Abnormal sailplane mod idea...is it feasable??

[Mchone, Jake]

Hey!

After my Ascent sparked the old thermaling spirit after a sinful winter full of powered flight I desided to get to work re-building my old croumpled and bashed Aspire 2meter.

I have re-built and fixed the wing already and started stripping my old fuse for parts for the new one and I desided to keep the old tail feathers...just in case ;) and thats when It hit me!

Could I cut the old horizontal in 1/2 and make a V-tail'ed Aspire?!? :cool: :rolleyes:

Im already re-covering it in the origional trim scheme but in transparant orange or green (I still havent desided which would be the most all around visible) becasue I want something different than the light blue and deffinatly not the light violet the EP version is covered in! So what could be more origional and different than a V-tail'ed 2M floater?? :rolleyes: I've certanly never seen one before! :D

But would it be feasable?? Would I still have good stability and controle?
Would I need to inlarge the area of the elevon from the stock elevator area?
What about the angle? What would it need to be?

Also, I dont want to tear apart my new tail just to get the epoxied tail feathers off. So could I use my old tail to mount the V-tail onto and make a removable tail?!? :confused:

I know it would need to be very stiff and not move, so how should it be mounted?? How could I mount it with screws and blind nuts because it would be hard to find a 2ft long screw driver! :p

Is that feasable at all??
I need help with some mounting ideas before I start pulling my hair out!! :eek:

ANY help, ideas, constructive critizism, or comments would be VERY much appreciated in my "Out-Of-The-Box" quest for an origional and surprizing 2meter floater! :)

Thanks
-Jake

[flystoolow]

Of course it will work. Just make sure the whole area of the V-tail is close to the whole area of the standard tail surfaces, stab and fin. Also increase the overall width (cord) of the moving surfaces to increase control. It most likely won't work any better (probably slightly worse in fact), but it would be fun. 100 degrees will suit the angle. Mounting ideas...I think a little glue might just work.

Good luck. :)

[tw126a]

I have a Midwest Essence 2 meter and it can be built both ways. I believe the V-tail is set at 110 degrees with a somewhat enlarged surface area.

Tom

[MTT]

Yes, it will work, only problem might be, that your v-tail would be a little on the small side.
So you would have a little less built-in longitudinal stability, which in the case of the Aspire, probably won't be a problem.

Rule of thumb for V-tails :
Their size should be such, that the projected area is equal to the area of the normal horiz. stab.

[Ollie]

"Could I cut the old horizontal in 1/2 and make a V-tail'ed Aspire?"

If you use it, you must use a longer fuselage. The tail moment length will be about 3 feet.

"Would I still have good stability and controle?"

Yes, if the fuselage length is about 12 inches longer than the tail moment length.
The problem is making the fuselage long, strong, stiff and light weight. You must skills of the fuselage structure designer.

"I know it would need to be very stiff and not move, so how should it be mounted?? How could I mount it with screws and blind nuts because it would be hard to find a 2ft long screw driver!"

First you must build up your skills by studying the plans of good V-tail R/C glider designers.

"What about the angle?"

About 105 to 110 degrees between the tail.

Also, the radio or a mechanical device must have mixing for the V-tail.

[rdwoebke]

Jake,

Do you ever fly with the Lexington club?

[Bernd Brunner]

Jake, build a new one similar to the old one but a bit larger as MTT has described.

Take a look on the removable v-tail we have build for our MERLIN. we have CA´d a thin plate of plywood (1mm) onto the fuse and filled the gap with microballon-epoxi. On the bottom of the v-tail we have glued a second plate.
On the top-side of the v-tail we filled in balsa. A blind nut was added here. The screw (3mm) comes from the bottom side of the fuse. Look at the pictures.

Bernd

Merlin: http://www.rcgroups.com/forums/showthread.php?t=297265

[markdrela]

Rule of thumb for V-tails :
Their size should be such, that the projected area is equal to the area of the normal horiz. stab.
This rule of thumb is plain wrong. To get the same stabilizing effect, the projected vertical and horizontal areas of a V-tail must be significantly larger than the areas of the equivalent cross-tail. For V-tail conversion relations, see here:
http://www.charlesriverrc.org/articles/design/markdrela_vtailsizing.htm

At a CRCC RES contest some years ago, I saw an Aspire with a V-tail. It was simply the stock Aspire horizontal stab, cut in half and mounted at some 30-35 degree dihedral angle. This tail was grossly inadequate, especially in yaw, ultimately causing the destruction of the glider. The glider was stalled during a winch launch, shortly after the throw. Normally this would result in a nose-down dip with perhaps a minor veer, and the climb would continue. But here the very low yaw stability allowed it to rapidly veer 180 degrees and plow into the ground under high line tension. The results weren't pretty.

[FWFlyer]

I have a kit-bashed Skimmer 400. My flying buddy and I liked the easy thermal ability of the plane, but we disliked the handling. So in a new build, the wing was made polyhedral instead of straight dihedral. Also, the standard R/E configuration was replaced with a V-tail.

The V-tail is probably a bit small as it is only 20% larger than the original elevator. But we wanted to keep the tail light for better balance and less nose weight.

The fuselage is stock. No lengthening was done. Handling is good.

Basically, I am saying, "Go for it". It is a doable proposition.

[Mchone, Jake]

Thanks alot fo rall the responces!

I just got back from the shop with my new covering and servos(going with a darker blue sence they didnt have any transparent colors other than red, which is what my Ascent is covered in and I dont need another red barron :p

So If I do it, I assume the stock horizonals wont work well enough so I'll have to make new ones...that part I dont like becasue I just spent 60 bucks on it and havent even baught an Rx yet and I still need to eat :p So I think i'll put this on the back burner untill I get a buddie's plane done for our fly it in July.
But keep all the suggestions comming!
I'll do it asap, but with the amount of work on that model, I have to get it finished first!

Also, I think a few of you got my idea a little back wards.. Im not having trouble mounting the V, But I'd like to make a removable tail, so I could use both the convencional tail, AND the V-tail by sliding on and off a few inches of the tail.
That Is the mounting problem I was talkign about, not gluing on the V its self.

Also, I dont want to tear apart my new tail just to get the epoxied tail feathers off. So could I use my old tail to mount the V-tail onto and make a removable tail?!?

I know it would need to be very stiff and not move, so how should it be mounted?? How could I mount it with screws and blind nuts because it would be hard to find a 2ft long screw driver!

Is that feasable at all??
I need help with some mounting ideas before I start pulling my hair out!!


Yes, I do have a mixer for it I used on soem old V-tail desighns(im no noob to V-tails)

rdwoebke,
Sorry, no, I never get to fly in Lexington, my car just wouldnt make it :p

Im off to go do a lil' math to get the area of the old tail and start drawing some new desighns for when im able to grab some balsa abd get to cutting!

Thanks guys and keep the help comming! I'd realy like this to work :)
-Jake

[Mchone, Jake]

Ok, I did some measuring and finaly got myself to do math for the first time sence the end of school :p

The Vertical area on my Aspire's stock tail is aprox. 40 sq. in. in cluding rudder
The Horizontal(including elevator area) is aprox. 104sq. in.

So the toal area is 144sq. in. total stablizing area, so I would need to desighn the tail to be very close to the 144sq. in., right??

Well I did. I layed out the old half of the horizontal stabe and measured out 1 inch form every side and angle to make it larger and it came out to have ~85 sq. in. of area(remember, its 1/2 of the hor.) and that ives me, for the full V, 170sq. in. of area, which is about 10 to 20% bigger in area than the origional, which is what would be best right??

Are all my calculations right?
Is the 170sq. in. better than the old 144sq. in. sence its a V? Or do I need to make it a little smaller to be closer to the origional area so it won't 'weather vain' in windyer conditions...

If all this is right, the next time im at the shop i'll pick up some balsa and get to cutting! :D