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Peter Miller Druine Turbulent, CG and Throws


Devcon1
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Hi All
 
I gained a superbly built and finished Turbulent built from Pete's plan from that famous auction site, It is yellow with a an OS40 FS and a lovely dummy opposing cylinder head.
 
Peter might remember it from said site as he posted a little reply to the then sender at the time it was up for auction earlier on this year.
 
Today was test fly day and boy did I have a fright, It was very exciting and I was lucky to get it down, it was a bit hairy an I believe the main reason it did not drop a wing badly were those wonderful leading edge slats.
 
But in truth the cause was me, I also gained the original mag with the plan feature and scaled up the CG position from a picture of the plan, but, I guessed the control throws and got them wildy wrong, far far far too much movement on that massive elevator, I estimate I flew the whole scary circuit on not much more4 or 5mm of stick movement when I realised what was wrong, what a plonker...
 
Question, can anybody from experience tell me the true CG and control throws they use for this georgeous plane.
 
Anybody got a Precedent kit lying around in the loft as I'd love it to have a bigger brother to play with.
 
Many thanks
 
John
 
 
 
 
 
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CG should be at 25% from the leading edge for safety.
 
You are in luck. The plan was published in the USA first and the throws are shown on the plan in that magazine.
 
Elevator 3/4" each way. Ailerons 7/8" each way. Rudder 1 3/4" each way.
 
The CG as shown on the plan is further back than I would use these days. Bring it forward to a quarter of the wing chord for safety.
 
By the way , I have been commissioned to design a new Turbulent for a part kit manufaturer. It will probaly be about the same size or may be a bit bigger.
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Hi Peter,
 
Many thanks for that, I'll have a further session tonight on the radio and with the ruler.
 
 
In my eyes the Druine Turbulent is the most perfectly proportioned and "right looking" scale model ever, I've hankered after a Turby for years now and got this beauty, I'd love to know it's history and who built it. So if anybody built one with the following features I'd love to talk to them.
 
Finished in yellow Solartex, emery cloth wing steps, pitot tubes, battery compartment under the fuel tank, filler nozzle in front of cockpit, fantastic detailed hand made instrument panel and two sets of wheels one with matching scale yellow hub covers.
 
Please convince the kit manufacturer to make a bigger one, I'm sure if the Precedent kit or a ARTF was on the market it would be a success. If it was bigger than your original I would be in the queue.
 
I've since had another flight having tamed the elevator and it's looking good.
 
Peter, do you think I should keep adding nose weight bit by bit until no down elevator trim is required in normal mid throttle level flight.
 
Many Thanks
 
Johnj
 
 
 
 
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I would be tempted to move the CG forward to the 25% chord position and then move it back a bit at a time. That is the normal proceedure.
 
I have lost a couple of my better scale model because I had the CG too far back.
 
I wanted to do a 1/4I must do soem more measuring s cale version but I don't think I can get it in the car.
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I would be tempted to move the CG forward to the 25% chord position and then move it back a bit at a time. That is the normal proceedure.
 
I have lost a couple of my better scale model because I had the CG too far back.
 
I wanted to do a 1/4I must do soem more measuring s cale version but I don't think I can get it in the car.
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Hi Peter,
 
I'll follow that advice and keep you posted.
 
Given the potential light mass of the model could you design it with plug on wings to keep the "transportability" factor.
 
Regards
 
 
John
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There are several reasons why I will not be designing plug in wings,
 
1) I like to keep my models as simple as possible and plug in wings do add quite a lot of complication to the designing and building.
 
2) Sometimes it is easier to use plug in wings, models such as the Wittman Tailwind and my new Legrand Simon. But these aircraft have wing struts to make the wings rigid.
 
3) The dihedral angle would make things quite hard to do with carbon fibre tube etc and wire could flex without the struts.
 
4) At 57" span transport should not be a big problem. I drive a French Aixam microcar. I can get a long wing in beside the passenger seat but I can't get a fuselage longer than 48" in the back. This decides how big a model I build.
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You commented that you needed a ot of down trim.
 
In researching my new model I have made an interesting discovery. The 3-views all show that tailplane lined up with the datum line.
 
Careful analyses of phtos show that in fact the tailplane is set at a slight positive incidence. Not as much as the wing. In effect this gives a little down thrust.
 
At least that explains the need for so much down trim.
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Hi Peter,
 
I see what you mean about plug in wings, that's why you're a designer and I'm just a flyer.....
 
I will let you know how I get on with the down trim.
 
(I've just retreived your RV3 plan for a winter build)
 
Regards
 
John
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  • 1 month later...
Hi Peter
 
It wan't you that purchased that untouched Precedent Turbulent kit from Ebay by any chance was it.?
 
Regards
 
John
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No. I don't build models that size and these days I don't normally build from kits anyway.
 
Had I known about that one I am sure that one of our club members would have snapped it up. He has been on about one for ages. Well, ever since I started designing my new one.
 
The new one is 57" span, OS FS 40 Surpass, weight 5 lbs 8 oz. wing loading 21 oz. per sq. ft. It flies like a dream.
 

And before anyone asks. it is going to be a part kit More details when things have been finalised so please don't ask yet.


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  • 4 months later...
  • 2 weeks later...

Hi,

Sorry to go off the thread a little but I'm hoping somebody might be able to help.

I have also just aquired an orignal later Precedent Turbulent kit but I'm missing the instructions. I'd be happy to pay for P&P and buy a beer for anybody who could photocopy a set for me.

Many Thanks

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  • 4 years later...
  • 4 years later...

Daniel, probably best to just PM Peter and ask him if the plan for the 57in span Turbulent is available anywhere? I may be wrong but I think this model was commissioned by RAM Models with the intention of producing a kit, so presumably they own the copyright now? I did google 'RAM Models' but the first hit was an entirely different type of model!

 

The 58in span Turbulent that Peter designed many years ago is a sweet flying aeroplane by all accounts but the construction very much follows the full size design, so is not a quick build sadly. I used to own a set of full sized Turbulent plans before I 'saw the light' and bought an airworthy example (G-AWMR), not wishing to spend the next six years of my life building one! To me, some of the charm of this aero-modelling hobby is being able to quickly knock together a simple rendition of a full sized aircraft whilst not getting hung up about scale fidelity. I love Danny Fenton's dedication to the scale holy grail but it is not for me! 

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