bh tornado no take off just taxis

[crispin church]

given a black horse tornado high

it just will not take off got loads of throw all going right way loads of power

when and only happen once or twice for the last owner it takes off then goes straight and its a fight to level out before stall then it flys fine no probs

tried increased angle on rear tail ie wedge at front to give straight fin with prop flow

any ideas please

[Chris Bott - Moderator]

Crispin, it sounds like the model is eiher not reaching a high enough airspeed, or isn't acheiving the angle of attack the wing needs.

Could you try a larger nosewheel? or smaller mainwheels?

Is the C/G in the correct position, if that's a long way forward you might get the same problems.

[Tim Cheal]

Is it overweight?

Tim

[Philip Ogden]

Assuming you have enough power and the cg is within limits, the aircraft should fly. Check the main wheels are not too far back, if you push down on the fin, the model should rotate on the main wheels with very little effort. If you have to apply a lot of force, that will suggest the problem. Also, if you have a small nosewheel and large mainwheels, this could put the wing at a negative angle of attack making rotation diificult.

[PatMc]

Even if the cg is correct, if the main wheels are too far behind the cg the model can have difficulty raising the nose to get a positive AoA. This means that when the nose does rise it jerks up & the model will tend to leap off the ground in a semi-stalled condition.

With the cg as recommended & the model on a level surface pushing the tail down should take very little pressure, in fact without fuel it should almost balance on the main wheels.

Personaly I don't like trike U/C on models, I'd remove the nose wheel & angle the mains to be level with the wing LE.

I'm a slow typist, Philip has said much the same.

Edited By PatMc on 20/09/2013 23:30:16

[Bob Cotsford]

As has been said, if it flies ok then it's either the mainwheels too far back compared to the balance point or it's got a negative angle of attack on the ground.

Sitting on it's wheels it shouldn't take much effort to push the tail down to the ground, and it should only just rotate back onto the nosewheel when you let go. As it's an ARTF I would expect the mains to be in the right place so this will more likely be caused by the CofG being too far forward.

If you sit it on level ground and measure the height of the leading and trailing edge they should be equal or the LE should be no more than 1/4" lower on an average size model. Any more and it will not rotate easily for take-off, if the LE is higher than the TE then you will risk getting bouncy landings.

All this supposes that the engine actually has enough guts to accelerate the model up to flying speed on the ground! It's a 60"ish span model with a weight shown as 2.6Kg, around 5 3/4lb - to me that sounds like a big model for a .40, more like the .46 end of the suggested range or even up to a .60.

[crispin church]

VERY SORRY MY BAD

its been converted to tail dragger

its now electric did have irvine 53 and still would not take off

conpaired to my cap the tail slope wrong way

cog is right on  and is lighter than advertise weight 

main wheels just infront of wing

 

Edited By crispin church on 21/09/2013 09:43:02

Edited By crispin church on 21/09/2013 09:44:19

[Biggles' Elder Brother - Moderator]

Posted by crispin church on 21/09/2013 09:41:51:

 

conpaired to my cap the tail slope wrong way

 

Hi Crispin, can you explain that a bit more - its not clear what you mean.

Are you saying that the tailplane is angled up at the back on the ground?!!!

BEB

PS Can you post a photo of the model up?

Edited By Biggles' Elder Brother - Moderator on 21/09/2013 09:57:07

[john melia 1]

can you get a video of it Crispin

[Chris Bott - Moderator]

As a tail dragger, does the tail sit nice and low Crispin?

If the tail leg and wheel hold the tail up, and this keeps the wing level, you can have this problem, the tail needs to be very low so you can take off.

[Pete B]

Crispin, it sounds to me as if having changed from trike to taildragger, the wheels have been set too far forward. You say it has plenty of power. Perhaps it is being dragged into the air on power alone and the AoA is too much, thus you have to get the nose down to prevent a stall.

Try moving the wheels back a tad, perhaps?

Pete

[Biggles' Elder Brother - Moderator]

It seems to me there are two possible explainations that expain Crispin's observations:

1. The tailwheel is far too high relative to the mains: this would make rotation all but impossible. As you shove in more and more elevator and speed eventually the elevator drags it off the ground, it immediately goes very high AoA (due to the excessive elevator) and stalls. The only way of coping in flight is to release the elevator quickly and try to level off.

2. The tail wheel is far too low relative to the mains - so in a three point position the wing is already passed the critical AoA and so is in a stalled position on the ground. With enough throttle the engine will eventually pull the model into the air - still stalled. You have to get the nose down PDQ to restore controlled flight.

Both of those explain the behaviour described - but without a picture its impossible to say which is the more likley!

BEB

Edited By Biggles' Elder Brother - Moderator on 21/09/2013 11:13:45

[crispin church]

i will get photos done next week and some shots of other plane i have that are as spec

[crispin church]

compared to a piper cub sat on ground on the wheels the tail has 7degrees difference cub 10 tornado 3

wing on cub 18 degree and tornado 8

i am going to try higher wheels which will give it a 8 degree tail angle and 15 degree wing angle and try that tomorrow all being good

there is some photos in link as well

**LINK**

[PatMc]

I think blaming the undercarriage is a red herring. Lack of power is more likely.
What's the power taken in Watts, size of prop & the model weight ?

[crispin church]

2 kg 400 watt 14x7e

now gone to webra 61 on 11x8

will try that next week

[Stevo]

Crispin - Deja Vu!!!

I had one of these. 53FS up front, and it needed 3 miles of runway before it thought about becoming unstuck.

Changed it for a 56 2S, marginally better but no where near right. I did exactly what you did... converted it to a tail dragger. Guess what - NO DIFFERENCE.

Even in the air it was a right handful and went all wobbly at lower speed, indicating an aft CG. After so many attempts, it was way out over the far side of the field went nose high attitude, was a right wotsit to bring it back.. it was on full chat too. I stuffed it into the long grass, and wrote it off. Good riddance. Soldiering on, I got a Blackhorse Canter. Excellent aircraft. Flies all day on a 53FS, and takes off in 20' or so.

Shame, blackhorse models have always been excellent.

 

Not sure what it is about the Tornado though. I would never recommend it to anyone!

Edited By Stevo on 25/09/2013 08:41:07

Edited By Stevo on 25/09/2013 08:42:07

[crispin church]

well with the webra .61 on front no problems with or without flaps all good need to low throws

many thanks for all help

[Martin Harris - Moderator]

Might be a camera angle thing but there seems to be a lot of downthrust...

 

BTW BEB, did you really mean this:

"As you shove in more and more elevator and speed eventually the elevator drags it off the ground"

If the tail is on the ground, surely there won't be any affect (other than increased drag) however hard you pull the elevator?

Isn't it more a case of hitting a handy bump or (as you stated) simply accelerating to a point where enough lift is produced at the limited angle of attack? Of course, as soon as this happens, the excess elevator produces a rapid rotation and either a zoom climb or a stall - or both!

Edited By Martin Harris on 02/10/2013 08:57:33

[SkippyUK]

Is it a visual effect or is there very little AoA on main wing relative to ground and tail axis?

Surely this would make the plane very unresponsive as the tail will always be fighting to give the main wing the AoA it needs to get enough lift even in the air.

No expert like BEB and Co but it don't look right to me.

Skippy

[Martin Harris - Moderator]

Posted by SkippyUK on 02/10/2013 21:25:49:

Is it a visual effect or is there very little AoA on main wing relative to ground and tail axis?

Surely this would make the plane very unresponsive as the tail will always be fighting to give the main wing the AoA it needs to get enough lift even in the air.

 

I can't think why the wing and tail incidences would have been changed by the conversion work done (however the firewall looks like an add-on)

I flew one of these fairly recently (and also used it for several flights as a substitute trainer - long story) and don't recall it having any untoward flying characteristics in standard form.

Edited By Martin Harris on 02/10/2013 21:48:21

[crispin church]

in the photos to get cog right without lead i add a box on front that the battery fitted and motor on front this got cog right without lead

the wing aoa is very little

with webra on the old firewall its a dream to fly still needs most of our patch to take off but it takes off without any sudden change of pitch

now a very good high wing

[Martin Harris - Moderator]

Did you check the downthrust on the electric set-up Crispin?

[Frank Skilbeck]

Webra 61 = >1000 watts

Original electric set up 400 watts, 90 watts/lb (2kg model)

I think that lack or umpf was the cause of the problems

[crispin church]

i was hoping a bit on a 3 cell but would of fought it would show some sign of lift

all i can say my mate irvine 53 must be a lot lower on power than my webra