DG 1000 trouble

[kiwi g]

Ian ,

Interesting thread and ideas here

But are you sure its not a simple issue such as this .

Im sure your experianced enough to know but ive seen good power flyers fall into the following.

can I ask if test flight was done with power , my reason is simple ,

when under power the model pulls along and climbs nice, one will trim for this and all seems fine as any other powered aircraft. , hence as said COG seems correct , but when you the decrease in power the wing dropped , I myself was wondering if its just a simple transitional problem from power to glider , with power and elevator trimmed there would be lots of pull and response , less power but still plenty of speed the elevator becomes less responsive, less prop airflow to the stage of being almost non reponsive.so a alieron turn is fine as long as the elevator wasnt required.

 

Watch beginners with powered gliders , quite often they trim for glide but added power causes extreme flight patterns and climb, ( it is a pilot issue usually,to rough with the sticks at power ) trim the opposite to this and power flight is good , but glide response is usless.

 

Just a thought , shame i like the dg1000..

 

[Ian Jones]

Posted by tom wright 2 on 17/04/2011 02:43:15:

Ian.

I am old school ,very old school,do you know what that is in old English? like oz per sq ft,

 

TOM.

Erm actually Tom, my school must have been living in the same era as yours. I'll sort out a conversion,.... somehow

 

Ian

 

[Ian Jones]

I don't beleive this, twice I've typed out a very long summing up and twice it's just disappeared.

 

Going off to do it in word and paste it in.

[Tom Wright 2]

Posted by Ian Jones on 22/04/2011 23:36:44:

I don't believe this, twice I've typed out a very long summing up and twice it's just disappeared.

 

Going off to do it in word and paste it in.

Hi Ian.

Did you loose the text after referring to a previous page?

 

TW2

[Ian Jones]

Right time to try and catch up again. Last time the page refreshed without asking and wiped all my hard thought out text, several times.

Rather than try and reply to the backlog individually I’ll try and cover everything here and thank TW2, Doug Ireland, Stefan Hafner, Ken Anderson, Stuart Eggerton (I watched the video by following the URL) & kiwi g for their contributions:

• Pilot errors – in the absence of proof to contrary it has to be the favourite. As always though the pilot suspects it was something else :
• Stall – could have been but if it was it was at high speed in straight and level flight – I had turned into wind and established straight and level flight intending to slow down and trim it for the glide – but the instant I took the power off the wing dropped, there was no visible change in speed before it dropped.
• Insufficient speed for the model type – seems like a distinct possibility. I’ll have to make my safe height safer next time. Hmm, high speed landings eh? Okay – with a bit of luck I won’t have to land until I’ve had chance to discover it’s stall characteristics. TW2’s comment “I think when all said and done the DG just stalls at a higher speed than you anticipated no more complicated than that” may well be right.
• Only used to “floaters” – Nah, I’ll fly anything that has wings, except DG1000! A fair point though and indeed it’s true that having seen one of these fly just once before I wasn’t expecting any problems with the glide.
• Trimming errors – Understood but I didn’t get to trim it, as far as it went I had been flying it “on the sticks”. Trimming was what I intended to do at reduced power so that I could trim for in-between glide & power as a starting point.
• Build errors – a few good points raised that I will investigate:
• CG – well I usually get this right but it will definitely be on the high scrutiny list for the re-build
• Wing twist – Oh dear. The incidence pins didn’t line up with the holes very well and I had to sort that out. I paid attention to keeping the left & right wing incidences matched but could I have got it wrong. Thanks gents, that’s another point for intensive care in the rebuild. (I won’t be able to check if this is the cause because of the damage to the pin holes).
• Winglets – they were a pig to get right and one has been knocked off – any thoughts on how useful they are
• Servo problems – unlikely. This was the one and only flight and all servos were checked before and after. The flight was more unpredictable than erratic so glitching though possible is probably lower down the blame list.
• Inappropriate use – unfortunately, from the comments made here, I fear this is the truth of the matter – I wanted a thermal soarer and what I’ve got is slope soarer.
• Adverse yaw – interesting. I did not have any rudder coupling but the incident didn’t occur in a turn. I normally deal with adverse yaw by putting in my own rudder movements as required. I fly a biplane regularly so use of all surfaces combined with throttle are not new to me and for that reason it is also unlikely that I inadvertently put in rudder movement when closing the throttle down. Still, mustn’t totally dismiss the idea, any suggestion how much aileron differential to apply

Continued...

Edited By Ian Jones on 24/04/2011 01:04:00

[Ian Jones]

• Turbulators – hmm, yes I think I have a basic understanding of this – but where to start
• Exponential – yep, I think I’ll have some that for the next flight.
• 28.5 dm2 – 442 Sq. in. wing loading about 13.5 oz/sq. ft.

In the first instance I need to get it flyable. If I make too many deviations from the original design in one go it would not be possible to know which had been a benefit & which had not. There are plenty of suggestions in this thread on how that might be achieved and I’m probably more aware of how the CG & wing incidence is so very critical.

Any further comments welcomed and thanks for your patience.

Ian

Edited By Ian Jones on 24/04/2011 01:04:22

[Tom Wright 2]

Hi Ian.

Congratulations on passing the B test.  .

TW2

PS I think the wing loading may be for the none EP version, best to weigh it ,inc batt.

 

Edited By tom wright 2 on 24/04/2011 01:04:52

Edited By tom wright 2 on 24/04/2011 01:09:25

[Ian Jones]

Posted by tom wright 2 on 24/04/2011 01:04:03:

Hi Ian.

Congratulations on passing the B test.

TW2

 

Hi Tom,

 

Thank you very much, been "meaning to do it for years", even did some training with Paul Heckles 4 years ago but just didn't get around to doing the test. Done it at last .

 

Ian

[Tom Wright 2]

Just done a quick re calc based on your wing area of 442 sq ins and an AUW of 3.5 lbs and the wing loading comes out at 18.6 oz per sq ft .

 

Tom.

[Ian Jones]

Hi Tom,

 

Sorry, I think it's me that's cross posted.

 

I'll re-check the weight before it flies again but even at 18.6ozs wing loading it doesn't seem excessive to me or is my inexperience with gliders showing?

 

Ian

[Tom Wright 2]

Hi Ian.

In my experience a high aspect ratio wing loaded at 18 oz goes pretty fassssst.

Tom.

[Ian Jones]

OOhh right then, I'll bear that in mind.

 

I'll get back to you when it's repaired and have another chat if you don't mind.

 

Ian

 

[Tom Wright 2]

OK will look forward to that.

Tom.

[Peter Currey]

Hi Everyone,
I had exactly the same happen to my Fly-Fly DG-1000, last year. The damage to the fuselage was so great that I had to get a new one! I have just finished the re-build and it's sitting on the bench waiting to be set up. What movements did you find best, on aileron, elevator and rudder? I can't find recommended throws anywhere! Also, would you expect to use Expo and if so, how much?
Thank you in advance for any help you can give.
Peter

[Ian Jones]

'eck, has it been 8 years .

After the help and investigations, which I appreciate and still expect to make good use of, I am now starting another new year thinking, "I'll get DG1000 flying this year".

You have my sympathy Peter, I've pretty much decided to forget the motor and launch off a slope. Before that I will be making very precise checks on the CG.

[Peter Currey]

Thanks Ian,
Unusually, for a thread on here, when there was no response within 12 hours, I wondered if I had done the wisest move attaching my query to an old thread?! So I reposted, tonight as a new thread and have had several responses so far. I shall give it another go, trying to choose the best advice then checking and double checking everything before attempting to commit aviation!
I shall bear your words of caution in mind.
Cheers,
PC

[Paul Marsh]

Taken a long time to get back into the air. Even an experianced flyer can get caught out and put the enthusiasm out o a model.

I've known Ian from Mid Cheshire club years ago - a very proficient flyer and a stickler for accuracy and detail and doesn't make an obvious mistake, and apart from me , one of the best flyers around. (He also was a judge at model events in the past)

Though high aspect-ratio wings really have a nasty stall tendency - they work very well and efficient - in a trade off for some aspects - such as a stall. Being a model, this is aggrivated more so, though even full sized pilots have come a cropper due to a sudden stall

[Ian Jones]

Thanks for those kind words Paul. If, when I get it flying I'll post an update here.