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Author Topic: P-30 in progress--"Titan"  (Read 1443 times)
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Rewinged
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« on: October 11, 2011, 02:09:05 AM »

I've been flying, or trying to fly, a One Nite 28 in P-30 the last couple of years.  I had some success in 2010, but this year I could never get it trimmed because of warp issues.  Anyway, I wanted to build a "real" P-30, and clubmate Marty Thompson sent me the plans for a successful old Bruce Hannah design (redundant--"successful" and "Bruce Hannah design"), the "Titan."  I finally got to start work on it late this summer.  I was hoping to have this completed for our last 2011 contest, but it wasn't to be.  The build is going well, and I didn't want to rush it.  These are the photos of my progress.

Bruce drew up plans for a second version of the Titan, but the 2nd version was never built.  I am building something in between the two, which is why the plane doesn't seem to exactly match the plans--the plans show both versions.  I'm using the structure of the first, but a straight TE like the second.

I'm not an experienced stick-and-tissue builder, so I chose to use the flat-bottom airfoil of the original Titan.  I picked a couple of close foils in Profili, and used that program to get my tapered ribs, thinning toward the tips.  I cut the rib patterns out, and glued them to some 1/64 ply.  The ply templates were cut to shape, reinforced with CA, and then sanded to smooth outlines.  This made it easy to cut my ribs.  The constant-chord section ribs were stacked and sanded to be completely uniform.

--Bill
Attached files Thumbnail(s):
P-30 in progress--"Titan"
P-30 in progress--"Titan"
P-30 in progress--"Titan"
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Rewinged
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« Reply #1 on: October 11, 2011, 02:13:23 AM »

A couple more views of the wing sections, and one with the dihedral added.

Since I am an experienced glider builder, I put the dihedral in like I was building a glider.  I used 2 ribs at each dihedral joint, and made them a bit thicker so that I could sand the dihedral in.  This is obviously a small weight penalty, but it was something with which I was familiar.  I think the plane will come out on weight, or very close, even with a bit of extra balsa at those joints and at the spars.
Attached files Thumbnail(s):
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
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Rewinged
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« Reply #2 on: October 11, 2011, 02:17:21 AM »

I messed up a bit on the stab, and made the rib spacing too small.  I think I'll make another one with wider spacing, and try diagonals from the high point to the TE, to hopefully increase the torsional rigidity.  The current one is not too bad, and is 3.4g covered.

I also rolled my first tube fuselage, and it came out fair, but there's not much to show in the pictures.

The final photos show the wing and stab covered in 1/4 mil mylar.  I plan on using tissue over mylar for the wing.  I may try another stab with a slightly different structure, and leave off the tissue.

Anyway, I am pleased with the progress thus far, considering my lack of experience.  You can see by the photo shoing the wing on edge, laying on the carpet, that it is nice and straight at present.  There is a bit of washout in the tips.

--Bill
Attached files Thumbnail(s):
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
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DaddyO
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« Reply #3 on: October 11, 2011, 04:07:13 AM »

Nice workmanship Bill.

I don't know of the design, but coming from where it does it should be a good un  Grin

FWIW I've found that apart from the tailplane leading edge in the middle, there is very little stress of the rest of the structure for these smaller models.
 On my own designs I just use a couple of 16th sq. spars and 32nd ribs without any diagonals. On the A1's I add a short piece of 16th sq. between the mid point of the ribs to prevent the spars collapsing and tissue cover; everything else is just mylared (occassionally I add tissue or turbulator strips to the top surface) Which is a long winded way of saying that the structure doesn't need to be too strong . . .

Looking forward to seeing the rest of the build
Paul
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« Reply #4 on: October 12, 2011, 04:17:58 PM »

Bill, It looks like your doing a great job on this build.Looking forward to seeing it completed.keep us in the loop.   Bruce Cool
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« Reply #5 on: October 13, 2011, 10:40:04 PM »

Paul,
Thanks for the suggestions.  I'm sure I did over-build a bit.  But I think it will be close on weight...now that I'm not "afraid" of more complicated (for me) builds, I can always re-do if too heavy; I've got all winter.  I considered the retrieving process while building: I think the biggest risk to models, at least for me, is bringing them back upwind after the flight.  And my biggest reason for the mylar and tissue is warps.  It is wet here about 8.5 months of the year.  If I ever get a rubber plane trimmed again, I want it to stay that way!

But I'm not sure how much structure will be needed with just mylar covering...are you saying that your A1s are mostly mylar?  What parts are tissue?

Bruce,
Thanks for the written as well as personal comments. I will do your design proud next year!  (I hope.)  This is enough fun that maybe I'll have a P20, Runt, less breakable Double Take, and who-knows-what ready for next year's 3 Amigos!  Speaking of which, what is the new event going to be next year again?



I'll post again when more progress is made...might be awhile; I'm fixing up my building space.

--Bill
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« Reply #6 on: October 14, 2011, 12:21:00 AM »

Bill,
  It's not for sure but I'm thinking of using some small electric from Harbor Freight like the Gobot and you must use the body and motor but with anything goes type of thing for the wing and stab,what do you think of that idea?Easy and might be fun.    Bruce
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« Reply #7 on: February 16, 2012, 12:22:38 AM »

Probably could have this in the "Show us" thread, but this is sort of a build thread, so I kept it separate...

Finished last week, and flown at the Isaacson at Lost Hills last weekend!

It trimmed very easily, but as a pretty new rubber flier, I didn't get it fully trimmed before the contest, which led to a sort of funny, sad, surprising result I'll mention below. 

Since the last report, I got the wing covered with tissue over the mylar.  Then, as I finished the wing and stab mounts, DT, and other fiddly bits, I checked the CG and estimated the wing location.  With the wing about as far back as reasonable, based on other models and TLAR, I could get it to balance at the desired 65% chord--at the rear-most short spar.  So I put the wing mount there and hoped for the best.

Final completed RTF weight without rubber is 41.5 grams.  For my first scratch build, I was very happy with that!

I trimmed it as follows:
Estimated the (negative) wing incidence I wanted, and adjusted the wing incidence screw to get it.
Replaced the prop and nose assembly with clay to get it to balance at 65%.
Test glided and adjusted stab incidence to get a good glide.
Wound it up and slowly increased turns each flight.
I really didn't have to make any changes during these low to mid power flights.

I almost lost it on my last evening trim flight on Saturday, but found it with the loan of a trail bike from a new friend. 

However, I was disappointed in the climb using 4 strands of 1/8.  I think it was just because I hadn't really got to decent torque, but after chatting with some more knowledgeable flyers, I made up some motors using 6 strands of 3/32 on Saturday night.

On Sunday, since I had little time with other events, I just went for it with the new motors.  I learned that I really did need another test flight at high torque.  The pattern had been very good, but when I got to higher torque...  My first official flight--as I just "went for it" the plane had some massive power stalls and clicked the ground at just 44 seconds.  Oops.  However, it was really only the prop that ticked, and then the model went into a perfect cruise climb and flew for about another 90 seconds before the DT brought it down from a low altitude.  Woulda, coulda, shoulda been a max, but it hit the ground.

I guesstimated the thrust adjustment, and just went for it again.  Since I had already "dropped," I was trying to get back to the glider pen where I actually had a chance to do well.  The thrust adjustment was near perfect, and the plane flew to very high, easy maxes on my last 2 flights.

The Titan came out better than I dreamed.  I should have expected that with a Bruce Hannah design, but I didn't have that much confidence in my building, especially since I was modifying it for a long motor run and an attempt at PGI trim.  But now, I believe this plane will be very competitive.  There might be opportunity to fine-tune the trim, but I think it may already be able to do at least 150 seconds in dead air.  I can't wait for an opportunity to get to a big field again to see what it can do.

A public thanks to Bruce for patiently answering all my phone calls.

Anyway, here's some pictures of my completed Titan.
 
--Bill
Attached files Thumbnail(s):
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
Re: P-30 in progress--"Titan"
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DerekMc
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« Reply #8 on: February 16, 2012, 12:32:12 AM »

Bill, you did a great job with this plane. It flies very well. Good job working through the trimming issues. I look forward to the competition this August!
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« Reply #9 on: February 16, 2012, 09:33:38 PM »

Thanks, Derek!  Yes, August should be fun.  We should have a number of good flyers in P30.  Hope my plane keeps trim so I can maybe be one of them.
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« Reply #10 on: February 19, 2012, 09:52:52 PM »

Bill, that sure is nice.  I love the rainbow wing.  Hmmm, kinda reminds me of my Majestyk wing.   Smiley  Caley
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« Reply #11 on: February 20, 2012, 01:49:02 AM »

Looks very neat - are you flying right/right or right/left with the PGi trim?
John
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« Reply #12 on: February 20, 2012, 11:10:44 PM »

Caley,
I've been using the rainbow colors on all my models for a few years.  Your post triggered my memory and I think it may have been your Majestyk that got me started!  Funny, your colors look perfect, but when I started my colors weren't, and my artistic daughter told me what to use--ended up pretty close to what you have on your Majestyk.  Of course, I'm going the lazy route and using Design Master paints, but they work well. 

John,
I don't know if it is typical PGI trim, but I am flying right-right.  I haven't really optimized it yet, but trying to follow the general PGI concepts for incidences and thrust line.  Seems to be working well, as the model seems to be low drag and have an efficient climb.  I have about 1/16 inch washin in the right main, and about 1/16 washout on the left and 3/32 washout on the right.  Lot of stab tilt--perhaps a bit much--and no rudder.

Whenever I get it out again--might not be able to fly it until August--I'll take some flight video.

--Bill
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