TIGHAR

Amelia Earhart Search Forum => Aircraft & Powerplant, Performance and Operations => Topic started by: Jeff Victor Hayden on July 06, 2012, 12:57:37 PM

Title: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: Jeff Victor Hayden on July 06, 2012, 12:57:37 PM
I woulld like to add at this stage the substance of the debate regarding the bouyancy of the Electra.
So we're pretty close to Howland, good.
Our box search pattern is in place, good.
Visibility not bad, good.
SAR tables in our favour, good.
We're out of gas and in the water but, they'll find us, see the previous 4 points
Bouyancy? If I recall from the thread it was theorised that the Electra would remain afloat for some considerable time due to the empty fuel tanks, see previous 5 points.
How did they miss us? Bad
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: John Ousterhout on July 06, 2012, 04:17:38 PM
We don't have enough information about the fuel tank designs to be certain the Electra would float. Perhaps AE/FN assumed it would float, flew some sort of search pattern to fuel exhaustion and ditched close to Howland, but were wrong in their assumption of long-term buoyancy.
Does anyone know of any statements by AE about the aircraft's ability to float or sink?  If she said something about it, it might be a useful clue to our guesses about their actions while searching for Howland.
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: C.W. Herndon on July 06, 2012, 05:29:25 PM
I think GL did some calculations about that. I'm sure he will direct everyone to the correct place as soon as he is able.
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: Gary LaPook on July 06, 2012, 09:49:06 PM
I think GL did some calculations about that. I'm sure he will direct everyone to the correct place as soon as he is able.
Try:

https://tighar.org/smf/index.php/topic,481.msg6010.html#msg6010

and

https://tighar.org/smf/index.php/topic,481.msg6099.html#msg6099

It is really difficult to figure out the attitude of the plane when afloat because of the complicated shape. The part of the plane that is immersed provides buoyancy while the part above the water forces the plane downward and the shape of the immersed section changes as is sinks deeper. The plane will tilt until the center of buoyancy is directly above the center of gravity. We know where the COG is but it is hard to locate the COB as the plane is immersed.
gl
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: Jeff Victor Hayden on July 07, 2012, 05:36:19 AM
Gary
Has the possibility that all the modifications and extras added to the model 10-E special might have some effect on the flying characteristics of the aircraft when not under power e.g. When gliding due to fuel starvation?
When the Electra was designed it was never intended to be a flying laboratory. The 10-E special would have been tested with all the modifications of course, under power?
Could all of these modifications altered the COG? Trim characteristicts? Probably not noticeable
when under power but when dead stick?
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: C.W. Herndon on July 07, 2012, 07:17:34 AM
Thanks Gary. That's the explaination I remembered. I just could not remember where it was. Part of that old age?
Title: Re: L10E bouyancy (split from LaPook Hypothesis: Box Search around 157-337)
Post by: Gary LaPook on July 07, 2012, 02:38:14 PM
Gary
Has the possibility that all the modifications and extras added to the model 10-E special might have some effect on the flying characteristics of the aircraft when not under power e.g. When gliding due to fuel starvation?
When the Electra was designed it was never intended to be a flying laboratory. The 10-E special would have been tested with all the modifications of course, under power?
Could all of these modifications altered the COG? Trim characteristicts? Probably not noticeable
when under power but when dead stick?
The center of gravity range of the Electra and all aircraft is one of the most (maybe THE MOST) critical part of the design. Earhart's plane had a CG range of only 14.55 inches, 11.65 inches forward of the spar to 2.9 inches aft of the spar and it must remain within this range for all load conditions, full tanks to empty. This is what drove the placement of the ferry tanks.

So, to answer your question, no, the plane would have flown like a normal L10E except the takeoff and climb performance would not be as good whenever the plane was operated above the normal maximum gross weight of 10,500 pounds and the stall speed would be 19% faster at 15,000 pounds than at 10,500 pounds.

gl