To do 50 minutes, you would need prop efficiency to come into the 90% range.
Adding blades impacts the relative efficiency of the other two blades to some extent.
Sent from my iPhone
On Feb 11, 2014, at 1:51 PM, Phedon Tsiknopoulos <phedon21t_at_yahoo.com> wrote:
> How about a 3-bladed prop to reduce the unwinding speed, and head for 50 minutes.
>
> Sent from my iPhone
>
> On Feb 11, 2014, at 5:21 AM, "mkirda_at_sbcglobal.net" <mkirda_at_sbcglobal.net> wrote:
>
>>
>> Slobodan Midic has a design that does that already, as well as Dr. Drela's info posted here. There is still a lot of room for experimentation and optimization with those designs. Drela's design has one drawback in that it applies torque a typical design may not be able to overcome. Offsetting the wing further may help, as may limiting the largest diameter a bit more. The hinges are also critical. Spring design for closing also becomes critical as the change comes over 160 degrees.
>>
>> By all means, experiment with these designs.
>>
>> Regards.
>> Mike Kirda
>>
>> --- In Indoor_Construction_at_yahoogroups.com, Tapio Linkosalo <tapio.linkosalo_at_...> wrote:
>> >
>> > On Tue, Feb 11, 2014 at 12:36 PM, Phedon Tsiknopoulos
>> > <phedon21t_at_...>wrote:
>> >
>> > >
>> > >
>> > > What if we have variable pitch as well as variable diameter?
>> > >
>> > >
>> >
>> >
>> > Also that has been tried (change the pitch along changing diameter), but no
>> > break-through on that either. Probably you would need to have variable
>> > pitch distribution (VPD) prop for making the 50 mins.
>> >
>> >
>> >
>> > -Tapio-
>> >
>
>
Received on Tue Feb 11 2014 - 16:00:06 CET