geezeraviation

My Feedback: (3)

Im sure that would help to shore it up but I wont make a hole in a carbon spar, too risky for me. Could end up in playing pick up sticks, if you get my drift.
Doc

abufletcher

How about making a bracket that goes around the CF tube. It could be made of a section of brass tubing, with another length of small diameter brass tubing silver soldered at 90 degrees. The wire attachment bolt would pass through the small diameter tube.

geezeraviation

My Feedback: (3)

Something like that is what I would do. Prolly a strap around the spar, pinched together at the top and a bolt through the flange with a shackle holding the wire. The shackles arent hard to make using wire formed in a U shape with eyes formed on the ends Arup did some on his glider project.

LesUyeda

I do NOT envy you the challenge of covering that undercambred wing. Been there, done that. It ain't fun. Easier with silk and dope, than heat shrinks.

Les

Nieuport nut

My Feedback: (10)

I think you are on the right track; keep thinking about making up for the hole. It's kind of like removing top and bottom flanges from a spar! (Not completely but you get the idea.)

Martin

R/C Art

My Feedback: (38)

Flying Fox, I think the dowel plug inside is sufficient reenforcement for the tube. I mounted a tail skid on a 1/3 scale pup with a carbon fiber tube and the pivot point for the skid was reenforced with a wooden plug - worked fine.

To be sure, take a small length of the tubing you are using and drill a hole into it and see how much it force it takes before if fails.......do this with and without the wooden plug.
This test will ease your mind. By the way, I am enjoying your build.

I concur with the metal gears, but I doubt you need as big a servo as you think. I flew a third scale Eindecker with wing warping for several years. I used 100 oz/in servos, two of them, each one pulling just one direction because I couldn't figure out how to push the cable (hahah, that's a joke son). I could have hooked one servo to the belcrank that warped the wing, but at the time thought I needed two. In retrospect, one would have sufficed. If it seems to take a lot of servo to warp your wing, then you have built your wing too strong......remember, the cables are supporting the wings, not the internal structure of the wing.

Flying Fox

I am an old school dope dude, it's a great technique and works really well but it's been many years since I've used the technique. Plus I don't think I could stand the fumes anymore. I do however prefer fabric over plastic covering, especially on a scale WWI subject so I will be going the alternative to dope method of using heat shrink fabric covering and Polycrylic (check out the very informative posts by Tmoth (Jim Suchy) over at RCScaleBuilder.com). As for covering the undercambered ribs - another 1st for me, I'll be sure to use some Stixit or Balsarite so the fabric adheres to the undercambered rib caps, and I won't stretch too tightly.

After all your input and good ideas/suggestions I'm rethinking the 'piercing the carbon fibre tube' dilema. Some testing shows it would be okay on the main spar if the dowel plug is used for reinforcement. However the rear spar is a 1/4 x 1/8 hollow rectangular carbon fiber rod and there is no way it can be piereced without compromising it. I will have to use an offset bracket here at least.

Currently working up some offset bracket ideas which I will post soon but in the meantime I'd appreciate your opinions on the following point:
- it would be a whole lot easier to permanently mount the cable brackets to the spar and use a clevis as the cable detachment devise. My worry is how reliable/safe/structurally sound and easy to use are clevises (with a retainer obviously). If a clevis fails in flight it's all over. Look at my drawing and let me know what you think please. I am also considering using a fork-end like retainer in which you screw a bolt through to retain the cable loop (instead of a clevis)

What do you think?
Brian

Flying Fox

Thanks for all the ideas and advice guys.Here is a design for the cable attaching offset bracket for the main spar. Very close to scale. A 6-32 allen bolt is used to attach/detach the cable system allowing wing removable for transport. Structural integrity relies on the brass bracket and bolt - it would be very secure (my soldering skills are okay). A similar method would be used for the rectangular rear spar. This would involve 16 allen bolts to attach/detach the wing each time: 4top 4 bottom x2wings - not bad at all for a scale WWI airplane.

I would prefer a locknut instead of a simple brass nut (could a bolt vibrate loose during a flight with a simple brass nut?) but if I solder a locknut to the brass tube would the heat not melt the flexi-stuff inside the locknut?

Stopping by the hobby shop for parts today.
Cheers,
Brian

LesUyeda

"using heat shrink fabric"

I have been known to place cardboard "shields" over the areas that I did not want the heat to release the fabric.

Les

ARUP

The 'N' has battens to hold the fabric- right? Undercamber covering will always stay in place with those. I have a Bleriot XI with wing warping and the fabric is still attached after 7 years! I put the fabric on the bias. I used Koverall and Stix-It only, no battens. For the cables anchors just drill marine ply to fit the CF spars and slow cure epoxy in place. Then you can drill and tap or put threaded inserts for bolts. My $0.02. Neat airplane!

Ooops! edit:- off set ply brackets to make sure bolts and respective holes don't go thru spars.

abufletcher

When modeling solutions start to get complicated, that's when I try to go back to the original and ask: "How did they do it?" As often as not, that ends up providing the answer.

Flying Fox

Yes Arup - the "N" does have cane battens on the wing ribs to hold the fabric down. I will use them so they will help hold the fabric on once applied, but either way I'll use something to help adhere the fabric to the undercambered ribs as i apply the fabric.

I will have to think of some way to make the cane battens. Hmmm, maybe I'll try splitting some bamboo skewers?

Nice to hear you have a seven year old Bleriot XI model with wingwarping, right on! I'm curious as to how it flies with the wing warping method. I know many modelers who make 'wingwarpers' often put on ailerons instead. Hopefully it is mainly to avoid building a functioning wing warping mechanism and not to alleviate flying characteristics of wing warpers.

Thanks for the input - lets see a photo of your Bleriot.
Cheers,
Brian

abufletcher

It's probably best to think of wing-warpers as "3-channel" models...with a bit of "assistance" from the warping. I spoke with the pilot of a full-scale Bleriot and he showed up how little the wing actually warped (about an inch either way).

Flying Fox

I've heard that one way to prep for flying a model with wing warping is to switch out the ailerons and rudder - put the rudder on the right-hand stick, ailerons left side. This way you get use to the 'feel' of relying mostly on the rudder for lateral control. Others have said its just well co-ordinated aileron-rudder flying?
Maybe several wing-warp flyers can chime in with their opinions. Arup?

Flying Fox

This is so very true, isn’t it? I could do this with the main spar by inserting a dowel plug to strengthen the carbon rod but I can’t pierce the thin carbon fiber rear spar. Some basic modification is necessary - and after I get over my initial frustration I try to follow the KISS protocol: Keep it Simple & Scale!
This is what I had in mind and I’ve worked out two solutions. The first was a work-up of the brass fittings I designed. Each fitting requires two 6-32 bolts - one each for upper & lower cables at each attachment point. You can see from the photo that they would work just fine if I had thought of this before building the wing![:@] Major surgery would be needed to make this work now.

I created another cable mounting bracket using hardwood blocks with offset tabs. Each tab was predrilled and a 6-32 threaded aluminum insert nut was screwed and glued into place. I picked up these aluminum insert nuts at the local hardware store. After inserting them into the hardwood blocks you screw them down with a special nut which collapses the aluminum insert nut, locking it in place. They were a little fiddly to get to work properly but I got the hang of it. They are also glued in place with light CA.

Each cable mounting bracket slides over the spar, which was lightly scuffed up, and slow cure epoxy holds them in place. You’ll notice I had to cut away the balsa facings from the main spar and also that I had to carefully cut each of the front brackets in half so they could slip over the tubular main spar. I will likely cap the seams with a thin veneer of plywood. The rear brackets are similar and slip over the rectangular spar.

All brackets are mounted in scale positions. I noticed some errors on several of the 3-views so I have relied on a photo of a downed Morane Saulnier Type-N that nicely shows the positions of all the brackets, both topside and underside of the wings – thanks to the ever efficient German military. The photo is from “Morane-Saulnier Types N,I,V" by J.M. Bruce, Windsock Datafile 58.

Tonight, now that the epoxy has had 24hours to cure, I will test the wing warping system with a high-torque servo in a scale position. All the parts for the left wing are cut out, shaped, sanded, and ready to go for the left wing so I will get on to that quickly.

Thanks to all of you for following along, I appreciate all the support!
Cheers,
Brian
Photo 1 – brass cable mounting bracket worked up from design
Brass wing Cable Fitting

Photos 2-3-4-5 Mainspar hardwood cable mounting bracket with offset tabs, and aluminum insert screws for 6-32 hex head bolts
Wingwarp fitting mainspar frontview
Wingwarp fitting mainspar profileview
Wingwarp fitting mainspar sideview
Wingwarp fitting mainspar closeup

Photos 6-7 Rearspar hardwood cable mounting bracket with offset tabs, and aluminum insert screws for 6-32 hex head bolts
Wingwarp fitting rearspar
Wingwarp fitting rearspar closeup

Photos 8-9-10 Right wing showing scale positions of all hardwood cable mounting brackets
Wingwarp fittings fullwing
Wingwarp fittings wingtip
Downed MS-N wing cable connection locations

Nieuport nut

My Feedback: (10)

For battens, you could use a drawplate to take say, 1/4 sq. basswood to 1/4" round and then add a movable cross plate to the hole and gradually reduce the strip to a semi-circular cross section.

Martin

Flying Fox

Neat idea Martin, you must be a woodworker!
So you draw/pull the 1/4" square piece through the drawplate, shaving off a little wood at a time, pulling it through progressively smaller diameter holes, gradually rounding it and reducing it until you have the desired diameter. Then a cross plate like blade to reduce it to a semi-circular section. Okay, I looked it up and understand now.
Maybe I could skip some of the steps and simply reduce a bamboo skewer or dowel down to the semi-circular shape. I'll have to pay a visit to Lee Valley Tools (online) to check one out.
Thanks,
Brian

Nieuport nut

My Feedback: (10)

Hi Brian:

You've got the idea. I suggested basswood because it's light, easily machined, readily available and glues well. I would guess that the original battens would be somewhere around 1" across, (N.11 photos). 1/4" bamboo will be hard to find!

Martin

Flying Fox

Things have been on hold for a while now with work and family obligations... but now I have some time to get back to the build.

The cable attachments issue with the wing spars was solved as mentioned/shown in a prior post so I am moving on to the front end of the fuselage - particularly the cowl-engine-firewall section.

The structure of this area needs to be strong enough to support the stresses imparted by the engine. With a very short nose the MS-N will likely need some lead weight up front to balance the plane, hopefully I can keep the tail end very light weight. Flight batteries, servos, etc. will be located as far forward as possible, and the fuel tank will be over the center of gravity. I’d like the entire engine-fuel tank system to be removable for servicing – the last thing I want is a fuel tank buried so deep in structure that it cannot be removed without surgery. I’ve had a fuel clunk line come off in the tank before and it was brutal trying to diagnose the issue and then removing the tank. So with this one the cowl will come off followed by the engine-fuel tank system.

For power the MS-N will use a Saito 150 four-stroke swinging an 18 inch prop. Yes it may be a little overpowered but I would rather throttle down knowing there are extra rpms when/if needed. It seems like a lot of the ¼ and 1/3 scale planes we see being developed on the various RC forums are designed with ample power as evidenced by their very short takeoff runs in the videos. I’m hoping to come in with a final goal weight of about 15-18 lbs. but at this point it is purely speculative…

Cowl ring, A-former, engine mount former, B-firewall former, and C-former were all cut out of aircraft grade plywood, sanded, and various holes drilled out and blind T-nuts inserted where needed.

Photo 1 – Cowl with cowl ring, and front former A showing blind T-nuts
Photo 2,3 – Cowl front and back showing attachment to former A with socket head screws and blind T-nuts
Photo 4 – former A with blind nuts, B-firewall, C-former
Photo 5,6 – front and side views of Saito 150 Black Knight four-stroke engine bolted to engine mount former and in turn bolted to B-firewall former

That’s it for now. Tomorrow I will dry fit all these formers, carefully align them and glue all together. I’ll post again to show how this turns out.

Cheers,
Brian

LesUyeda

The engine REALLY wants to be mounted horizonatlly, so that nothing shows out the top, to destroy the sillouette (sp).

Les

Flying Fox

Thanks Les, yes it REALLY does, and that is the case but it fits vertically mounted! I chose the cowl size and scale of the plane to fit around the engine. When I firsat measured I knew it was going to be close but figured it would fit with just a few millinmetres clearance and I think it has paid off.


The three formers were predrilled to accept 5/16 diameter dowels. The dowels had to be sanded slightly on the belt sander and then inserted into the formers. The assembly was squared up and glued with CA, carefully measuring as each former was glued to keep things square. All glue joints will be gone over with a little epoxy just to further secure the joint.

The cowl is not yet fastened to its wooden cowl ring as I want to be able to adjust it for prop clearance as I have about a 1.5 degree right thrust built in to the motor mount.

The Saito 150 is mounted vertically, totally concealed under the aluminum/steel cowl, and a scale access hatch on the left side of the nose will provide access to the needle valve, receiver switch, and probably a fueling dot as well. Also by removing the cowl (6 bolts) and 6 bolts on the firewall, the entire engine and fuel tank are removable for servicing!

All up weight of this nose assembly is 4 lbs. 4 oz. leaving 11-14 lbs for the rest of the airframe, fuel tank, radio gear, servos, and any scale detailing including a pilot figure.

Photos 1-2-3 front, side, and oblique views of the nose assembly showing the fully enclosed/concealed, removable Saito engine.

That’s it for tonight

Teus

Very neat and beautiful engine installation Brian,

Q; Can you get enough cooling air over the engine with that very big spinner up front?

Teus

LesUyeda

Beautiful. I love it. Nice, clean installation. Now all you have to do is get rid of that NASTY Master Airscrew labeling:-)))))))))))))))))

Les

Flying Fox

Thanks Teus and Les!

-patience Les, patience

The French referred to this honkin’ big beautiful spinner as ‘la casserole’ or saucepan (lol) and it may very well prove to be my Achilles’ heal in this build. I really don’t know if there will be enough air flow over it to cool the engine. There is some clearance between the spinner and the cowl, a small gap of about 1cm at ¼ scale and that may allow enough air to pass through. Might have to install a channel or baffle to direct air to the cylinder. To compound matters I intend to add a dummy Le Rhone rotary engine that will further impede airflow. I will make a spinner for static display but considering that a functional spinner will rotate with the engine at a max rpm of 9000 or so I am very leery of using one for flying. If not balanced exactly it could prove to be a dangerous projectile.

I could certainly use some help and advice here with ‘le casserole’.
If I have an aluminum back plate machined and then use lightweight fiberglass for the spinner and carefully balance it would it be safe? Or should the spinner itself and back plate be machined out of aluminum for strength, machined tolerances/consistency, etc.? I really don’t know what to do.

I’ve read that often the spinner was removed from the airframe because of engine cooling problems – so I could simply use that as my justification for leaving out the spinner.

What do you think?

abufletcher

I would expect that that 1cm gap (all around) would be enough in terms of air INFLOW. The trick might be making sure you've got 2-3 times as much OUTFLOW so that a pressure differential PULLS air across the cylinder. And yes you'll probably have to install some baffles so that you air from the bottom of the gap also makes it up to the top.