Tee Dee Performance Crank

1/2A Nut wrote:
Spin, spiral ie 360 deg rotation on center axis we are not clear as what he is describing yet fundamentally planes with dihedral (V configuration) are more prone to flat spinning even more so with a rearward CG.  

It was in a distance but I saw it spiral with nose down, basically spinning around one tip of the wing, with no reaction to any elevator/rudder command. The engine was already off.

Do you think there was any chance of locked in rudder thru interference or range issue?

Note which direction it has spiraled and see if there is a repeat should this happen again after the CG fix.
I tend to try and twist the wing panels some, shrink the newly created wrinkles in the covering to hold the twist with built up wings, but with iron on covering on solid balsa sheet wings there is less to work with.

If you watch the video, it looks like the plane has a definite pitch problem, you can see it climb and dive, climb and dive, with pilot control.
Get the CG about 25% back from leading edge, add lead to the nose if you have, but get the CG correct.
Also use a tri-square and set plane on flat table measure height of leading and trailing edge of wing and horizontal stab, is stab parallel to wing? A little positive incidence, but not much over a couple degrees.
The plane seemed to have plenty of power, get'er trimmed and have fun!

1/2A Nut wrote:Yes as mentioned I did weight checks with a throttle sleeve and prop installed vs the RC .051 and prop since he plans to use a throttle sleeve. =)

Spin, spiral ie 360 deg rotation on center axis we are not clear as what he is describing yet fundamentally planes with dihedral (V configuration) are more prone to flat spinning even more so with a rearward CG.  

If you can increase running engines nitromethane enriched fuel intake at speed you may be rewarded with more rpm. Having fuel /air induction thru a forward facing venturi has an oxygen intake advantage allowing more fuel if made available thru pressure. Some RC car guys are using micro size turbo's and blowers where as we have speeding planes bored out venturi's and fuel pressure  



http://www.rbinnovations.com/

I'm gonna have to cry foul on that video. As Elvis said "A little less conversation and a little more action"

I was hoping to see that thing tear up the road!!!

Mark Boesen wrote:If you watch the video, it looks like the plane has a definite pitch problem, you can see it climb and dive, climb and dive, with pilot control.
Get the CG about 25% back from leading edge, add lead to the nose if you have, but get the CG correct.
Also use a tri-square and set plane on flat table measure height of leading and trailing edge of wing and horizontal stab, is stab parallel to wing? A little positive incidence, but not much over a couple degrees.
The plane seemed to have plenty of power, get'er trimmed and have fun!

I guess I may have an isue with the  wing cord which is not quite parallel with the horizontal stab. This inclines a bit upward towards the leading edge.

I will sink the wing trail edge section more into the fuse to reduce the positive incidence.

1/2A Nut wrote:Do you think there was any chance of locked in rudder thru interference or range issue?

Note which direction it has spiraled and see if there is a repeat should this happen again after the CG fix.
I tend to try and twist the wing panels some, shrink the newly created wrinkles in the covering to hold the twist with built up wings, but with iron on covering on solid balsa sheet wings there is less to work with.

No, I found the controils in good order. Also, no sanded-in twist in the wing panels.. These issues would have caused, I guess, the plane to fly erratically breakinhg into turns right or left, with even with the engine running, but I noticed no other problem than the constant climb i.e. I assume this may be a combination of CG and wing incidence problem.

If you have a rearward CG it will pitch up and down you took off with up trim I can see it in the pic you posted. Im sure you had been pushing the elevator down letting off some pushing down again on the sticks trying to wrestle with it as you couldn't reach over to dial in trim as previously mentioned. If been there before and had a helping hand dial in a few clicks of down for me. When you are in this state simply throttle down some and it won't be climbing up slowing down enough for you to trim your plane.

I would get the CG right and adjust the trim first. 1 step at a time the AOA didn't look bad. You don't seem to have any engine down thrust that will cause conflict. Don't butcher the wing saddle yet.

Can you take a nice level side view pic?

1/2A Nut wrote:If you have a rearward CG it will pitch up and down you took off with up trim I can see it in the pic you posted. I would get the CG right and adjust the trim first. 1 step at a time the AOA didn't look bad. You don't seem to have any engine down thrust that will cause conflict. Don't butcher the wing saddle yet.

Can you take a nice level side view pic?

Thanks,


will do as proposed I am also hesitating to butcher the fuse. I am in Germany now but will send a photo when I hit home tonight.
I would be reluctant to add lead fill to the front because of the extra weight/reduced speed but will consider if mnecessary...

Typically you want a tad engine down thrust when under power and about 2 to 3 degs positive angle of attack with solid plank type wings. I also like longer tail moments with plank wings to help keep them tame if not then larger horizontal stabs to help keep the thin airfoil wing from being pitchy. If you just round the leading edge and don't sand in a full airfoil then they tend to be more pitchy. All this can be fixed with a solid forward CG when full of fuel. Typically acro planes fly between 25 to 30% off the leading edge of the wing.
I would strive for 20% when fueled.

You could do some test glides in soft tall grass to check trims. If you adjust cg and trims for a nice glide straight and level once you fire up the engine if no down thrust it should climb some. You may find when under power you have 2 clicks down and when powered off a few clicks up. Also your rates can be adjusted to suit such as low rates under full power.

1/2A Nut wrote:If you have a rearward CG it will pitch up and down you took off with up trim I can see it in the pic you posted. Im sure you had been pushing the elevator down letting off some pushing down again on the sticks trying to wrestle with it as you couldn't reach over to dial in trim as previously mentioned. If been there before and had a helping hand dial in a few clicks of down for me. When you are in this state simply throttle down some and it won't be climbing up slowing down enough for you to trim your plane.

I would get the CG right and adjust the trim first. 1 step at a time the AOA didn't look bad. You don't seem to have any engine down thrust that will cause conflict. Don't butcher the wing saddle yet.

Can you take a nice level side view pic?

Instead of a side view pic I sketched the dimensions I just measured, and here is the sketch. I calculated that the angle of incidence - at least the way I interprete what it is - is 1,86 degree...I am not sure if it is too  much, but do not suppose so.
Coversely, the CG is at about midway the wing cord i.e. 50% so I guess this needs to be relocated a bit forward by adding some weight to the nose...I was hoping not to have to do that...

What is your opinion finally?

CG needs to go forward, there is no way around that.

The wing incidence seems a little high, to me. You can have the bottom of the airfoil parallel to the stabilizer (i.e. 0° in your figure instead of 1.86°), you shouldn't need more than that. The real angle of attack is then not zero, but likely somewhere around 2° or so.

50% CG is very bad need 25% from leading edge. 1.86 degrees is just fine simply adjust your CG and trim your elevator in flight and you will have a tame plane.

Surfer Kris, 1/2A Nut, thanks a lot..I will do the mods and let you know of the results.

1 adjustment at a time between flight tests

1/2A Nut wrote:1 adjustment at a time between flight tests

Sure..I guess you meant the CG off the leading edge by 20% of the wind-cord length when the nose-mounted tank is full?

The readers of this topic may have realized that this evolved from a TD crank discussion into a building thread...I hope the plentiful information that the replies from 1/2A Nut, Surfer Kris , Mark Bosen and others carried - whom I again thank for the help - will be appreciated notwithstanding the detour from the original topic.

1/2A Nut wrote:50% CG is very bad need 25% from leading edge. 1.86 degrees is just fine simply adjust your CG and trim your elevator in flight and you will have a tame plane.

Lol yes its of no matter now as results had been carried through with the crank testing.

Yes off leading edge per the last two photo's I posted. Your next flight should be more rewarding!

20-25% from leading edge with tank empty...like its going to be when your landing!

Remember the farther forward the weight the less you'll need and don't worry a small amount is not really going to change anything other then having a plane that flies well. I think Bernie had at one time some heavy hubs Cox used on the AT-6 and a Star Wars plane.
Probably the easiest would be to attach lead to the firewall or add a 1/4" fire wall and bring the whole powerplant out forward?

I am having a new set of AAA batteries soldered in series for 4.8 volts and 800mAh and tucked under the baloon tank in the nose thus the extra weight will not only advance the cg position but also add practical value.

Those are big batteries for 3 micro servos how much does it weigh?

I measured round about 30 grams = 1oz for the 4 altogether...I need about 40 grams to balance the plane, put in the nose...so the AAA battery weight is in the right ballpark

Ok great! Does that make it happen with the lighter 049 with a throttle sleeve?

I just got a digital scale and in fact the battery weighs 52gramms so it should also suffice for the 049 with throttle ring.