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Mar 01, 2006, 10:44 PM
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Build Log

TMRC 1/4 Scale 1-26B


"Phil,

Thanks, that would be awesome. No one has really commented on this kit or done a full build log since we CADed the parts directly off of the plans and rectified them against each other. I hope you had a good experience with the fit. It could use a honest evaluation on the public forum".

Tom"


As you can see, Tom asked me in a PM to make some comments on his kit. So here goes:

Firstly, these are my opinions only; your mileage may vary,

Secondly, I'm neither a good flyer nor expert builder; just your Joe Average.

After getting hooked on scale with a glass slipper, I thought I'd try an oldie. I lofted out a plan and decided I didn't have enough experience to pull it off. I contacted Tom and explained my situation. He recommended his 1/4 Scale 1-26B. My order came through very quickly, arrived in good shape and contained more than I thought it would in terms of material. Two things that I though could have been included but were not were:

1. A list of the strip and sheet material required to complete the project but not included ( Note - all other bits are included)

2. A few comments or pictures on building. Tom does include Steve Moskal's original AMA article but I didn't find it very helpful. Construction pictures would have helped as well. Confession: I could have done this for Tom as I went but I didn't.

Please note that Tom does not sell this as a "Kit" for the inexperienced builder but as a collection of laser cut parts and has gathered the required hardware for you.

The wood was first-class plywood and straight clear medium weight balsa. The laser cut was clean and true. The fit was perfect. The only trimming I did was to cut out some lightening holes in the forms to reduce weight. Realistically, I don't think I saved an appreciable amount but those large pieces of plywood cried out for holes. I also cut holes in the stabilizer and rudder because of their aft location.

The fuse build itself is straightforward and the only bit that really confused me was the under belly of the fuse aft of the wheel. The spruce longerons on the turtle deck may be a bit of overkill. I didn't use the called for 1/8 dowel on the fuse sidewall as it didn't seem to add any function or significant strength

I put some uni-carbon on top of the spars (I used fir instead of spruce) and covered that with 1/16 balsa just to hold it down. I expect that I'll sand most of the balsa away before finishing. The supplied rod and brass carrying tube is wider than the spars. Some adjustment will be required to fit with the supplied plywood shear webs. Not a big issue and it is obvious so it doesn't cause any problems later on. The trailing edge has a layer of uni-carbon between the balsa. Next time I think I'll use 1/32 ply as it provides more stiffness. I have installed Multiplex Multilocks (purchased separately through Tom) and Deans 4 Pins potted in the roots.

Equipment installation is easy with lots of room to play with. I'm using Airtronics Std for the Rudder, Elevator and Tow Release, Hitec 55s for the spoilers and Hitec 85MGs for the Ailerons. A 1300 Mah battery is heaviest square one I could find at the NW Hobby Show. Switch and Charge plug are located behind the nose cone. The tow release is a homemade pin and bale variety.

The plan and resulting fuse has a 5-degree decalage between the wing and the rear stabilizer. On Tom's suggestion, I contacted Steve Moskal who assured me that it works just fine that way. However, I have set a 2-degree decalage as starting point and will adjust after trial flights. (Using shims on the rear).

I'm now in the final sanding stages and will start covering shortly with SolarTex. Feel free to comment or flame, I'm pretty thick skinned.

Phil in Vancouver
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Mar 01, 2006, 11:02 PM
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Thanks Phil, I think.

I really like.... no, love the tails. Every time I think about the tails on Steve's design they cry out to me to be a scale open framework. This is a good and strong happy medium that I trust was pretty easy to build with the 60 parts we had to cut just for the tails and will look GREAT under solortex in the sun!

Nice work.

Tom
Mar 02, 2006, 12:06 AM
Where's the lift?
dgliderguy's Avatar
Lookin' GOOD, Phil! Keep them piccies coming.

You're going to like the way this one flies. We had one in our club years ago, built by Charlie Harris and Jeff Kasner, and everyone who wanted to got a chance to fly it. It was tame as a pussycat, yet buoyant and spritely.

Got a color scheme picked out for it yet?

Don.
Mar 02, 2006, 12:56 PM
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Don,
Mainly white on top, red and white on the bottoms. I'm going for max visability but don't expect anything fancy. My covering ability is even worse than my build capability.

Phil
Apr 03, 2006, 05:29 PM
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Finally got it covered! Everything is in but haven't adjusted the linkages yet. AUW 8 lbs (a new record for me - 8 oz UNDER advertised weight) Took 9 oz to balance at the spar. This may change after maiden flight.

Phil
Apr 03, 2006, 07:30 PM
Registered User
Man Phil, she's a beaut! I wouldn't discount you covering skills one bit. Is striking and clean and I like it!

Tom
Apr 06, 2006, 10:59 AM
Where's the lift?
dgliderguy's Avatar
Phil,

Very nice! We'll be looking forward to seeing this one fly at Mission in July, yes?

Congratulations on a good job well done.

Don.
Apr 12, 2006, 03:07 PM
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Her Majesty regrets to report the dismise of aircraft N1-26A. While on her initail slope flight, the aircraft entered an uncontrolable spiral at an altitude of 100' and impacted on the tarmac without hitting any other personnel. aircraft or structures.

After 5 minutes of unremarkable flight, roll control was lost, resulting in a decreasing radius left spiral. The pilot was unable to correct with the rudder and elevator. Rapid opposition of aileron control seemed to have some effect but the lack of altitude and proximity of houses precluded further attempts of recovery. The aircraft was given full up elevator in an attempt to induce a flat spin before impact.

Initail incident investigation seems to indicate a jamming of the port aileron in the full up position. Specualtion is that the port wing partially separated from the fuselage causing a loss of control of the port aileron servo. The owner and builder is re-evaluating his choice of multi-locks and deans connectors without positive locking mechanisms.

Phil in mourning
Last edited by Sleeper1; Apr 12, 2006 at 03:11 PM. Reason: Pictures didn't attach
Apr 12, 2006, 09:03 PM
Registered User
I am in shock Phil. Tried to post earlier but the thread was closed. I would think the failure may be due more to the plug as opposed to the choice of Multiplex wing joiners since they are well proven in thousands of models and once snapped, don't release easily.

It looks to be repairable though. Don't send it to the grave. The fuse is the worse but you have a good wing and tails and the broken wing can have the spars scarfed and repaired. Likewise after removing the covering from the forward fuse, it can be made good as new with careful incising away of the shattered balsa sheet and replacment of the broken structural elements.

Good luck and very sorry to see this,

Tom
Apr 12, 2006, 09:40 PM
I feel deeply sorry...
So frustrating when so much work and passion is ruined by the failure of a $1 component.
It looks repairable though,

Fab
Apr 13, 2006, 12:31 AM
Where's the lift?
dgliderguy's Avatar
Another vote for repairable, Phil. Give it a short rest, then start cutting away the covering. I think you'll be surprised how fast it will go back together again.

I've seen far worse than this, that lived to fly again another day, like this one, if you can believe it......
Apr 13, 2006, 04:18 AM
Registered User
Phil,

I am sorry for your mishappening and I would like to encourage you to start the repair as soon as possible (I hate to have debris lying around in the shop and normally start the same day!)

I cannot really perceive on the photo if you FIXED the servo connector on both sides, the fuselage and the wing. If so, this is always vulnerable and therefore I strongly recommend to have always "one loose end" in the harness ( - and it is less work ;-) ).

I do hope that you get the 1-26 back to flying, not the least in order to promote the "quarter scalers" (hear that, Tom? ;-) )

Herbert
Apr 17, 2006, 07:16 PM
Registered User
Phil,

Can you please expand upon what you meant by
Quote:
After 5 minutes of unremarkable flight
before roll control was lost? Can I assume you mean good control response without bad habits?

Also, what was the attitude and relative speed of the ship when you lost roll control? Your servo connetor hypothesis sounds reasonable, but if you stalled in a turn, that might have triggered a spin, which only down elevator and opposite rudder would have cured.

Beyond that, I add my vote for rapid repair. That was one gorgeous ship!

Gerry
Apr 17, 2006, 09:32 PM
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Thread OP
Gerry,
This was the initial slope flight. I had previously done some bungy launches to get the CG into a reasonable range to go for a longer flight. I launched into a 10 kt breeze off of a 45 degree 80' slope. The ship handled tenderly for elevator (I had way too much throw) and was slightly nose heavy. This was expected as I wanted positive control for the first flight. I made several gentle S turns while setting some down trim and gaining some altitude. The roll response was very good and I was thinking: " What a pussycat" I was just about to do a dive test to get a feel for the CG position when I did a left turn but couldn't roll out. Yes, I was flying slowly but this wasn't like any tip stall that I've experienced before. In all honesty, I don't think you could tip stall this model. Opposite rudder didn't seem to be effective. Perhaps with more experience with the model or more altitude, I could have saved it. The ailerons on this plane are a good size and I'm not sure the rudder is capable of offsetting the roll.

The pushrod on that aileron was separated after the crash. Did it happen in the crash or was it the cause? I don't know but I'm leaning towards it as being the cause. The solder joint was separated but there was no indication of a cold joint. Because the plane rolled left that would mean the pushrod would have been in pressure (up position) and then lock. Unusual! I've never had a Multilock release before and refitting the wing after the crash indicated a strong "snap" to re-attach. I just don't know.

I am rebuilding but it's doubtfull, I'll be ready for Yakima at the end of the month. I intend to put locking pins in but retain the Multilocks.

Phil
Apr 18, 2006, 10:20 PM
Registered User
Phil,

I tip-stalled and entered an unplanned spin - TWICE - my first solo flight in the full scale 1-26 while thermalling at a speed I thought was well above stall. (Got my attention!) Given that, and with less than half the Reynolds number at the inboard tip as the root, unless you have equal or greater washout than scale, I'd expect the model to be at least as spin prone as the full scale bird. BTW, the spin recovery on the full scale bird is a snap. I'd expect that to be the case with the model as well.

Given my history, it should be obvius why the thought came to mind. I am glad to hear control was excellent otherwise.

Gerry


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