Another Parnall Elf

A

adzam

Guest
:no1b: yup a truly excellent thread greyhead,very very informative and with the pictures us non aero modellors can see how these things are put togethor and the thought process and occasional "redesign" all fits togethor.

:groupwave excellent mate
 
P

Phoenix

Guest
well you gotta realise though if you had a model you really like to drive or fly you would use it as often as you can wouldnt you?
 
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
This is it, the weathers OK and the time is right, so pack up the car and head for the field. When I arrived the steady breeze had dropped to an almost flat calm, still this is better than going the other way.


First things first, a few photos just in case the worst happens, here’s one on the starting box and table.


EPSN0007 (2014_02_15 10_29_30 UTC).JPG


With the engine nicely warmed up a couple of runs to check the ground handling; no problems, straight as a die, but then it would be, the gyro’s doing all the work not me! Gradually build up the speed to see if the rear folding sections of the lower wings stay in place over the bumps and she’s nearly airborne, close the throttle and everything’s fine so the next one is for real.


This time a bit more throttle to ensure we reach flying speed and away she goes, as soon as the wheels leave the ground the left wing drops and it needs full right aileron just to keep level. Too late now to abort so gain height and see what we can do. A few clicks of right rudder eases the problem but when the throttle is closed a sudden right turn, it’s obvious that landing is going to be quite a challenge so I decided to cruise around at a safe height to let the nerves settle. Gradually reducing throttle and adjusting rudder trim line up for a landing, got to get this right as any sudden throttle change will result in an equally sudden turn! More by luck then judgement I hit the square and she’s down in one piece.


Time for the post mortem. First the ailerons are virtually useless so must use CAR (coupled aileron rudder). The trim changes with throttle indicate the need for more engine right thrust. I had intended to build it at 0º, as I have done with all my previous models, but the club aerobatic expert Bob Wasson gave the model the “once over” and declared that there was about ½º left thrust (note this is an expert not an “expert”!!) and he suggested I adjust the thrust line to 2º right thrust. At home careful measurements proved he was correct about the left thrust and I duly modified the bearers; could only get about 1½º right because of lack of room under the cowl.


In the background of this photo Bob is preparing his aerobatic model.


EPSN0003 (2014_02_15 10_29_30 UTC).JPG


I mixed CAR and tried again a couple of weeks later, what a difference, the model was now completely controllable but still turned left as the throttle was opened, if I’d managed to get the full 2º as suggested I’m sure it would have “flown on rails”. I now also mix in a small amount of right rudder with throttle and she flies like a “good un”. A wonderful sight on a low, slow pass with the Laser burbling away at ¼ throttle, it doesn’t get much better than this!
 
Last edited by a moderator:
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
OK that’s the thread finished, unless that is anyone wants a photo and / or a more detailed explanation of anything. I’d like to thank everyone who posted replies, their efforts certainly encouraged me continue.

I’ll have to find something else to occupy my time now but then I’m sure “senior management” will find a job or two, there’s the tiling in the kitchen to finish and what about those shelves I promised to make last year! Then again I’ve always fancied an Acro Wot to fling about when the weathers not suitable for scale flying. Decisions, Decisions!
 
A

adzam

Guest
many thanx once more greyhead

as much as we all have enjoyed your thread, a tutorial on shelfs or tiling draws the line mate ;)

look forward to more.

Adz..
 

wonwinglo

SMF Supporter
Joined
Apr 18, 2004
Messages
6,754
Points
113
First Name
Barry
Thanks for all that appraisal Grahame of your Elf,sounds like very similar experience to my first flights as well with my own Elf,from the looks of her you would not think that she could be such an handful initially would you ?

Get the cupboards done and then get cracking on something interesting,ever thought of a twin ? they are quite a challenge and sound great in the air.
 
B

Bluewavestudios

Guest
Once Again...Excellent Thread Grahame....A pleasure to read and a lot of useful advice taken on board from your pics too (It's always nice to see how someone else does things) and I am glad that you reached a successful conclusion with successful flights.....OK there may not be much flying weather left for this year...give or take the odd day or so, but I am sure you are going to be having a lot of fun with this one next year.

Regards...........Mark. :welldone:
 
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
We recently put on a model display at a local airfield as a “thank you” for them doing a vintage fly past at our annual model air show and a full size enthusiast liked the Elf so did some research. Apparently of the 3 full size built, 2 crashed killing the pilots, so maybe the handling difficulties we experienced were not too far out!

No flying shots available at present, I’ve not yet had the courage to put the Tx down and pick up the camera. Next season I’ll get it organised.

Grahame
 

wonwinglo

SMF Supporter
Joined
Apr 18, 2004
Messages
6,754
Points
113
First Name
Barry
We recently put on a model display at a local airfield as a “thank you” for them doing a vintage fly past at our annual model air show and a full size enthusiast liked the Elf so did some research. Apparently of the 3 full size built, 2 crashed killing the pilots, so maybe the handling difficulties we experienced were not too far out!No flying shots available at present, I’ve not yet had the courage to put the Tx down and pick up the camera. Next season I’ll get it organised.

Grahame
*** Grahame the full size machine is awful to fly,same problem lots of adverse yaw,one of the Shuttleworth pilots told me this,could be also why they wanted to sell her off a couple of years ago also ?

One example used to fly from the Duke of Richmonds airstrip at Badminton pre-war.

I think challenging is the word ! very draggy due to all of those struts,mine needs to be flown onto the ground rather than a glide approach.
 
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
I must admit that none of my biplanes have had a very good glide angle, just so much drag from wires and struts etc.! The SE5a would fly very slowly; almost hover with a bit of head wind, but still needed power to land.





The Albatros was the worst, that massive fuselage, even though it was very streamlined for its time, has so much drag. Even at only 54" span the Laser 70 certainly didn’t overpower it.





Landing with a fair amount of throttle needs quite a lot of practice but when it goes right it makes for a very scale like touch down and that’s what scale modelling is all about isn’t it?
 
Last edited by a moderator:
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
I was recently asked what prompted me to take construction photos during this build, well it wasn’t for self-gratification or indeed with the intention of producing this thread!

When I became “interested “ in the Elf I suggested to the better half that we were long overdue a visit to our friends and relatives in Leicester; by chance this happens to be fair proportion of the way down to the Shuttleworth Collection (crafty or what?). Whilst the wife and sister-in-law hit the shops my brother and myself headed for Old Warden armed with a newly acquired digital camera. We discussed the pros and cons of the Elf and decided to build “parallel projects”, his was to be 10% larger to accommodate a Laser 80. I started with the fuselage and Dave with the wings, the idea being to “share” the problem solving which is always required on a project of this nature by e-mailing photos of any problems / solutions as we went along. Unfortunately due to a medical problem Dave only got a far as one wing panel but, luckily as it turned out, I continued with the running commentary.

Would I do it again? You bet I would!!

I’m one of those modellers who enjoy building and flying in equal measure, it must be very frustrating for the ARTF brigade waiting on the English weather; producing this thread has allowed me to “re-live” the build and hopefully pass on some useful ideas at the same time.
 

wonwinglo

SMF Supporter
Joined
Apr 18, 2004
Messages
6,754
Points
113
First Name
Barry
And very successful it has been too Grahame,like yourself the building is very much part and parcel of the hobby and I never treat this as a chore,nothing nicer than seeing a model slowly evolve,more power to your modelling elbow for 2005 ! perhaps we will see another biplane project evolve ?
 
Joined
Oct 14, 2004
Messages
90
Points
8
First Name
David
Have you decided on a new project yet Grahame? Following a link in this month's Aeroplane http://www.vought.com/heritage/html/down.html there are some 3-views of Vought aircraft and the VE-7 took my eye as a 'different' subject with the advantage that it should be possible to mount the engine upright as with the SE5. Showing my ignorance this is a new plane to me but one with pleasing lines, I may give it a go when my PIK 20 renovation is complete.
 
Last edited by a moderator:
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
Techydave

I agree it looks as if it’s got nice proportions for a RC model. I was interested to see the photo of the floatplane; our flying site at Redmarshall is in a dip and is prone to flooding so that conversion might come in handy!!

Grahame
 
D

duncan

Guest
A very useful site. Pity other manufacturers didnt have something similar for modellers. See Dave Platt`s "Kingfisher" magnum opus in this month`s RCMW (Jan 05).
 
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
It has been pointed out to me that the method of building the wings is not very clear. This from my brother who has seen the finished article so I’m surprised nobody else has commented! Having gone through the thought processes to devise the method it seems fairly straightforward to me but hopefully this will clarify things a bit.


TYPICAL WING SECTION


wing section.png


Remove shaded section from ribs and make additional sections for “riblets”. Stack together and drill 1mm hole in approx. the marked position.


Make the balsa web by gluing together strips cut from sheet balsa (approx. 2” x the width of the sheet).


The assembly sequence is:


1. Thread ribs onto rear spar, pin into position over plan and glue.


2. Glue 1/8" x1/4” spruce spar in position.


3. Glue 1/16” balsa web in position, NB grain direction from LE to spar.


4. Glue 1/4" x1/4” spruce spar in position.


5. Thread removed rib sections and any “riblets” onto a length of button thread to form a “necklace”.


6. Glue rib sections and “riblets” in position.


7. Glue upper and lower LE sections in position.


8. When dry fix one end of thread to a solid point, tension the thread and fix the other end.


9. Soak the thread with thin Cyano.
 
Last edited by a moderator:
Joined
Oct 13, 2004
Messages
611
Points
16
First Name
Grahame
I got talking to another modeller recently about the pros and cons of adjustable tail incidence, basically is it worth the trouble? Here are my thoughts on the matter and a couple of photos to prove the point.


If the mechanism is “out in the open”, as is the case with the Elf, then I’d say as it needs to be modelled for scale authenticity the small amount of extra work involved in making it operational is well worth it. If it is hidden and you’re not worried about perhaps having a fair amount of elevator trim on show why bother?


The full size is adjustable in flight but I thought that was a step too far!





The tail is mounted on brackets made from thin steel and attached via ball joints to allow for the fact that the brackets are fitted to the tapering fuselage sides.


The adjuster consists of a 2mm rod threaded at both ends with a nut soldered at one end. The rear of the fuselage has a dowel, with a length of snake inner down the centre, into which the adjuster is screwed in or out to alter the tail incidence. A lock nut goes the other side of the rear tail brace to keep things solid.


The braces are attached to the tail and fuselage by steel brackets again using closed loop adaptors and 14BA nuts and bolts. There is very little movement at the fixing points as the tail incidence is altered and the bolts don’t need to be slackened.


TAIL_2 (2014_02_15 10_29_30 UTC).JPG


In this shot you get a good view of the tailskid, moulded using epoxy and carbon fibre and the elevator operating arm. The closed loop for the rudder goes in the space between the fuselage and the tail plane. EDIT can't find the photo but this shows the brace from tail to fin which is virtually the same.
 
Last edited by a moderator:

wonwinglo

SMF Supporter
Joined
Apr 18, 2004
Messages
6,754
Points
113
First Name
Barry
Grahame,now this idea I really like and approve of,it has always been my contention that more models fly badly due to incorrect tail incidence,the problem is as we all know that fixing the tailplane is very much an hit and miss affair,a few thou can make such a very big difference to the trim of the model in flight and more often than not we continue to fly our models out of longitudinal aerodynamic balance,by incorporating such a feature as you have here the aircraft can be made to perform to its peak in terms of aerodynamic efficency.Incidently the late Howard Boys once wrote that it was very doubtful if any model had its tailplane set correctly on its very first flight ! so who are we to argue this very valid point froma true pioneer of scale model aircraft.

Incidently in flight tailplane trim would not be impossible to achieve just as the full sized counterpart.
 
Last edited by a moderator:
Top