HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 17, 2014, 05:25 PM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Discussion
Super Scorpion build

Greetings all

I'm building a Ben Buckle version of the Scorpion (Super Scorpion) and am toying with how much down and side thrust to employ, and would appreciate feedback from builders of this kit as to what they have found necessary in practice.

I'm going to use a Saito 30 four stroke. The plan shows a positive incidence to the tail plane, although it's not specifically highlighted in the textual notes on the plan. The tail plane is quite large on this model, and has a lift generating section.

I'd normally use 2 degrees of both down and side thrust, but tips based on experience would be appreciated.

Thanks in advance,

Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 17, 2014, 08:46 PM
Registered User
Warren B's Avatar
Mt Evelyn, Melbourne, OZ
Joined Dec 2008
687 Posts
I used about 2 degrees down and side thrust.
Can confirm the positive incidence on the tail is needed.

Mine still flies with a fair bit of down elevator trim, and a bit more down trim mixed in with throttle as well.
This indicates a bit more than 2 degrees down thrust would be a good idea, but being lazy, I find the throttle mix quicker.
Only issue is a bit of ballooning if I chop the throttle too quickly.
Warren B is offline Find More Posts by Warren B
Reply With Quote
Old Sep 18, 2014, 08:39 AM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Thanks Warren,

Appreciate the response, which is very helpful.

It's quite a complicated build... And I have to admit some head scratching has been needed to progress the fuselage. I've added a picture of where I am so far.

Cheers
Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Last edited by Chris Jenkins; Sep 18, 2014 at 08:57 AM.
Reply With Quote
Old Sep 18, 2014, 09:18 PM
Registered User
Blenheim, NZ
Joined Dec 2007
1,213 Posts
Watching

I'll watch with interest Chris. Nice model.

Allan
AllanK1 is offline Find More Posts by AllanK1
Reply With Quote
Old Sep 19, 2014, 05:04 AM
KNS
Registered User
Switzerland, SO, Olten
Joined Dec 2012
399 Posts
subscribed
KNS is offline Find More Posts by KNS
RCG Plus Member
Latest blog entry: Latest concluded projects
Reply With Quote
Old Sep 19, 2014, 08:12 AM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
S\ Scorpion Build

Thanks guys,

I'll post pictures as the build progresses. As I'm on a deadline for shipment back to UK I've got three weeks to get the structure as complete as possible !

So far the main issue has been interpretation of the plan, and correction of some dimensional discrepancies. Due to lack of time I decided on a kit rather than a plan, but although the balsa cut parts look accurate, the ply formers just wouldn't work for me. .. So these had either to be corrected or replaced. But in spite of these niggles, it's a fun build but far more complicated than I envisaged. For example, due to the triangular section of the fuselage the cross brace joints to the longerons have to take account of both the taper to the tail, and the triangular offset. Similarly as the fuselage tapers to the tail the lower and middle longerons twist at different angles... Hard to explain, but I hope this makes sense.

Watch this space !

Regards,
Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Last edited by Chris Jenkins; Sep 19, 2014 at 08:20 AM.
Reply With Quote
Old Sep 19, 2014, 08:51 AM
I like real wooden aeroplanes!
Sundancer's Avatar
South-west France
Joined Sep 2007
5,191 Posts
Quote:
Originally Posted by Chris Jenkins View Post
.......but far more complicated than I envisaged. For example, due to the triangular section of the fuselage the cross brace joints to the longerons have to take account of both the taper to the tail, and the triangular offset. Similarly as the fuselage tapers to the tail the lower and middle longerons twist at different angles... Hard to explain, but I hope this makes sense.

Watch this space !

Regards,
Chris
Makes sense to me Chris, I have just finished wrestling with a similar (though less extreme) fuselage section on my Bill Winter "Airknocker" and it was a so-and-so!
Sundancer is offline Find More Posts by Sundancer
Reply With Quote
Old Sep 19, 2014, 01:59 PM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Quote:
Originally Posted by sundancer View Post
makes sense to me chris, i have just finished wrestling with a similar (though less extreme) fuselage section on my bill winter "airknocker" and it was a So-and-so!


Nice to know I'm not the only one !
Chris Jenkins is offline Find More Posts by Chris Jenkins
Reply With Quote
Old Sep 22, 2014, 07:21 AM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Progress

Some progress made with the Super Scorpion over the past couple of days, and here are a couple of (not very good) pictures .

The cabin has been a bit of a headache to get right, and especially so as the formers drawn on the plan are incorrect. Having sorted that out, I was a bit worried about the structural integrity of the whole cabin area, and especially the forward main former which is fitted at quite an acute angle and takes the full force of the rubber wing retaining bands. I therefore made the formers from 1/8th spruce with balsa insert pieces, and will probably fit two small carbon fibre braces later in the build.

This is a lightweight build, and as my models have to put up with quite a lot of rough and tumble I am prepared to sacrifice some extra weight in the interests of durability and long life. I've replaced the 3/16th balsa cabin window braces aft of the wing with spruce as an example of this. This whole area has been fitted with plenty of "green" to allow sanding to get the cabin glazing angles correct ( still to do).

So far things are progressing fine, and I hope the major hassle with the fuselage is over.... The wings should be easy after this (famous last words)

Anyway, the time spent in getting alignments correct paid off as the cabin top is at the correct angle, and all square with the tail feather seating.

I've built in 2 degrees of down, and 2 of right (thanks Warren). Took a look at the Keil Kraft 1946/47 plan for the Scorpion, and probably using this scaled up would have been a better option for this build !

Regards
Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Last edited by Chris Jenkins; Sep 23, 2014 at 07:37 AM.
Reply With Quote
Old Sep 23, 2014, 09:02 AM
Registered User
New Zealand, Canterbury, Christchurch
Joined Jun 2008
246 Posts
Hi Chris,

Watching with interest. I'm currently building the Outerzone version of the Super Scorpion.

That plan has all the usual issues with discrepancies in size and shape of components. I had to build up some of the tailplane ribs and shorten others. I chose to plot my own wing ribs (NACA 6411 is similar), which worked well (the ribs fit).

I've modded the wing spar to an I beam design, and changed the trailing edge to two pieces of 1/16 top and bottom, similar to the Junior 60 wing.

I normally draw my own fuselage formers to match the plan and side views anyway, because the ones shown never fit.

I was thinking of reinforcing the cabin area a bit as well but other than that I will build it as per.

I'm still toying with bolting the wing and tail plane on but may just stick with rubber bands.

I will be covering mine with silk over doculam.

I'm hoping a diesel converted OS .20 will be enough (apparently they fly OK on four stroke .26 and .30s) so my power may be similar?

Your build is looking very nice, I'll be happy if mine looks half as good.

Cheers,

Dave H
gerryndennis is offline Find More Posts by gerryndennis
Reply With Quote
Old Sep 23, 2014, 12:48 PM
Registered User
Paul_BB's Avatar
France, IdF, Lagny-sur-Marne
Joined Feb 2007
547 Posts
Nice piece of artwork, subscribed.
Paul_BB is online now Find More Posts by Paul_BB
Reply With Quote
Old Sep 23, 2014, 06:05 PM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Quote:
Originally Posted by Paul_BB View Post
Nice piece of artwork, subscribed.
Thank you Paul !
Chris Jenkins is offline Find More Posts by Chris Jenkins
Reply With Quote
Old Sep 23, 2014, 06:21 PM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Quote:
Originally Posted by gerryndennis View Post
Hi Chris,

Watching with interest. I'm currently building the Outerzone version of the Super Scorpion.

That plan has all the usual issues with discrepancies in size and shape of components. I had to build up some of the tailplane ribs and shorten others. I chose to plot my own wing ribs (NACA 6411 is similar), which worked well (the ribs fit).

I've modded the wing spar to an I beam design, and changed the trailing edge to two pieces of 1/16 top and bottom, similar to the Junior 60 wing.

I normally draw my own fuselage formers to match the plan and side views anyway, because the ones shown never fit.

I was thinking of reinforcing the cabin area a bit as well but other than that I will build it as per.

I'm still toying with bolting the wing and tail plane on but may just stick with rubber bands.

I will be covering mine with silk over doculam.

I'm hoping a diesel converted OS .20 will be enough (apparently they fly OK on four stroke .26 and .30s) so my power may be similar?

Your build is looking very nice, I'll be happy if mine looks half as good.

Cheers,

Dave H
Think you were wise Dave, but I suppose in my nievety I believed that most of the issues would have been sorted out with a redrawn plan, and commercial kit.
As it is it's taken ages sorting things out.... but undaunted I'll set to today to add the wing retaining gussets and bands dowels plus sorting out the front end with forward battery compartment. Even the supplied nose block doesn't fit !

I'm sticking with the banded wing, and plug and bolted tail plane, closed loop rudder control and pushrods (via transfer linkage) for elevator. I'll add some 1/4 sheeting infill to the cabin top to take my preferred wing seating method which is cut pieces of food tray anti slip matting that. I've used on my recently completed KK Falcon (as suggested by a very smart forum member!).

One thing I have noted with the Outerzone plan is that the tail plane + incidence is missing... The BB plan has it, and according to Warren it's required to avoid ballooning in RC mode.

Please post pictures Dave... Would love to compare your solutions, and good luck with the build.

Regards
Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Last edited by Chris Jenkins; Sep 24, 2014 at 08:25 AM.
Reply With Quote
Old Sep 23, 2014, 06:30 PM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
To glaze or not to glaze ?

I'm toying with foregoing the aft cabin glazing (aft of the trailing edge) in favour of covering... This is not entirely laziness .. ..but I tend to think the result visually balances the very long cabin pleasingly on examples I've seen on the internet.

Any comments/views ?
Chris Jenkins is offline Find More Posts by Chris Jenkins
Reply With Quote
Old Sep 24, 2014, 08:07 AM
Registered User
Chris Jenkins's Avatar
United Kingdom, Wales
Joined Feb 2005
917 Posts
Well I didn't do as much as I had planned, but still the wing retaining dowels are in place now after fitting gussets to facilitate covering (these need to be sanded to the correct profile).

Some further gussets added to the cabin area, and the tail plane plug and rudder control wire outlets fitted.... and oh, the forward cabin roof part fitted.

Regards
Chris
Chris Jenkins is offline Find More Posts by Chris Jenkins
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product Freewing Super Scorpion 80mm EDF Jet T-CAT Foamy EDFs 324 Jan 26, 2015 10:34 PM
Sold AD Super Scorpion Hinckley Bill Aircraft - Fuel - Jets (FS/W) 1 Feb 26, 2014 09:36 AM
Super scorpion drumy Vintage & Old-Timer Designs 12 Dec 21, 2004 04:52 PM
Mrs. H and Ben Buckle Super Scorpion pics! tim hooper Electric Plane Talk 25 Dec 23, 2003 06:22 AM