Foam VRS. Built up

[RC Storick]

The numbers are in, I had a Viper wing from Viper 8 that was salvaged and I have my new Quickie wing out of foam. The quickie wing is 1 inch longer in span. (I have not figured out square inches) but basically the same size. The built up wing and the foam wing are finished (flaps-tips-controls) Built up is 15 ounces and the foam is 15.30. The built up wing has color and the foam one does not but both are covered and cleared.

Viper 8 weighed 49 ounces with a PA .65. I don't think this the quickie will be that light as I want a decent finish on it. Should be on its wheels by next week. Another one in less than 30 days.

Just a FYI. If you think that my quick builds are less than adequate I would not be ashamed to take any one of these to the NATS.

[Bill Little]

Hi Sparky,

That sounds like what Randy told me.  He said his foam wing Katana was 1 oz. heavier than his built up wing Katana, all else equal.

BIG Bear

[RandySmith]

Hi Sparky,

That sounds like what Randy told me.  He said his foam wing Katana was 1 oz. heavier than his built up wing Katana, all else equal.

BIG Bear

Those two were actually the exact same weight, but typically the same two plane when I do them in foam or built up are within  1 ounce of each other. the foam wing will weigh a tad more going into the fuse, but it is easier to finish a foam wing lighter.

Randy

[Brett Buck]

The numbers are in, I had a Viper wing from Viper 8 that was salvaged and I have my new Quickie wing out of foam. The quickie wing is 1 inch longer in span. (I have not figured out square inches) but basically the same size. The built up wing and the foam wing are finished (flaps-tips-controls) Built up is 15 ounces and the foam is 15.30. The built up wing has color and the foam one does not but both are covered and cleared.

     That's roughly consistent with what we have always gotten. Done properly, the weight is nearly a wash. The finish is usually a bit lighter, and the bare airframe is a bit heavier.

    Brett
   

[Larry Fernandez]

First news I have heard of this issue. I have never built a bendy wing nor have I had one fold EVER

I wish I could say that.

Larry, Buttafucco Stunt Team

[Derek Barry]

No matter how hard I try, my foam wings always come out much heavier than the built up. The wing in my cutlass was 11 oz. before it went into the plane. That is with flaps, hinges, control horn, and bellcrank. My foam wings are always more like 15+ oz.

Derek

[Doug Moon]

The only issues I have ever had is pilot error.

Dang, I wish I could say that too....

I have built some real dogs over the years, managed to compete with them though and learned alot from them but in the end they were still dogs.... 

Well, actually, in my case it is pilot error because the pilot is also the builder....Haha 

[Steve Fitton]

Read slowly! I never fail! This will not turn into a bash Sparky thread. You can take it elsewhere you do not make yourself look any better than you are.

Not bashing, just some good natured poking with a stick.

[Derek Barry]

Read slowly! I never fail! This will not turn into a bash Sparky thread. You can take it elsewhere you do not make yourself look any better than you are.

I don't think he was saying your plane failed but more that you have failed to accomplish your goals because of "pilot error" which is pretty much true for everyone in stunt. Not an insult...

Derek

[RC Storick]

Nobody said the plane failed.

Wasn't Viper 8 the one that had issues at the Nats with inconsistent corner because it was bending so much? Was that the light grey one?

It is still stiff and always was.

[Airacobra]

I will concede the foam wing is certainly heavier. In my case, I just like the ease of building the foam wing over a built up wing. I don't know of anyone that has more experience than Bob Hunt on foam wings and I think he has had some real success with them. He will more than likely tell you the same thing, that the foam wing is indeed heavier, but there are some real advantages as well. Recently, I have been in a search to find a way in which to make the foam wing lighter. As I was doing so I came across Dee Rice's article in the May 2009 Flying Models in which he uses the foam core and sheets the wing. After installing a spar, he removes all of the foam with the exception of a 3/8 wide section towards the rear of the wing. If Dee is on here, he could probably give you a more in depth description, but the article is well written and includes a lot of photos. I have not tried this type of wing yet, but I can tell you that I am going to. There are advantages/disadvantages to each type of wing we build and I have to tell you I enjoy seeing what folks show up with at a contest.

[RC Storick]

I cleaned up some of this thread and I am trying to keep it informational. Foam wing in the build state is slightly heavier than built up. I can see in the finish state it might be lighter. The one area where it's way heavier is the wingtips.

How you can tell this for yourself is put the nose to you stomach and one hand on each side and roll it tip to tip. Do this on every plane and try to keep that inertia down.

[Airacobra]

Bob, you using just a block of wood, then hollowed out? Check out that article if you get a chance, not sure it will be WAAAAYYY lighter but an interesting approach nonetheless.

[RC Storick]

My wing tips are approx. the same for both. Its just the volume of wood, glue  and foam towards the tips.

[Brett Buck]

I cleaned up some of this thread and I am trying to keep it informational. Foam wing in the build state is slightly heavier than built up. I can see in the finish state it might be lighter. The one area where it's way heavier is the wingtips.

How you can tell this for yourself is put the nose to you stomach and one hand on each side and roll it tip to tip. Do this on every plane and try to keep that inertia down.

    It can actually be measured in a similar way - suspend the airplane with a bit of music wire, so that it twists. Then measure the oscillatory frequency, compare to the oscillatory frequency of an object of known moment of inertia.

   All else being equal, at the same weight, this airplane will be substantially stiffer than the built-ups, because the wood in the wing is in a more effective place - more at the edges than the middle. Even better, when it does flex, it will flex without inducing much trim change. That's the real advantage of foam wings, even more than the ease of building it straight.

    Wings are not "stiff" or "flexible" as a binary function, they are all flexible to one degree or another, and flexible enough that it matters. They also change shape from day to day, and hour to hour. It has been our experience that the foam wing airplanes are much more consistent because it barely moves based on the conditions.

   Finally, and this is not intended as "Sparky-bashing", exactly the opposite - if you think piloting is your only issue, I can help you get 25-50 points in a few days using this airplane. Without even seeing it fly. I suggest the same advice I gave you at the 2009 NATs to start with. We can do the rest of it off-line if you want.

     Brett

    

[Bill Morell]

It is still stiff and always was.

That's what my wife says..........

[Brett Buck]

My wing tips are approx. the same for both. Its just the volume of wood, glue  and foam towards the tips.

  Exactly. This is the result of a larger 'radius of gyration', the same reason why a short nose with a heavy engine is easier to start/stop than a long nose with a light engine, given the same balance and everything else.

     Brett

[MarcusCordeiro]

It is still stiff and always was.

That's what my wife says..........

  ....

Marcus

[RC Storick]

 Exactly. This is the result of a larger 'radius of gyration', the same reason why a short nose with a heavy engine is easier to start/stop than a long nose with a light engine, given the same balance and everything else.

     Brett

That might be so but it still feels like a brick in the nose. I would take the lighter version and longer nose.

[Steve Fitton]

That might be so but it still feels like a brick in the nose. I would take the lighter version and longer nose.

Cue the Yoda comment!

[RC Storick]

 Can we expect a front row plane from you this year?

[RC Storick]

Here is the deal If you want to post bs do it else where! I am done with it. The next comment from anyone not concerning a foam wing gets a free vacation. And to Eric I just tell it like it is.

[David_Stack]

Good Afternoon Robert,

  I'm curious, how does the spar in the foam wing compare/contrast to that in the typical all-wood wing which you construct?  Is there a shear web in the spar construction of the foam-cored wing, or only top and bottom spars, with the foam itself serving as the sheer web?

  I assume the core has been hollowed to some extent, how much foam is typically left (thickness) to support the outer skins?

r/
Dave

[RC Storick]

This is a tri cut core. Meaning there are 3 holes running tip to tip. It has about 3/8 thickness supporting the skin. I did not use any wood spar in this wing. Just CF the center and made sure the joint was tight.

Like this

[Curare]

Sparky, what do the tags do on the LE & TE of the outer templates?

How do you stop the templates from sliding around, giving you wash-in/out?

Sorry for the questions, just trying to learn is all.

[RC Storick]

Sparky, what do the tags do on the LE & TE of the outer templates?

How do you stop the templates from sliding around, giving you wash-in/out?

Sorry for the questions, just trying to learn is all.

Im not sure I don't cut foam. Ask bob Hunt. these were the only examples I could find.

[Curare]

Ahh, sorry, I thought you'd cuttem yourself.

[David_Stack]

Greg;

 I 'think' they may be nothing more than 'photo props' (literally and figuratively...).

 If you look at the image of the inner templates, there appears to be a trace of a shadow, as if they are standing proud of the surface they are sitting on.  I suspect what you are seeing on the outer templates are actually small 'risers' to get the templates free of the flat surface they are sitting on, so they photograph better.

 That it the only thing I can think of, for they are unlike any 'lead-in' or 'lead-out' template ramps that I have ever seen.

 Note also the small holes in the templates, my guess is that whoever uses these affixes them to the foam using small nails or rivets, and that is how they are prevented from moving about (your earlier question).

r/
Dave

[Crist Rigotti]

Sparky, what do the tags do on the LE & TE of the outer templates?

How do you stop the templates from sliding around, giving you wash-in/out?

Sorry for the questions, just trying to learn is all.

Those "tabs" if they are a part of the template are probably used to locate the template, fore and aft, on the block of foam prior to cutting.  They are simply locating tabs....just a guess though.

[peabody]

There are some that sheet the foam first, THEN core it.....thinking being that more pressure can be put on the un-cored piece, with less distortion.
Windy built a light (especially for him) Cardinal for the Lincoln Nats, where he figured weight would be more critical because of the altitude, by sheeting a built-up framework.
I believe that Eric Viglione did that with his current plane.

A sheeted wing would seem to me to have a consistent airfoil while a built up and tissued would "sag", changing the true airfoil?

Thanks

[Mike Anderson]

The tabs on the templates are there to give the wire a place to rest and make sure that both ends 'start' cutting at the same point.  On the other end, they keep the wire from falling off the template before the other end reaches its end of cut.   Some people cut from front to rear, some start at the rear and cut towards the front, but whichever direction one uses, it makes it easier for one person to cut a foam wing.

(at least that is why my templates all have a similar device)

[Curare]

Well, some of you are right, and some aren't.

I traced the photo back to winship models, and read Dan Winship's article of foam wings, they're stops as Mike Anderson says. Personally, I've never seen the need for them, but I may give it a try on my next core, if only as a starting rest.

For those that care:http://winshipmodels.tripod.com/myfav3.htm

[RC Storick]

That might be so but it still feels like a brick in the nose. I would take the lighter version and longer nose.

It was pooh poohed about the light weight and long nose but I am pretty sure the current world champ (Igor) has the same feelings as his nose moment is 11.5 with a light motor. Worked for him. Oh I forgot that Orstes said with the battery as far back as he can get it "he can drive deeper" .light weight motor and long nose as well.

I guess its only if I say something its no good.

[john e. holliday]

That plane is going to look even better with the finish on it.  I like it.

[Brett Buck]

There are some that sheet the foam first, THEN core it.....thinking being that more pressure can be put on the un-cored piece, with less distortion.

I thought everyone does that now. For the reason mentioned.

Windy built a light (especially for him) Cardinal for the Lincoln Nats, where he figured weight would be more critical because of the altitude, by sheeting a built-up framework.

   Al Rabe was also an advocate of fully-sheeted built-up wings. I did a few Noblers that way - once you get the LE and TE sheeting on, it takes only a little bit more to omit the capstrips and put on a full sheet. The big advantage is the weight saving in the finish, just like the foam wing.

    Brett

[RC Storick]

That plane is going to look even better with the finish on it.  I like it.

Thanks Doc. I am thinking about a super elaborate paint scheme. Black base. Here is the decal for it. The name of the plane is QV. I will do it in gold leaf and I am always behind the 8 ball.

[Avaiojet]

I would reduce the highlite on the "8" ball, it takes away from the "8".

But that's me.

[Howard Rush]

Al Rabe was also an advocate of fully-sheeted built-up wings. I did a few Noblers that way - once you get the LE and TE sheeting on, it takes only a little bit more to omit the capstrips and put on a full sheet. The big advantage is the weight saving in the finish, just like the foam wing.

Hmm.  You also wouldn't need zigzag ribs for stiffness.  A fully sheeted wing especially appealed to me the fourteenth time I sanded through a capstrip edge on one airplane, but that's not as big a factor with Polyspan, where we merely have to contend with the Fuzzies.