McLeodAviation

My Feedback: (70)

Hi Phil,

Great job!!! Your wings are almost finished and thats a great accomplishment! Those are some long wings! They look longer without the polyhedral.

I emailed ACP-Composites today and they have shipped the carbon fiber for my CB4 spars. I should receive tomorrow or soon after and I can begin building my wings.

What type of glue are you using on your wings? Did you hold the upper sheeting in place with tape? Did you use the included spruce flap stock for your trailing edge?



Cloudbound, Mike

RBeach

HI Mike,

I noticed that you inquired of Phil about glue for the wing. What we have found works well with the Carbon Fiber Spar Caps is as fllows:

1. Bottom Carbon Fiber Spar Cap, glued to lower balsa wing sheeting; Epoxy filled with Cabosil and or micro baloons. I particularly like West Systems, which can be purchased over the web or at most serious Marine Supply Houses. West System also has their own line of addatives.

2. Wing ribs glued over Lower Spar Cap and to lower wing sheeting. Normal thin CA works well here. or use the same Epoxy as above.

3. Blasa Block shear web connectors to bottom Spar Cap and between Wing Ribs. This also includes Upper Spar Cap to Balsa Shear web Connectors (Balsa Block w/ vertical grain); Epoxy as in No. 1 & 2.

4. Upper wing sheeting, taped in place after glue is applied; Yellow Glue (Alphatic Resin.)

I hope that information helps you out MIke.

Cheers,
Roland Beach

Culver10

Hi Mike,

I used CA for most of the wing. I pinned the 1/16" balsa leading and trailing edges plus cap strips down. I tacked them in place with thin CA. I then attached the bottom spar cap in place using my 6 foot ruler to align it. The 3/8" spar cap is scarfed to the 1/4" spar cap. I pinned all of the nose ribs in place and then CA'd them with thin. I then planned and fit the continuous spruce web. I glued it with thin CA and then applied some medium CA fillets at the ribs. The top spar cap was scarfed and glued. The rear diagonal ribs were then cut and fit and glued with thin CA. The rear diagonal ribs and the 1/4" rear false spar had to be sanded to final shape. I used a 28" X 2.75" X 3/4" straight piece of Sitka spruce for a sanding board. The leading edge was glued by tightly tapeing the top sheet to the spar. I used 1.5� wide tape and wrapped it around the spar. Once the whole thing was taped, I hinged it up and applied yellow aliphatic resin to the ribs, spar and leading edge. The front was tightly taped to the bench with lots of masking tape. I did the leading edge and aileron false spar last night so I will post some pictures for you.

Phil

Culver10

Hi Mike,

I did use the spruce leading edge, it worked out great. Enclosed is a picture of it at the scarf joint. I found that my razor sharp block plane worked great for shaping the rear false spar and spruce leading edge. Enclosed are some pictures of the leading edge tape.

Culver10

I got one side of the fuselage started last night. I made my own 1/4" square spruce from some 30 grain per inch Sitka Many of the reports claim that the plane is tail heavy. I decided to add 1.5" to the nose. I would rather add a little wood and more moment than lead. I have not decided if I will sheet the whole thing like Ray suggests or not??

erich44

I thought you already had the fuselage completed??

erich

Culver10

Mike has his fuselage done, I just started mine.

Phil

McLeodAviation

My Feedback: (70)

Hi Phil,

I received my carbon fiber strips and have started building my right inner wing panel. Have you ever tried to cut these thin carbon fiber strips? Man they are tough!

I also relocated my wing rods for 2.5 degrees dihedral.

Couple questions for ya! Are you using spoilers and what type of hinges are you going to use for your flaps and ailerons?

Soon as I get a little more finished I will post a few pictures.

Cloudbound, Mike

Culver10

I made some carbon fiber flap gap seals for a Mooney several years ago. They were about 3" X 48" X 0.025", I used a wet diamond tile saw to cut them to shape after I layed them up on a glass door. Maybe a Dremel with cutting wheel would work well for these little fellows??

No Spoilers.

I was going to try using the Ultracoat Lite for the hinge. The built up flaps and ailerons want to warp when you glue the final top skin on with the Aliphatic glue. It must be the water in the glue?? I was able to straighten them by wetting, bending and clamping them in the opposite direction of the warp. They are so light that the iron on film coating will straighten any warps also.

The fuselage is more done than not!

Any idea of the weight comparision of carbon rods to steel rods? The steel rods seem very heavy.

I will try to get some pictures of the fuselage with the wings on, it looks really big!

Phil

Culver10

I got the top front of the fuselage shaped last night and put the wings on to see how it looks! The longer nose is quite noticable now, I built the rear truss fuselage like a Cub and it is extremely stiff and does not twist. I still have to mount tow hook in nose and bottem, install control rods, finish tail mount and then install bottem.

ejett

My Feedback: (4)

Man! That construction looks really nice. I'll be watching for flight report!

EJ

McLeodAviation

My Feedback: (70)

Hi Phil,

I think carbon wing rods will save alot of weight. The steel rods are very heavy. I might buy carbon wing rods too.

Wow, great job on your Cloud Bound 4! Looks like yours might be finished before mine.

Cloudbound, Mike

Culver10

I tried some carbon 5/16" carbon tubes (not rods) in the brass tubes last night at the hobby store and the carbon is way too tight. I did not have my micrometer, but the carbon must be several thousands larger than the steel rods. I guess I could sand them own in the lathe to make them fit.

Have you got much done on your wing yet Mike? It takes much longer to figure things out and plan things, than it does to build it! I built the last wing in two evenings, it is not sanded yet or the ailerons are not built either.

Have any of you folks looked at the Big Genie by Harley Michaelis?? [link]http://genie.rchomepage.com/[/link] What a great plane! I am going to build one of these next!

ejett

My Feedback: (4)

The rods should fit better than the tubes because the rods are made to O.D. size and the tubes are, I think, made to tolerance on the I.D.

You should try the rod first. I am going to get some for my planes, but it isn't here yet, so I can't try it for you.

EJ

Culver10

I weighed the steel rods and they are 9.5 oz!! That is over 12% of the design weight!! I just found a site that published the density of thier carbon fiber rods =0.054 lb/in^3 Steel = 0.284lb/in^3 9.5ozX0.054/0.284=1.86 oz I will be ordering some soon!!!

McLeodAviation

My Feedback: (70)

Hi Phil,

I have all lower sheeting cut and pinned down for one inner wing panel. Tonight I cut some new plywood ribs to replace the balsa #2 and #3 ribs. I also cut new #1 and #4 ribs from higher quality 5-ply. I am using the old ply #4 rib in the #5 position. Now my first 5 ribs are plywood! I also cut identical ribs for the other wing. Like you said, the other side will go together much faster than the first.

I might start gluing tomorrow. Think I have decided on a suitable servo and linkage arrangement. I'm also not using spoilers. With the large flaps I don't think they are needed.

The steel wing rods are seriously heavy! Hope we can find lighter ones. A carbon tube might be strong enough? I'd like to use solid carbon rods.

Yes, I have seen the Genie sailplane. Very unique design and very strong. I like the Genie too!

Cloudbound, Mike

ejett

My Feedback: (4)

I would think two 5/16" CF rods would work fine and are a good idea. The downside of CF rods is they break suddenly instead of bend. Nicks and scratches are serious issues on CF joiners as well. Make sure the openings of the receiver tubes are nicely beveled and smooth on the inside to spread out that point load on the joiner. I would get enough CF to make two sets of joiners. Carefully inspect them for damage before every flying session.

One thing about having both sets of joiners is that you could throw in one or both steel joiners if conditions warranted the extra weight.

I think the weight saving on this plane is worth the effort and expense of purchasing the CF joiner rods.

EJ

McLeodAviation

My Feedback: (70)

Hi Phil,

I now know why you didn't use the spruce trailing edge flap stock included with the kit. Because it doesn't fit!!! It's too small unless I stack it on top of an extra piece of balsa. It also will not make a nice trailing edge angle without alot of sanding. Maybe I'm just not sure how Ray uses the flap stock? Looks like you used a balsa trailing edge like shown on the plan. Maybe I will too?

Cloudbound, Mike

Culver10

I never got any spruce trailing edge stock! I made mine out of balsa, just like the plans. They are very light!

McLeodAviation

My Feedback: (70)

Hi Phil,

Hmmm, Guess I didn't get spruce trailing edge stock either! I had it confused with the spruce leading edge stock. I always thought leading edge stock is rounded but not in this kit!

Ray's parts list says the balsa triangle stock for the trailing edge is replaced with 1/4x5/16 spruce flap stock. Apparently neither one of our kits came with this spruce flap stock.

Did your kit come with Ray's 3 page parts list and modification instructions? This was also missing from my kit and he emailed the pages to me!

Cloudbound, Mike

Culver10

I did get the 3 page deal. The leading edge is very triangle shaped on this airfoil. The block plane worked great for fine tuning it. from the root to about the first 1/3 of the wing, I had to use a little Balsarite filler to fill the gap between the balsa skin and the spruce LE. It will make more sense once you glue it on.

Culver10

I dusted off my old Mechanics of Materials textbook and did some number crunching for steel vs carbon fiber. I used 40000 psi for the yeild strength of the steel and 200000 psi for the carbon fiber. The Cloud Bound was designed for 1/4" steel rods, and Ray supplied us with 5/16" rods. I figured out the bending moment to destruction/yeild strength.

1/4 steel rod =58lbin
5/16 steel rod =119lbin
5/16 carbon tube=404lbin (0.236" I.D.)
5/16 carbon rod =598lbin

My local hobby store (very evil place, according to my wife) does not have solid 5/16" carbon rod, but they do have the above mentioned carbon tube. I am going to try it out on my plane and I will let you know how it worked!

Phil

McLeodAviation

My Feedback: (70)

Hi Phil,

I just noticed Skybench sells 5/16 solid carbon fiber rods for $12.00 each. Up to 12" length.

www.acp-composites.com sells 5/16" carbon rod for $12.00 however they are 24". Half price!

I'm going to order solid rods for my CB4.

Cloudbound, Mike

ejett

My Feedback: (4)

Mike:

I would expect the carbon rods to fit the tubing better than the tubing Phil is planning to use. Either way, the additional strength and lighter weight could be significant. You fellows need to be sure to inspect that rod/tubing regularly for wear, tear, nicks, etc. The CF is very strong but it is sensitive to surface damage and crack propagation.

EJ

McLeodAviation

My Feedback: (70)

Hi EJ,

Thanks for the tips! I will file or sand the brass tube ends to help prevent fracturing the carbon rods.

No progress to report on my Cloud Bound 4 project. Too busy this weekend!

Cloudbound, Mike