Beeza

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Hi jetpack,
I've done planing on fuselages many times. So much, that I enjoy it, but it takes time to do right. Your idea of first laying a center strip to act as a stringer is correct. From there, lay strips on opposite sides to prevent pulling (warping) from one side or the other.

If the fuselage sides are done separately, pin them down flat first, then glue down your planking strips. I pre-cut mine, usually 1/16" narrower on one end than the other, or even up to 1/8" difference on longer strips. You can always adust as you go, maybe even adding an un-tapered one once in a while to keep things flowing as you need. Part of the fun is taing the finished rough fuselage and then sanding it out smooth.

If you do end up with creavaces where you might have needed to cut the edges to a bevel first but didn't, I've LIGHTLY doped very lightweight silkspan (or perhaps Jap tissue). that wil both fill the gaps and add more strength and smoothness.

There's nothing cooler than a wood-planked curved suselage when you're done!

Good luck with this neat project.

Beeza

injunnut1

Hey jetpack,
There are two great 1/2A size ducted fan Scale ships (both Free Flight) in the old Air Trails magazine, I think it was? Both are powered by the Cox Thermal Hopper engine ..... one was / is the Cougar Jet, and the other is one of my long time favorites the B-66 Bomber, although this B-66 Bomber is really a twin-jet-pod under the wing motors airplane this model design uses only one proplusion unit mounted in the main fuselage. As I recall both articles show the models actually flying and I think I remember even seeing LeRoy Cox himself witnessing the B-66 flights! I have both magazines hidden away somewhere around here feeding the Roaches and Silver-Fish and I will look for them, also I do believe I was lucky enough to fluke into one of the original full size plans as sold by the magazines' respective plan services ..... come to think on it, the Cougar might have been an MAN construction article back about 1955 or so? It seems I also remember a Sabre Jet 1/2A ducted fan model from way back in the early 1/2A days? I'll see what I can dig up from my archives if anyone is interested?
Donald Garry

jetpack

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Hi Beeza - Yep, I agree with you about a fully planked fuse. Seen one in a hobby shop years ago, and thought it was the coolest thing I seen that day. It reminded me very much of a wooden boat. That's something I've been looking into also BTW George. I've been searching model boat building instructions online trying to scoop up any info there, and building articles on boards like we have here on RCU, only catered to ship builders.

It helps to have a couple kits to reference to also, the two that I have actually have die-cut pieces and all numbered where they go on the bulkheads. I told you Berkeley wasn't shy on the balsa. Most of the planking strips that are die-cut look like they should have just been simply left up to stripwood - hardly any special shape to them at all, but some look a lot more intricate. If I tackle those two first, that should get me warmed up for the two I only have blueprints of where it will require more imagination on my part.

I wonder if Injinnut got caught in a collapse in his archives! I sure would like to have a look-see what he has there on the ones you mentioned there Donald. I think I recall seeing one on the Sabre so you might be right on that. The only other drawing I own of a ducted fan is a Panther, and it wasn't a kit - it was simply offered as a plan, and used a Veron blade and not nearly as snazzy as a Berkeley design, but looks flyable. Free Flight design if I remember right without pulling it out.

Look at the motor I found thats up on ePay. Seller says it's a MkII so I wrote him and asked if all that was original that was on it, because like we talked about never seeing them with a tank. We'll see what he has to say. It's a little beat up from plier marks and such, but I'm pretty good at metalwork with files and polish if they aren't too deep. I think that original Wen-Mac did have stepping in the tool marks like the Cox RR-1 with its spinners and tanks, so maybe this gig is all correct. I just cant figure out the spacing plate behind the crankcase. That is all new to my eyes.

Japanman

Hi,
I tried a two EDF fans. The better in terms of design was the wemotec one, but the plastic the stator is made of is cr*ppy, The problem I found with the edf stuff is that the pitch is too high for a 1/2Aglow engines, and the plastics are not designed to handle the oil/fuel and may go soft.
The stator in your plans looks good to me.
When I meant I`d send you a carbon fan, I meant one of the design I found worked well. no constant pitch, o.k?[8D]
I have only built two 1/2A DF planes but I found <ahem, after the first> that you have to be obsessive about weight to the point where the next prop plane I built seemed like cheating! With the D.F setup you have to build a fuse that is effectively double sheeted due to having the duct, and the engine and fan weigh more like an 09 with a prop, so you start out with a tremendous challenge to keep the weight down.... but thats kind of fun, I think.
both my ducted fan planes flew in a way that must be unique to DF planes in general. Kind of super smooth- like a rocket powered glider? But way cool, I find it hard to get excited about flying prop planes now.
Do make an RC flyer- even if you have to make 40% increased size version of one of the kits. You won`t regret flying it, thats for sure.

Stefan

jetpack

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Simple and lightweight is the only approach to having one of these to fly, and the challenge does not upset me one bit. I am one to always one to try things like this. Puts the building skills to a challenge and I think its fun too.

I have been working with balsa airplanes since a boy 35 years ago or so now and its one of my favorite materials to have to work with. Amazing stuff, and having to go outside those boundries where you have to use foam or anything like that I rather not work with. I guess the only exception there that I can think of is the birch aircraft ply I use to build my rc boats with, and that cant be helped.

I've thought about going with the standard open stringer approach to the fuselages, and using silkspan but went against that idea because if I build one to fly, I think it could use the strength. In landings if anything else. I could deal with fixing a wing or tail occasionally, but when the whole fuselage cracks its another story.

It would be good to have a durable fuselage that you can always go back and work from. Starting the motor is another factor why it should stay sheeted - it would simply be less of a risk breaking during handling. I can picture one single kickback with a starting wand and the whole thing twisting into a mess.

Stefan, hang on to your blade that you made for now, and lets see how far I can get with these with my building. If it looks like I can build light enough and have enough balsa left to try a flying model we can give it a go. Let's save that for you to experiment with, and maybe more can develop from that. I'll measure up that Berkeley impeller so you can keep that with your notes. I'll even give you thrust tube measurements also, which may help.

About writing the seller about the Mk II that I posted the picture of, no help. Says it's a rummage sale item he's found and knows nothing about them. I asked for more pictures so maybe he'll return something more to chew on there, or hope someone reading can put a finger on the question.

injunnut1

jetpack ,
You ought to just bid to win that "Wen Mac" engine, they usually go for relatively cheap on eBay? There was a complete write up on all of the various "Wen Mac" engines in the "Engine Collector's Journal" publication a few years back, I do not remember (but then my memory is shot) seeing a tank like the one you pictured, however the blurry photo is sort of hard to decipher. I am still looking for the ducted fan Model Jet Airplane articles, I did find the full size "Cougar" Jet plan so far.

Donald Garry

jetpack

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Already laid down an opening bid, Don! Lets see where it rolls to! Still heard no word or pictures back from the seller though after my first question about it.

Japanman

Hmmm... You could then bore that baby out and pop in the internals of a Fora..... You could satisfy you need for aesthetic period looks and power to spin a fan in an excitable manner

Actually, I wonder if someone like Andy W has done any re-work on these engines? I bet there is a bit more power lurking inside em.
Then again, a cox TD 049 has plenty enough power to fly well with.

S

Beeza

My Feedback: (1)

Hey injunnut1--
I for sure would be interested in the 2 plans you think you can dig out!
Please keep me posted or contact me offline. I'll gladly pay for copying
and shipping costs.

Beeza

jetpack

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I have run Testors versions of these in my control-line building days, and they are simply just flat on power. It just seemed they were always choking for air...must be the exhaust slits not big enough I think. They just ran much quieter and at a lower rpm compared to a Cox. Almost like a really fast steam engine. Also if I remember right they had a larger diameter piston than a cox also, which means they must have had a shorter stroke to them for the same displacement.

I remember running one on the Cox racing fuel as an attempt to get the power up in it, and it cooked the piston in less than five laps. That was with a super rich needle too. I remember looking at the piston after getting it out and admiring the nice rainbow colors it had on it. After that happened I kinda passed on Testors engines when I would see them.

lildiesel

FWIW, Wen Mac Mk. IIs I've seen look a lot rougher than the one a number of posts above. I think it's been lovingly smoothed and polished. Nice tank, too.

The Testors .049 from the late 70s has a very similar look and a nicer finish, so it would be a suitable substitute. It has an encapsulated spring starter that might be easier to work with than the pull cord on the spinner nut. The McCoy Redhead is the same engine with a stylish red anodized glow head.

jetpack

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Hi LilDiesel,

Would you happen to know what the triangular spacer is behind the crankcase? Is that a mount or some type of tank extender? Maybe it was to capture a wire landing gear set?

gcb

My WenMac Mk-II has a shiney finish also.

I believe that Wen Mac invented that spring starter and Testors/McCoy bought the design from them. Perhaps this is the Testors .049 you are talking about. That starter also appeared on the Testors 8000, their last effort.

Beeza

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My Wenmac c/l plane barely flew with so little power.

About plans--I dug around the basement and found a plansheet of the 1/2 duct-fan Sabrejet with a large decal sheet as well. The engine shown inside looks like an OK Cub. There is also a pattern for the fan...adjust the pitch of the blades as needed.

The thing is that I'm missing the 2nd page that has the wing and stab plans. I can find no credits on the plans as to where they came from, but I've prob had them 15 yrs or so. Does any one have the missing 2nd page, so I could get a copy?

Beeza

lildiesel

The triangular spacer appears to be part of the tank assembly since the tubing from the needle valve connects to and a vent tube is visible on it.

injunnut1

I have found the construction articles for the 1/2A Ducted Fan "Douglas B-66 Bomber" (MAN - April, 1957) and also the "Grumman Cougar" (MAN - May, 1956) models. Both designs are Free Flight models and are powered by spring starter equipped Cox "Thermal Hopper .049" engines. I will try to fire up my scanner this week-end and get some quality scans for you guys to work from. Also I will post a few of the photos from the articles here on the forum. My favorite photo from both articles shows the designer / builder (William H. Paxton, Jr.), a Little Kid, and LeRoy Cox gathered around the "B-66 Bomber" model. Both models are shown in full flight ..... the designer / builder says he launches these models via the ROG method only!

Donald Garry

CoosBayLumber

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For the past folks, you need to visit the OKHerkimer web site to find out data on their old glow engines. As had been rumoured around RCU once before, sorry the firm never made an official R/C glow engine. The A/C kit as shown was sold to FOX back in 1960, but only a couple "may" have been made. For they ditched most everything that did not sell in quantity. If you are really into glow powered DF then look up the articles by P.E. Norman of the U.K. and the few by Walt Musciano of the 1970-80s. Both of which seem to be collector's items per the U.K. web forums.

Also in the past, I did up a laser cut replica of the shown Berkeley T-2-J Buckeye kit a few year ago. The kit I had to copy from was complete and new, for I bought it rigt off the shelf a $4.95 but never assembled it. But still had the PSST jet engine inside. This was swapped out with a repro Tellasco design, and is available from their web site. Much news there too as to Jet-X parts, plans, etc.

I flew my repro A/C as per original, and it went OK for maybe three flights, then with a quick breeze it veered off to left and down under power and became a write off 10 seconds after launching. Too much trouble to continue.

For the futurists, I have been doing plans for Kress Jets. Am working on a Tomcat to fit their new EDF 709E unit. Same unit as on their earlier Viggen and Eagle kits. John Kress intends to bring out a Skyray based upon the Berkeley design. The Skyray that Jet Hangar Hobbies is offering was basically an enlarged Berkeley (with a bit of Comet) design as per Larry Wolfe. The new Kress Skyray will be an enlargement of the Berkeley design, such that it fits one of their EDF units. Expect a year for this one to be built.

Wm.

gcb

Wm,
You have me a bit confused. My understanding is that John Kress passed away a couple of months ago after selling "Kress Jets" to someone else some time ago.

In any case, glad to hear that the business is still going.

George

jetpack

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I lost the bid on the wen-mac, it went past my 21 dollar high bid. I think becaues it had the tank and spinner on it made it worth more than I thought. They usually sell for 10-15 dollars from what I've been seeing. I'm still going to keep looking...

jetpack

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I won a Mk II in good condition with a tank and what looks like a string-start pulley which would be a proper way to start these ducted fan dealies - just not correct to print and what I am striving for.

Now it just has to be paid for and shipped, then I can tear it down, clean it and polish it. Is there anything I should be aware of or tricks to taking a Wen-Mac apart?

I won it for $9.99 and was the only bidder. I am charged. What lies next I guess would be to scrounge for a basket case with a good recoil and try and convert this one. I am not sure if removing that recoil is possible. Has anyone tore into one? I think someone said they are rivited ???

proptop

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Sorry to say it, but it looks like the recoil starter is missing...?

The "gap" between the black flywheel / prop drive disc and the I. is where it shoulda been...you can see the alignment pin on the bottom strengthening rib....it would have gone into the back of the stamped steel (usually black) recoil spring housing.

You can see a notch for clearance in the intake venturi just in front of the spray bar.

jetpack

My Feedback: (1)

Well its good to know the case is ready for a recoil, I just have to find one now and try and swap it without destroying it if thats even possible, I am not sure - but the case and the cylinder and head were in such good shape I couldnt pass it up for ten bucks, and it has a tank - most everyone I've come across is missing it.

If that recoil cant be swapped without wrecking it and it has to stay with the case, I'll buy up a plier victim that has a decent case and recoil and swap over the cylinder and tank

proptop

My Feedback: (8)

I forget what they call 'em but they are like a rivet with a spiral (sort of like threads) that pushes in and grips the aluminum. They will pull out with fingernail clippers.

I can't promise ya anything, but if I can find the cookie tin that I have a bunch of misc. and sundry in, I will see if I have any Wen Mac recoil parts in there...(cross your fingers )

jetpack

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Drive rivets. Those dang things. I experienced those on my K/B carbs - almost put an eye out with a dull exacto blade trying to get under one of those to grip it.[sm=pirate.gif] The hardest part about them is just getting it broke loose, after that they pull and spin right out. They don't ever grip the same either after they are removed. It's like a one-shot deal with those. I wouldn't doubt that your looking for them just to get them away from you. [sm=tongue_smile.gif]

proptop

My Feedback: (8)

O.K. I found it...(amazing!)

There is a rear part of the housing, and a recoil spring with the little "thingy" (technical term) that slips over the prop shaft...but I don't recall if that's all of it though?

If you want the parts, PM me...they're yours