barto

Looking very good.

About the open fuselage: it is quite time consuming but it is the strongest way to build an airframe.

Keep up the good work.



Bart

Rick K

My Feedback: (6)

Hello Mike, My Skybench "viking" also came with a 'Hardwood' (maple?) nose-block, I used my DeWalt orbital sander to rough shape it. Close shaping was done with a regular sanding block with the final shaping done with a foam backed sanding pad. As to using a balsa substitute . . . If the plane is likely to be tail heavy I'd rather use a stronger material up front and a battery with a greater capacity as 'usefull' ballast rather than packing dead weight lead. I hope you're going to strengthen the 'wrist' of the fuse (area just forward of tail group) in some fashion. . . Maybe you could place some 1/8" sheet balsa inside the stick fuse, 6" long, half foward of the Horz. stab LE, half behind. This has been the only area on any plane I've ever built that I've had structural failures with, it's happend to me with four different plane types.
Rick K
LSF 6493

McLeodAviation

My Feedback: (70)

Hi,

I will consider reinforcing the wrist area but I think is strong enough.

Cloud Bound 4 update,

I have joined the forward fuselage section, glued front nose blocks, and roughly sanded the nose. The block in front of the canopy was not included in my kit. I made my block from 4 pieces of 1/2" scrap balsa. I also decided to add a couple lead weights to the nose. My Cloud Bound 4 is beginning to take shape!

PICTURE 1, Used a couple lead weights from my tackle box. I drilled and carved the nose blocks to accept them.
PICTURE 2, Lead weights are epoxied in place.
PICTURE 3, Blocks epoxied to fuselage and all roughly sanded to shape. Still needs more sanding but looks pretty cool.

Cloudbound, Mike

barto

That looks very nice, keep those pics coming.



Bart

McLeodAviation

My Feedback: (70)

Hi Rick and Bart,

Thanks for the complements and all the great tips. They help keep me motivated to finish my Cloud Bound 4 sailplane.

More pictures soon.

Cloudbound, Mike

Rick K

My Feedback: (6)

Hello Mike, Just a quick note to let you know I'm still here and looking at your posts when I have some time. School started three weeks ago for my girls and the PTA has been imposing again on much of my time, that plus my 'room parent' duties for both of my little girls classes (helping out grading home work, cutting out craft stuff . . .etc.) and taking care of our 10mo. old baby seems to take up just about all of my time these days.

You seem to be making great progress on your kit, and from looking at your pix, you do some fine work. Oh, did I say in my 'tip' baking soda? I ment to say baking powder. I guess that what's happens when you're trying to type and 'referee' kids at the same time. Tonight isn't much better, I have a good chunck of my in-laws here for the weekend . . . It wouldn't be so bad if only they could speak more english . . . I know enough spanish to understand when their making fun of me tho. Not a happy camper this evening. Very worried that when my wife and I go to the race tomarrow ( the Bush race here in Fontana, Cal. speedway) their kid's will be getting into my stuff. One of my other e-mail pals gave and sent me the tickets from way, way up in the northen part of our state . . . felt his health was not good enough to go both days. I can't begin to say of how kind all of the people I've sort of met here have been to me. From sending copies of long lost inst. manuals or making parts I don't have the equipment to make myself with out any charge. Neat hobby we have huh?
Rick K
LSF 6493

RBeach

Hi Mike,

Educate me if you will. I have studied all your photos and your construction is neat clean and well thought out. In looking at the aft portion of the fuselage none of the web members line up to adjacent panels. I would have thought to transfer the loads properly one member would lead directly to a connection of a member on the adjacent panel.
What's happening here?

Roland Beach

McLeodAviation

My Feedback: (70)

Hi Roland,

I also noticed some of the upper and lower members are out of place. I started placing them as shown on the plan however as I worked toward the rear they got a little out of place. Guess they are not placed for optimum strength however is very strong. If I build another CB4 in the future I will pay closer attention to the upper and lower placement.

Hi Rick,

Free NASCAR Busch tickets, You Lucky Guy! I am a NASCAR fan and have been watching races on TV for many years. Still makes me sad my favorite driver was killed, God bless Dale Earnhardt!

This hobby has some of the nicest people, many will go out of their way to help someone they have never met.

I plan to work on my Cloud Bound 4 this evening. I will post more pictures soon.

Cloudbound, Mike

forrest adams

regarding cb4, thought i'd add my 2 cents.
a trim ballast box is a nice feature to build in to the plane - i just build a box with a small hole in the top and add/subtract lead shot as necessary - cg is a matter of personal preference and i think that having the ability to make small adjustments is a nice idea.

RBeach

Mike,

Since you haven't got around to the wings yet, it might be worth checking out the posibility of using Carbon Fiber cap strips in the wings of the CB4. To my way of thinking the wing can't be strong enough when you are working with winches. As a comparison the Houston Hawk uses .060" thick x 1/2" top spar cap and a .030" bottom spar cap. The hawk has a `126" wing span where you have, I believe 144". The cap strip size would be close. The cost of the cap strips in a Hawk is $30.00. The other thing is, I have seen Jack's Womack's and Alan Jones's Hawks take some terribly licks and come up with no damage. It's worth thinking about. Alan Jones had a spoiler pop open and he nosed in at high speed and literally buried the nose. He bent the steel wing joiner but didn't damage the wing. That's strong.
I don't know how this might effect your legality to enter Nostalgia events but it certainly would make it strong. It would probably only add 1 to 2 ozs. to the total weight of the plane.

Cheers,
Roland

Rick K

My Feedback: (6)

Hi Mike, Geez . . . ya don't take a look for a few days and everything changes! Took a little while to find the reply icon . . . The race was great, The tickets my sailplane e-mail buddy sent were great. Right above the end of pit row where it rejoins the track in section 78 row 38 seats 1& 2, what a view, lots of action going on to look at all at the same time. We live only about three or four miles from the track, we can easly hear them from here when theyr'e running, so the drive there and back wasn't a problem either.

Oh, we're supposed to be talking sailplane . . . Still haven't decided how I'm going to do the spoilers (deploy them) I really don't want to do the 'strings and springs' method but I'm a little hesitant to put servos and direct linkage in the wings, mainly because Iv'e never done it before . . . so I just waste time doing nothing but stare at the wing and think about what to do. I can't do anything more untill I decide (and save up some dough to buy the servos if I go that route) Nothing like being indecisive huh? How about some opinions out there? What do you guys think? Any advice as to the servo behind each spoiler method? What size and strength servo should I use?
Rick K
LSF 6493

McLeodAviation

My Feedback: (70)

Hi everyone,

Thanks for more great tips. A ballast box is a great idea and I am seriously thinking about adding carbon fiber to my wings.

The CB4 has a very unusual spar design for the wings. I will have to study the wings and decide how to add carbon fiber cap strips. I also need to check if modifications with carbon are accepted at Nostalgia Sailplane Events. I may never fly my CB4 at a woody contest but I want to keep her eligible.

I have not completed much on my CB4 the past few days. I glued some triangle stock under the top block. I cut the fuselage bottom for the hardwood tow hook anchor. This kit comes with a tow hook that is screwed into a hardwood block. Has no lock nut or blind nut. I don't think this is strong enough? I need to buy or make a better tow hook. Rick, are you using the tow hook supplied with your Skybench Viking kit?

I thought about changing to larger aluminum wing rods but think I will use the 5/16" steel rods supplied with my kit. Rick, did your Viking kit come with 5/16" steel wing rods? Are you using them?

I can't help you with your spoiler dilemma, I have never built a sailplane with spoilers before. I was thinking about not installing spoilers on my CB4 because I've heard they are not neccassary when using large flaps. What do you think?

Cloudbound, Mike

RBeach

Hi Mike,

Glad to see you are thinking about the carbon fiber spars, it's the only way to go. If you are considering using the CF Spar caps, the combined thickness should be about .090" total thickness and no wood spar is used. If you take that from the wing depth (at the joiner rod) you should find you can use a 7/16" joiner rod, with room to spare. I asssume you recieved the drawing I sent by e-mail.
Heavy Duty tow hooks with nylon nut, washer and wood insert is $5.00 (+$0.50 Postage) from Don Richmond at www.highlaunch.com . Don also has an assortment of aluminum wing joiner rods. Check the site out, Don has all kind of Hardcore sailplane stuff.
I see Rick is having problems with spoilers. To my way of thinking one servo per spoiler is the way to go. It will normally require servo extentions with a "Y" connector. Almost any of the small servos will work. I normally use HiTec HS-55's. Although last year I bought a half dozen "NoName" Micro servos for spoilers. Bought 'em at e-Bay for $5.00 each. They have worked well no problems. The best feature is with a hard link from servo to spoiler the action is positive. When they close, It's positive and the adjustment of the servo is micro. This way it's easy to flush everything up. I for one would go with the servos.
As far as spoiler and flap, consider this; the spoiler will kill the lift but that does not mean it will slow the plane down. The flap at 90 degrees will also kill lift but it slows the plane down as well. The flaps can also increase lift at modest deflection and increase speed at modest positive deflection (normally 3 to 4 degrees up). If you have to make a choice the flap is the better way to go.
Let us know how the project is coming.

Cheers,
Roland Beach

RBeach

Folks, in the above post I listed the website for Hi Launch incorrectly. The website address is www.hilaunch.com Give it a try I am sure it will work now.

Roland Beach

McLeodAviation

My Feedback: (70)

Hi Roland,

Thanks for website and wing spar information.

I currently have too many options and modifications racing through my mind. I'm trying to sort things out and keep my project rolling.

Tonight I looked over my fuselage rear framework. I decided the front two lower members are placed wrong. These two were placed as on the plan but is not right. There should be one more member to even things up. I removed the first two members and replaced them with three new ones. Looks much better and is stronger. Three pictures below are of this modification.

Also I am guilty of placing some of the upper and lower members not exactly where they should be.

PICTURE 1, Built as on plan.
PICTURE 2, First two members removed and replaced with three new ones.
PICTURE 3, View over plan after modification.

Cloudbound, Mike

RBeach

OK Mike, I gotcha.

Port and Starboard side panels are identical, while the top and bottom panels alternate the direction of the braceing members. Looks much better! I would think as you go toward the tail end you would sand an awful lot of those trusses away to keep the tail as light as possible?
Looking good!
Am I corect in thinking that as a modification that Ray wants you cover the truss work with 1/16" balsa? If so it's a pity.
Is there any requirement that you run diagonal bracing members from top to bottom thru the interior of the truss?

Cheers,
Roland Beach

McLeodAviation

My Feedback: (70)

Hi Roland,

The rear truss section is to be slightly rounded. I don't want to round very much of the spruce longerons to retain as much strength as possible. Yes, Ray recommends covering the complete sides of the truss with 1/16" balsa sheet. This comes with the kit laser cut. I am not using this on my model. I want to cover the rear section with transparent Monokote like the original model.

The instructions nor Ray speak of adding extra members inside the truss. My brother had also recommended running some extra members inside the truss for extra strength. I think this is a very good idea. I will need to leave a path for the pushrods. Like many of my models, I am thinking of using two spruce stick pushrods for the ruddervators. After I install my servos and pushrods will check clearance for some extra members.

Cloudbound, Mike

forrest adams

regarding the 5/16" steel wing rods - i'd use them
1) you already have them
2) the mass moment of inertia with respect to rotation about the cg is minimal
3) the extra weight will help with penetration and may allow the airfoil to work more efficiently

it's been my experience that after careful analysis of many of the older designs that these guys usually knew what they were doing and had good reasons for most things they did regarding the design. i'm always skeptical when i see modifications to these older designs - especially when the 'new' designer does not have any data to support the change.

when in doubt, stick to the original plans - remember, man went to the moon in the late 60's - about the same time that these designs were being drawn up. today, we certainly have more data and better tools to work with, but i'm not sure we are any smarter.

ref, nasa's genesis crash

RBeach

Hi Forrest,

I have disagree with you about modifying old designs.

The designers of 30 years ago didn't use carbon fiber, fiberglass, Monokote or CA adhesive because it was not commercially available at the time most of the Nostalgia sailplane were designed. They used the available materials to the limit and made do with what could be found.

What is wrong with making a model stronger, easier to build and have better preformance. That's what you get with todays high tech materials.

Think about what you are proposing. Say for instance you can't use any new material that is develoved over the next thirty years. I think you would soon fall behind the pack.

Mike is building Cloud bound 4 because it is unique and he will end up with something that can't be bought in a ARF. The selection of materials is anything he desires to make improvments in the Original design. As a matter of fact Ray Hayes has made numereous modification to CB4. Most of his modifications are not even on the plans, simply notes in the website with a few photos. So, Mike is not building the original plane to begin with.

As we say; " it's his toy."

Cheers,
Roland Beach

McLeodAviation

My Feedback: (70)

Hi,

I love old model designs from the 1970s and 80s. They are very well designed and strong. Unfortunately wooden sailplane wings have a bad reputation for breaking. In the past I had two all wood sailplanes and lost them both to broken wings. I don't want this to happen again and will add larger spars and/or carbon fiber to my CB4.

I decided to use the 5/16" wingrods included with my kit. They are larger than the original 1/4" wing rods shown on the plan.

Cloud Bound 4 update,

I added triangle stock on both sides of the 1/4" balsa fuselage formers. I installed the upper fuselage stringers behind the wing. I sanded the fuselage near to the final shape.

Cloudbound, Mike

McLeodAviation

My Feedback: (70)

Hi,

I tried to upload a couple pictures in my last reply. I received the successful upload screen however my pictures were not posted. I tried three times and had the same problem. I will try again here.

This is strange, One of my pictures uploaded and the second one didn't. Oh well, I will try again tomorrow. This picture shows the rear stringers I installed.

Cloudbound, Mike

forrest adams

ronald

i said the changes must have data to support the mod (example - strength increase) that's a change that can be supported by data - read.

i did not say no new materials - i say modifications must be supported by data.

i suggest that designers do not make changes that do not result in improvements - please read my original post.

my other point is that new materials do not necessarily result in a better design if they are not applied properly - the design must be balanced - example: increasing bending strength without a corresponding increase in torsional strength can result in flutter.

btw, what's your background (education)?

gdjsky01

My Feedback: (2)

Hows things coming along???

McLeodAviation

My Feedback: (70)

Hi Everyone,

I have been busy with other stuff and haven't completed much on my Cloud Bound 4. I am also somewhat confused what to do about the CB4 tail construction and mounting.

I built one stabilizer and seems very weak. I can twist it very easy. I built with two spars and not one like on the plan. I also added some extra balsa sheeting however still seems not stiff enough. This stabilizer is made from a sandwich of three 1/16" thick strips. When finished is 3/16" think. This looks to thin for such a big model and I think has too much flex. When covered with Monkote might be strong enough?

I am thinking about building new elevators 1/4" thick.

My kit came with three very small nylon bolts for mounting the v-tail. I think they are to small and plan to use two larger nylon bolts.

My kit did not include a 1/4' ply tail mount like shown on the plan. I cut a new one matching the plan.

Cloudbound, Mike

RBeach

Mike,
If you sheet the leading edge say back to the first spar those stabs should stiffen up quickly. The Houston Hawk has a similar stab and when the leading edge, top and bottom, is sheeted it becomes very, very strong.
Watch the weight though. No one said this thing was going to be easy, did they!

Cheers,
Roland