fixed gear vs. retracts

[Rcmaster199 at aol.com]

The composite fixed gear designs of today are quite the overkill in terms of 
strength, rigidity and weight. They could be made far lighter, less rigid and 
cheaply enough where, as they break on a hard landing, simply pull the pieces 
out and toss them. 

My good friend Nat Penton is using regular carbon tubing material for the 
struts, and uses a short piece of aluminum rod epoxied in the tube, to serve as 
wheel axle. A quick wrapping of kevlar thread, super glued on the carbon tube 
where the axle in epoxied, keeps the tube intact.

He is reporting that the struts weigh in at less than 1 oz for both, with the 
farings installed to a fully airfoiled section, without the wheels. The 
length is 10 inches.

Matt

PS- I prefer retracts to fixed gear for pattern planes except they are too 
heavyat around 6 ozs sans wheels. 

My composite gear that I make, come in at about 4 ozs with pants, for the 
pair, sans wheels, but will be using Nat's technique to reduce the weight further 
with little compromise in strength. I'll probably write about it for the KF. 
If you have been following my writings you should have learned that I have 
been keeping no secrets.



> Subj:Re: fixed gear vs. retracts 
> Date:7/16/2003 12:31:38 PM Eastern Daylight Time
> From:<A HREF="mailto:tkeithb at comcast.net">tkeithb at comcast.net</A>
> Reply-to:<A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> To:<A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A>
> Sent from the Internet 
> 
> 
> 
> It wasn't that long ago that I was asking the same question on this list. I 
> ended up going with retracts for three reasons. 1) Less bounce on landings, 
> 2) Transportation and storage (no gear sticking out from fuse), and 3) 
> Landings in the weeds are less likely to tear something up. All of these are major 
> considerations for me.
>  
> Now I'm building my second 2M plane and I've decided to go with fixed gear 
> for the following reasons. 1) Putting the plane together and taking it apart 
> at the field is faster, no need to mess with hooking up the retract servo. 2) 
> You can set the fuse on the ground and slap the wings on right by the car, no 
> need to use a cradle as with retracts. 3) No need for constant 
> inspection/tweaking with the struts. Even with smooth landings I periodically have to bend 
> the struts back forward and I feel compelled to check them after each flight 
> to avoid having them jam and draining the battery the next time I fly. 4) 
> Makes the wings much easier to build. 5) When flying in poor light conditions, 
> like when the plane is silhouetted by the sun, the gear sticking out gives 
> another reference point to confirm orientation. This can be helpful when doing 
> rolls, etc. and all you can see is a shadow. 6) With fixed gear you can taxi 
> onto the runway and not carry the plane out each time.
>  
> Both approaches have their definite advantages. My main reservations with 
> changing to fixed gear are damaging the fuse from deadsticking landings in high 
> grass and scoring downgrades due to bounced landings. Hopefully these won't 
> be a big issue. I'm looking forward to my fixed gear plane!
>  
> Keith Black  
>  
> 
> >> ----- Original Message ----- 
>> From: <A HREF="mailto:wgalligan at goodsonacura.com">Wayne Galligan</A> 
>> To: <A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A> 
>> Sent: Wednesday, July 16, 2003 10:13 AM
>> Subject: fixed gear vs. retracts
>> 
>> 
>>    How light is light on the 7075 aluminum l.g. setup?   My setup with 
>> Bolly F3A large gear with wheel pants, axles and wheels weights 7.5 oz    I fly 
>> off grass and have had no problems with the setup where guys with retracts 
>> are constantly fiddleing and tweaking the struts.  The big plus(for me) is 
>> set-up.   Easier to build light wings, no linkages, one less servo, sets up in 
>> the field in no time flat.   As for tearing it up on hard landing.... just 
>> dont land in the tundra.  That is a plus for retracts if you have the gear 
>> up, otherwise retracts can tearup a good set of wings if stuck down or if one 
>> hangs up or colapses on landing on the runway.  Its a fliers choice.  I 
>> have fixed gear on 3 airplanes now and lovem all.  
>> I personally like the looks of a nicely setup fixed gear airplane.   
>>  
>> Wayne G
>> 
>> >>> ----- Original Message ----- 
>>> From: <A HREF="mailto:johnferrell at earthlink.net">John Ferrell</A> 
>>> To: <A HREF="mailto:discussion at nsrca.org">discussion at nsrca.org</A> 
>>> Sent: Wednesday, July 16, 2003 8:50 AM
>>> Subject: Re: Nats photos online
>>> 
>>> 
>>> From this site and personal experience:
>>>  
>>> The change to fixed gear on the Prophecy seemed to require less power than 
>>> those with retracts. 
>>>  
>>> It seems to me that the weight is about the same.
>>>  
>>> A harsh landing with retracts usually results in needing a little 
>>> attention on the struts.
>>> The same landing with fixed gear frequently results in extensive damage to 
>>> the fuselage.
>>>  
>>> There is less bounce with retracts.
>>> Taxii out is not recomended with retracts.
>>>  
>>> Retracts usually provide a wider footprint .
>>>  
>>> The wire gear in the pictures on Pastorello's web site looks a little 
>>> heavy but should be less punishing to the airframe than the fixed aluminum or 
>>> composite gear.
>>> 7075 Aluminum gear is lighter and more durable than any of the composite 
>>> gear. Unfortunately, it is harder to work and not nearly as available as 
>>> 6061.
>>> 6061 aluminum for fixed gear is a waste of time.
>>>  
>>> If landings were all scored K4, stif gear would go away...
>>>  
>>> John Ferrell 
>>> 
>> 
>> 
> 

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