Long Nose vs. Weight and Balance

Everyone is saying if you put the bigger engine on we need to lengthen our fuse 6in. can anyone produce sample weight and balance sheets that support this 6in vs 4in or 8.

 

Lynn

Split if you want I just post here cause it has the most people looking

Lynn

 

I worked up the W&B on my Long Ez, preliminary showed that I was full fuel and a 250lb GIB I was at the rear most Cof G envelope, using a 13b N/A with Tracys redrive. On landing I think it showed that I would be a bit nose heavy but not out of the envelope. I'll do a W&B chart again to see where I'm at. My buddy and I did this about a 1yr ago so my numbers may be off a bit I'll check. As far as the baggage strakes go I did not extend them forward with the longer fuse, I just planned on using wing pods. I think you can extend the strakes forward but I think you would have to change the leading edge angle

 

Tony

look at this and tell me if you think it will help me. It may just be for RC aircraft I dont know

http://adamone.rchomepage.com/cg_canard.htm

 

Lynn

Do you know how to calculate W&B for a Cessna or other traditional aircraft? If you're not yet a pilot, this is stuff that sinks in during ground school. If you don't have the TERF CD yet, there's a section on calculating W&B in the Long-EZ Owner's Manual that will be useful for considering this modification.

 

In simple terms, you need some extra leverage to balance the larger engine. Your nose could be 6" longer, or 40" longer. If you need to add extra balast to balance the engine so that the Cg is in the right spot, you need some place to put the balast. 4", 6", 8", or 40" are just guesses until you put each of your FINISHED plane's wheels on some scales to do the W&B proper. The Long-EZ Owner's Manual talks to this.

 

Forget the nose until you need to do it. By then you will have a better understanding of the variables at play.

 

Hope that helps.

Yes

 

all the numbers that I have are very preliminary just to kinda get me in the ball park. Once I get closer i'll put the wheels on the scales and see how good of a guesser I am

I am a pilot and have 150 hours c-172 time and alot of tamahawk time. I can easily do W&B on these aircraft. I also have the Long-ez and velocity W&B on a spreadsheet. What ive been trying to do so far is use the long-ez manual to try and get a new static empty weigh cg to plug into the spreadsheet. Doing this I have changed the stations rear of the pilot adding 6 inches to everything and guessing at what the weights might be with the bigger engine. I know doing it this way probably voids the W&B box in the manual since the overall CG will be aft a few inches. All I have done so far has not helped me. The numbers I plug in throw the cg 12 inches farther aft which sounds to me to far. I know the different engines weigh different and each aircraft should look to see if 6,3 or 8 inches is right for there bird. Im average weight and want to plan it with me as the starting point. I was just wondering where the 6inches came from. was it like the width borrowed from the berkut or did someone actually do the math.

Lynn

 

I worked up the W&B on my Long Ez,............... 250lb GIB I was at the rear most Cof G envelope, Tony

 

I thought I read here a 250 lb GIB? Just checking to see if it was a typo. I played Line backer for a semi pro team once and I weighed in at 235. That would throw any C of G, out of whack:scared:

If I understand correctly, the "electronically stitched" templates will eliminate the need to cut with scissors and tape together sheets of paper to get the full sized templates. When the templates are stitched together electronically, is there a set of original Long-Ez templates available that can be compared to verify these new "stitched" templates that we will print from PDF files at a place like Kinkos?

 

Also I'm not sure I understand the current status of the templates. I read and see from the attached pictures that the templates downloaded from thread #1 are "off" some but that this inaccuracy may have also been present in the original templates created by RAF. Has this been confirmed, that the current templates are the same as the Rutan originals? Are the current templates on thread #1 useable? Regarding the current templates in thread #1, is there a set of original templates available to which these current downloadable templates can be compared ? Maybe someone could give a description how the current templates were created. I have the TERF CD which was made by Mrs. Tait scanning documents from RAF making pdf files. There's no possibility for distortion or errors in that transition.

 

Sorry this is so long. If I'm going to build an airplane from these materials I just want to have confidence in these templates.

 

Thank you John Matcho for his time on this project and any others (dpaton) who have donated their time making the Open-Ez possible.

 

I'm not sure that Divine Providence is "onboard" for this project. I want to be in His grace and am well aware of the scripture, "Unless the Lord builds the airplane (house), he labors in vain that buildeth it." Psalm 127:1. The wife is ok with the idea of building an airplane and that's close to God!

 

This opportunity may be an answer to a prayer as I tried building a Wittman Tailwind, but there are no assembly, step by step, instructions for that airplane. After buying a fuselage and wings I read a quote from the late Steve Wittman, "a first time builder has no business building a Tailwind." Well I'm a first time builder so I sold the Tailwind.

 

 

 

Running across the Open-Ez project was great news. The TERF CD is very interesting.

 

Thanks,

 

Randy

CNCDOC

 

I'm sure it was a typo or more to the the point a memory lapso I can't find my sheet we did the w&b on I'm pretty sure it was 200 something? or another, because I'm 230lbs (full back) and I thought at some point I would find myself in the back

 

Randy

 

I think all of those questions could be answered best by Jon Matcho.

 

velocity dreamer

 

I didn't do the math initially when I stretched my fuse I just did what I was told I needed to do. My thought was I could move the batterys around to compensate for any ballast I might need. I don't know if that will work but I'm confident I can make it balance out at some point.

 

Tony

 

(why is that goat standing on a cloud)

Randy-

 

Since I'm the one doign the template stitching, I guess I'll answer here.

 

The template distortion is very real and very noticable, especially on the instrument panel, since it has a larger number of alignment points than any other template. The template files I'm working from have been compared to RAF originals, and the distortion is present in all checked versions. It's due to the way that copying technology worked back in the late 70s, before precision digital printing made its way into the mainstream. All template sets have distortion. As for the TERF CDs, there is some distortion in those, mainly in the scale of the drawings. If you print out the pagfes full-bleed onto legal paper, you'll see that the templates in the plans stack are slightly smaller than required. It's a fact of life...we're dealing with unlicensed and unblessed plans, and trying to build something new and better from them. There's lots of DIY involved.

 

The template status is...well...static. I've been swamped with work for the last few months, and I just haven't had much time to work on them. I'm hoping to get back into the swing of things this summer, and produce something real before the end of the year, but it's a volunteer effort and subject to the whims of my life. Tony has done a masterful job of documenting his various mods with CAD drawings, and in the mean time, his stuff might be a good educational tool.

 

I don't have original templates, but the ones that are remaining similar to the originals will be compared by someone with more access than I have. Some of them will be changing a lot, especially since the eventual 'final' version will include things like a longer nose, and perhaps a width adjustment and a length stretch, to help accomidate the larger/heavier engines (O-320, Mazda, Turbo Subie, etc) everyone seems to be using. Feel freee to continue this thread in the OpenEZ area...since that's where the discussion of the project really belongs

 

-dave

Everyone is saying if you put the bigger engine on we need to lengthen our fuse 6in. can anyone produce sample weight and balance sheets that support this 6in vs 4in or 8.

Well, yes and No;

 

Rather than add balast, I moved my battery forward approximately 12 inches from the original plans location. In order to do this, I had to extend the nose (I don't like the looks of the original nose anyway).

 

You could add ballast and leave the original nose.

 

I'v discovered that the GIB is so close to the CG that the GIBs weight has no impact on CG. HOWEVER, The pilots weight has a significant impact on CG.

 

If the W&B is set up for a heavy pilot (i.e. 250lbs) and then a light pilot flys the plane (i.e. 175 lbs) this could easily push the CG well past the aft limit.

 

Be very carefull

 

Waiter

Im back. Still thinking of every little thing I can think of and back on the subtect of weight and ballance I had another thought

 

By stretching the fus between the wing and canard, are we not changing the overall center of lift for the aircraft? And would this not change the aft end of our envelope? I understand the forword end is basicly a weight were we can not raise the nose to take off or flare. But the rear I think depends on the center of lift which once again I think we are changing.

 

Lynn

By stretching the fus between the wing and canard, are we not changing the overall center of lift for the aircraft?

Yes.

And would this not change the aft end of our envelope?

Yes.

 

Which is why stretching a canard aircraft is not to be taken lightly.

thanks Marc for the quick reply.

I was hoping one of the aeronotical engineers on the site could shed some light. I personally do not plan on widening my fuse or do I need it longer except to put a larger engine. right now im figuring exactly how much ballast I would need if I didnt make it longer.

 

Lynn

Weight and balance is just simply getting the teeter-totter to do its thing. The big thing is to get the right moments that get you within the CG box. The moment is the weight times the distance from whichever datum you are using.

 

As an example, you have heard people saying that you could either move a battery forward by building a longer nose---or you could add ballast to an existing nose. For some reason, that seems to confuse some people---but:

moving a 20lb weight forward 12 inches (20x12=240inlb)

is the same as

moving a 12lb weight forward 20 inches (12x20=still 240inlb)

 

So...what people are trying to do with the longer noses, is to use longer distance so they can use lighter weight. If I have a real teeter-totter with a 200 lb person on one seat, I will need a 200 lb person on the other seat for it to balance. If I thought of the teeter totter as an airplane, I might not want to use all that weight. So how do I balance the 200 lb person on the teeter-totter with only a 100 lb person? One option (but 3 solutions to get there): leg with 100 lb person needs to be twice as long as the one with the 200 lb person

-build extension on 100lb leg that is twice as long as the other

-cut leg in half on 200 lb leg

-move fulcrum until 100lb side is twice as long as 200 lb side

 

When you do CG calculations, all you are doing is figuring out where that fulcrum is. You make all your calculations based on the same station. It would be cool if you did calculations right from the fulcrum---but that is what you are trying to find---so you usually just pick a place to measure from.

 

Quick example with my teeter totter.

Given:

-30 ft long teeter-totter

-200 lb man on one side

-100 lb man on the other

 

Where is the CG?

 

Picture:

200 lb man----------------------------------100 lb man

 

lets measure from the left (but we could pick from anywhere (including an imaginary line off the teeter-totter)

W/B=sum of moments/total weight

 

W/B=((200lb x 0 ft)+(100lb x 30 ft))/(200lb + 100lb)=10ft(as measured from the left--which is where we started)

 

Does this make sense?

On the one side 200lb x 10ft=2000 ftlbs

On the other side 100lb x (30-10ft)=2000 ftlbs

So what we have done is to put the fulcrum 10 ft from the left side---and it will balance.

 

Through experimentation, you could find that you can move the fulcrum left and right by a certain amount--and still have a good game with the 100 and 200 lb man. But if you move it too much, then you won't be able to play the game----one side would be permanantly on the ground. This is essense would be the CG box

 

Back to aircraft. You know where you want the CG to be. You know where all the parts are---you just have to put them in a spreadsheet and add them up. You have a sample sheet with a O235 on it and want to put a O320. You have the sample calcs of the whole aircraft---but it does not specify the engine because the engine was measured with the aircraft. But no big deal----you know the station where all measurements are being done from----just subtract out the O235. Look up the engines approx weight with the accessories that are on it. Look at what station the engine is on---use the drawings. Subtract out the moment. Then add the O320 in using the same techniques.

thanks Marc for the quick reply.

I was hoping one of the aeronotical engineers on the site could shed some light. I personally do not plan on widening my fuse or do I need it longer except to put a larger engine. right now im figuring exactly how much ballast I would need if I didnt make it longer.

 

Lynn

The other thing you need to think about, should you make it longer, is, will the added weight of the structure that you are adding equal or exceed the additional weight that you must add (for your desired w/b) with the standard length nose.

 

If it is a wash, or even slightly less, you will be doing a lot of work for nothing.

 

You could always go on a reverse diet!

Back to aircraft. You know where you want the CG to be. You know where all the parts are---you just have to put them in a spreadsheet and add them up. You have a sample sheet with a O235 on it and want to put a O320. You have the sample calcs of the whole aircraft---but it does not specify the engine because the engine was measured with the aircraft. But no big deal----you know the station where all measurements are being done from----just subtract out the O235. Look up the engines approx weight with the accessories that are on it. Look at what station the engine is on---use the drawings. Subtract out the moment. Then add the O320 in using the same techniques.

This will work. I think you can even make it simpler. Find the station for the engine put it on the W & B sheet and put in the "difference" between the new engine and the old. It will be the same as if you added a starter after the original calculations. The engine station should be somewhere near 140-145 but verify this.

Yes, there are a bunch of different ways to skin the cat. However, if you start at the beginning of the thread, I think that there are some out there that do not really know how to do a W/B. I am pretty sure that everyone who has posted can take a W/B chart from the POH (LEZ, Cessna, etc) and work it---but not sure that everyone could calculate a modification like add more instrumentation or adding on a lightweight starter, etc.

 

It is more than just calculations---it is understanding the fundamentals.

I understand how to do weight and balance and change it for adding equipment. However what I am getting at is!! Doing the W&B on a cherokee 140 and the W&B on a tamahawk are vertually the same except the moments and the CG Box. Why is The CG Box different? its a different aircraft. When stretching the Long or Open EZ between the canard and the wing you are virtualy making a different aircraft. Your not just changing the shape(like changing the nose) but the the overall aerodynamic stability. Shure you can remeasure everything and come up with a New Static CG and do a W&B, But You can not use the Old CG BOX. I can make a Tamahawk balance whin the CG box of a Cherokee 140, But that would not be safe. When I started this thread My question then and still now. How do you Determin the New CG Box

 

Lynn

I think what everyone is trying to tell you is that you don't change the CG box

That dangerous unless your an aero engineer.

 

The wing/canard relationship does not change or should not change by adding a bigger engine. To keep things in the box, the added weight is offset by either adding weight to the front or shift the weight up front. The most popular convention has been to make the nose longer so the battery weight

can bemoved further forward.. The canard position does not change,the nosewheel stuff does not change and the wing does not change.

 

It's the easiest solution.

 

Go past this and I think you have to start playing with the relationship between cg and center of lift.

 

I am a heavy pilot. I could put the bigger engine in and probably not have to change anything to stay in the box.

I second what RGlos says. Stretching the nose on a Longez or making the engine mount longer/shorter or adding weight here or there does not change the CG box. If you change the wing/canard relation or remove the lower winglets, or change the length of the canard...the only way to determine the CG box is to flight test it (well---I'm sure that it can be calculated (I don't know how to do it)---but can only really be determined by flight test).

 

Nat Puffer used a test pilot and had a large tubular mechanism that went from the nose to the back seat. It had a big weight in it that could slide back and forth. Finding the aft CG involved getting the Cozy into a main wing stall which is not good for a canard aircraft. However, the sliding weight would could get the aircraft back into its box for safe flying. The Cozy did not originally have lower winglets. When Nat was not getting the aft CG he was looking for, he put the lower winglets back on---and regained some of his aft CG----but still not good enough. He then cut several inches off the canard---got some more aft CG back but still not enough. Cut off some more---and finally satisified. He may have even gone back and cut some more for margin---but can't remember.

Lengthening the nose does not, on its own, change the CG. But it DOES create the opportunity to use less weight to get the aircraft back into the box. One pound of that's 5 feet forward has a bigger effect than the same weight 4 feet forward.

 

So the lengthened nose as a C/G modifier has to come with a plan for making use the the increased movement/arm.

When stretching the Long or Open EZ between the canard and the wing you are virtualy making a different aircraft. Your not just changing the shape(like changing the nose) but the the overall aerodynamic stability. Shure you can remeasure everything and come up with a New Static CG and do a W&B, But You can not use the Old CG BOX. How do you Determin the New CG Box

 

Lynn

Lynn, you are correct. There are two sub threads going on here. When one simply lengthens the nose of a Long-EZ and moves weight forward to balance the bigger engine, you can use the original CG box.

 

When lengthening the cockpit area, there are two ways of doing it. 1) moving the front seat back and canard bulkhead forward which changes the distance between the MAC of the canard and the main wing. 2) moving the front seat bulkhead forward while leaving the canard bulkhead in its relative postion to the main wing. If you choose option 1, you will need a new CG Box. Like you said, if you change the distance between the main wing and the canard, you have a new design and you require a new cg box. Maybe the Berkut drivers can chime in here as they probably have a different CG box from a Long-EZ.

 

How to determing a new CG box after changing the design (or making a new one)? It takes someone a lot smarter than me to figure it out. Hollman's book is pretty good. I can follow it (so most anybody ought to be able to).

 

Maybe some of the aerodynamic experts on board can help us out here.