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Pumpkin drop event

Fire Fighting Plane "Challenge

Hai-Lee

Old and Bold RC PILOT
#62
If you would still to operate flaps on the plane and only use the 4 channels it can be done but not at extreme flap deflections.

Simply in take off mode the craft will be at its maximum weight and at landing it minimum! Therefore the lift required at take off is far higher than at landing! To achieve this it is possible to "Y" harness the throttle output and use it to drive the flap servos. Result: On take off and at maximum throttle the flaps are fully extended as they are through the climb out. At height and as you reduce the throttle the flaps retract in proportion to the throttle reduction.

After the load is released the plane can be throttled back further and cruise back to the landing strip. Landing with minimal throttle is also done with minimum or zero flaps. It does work and it does predetermine your mission profile but without adding an additional channel or the need to buy a replacement transmitter just yet.

If using inboard flaps and you wish to mix in ailerons as well then I recommend the old style mixing tray where you can set the mix ratios simply and statically without the need for a new programmable transmitter. I would use standard ailerons outboard, (no flap mix).

Just a recollection of the way things were done when I was young and RC was new!

Have fun!
 

quorneng

Well-known member
#64
IcedStorm777
In general a wing can never be too rigid!
Remember if a wing flexes in flight it can also twist as it does so and wings are very sensitive to variation in the angle it is at compared to the air flow (angle of attack). It can take a lot of 'design' to create a wing that bends and yet avoids twisting at the same time.

Your foam board wing is likely to be adequately stiff enough to resist any aerodynamic twisting forces when "at rest" but there is no guarantee it will not twist as flying loads cause it to bend. The one thing you do not want is for it to twist under load so the wing tip increases its angle of attack. This condition can make the plane hard to control or even cause the wing to fold!

So plenty of stiffness and preferably arranged so that any wing bend results in either no twist or at least twist that reduces the angle of attack at the tip.
To calculate exactly how a wing might bend and twist is a mathematical nightmare and its even pretty hard to measure twisting under load so it comes down to either experience or simply copy the features of a proven wing design.
 
#65
IcedStorm777
In general a wing can never be too rigid!
Remember if a wing flexes in flight it can also twist as it does so and wings are very sensitive to variation in the angle it is at compared to the air flow (angle of attack). It can take a lot of 'design' to create a wing that bends and yet avoids twisting at the same time.

Your foam board wing is likely to be adequately stiff enough to resist any aerodynamic twisting forces when "at rest" but there is no guarantee it will not twist as flying loads cause it to bend. The one thing you do not want is for it to twist under load so the wing tip increases its angle of attack. This condition can make the plane hard to control or even cause the wing to fold!

So plenty of stiffness and preferably arranged so that any wing bend results in either no twist or at least twist that reduces the angle of attack at the tip.
To calculate exactly how a wing might bend and twist is a mathematical nightmare and its even pretty hard to measure twisting under load so it comes down to either experience or simply copy the features of a proven wing design.
Ok thank you. My dad and i held the wing by the tips and tried to get it to flew and it flexed very very little. I was very impressed. Thank you for all your help as i knew NONE of this stuff before i started. ( I am only fourteen so still know very very little aerospace engineering, aerodynamics, and physics.)
 
#66
Ok here is a little bit of an update, sorry i have been busy and haven't be able to do much as i have been working on my trainer jet and repairing other planes i got in a great deal. The only things i really need to do to finish this beast up are: attach ailerons, add servos, figure out where the wiring goes, and then the most important thing left. This being adding the four motor mounts and soldering the ESc's and motors. Unf as i don't know how to solder, i have to wait for a friend to be able to help me. @Tjhochha how is your build coming along?
 

Tjhochha

Active member
#67
Ok here is a little bit of an update, sorry i have been busy and haven't be able to do much as i have been working on my trainer jet and repairing other planes i got in a great deal. The only things i really need to do to finish this beast up are: attach ailerons, add servos, figure out where the wiring goes, and then the most important thing left. This being adding the four motor mounts and soldering the ESc's and motors. Unf as i don't know how to solder, i have to wait for a friend to be able to help me. @Tjhochha how is your build coming along?
Cool! It sounds like you are getting close to taking to the air. I wish I could give you some tips on soldering but I’m the worst at it.

I finally got my motors and other parts from FT after they somehow took a wrong turn. They made it to Montana then somehow ended up in Puerto Rico before coming back to Montana.
I am a bit surprised at where the CG ended up after getting all the electronics in. After the build, it seemed like it was going to be tail heavy but with the motors and batteries, it ended up a bit forward of where my calcs showed it should be.
I took her up for a maiden yesterday and after a bit of a sketchy start I got it trimmed out and it flies great! It has plenty of power with the twin C-pack. It can nearly climb vertical, it possibly can with differential thrust and some more practice. It did loops and barrel rolls pretty cleanly. I even did some accidental high g maneuvers and the wing spars seemed to take it fine.
Here is a clip from my maiden flight.
Now to just figure out how to set up some bomb bay doors.

Have fun and keep up the good work.
Teich
 
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#68
Wow thats awesome congratulations! That was one of the best maidens i have ever seen, looked almost like a horizon hobby plane (because it flew so well). Would you mind sending a picture of the plane with something (maybe like a lego or a paper clip) on where the CG is of the plane? Thanks!
 

Tjhochha

Active member
#69
Wow thats awesome congratulations! That was one of the best maidens i have ever seen, looked almost like a horizon hobby plane (because it flew so well). Would you mind sending a picture of the plane with something (maybe like a lego or a paper clip) on where the CG is of the plane? Thanks!
Sorry, I haven't been ignoring you, just a busy couple of days, I'll try to take a pic tonight when I get home.
Here is the calculator I used to find my CG. https://www.ecalc.ch/cgcalc.php It's pretty cool, and seemed to do the trick. The CG it showed for my plane is about 2.6-2.9" from the leading edge. With my setup, I ended up at about 2.3" from the leading edge so it's still a little nose heavy based on the calcs.

I have done some work over the last few days to start closing up the open bottom of the plane and shifting my receiver to behind the bomb bay. I have also been working on a plan to operate some doors for the bottom of the fuse to drop stuff out of. I got a Flysky TX/RX for Christmas so I have been messing with that to try to get it set up for my plane. It only has 3 mix setups so it looks like I can only do differential thrust OR other mixes, like flaperons and mixed ailerons and rudder. Other than the somewhat light/chintzy feel and only having 3 mixes, it seems like a good controller. It does seem to suck through the batteries though. I haven't flown with it yet and I've already used 1/3 of the battery just setting it up.
 

Tjhochha

Active member
#70
Well, I got my new transmitter set up and the Rex installed in my P2V. The differential thrust and rudder seem to be working correctly. Hopefully the wind stops blowing tomorrow so I can take it up for a test flight with the new transmitter.

I finally remembered to take a pic with the CG shown. The two skewers in the wings show where it’s supposed to be. The bottle cap is closer to where it actually is.
23A74092-EA0E-43A1-B62A-2691AB54F559.jpeg
The bottle cap and cat are for scale.
 
#73
No actually thats really cool, thank you, i have been super busy working on my jet and unfortunately i don't know how to solder which is really one of the only things i still need to do for the Fire fighting plane. Did you maiden yours?
 

Tjhochha

Active member
#74
No actually thats really cool, thank you, i have been super busy working on my jet and unfortunately i don't know how to solder which is really one of the only things i still need to do for the Fire fighting plane. Did you maiden yours?
I found that link while looking for ways to waterproof DTFB the other day. I did take it up on the new transmitter and it flew alright, I think a lot of my problems were, I put in a lot of expo to see what it was like and that made things a bit tougher on me after learning on a linear transmitter. I did end up crashing after 5 minutes or so, nothing too serious. I just pancaked it and broke a prop, the little turbine pod thing and the BBQ pins that fix the wing to the fuse.
It's been kind of crappy here the last few weekends so I started working on a sea duck. Hence the waterproofing search. I made some mods to the nacelles to fit my C-pack power pods from my P2V. I'm too cheap to buy another power setup. I based my P2V wing design off of the sea duck so I figured it would be similar size but so far the wings on the sea duck seem huge.
 
#76
So i finished the wing mount. The first picture is of the wing unmounted with both spars in place (although the circular dowl is uncut). View attachment 119985 The second Picture is of the wing mounted fully attached to the fuselage. View attachment 119986 The third picture is how i did the wing mount. I have two pieces of wood on top of the wing. These are bolted through two layers of foam and one layer of wood to the inside of the fuselage. View attachment 119988 The last picture is of me with the plane. Airfoil isn't glued yet. The exterior wing pieces also need to be screwed in. Then just need to View attachment 119993 Finished it at about 11 so was very tired.
hello! It’s September and your photos are still helping others and making me smile. Do you have a link to finished photo and maiden story!? You have a gift for great looking builds..... congrats and thanks.
 
#77
hello! It’s September and your photos are still helping others and making me smile. Do you have a link to finished photo and maiden story!? You have a gift for great looking builds..... congrats and thanks.
Haha Thanks! Im really a newb at building and i really didn't think they looked to great so thanks for the inspiration! Soon after i mounted the wings i discovered that the motors and ESC's i was going to build this were all bad. ( Someone had given them to me and i had forgotten to check them). I didn't have the money at the time and then i moved on to another project. I will probably pick it back up sometime i just don't know when.
 

L Edge

Well-known member
#78
I found that link while looking for ways to waterproof DTFB the other day. I did take it up on the new transmitter and it flew alright, I think a lot of my problems were, I put in a lot of expo to see what it was like and that made things a bit tougher on me after learning on a linear transmitter. I did end up crashing after 5 minutes or so, nothing too serious. I just pancaked it and broke a prop, the little turbine pod thing and the BBQ pins that fix the wing to the fuse.
It's been kind of crappy here the last few weekends so I started working on a sea duck. Hence the waterproofing search. I made some mods to the nacelles to fit my C-pack power pods from my P2V. I'm too cheap to buy another power setup. I based my P2V wing design off of the sea duck so I figured it would be similar size but so far the wings on the sea duck seem huge.
One question, did you do any plans at all?
I have over 1600 hrs(flight engineer) in p2v's (5 and 7f) and would love to make a model after our squadron.
Hope to hear from you.
 
#79
Haha Thanks! Im really a newb at building and i really didn't think they looked to great so thanks for the inspiration! Soon after i mounted the wings i discovered that the motors and ESC's i was going to build this were all bad. ( Someone had given them to me and i had forgotten to check them). I didn't have the money at the time and then i moved on to another project. I will probably pick it back up sometime i just don't know when.
Thanks! Good luck, you made my day...
miggy