RITTMEISTER

I have 4 small Fokker D-7 kits A 16 in.span , 17.5 in. span( 1/20 SCALE) ,18. in span. and 24in span. All 4 have very small rudders and no ailerons. All 4 are designed for rubber power free flight. I want to install radio and electric power.
Do these planes need ailerons? or will rudder/elevator/engine be enough to fly and land?(Rudders are very small maybe to small to be effective)

RITTMEISTER

Mode One

Only guessing here. I think this would work with an increase in the model's dihedral. The DVII had no real dihedral in the upper wing. Not a small plane guy, I would suggest going to aerodynamics and asking about this. Only answered because there didn't seem to be anyone with an opinion. I should think a few degrees of dihedral would be all that was needed.

TLH101

My Feedback: (90)

A freind built a small indoor electric D-7 a couple of years ago, with no ailerons, and no dihedral. Did not fly well. Would not turn. I don't think it will look right with dihedral, so I would use ailerons as well as rudder.

RITTMEISTER

Mode One,
Thanks for the info. The Dihedral will assist in lift and I think allow more air to the rudder allowing it to function better. The Rudder being so small.
RITT

RITTMEISTER

TLH101,
The original Fokker D-7 had a flat upper wing. For r/c models most have a little Dihedral so the upper wing does not appear to sag, and to assist the air flow to the rudder. I really want ailerons but the weight and the amount of space
would make it a challenge.Servos would have to be mounted externally. I happened to find 2 videos with very small Fokkers and elevator and rudder only with much success.
RITT

MajorTomski

Actually if you really really want to get nitpicky the 1:1 D-VII has a very slight amount of anheadral in both the upper and lower wings. Like less than one degree.

Diheadral has absolutely nothing to do with increasing lift or allowing more air to reach the rudder.

Other individuals who've built small D-VIIs indicate that it needs both rudder and aileron in a coordinated effort to turn well.

RITTMEISTER

The other small Fokker D-7 kits you are refering to have the aileron servo or servos mounted externally?? Wings are thin. Ailerons are an option even on 1/20 scale or a little bigger?
RITT

Mode One

I disagree with Major Tomski, The DVII actually had no dihedral, or annihedral. The center line of the wing ribs was flat, however, the wing ribs grew smaller as they went out to the tips producing a taper wing. So, the top surface of the wing tappered down and the bottom surface tapered up. This per my Squadran Signals book on the DVII and other drawings I have.

Dihedral in aileron-less airplanes is in effect ailerons. It doesn't increase lift and doesn't allow more air to get to the rudder. In a left rudder turn, the rudder yaws the airplane's nose to the left. When yawed, the dihedraled wing shows more of the underside of the right wing to the slip stream and shows more surface of the top of the left wing to the slip stream, causing a rolling moment. Dihedral is also used to produce lateral stability. R/C Sailplanes with out ailerons use dihedral to roll into turns. Free flight models use dihedral to stabilize the roll (lateral) axis.

Scott G

I have the Great Planes electric DVII and find that it turns best using coordinated rudder and ailerons. Once the turn is started I hold in enough rudder to keep the turn going and feed in opposite aileron to keep the bank angle constant. If your little ones fly the same you may find that the best solution is to have ailerons and rudder.

Scott.

Mode One

Adding an aileron servo will increase weight, something I can understand Rittmeister being concerned about, with these small airplanes.

RITTMEISTER

Mode One,
Wow!! Thanks for the the info . Very smart and very helpful to myself/others!!
Ritt

RITTMEISTER

Scott G,
What is the wing span on your Fokker??
Ritt

RITTMEISTER

Mode One,
You mean I need to add a good ammount of dihedral if rudder/elevator only?? How about downthrust on E motor??
RITT

Scott G

It's 36" inches. Here is a link:

[link]http://www.electrifly.com/largeelectrics/gpma1141.html[/link]

Scott

Mode One

Ritt, Your getting into the realm of aerodynamics. People whom fly small R-E airplanes would know more about this, then I do. You stated that the airplanes are designed for free flight, do they have some dihedral in them?

At 36 inch wingspan, the Great Planes E-Fokker DVII is large enough to carry a micro aileron servo, so is in a completly different league.

RITTMEISTER

MODEONE,
The small Fokker D-7 wing span is 16 in. no dihedral.... the next one is 17.5 in. span no dihedral, and 18 in no dihedral.( the 24 in span still in the box has 1/4 in dihedral on plans) I just completed A Dare design Fokker D -7 36 span E power. I added ailerons,increased the dihedral to 1/2 inches,and installed micro servos in each wing on that one. .Build weight was supposed to be 18.3 oz. Well flying weight was 27 oz!! I built it to stand the test of time instead of building it to FLY! Downthrust??
[:@] RITT

Mode One

I would use 2-3 degrees of down thrust. However, I would think this to be easy to adjust with an electric set-up. If not, I would make it so it was.

There are so many variables; Could you build the airplane with ailerons and elevator and no rudder? Why have you added dihedral to the airplane that has ailerons? If the one has 1/2 inch of dihedral, a similar angle of dihedrral may work for all. Notice I said angle and not 1/2 inch. 1/2 inch on a small airplane is considerably more dihedral then a bigger one.

Hope this is helpful!

RITTMEISTER

Good question.....why dihedral when added ailerons?? I got advise that now seems inadequate.Too late on the DARE kit I am installing geared motor now
HMNNNN on the no rudder?? Explain. I guess I should have been flying gliders in the 70s instead of watching them. I only could afford controll line. I am still learning and I really thank you for your advise!
RITT

Mode One

With R/C model airplanes in flight, aileron and elevator basically provide all the control needed. On the ground, rudder is more necessary. If hand launching you could get by without rudder. I guess the ideal would be rudder and elevator with the proper dihedral to provide roll for banking in turns. "Proper" being the operative word. This set up allows control both on the ground and in the air.

MajorTomski

And that tapering down, on the upper surface, by definition is anheadral.

Bruno Stachel

My Feedback: (4)

Never mind.[&:]

Bruno Stachel

My Feedback: (4)

Never mind.

Bruno Stachel

My Feedback: (4)

[&:]

Mode One

And, my opinion is; By definition the dihedral or annihedral of a wing deals with the geometric planes of two wing halves (these are planes described as starting at the tips of the leading edges, going to the tips of trailing edges and from the roots to the tips of both wings and creating an upward or downward angle measured at the roots of both wings).

I have my point of view and expect you have yours.

RITTMEISTER

ModeOne,
please forgive me my 2 sons and I (7 kids) have put the 3 sets of plans on building boards and all 3 have 1/2 "dihedral!! so stick with that no ailerons?? again forgive me for that! 2 smaller ones have dihedral in both wings the larger one only has dihedral in the lower????? crazy
RITT