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A lighter 701
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Benjamin Q

Joined: 04 Mar 2009
Posts: 13
Location: Twentynine Palms, CA

Posted: Tue Sep 14, 2010 9:54 pm Post subject: A lighter 701

My work on my 701 was unexpected stalled by a surprise deployment to Afghanistan.  I am an engineer, so I have spent quiet a bit of free time thinking about the 701.

  Two things really impress me about the 701...it's lightweight and it's modular design.  As lightweight as it is, it seems like there are areas where you could take advatage of its modular construction and use carbon fiber to save a few pounds.  Some of the steel pieces like the rudder pedals could be replaced.  If you accounted for the COG shift you might be able to fabricate all the tail section pieces and flaperons out of carbon fiber.  And if you did some honest-to-goodness engineering, you could switch out the landing gear and make some aerodynamic struts.

  When I get home I might weight the parts and pieces and do some back of the envelope calculations and see what kind of weight savings a person could expect.

  Has anyone else looked into this?  I've already finished all the major modules of the kit, but it seems like it would be an interesting way to continue to the build/experimentation phase after the airplane is done.

   I would be interested to hear your thoughts.

klondike(at)megalink.net
Guest

Posted: Wed Sep 15, 2010 5:53 am Post subject: A lighter 701

my opinion only-----  don't waste to much time reinventing the wheel.

get your airplane in the air asap and after you are enjoying the GREAT 701

make your mod(s) afterwards------------  after flying this thing, the things 

you

mention below will not seem so important.



Fritz  do not archive

---

john.marzulli(at)gmail.co
Guest

Posted: Wed Sep 15, 2010 6:13 am Post subject: A lighter 701

Mark Townsend / Can-Zac were offering streamlined, one piece struts make out of aluminum.



John Marzulli



http://www.GenevieveMarzulli.org/

http://MarzulliPhoto.net/

 http://701Builder.blogspot.com/

 



On Wed, Sep 15, 2010 at 6:51 AM, fritz <klondike(at)megalink.net (klondike(at)megalink.net)> wrote:

[quote] --> Zenith701801-List message posted by: "fritz" <klondike(at)megalink.net (klondike(at)megalink.net)>

 

 my opinion only-----  don't waste to much time reinventing the wheel.

 get your airplane in the air asap and after you are enjoying the GREAT 701

 make your mod(s) afterwards------------  after flying this thing, the things you

 mention below will not seem so important.

 

 Fritz  do not archive

 

 

 ---

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Wed Sep 15, 2010 7:31 am Post subject: A lighter 701

They are nice but heavier than the thin  (.035) 4130 tube with .016 covers.  figured it up a long time ago  and I think I remember 4-5# but I'd have to do it again to be  sure.

  

 John

 [quote]   ---

Curt Thompson

Joined: 09 Jan 2009
Posts: 18
Location: Redmond, WA, USA

Posted: Wed Sep 15, 2010 8:51 am Post subject: A lighter 701

I made a fiberglass mold and built a carbon fiber fairing for my horizontal

stab (picture attached).  I'm having second thoughts now because I have been

looking into the issue with galvanic corrosion between carbon fiber and

aluminum.  It looks like I would have to electrically insulate the part from

the aluminum.  I'm not sure how I'm going to do that.  I might just make

another part out of fiberglass.



Curt

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John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Wed Sep 15, 2010 9:43 am Post subject: A lighter 701

Something as simple as a layer of electrical tape would most likely suffice, 

you only have the problem when moisture is present (all the time around my 

house)

The resin also encapsulates the carbon fibers and isolates them from the 

aluminum.Maybe a thin strip of veil mat around the perimeter where it 

touches .  Have used this method in Houston several times with success, 

YNMV.



LO&SLO  John



---

Curt Thompson

Joined: 09 Jan 2009
Posts: 18
Location: Redmond, WA, USA

Posted: Wed Sep 15, 2010 11:03 am Post subject: A lighter 701

John,



I was more concerned about attaching it with rivets.  I doubt if I can

insulate around them.  I thought about using nylon machine screws but I

would have to put in a bunch of anchor nuts.



BTW, that picture is of the first part I made.  The second part looks a lot

better, without surface voids, and better penetration.  It really helps to

have a second set of hands while trying to lay this stuff up.



Curt



--

Benjamin Q

Joined: 04 Mar 2009
Posts: 13
Location: Twentynine Palms, CA

Posted: Wed Sep 15, 2010 5:09 pm Post subject: Re: A lighter 701

Fritz, I do intend to finish the airplane first.  I feel like I making great time.  I finished most the airplane in less then 6 months.  I still have to finish the controls, and put all the major modules together and finish the whole FWF.  Once that it is all done, this would be an interesting area to tinker.

John, I looked into those, and I wasn't real happy with the weight penalty. I think I would just make some light aluminum fairings for the current struts before if I were going to stick to metal.  The main point of the carbon fiber struts would be the weight savings, but after you made the rounded core, you could make a light aerodynamic skin.

Curt, I have been looking into the galvanic corrosion issue.  I was talking to one of the other engineers I work with who has worked with carbon fiber before.  Specifically, we build a carbonfiber boat hull that had some aluminum pieces, like the rudder.  The boat was tested in the ocean (salt water) for a few years.  They took some simple precautions in during the design and fabrication phase and took special notice of any corrosive effects.  After a few years of testing they didn't see any irregular or accelerated corrosion patterns.

I like the idea of performance through efficiency rather then performance through raw power.  I don't intend on painting the airplane, and I plan on using the Jabiru 2200 engine setup.  The lighter the plane gets, there is a bigger the proportional impact made from any weight changes.  It seems that lightening the airplane might have a realistic benefit.

By the way, what kind of weights are you all seeing with your individual setups?  The website says 580 lbs, but I assume that is with a 912S and minimal instruments.  I think I read somewhere that the paint alone can weight 30 lbs.

dougsnash

Joined: 14 Apr 2008
Posts: 281

Posted: Wed Sep 15, 2010 7:25 pm Post subject: A lighter 701

I'm almost embarrassed to say my 701 weighs 667 empty.  That is with a bed style mounted 912UL, slats and full paint.



Some areas where I let the weight get away from me are as follows:



020 wing skins on top bottom and leading edge

leather covered temperfoam seat cushions.  I weighed one seat bottom and it was over 5 lbs.

The interior of all aluminum surfaces were primed.  This is required in Canada.

Electric flapperons, the actuator is heavier than the manual control.

Fairly complex electrical system. including a transponder and comm radio, full lights etc.



Let that be a warning to those of you still building, little additional weights add up to big ones.



Do Not Achive



Doug MacDonald

CH-701 Scratch builder

NW Ontario, Canada



--- On Wed, 9/15/10, Benjamin Q <ben.queener(at)gmail.com> wrote:



 	  Quote: 	
		   From: Benjamin Q <ben.queener(at)gmail.com>

 Subject: Re: A lighter 701

 To: zenith701801-list(at)matronics.com

 Received: Wednesday, September 15, 2010, 8:09 PM

 --> Zenith701801-List message

 posted by: "Benjamin Q" <ben.queener(at)gmail.com>


	


 	  Quote: 	
		   By the way, what kind of weights are you all seeing with

 your individual setups?  The website says 580 lbs, but

 I assume that is with a 912S and minimal instruments. 

 I think I read somewhere that the paint alone can weight 30

 lbs.

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Fri Sep 17, 2010 1:00 pm Post subject: Re: A lighter 701

I had wondered why you guys did that. 



Kevin

do not archive



 	  dougsnash wrote: 	
		  

The interior of all aluminum surfaces were primed.  This is required in Canada.



Doug MacDonald

CH-701 Scratch builder

NW Ontario, Canada



--- On Wed, 9/15/10, Benjamin Q <ben> wrote:



 	  Quote: 	
		   From: Benjamin Q <ben>

 Subject: Re: A lighter 701

 To: zenith701801-list(at)matronics.com

 Received: Wednesday, September 15, 2010, 8:09 PM

 --> Zenith701801-List message

 posted by: "Benjamin Q" <ben>



	


 	  Quote: 	
		   By the way, what kind of weights are you all seeing with

 your individual setups?ï¿½ The website says 580 lbs, but

 I assume that is with a 912S and minimal instruments.ï¿½

 I think I read somewhere that the paint alone can weight 30

 lbs.

_________________
â€œAlways do what you are afraid to do.â€
R.W. Emerson (1803-1882)

"Real freedom is the sustained act of being an individual." WW - 2009

"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune

raymondj(at)frontiernet.n
Guest

Posted: Fri Sep 17, 2010 2:08 pm Post subject: A lighter 701

Benjamin,



	I understand your desire to continue to experiment after the airplane 

is complete. I think considering the options, even if you never 

implement any of them, is a good way to fill extra time you may have and 

to keep construction/creative juices flowing.  Every ounce you can save 

has benefits. And it IS called experimental aviation.  Of course one big 

question is always the cost/time/benefit relationship.



For more specific thoughts I would look at experimenting with things 

that could be more easily changed. I saw one somewhere that had a carbon 

fiber instrument panel.  I am looking at maybe using composites on my 

750 for the seat pans, control sticks, pedals, muffler bearings, and who 

knows what else.



Every design is a collection of compromises, maybe you can find a set 

that suits you better than the designer's original.

Raymond Julian

Kettle River, MN



On 09/15/2010 12:55 AM, Benjamin Q wrote:

 	  Quote: 	
		   



 My work on my 701 was unexpected stalled by a surprise deployment to Afghanistan.  I am an engineer, so I have spent quiet a bit of free time thinking about the 701.

    Two things really impress me about the 701...it's lightweight and it's modular design.  As lightweight as it is, it seems like there are areas where you could take advatage of its modular construction and use carbon fiber to save a few pounds.  Some of the steel pieces like the rudder pedals could be replaced.  If you accounted for the COG shift you might be able to fabricate all the tail section pieces and flaperons out of carbon fiber.  And if you did some honest-to-goodness engineering, you could switch out the landing gear and make some aerodynamic struts.

    When I get home I might weight the parts and pieces and do some back of the envelope calculations and see what kind of weight savings a person could expect.

    Has anyone else looked into this?  I've already finished all the major modules of the kit, but it seems like it would be an interesting way to continue to the build/experimentation phase after the airplane is done.

     I would be interested to hear your thoughts.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=312491#312491

Benjamin Q

Joined: 04 Mar 2009
Posts: 13
Location: Twentynine Palms, CA

Posted: Fri Sep 17, 2010 5:30 pm Post subject: Re: A lighter 701

I love to fly and getting in the air is my first priority.   But one of the reasons I settled on the 701 kit was because it hold a very distinct plane in the experimental aircraft world as a STOL aircraft.  I think its exciting to already be at the edges of STOL performance and still be able to make a meaningful design contribution.  I wonder if it is possible to bring the 701 to under 500 lbs?

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Sat Sep 18, 2010 2:35 am Post subject: Re: A lighter 701

How about 460 lbs

But you need a set of early plans and a 2 stroke engine, well maybe a Jab 2200.

Click it

http://web.archive.org/web/20010422100422/www.zenair.com/stolch701/7-perf.html



Kevin

klondike(at)megalink.net
Guest

Posted: Sat Sep 18, 2010 4:01 am Post subject: A lighter 701

I think you'll find Chris'  "first" model of the 701 was about 480 lbs.  To 

do this was with the "light weight" 2 cycle Rotax engines  ie 582.   Much 

lighter landing gear and lighter contstruction.   This 701 was "beefed up" 

for the heavier and more hp engines.

 Just build the damn thing and have fun flying it.

Fritz ---- do not archive

---

arno7452(at)bellsouth.net
Guest

Posted: Sat Sep 18, 2010 7:56 am Post subject: A lighter 701

This should be no problem.  Mine came in at 600 lbs without trying to 

reduce.  Following are suggestions:

- no radios

- minimum instruments

- 50 lb engine

- smaller wheels and tires

- no lights

- no starter

- no alternator

- no doors



That would bring it in at about 490 lbs.

Regards,

Ken



do not archive



---

klondike(at)megalink.net
Guest

Posted: Sat Sep 18, 2010 9:26 am Post subject: A lighter 701

if you reduce the hp to weigh less.

what is the point?

Fritz--- do not archive

---

larry(at)macsmachine.com
Guest

Posted: Sat Sep 18, 2010 10:25 am Post subject: A lighter 701

Hi Fritz,

You'd find that a lighter aircraft actually performs better, even with the

smaller engine. There's a  much higher proportionate penalty for using

the larger engine. Fuel usage isn't much the problem as actual flying

performance for landing, takeoff and handling in the air.



Larry McFarland  601HDS at macsmachine.com



--

klondike(at)megalink.net
Guest

Posted: Sat Sep 18, 2010 11:24 am Post subject: A lighter 701

Larry --- I disagree---  not that straight forward of an answer.



you can't take a new 701,  put the Rotax 582 and expect good performance. 

You would need the old, lighter 701 for it to balance out.   No more than 

you can put a 65 hp in the 750 and expect good performance.



Don't want to start a major discussion on this, as I think we are all in the 

same church, but maybe different pews.



Fritz ---- do not archive



---

larry(at)macsmachine.com
Guest

Posted: Sat Sep 18, 2010 1:24 pm Post subject: A lighter 701

You're right of course, but I should have said not 2-cycle engines, but the

2200 Rotax is a great light engine for the 701 as compared to 

the 912.  It's light and offers great flying in a 701.  I've seen a lot of

other heavy engines like Corvair and Subaru which make the 701 a 

virtual led sled for climb and landing. 



Larry,



--

Benjamin Q

Joined: 04 Mar 2009
Posts: 13
Location: Twentynine Palms, CA

Posted: Sat Sep 18, 2010 8:17 pm Post subject: Re: A lighter 701

I plan on using the Jabiru 2200.  I can't remember how much lighter its installed weight is then the Rotax 912, I think it was 20 to 25 pounds.  I was going with minimal radios and instruments and no paint.  I would need to weight some of the parts to make sure, but I think I could shave off 40 to 50 pounds by making composite parts.  I also have some seat designs that will be super lightweight.  If keeping the paint off subtracts another 30 pounds, then it seems to be very possible to break 500 lbs.

The interesting thing about that web link is the performance numbers. They list the climb rate of the 80 HP 701 as 1600 ft, and the takeoff roll as 45 feet.  I have a feeling this was optimistic, but if not, it shows an incredible performance increase by just decreasing the weight.

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