symptom and if there is a solution that I haven't figured out yet. I think that I may try lowering the aft portion of the pod thus creating a lifting force that should counteract the downward force of the windshield. In theory, this should resolve the need for trim tabs altogether once the correct angle has been established.
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Postby bdiedenhofen » Fri Apr 01, 2005 10:01 am

Thanks for the thoughts. I've attached a photo of CUN with the pod installed. It was installed as per Mike's instructions. I weigh 175 lbs, so don't think it's a weight and balance issue. In previous posts, Shannon mentions that his pod has a similar symptom, (nose down tendancy due to wind force on the windshield). He corrected it with trim tabs. My concern is that as the speed increases, the downward force becomes more noticable. It's a negative pitch condition that does overcome the trim tabs in certain situations. I do not want to frighten anyone away from Mike's pod, it's fabulous. I just want to see if anyone has had a similar symptom and if there is a solution that I haven't figured out yet. I think that I may try lowering the aft portion of the pod thus creating a lifting force that should counteract the downward force of the windshield. In theory, this should resolve the need for trim tabs altogether once the correct angle has been established.

Brian
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Postby Guest » Fri Apr 01, 2005 2:41 pm

Experiment a little:

Put more bend in your trim tabs
Move your seat back a little (Check CG too)
Check tension on your tail cables (10lbs ea)
Check you ASI against a GPS
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Postby Guest » Fri Apr 01, 2005 2:42 pm

Experiment a little:

Put more bend in your trim tabs
Move your seat back a little (Check CG too)
Check tension on your tail cables (10lbs ea)
Check you ASI against a GPS
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Postby Guest » Fri Apr 01, 2005 4:04 pm

Experiment a little:

Bend the trim tabs a little more.
Check your tail cable tension (10lbs) and check rudder deflection limits.
Compare your ASI reading against GPS (faulty ASI numbers)
Do a CG check.
Move the seat back a little possibly.
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Postby Guest » Sun Apr 03, 2005 7:43 pm

Experiment a little. Check your ASI against a GPS. Try a little more bend on your trim tabs or install bigger ones. Shifting the seat back a little may help. Plane could use some P-tips, pants, and spinners. Very nice anyway.
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