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How will it fly, what should I expect?

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How will it fly, what should I expect?

Old 01-19-2008, 05:24 PM
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daven
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Default How will it fly, what should I expect?

I scratch built this plane over the winter, loosely based on some of my ideas and that funky Blohm and Voss. I also tried to shape the fuse in roughly an airfoil type shape since these planes spend a bit of time in left side knife edge.

Just curious on what I should expect on the test flight, and if I should mix any aileron or rudder to the elevator to offset any potential yaw or rolling issues?? The plane will fly at about 110-120 mph, and needs to be able to make a 100 foot radius turn (on knife). I'm concerned about what the plane will want to do at that speed, when I use that much elevator to make that 100 foot turn.

Also, curious in regards to what it may do on take off.

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Old 01-19-2008, 06:24 PM
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Default RE: How will it fly, what should I expect?

Oddly enough you probably should have had the stabilizer on the other side. My thinking on this.... Up elevator will make it want to roll slightly to the left or more into the turn. That'll make it want to roll onto it's back and try to kiss Terra Firma. OK, so you mix in a little aileron so the left aileron is down and vice versa. But that means the left wing is producing more lift due to the aileron acting to increase the camber of the airfoil and also the angle of attack all at the same time. So the left wing is lifting more than the right. More lift brings with it more drag so the model has just exchanged rolling further into the turn for wanting to yaw towards the ground. Also you've got more drag on the left side than on the right thanks to the profile and induced drag of the stabilizer on the left. Again, it'll try to yaw towards the ground.

But if you were to put the stabilizer all or mostly on the right side and then trim in a little bit of aileron to counter the rolling couple as required then all the yawing would be helping to hold the model UP instead of trying to yaw it down. And if it was on the right it would be a tad more centered thanks to your fuselage offset so the rolling couple would be less and that means less aileron.

.... at least that's my musings on this.....
Old 01-19-2008, 06:50 PM
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Tall Paul
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Default RE: How will it fly, what should I expect?

Your single-sided horizontal is going to add a LOT of roll to the airplane when you try the elevator!
Pitch forces kinda need to be symmetrical.
I can see a nose high left roll into the ground in my mind's eye on takeoff.
Old 01-19-2008, 09:20 PM
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Campgems
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Default RE: How will it fly, what should I expect?

I probably shouldn't even respond to this as I am not that experienced, but here goes anyway. The concerns on take off I expect are very real. I have an orginal Quicke 500 that I am reparing, again. Your setup looks a lot like the quicke with the exception of the asymetrical fuselage and single sided horizontal. The quicke is difficult on take off and also on landing, but inbetween it is a ball. I expect your design will amplify these bad traits.

Get someone to take a video of the maden, I'm really interested to see what it does.

Don
Old 01-20-2008, 10:20 AM
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Lomcevak Duck
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Default RE: How will it fly, what should I expect?

I think it's going to want to yaw to the left in straight lines. Neat idea, though. Let us know how it does.
Old 01-20-2008, 11:18 AM
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Mike Connor
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Default RE: How will it fly, what should I expect?

That just doesn't look right!! I think a video of the maiden is in order.
Old 01-20-2008, 11:59 AM
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daven
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Default RE: How will it fly, what should I expect?

Campgens, it is a Q500 plane, so I know what to expect in regards to that, I'm just curious if I should attempt to mix some right aileron in with elevator to compensate for any funky rolling it wants to do when I full a hard turn in full knife edge.

Not sure I want this documented in film

Test flight will happen on a weekday with minimal people around to witness. It will be at least April before the runway has melted.
Old 01-20-2008, 12:52 PM
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Campgems
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Default RE: How will it fly, what should I expect?

One last though, if the tail causes it to yaw and you have to dial in aileron to conteract that, and maybe some extra rudder to keep it on track, isn't all the corective controls going to cause more drag and slow things down some? Seems that the cleaner you can fly the faster you can fly.

Don
Old 01-20-2008, 02:08 PM
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daven
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Default RE: How will it fly, what should I expect?

You are correct, although at these slower speeds its not as detrimental as it is at 170 mph.
Old 01-20-2008, 04:32 PM
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Mike Connor
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Default RE: How will it fly, what should I expect?


ORIGINAL: daven


Not sure I want this documented in film
Think "Funniest Home Videos" and $10,000
Old 01-20-2008, 08:37 PM
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Campgems
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Default RE: How will it fly, what should I expect?

Dave, one more thing popped up, is the horziontal stab going to be strong enough to handle the double length and all the force on one side?

One other question, where does one find the rules for the quike 500 class. I think it is 50" span and 500 sq in wing, but how about cord thickness, fuselage length and such.

Don
Old 01-20-2008, 08:45 PM
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Default RE: How will it fly, what should I expect?

Go to the AMA web site, click on Technical Info/Events. Next page has listed on left side "Competition Regulations", click again on it, Then on the next page click on "Radio Control Racing". This will open a PDF file.

Or just click on this:

http://www.modelaircraft.org/events/...C%20Racing.pdf
Old 01-20-2008, 09:07 PM
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Campgems
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Default RE: How will it fly, what should I expect?

Thanks for the link. I need to do some reading now. This talk is nudging my broken quicke up on my to do list.

Don
Old 01-21-2008, 07:36 AM
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daven
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Default RE: How will it fly, what should I expect?

My biggest concern was stiffness and rigidity in the tail section. The INSIDE of the fuse is fiberglassed (3/4 oz) it also has Carbon Laminate 3/4" strips running length wise inside the fuse.

The tail is a sandwich. Center is 3/16" balsa, capped with 1" wide carbon Laminate and a layer of 3/4oz glass. Then as the glass was wet I added 1/32" balsa on either side and placed in a vacuum bag. After that dried, I inset 1/64" ply all around the outline of the tail on the centerline of the thickness. Then shaped, and airfoiled. It is about the stiffest tail I have ever made.

The wing is 52" with a chord of 9 3/4", it meets all other AMA rules for this class.
Old 01-21-2008, 12:37 PM
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Default RE: How will it fly, what should I expect?

I would treat it like a v tail mix wise. I dont know if it is looks or something else in my mind but I think the stab would be better in the other side of the fuse.
Old 01-21-2008, 01:56 PM
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daven
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Default RE: How will it fly, what should I expect?

I put the tail on that side to offset the weight of the head of the motor (at 9 oclock). Beleive it or not, the plane would need left wing tip weight to laterally balance, which I rarely do until after I test fly a plane.
Old 01-24-2008, 12:05 PM
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Default RE: How will it fly, what should I expect?


Dave,

I would expect that the airfoil shape of the fuselage would give you some yaw, which would need to be offset by rudder trim, and would increase drag. The asymmetric horizontal stabilizer would have the same effect, but the two might partially cancel if you're lucky.

I don't know how much benefit there is to generating knife-edge lift with the fuselage. When a plane turns tight, the needed lift is generated by the wing, since the bank angle is less than 90 degrees. Generally, your wing is the most efficient lift generator on the plane, so it might be best to avoid trying to make any other surface generate more lift.

If you're willing to incorporate some assymmetry to improve performance, I would consider leaving the horizontal stabilizer centered, but put the vertical stabilizer on one end, with a nicely radiused junction. This would eliminate a few junctions, and reduce 'interference' drag. If it's structurally feasible, instead of having the fuselage continue behind the horizontal stabilizer, have it taper down to almost nothing, so that a clean horizontal stabilizer, with the asymmetric fin on one end, is the rearmost part of the plane. This would eliminate the right-angle junctions between the horizontal stabilizer and that section of the fuselage, also reducing interference drag.

It looks cool. It's good to see someone trying new stuff.

banktoturn
Old 04-24-2008, 07:02 AM
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Default RE: How will it fly, what should I expect?

I flew the plane twice last night, it was quite windy, but not too bad.

Holding a little right rudder as the plane took off and it went straight as an arrow, with a very shallow climb out. There was no roll at all with elevator and I had plenty. I was pulling 30 foot diameter loops that looked perfect, with no roll out.

The only issues I had were instability in pitch, and too much throw. I had a heck of a time landing the plane as it wanted to balloon up, the plane appears to be a bit tail heavy which I will address before its next flights. It was really too windy to tell if it had any other unusual characteristics, it basically felt like any other Q500 type plane I have flown, other than having a weird shape in the sky.
Old 04-28-2008, 09:31 AM
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Default RE: How will it fly, what should I expect?

OK,

I got in 5 more flights in the snow yesterday and worked out most of its issues, but I need some advice.

It was not pitch stability that I was fighting. When I used left aileron, the plane would act as though I gave it a good amount of down elevator at the same time. I ended up adding a 20% mix with Left Aileron being the Master and UP elevator being the Slave. This worked very good, but is obviously adding additional drag. What I found unusual, is that I have no issue with right aileron, just left. The one sided stab must be getting some turbulent air off of the left wing when I bank??

Now here is the problem, the plane is flying pretty darn good, but being a racing type plane, it spends a good deal of time in knife edge flight and straight and level. The plane flies perfectly in the straight and level, but in 90 degree knife edge to the ground, it wants to drift towards the canopy, which is not a good thing. I tried moving the CG all over (front and back), but that did little in regards to the drifting action. Normally, moving the CG back helps, but not in this case.

I'm going to verify my incidences, but I remember this being pretty darn close to 0/0/0. I suspect that I will need to adjust the incidence of either the firewall or the wing (easy), but I am not sure where to start. My thoughts that a little down thrust might help, but I'm not sure. IF that doesn't help, how about raising the LE of the wing by a 1/16" and see if that helps.

Any advice would be appreciated.

Thanks,
Old 05-02-2008, 05:46 PM
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Default RE: How will it fly, what should I expect?

Dave congratulations for your now test and flown new invented plane. I am far to be an expert but I think that some incidences have to be adjusted. You can start with the engine incidence as this is the easiest way (install some washers between the firewall and the engine mount).
Have you made some verticals?
Does your plane goes stright up?
How does it fly inverted?
Good luck and happy landings.
Old 05-03-2008, 10:02 AM
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Default RE: How will it fly, what should I expect?

You might try flying with the right aileron active only. You might get rid of the mix. I know you wont normally fly the plane this way but try flying right hand circuits to see if the pull is different and how effencent the fuse is.
Old 05-03-2008, 09:20 PM
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daven
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Default RE: How will it fly, what should I expect?

Alfred, I never attempted verticals or inverted flight, I normally trim racing type planes to fly like they will on a racing course, but I will give it a try tomorrow, as well as add a bit of down thrust and see if that helps. Its really not that bad, just an annoying trait for racing when you are flying around yourself.

This plane will go up till it is out of sight, its doing about 110 mph now, and with an engine change will be up to 125 shortly. Just want to get the quirks figured out.

TFF, good point about the right aileron. The wing I am using now (Viper ARF) has very small ailerons, I'm not sure I would be able to get by with just one, but thats a great idea for the next one. I'll also try a clockwise pattern to see if it acts differently.

Thanks to both for your thoughts. I'm just glad it flies, and even more glad that it flies better than expected.
Old 06-08-2008, 02:57 PM
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Default RE: How will it fly, what should I expect?

As I was reading, I had the same idea as TFF... use the right aileron only. The upward deflecting aileron during left roll is lifting airflow off of the stab, changing the effective angle of attack of the horizontal stabilizer during the left roll.

You might try building an aileron with a little more chord... but I'd think you may not need to. Fly it single aileron first, and go from there. Is there any way you can mechanically lock the aileron in the "trailing" position... you might just be able to do it with a mix, just for testing purposes... in fact, that's exactly what I'd do... set up Right aileron as master, left aileron as slave, assign it to a switch so you can turn the left aileron On or Off in flight...

Neat project, great "Out of the box" thinking!!

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