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Author Topic: New Model - for OS15FP  (Read 6968 times)
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glidermaster
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« Reply #25 on: March 27, 2011, 12:36:15 AM »

Jim is correct, of course. Undecided
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gossie
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« Reply #26 on: March 27, 2011, 05:05:06 AM »

Jim is correct, of course. Undecided

Is he ever wrong? And I mean that in the nicest way. Smiley
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Sandgroper
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« Reply #27 on: November 24, 2011, 07:46:39 AM »

Has anyone tried attaching a pacifier/bladder to a hard tank to give it pressure?,it could be an easy way to make the SLOP model a better dual purpose model for open power etc.The 15LA is also a very good SLOP engine,it is lighter than the 15FP and performance is similar.Mine pulls 19,000+ on a 7x4 APC with 5% nitro fuel fitted with a homemade turbo plug head and pulls the Dixielander up very nicely.Fitting a OS LC3 long reach plug instead of the A3 gained about 1000rpm on the STD 15LA.Replacing the std 0.2mm head shim with a 0.1mm shim will give a little more rpm if like me you like low nitro fuel.
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RobinB
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« Reply #28 on: August 25, 2012, 04:19:55 AM »

John,
As a follow-on from the dialogue about timers:- I was making an extra arm for an existing timer recently,
and found that to get the same stiffness as the existing arms I needed rather thicker wire.
(I have shop-bought piano wire).
Do you (or anyone) know what wire is used in Texas and similar timers?

Robin
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glidermaster
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« Reply #29 on: August 26, 2012, 11:41:08 AM »

It's a good point Robin, 'Real' piano wire is the answer, I think, though bumping the wire up a gauge is OK most of the time.
I replaced the arms on my Seeligs for F1C (as I used permanently attached lines) and found the same thing.

McMaster-Carr is a useful source this side of the pond, at least, for many things that come under the heading of Hardware.
John
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Sandgroper
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« Reply #30 on: August 27, 2012, 09:58:29 AM »

Hi Robin,
would that be the Texas 3F you are modifying/fixing,I have a 3F 111 in the T34,their site says the DT wire has already been beefed up from earlier models,mine are 48 thou.I have found the set of the tip in the scroll can be quite critical.If the arm is too long it tends to grab and stop the timer in the lower grooves,I opened and closed bends gently with two pairs of pliers until the tip of the wire was 1/32 closer to the pivot and this improved things,also the tip should sit inline with the scrolls inner bore when resting on top or it may jump out-any more inward may slow down the timer.The mainshaft in mine has a lot of clearance in the top bush and the rock has to be taken into account when setting the arm.
The 3F 111 is a fast running version and the tip has to cover a large contact point change in 3 mins so I feel the 3F 1 is a better choice as it will use less turns for three minutes.I find long scrolls a pain so I machined mine down to 8.2mm which gives me just over 3 mins with the arm in the bottom groove and use the second function for early DT.


Cheers Phil
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glidermaster
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« Reply #31 on: December 28, 2012, 07:46:19 PM »

November '09 I started this thread - good grief, still no 'new' model. Embarrassed

I have to admit to being stuck at the front of the fuselage, and every time I got the thing out on the bench to work on it, the engine mount nagged at me as being all wrong.
Finally I bought an OS metal 'T' mount, and what a nice product.
So, out with the razor saw, some balsa, ply and epoxy, and this project is back on the right track, even if the schedule has gone out of the window.

Some other slight revisions are being contemplated, but I should be able to get this one done at long last!

John
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RobinB
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« Reply #32 on: December 29, 2012, 02:57:51 PM »

You mean like this?
I have to join you in the confessional, John, as this pic is from a year ago.
The wing and stab are done, and the front end has been glassed since then but I'm stuck
(as usual) at the timer mounting stage.

Solzhenitzyn said "Two things rob people of their peace of mind: work unfinished
and work not yet begun".

He got that right  Undecided

Robin
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glidermaster
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« Reply #33 on: December 31, 2012, 03:27:30 PM »

That's about it, Robin.
Here's my current status; tank in, pylon advancing, timer area almost ready for timer.
Quite a bit of progress.

Wearing my Dixielander T shirt today, in memory of old George.
John
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glidermaster
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« Reply #34 on: January 15, 2013, 10:59:46 AM »

Some changes to the initial plan, and some progress.
I have been flying a number of all-locked-down models for several years, and on our small field there are some problems; in particular, glide circle.
My models at least, can wander a bit on glide, and as soon as they do, they're off the field, so I'm changing this model to have auto rudder and VIT.

I have built an internally sprung fin/rudder - weighs about 8gms as shown, which is a bit on the high side.
Anyway, that's a first for me, all my other models have external springs to the rudders - aka elastic bands!

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« Reply #35 on: January 17, 2013, 10:18:32 AM »

Hi John,

Where did you get your OS metal mount from as I was thinking this would be good for the two Cresendos that I still have yet to finish but other things got in the way.

John
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glidermaster
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« Reply #36 on: January 17, 2013, 11:21:17 AM »

John,
Check out eBay - item no. 290490942679
That is what I bought, and where I bought it.

John
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FF Bruce
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« Reply #37 on: January 17, 2013, 09:20:14 PM »

John,
   That does seem a little heavy for an auto rudder,8 gr. way back there.I don't think the ones I use weigh more than 2gr. if that.What do you think is making it weigh that much?Is that a brass hinge? 
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glidermaster
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« Reply #38 on: January 18, 2013, 12:54:39 AM »

It's a brass tube hinge, Bruce.
The 8 grams is the whole fin, of course - and it's solid sheet - which might need to be revisited.........
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« Reply #39 on: January 18, 2013, 11:35:49 PM »

So sorry John,I must read things more carefully.I thought you talking about just your auto rudder.My bad Undecided
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glidermaster
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« Reply #40 on: February 01, 2013, 12:19:09 AM »

No problem Bruce, I kind of guessed!

More progress - the fuselage is all closed up, and I'll be putting finish on it next.
The pics were taken on an antique tip-top table I've been restoring, and with which I am quite pleased. I just need to turn up 2 brass hinge pins, and it's done - the table that is.

John
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RobinB
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« Reply #41 on: February 01, 2013, 01:12:29 PM »

Is the hole nearest the front for a bladder, John?

Robin
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glidermaster
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« Reply #42 on: February 01, 2013, 01:46:52 PM »

No, it has a hard tank/crankcase pressure Robin.
The hole is the exit point for both feed and pressure. The tank can be removed fairly quickly by cutting the bottom of the fuselage.

It sort of indicates I don't have much faith in my soldering, perhaps!

I am liking the look of this model again, and I am contemplating scaling it up for an old OS25 FSR of my Dads, but maybe I should fly this one first.
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gossie
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« Reply #43 on: February 01, 2013, 03:37:02 PM »

I like the  fuselage shape JB, and also of course hard tank on crankcase pressure..........in fact I'm only a few weeks behind you on a 40 ship.........wings first, and a pic next week.
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glidermaster
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« Reply #44 on: February 07, 2013, 11:01:58 AM »

We achieved a bit of a landmark last night - the first time the model has been together.

255 grams as shown (no engine, no timer).
John
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« Reply #45 on: February 07, 2013, 11:10:30 AM »

John, love the lines of your plane. Can't wait to hear from you on your flying sessions. On another note I built a 585 Galaxie with an OS 25 FSR with a 9 x 3 APC prop and it was pretty darn fast! I ran it without a venturi, on bladder pressure, and 35% nitro!!!

Scott
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« Reply #46 on: February 07, 2013, 03:50:54 PM »

Niceeeeeee JB. Smiley
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RobinB
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« Reply #47 on: February 07, 2013, 04:58:28 PM »

Looking good, John.

That's a good weight bearing in mind that motor mount must have added some.

Will you have the CG further forward now that you've fitted V.I.T?

Robin
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glidermaster
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« Reply #48 on: February 19, 2013, 12:18:53 AM »

The original model has quite a chunk of lead under the tail (see pic.) to get the CG back to about the front of the trailing edge, and it still needs to go further. Simple answer is yes, I'll be looking to get it forward to about 70 to 75% back from the leading edge.

First coat of paint just went on the fuselage - not much point taking a picture of that, though!
John
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glidermaster
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« Reply #49 on: March 20, 2013, 02:29:01 PM »

I think I'm going to call this one a done deal now. The next reports will be from the crash-site - er - I mean flying field. Cheesy
Just an address label, some fuel proofer, and some lines to the timer to go.

Weight has crept up to 15.75 oz. (450 grams) which is more than I wanted, and CG is a concern at 78% back (root chord). Depending on flight tests, I might size it up for one of my G.15s - that should make it a bit more exciting!

John
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