crownvic

what bad things will happen if you take the fire wall and make it square with the fuse or shim the motor mount to make it straight ahead. I hate that look of the motor offset I have shimed the mount on my H9 T6 and cant really see alot of differance

Lonnie

cknaack

My Feedback: (1)

The thrust line is set in order to help the airplane fly straight. Changing it will only make it fly poorly.

Have you tried to offset your cowling to lessen the visual difference?

CheezeyPoof

A fair amount of planes already have right thrust in the fire wall. Most of World Models does. Dont know if the H9 T6 does. If so and you added to it, I could see your point. Some planes react bad with no right thrust and some do nothing. I built the Kyosho T6 and the cowl also was built in such a way as to mask the offset

DBCherry

My Feedback: (4)

It could very well make the plane fly poorly, depending on the plane and engine. It's entirely possible that ground handling would become very difficult due to torque pulling the plane dramatically to the left, or a tendency to snap on take off. You might also have to put in a lot of right rudder trim in order for the plane to fly straight.

They're designed with right, and often down thrust for a reason.
Dennis-

greenboot

My Feedback: (1)

Lonnie,
I suspect you will find very little differance with the engine squarely mounted. If the offset bothers you, I wouldn't hesitate to make it straight. I have flown some VERY crooked planes, and they still fly.

Tom

flat spin

Okay so you do need right thrust and you don't need it. I am getting confused. I have got a H9 Funtana where the Cowl and Firewall both have right thrust built in, not evident on other models which I am flying. Now I have just completed a Graupner 300 Extra with a YS 110 up front thus probably slightly over powered perhaps very much so. There is a visable slant on the Cowl to incorporate right thrust but nothing on the firewall. The engine is still centered on the Cowl so what is going on. I am planning on putting a couple of washers on the left of the engine bearer to give it some right thrust but obviously don't want to get it wrong.

Has anyone encountered a similiar problem or have any advice? From what i hear the effects of the thrust line can be quite dramatic and with so much Torque I feel this could be a real problem.

Waddya reckon

CheezeyPoof

OKay, Right thrust is not mandatory. "DB Cherry" calls it straight. Cubs and small AT6 Texans are notorious for running around in circles while trying to take off. I suggest squaring it off and fly it. If the plane track well down the runway without going nuts on you, then leave it alone.
Some planes like the Cub and smaller texans and others do circles even with right thrust. To help , take of very slow until the plane picks up speed

Remember the little Thunder Tiger Profile extras that resembled Fazers? I had one about 5 years ago. When i took off, it just went where it felt like and as long as it went in the general direction away from the pits then whenever I got speed, I took off. It was nuts . Taking off down the runway just did not happen. Once in the air it flew great

flat spin

Unfortunatley no Runway where i fly, and pretty bumpy too so you wanna get the thing in the air quick time. But okay so if it is not mandatory go with it as is and see how it fly's. The only concern i have is if it will drop a wing on take off or somthing dramatic, people talking about a snap in to the ground. do you think that is likely and surely if you got a bit of right aileron and left rudder prepared in your mind then you can counter the effect, No ?

MinnFlyer

My Feedback: (4)

Don't worry about it. You may notice a slight difference, but there's probably not anything drastic going to happen.

flat spin

Cheers Mike, I will enjoy my first flight a lot more knowing that nothing drastic is going to take place. At least not from that

DBCherry

My Feedback: (4)

Well it sounds to me like you're not use to using the rudder and if that's the case, then it's entirely possible that something "drastic" WILL happen. (Especially if you feed right aileron and LEFT rudder. [])

I don't know the wingspan or weight of that Graupner Extra, but if you think it's going to be overpowered, then I'm guessing you know it will be.

Unfortunately, rough (no) runway, trying to yank a plane off the ground, being overpowered with a four stroke, no right thrust, and not knowing how to use rudder smells like a real problem to me.

Minnflyer is usually dead on with his advice, but in this case I think he's wrong to dismiss the potential for disaster.
Dennis-

flat spin

Well the wingspan is 63" and the kit is quite heavy. The kit can take a 91 two or four stroke so with the weight of the Ys 110 being not much more than the surpass it seemed like a good bet.

I am not quite sure what the effect of this torque is going to have as it is not somthing i have really encountered before probably because all of my planes have been set up properly. I have however seen the electric guys at the field encounter serious torque effects when launching delta wings off a catapult although i am sure the effects here will not be nearly as pronounced. And I assumed that to counter the role one would use right aileron and i know left rudder i used to counter side thrust on slowing the model but i would certainly welcome any further insight you might have as to how one can counter these effects


Cheers

crownvic

the reason i asked is my new gs world models zero has alot of slant built in to it and was wondering about making it straight. what do you think?????

lonnie

DBCherry

My Feedback: (4)

lonnie,
Read my posts above.

flat spin,
You counter torque effects with RIGHT rudder, not left. Oh, and using any ailerons immediately after take off to counter torque effects will likely make the problem worse, not better.

Think about it. The plane is being twisted/rotated to the left by engine torque; what happens when you add right aileron? The left aileron drops, which increases drag on the left wing, which will cause additional yaw to the left. Just what you DON'T want.
Dennis-

flat spin

Gotcha,

I was thinking about the right thrust but of course you implement that to counter the pull to the left hence right rudder. This would also take care of the wing dipping to the left. It all makes sense now.

So the only question that remains is wheather or not to build in a bit of right thrust from the start or fly it and see how it gets on?

DBCherry

My Feedback: (4)

Well, it's easier to add right thrust than to take it out once it's built in, so I'd fly it (carefully) first.

To add right (or down) thrust, you simply add washers under the engine mount, but in front of the firewall.

Keep in mind that pretty much every kit or ARF I've seen, plans too for that matter, have been designed and or manufactured with the correct right and down thrust built in. You usually compensate for the engine offset when installing the cowl, if the plane has one.
Dennis-

flat spin

Cheers Dennis

J_R

The affects of thrust on ground handling are secondary. Usually, goundhandling problems can be attributed to the lack of tow-in of the wheels. Rudder inputs should be able to take care of the thrust affects on the ground.

Once the plane is in the air and trimmed for straight and level flight with the radio trims, you can check the thrust by (in dead air) pulling straight up. In hands off flight the plane should go straight up and not pull to one side or the other. If it does, you need to induce more thrust angle in the opposite direction. Each engine/prop combination produces a different amount of thrust. You can only get close setting it statically.

Some manufacturers will put thrust into the firewall. Usually about 3 degrees of right thrust. Some will then offset the engine to the left so that the prop shaft is then centered where it exits the cowl.

If you straighten the firewall, and install the cowl, you will probably later find that you need to induce right thrust and the engine will not exit the cowl correctly.

For more on trimming a plane, see this site: http://www.wtp.net/DBEST/trimchrt.html

AQ500

What about down thrust?

DBCherry

My Feedback: (4)

AQ,
I'd check the manufacturer's specifications. I don't know that particular model, but I'm guessing you have a degree or two too much down thrust.

When you fly it, do you have trouble with it lifting off? Does it tend to dive at full throttle? If so, then you likely have too much down thrust.

[X(][]
Dennis-