SHORT SOLENT MARK IV – 2014 WINTER BUILD

[piker]

Nice!  Lot's of nice, fresh wood to start the winter build!

[wollins]

After a lot of research, I've decided to either go with the OMEGA 870 motors or the TURNIGY G-25 870KV motors.  The Omegas are better but twice as expensive so I'm leaning towards the Turnigys. Will also be using Turnigy Nano 4S 3000mah packs.

My numbers work out to:
41A x 15V X 4 = 2480W = 165w per pound at my goal weight of 15lbs. I'm estimating this should yield about 9 minutes of scale fight.

Colin

[wollins]

Oops I meant G32's. (was looking at the wrong note)  So the correct numbers are:

33A x 16V X 4 = 2112W = 140w per pound at my goal weight of 15lbs. I'm estimating this should yield about 11 minutes of scale fight.

[piker]

140w/lb = SCALE FLIGHT?!!!!

40w/lb would offer scale flight   

[wollins]

Quarter throttle is for flying/cruising.  140/watts a pound is for taking off from grass. (and 2015 nooner racing ) 

[wollins]

Trying to source spinners with the scale shape I'm looking for and coming up empty. Can anyone help? They kinda/sorta look like a P-51 spinner shape in that they're somewhat more "blunt" or rounded at the ends. (see pics)

Colin

[piker]

I guess you'll have to make your own.   

[wollins]

Damn, I hate making spinners. It's gonna be a particularly big PITA cause I'll have to get all four perfectly similar.

[wollins]

Ok so my goal is to make this as scale as I possibly can. (more so than the CL- 415) I'm talking panel lines, rivets ... the whole nine yards. Most importantly though ... is to get the right scale shape and profile. Ivan's planes are well known for how great they fly and how light they are ... however they are equally well known for not being very scale. 

The first pic is an example of a typical Ivan's Solent's nose.  The left image in the second pic shows Ivan's rudder going all the way down to the fuse whereas the full size's rudder (right image) does not.  The sharp lines of the nose of Ivan's Solent shown in the first pic, extend throughout the whole plane.  This makes it somewhat boxy looking and generally very angular. I'd like to achieve the smooth rounded curves of the full size. (also shown in the model in pic number 3) 

So what does this mean in practical terms? Extensive modifications. And what does that entail?  Much pondering ... which means time ... lots of time.    Brace yourselves for another long one and hopefully the finished product will make up for the possibility that I will bore you to death along the way.    A little bit of a concern though is there is a definite weight penalty that comes with extensive modifications, but I'm confident that I'll be able to keep the weight of this one respectable. Here's why.

Ivan's Solents (the 100" span ones most people build with his plans) come in between 7.75 and 9 pounds.  At 1200sq inches that's like a kite! lol! That's the Wing Cube Loading of 5.2 which is just outside the WCL range of a glider!  IMHO a respectable weight for a plane this size is around 15 to 17lbs. Even at the high end of that range (17lbs) it's still only at a WCL of 10.6. So, the good news for me is that I have an "extra" 6 to 8 pounds to play with. (knowing me I'll probably use every ounce of those "extras"!) 

Having said that my AUW goal is 15 pounds.  Now that I have had the experience of the CL-415 build it's helped me to come up with that goal weight for the Solent.  Here's how.  The plans for the 415 were loosely based on the "style" of an Ivan Pettigrew build. The guy who designed it (Mike Roach) was/is a big fan of Ivan's designs but Ivan didn't have a plan for a 415 so Mike decided to design the plan himself. That's the CL-415 that I built.

Since Mike adopted a lot of Ivan's design style and techniques in his 415's design. it too was supposed to come out really, really light.  In fact the plans call for it being at around 4.5 lbs! My AUW eventually ended up being 8.6 pounds.    Before you freak out here's the thing. Again, like the Solent, at the 4.5 pound suggested weight the 415 would have had another kite like WCL of 6.3. Even though my 415 is NINETY ONE POINT FIVE percent heavier than suggested, it still has a more realistic WCL of 12.1 and it actually still flies "light", (like a trainer almost.)

So ... (bear with me now, you know I can be long winded! lol!) if I extrapolate the 91.5% overage to the Solent, I still only come up with 14lbs 13ounces. Ok fine, everyone knows that nothing works out in reality like it's planned on paper but a fella has to get his goal numbers from somewhere, right? lol!  Joking aside, there's a good reason why I think I should meet or better the 15 pound goal.

The 91.5% overage that I experienced with the 415 was based on the fact that I made a lot of mistakes due to inexperience. This lead to almost all of my overage weight wise. Yes I modified the plane somewhat extensively. For example none of the following were called for in the plans:

1. I added an inch to the wingspan.
2. I added flaps. (with their associated hinges and connecting nuts and bolts and extra servos)
3. I strengthened the wing.
4. I reinforced the fuse.
5. I added real wheels on the sides of the fuse
6. 1 added a lighting system

However I think a good portion of the extra weight was due to the fiberglassing,

See the plans had only called for sheeting the fuse below the water line and then covering it! I sheeted, glassed and painted the entire fuselage. That with it's associated filling and epoxying and painting I would bet put on a lot of the extra weight. If Robert told you the story of my "mudding/sanding" technique associated with drywalling you'll understand why I think here's where the weight piled on! lol! 

In any event, the plan this time is just to sheet, FG and paint the bottom one third of the fuse, (just above the water line down) and the bottom 1/3 of the tip floats. (of course that's the plan ... as of now. )

Colin

[wollins]

And the nose's profile is wrong too.

[wollins]

Also no flare in the chine rails like the full size.

[wollins]

The postman dropped off a tree in a box today! It's not the 1st yet but ... should I start?     

[battlestu]

can't hurt to open it up

[piker]

Nice!  An exciting time for sure.  I love the smell of new balsa.  It get's the creative juices flowing   

I haven't built with balsa since April.  I'm going through withdrawal!!

I know Michael is itching to get going on his flying boat build, and I'm looking forward to getting back to the Stranraer.

[sihinch]

Where do you order your balsa from, Colin?