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Sikorsky Ilya Muromets CG

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Sikorsky Ilya Muromets CG

Old 02-15-2016, 01:11 PM
  #126  
Sal C.
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Hi All

I have the wings mounted and just about all the wires installed. There are around 200 turnbuckles. I think I have just four more wires to install
between the upper center section and the fuselage. I still have the large fuel tanks to mount, bomb rack to build, internal flooring to install, windows and window frames to install, plus some touch up painting and the sliding side door and engineer doors (triangle shape) doors for access onto the lower wing.
I dont want to see another turnbuckle for a long, long time. From now on its profile electric foamies for me!!!!

Here's a few more photos.
Cheers, Sal
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Old 02-16-2016, 08:30 AM
  #127  
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Absolutely fantastic!
Old 02-26-2016, 06:56 AM
  #128  
Sal C.
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Hello All

Well, here she is at the WRAM show in the Meadowlands, New Jersey on 25 Feb, 2016. 16 months of work to honor one of the great minds in aviation of the 20th century, Igor ivanovichSikorsky.

Thanks for all the interest.

CHeers, Sal
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Old 02-26-2016, 11:12 AM
  #129  
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Hi Sal,

she looks absolutely fantastic! That's an outstanding achievement and I hope the model will get the attention it deserves.

For me, it's breathtaking to see and I only feel the burning question: Where is the C/G?

Burkhard
Old 02-26-2016, 12:17 PM
  #130  
Sal C.
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Burkhard

Wo bist du gewesen, mein freund?

I have added a bit of lead to the nose of the aircraft under the deperdussin control column and on the leading edges of the wings, especially by the motor mounts. The current balance is around two inches forward of the trailing edge. I may add some more weight. I have plenty of time as I wont be flying it till the warmer weather, April or May timeframe. Of course it will be a very, very calm day.
Good to hear from you, Sal
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Old 02-26-2016, 02:16 PM
  #131  
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Sal, I was always here, just nothing to contribute and Dick said things better than I could.

Just looked over former posts and found #76 where I estimated the neutral point to be at the wing's trailing edge. Since the balance is already ahead of it, you now have a pitch-stable airplane, which would be even flyable if it were unstable. Static stability margin might be 8% now - not too bad. So I wouldn't add more weight but rather keep wing loading low.

Burkhard

Last edited by UStik; 02-28-2016 at 06:53 AM.
Old 02-29-2016, 08:39 AM
  #132  
Sal C.
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Hello Burkhard..

I will be extra careful when I attemt the first flight. Taxi testing, maybe a brief hop or two two become familiar with
its behavior.
Thanks for all your assistance.

Cheers, Sal
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Old 02-29-2016, 09:03 AM
  #133  
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Best in show! Congratulations to this appreciation, it's well deserved!
Old 03-01-2016, 09:06 AM
  #134  
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Hi Sal, hard to believe that it's more than half a year since we discussed the IM design. Your accomplishment prompted me to revisit it in the simulator.

Now pitch-stable with 8.3% static stability margin, still at 45 lbs weight (is that correct?), there's no pitch-up or tuck under, just stable behavior. That means level flight at half throttle (at 25 mph, as before), climb at full power (at 23 mph), glide at little power (at 23 mph, touch-down at 19 mph) - provided the "correct" decalage is found. The stable version needed 2 degrees less than the unstable one. That remains the biggest problem for the maiden flight. Should be solvable though...

The model needs power in turns, and much top aileron. Vicious stall is still the biggest threat, even though there's less danger to get into one unintentionally. Just don't climb and turn at the same time.

Burkhard

Last edited by UStik; 03-01-2016 at 09:14 AM.
Old 03-01-2016, 11:26 AM
  #135  
Sal C.
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Hello Burkhard..

Yes, weight at 45 pounds. In the coming weeks, I will get exact numbers on weight and CG. I need to take a break to clean up the mess in my building room. I want to get organized, then back at it.
I am encouraged that the numbers look good and that stable flight is possible. Anyway, I may have more exciting news about the Muromets in the coming weeks.
This has been a rewarding build and the model is catching some influential eyes.

Sal
Old 03-11-2016, 07:38 AM
  #136  
Sal C.
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Hello Burkhard

Here's a bit of news. I received a phone call from the Sikorsky Corp last week. They have invited me and the Ilya Muromets to Sikorsky Family Day in the fall. I was told that Igor's sons attend the event and would like to see the model. I am so thrilled!
When I started this project, I contacted the Sikorsky museum to inquire about documentation. They had very little from his time in Russia but asked me to send them photos from time to time. I sent them some finished photos a couple weeks ago and they passed them onto Sergei, Igor's oldest son.
Now I have to decide, fly or not fly? I certainly dont want to damage it before I bring it to the Sikorskys'.

Sal
Old 03-11-2016, 09:39 AM
  #137  
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It's an honor for you to be invited to display the model at the Sikorsky Family Day, and deservedly so. On the other hand, you have honored Igor Sikorsky by building such a beautiful model of his long ago creation. I congratulate you for not only your painstaking craftsmanship, but also for the happiness and pride that you will bring to his family and the Sikorsky employees.

To fly or not to fly ? That's a question that you'll have to agonize over for the next few months. Heck, I'd be agonizing even without the invitation to display. Maybe a compromise would be to show it unflown this year with a return invite next year complete with flight videos.

Regarding ballast in the nose or any other means of increasing the margin of safety for initial test flights: I try not to focus too much on having the airplane in a perfect configuration for the first flight. Any cheating I can do to make sure a plane is stable for the initial flight is fair game to me. I see the first flight of a plane as a work in progress rather than a grand coming-out party. Notice in the pictures below that I added temporary "enlargements" to the horizontal and vertical just to be sure. My calculations weren't all that exact due to the biplane configuration and also due to the really fat fuselage. Over the course of several flights I incrementally reduced the size of the enlargements until I was comfortable with the scale empennage and the CG location. The white enlargements just slipped over the tail surfaces and held in place with tape.

Dick
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Old 03-11-2016, 09:50 AM
  #138  
Sal C.
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Hi Dick

Thanks again for the kind words. Your Grumman looks great. First flights always get the heart pumping.
Maybe I will wait till after visiting Sikorsky. Heaven knows, I have so many projects to keep me busy.
Thanks again for all the inspiration.

Cheers, Sal
Old 03-13-2016, 10:26 AM
  #139  
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Hi Sal,

again great news, again congratulations also from my side, and again Dick found better words than I would ever be able to find so I just wholeheartedly agree.

The word agonize struck me because that's what came to my mind as well, just in German. I think we're agonizing with you without being able to bear at least part of the burden. Still our different (and unburdened) views might help for a decision what to do.

I think I wrote the model chose you to be built, and now I would add to be flown. And my impression from your posts here is that you just had to build it (you wrote that explicitely) and that you just have to fly it. A small model would be the right way to minimize risk, but in another sense it could be avoidance (as well as your other projects). So I'd think the model should be flown as soon as possible, even if with all necessary precautions, just to reward you for your hard work and remove the strain.

I can't see any reason why the probability of a crash should be bigger than with your other models. On the contrary, this model should be easier to fly due to its size and sluggishness. You could even prepare for its special traits with a smaller model or the simulator. It's just that a crash would be appalling because the model is so valuable and the risk seems big. But ... you're not only a great builder (and pilot) but also a great repairer.

Even if you take your time and carefully prepare for the maiden flight in spring, a crash in summer would leave enough time to repair till the display in fall. And I think a successful maiden and even following flights are far more likely than a crash. You could take Dick's advices to make the maiden flight uneventful. But you dont even need more nose weight or tail enlargements because your model has them already - per design.

If I look at me, it would be first and foremost a mental problem to fly this model. Everything that makes me confident would help, like having considered every possible technical problem and being prepared for all imaginable events during flight. That's why I'm pondering so much and why I'm using the simulator, and that made the maiden flights of my models uneventful just because my heart was working low-key so I made no mistakes.

Of course I don't know how it's for you, I can only say that in your stead I would not make the maiden flight conditional on the Sikorsky display because that would prevent it. I think you can have both, but only (mentally) independent from each other. You can take your chances, which are good. That's just what came to my mind over the weekend...

All the best,
Burkhard
Old 03-18-2016, 09:25 AM
  #140  
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A well deserved win. The Muromets looks absolutely fantastic.

After the last round of "did you make a little test glider yet?" I was just about to make one of my own. But a squirrel with something shiny in its jaws ran by and I was off and running in another direction.

Perhaps we need to make it a race to see who can make one first!
Old 03-18-2016, 10:48 AM
  #141  
Sal C.
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B, Burkhard, Dick

I am off to the largest RC Trade show in the country March 30, the Toledo show. I will take the Muromets and educate the masses once again. Plus, I get to meet up with old friends and enjoy the show.
When the weather warms a bit, I will double check the CG and overall weight with the 6S packs installed.
May make a little toss glider too.

Cheers, Sal
Old 09-12-2016, 05:33 AM
  #142  
Sal C.
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Hi Burkhard, Dick

I know that it has been a long time since I finished the model. I have been very busy with family and work. I decided to take the Ilya Muromets to the Old Rhinebeck Aerodrome to celebrate the 50th anniversary of the Rhinebeck Jamboree. Modelers came from Florida, Canada and the Midwest to attend. I wanted to taxi and maybe get a little air under the tires. Check out the results.
Cheers, Sal

https://youtu.be/qLZpc70v09M

http://https://www.facebook.com/bals...2035389248837/

https://www.dropbox.com/s/08v9sg0tbh...omets.avi?dl=0
Old 09-12-2016, 07:47 AM
  #143  
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Congratulations, Sal, on bringing to fruition a most challenging and complex project. It's even more beautiful now in flight.

A couple of observations: First, it sounded like you throttled back a bit very soon after takeoff. Must have plenty of power. Second, the stability in pitch looked excellent. Did you adjust the sink rate on landing solely by throttle, or were you using elevator inputs as well ?

Last question: The wings seemed to stay nice and level throughout the flight. I think I could see some aileron deflection at one point, but not sure. Do you remember using any aileron input ? If you did, then there didn't seem to be much if any yaw induced by the aileron input.

Again, a job well done.

Dick
Old 09-12-2016, 07:57 AM
  #144  
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Sal, Congrats and a job well done !!!

I chatted with you at Toledo and was very excited to see your post. What an amazing project and it's very cool to see air below her wings.

Keep up the great work as there are many of us out here lurking and enjoying your success !!

Thanks for the video !!

Joe

Last edited by Joespeeder; 09-12-2016 at 12:05 PM.
Old 09-12-2016, 08:33 AM
  #145  
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Hi Sal, that is truly amazing, congratulations! I don't know how you felt, but at least for me it would be an immense pressure to finally maiden this model. Now it turns out to be a quite manageable flyer, or at least it looks so. My impression from the videos is that the aerodrome is not really suited to bombers, as it were, and that you just got the model back to earth to avoid having to fly turns. With more room, you wouldn't have had to throttle back as much as you did and could have even done a greaser landing. But it looks that the model would be perfectly manageable on a less confined field. A very encouraging maiden flight!
Burkhard
Old 09-12-2016, 11:39 AM
  #146  
Sal C.
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Thank you All

Burkhard and Dick, thank you again for all your assistance and interest. It was your many postings that helped me realize the first flight.
It is such an unconventional aircraft, I still cant believe that it flew.
I did throttle back after takeoff because the model was climbing, even with only 1/4 throttle and I did not want to make a circuit. As it was, the model flew for a distance of around 1000 feet or more. I do believe that it is overpowered, which is not a problem, just an observation. It did not require any trim changes for the flight. I mostly used throttle management to bring the aircraft down but I did use a bit of down elevator to help it along.
My observation is that it is very stable. However, my next flight will incorporate turns to see how effective are the rudders and ailerons.
So, standby for more reporting.
I am ecstatic over the first flight. The model wanted to fly, I could feel it on the sticks. Even on the ground, ground handling was easy with
rudder turns. To sum up, It was historic!

Sal

Last edited by Sal C.; 09-12-2016 at 12:04 PM.
Old 09-13-2016, 06:04 AM
  #147  
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Sal, Simply an amazing accomplishmen for you. So happy to see the transformation from plans to reality as you have made a most challenging model into a flying aircraft!

well done!
Old 09-23-2016, 05:39 AM
  #148  
Sal C.
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Burkhard, Dick and all

Here's a link to the flight of the Ilya Muromets taken on 9/21/16. Flight time was 5 minutes 30 seconds, I made 7 circuits before landing. Plane weighs around 50 pounds. Four AXI 4130/20 motors, Jeti 77 opto advance controllers, using Floureon 6S 4500mah packs, swinging 16x8 XOAR scimitar props. I took one battery out after flight, not even warm. I put it on my Cellpro 10X charger and it said I still had 75 percent charge.
I could probably fly for 15 minutes. The only "electric " issue I had was that the Jeti 77s were factory set for medium brake and I tried to remove so the props would free spin. I was unsuccessful.
No rudder or aileron trim necessary, however, I had to put lots of down elevator trim. Very stable, turns great on rudder and ailerons did not yaw the model. I may add a little more weight up front, add downthrust to the motors and program down trim with throttle.

Overall simply amazing. It even flys nose down in level flight just like the full-size.
One of the landing gear failed and will need to be redesigned. Like the fullsize, they are too weak. I will have it fixed shortly.
www.youtube.com/watch?v=I-3_cXuiNQM&feature=youtu.be

Cheers, Sal
Old 09-23-2016, 05:42 AM
  #149  
Sal C.
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Hi Again..

Here are some photos from the 9/21 flight.
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Old 09-23-2016, 07:31 AM
  #150  
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Sal, the single word that comes to mind with seeing the video is MAGNIFICENT !

As you well know, designing and building a model from scratch involves a lot of decisions and problem solving along the way. It looks to me like you got it 99.9% right the first time. That's a remarkable show of good judgement and solid problem solving skills. Now, with a bit of landing gear work you should be ready to show 'em at any meet where the best of the best come together.

In your post #148 you mentioned programming a bit of elevator trim to be mixed in with throttle. I have done that on a couple of models and found it to make for a nicer handling airplane. But I have also found that I needed to program some delay into the elevator trim movement. In my case, elevator trim change was largely a function of airspeed, and airspeed doesn't immediately change when you move the throttle. The airspeed lagged the throttle movement by a bit, so the trim change need to lag by a similar amount. Your mileage may vary, as your trim change may be the result of prop blast over the wing and empennage rather than due to overall airspeed change. The Ilya Muromets does appear to be sort of a "one speed" airplane.

I don't know what brand transmitter you are using, or whether you have played with a delayed mix function. The objective is to have the trim change wash in slowly after throttle movement. In my case (Airtronics SD-10G), no matter how fast I move the throttle, the mixed elevator trim takes about 5 seconds to fully come in. If you can implement this function in your transmitter, starting with a very long delay seems to be harmless.

Dick

Last edited by otrcman; 09-23-2016 at 07:39 AM.

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