Lynn Erickson

I have version 3 of the plans, and micro slurry is not described as peanut butter texture.

I would say then follow the plans. what I should have said is what you were told is not correct for LOW-VAC, or any composite parts being made in this century, the plans method, I am sure did not talk about LOW- VAC. the discussion here is about low vac and weight, which is a mod to the plans and many that have used that method do not pore on their micro, they use it more like peanut butter.

Well, that sure as heck isn't what Burt and Mike demonstrate in their video...and what is described in the plans, chapter 3.

 

The micro slurry is RUNNY - more like molasses than peanut butter. The thicker stuff is called dry micro, and is used to fill holes, dings and areas such as the trailing edge over the peel-ply.

 

My completed center spar weighs 44 lbs - that seems comparable to other builders who have a reputation for excellent construction technique.

 

I'm working on my wings now, and if I tried to spread dry micro on the wing, I'm sure I would damage it because of the hollow portions and the need to press hard with the squeegee to move dry micro around.

 

Mike Melville's demonstration in the video shows him POURING the micro slurry on the foam, moving it around with light passes of the squeegee, then using firmer strokes to remove most of it. Then he lays down the glass cloth, pours on pure epoxy, moves it around the part until it is wet out, then squeegees off the excess.

 

I sure hope I'm doing this right! I had a couple of inspectors check my work a couple of weeks ago and got a "thumbs up" from them. They are both A&P's and one does fiberglass work for the airlines as his day job.

how long ago was that video made. now a days we have peanut butter that will spread on the bread without tearing it. micro is light , resin is heavy, buy adding the most micro possible and still being able to apply the stuff on a given surface the lighter the part.

A fellow builder asked me, and I just got a phone quote for chroming the valve covers for 38.00 each and the same per pushrod tube. Can the pushrod tubes be simply buffed out to a chrome-like appearance? Inquiring minds want to know....

I would say that is cheap for the speed gain you will get. most every thing in aviation cost about $1000 for every 1 Knot increase in speed. everyone knows that if it is chrome it will go faster.

I went to one of the original glassing forums at Oshkosh in the mid 80's.

 

The stipling/squegee technique was developed to get the lowest weight possible.

 

1) Spread the micro on the foam.

2) Stipple the glass into the micro

3) Scrape off the excess with the squeege

 

The amount of epoxy was only enough to fill the glass. After repeated squeegeing, I found the proper blend of micro/epoxy to make the technique consistant. This left the glass with almost a dry look. I would not have learned this easily without the forum. I knew what to look for.

 

It is now 30 years later. How does this knowledge get down to new builders.

 

Vacuum bagging. I guess that replaces number 2 above. But if you don't know know what how much to do #3 or if the micro is too wet in #1 where does that leave you. It leaves you with a 950+ lbs Long EZ or 1300 lb Cozy MK IV. even with the vacuum bagging and you won't know how badly you've done it until you put it on the scales for the first time.

 

I guess what I'm saying is that don't count on Bagging alone to save weight. You must insure that you have amply used the squeege.

 

Idealy, find one of the original builders to pass his knowledge along.

if that is what they told you it is not correct. you do not want to stipple the glass and pull up the resin with the micro in it. you do not want the micro to get into the glass. the micro should be put on as dry as possible (peanut butter) it should not be runny at all ( runny is heavy ). the dry micro is to fill the foam pores with a lightweight compound of the resin so it will stick to the foam but not weigh as much as pure resin. when the micro is mixed correctly there is not any extra resin in it to stipple up into the glass. the glass should be wet out with resin from the top . this keeps the micro in the foam and from coming up into the glass. squeegeeing is to remove any air and get off the excess resin. micro in the glass weakens the layup. it is the same as air in the layup. this is another reason to hard shell before vacuum bagging, the micro in the foam can not be pulled up into the glass layup. vacuum bagging compresses the glass to a smaller volume so it can't hold as much volume of resin but does leave the weave filled with pure resin. On thin layups like 2 or 3 plys it does not really save any weight. what you gain by compressing the fibers is lost buy filling the weave with heavy pure resin instead of a light weight filler. when used on the uni that is used on our canards it will add weight.

 

 

I'll be very anxious to see how these changes actually affect the flight characteristics of this bird.

it will feel heavier, longer take off, slower roll but pitch sensitivity will be about the same. you can feel even 20 lbs. increase.

Is the airfoil on the MKIV canard and wing different from the Long EZ?

Is the span length different? What about elevator shape and ailerons?

the airfoil is the same. the cozy IV wing is 12" longer in span per wing. all added on the inboard section. from the outboard end of the strake to the wing tip is the same. ailerons are the same. if you compare the roncz canard on the cozy IV and the long ez the exposed canard and elevator lengths were the same until NAT made a change to the cozy IV canard by cutting off some length. most who cut off some canard length had to increase the angle of incidence. there are cozy IV's with both length canards out there.

PIRP;

 

 

 

My biggest surprise was the weight. 1170 lbs (OUCH). I'm about 1/2 inch aft of limit, so may need to add ballast in the nose.

 

My original weight was 950 (Great American prop, fixed gear)

 

I was looking at about 1050 - 1075, so I'm about 100lbs heavier than I thought.

 

Waiter

thats a bunch, what did you put in there. the gear should add an extra 75 lbs. and the prop about 35 lbs. where did the extra 100 lbs come from. some in the big tires and brakes. but the are no wheel pants. some in the wheel fairings. go thing is it does not hold as much fuel as it did?

I am curious why would down draft cooling give you any more than updraft cooling?? My Longeze had armpit scoops just like the ones you have on the top. What is the difference?? Steve

with up draft cooling the cold air is heated by the exhaust pipes before it goes up through the cylinders and it also comes in contact with more of the hot engine case/ oil pan before the cylinders.

Talk to JD at Infinity Aerospace.

He's the only one I know of that works with custom, oleo applications in the homebuilt/experimental market .

if you want to order them and pay for them then go to Infinity. if you want to receive them in ones life time it has not been a good place to go. TMann, you know I have to make sure everyone has both sides to the story. in fact you are still waiting aren't you? how long has it been now ? or did you get a old second hand set just in case?

Is there any hard data on whether or not using the low-vac technique produces truly lighter parts when combined with the moldless foam core process on the EZ family?

to answer the question. no there is no hard data. for there to be hard data to prove that, it would have to be true. I believe it is not. I have seen some parts made that way that are heavier. in general there is not much difference in weight but it is more complicated to do, requires more expense, and is a very wasteful process. All the extra materials used for the process end up in a land fill.

> most of the aircraft built are not post cured.

 

Maybe the homebuilt canard variety isn't. Every commercially built composite airplane most certainly is post-cured.

 

 

I was referring to our canard aircraft and that is a pretty bold statement that you know that they all are most certianly post cured. should I start naming the ones that I know are not. there are plenty of commercially built aircraft parts that are hand layups and are not post cured.

Not being an expert on composites, I have listened to many discussions. This post curing of composites in the sun seems to "fly" in the face of other things that I have heard about UV deterioration of epoxy structures.

 

Do you put sunscreen on the unfinished components prior to placing them in the direct sunlight? Or maybe; is this limited time in the direct sunlight not enough to be concerned about?

most of the aircraft built are not post cured. I believe Burt stopped recommending it very early in the program.

ColinB

 

Here is a Reality Check you should look at:

 

http://members.iquest.net/~aca/index.htm

 

Nice work, which he displayed last year at Oshkosh.

 

But it has taken him Y-E-A-R-S to get this far along.

 

And the Corvette Engine it is based upon may now

vanish under the new "Government Motors"...........

 

Then look at www.wingco.com..........

 

JP

I like the way he says he will work all the bugs out before he sells any parts, yet he is offering the kit for sale even before it has flown. building his own prop is a waste of effort if he ever plans to finish. where do we sign up for the test pilot seat? New airframe design, retracts, carbon gear box, his own prop and auto engine conversion all done in one test bed, all built by a guy that has no aircraft experience. just because a guy can make pretty carbon parts does not mean it will fly.

 

and the wingco it had one major flaw, it could almost fly

actually the center spa is the first thing that will be built via autoclave

 

 

also yes you are correct about your foams not being upto clave temps if you read back to some of my posts i explained i will be using a different foam (rohacell) with the same density as the one you use

before you can build a spar separate from the wing you will need dimensions and the plans do not have dimensions for the spar directly. you may be able to derive at the dimensions by doing a full size layout. by the time you do all that you could have cut out the wing foam and had it glassed. also the wing templates are not lined up with the butt lines directly so there will be some work to be done there. the templates are also a bit over size to account for the material consumed in the hot wire process. the outboard templates also are thinner then the true airfoil to allow for the extra plys that hold on the winglets. but you already know all this because you have a set of the plans and have studied them. right

 

if you do change the type of foam you will be flying an untested wing that you don't how it will act in the air. but you will be doing flutter analysis on the wing before you fly it. right. there is a plane that was built with a "better foam" and that airplane was falling apart and delaminating and was to cut up into pieces before it killed someone.

I have a small soft area under the wing along the fusalage on the left side. I guess this is delamination but it is very soft and spongy. How should I go about fixing this and is it a ver yserious concern until it is fixed? Here is a picture I took: http://img132.imageshack.us/img132/2238/imag0063k.jpg

stick it with a straight pin, if it is paint it will go through, if it is glass the pin won't go through. if it is because of a fuel leak the fuel will leak out and you will know. looks like paint blister to me . have seen this a lot.

actually all i said was the wing patterns could be machined and molded in a few days

 

i never said anything about re-engineering, or even making the wings in that example

 

also completely re-engineering it isnt necessary if a foam core is used, as the construction will actually be very similar, just think of it as having your existing foam core, then laminating your sparcaps and outerskins in one operation, then enclosing it between 2 wing shaped molds and squeezing it around the core with a hundred or so tons of pressure and heating to cure, causing the outside to be the exact shape of the wing without need for sanding and floxing to get it smooth

 

and if in the future i do want to try build a ribbed wing the existing molds do not require altering either as the outside shape is unaltered

I am not trying to discourage you from building or thinking of a new way to build a plane but,

I don't think you totally under stand the complexity of the wing as designed for the long or cozy. the wing skin is not just a few layers of glass and the internals of the wing are not just a foam block shaped like a wing. the wing spar is made up of many layups using the male foam blanks as a core. the wing skin is made up of several layups that include the the skins, the attach reinforcements and layers to hold on the winglets. if you mold the wing skin and then install the reinforcements and the winglets attach layups on the outside of your molded part you will still have to refill about half of the wing to get a finished wing. if you do mold the wing skins and put the extra layups for the winglets on the inside of the wing skin then the wing would need to be made with the winglets as part of the wing, all one piece. however you do it if it is not done to the plans then it is a different wing structure, would need to be engineered for that type of construction and tested to destruction to prove it is safe to fly. there is a big difference between the F1 parts you are building and the aircraft structure. if an F1 part fails you pull over and let the race winner pass. if an aircraft structure fails you will be the one that is doing the passing.

Hey Lynn it can be done, they do glider composite wings in two days. But they use molds and the guys that work on them are very fast. You got to love those German.

 

But I don't know about the Berkut of Ez wing....

i don't doubt that it can be done with a full crew of experienced people. but the glider wing is engineered to be built that way and the ez wing is not. so i doubt anyone can re-engineer the ez wing, build molds, build a spar and wing skins and assemble it in a few days. assemble it in a few days, Yes and all the other work required did not count because it was done in your free time?

you could say the same to anyone here then,

infact why bother building at all? just go buy a share in a piper

 

 

i am curious to know why some of you are so negative about the way im planning to build my aircraft

 

but thanks to the messages of support i have recieved in PM

we are not negative. we just have been there and done that. you said and i quote "a lot of what im doing is to save time for myself aswell, i can machine and mould the wings in a couple of days". you and an army of guys maybe. if you had said a couple of months I might believe you have really grasp the magnitude of the project. even if you are the fastest composite guy to ever roll out the prepreg, the composites parts are only ten percent of the project. the cost of the molds will out way the cost of the parts. molded parts are made and assembled with different methods then the way the moldless composite aircraft are built. if you use molded parts then there will be a lot of re- engineering to be done to insure a safe aircraft. just because the part came out of a mold made from a cnc'd plug and all the glass was prepreg and cured in an autoclave doesn't mean it is better and stronger then the hand made part. first it needs to be engineered to be better and then it needs to be tested to prove it is better and only then will people really believe it is a better part. why does it need to be better? ask any Rutan canard pilot if his plane would fly any better if the parts where made in a mold and he will tell you that it can't get any better.

A little of both. My Nav antenna (one) in the canard is foil.

I'll have a high gain in one winglet and a foil in the other for the COM.

 

The jury is still out on the transponder.

what people don't realize is that the name high gain is just advertising. the antenna you built is a "quote" high gain antenna the guts are the same. its a simple dipole antenna inside the fancy black packaging. I have heard from many that say their home built one works better.

Thanks Wayne. I'm familiar with that line of antenna. That's actually the direction I was leaning. I'm sure I'll have enough room in the nose.

thats the one I had at first and had problem at certain angles replaced it with the homemade foil tape one and the problem went away. the foil tape cost about 1/100 of the fancy one. TMann I thought you where making your own antennas. the transponder one is only 1/16" thick and about 8" long

No

 

Yes, as stated, the berkut design has the antenna protrude through an oblong hole (.5" x 1.0") through the landing brake.

 

More so than aluminum?

Yes, one of the things that dave is doing with his berkut is antenna testing for government contractors. It seems that the carbon structure of guided weapons hung under carbon aircraft causes a problem with the guidance signals

if the fuselage is glass then the best place for the antenna is in the nose. you can use a foil tape dipole and save some weight and antenna wire. no antenna sticking out at all. mine is in the nose on the right side just in front of the canard and has always worked. also the radiation just under your butt is not a good idea

The Berkut landing brake came prefabricated and I do no know how it was constructed (layup schedule etc.) My nose strut cover is CF and I really like the way it came out and would like to do the same on the landing brake.

 

Yes, that is what I'm going for here. I have some extra CF and I'm trying to build some small parts with it to gain some experience prior to building my wings. So far it has been a dream to work with. I really like it.

 

 

Sounds interesting but I think I'll stick with it projecting through vs. actually being part of a moving panel. I don't suspect that this arrangement would impare functionality.

is your fuselage carbon? if so you will need it to protrude out the bottom as the radar station is going to see the signal from an angle that is mostly horizontal . any carbon between you and the station in a horizontal plane will block the signal. with carbon wings even a slight bank with a low wing in the antenna line of sight to the station will block the signal.

Well, actually, there are more Velo's registered with the FAA than COZY's. About 330 Velo's to 210 COZY's. So that's not a good comparison.

 

I do agree with you, Lynn, however, that if the desire is to replicate something along the lines of a Berkut in a molded kit, that the result will be approximately the same as Berkut - turning a bunch of $$$ into a smaller pile of $$$. It's not possible to sell the kits for a 2-place composite tandem high-performance plane for what Vans can sell RV kits for.

 

But hey, there's always people with more $$$ than business knowledge - just witness 90% of the folks in the homebuilt airplane kit market.

just to keep it straight . I know there are more registered but I said there are more cozy's then velo's being built. as it takes a lot longer to build a cozy then a velo I believe that ratio of registered will change. it also seems that people are also crashing velos at a higher rate.

Look here:

 

http://www.maddyhome.com/canardpages/pages/voolivrebrasilia/exindex.html

thats just like the velocity gear. the gear can be made from scratch. I did mine in a similar way but with carbon. it can be done but it did take an extra 1000 man hours to do the complete system. would I do it again. No, it adds a lot of complexity for very little gain.

Just out of curiosity and possibly a bit of market research

 

would there be a market demand for a molded kit aircraft ?

 

the reason i ask is because im going to build mine is this manner as i work for a composite company and have full access to CNC, claves and lots of other things

 

so the options i have available range from fully claved and molded wings ect ect, to the lower tech bucket and brush were all used too

 

so really im curious to see if its just something to do for myself or if its worth making the extra effort to make the tooling extra durable for the extended usage of making parts for others aswell as possible clave usage

if people where willing to spend the extra dollars to get a kit Berkut instead of building the long ez from raw materials don't you think there would be more Berkuts then long ez's being built. if people where willing to spend the extra dollars on a Velocity kit instead of Cozy IV plans and materials there would be more velocity's then Cozys being built. but that is not the case.