Flat plate wing thing
08-15-2009, 05:41 PM
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Flat plate wing thing
I was working on a high aspect ratio flying wing with electric in mind but the short cord was giving me fits fitting the gear into a narrow area. After looking at pictures of a X-48B I came up with an idea of half delta and half flying wing. This would allow me to do every thing I wanted to do and I think it looks kind of cool.
It is a flat plate wing with a thickness of 3/8". That gives it a 2.2% wing thickness at the root next to the equipment compartment and 5.2% at the tip. The two spars are 1/4" continuous basswood with balsa ribs. I cut out the 1/16" balsa wing skins and traced the plans onto them. Then I just glued the wood onto the wing skin on a flat surface.
It is a flat plate wing with a thickness of 3/8". That gives it a 2.2% wing thickness at the root next to the equipment compartment and 5.2% at the tip. The two spars are 1/4" continuous basswood with balsa ribs. I cut out the 1/16" balsa wing skins and traced the plans onto them. Then I just glued the wood onto the wing skin on a flat surface.
08-15-2009, 07:40 PM
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RE: Flat plate wing thing
It is looking like the airframe will come in just under 1 lb. Not too bad for 500 sq in and a 42" wing span. The black center section in the pictures is a cardboard cut out of what I may do. This build is going really quick and easy.
08-16-2009, 12:35 AM
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RE: Flat plate wing thing
Flutter?? My planes don't flutter. 
Well, except for my Jett 50 powered Shrike that I over sanded the ailerons. Hmm, and maybe one of my spad combat planes because of coroplast. Actually the airframe feels very solid after the top sheeting went on. I think it will be fine with about 80 Amps going through it. The frontal area is only 22 sq. in. compared to 35+ on my last Demon and 35 is not bad. I am ready to get it covered and figure out a good hatch.
Well, except for my Jett 50 powered Shrike that I over sanded the ailerons. Hmm, and maybe one of my spad combat planes because of coroplast. Actually the airframe feels very solid after the top sheeting went on. I think it will be fine with about 80 Amps going through it. The frontal area is only 22 sq. in. compared to 35+ on my last Demon and 35 is not bad. I am ready to get it covered and figure out a good hatch.
08-17-2009, 10:42 AM
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RE: Flat plate wing thing
The color scheme came out close to what I posted earlier. Haven't had a chance to start on the hatch yet and I am leaving the winglets off so they wont get damaged while I work on it. Weight less hatch is 12.7 oz. I suspect the hatch will be just over 1 oz..
08-17-2009, 10:51 PM
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RE: Flat plate wing thing
ORIGINAL: mk1spitfire
When's the maiden mike? Looks slipery..!
When's the maiden mike? Looks slipery..!
08-18-2009, 09:24 AM
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RE: Flat plate wing thing
With that setup I could probably have it RTF at 1.5 lbs. Wing loading about 7 oz. sq. ft. It would be slow and fast. Hmmm
08-18-2009, 09:54 AM
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RE: Flat plate wing thing
The part about highly stressed electric set ups I don't know about is this.........by the time you hear the motor sag, is it already too late? Have you unwittingly damaged the windings or taken some performance away that will never return?
With glow, you can usually get away with an overload or bad setting if you shut it down in reasonable time. Change the plug, cool it down and she's good as new.
The part about electric I do know about, [and it really bugs me].......that burst of power you get when it is first turned on, that bleeds off in short time, then you spend the bulk of the flight at 95% power wishing you could re-live the first 5 seconds of that flight at 100% power [&o]
With glow, you can usually get away with an overload or bad setting if you shut it down in reasonable time. Change the plug, cool it down and she's good as new.
The part about electric I do know about, [and it really bugs me].......that burst of power you get when it is first turned on, that bleeds off in short time, then you spend the bulk of the flight at 95% power wishing you could re-live the first 5 seconds of that flight at 100% power [&o]
08-18-2009, 09:03 PM
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RE: Flat plate wing thing
My goal is to have a set up that full throttle will only be at the maximum continuous safe power. Also, if it has 110% of the power I want, I will be at at least 100% most of the flight. All methods of power have their good and bad parts but I just want to try electric and see what it is all about. There is a fairly large initial investment so I hope I like it well enough to stay with it for awhile. Not cleaning the glow fuel off the plane (and me) will be one plus.
Waiting for the finishing epoxy to harden on the hatch so I can paint it. I hate using Monokote on curved areas and I tried to round all the corners some. Then the winglets. Maybe some finished (airframe) pics by tomorrow evening.
Waiting for the finishing epoxy to harden on the hatch so I can paint it. I hate using Monokote on curved areas and I tried to round all the corners some. Then the winglets. Maybe some finished (airframe) pics by tomorrow evening.
08-18-2009, 09:45 PM
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RE: Flat plate wing thing
ORIGINAL: combatpigg
The part about highly stressed electric set ups I don't know about is this.........by the time you hear the motor sag, is it already too late? Have you unwittingly damaged the windings or taken some performance away that will never return?
With glow, you can usually get away with an overload or bad setting if you shut it down in reasonable time. Change the plug, cool it down and she's good as new.
The part about electric I do know about, [and it really bugs me].......that burst of power you get when it is first turned on, that bleeds off in short time, then you spend the bulk of the flight at 95% power wishing you could re-live the first 5 seconds of that flight at 100% power [&o]
The part about highly stressed electric set ups I don't know about is this.........by the time you hear the motor sag, is it already too late? Have you unwittingly damaged the windings or taken some performance away that will never return?
With glow, you can usually get away with an overload or bad setting if you shut it down in reasonable time. Change the plug, cool it down and she's good as new.
The part about electric I do know about, [and it really bugs me].......that burst of power you get when it is first turned on, that bleeds off in short time, then you spend the bulk of the flight at 95% power wishing you could re-live the first 5 seconds of that flight at 100% power [&o]
If not, look out!
No as far as cooking the windings...
I have done that. You know your in trouble when your electric starts to trail smoke like a glow powered airplane. oops!
I have done that to a couple of airplanes and turned the motor to junk in one in the other I caught it quick and it has had a couple of flights since and seems fine (time will tell).
If you deal with high power electrics you must have some way of measuring the power you are dumping into the motor. Also a no contact type of thermometer or temperature sensor is a wise investment. Then you can start to do the dance of seeing just how had you can push them before you start blowing things up. You can overload them briefly and they will survive, but it is wisest to have equipment to test your setups when you are first putting everything together. I am well versed with electrical/electronic equipment and have a leg up as far as that goes when approaching the rc applications of this type of technology. You can get away with abusing them some (not a lot) and live to play another day, you can also push them so hard that other than smoke and a flash you never know what hit you as well. But generally you will know when you are getting into the danger zone by reading the specs on each piece you are using, when you dump 1200 watts into a 600 watt motor you know you may have "issues".
As far as what you are saying about the first part of the flight being awesome then it just starts to settle down there is a way around that but...
If you use a battery that has an amp hour rating that well exceeds the power you engine can handle you will get much better performance during the entire flight and you will not have that rapid drop off in performance. Now for the but part... With all that power available you tend to push it harder longer, unless you make ample provisions for cooling all of the parts including the batteries thinks will blow up. And then there is the cost of the high C batteries (although that is dropping of late) but still initial investment in chargers, meters and alike may be an issue. Up until recently high capacity high discharge batteries were not that common and very pricey, often you had to rig up combination's of cells to get any real performance and all of that added weight. My experince is that you want about twice the amps available from the battery than you can push though the ESC/motor combo and you will get decent overall performance for about ten minutes.
08-19-2009, 05:02 PM
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RE: Flat plate wing thing
The airframe is done so it is time to get serious about what will power it. Weight is about 15 oz with a 42 inch wingspan and 495 sq. in. I hope I can see it when it is coming at me.
08-19-2009, 08:03 PM
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RE: Flat plate wing thing
ORIGINAL: combatpigg
Looks outstanding Mike!
What set up would turn a 6x5 at 30,000?......that would be a good one just to get used to the plane with.
Looks outstanding Mike!
What set up would turn a 6x5 at 30,000?......that would be a good one just to get used to the plane with.
08-19-2009, 08:24 PM
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RE: Flat plate wing thing
I think you may well find the vne on this one...
The only problem as you may be finding out is the weight of the battery.
One other thing...
With an electric speed plane it may be best to take the Burt Rutan (or X-15) approach. Haul it aloft via another aircraft, and launch it then make your runs, will save you battery for when you are going for the gold...
The only problem as you may be finding out is the weight of the battery.
One other thing...
With an electric speed plane it may be best to take the Burt Rutan (or X-15) approach. Haul it aloft via another aircraft, and launch it then make your runs, will save you battery for when you are going for the gold...
08-19-2009, 08:35 PM
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RE: Flat plate wing thing
ORIGINAL: iron eagel
I think you may well find the vne on this one...
I think you may well find the vne on this one...
I wish you could hold and twist it in your hands to see how solid it is. Two hard wood spars and a lot of 1/8" and 3/16" balsa ribs sandwiched in between two sheets. I really do not think structural failure (in the air) is going to happen.
08-19-2009, 09:13 PM
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RE: Flat plate wing thing
Oh I think the airframe is pretty rigid...
I just think you may be surprised at just how fast you may be able to get it to go.
Power off high dive then BTW throttle, these electric motors can really spin some high revs...
They really start to sound like those FAI speed planes!
Reminds me of Darth Vader's tie fighter.
I just think you may be surprised at just how fast you may be able to get it to go.
Power off high dive then BTW throttle, these electric motors can really spin some high revs...
They really start to sound like those FAI speed planes!
Reminds me of Darth Vader's tie fighter.
08-19-2009, 11:48 PM
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RE: Flat plate wing thing
cp
the batteries i like are the A123 LiFe cells, rigth now you can by 4s packs for 35.00 each on fleecebay, they have the absolute best c rating to be had, and dont puff or whine under extreme load....i bought 8 packs NIB for my foray into electric mayhem lifespan exceeds 1000 cycles.
the batteries i like are the A123 LiFe cells, rigth now you can by 4s packs for 35.00 each on fleecebay, they have the absolute best c rating to be had, and dont puff or whine under extreme load....i bought 8 packs NIB for my foray into electric mayhem lifespan exceeds 1000 cycles.