Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
August 23, 2019, 10:50:42 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 2 3 4 5 6 7 8 [9]   Go Down
Print
Author Topic: PZL Wilga for .5cc diesel  (Read 7639 times)
0 Members and 1 Guest are viewing this topic.
Squirrelnet
Gold Member
*****

Kudos: 31
Offline Offline

United Kingdom United Kingdom

Posts: 523


Topic starter


Ignore
« Reply #200 on: May 24, 2019, 02:51:18 PM »

Quote
an absolute plumber's toolbag

  Cheesy That phrase is going stay with me for sometime !!!  Cheesy

Logged
TimWescott
Gold Member
*****

Kudos: 14
Offline Offline

United States United States

Posts: 973



Ignore
« Reply #201 on: May 24, 2019, 03:41:13 PM »

...I've added a gnat's more downthrust too in anticipation of an increased  angle of climb under power...

I would expect that after trimming for the further-back CG the thing will have less of a tendency  to go pitch-up under power -- here's my wish that if you're surprised, it's not a BAD surprise!
Logged
Squirrelnet
Gold Member
*****

Kudos: 31
Offline Offline

United Kingdom United Kingdom

Posts: 523


Topic starter


Ignore
« Reply #202 on: May 24, 2019, 05:00:50 PM »

Thanks Tim, I'll keep you posted
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,056



Ignore
« Reply #203 on: May 24, 2019, 07:38:14 PM »

Good luck with it Chris. Here's to good weather, sunshine and little to no wind! Asking a bit I imagine Smiley Good luck to all you fellows flying in the Nats.

John
Logged
DHnut
Gold Member
*****

Kudos: 14
Offline Offline

New Zealand New Zealand

Posts: 613



Ignore
« Reply #204 on: May 26, 2019, 12:35:34 AM »

 Chris,
        Well done the Wilga looks very realistic with a good sit in the air. Just a thought, but the real aircraft will usually have a steep approach as all the slots and flaps are deployed with a lot of power on so you are not out of scale in flight terms. Even when clean I doubt if the real one has any sort of glide, probably like the average WW1 aircraft of about 1 in 3. 
Ricky
Logged
Squirrelnet
Gold Member
*****

Kudos: 31
Offline Offline

United Kingdom United Kingdom

Posts: 523


Topic starter


Ignore
« Reply #205 on: May 26, 2019, 12:59:35 PM »

Thanks Ricky.

Despite its rather too STOL final approach I'm very happy with the Wilga, it looks great under power and well worth continuing with the slats and flaps. In the Flying Only Comp at the Nats I came a very happy 4th, which considering its death wish glide at Old Warden, I can only thanks you guys for the help particularly with the CG position.

It's currently 45% and think I will try a tad further back still, stability was very positive under power in the blustery conditions and I'm also thinking of more downthrust as my power speed my still be less than the gliding speed, which will always end in a bad transition.

My epoxy glassed undercarriage fairing failed again so before I attempt something more radical I'll try the same design with a 1/32" ply reinforcer and layer of epoxy glass over the top
Attached files Thumbnail(s):
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Logged
ZK-AUD
Platinum Member
******

Kudos: 47
Offline Offline

New Zealand New Zealand

Posts: 1,113



Ignore
« Reply #206 on: May 26, 2019, 04:05:49 PM »

Chris I've been lurking and quietly liking this build as it has progressed.    Those steep arrivals are a challenge but I was looking at this problem and wondered whether you could try going the other way and make the leg extremely rigid.  (liteply leg covers epoxied on and silk bound with a piece of carbon rod running through the middle parallel to the existing wire) Then articulate and spring / damp the trailing arm section as per the real one  - a clothespeg style spring would do it.

Here's a rough-as-guts sketch of how I would approach it.  Ideally the articulated section would be silver soldered to the brass tube but you'd get away with soft solder with a good fillet.  The step in the brass tube is your forward stop against the spring tension
Attached files Thumbnail(s):
Re: PZL Wilga for .5cc diesel
Logged
Yak 52
Titanium Member
*******

Kudos: 64
Offline Offline

United Kingdom United Kingdom

Posts: 2,460


Free Flight Vagrant



Ignore
« Reply #207 on: May 26, 2019, 04:54:04 PM »

Very glad to hear it flew well Chris!  Smiley

At 45% you have a static margin of 16%, still fairly forwards in general terms. 5-15% is normal, depending on the model, with FF scale models tending towards the high side. Considering the generous tail volume (what you have is more like a duration model) you could afford to go a bit further back still.

Jon
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,056



Ignore
« Reply #208 on: May 26, 2019, 06:55:48 PM »

That's good news. I'm glad it performed well and as Jon mentions you still should be able to come back a little further. Mike's suggestion of an articulated, sprung trailing section to the UC leg is possibly a solution to your UC problems.

John
Logged
DHnut
Gold Member
*****

Kudos: 14
Offline Offline

New Zealand New Zealand

Posts: 613



Ignore
« Reply #209 on: May 26, 2019, 07:35:00 PM »

Chris,
        Your use of the 1/32" ply reinforcement should work. I am building (slowly) a Broussard and have used a similar approach with two facing pieces of 1/32" ply and a core of 1/8" epoxied around the leg and a torsion bar in the fuselage. The reinforcement should allow the trailing section to give a bit as the leg will be significently stiffened. The video was great and the glide reminded me of watching an RAAF Caribou on approach at Amberly where the nose seemed to point at the ground. Great spectacle. The way it coped with what appeared to increasing wind was impressive, clearly the slats were working.
Ricky     
Logged
Squirrelnet
Gold Member
*****

Kudos: 31
Offline Offline

United Kingdom United Kingdom

Posts: 523


Topic starter


Ignore
« Reply #210 on: May 28, 2019, 04:03:50 PM »

Nice design Mike thanks.

My first step is a 1/32" ply reinforcer in addition to the balsa fairing wrapped in epoxy glass from last time. Its very similar to Ricky's thoughts.  There is a little movement allowed in the wheel and axle thanks to the triangular section cutout in the centre of the fairing.( see pic in post 205) . The right hand leg has survived fine but in inside leg with a left hand 'glide' did not.

 If this one fails I'll try your idea Mike, as I'd already repaired it   Wink

Jon - That's good to know next step is a bit more tailweight
Logged
TimWescott
Gold Member
*****

Kudos: 14
Offline Offline

United States United States

Posts: 973



Ignore
« Reply #211 on: May 28, 2019, 04:18:33 PM »

I think you may find that more spring is required than the original had.  If I could figure it out, I'd recommend something that lets the LG collapse completely, then spring back.

But then, I fly control line because I'm not smart enough for free flight, so...
Logged
Squirrelnet
Gold Member
*****

Kudos: 31
Offline Offline

United Kingdom United Kingdom

Posts: 523


Topic starter


Ignore
« Reply #212 on: July 21, 2019, 12:59:50 PM »

I think you're right Tim it needs more springing. If I was going to build another...I'm not.. I would use a torsion bar on the main former which I would beef up to 1/8' liteply to cope. I would forget the thinner gauge front supports on the plan, they are not even scale anyway.

I have had to make some changes to the Wilga though.

I tried some more trimming at the Eddie Riding event a few weeks back but I couldn't get enough power out of the .5cc Redfin to haul the model into a decent climb. I tried again at Old Warden last weekend but despite fresh fuel there's not enough power to produce a decent climb out.

I think after the initial burst of power from the freshly run in 030 Redfin, the edge has just gone off the engine and I can't quite squeeze enough out it. The cure is hopefully an easy one - I bought the 049 version from Alex Phin at Old Warden. This really is a big brother to the 030 and the hope is, it will be able to warble away quite nicely to carry the Wilga aloft.

The downside is it's a bit heavier ! what was the wing loading again... oh well let's not worry about that  Undecided

I fitted the original engine using metal plates attached to much wider spaced bearers than would be usual. This means a couple of hours work making new plates for the new engine and the 049 is installed.

The engine is a tighter fit in the engine bay but no major surgery was required and even the cowling still fits, though it will need hole in it now to clear the compression screw. I have substituted a hardened steel allen bolt as it gives a cleaner more scale like look than the supplied comp screw.

Pic 1 The Redfin TBR 049 compared to the Redfin TBR MK II 030

pic 2  Engine fitted with 3mm Aluminium plates

Pic 3 and Pic ... it fits !!!

The only 'downside' so far is now have a spare Redfin 030 TBR... Hmmm a reduced size John Watters Albatros CIII perhaps ??....
Attached files Thumbnail(s):
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Re: PZL Wilga for .5cc diesel
Logged
DHnut
Gold Member
*****

Kudos: 14
Offline Offline

New Zealand New Zealand

Posts: 613



Ignore
« Reply #213 on: July 21, 2019, 04:05:19 PM »

The joy of using engine mounting plates. I am sure the extra power will be sufficient and a steeper climb will not be out of place as it is a STOL aeroplane. How much is the weight gain? Surely not too much. Lok forward to seeing it in August.
Ricky 
Logged
OZPAF
Palladium Member
********

Kudos: 180
Offline Offline

Australia Australia

Posts: 5,056



Ignore
« Reply #214 on: July 21, 2019, 06:37:30 PM »

Good luck with the trimming Chris. Hopefully that should do the job.

John
Logged
3view
Silver Member
****

Kudos: 13
Offline Offline

United Kingdom United Kingdom

Posts: 186



Ignore
« Reply #215 on: July 22, 2019, 07:07:07 AM »

There's no replacement for displacement Smiley
Logged
Pages: 1 2 3 4 5 6 7 8 [9]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!