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Author Topic: Whats Eveyone Got Against Short Noses , ANYWAY .  (Read 467 times)

Offline Matt Spencer

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Whats Eveyone Got Against Short Noses , ANYWAY .
« on: July 06, 2017, 09:55:44 PM »
Says He after reribing the fin & Swiss Cheesing the rudder posts of a semi scale Typhoon , The Props about 10 in from the Mainspar / Center of Gravity . 8)

One Assumes Light Motors came about due to long noses being required , for fuel space and suchlike , after all , you dont see long noses on Combat wings . S?P

If One Could Cut the Nose Length IN HALF , wouldnt the Aeroplane Fly Better . Less polar moment of inirtia there & half the  Moment for gyroscopic precession

ETC ETC .


Offline Matt Spencer

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Re: Whats Eveyone Got Against Short Noses , ANYWAY .
« Reply #1 on: July 06, 2017, 10:00:07 PM »




Looks Like al rabes got a lot to anser for , here .  :## ;)

Offline Brett Buck

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Re: Whats Eveyone Got Against Short Noses , ANYWAY .
« Reply #2 on: July 06, 2017, 10:50:33 PM »
Less polar moment of inirtia there & half the  Moment for gyroscopic precession

   Yes on the first, no on the second - torque is torque, it doesn't matter where it is applied.

    The answer is that you make it whatever length is required to make it balance and to fit all the necessary parts inside. Mine is as short as it can be and have a conventional front end layout, with about a 6 1/2" space for the tank.

    Brett

Offline jim gilmore

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Re: Whats Eveyone Got Against Short Noses , ANYWAY .
« Reply #3 on: July 09, 2017, 07:32:59 PM »
i would not consider combat wings as stable.
i myself think nose length in real planes had more to do with fit and function.


Offline Matt Spencer

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Re: Whats Eveyone Got Against Short Noses , ANYWAY .
« Reply #4 on: July 09, 2017, 09:52:41 PM »
Quote
torque is torque, it doesn't matter where it is applied.

For every force theres an equal and opposite force , according to Pythagorus of hodini or somebody . If youll bear with me a miute .  :P

SO ; if we look at the EXTREMES , say the restraint was at a infinitely long , or infinitely short distance ( as in zero ) theyred be a differance
in MOMENT of Restraint ( to the tourgue reaction .)

At a guess , half the roll coulple is from the flying surfaces / aerodynamics . Half from restraint - as in lines and tip weight ( counter measure - at Times . At least an Inertial restraint .  >:( )

Then if we Define the Tourgue = Thered be the aerodynamic resultant due to the Revolving Propellor , The Translator or Transferer
of the rotational force . Being angled ( the blades ) the thrust is anoter resultant .

If THAT were a infinite distant Fwd or zero , its tracking around in holes and clumps in the atmosphere ( air ) would presumably be not the same leverage at either extreme .

Then theres drop off & acceleration .  >:( as when the loads off in a tail wind , or ' hole ' in the air . amongst other things , there less transferance from the prop .
and Conversly - Accleratng from there , if only relative to the atmosphere / air  - the Rotational Interaction is Stroger under heavy Load / Aceleration .

Assuming the Vert stab / Empenage are ' steering ' against this , and the wing restraining lateral rotation ; as weve said , at a guess 50 %
for the sake of a figure ,

one would assume say the prop distance to the C. G. / Aerodynamic Center would be of some relevance , due to ' p ' ,
 what Id call " Prop walk " -
where if say the load there is more about the bottom ( of the prop ) it tends to run to the right - like it was scuffing the deck - perhaps .

realise this is all rather non specific - but i think for visualising effects relevant , Then one 'd work out the relevant Maths Equations .  :o VD~




 
Quote
i would not consider combat wings as stable.

Flying one of Gibsons Cockroach Combat wings , with a Diesel in it , Fwd a tad , on 55 ft lines ; looks just like this :



Tho light on the lines and responsive to small handle movements , grooved superbly . Enough to recomend as a scedule ' learner '
economic masterpiece. Theyre called Cockroaches as theyre hard to kill , Mr Gibson related . ANYWAY , just saying . :-X

ANYWAY , regret I cant get further pictures on just now. New Ph Camera wont seem to load here direct .
All in silver apart from the new Fin , rubbed back , Layed out the rundels last night , underwing I D stripes earlier .
Primer over the ribs where sanded & ' gone thru ' corrected with balsa cement - primed ; it all looks good - or o.k.

Pre primer was a eyesoar at some places on the ribs. So mightilly releived there , So test flights may be in a week or two .
Fairly Convinced with the creeping weight / C. G. the next one / Tempest , will need to mould the Fuse - so means a Plug .
This ones largely by no means contest wood mostplaces . Hpe Camuflge wont weigh it down , after all the effort .
Maybe tryin get enough clear on to hold out the gloop , test fly - wash in meths 7 rub here'n ' there with acetone ,
then Camo ( Humbrol enamel sprayed ) and clear .

Out with the 320 to get the primer off , bar any hollows .

Offline Brett Buck

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Re: Whats Eveyone Got Against Short Noses , ANYWAY .
« Reply #5 on: July 10, 2017, 09:58:02 AM »
For every force theres an equal and opposite force , according to Pythagorus of hodini or somebody . If youll bear with me a miute .  :P

SO ; if we look at the EXTREMES , say the restraint was at a infinitely long , or infinitely short distance ( as in zero ) theyred be a differance
in MOMENT of Restraint ( to the tourgue reaction .)

At a guess , half the roll coulple is from the flying surfaces / aerodynamics . Half from restraint - as in lines and tip weight ( counter measure - at Times . At least an Inertial restraint .  >:( )

Then if we Define the Tourgue = Thered be the aerodynamic resultant due to the Revolving Propellor , The Translator or Transferer
of the rotational force . Being angled ( the blades ) the thrust is anoter resultant .

   The length of the nose would matter if the propellor applied a force to the nose. By definition, the gyroscopic precession is only a torque. The nose could be 20 feet long and the torque applied to the airplane as the result of precession would be the same. 

    The reason to have short noses is to reduce the moment of inertia, and the reason to make them any particular length is a tradeoff between the moment of inertia and the ability to balance the rest of the airplane without adding additional weight, and the necessary length to contain all the parts. Assuming the rest of the airplane aside from the nose requires a particular "balance moment" (i.e needs a fixed product of the CG and the mass of the nose to balance correctly), you will always have the lowest contribution to the moment of inertia by a short nose with a heavy weight as compared to a long nose with a light weight. But of course, the long nose with the light weight is lighter and has more space to put things.

      From a practical standpoint, you make the rest of the airplane however it needs to be for other considerations (primarily aerodynamic and structural). You have (or should have) a fixed mass for the parts in the nose since you have long since chosen a particular engine/tank/pipe system. Then you adjust it to try to balance without additional weight. If it all works out, you end up with a nose that is just long enough to contain the parts, which is the minimum product of inertia you can have for that situation, and the minimum weight that you could have and still carry everything.

    Brett
« Last Edit: July 11, 2017, 09:41:21 PM by Brett Buck »


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