R/C Lee

My Feedback: (3)

Thanks for your kind comments. I plan to make a "longer" chin strap, hopefully reaching about 1" more forward. Also plan to make a new engine mount to move the engine an inch or so forward. If that doesn't correct the balance, I'll solder on a sort of platform onto the chin strap and add some weight there. Here are a couple more photos - hope this works. Notice how long the tail moment is. Lee

H5487

Lee,

I can't speak for the original Demoiselle but I believe that the "improved" version that was constructed for the movie had the pilot sitting a little farther forward, perhaps forward of the CG. It looks like your pilot is sitting closer to the trailing edge. Santos Dumont was a short-statured man and he still had to hunch over to fit under the wing because the Demoiselle was a tiny airplane. What this means is that the pilot was a larger percentage of the flying gross weight and, thus, his position about the CG was more critical (much like one of the modern ultralights.) Moving him just a few inches forward might have completely cancelled the lack of any fuselage weight forward of the CG. There's also a chance that the movie version was constructed with a shortened tail.

While this may not help your model balance any better, it would explain how the movie plane was able to fly better than the original (which was supposedly "squirelly").

Harvey

R/C Lee

My Feedback: (3)

Harvey, thanks for the info, and I hadn't thought of that. I didn't want to hear the word "squirelly", though [&o]. The article that accompanied the plans mentioned that their model, which flew in the movie, had a lot of lead added to the front of the plane. After they test flew it, and found out what weight was required, they melted lead into the copper "chin strap" for that forward weight without it showing in the final configuration. One of the photos in the article shows quite a bit of lead wrapped around the chin strap for their test flights. If anyone reading this wants to build one, there's at least one correction to be made to the plans, so let me know. Lee

H5487

Well, of course, now we're all curious about that correction!

Harvey

H5487

The original Demoiselle's tail, with its gimballed mount, has always been considered by historians to be what made the plane so "squirelly".

Harvey

R/C Lee

My Feedback: (3)

The plans identify the wheels as 7-3/4 dia, but the side views of the wheels are 6-3/4". Unfortunately, I took the 7-3/4 label as correct and made up a set that size. Way too big [>:]. Then I measured the plans and made new ones at 6-3/4". I added a 1/4" ply filler piece between the front uprights, with a blind nut so the front wing hold-down bracket is easily screwed on for the front attach point.

Harvey, I put the pilot right where the plans showed, which as they said is where he was in the model used in the movie. In retrospect, since his center of balance is a good 4" behind the cg, I'd move him forward as you mentioned.

For the "gimbaled" tail, I followed the plans. However, it swings around a bit wildly in both elevation and yaw, so there has to be a better way to damp it down some. I just put in a lot of expo for these two surfaces hoping that will work.

I'd also go with something like Nelson's Lite Fab, especially for the tail to keep the weight down. I used Aero Silk which was a little heavy, and needed some clear dope to seal it. Probably added a little too much weight in the tail.

I used some 1/4" spruce for a couple of the main "spars" in both tail surfaces. Doing it again, I'd probably use just balsa and some fishing line for stiffening braces.

Instead of a bellcrank for throttle control, I just used a HiTec 225 servo mounted behind the engine. I put a Saito .30 up front. With the all-up weight and balance problem, I'm going to change it to a 2-stroke .46 located a little forward of the current engine and I'll fly it with judicious use of throttle.

Instead of ply for the elevator/rudder bellcranks, I used 1/16" G10 - much stronger and won't wear as easily. I used Proctor control wire from the bellcranks to the tail. It's not much weight, but I'd probably use the Spiderwire fishing line to reduce the weight.

The wing tip ribs are not strong enough to stay straight when shrinking the wing covering (probably made worse by using Aero Silk). I'd use 1/8 aircraft ply for the tips.

Most of these comments are my preferences to make the model better. However, the key issue is to somehow find a way to move weight forward.

Hope this helps.

Lee

H5487

Sounds like good advice, Lee.

Thanks,

Harvey

RandyL

My Feedback: (4)

I have been flying the little SIG Demo since it first came out and I love it. With that positive background I finally got around to ordering a set of the Randy Charles digital plans a few months ago.

About 2 months of fun figuring and building I am now ready to test fly my second Demoiselle. Thought I would make a post on this thread as I have read it for years and admire the work done by you all.

Mine has pine longrons, cedar braces and uprights, Quadra 35 motor, spring loaded tail skid, Sig Koverall cloth covering with clear Sig Nitrate and Butyrate dope topped off with Daytona White Butyrate dope from Aircraft Spruce co.

140lb Kevlar cord for bracing and controls it weighs in around 15 pounds with nearly 1 pound of lead bolted to the underside of the nose. More pics and info if there is still interest in this thread.

Randy

R/C Lee

My Feedback: (3)

Randy, great job, but a Quadra 35? And, I thought it would be fine to fly mine on a Saito .30 . Clearly, mine is verrrrry tail heavy, and I will probably need a pound or so of lead in the nose. I'm not sure my framework can handle much more than a 2-stroke .45 or so, but I'll try it when I get through with a few other projects. How does yours fly? Did you have any trouble with the flying tail and directional stability? Thanks, Lee

RandyL

My Feedback: (4)

I have yet to fly mine..just finished it Saturday and took it out for a quick picture. To cold and breezy out for a test hop.

I used the Quadra 35 as Randy Charles said his would not even take flight with his original weed trimmer conversion motor ( 25 -30cc ? ). He has given me good advice on what to expect on the test flight. I will post my results when I get a chance to fly it.

Randy

Roux

Hi Lee - very nice - mine is 1/4 scale with 52 fourstroke. Busy rebuilding the fuzz from bamboo.

Regards
Roux

H5487

Looks museum-quality, Roux. Very nice! Might I ask where you got your wire wheels?

Harvey

R/C Lee

My Feedback: (3)

Roux, beautiful job. It looks like you also extended the front "chin strap" a little, and added some weight at the front. Did that and the .52 4-stroke help move the cg forward? Also, how does yours fly? I have heard that they are a little squirrelly. Thanks, Lee

RandyL

My Feedback: (4)

Very nice Roux........... I did get to fly mine. Flew great! CG is set at 25% and I will be moving it back more each flight to test how it flys. Nearly no glide, needs power to land but turns and flys like a trainer....very happy with it!

I think more tail heavy will help with the glide and landing, we will see. It is very stable as it is currently. Left or right turns are sharp as need be. Hope the video link a friend put up works.

Randy


http://www.youtube.com/watch?v=CpEdaPdQi4E

MajorTomski

One other thought Cleveland Models has plans for a 21 inch span blown up to 1/4 scale at 56 inches. BUT they are originally rubber powered plans, you'll have to modify them to RC.

H5487

Randy,

The reason why you need power to land, and why moving the CG aft won't improve the glide, is twofold:

1. The airplane is very draggy. There are lots of flying wires in the breeze and the fuselage and motor couldn't be less streamlined. Santos-Dumont created a cute airplane but not an efficient one!

And 2. Low weight and high drag equals very low momentum. Chop the throttle to idle and the airplane practically screeches to a stop in mid air. It's akin to trying to throw a Kleenex.

Therefore, moving the CG aft isn't going to improve the glide. In fact, what it WILL do is make it much more difficult to recover from a stall/spin. Other than changing the Demoiselle's design, about the only thing that you can do is to love it for what it is and accept that it has some quirks. (Pretty much the way my wife feels about me! )

Harvey

H5487

Nice video, Randy. It looks like it flys nicely! However, I have to admit that I spent the first third of the video bracing myself against a blood splattering from the guy in the baseball hat who strapped in the "pilot" while the engine was running!

Harvey

RandyL

My Feedback: (4)

Harvey, I like your statement about "throwing a Kleenex"... : ) The plans originally had the CG set at 19% and I had about 2 1/2 ponds of lead on the nose. I didn't like the idea so I moved it back to 25% and took a pound of lead off, hoped for the best on the test flight and all was great.

I want to move the CG back a little at a time to see if I can remove any more of that lead on the nose. When the throttle is chopped it goes into more of a nose dive than you can pull out of with full up elevator. Hopefully I can get a lighter nose and more responsive control by adjusting the weight.

Either way, it flys nice and I can make small changes as I go. Is a fun machine no matter. I fly and build a lot of "draggy" things...you are corrrect, it is what it is!

Randy

H5487

It sure looked good in the video!

Harvey

louierc

Congrats on the successful flight Randy. After also reading the thread on the smaller Sig version of this plane, which has the same characteristic of gliding like a brick, I keep coming back to the notion that the wing is mounted with a lot of incidence. Doesn't it look like it flys with a high angle of attack? If so it seems that would explain the glide and the requirement for some power on landing. Louie

RandyL

My Feedback: (4)

I've been flying one of the Sig Demoiselles since the first days they came out as a kit. I also fly their Antoinette, as well as a Wright Flyer and my own one of a kind Longren #5 as is in the Kansas museum of History.

The Sig Demoiselle does indeed need power to fly or land, to chop the power on landing is to crash! I fly it a lot indoor and out, a very favorite model of mine. I used up a couple of GWS motors and finally went with a Fieago brushless, a great upgrade!

Harvey.... I am the one with the ball cap that you speak of. I was actually a foot behind the prop and behind the uprights of the machine. Still close to the prop however, sorry it made you uncomfortable. I have huge respect for props, (unlike some of the guys I fly with). I know it does not show but it is the truth! : ) I don't want to jink myself but out of over 20 years of flying the only prop cut I have had is finger starting a dang .049...I hate them!!!! I move slow and pay attention all I can. Thanks for your concerns and I will try and do even better.

The pilot of the test flight is a very good friend of mine, we fly models and full scale together. He is far more talented than I on test hops so he gets all the pressure...I flew the second flight.

Here is a few shots of some of my draggy's...

Randy

Roux

Thanx - the weels I have made myself, rims are made with1mm veneer and super glue, spokes from 40lb cable, and the tread an o-ring from irrigation pipes. I have extended the front end a bit for CG and added approx 600grams of lead to the frond end. The total weight of the plane approx 2.7kg (5.9pounds).

Will forward video clip of my flight as soon as possible

Note: It does fly like a brickwhith a deadstick - I have fixed the frame but in the meantime I am building the fuz from bamboo like the original.

Regards

Roux

R/C Lee

My Feedback: (3)

Randy, on your large Demoiselle, did you have any problem with RFI using the Quadra? I haven't tried my 26cc gasser yet, but after seeing your video, I think I'll go ahead and install the larger engine. I have my receiver located in the pilot's body, but the throttle servo seems a little close to the engine, being only a few inches behind it. I'll use Sullivan Nyrods, but I'm not sure how much RFI coupling I'll get with the servo proximity. How did you do yours and how did it work out? Thanks, Lee

RandyL

My Feedback: (4)

Lee, I had no problems with RF. Mine has the servo directly behind the motor as well. I too use nyrod to connect the servo to the throttle linkage on the other side of the "firewall".

In the pic you will see the servo behind the motor and to the right of the fuel tank.. I had no glitching at all and I fly on 72 mhz...old school now days!

If you are converting an engine, make sure to use a resistor plug...not a standard spark plug. A non-resistor, or a plug with cracked porcelin will cause huge problems.

I have a pair of converted Ryobi's on a large B-25 and they gave me no problem at all once the plugs were changed to resistor type.

The 1/4 inch wood firewall and nyrod linkage worked perfect on the Demoiselle. Wish you the best...

ARUP

George Marsden built a 1/4 Curtiss Headless Pusher and the plans are available from Doc Pepino (deceased- his wife still handles these(?)) Mr. Marsden put the receiver and batteries in the pilot's body. For my smaller Curtiss I put receiver and switch in torso. 3 servos are under the seat and one in upper wing. The batteries are in a 'crate' I attached to the front (see my Gallery). I lettered the crate to make it look like it is going from one addy to another! The pilot 'slaves' from the controls (just like what Marsden did) and it's pretty good for laughs to watch him 'move' the controls. You could do that w Demoiselle. You might consider using carbon fibre tubes painted to look like bamboo for the longerons. They would be pretty lightweight and very strong. You could 'cheat' the engine (and pilot et al) fwd a little too to help with any c.g. issues. Put clear drinking straws in a wing for antennae run. Incorporate some kind of bungee action into the gear. These airplanes are very draggy and don't glide so a reliable engine is an absolute 'must have'. They are relatively light for wingspan so don't break easily (bonus) My Curtiss cartwheeled once when wind got under a wing (my bad flying, too, but gotta blame something!) It didn't even break a strut that the ailerons are attached! Good luck w your Demoiselle- what a neat model that'll be!