Flite Fest 2022 Community Challenge – WWI “Dawn Patrol”

NerdyKid

New member
1) Personally, I like the semi-symmetrical airfoils like the Clark-Y because they're easier to make stiff and strong than an undercambered airfoil. Undercambered will probably need functional cross bracing between the wings to keep it strong enough.

2) I haven't seen the original specs, but I highly doubt that the CG was actually behind the NP of the wing. If you shared some of your research we might be able to help verify this and/or determine where it should be.

The wing looks pretty good to me, a good start and compromise between strength, ease of building, and scale.

I found this diagram from a post on the RCU forum and here is a quote from the guy that translated it

”Quite surely фокус (the middle point) means Neutral Point.

Since цеитр тяжести means center of gravity, the abbreviation ц.т (the right point) should indeed translate to C/G.”

1643917642402.png

Between the size of the tail and the length of the nose, I don't think you will be able to get a plane like this balanced using the standard 1/4 back rule. I think you will have to treat the plane like a tanden wing design (think Flying Flea) and figure the horizontal tail as a third, rear wing. Considering it like that, a CG point near the TE would then make sense.

I think you‘re right about treating this like a tandem setup, which actually a bit of a relief since I don’t know how I would’ve put nose weight in this.

Thanks all for your advice, this is the first plane I’ve designed so I don’t really know what I’m doing.
 

cyclone3350

Master member
I found this diagram from a post on the RCU forum and here is a quote from the guy that translated it

”Quite surely фокус (the middle point) means Neutral Point.

Since цеитр тяжести means center of gravity, the abbreviation ц.т (the right point) should indeed translate to C/G.”

View attachment 217819



I think you‘re right about treating this like a tandem setup, which actually a bit of a relief since I don’t know how I would’ve put nose weight in this.

Thanks all for your advice, this is the first plane I’ve designed so I don’t really know what I’m doing.

I've designed many & I still don't know what I am doing! But so far, it looks like U R doing it right & asking the right questions.
 

The Fopster

Master member
Right - here we go. For the first time in about 6 months, this evening I cut some foamboard. Sopwith Pup from balsa plans found on Outerzone, scaled up 147% to make them 1/6th scale. An hour got a basic box for the fuselage. Wonder how long it would have taken to frame up a balsa version? That’s why I like building from foamboard - that and the crash resilience/repairability.
59049CE9-4EEF-4360-A1CC-C9155CFEDA90.jpeg
590AD164-CE2B-4614-9345-7BCC7BA6C54F.jpeg
 

Tench745

Master member
I found this diagram from a post on the RCU forum and here is a quote from the guy that translated it

”Quite surely фокус (the middle point) means Neutral Point.

Since цеитр тяжести means center of gravity, the abbreviation ц.т (the right point) should indeed translate to C/G.”

View attachment 217819



I think you‘re right about treating this like a tandem setup, which actually a bit of a relief since I don’t know how I would’ve put nose weight in this.

Thanks all for your advice, this is the first plane I’ve designed so I don’t really know what I’m doing.

I just went back and looked at the 3-views for this plane. I didn't realize how large the H-stab was, and it is clearly a lifting tail, so it will act like another wing. That will definitely push the desired CG aft.

For difficult to figure CG situations I find this calculator https://www.ecalc.ch/cgcalc.php to be very helpful. It will work in imperial or metric and you can plug in dimensions for each station of the wing and the tail. It draws a top-view of the wing plan as you input data and will spit out CG and other useful data when you hit "calculate." Make sure to select "Biplane" from the first drop-down menu so you can input both upper and lower wing information.
 

Spitfire76

Well-known member
My design is going to require a non-removal wing and although with the 1/9th scale thats not such a problem but transportation could be if I upscale it to 1/6th in which case I would likely to need to be able to somehow have it removal and preferable in separate halves. Has anyone come up with a solution that would securely connect each wing ?.
 

wilmracer

I build things that fly (sometimes)
Mentor
Right - here we go. For the first time in about 6 months, this evening I cut some foamboard. Sopwith Pup from balsa plans found on Outerzone, scaled up 147% to make them 1/6th scale.

Awesome! Glad to see another bird started and glad your back into the world of foam :). If you could please start a dedicated build thread and send me the link so I can update the first post. We want to follow along on the build but I also want to keep this thread "lean" for general info and conversation about the event.

That is going to be a good looking pup! Keep it up!
 

wilmracer

I build things that fly (sometimes)
Mentor
My design is going to require a non-removal wing and although with the 1/9th scale thats not such a problem but transportation could be if I upscale it to 1/6th in which case I would likely to need to be able to somehow have it removal and preferable in separate halves. Has anyone come up with a solution that would securely connect each wing ?.

There are a lot of options but I like to use wing tubes and sleeves with retaining bolts... BUT for this scale and speed I'm betting simple magnets would hold the wing on tight, particularly once the spar is under load in flight. This is what I'm using on the albatros at 1:4 scale. I still need to get them uploaded to thingiverse. Instead of the tube and sleeve you could use a wood or aluminum spar that slips into a "socket"


Get a build thread going and we'll share lots of options there!
 

mastermalpass

Elite member
I just went back and looked at the 3-views for this plane. I didn't realize how large the H-stab was, and it is clearly a lifting tail, so it will act like another wing. That will definitely push the desired CG aft.

For difficult to figure CG situations I find this calculator https://www.ecalc.ch/cgcalc.php to be very helpful. It will work in imperial or metric and you can plug in dimensions for each station of the wing and the tail. It draws a top-view of the wing plan as you input data and will spit out CG and other useful data when you hit "calculate." Make sure to select "Biplane" from the first drop-down menu so you can input both upper and lower wing information.

That is the most useful and accessible online tool I've ever seen! *Bookmarked* I've always wondered where you CG bipe.
 

cyclone3350

Master member
Right - here we go. For the first time in about 6 months, this evening I cut some foamboard. Sopwith Pup from balsa plans found on Outerzone, scaled up 147% to make them 1/6th scale. An hour got a basic box for the fuselage. Wonder how long it would have taken to frame up a balsa version? That’s why I like building from foamboard - that and the crash resilience/repairability.
View attachment 217837 View attachment 217838
Definitely looking forward to seeing this one done(y)
 

Spitfire76

Well-known member
There are a lot of options but I like to use wing tubes and sleeves with retaining bolts... BUT for this scale and speed I'm betting simple magnets would hold the wing on tight, particularly once the spar is under load in flight. This is what I'm using on the albatros at 1:4 scale. I still need to get them uploaded to thingiverse. Instead of the tube and sleeve you could use a wood or aluminum spar that slips into a "socket"


Get a build thread going and we'll share lots of options there!
Thanks for that solution. I do have a build log started for my 1/9th scale but not yet for the 1/6
https://forum.flitetest.com/index.p...c-2022-build-off-challenge.69257/#post-700799
 

mastermalpass

Elite member
My project commences! Well, to be honest it started when I first posted in this thread, but I have racked up some nice material to show for it now - that being drawings.

1644105987045.png


I am now at a stage where I feel I've got enough theory sorted out and am now ready to start looking at making something physical. I will no doubt need to return to measuring for things like struts and other minor details, but the bulk of the airframe has been essentially figured out, assuming things don't go drastically wrong when I try to assemble the concept model.
 

The Fopster

Master member
My project commences! Well, to be honest it started when I first posted in this thread, but I have racked up some nice material to show for it now - that being drawings.

View attachment 218052

I am now at a stage where I feel I've got enough theory sorted out and am now ready to start looking at making something physical. I will no doubt need to return to measuring for things like struts and other minor details, but the bulk of the airframe has been essentially figured out, assuming things don't go drastically wrong when I try to assemble the concept model.
Those look exactly like the kind of scribbling I do before I start a build - except yours are much nicer! If the build looks as nice as the sketches this’ll be a fantastic model.
 

mastermalpass

Elite member
Those look exactly like the kind of scribbling I do before I start a build - except yours are much nicer! If the build looks as nice as the sketches this’ll be a fantastic model.

I can't hype my draftsmanship up too much, the second picture was done by dropping a page over my laptop screen and tracing the blueprint. I too hope the build turns out as nice as the sketch - I have no idea how I'm going to form the skin. Do I do lots of long strips up and down, nose to tail, or lots of hoops stacking end-to-end? That's the challenge with something that curves along both axis. I can see myself covering it in spackle and sanding, if that doesn't add too much weight.
 

FlyerInStyle

Elite member
I found this diagram from a post on the RCU forum and here is a quote from the guy that translated it

”Quite surely фокус (the middle point) means Neutral Point.

Since цеитр тяжести means center of gravity, the abbreviation ц.т (the right point) should indeed translate to C/G.”

View attachment 217819



I think you‘re right about treating this like a tandem setup, which actually a bit of a relief since I don’t know how I would’ve put nose weight in this.

Thanks all for your advice, this is the first plane I’ve designed so I don’t really know what I’m doing.
I just want to note, since I can speak russian, фокус will translate to focus point, imply it however you want.
 

Newwood

New member
I posted this on the FTF Facebook page and it was suggested I post here as well.

I came across some pictures of a Junkers D1 some time ago, never knew this plane existed but I really liked it's lines. Being new to the hobby and possessing ten thumbs when it comes to computer knowledge I was unable to find any plans for this plane so I did it the old fashioned way.... I stared at photos until I was ready to pass out, found the actual plane dimensions, scaled it down to about 1/8 and started cutting foam.

I think it turned out OK. It is not exact scale but close enough for me. The original plane has the wings so far forward that I thought that staying true to scale would result in serious balance issues. Unlike the real thing, our models don't have an 8000 # Mercedes Benz engine to balance things out. As a result I shortened the fueslage a couple inches and moved the wing back about 1 inch. With a 9 inch wide wing it balances very nicely with the CG 2 3/4" from leading edge. We will see how it flies in the spring, last week our thermometer read -37, (thats minus 37) here in northern Wisconsin, no flying for me anytime soon.
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I think this model would be a great addition to the challenge unfortunately I won't be able to make to Flite Fest. The date change puts it in conflict with our family vacation.
 

mastermalpass

Elite member
I posted this on the FTF Facebook page and it was suggested I post here as well.

I came across some pictures of a Junkers D1 some time ago, never knew this plane existed but I really liked it's lines. Being new to the hobby and possessing ten thumbs when it comes to computer knowledge I was unable to find any plans for this plane so I did it the old fashioned way.... I stared at photos until I was ready to pass out, found the actual plane dimensions, scaled it down to about 1/8 and started cutting foam.

I think it turned out OK. It is not exact scale but close enough for me. The original plane has the wings so far forward that I thought that staying true to scale would result in serious balance issues. Unlike the real thing, our models don't have an 8000 # Mercedes Benz engine to balance things out. As a result I shortened the fueslage a couple inches and moved the wing back about 1 inch. With a 9 inch wide wing it balances very nicely with the CG 2 3/4" from leading edge. We will see how it flies in the spring, last week our thermometer read -37, (thats minus 37) here in northern Wisconsin, no flying for me anytime soon. View attachment 218264 View attachment 218265 View attachment 218266 View attachment 218267

I think this model would be a great addition to the challenge unfortunately I won't be able to make to Flite Fest. The date change puts it in conflict with our family vacation.

That is gorgeous! First pic had me thinking it was a modified mini scout, but then reading about the nose-to-wing distance and having to make adjustments there all the other details shone out to me. I just love how some of the close ups reveal how simple the little details are which come together to make a real scale looking model. I often find its the little things that seem to add so much, Pitot tubes and little antenna fins and that.

This model has a relatively short vertical stab for a wing of this size. How is it in air? :)
 

Newwood

New member
That is gorgeous! First pic had me thinking it was a modified mini scout, but then reading about the nose-to-wing distance and having to make adjustments there all the other details shone out to me. I just love how some of the close ups reveal how simple the little details are which come together to make a real scale looking model. I often find its the little things that seem to add so much, Pitot tubes and little antenna fins and that.

This model has a relatively short vertical stab for a wing of this size. How is it in air? :)

Thanks for the compliment! I am really new at this, it was about a year ago when I found the FT videos on Youtube and away I went. Just finished it up the other day. Have not flown it yet, I live in northern Wisconsin and between the snow and cold I am going to wait for better weather.
 

mastermalpass

Elite member
Thanks for the compliment! I am really new at this, it was about a year ago when I found the FT videos on Youtube and away I went. Just finished it up the other day. Have not flown it yet, I live in northern Wisconsin and between the snow and cold I am going to wait for better weather.

Smart move, especially if you're new. I avoided wind like the devil when I first started. I like it most in the summer where the winds die down at 20:30 - 21:00 and you can fly in the sunset. In winter I found it's best to rise at dawn if you want the calmest conditions, but the south west of the UK probably isn't quite as snowy as Wisconsin... And that paint job will blend right in with snow and snow clouds!
 

The Fopster

Master member
I posted this on the FTF Facebook page and it was suggested I post here as well.

I came across some pictures of a Junkers D1 some time ago, never knew this plane existed but I really liked it's lines. Being new to the hobby and possessing ten thumbs when it comes to computer knowledge I was unable to find any plans for this plane so I did it the old fashioned way.... I stared at photos until I was ready to pass out, found the actual plane dimensions, scaled it down to about 1/8 and started cutting foam.

I think it turned out OK. It is not exact scale but close enough for me. The original plane has the wings so far forward that I thought that staying true to scale would result in serious balance issues. Unlike the real thing, our models don't have an 8000 # Mercedes Benz engine to balance things out. As a result I shortened the fueslage a couple inches and moved the wing back about 1 inch. With a 9 inch wide wing it balances very nicely with the CG 2 3/4" from leading edge. We will see how it flies in the spring, last week our thermometer read -37, (thats minus 37) here in northern Wisconsin, no flying for me anytime soon. View attachment 218264 View attachment 218265 View attachment 218266 View attachment 218267

I think this model would be a great addition to the challenge unfortunately I won't be able to make to Flite Fest. The date change puts it in conflict with our family vacation.
That’s a great looking build. Particularly like the paint job - really well executed. If you’d said you’d been designing and building these for a decade I wouldn’t have batted an eyelid. Congratulations!