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Old Jan 19, 2010, 02:50 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
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Very interesting...... is the weight of 996 Grams (2.19579 pounds) for the equipment only or is that everything? You said you length is going to be 2.3 meters (7.4 feet) and the wingspan will be somewhere around 6 feet?

There is a person on youtube who has built several different Depron Jets and they have very low takeoff speeds and landings..... the slowest I have seen (very scale like). Is your construction similar to his? http://www.youtube.com/neffwaffe
What are you using for foam?

Good luck on your build.... I will be watching!

Mike
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Old Jan 20, 2010, 04:41 AM
HappyGoLucky
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Germany, BW, Ibach
Joined Dec 2009
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Thanks,

The weight of all non foam/balsa equipment is 722g (excluding y-connectors and prolonging wires, those make around 200g extra). I can't tell you the weight of the whole plane since I haven't put it on a scale yet but I hope it stays below 2KG.

The Neffwaffe Airliners seem to be ultraligh-weight judging by the low landing/take off speeds. My MD80 is a lot heavier due heavier engines/escs and a more solid/overbuild construction using balsa- and plywood for reinforcement as well as 6mm Depron and a solid Foam-Nose. I think I have seen a person building a plane somewhere around here who claimed he's using the same construction methods Neffwaffe used. His Plane only had one thick foampiece in the middle of the fuselage and a couple of bulkheads. So by the transitive property I deduct my construction is not similar to Nefwaffes.

I'm using 3mm EPP for the wing-surfaces and the fuselage-surface. 6mm depron for everything else. I did so because I read that EPP is more easy to bend and more resilient than depron.

The Wingspan is 172cm or 5.58 feet or 67.72 inches. Total length is 245cm or 7.94 feet or 95.28 inches. (Horray for the metric system) I have taken the measurements from the picture in my first post and not altered anything.
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Old Jan 21, 2010, 03:23 AM
HappyGoLucky
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Germany, BW, Ibach
Joined Dec 2009
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Put the nose on and found a old kitchen scale. It says:
current weight: 1475g, final weight will be 1600g max.
thrust with current setup is about 8.8N or 2lbs.





and btw. thats not beer:

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Old Jan 21, 2010, 08:55 AM
Mike Brinker
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SouthEast Michigan
Joined May 2008
537 Posts
3 1/2 pounds is great..... I am wondering about the thrust to weight ratio? If this model weighs 3.5 pounds and your power is creating 2 lbs of thrust, is it underpowered?

The neffwaffee planes use the eflite superliner fan,motor, esc & battery configuration from what he has shared in his videos.

What about strength for the long fuselage? Will you be glassing the fuselage for added strength?

Mike
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Old Jan 21, 2010, 11:32 AM
HappyGoLucky
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Germany, BW, Ibach
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Quote:
is it underpowered?
Well, I hope not. The E-Flite Airliner weights about 100g less then the MD80 while having smaller wings and the E-Flite Power Setup seems not to be much stronger then mine. (couldn't find anywhere how many Newton Thrust the Superairliner has) The Plane does not feel underpowered at 3.5lbs/2lbs in the simulator. It reaches 130km/h in level flight and is able to climb pretty steep. I don't know close that is to reality.
If it is to underpowered to take off I should be able to increase the thrust/weight ratio by just putting stronger batteries in. The motors and the ESCs can take more then the two 1800/25C batteries currently in use provide. Again I'm new to this and my reasoning might be utterly wrong.

Quote:
What about strength for the long fuselage?
The Fuselage is really strong as is. (At least I think so) Lot's of 6mm bulkheads, two 10x10mm balsa beams, three 60x6mm Depron strips at the sides and the bottom and the 3mm EPP-hull make the fuselage pretty stiff. (if you put the backside of the plane on a level table the fuselage will not bend at all)

cheers
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Old Jan 21, 2010, 09:52 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
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I have no reason to think it is underpowered either. I guess the 3.5 pound /2 pound ratio threw me off.

Are you doing anything special with the wing to create more lift? built in forward slats? udercamber in the wing????? just curious.....

Keep up the great work!!!!! Nice flight in the sim by the way.......
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Old Jan 22, 2010, 11:51 AM
HappyGoLucky
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I hope that the wings provide enough lift as is. Adding forward slats or flaps goes way beyond my abilities.

Second Wing is now attached, central section is closed. The part still open is a big hatch to get to the electrics.
I'll probably leave the engines like they are for now because, from what I read here, building housings for them is a science on it's own(Thrustubediameter/faster airflow etc.) and would make the plane harder to fly.

I suppose apart from cosmetic stuff like sanding/painting and the link between the aileron control horns and the servohorns (still waiting on a shipment from GB) the Plane is airworthy. If I get the delivery and the weather's good this weekend I'll give it a try.

cheers
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Old Jan 24, 2010, 03:29 PM
HappyGoLucky
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Germany, BW, Ibach
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No shipment from England but lots of trouble.

First I realized that the Plane is to large to get it out of the shop. There are two doors directly behind each other and the second door is slightly to the right. The ceiling there is very low.



I could however, get it upstairs, thru a narrow hallway and into the Hay-Room. The Double-Doors there are large enough to carry the Model thru them.

After a half hour Walk thru the Snow I then realized that the plane did not fit into the car. One hour and some detached non-detachable-parts later I could make it fit by bending the wings about 20cm upwards and putting the nose out of the codrivers window.



Was a rather cold drive home. Now I have to solder the antennawire back on and repair what has been damaged. Not much work thou.

cheers
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Old Jan 24, 2010, 03:36 PM
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Nevada, USA
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Looks big! Servo horn's are easy to make, just cut them out of old credit/gift cards.

Is that Sweden?
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Old Jan 25, 2010, 05:21 AM
HappyGoLucky
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Germany, BW, Ibach
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No it's in the "Black Forrest" close to the "Feldberg" in the south of Germany. On a clear day you can spot the Northface of the Matterhorn, the Mont blanc etc. from there.

Maybe you know the Black Forrest Cherry Cake.

cheers

ps: the outside:
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Old Jan 25, 2010, 06:32 AM
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Sukumo, Japan
Joined Jul 2008
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I'm also watching this build. Your attention to detail is great! I have done one scratch-build so far, a Cessna Citation V which is unfortunately too heavy and underpowered to fly. I'm hoping these forums will help me wrap my head around what I need to do to get it in the air. I'm looking forward to seeing your MD 80's maiden on video!
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Old Jan 27, 2010, 02:42 AM
HappyGoLucky
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Germany, BW, Ibach
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Burned a Servo. I don't know how that happend. One of the big Servos in the Wingbox turned 180 degrees to the right when I pluged the battery in and refused to react to tx-commands. I removed the screws and discovered that the plastic on the bottom of the servo was molten. Strange (at least to me). I took a 15year old Graupner servo out of a little ship I build when I was a Kid and, although a little heavy, that servo worked perfectly as replacement.
  • I soldered the Antennawire back to the receiver and that was quite messy. Maybe that killed the servo?
  • Could plugging the servowires into the receiver the wrong way burn a servo?
  • I'm not 100% sure that the Antenna-Wire is realy connected to the connector on the receiver. How can I check? What would be the maximal distance the receiver would still get a signal if the antenna was not connected.

Since the shipment from GB still has not crossed the channel I made my own servocontrolhorns and beefed them up with plywood (thanks capt). I'm now waiting for a totaly calm day to make the maidenflight.

I got a couple of general questions to though:

EDFs/Motors:
The vendor said that the EDFs I bought would have 840g of thrust but I meassured just short of 500g. Batteries are 25C, 11.1V. ESC can handle more then 60A.
It also says 11.1V, 45A, 840W. How is that possible? (As far as I remember from school Watt=Ampere x Volt which means that the motor could only do 11.1x45=500 Watt.)

Timing on ESCs:
I think the Motors in the EDFs are outrunners (the shell turnes when the motor turns). Where do I get the number of "Poles" the Motor has? Do I have to change the Timing on the ESCs to Outrunner? (The standardsetting is inrunner) Is there a risk to ruin the esc/motors if I use a wrong setting?

thanks for your time and help
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Old Jan 27, 2010, 03:18 AM
Go FASST or go home...
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Quote:
Originally Posted by chochmah View Post
I got a couple of general questions to though:

EDFs/Motors:
The vendor said that the EDFs I bought would have 840g of thrust but I meassured just short of 500g. Batteries are 25C, 11.1V. ESC can handle more then 60A.
It also says 11.1V, 45A, 840W. How is that possible? (As far as I remember from school Watt=Ampere x Volt which means that the motor could only do 11.1x45=500 Watt.)
Welcome to the world of vendors and salesmen...
Don´t trust all vendors, try to find test data done by members on these forums. Most fans and motor combos has been tested by someone here. Use the search functions and you will find it!
I never trust any wendor on this matter. Either the thrust is overestimated or the amp draw is underrated - or both. Confusing? Yes it is unfortunately...

Ben_E
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Old Jan 27, 2010, 05:19 AM
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Canada, ON, Mississauga
Joined Feb 2006
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You have very nice build going o here, your ambition of making MD80 is your driving force, keep it up. I'm subscribing to this thread as i can see you will be a winner with this model.....

What designing program are you using to design this model and then to make parts, i like to try this out myself as i'm very eager and enthusiastic about building nice big scale model of Boeing B767-200 in Air Canada's delivery colors replicating C-GAUN aka Gimily Glider...

See if you can do some modifications to your design and make wing removable from fuselage as one unit like Eflite's B777 airliner or both wings as plug into fuselage sides for east transportation.


Sam
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Old Jan 27, 2010, 10:57 AM
HappyGoLucky
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Germany, BW, Ibach
Joined Dec 2009
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@Ben_E: Thanks. I consider that downright fraud. I did not expect to find directly contradictory statements like the Watt/Ampere/Volt-Thing so I did not check when I bought it.

@Concordefan: Thanks, I used Google SketchUp but can not recommend it. You can't draw splines and a lot of stuff you would expect to be there like automatic measuring is missing. (Maybe it's me) Next time I will use a real CAD-program. Although as long as you just want to build Foamys without complex curved surfaces it's probably a good choice because it's very intuitive.
Please Notify me when you start your Gimily Glider. Are you going to build it with or without engines?

ps. ready for take off:
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