SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jan 24, 2013, 10:43 AM
Failure is not an option
casor's Avatar
Boyertown, Pa
Joined Mar 2007
818 Posts
Quote:
Originally Posted by heli_madken View Post
I designed a shelf for weight up at the front of the nose so its easy to get lead in there, it took 1.08Kg (2lb 6oz) to achieve the 90mm CG

So with the estimated finished weight now at 9.5kg wing loading has increaseed to 35.4 oz/sq.ft with pretty much the same stall speed as before 29.5mph

Any opinions?
Ken - in my opinion a WL of 35 on a model of that size will be no problem. Wing volume is the key and as long as you have washout it should be a stable floater. I would run the cube numbers again but they probably won't change much, thus proving my point. I also agree with the comments about flying it more nose heavy than it should be according to the calculations and 25% MAC on a semi symmetrical wing seems about right. If it is sluggish on the controls and wants to come down right away when you cut the power, you can move it back from there.
Rob
casor is offline Find More Posts by casor
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 24, 2013, 11:06 AM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
3,466 Posts
You know, given a wing loading that high it might be as well to remove the gun for the first flight or two until you see how well it flies and have a better idea how much extra weight the wings can carry.

I'm sure the test flights of the full size would have been made without armament installed!

If you have plenty in hand then you can add the gun back without undue concern. Would that be possible?
eye4wings is offline Find More Posts by eye4wings
Reply With Quote
Old Jan 24, 2013, 11:09 AM
Registered User
United States, WI, Fond du Lac
Joined Sep 2008
1,733 Posts
The wing loading isn't terrible for a plane of that size. If its performance is lacking after its properly trimmed you can think about rebuilding the tail section using the lightest possible methods. A saving of an ounce or two would save probably 5 or 6 times that much lead in the nose.
pmullen503 is online now Find More Posts by pmullen503
Reply With Quote
Old Jan 24, 2013, 01:07 PM
Failure is not an option
casor's Avatar
Boyertown, Pa
Joined Mar 2007
818 Posts
Removing the gun

Is a good idea, the question being how much does it contribute to nose weight. Would also take some of fear out of landing.....
casor is offline Find More Posts by casor
Reply With Quote
Old Jan 25, 2013, 01:47 AM
Registered User
Liverpool, England
Joined Jan 2005
1,143 Posts
Hi Removing the gun is possible but it is contributing to nose weight as the cannon itself is alloy and sticking way out front, I was toying with the idea of replacing the muzzle with a steel tube as it would be the most effective way of adding nose weight
heli_madken is offline Find More Posts by heli_madken
Reply With Quote
Old Jan 25, 2013, 04:39 AM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,551 Posts
I wouldn't worry about the WL Ken. My 119 is 109" ws and has a WL of 46 oz/ft., weighs 30 lbs, and flies like a 10 lb trainer. But CG, that's another matter. If you have to add lead to achieve, DO IT!

J
J Morgan is offline Find More Posts by J Morgan
RCG Plus Member
Latest blog entry: OV-10A Bronco from Palmer Plans
Reply With Quote
Old Jan 25, 2013, 06:39 AM
Registered User
Liverpool, England
Joined Jan 2005
1,143 Posts
Thanks Pat, makes me feel much better, Ken
heli_madken is offline Find More Posts by heli_madken
Reply With Quote
Old Feb 03, 2013, 12:10 PM
Registered User
Liverpool, England
Joined Jan 2005
1,143 Posts
Been slammed with work and preparation for a full Ofsted inspection so not much chance to get out to the garage.

Wings are now complete, several coats of primer and rubbed down ready for the next stage

Up next is the engine cowl plug
heli_madken is offline Find More Posts by heli_madken
Reply With Quote
Old Feb 03, 2013, 01:10 PM
Flying electric since 1986
Mark Wolf's Avatar
USA, IN, Brownsburg
Joined Oct 2000
1,764 Posts
I just can't get over the workmanship on this. It looks like you pulled it out of a mold instead of gluing together some dead trees. Well done.
Mark Wolf is offline Find More Posts by Mark Wolf
RCG Plus Member
Latest blog entry: Stevens Aeromodel Skybuggy 100
Reply With Quote
Old Feb 03, 2013, 01:54 PM
Registered User
Doug Bartley's Avatar
Canada, ON, Owen Sound
Joined Oct 2008
2,809 Posts
Hi Ken Have to agree with Mark here, outstanding!!
If it looks like you'll need nose weight (ie: lead), a perfect place to help would be thicker cowls than normal. A few ozs out there would go a long way in helping the balance. Just a thought Doug B
Doug Bartley is offline Find More Posts by Doug Bartley
Reply With Quote
Old Feb 03, 2013, 02:17 PM
"RC ADDICT" in Toronto!
wollins's Avatar
Toronto Canada
Joined Aug 2004
1,730 Posts
Hey Ken ... beautiful is an understatement! Quick question ... did you machine your tailwheel ... if not where did you source it from?

Colin
wollins is offline Find More Posts by wollins
Reply With Quote
Old Feb 04, 2013, 06:22 AM
Registered User
Liverpool, England
Joined Jan 2005
1,143 Posts
Thanks Everyone, Colin the tailwheel was from Hobby King, I think it was simply listed as a lightweight aluminium hub wheel
heli_madken is offline Find More Posts by heli_madken
Reply With Quote
Old Feb 04, 2013, 08:13 AM
Registered User
Ducky22's Avatar
Canada, ON, Mississauga
Joined Apr 2011
391 Posts
Looking fabulous Ken, I bet those wings seemed like child's play compared to doing the 61 with the spoilerons?
Ducky22 is offline Find More Posts by Ducky22
Reply With Quote
Old Feb 04, 2013, 04:02 PM
"RC ADDICT" in Toronto!
wollins's Avatar
Toronto Canada
Joined Aug 2004
1,730 Posts
Quote:
Originally Posted by heli_madken View Post
Colin the tailwheel was from Hobby King, I think it was simply listed as a lightweight aluminium hub wheel
Sorry for not being clear Ken, I meant the tailwheel assembly, as opposed to the tailwheel itself. Looks like it's a trailing link/oleo set up ... I was looking for something similar hence my question

Colin.
wollins is offline Find More Posts by wollins
Last edited by wollins; Feb 04, 2013 at 05:12 PM.
Reply With Quote
Old Feb 05, 2013, 01:25 AM
Registered User
Liverpool, England
Joined Jan 2005
1,143 Posts
Sorry Colin, I machined the yoke myself, its spring loaded so no need for an oleo, its just a hollowed out piece of alloy bar

Cheers yes it was a breeze to make the wings and they are so light compared to the Widow
heli_madken is offline Find More Posts by heli_madken
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Wanted Electric OB on K&B 3.5/7.5 base Ducati-Rider Boats (FS/W) 1 Jun 26, 2012 09:54 AM
For Sale New #8836 K&B 3.5cc piston/liner/DF/O/B/I/B dankar04 Aircraft - Fuel - Engines and Accessories (FS/W) 1 Apr 26, 2012 04:36 PM
Discussion Thoughts on this design (Henschel P75) cadcyg CAD/CAM 2 Apr 18, 2012 11:28 PM
Build Log Henschel HS129 - Ground Attack Plane - Scratchbuilt Harpye Foamies (Scratchbuilt) 13 Dec 02, 2007 07:20 AM
Discussion Henschel Hs 129B-3 (1/12th Scale, Twin S400 DD) jfrabat Scale Kit/Scratch Built 17 Feb 27, 2006 01:55 PM