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-   -   dihedral on low or mid wing (http://www.Wattflyer.com/forums/showthread.php?t=68910)

paulatgis 12-05-2012 02:40 AM

dihedral on low or mid wing
 
im gona to scratch build from 3 views. i have a mid wing plan, but for simplicicty want to make it a low wing. my concerns are dihedral on the wing. it seems I can make the wing flat to avoid warping or deviations, but then would consider cutting the wing at midway if dihedral is required.

i prefer mainly to minimize stall characteristics. the wing is 60 inches, semitrical and has a 12 in constant chord with naca 0018. first i build the wing then the fuse.

im interested in nice quick rolls and plan on sufficient aileron size to handle this.

any suggestions? mid wing with X dihedral. low wing and Y dihedral?

maybe i should review the designs of pattern planes. Thanks!

tobydogs 12-05-2012 03:45 AM

3 Attachment(s)
need more information....can you show a drawing of the build and what materials your using:confused:. i build balsa kit and bash them to add ailerons. the less dyhedrial the better the rolls:Q...and the harder to control but thats to be expected.

i'v modified several 3channel sig kits to have ailerons and a aerocraft skimmer 600 sail plane.

of the 2 sig breezyday parkflyers i find the red one with more dyhedrial easyer to fly and very aerobatic. the yellow one fly fast and and reacts quicker to fly. so share a little more info on your build and folks here can help i'm sure.:ws:

rcers 12-05-2012 02:46 PM

Quote:

Originally Posted by paulatgis (Post 891017)
im gona to scratch build from 3 views. i have a mid wing plan, but for simplicicty want to make it a low wing. my concerns are dihedral on the wing. it seems I can make the wing flat to avoid warping or deviations, but then would consider cutting the wing at midway if dihedral is required.

i prefer mainly to minimize stall characteristics. the wing is 60 inches, semitrical and has a 12 in constant chord with naca 0018. first i build the wing then the fuse.

Zero dihedral "looks" funny so you need some just for the looks factor. It will appear to droop if completely flat.

Most planes benefit from dihedral as well. On a fun scratch built you dont' need much just try an inch or so in each tip for a 60" wing maybe a touch more.

However dihedral has NOTHING to do with stall characteristics. That is more governed by several factors:
  • Airfoil (as you point out)
  • LE shape (blunt/sharp - makes a difference)
  • Weight of the model and wing loading
  • Thickness of the airfoil
Mike

road king 97 12-05-2012 02:53 PM

4 Attachment(s)
This has no dihedral at all and flys fine .rolls are very fast and it is also a 60 inch wing span .Iam scratch building its smaller foam twin again with no dihedral and a 38 inch wing span. joe

xmech2k 12-05-2012 06:53 PM

Aren't planes without dihedral more likely to need rudder input to turn well? (Canards aside!)

road king 97 12-05-2012 07:06 PM

Quote:

Originally Posted by xmech2k (Post 891059)
Aren't planes without dihedral more likely to need rudder input to turn well? (Canards aside!)

Btw if you want dihedral building the wing like i did my straight one it only requires you to cut the main spar with dihedral in it and glue the two halfs together or prop up both sides and then use a doubler . It does not take any longer to build a wing with or without it in foam. :D You have all these flat profile planes flying around with flat wings and some with no rudder so i would not worry about it to much. joe

JetPlaneFlyer 12-05-2012 08:50 PM

low wing with no dihedral tends to produce a panes that's laterally unstable which isn't a big issue if you are an experienced flyer but isn't really ideal. A small amount of dihedral is usually a good idea for low wing models (a couple of degrees maybe). For mid wing zero dihedral works well.

This assumes you are talking about a aileron controlled aerobatic model where you don't want any significant lateral stability ('self righting' tendency). If you want the plane to be very stable and/or fly on rudder only then you will need lots of dihedral.

paulatgis 12-06-2012 12:55 AM

2 Attachment(s)
great info. here's a few pictures.

i can build the wing flat, then cut in half and and a small amount of diehedral. just laying flat now it does look to droop, but maybe thats just my thick glasses.

sounds like I can add maybe an inch at the wing tip of dihedral if its going on the fuse shoulder or mid fuse. then maybe another inch or less totalling 1.5 inches at tip if i put the wing on the bottom of the fuse.

how about if I review these items
  • Airfoil (as you point out)
  • LE shape (blunt/sharp - makes a difference)
  • Weight of the model and wing loading
  • Thickness of the airfoil
1) airfoil is naca 0018 semitrical.
2) blunt LE - well round as a nickel or quarter.
3)wing loading should be low - i build light but this time will put a big motor and big battery. its go 60 inch by 12 inch chord without including ailerons which is about 5 square feet. auw expected will be 5 to 6 lbs.
4) thick wing naca 0018

hows my stall characteristics looking?

im not an expert flyer, but pretty good still.

stuart, i have a sig s flutterbug with foam wing (shoulder mount) it looks to have too much dihedral i cut down when i start that project. good idea!

road king 97 12-06-2012 01:20 AM

1 Attachment(s)
I would cut it the middle then prop up one side 2 inches and the other flat on the table that will give you your 1 inch at each tip .Once all the balsa main spars to touch right cut a place for a double made out of thin ply on the correct angles and use a little epoxy to glue them to the back of your main spars . A double about 12 inches or so long 6 inches on each side of the center joint should be enough so it won;t snap off later. As far a airfoils and other teck stuff iam not that smart but i have been building for 30 years now with not one plane that did not fly or fell apart .lol This one flys with a 3/32 main spar with 1/8 x1/8 spruse strips on top and bottom of it on the sides and i stagered the joints . I haved looped this 100 inch plane and nothing has snapped yet. I learned alot from the airfield site about building http://airfieldmodels.com/informatio..._panels/03.htm

tobydogs 12-06-2012 01:55 AM

joe,that is a really beautiful build. do you have a build thread on it or a picture of the finished bird. very nice!!![popcorn]stu

road king 97 12-06-2012 02:01 AM

7 Attachment(s)
Quote:

Originally Posted by stuart (Post 891104)
joe,that is a really beautiful build. do you have a build thread on it or a picture of the finished bird. very nice!!![popcorn]stu

Sure here ya go. My build thread was here on wattflyers . joe http://www.wattflyer.com/forums/showthread.php?t=60775

paulatgis 12-06-2012 02:17 AM

thats the float plane i wanted to build, but my scaled down prototype kept submerging and never got in the air. nice job.

now about rejoining the wings. would you suggest i cut the center wing ribs and two nearest most all teh way through or partially - partially perhaps to keep some rib strength? i usually do partial then run half spars from both sides into the other wing half which i glue and wrap well in thread the two to form a solid joint there by foregoing the diehedral brace. which i cant do if i glue it all up and cut down the middle. hmm maybe i can.

road king 97 12-06-2012 02:21 AM

Quote:

Originally Posted by paulatgis (Post 891111)
thats the float plane i wanted to build, but my scaled down prototype kept submerging and never got in the air. nice job.

now about rejoining the wings. would you suggest i cut the center wing ribs and two nearest most all teh way through or partially - partially perhaps to keep some rib strength? i usually do partial then run half spars from both sides into the other wing half which i glue and wrap well in thread the two to form a solid joint there by foregoing the diehedral brace. which i cant do if i glue it all up and cut down the middle. hmm maybe i can.

What are you going to use for sheeting the wing or are you putting covering right over the framing ?

paulatgis 12-06-2012 02:22 AM

hi joe. whats the thickness on your wing? ball park is fine, thick or medium. aren't you ailerons on the wrong side of the wing?

paulatgis 12-06-2012 02:30 AM

oh i see joe. i checked out that link. i was not planning on sheeting the wing center for strength which later would support teh middle cut. my center ribs are blue foam not balsa so i was hesitant on letting the two middle foam ribs support the joint without a diheldral brace.

road king 97 12-06-2012 02:30 AM

Quote:

Originally Posted by paulatgis (Post 891113)
hi joe. whats the thickness on your wing? ball park is fine, thick or medium. aren't you ailerons on the wrong side of the wing?

My foam wing that iam building now is a little under 3/4 thick at the thickest part of the airfoil ,as far as the ail they will go at the rear of my wing as normal the elev is in front because its a canard plane . lol Iam scratch building both a balsa one and a smaller one .WHY ? cause i can.lol :D I scaled it down by pulling up the pdf and viewing it on my computer screen at 200 persent witch gave me a 38 inch wing span,WHY that way beacuse i never went to school and only learned to run a computer a couple years ago. lmao:D joe

road king 97 12-06-2012 02:35 AM

Quote:

Originally Posted by paulatgis (Post 891115)
oh i see joe. i checked out that link. i was not planning on sheeting the wing center for strength which later would support teh middle cut. my center ribs are blue foam not balsa so i was hesitant on letting the two middle foam ribs support the joint without a diheldral brace.

As long as you brace the center of the main spars to your satisfaction i would not worry about it. I would not cut ribs or anything else .If you can find some light hard wood it would always be better than ply . After building a couple different kinds of foam wings i like the method i showed you before ,when folded over its ready for paint and a stout piece of balsa for the main spar wraped over the top bottom and both sides stop it from breaking very well.I learned it by building this plane and he used no wood spar on his 3-d plane . http://www.rcgroups.com/forums/showt...ghlight=ultron

paulatgis 12-06-2012 02:53 AM

2 Attachment(s)
yeah. i dont like cutting the center ribs. maybe no big deal after gluing all back togther but definitely dont sant to cut those spars in the center, then id have to add a brace.

heres a close up of the wing joint i will cut to add dihedral. im gonna lose all that strength because its a single 1 inch by 3/8 inch spar. pic 2 shows how i split that into two in antoher plane - two 1/2 inch by 3/8 inche extended spars which i slid together and wrapped up with thread and ca.

i might have to just save those 1x3/8 spars and replace with two 1/2x3/8 which I can slide together only this time leae teh second out until after i cut and make the dihedral. same effect - add long 1x3/8 spanning both wings to skip a dihedral brace and cutting the ribs.

road king 97 12-06-2012 02:58 AM

Quote:

Originally Posted by paulatgis (Post 891120)
yeah. i dont like cutting the center ribs. maybe no big deal after gluing all back togther but definitely dont sant to cut those spars in the center, then id have to add a brace.

heres a close up of the wing joint i will cut to add dihedral. im gonna lose all that strength because its a single 1 inch by 3/8 inch spar. pic 2 shows how i split that into two in antoher plane - two 1/2 inch by 3/8 inche extended spars which i slid together and wrapped up with thread and ca.

i might have to just save those 1x3/8 spars and replace with two 1/2x3/8 which I can slide together only this time leae teh second out until after i cut and make the dihedral. same effect - add long 1x3/8 spanning both wings to skip a dihedral brace and cutting the ribs.

You got the right idea when you cut the wing spars in the center to get your dihedral the you put a piece of hard wood behind or in front to go ever the joint you cut.You could cut the rib out so you then could put one double over the top and bottom spar when you slide the double in reglue the rib to your new wing doubler .

paulatgis 12-06-2012 03:16 AM

hey joe. i think your prop is on backwards. does that fly forward or backwards? pretty nice though. looks like a fancy drone. ive always wanted to try that out. i went to dc and nat air and space museum to see the drones just recently. add fpv to drones and new ball game for ... well those that do what they gotta do. get some video of yours. id like to see.

im a programmer, so i was thinking of multi fpv in tandom of 8 drones from a single controller w/ ai of course - at least the latest ai, still not as smart as in the movies.

road king 97 12-06-2012 03:24 AM

Quote:

Originally Posted by paulatgis (Post 891128)
hey joe. i think your prop is on backwards. does that fly forward or backwards? pretty nice though. looks like a fancy drone. ive always wanted to try that out. i went to dc and nat air and space museum to see the drones just recently. add fpv to drones and new ball game for ... well those that do what they gotta do. get some video of yours. id like to see.

im a programmer, so i was thinking of multi fpv in tandom of 8 drones from a single controller w/ ai of course - at least the latest ai, still not as smart as in the movies.

If you ever need any plans just pm me i have over 6000 of them on different sites all over the world .I found a truk today on a argentine site.lol here are the plans for that canard for a free download ,they are under the picture and the build manuel is there to.
http://www.eurekaaircraft.com/plan_k...nard_stick.htm

paulatgis 12-06-2012 03:36 AM

think about it. moores law also applies to drones and fpv. a swarm of bees (fpvs). canard design might be the way to go. let me know how your canard works out. sounds like a fun project.

road king 97 12-06-2012 03:41 AM

Quote:

Originally Posted by paulatgis (Post 891131)
think about it. moores law also applies to drones and fpv. a swarm of bees (fpvs). canard design might be the way to go. let me know how your canard works out. sounds like a fun project.

Here is a easy one for your camera just follow the links to the free plans plus the build video is there http://flitetest.com/articles/mikeys...scratch-build/ It flys like a big trainer and made from dollar tree foam the same stuff i use. I was going to build one for my sons gi joe to ride in the front instead of a camera.:D joe

JetPlaneFlyer 12-06-2012 07:15 AM

Quote:

Originally Posted by paulatgis (Post 891093)
[LIST]
1) airfoil is naca 0018 semitrical.
2) blunt LE - well round as a nickel or quarter.
3)wing loading should be low - i build light but this time will put a big motor and big battery. its go 60 inch by 12 inch chord without including ailerons which is about 5 square feet. auw expected will be 5 to 6 lbs.
4) thick wing naca 0018

hows my stall characteristics looking?

The NACA 0018 is a symmetrical airfoil, not semi. Any NACA four digit airfoil who's number starts '0' has zero camber, which means symmetrical.

18% is a bit thick thick for models, it will fly but it will be very draggy.

rcers 12-06-2012 02:22 PM

Agree that is a bit too thick and will need a good deal of power and fly somewhat slow. You might be better off with a semi airfoil or even flat. :)

that would give a plan to fly slow and might work well on this first adventure.

Mike


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