Britkit Build Off 2012 - Mercury Mars - Plans Published, see post #90 - Page 5 - RC Groups
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Aug 25, 2012, 01:39 PM
I like real wooden aeroplanes!
Sundancer's Avatar
Thanks Owl. Should be slowish as the wing loading is light but I think that I have over done the power a bit as, at full throttle, It will have 130 watts per pound! Still, the loud pedal is under my left thumb and a bit of a reserve of power is always nice to have.
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Aug 25, 2012, 01:41 PM
TLAR Aviation
Harry D's Avatar
Just beautiful, as always, George.

Do you have any tips on applying cabin "glazing", for someone who is about to start his Britkit build, hasn't attempted glazing for over 50 years, and is convinced he is going to totally mess it up?
Aug 25, 2012, 01:58 PM
I like real wooden aeroplanes!
Sundancer's Avatar
Thanks for the kind words Harry, but regarding glazing I think you are asking the wrong guy! Over the years I have seen some outstandingly good examples of glazing, unfortunately none of them were mine! Despite over 60 years of trying and literally hundreds of efforts, mine are usually - well - no better than OK.

All I can say is; take your time. The photo below is of the FOUR templates I produced for the Mars windscreen before getting one that was acceptable.

If I remember rightly you are building a Dandy? That has an "all round" glass house so you have double the problem with a front and rear screen. You might try using doculam for the flat side windows, for the screens there is really no substitute for paper patterns until you get one right.

Another problem is sticking the stuff on. Lately I have taken to using Balsaloc and then applying GENTLE heat - low enough to not deform the acetate but enough to re-activate the Balsaloc.

Best of luck!!
Aug 25, 2012, 02:26 PM
TLAR Aviation
Harry D's Avatar
Thanks, George. Yes, it is the Dandy I'll soon be starting on (had the plans for a while, but life got in the way as it so often does).

I didn't really think there was any "magic bullet" for glazing, but I'll try your suggestions. I probably couldn't have chosen a worse subject for a (sort of) first attempt at glazing - full wraparound, everything tapered, curved and sharp corners, very small and fiddly for my fat old fingers...

But a bit of a challenge, which is not a bad thing. We will see.
Aug 26, 2012, 04:02 AM
I like real wooden aeroplanes!
Sundancer's Avatar


One thing about model flying, it always has a way of bringing you back down to earth! Since the handling issues which I had to sort out with the Tomboy I have enjoyed a straight run of six models - Bantam, Tom Tit x2, Zephyr, Mamba x2, Witch and Sportster - which have flown straight off the board and have not even required the most minor of tweaking.

At 8 am, it was bright and calm, Ali was available so it was an ideal opportunity to do the first flight of the Mars and get some airborne shots. The model was checked, CG just forward of the calculated position, no warps, plenty of power, what could go wrong. Well, two seconds into the flight I found out! The model reared up showing every sign of significant tail heaviness, as is always the case with an aft CG rudder inputs caused "lock to lock" and the model hit the ground 20 metres away. No significant damage, just a broken prop and the front dowel pulled loose. Plus one very puzzled pilot and one equally puzzled photographer - "Why did it do that?" she wanted to know "your models ALWAYS fly OK."

Whilst my wife's faith in my abilities is touching it was also clearly misplaced in this case, so, back to the workshop for a little repair and a think. In deciding where the CG had to be I had referred to the marked position of the original F/F rubber plan, then worked out where it should be for an R/C model as if it were a normal biplane. Clearly this isn't going to work for this layout, which is really more of a sesquiplane, so I recalculated it on the basis of a high wing cabin model, ignoring the lower wing and setting the position at 35% of the top wing chord. This required 3/4 ounce of lead in the nose. Damn! If I had put the servos in the cabin instead of the tail it would have been perfect!

So there it sits, damage fixed and CG adjusted, unfortunately (9:45 am) the wind is now blowing again, so, maybe this evening if it drops off. Meantime I can nurse my wounded pride and reflect that this aeromodelling business is not quite as easy as it may seem.

Ali apologises for not photographing the crash: "Well", she said, "I was just waiting for you to sort it out, I'm used to seeing your models doing all sorts of gyrations but they never crash!" I can't work out whether this is a condemnation of my flying or a compliment!
Aug 26, 2012, 04:13 AM
Registered User
owlsabie's Avatar
Sorry to hear our maiden didn't go well I'm glad the damage was easily fixed, and good luck for the next attempt!
Aug 26, 2012, 06:09 AM
Sic itur ad Astra
sparks59's Avatar
Ooops indeed George!
Sorry to hear your brief tale of woe on the maiden. It does already look to have a tail down attitude in the photograph where its 2 metres from your hand.

Anyway, it sounds like you escaped the ignominy of returning with an ASDA (or maybe Carrefour) bag full of balsa and tissue, so, with a lump of plumbers revenge taped to the nose, the dowel refixed and a new prop fitted, the Mars is ready for the second attempt.

As usual, we'll be wishing you the best of luck and hoping to hear news of a better, nae wonderful, flying experience very soon.
Aug 26, 2012, 02:53 PM
I like real wooden aeroplanes!
Sundancer's Avatar

Normal service has been resumed....

....after this mornings embarrassing fiasco, the wind co-operated and dropped this evening so out we went again with the re-balanced Mars.

Absolutely no problems this time, it is a pussy-cat, what a difference 3/4 ounce of lead makes! Great speed range, cruises at about 1/3rd throttle, as I expected it has power to spare, it would fly happily on half the motor, but it is nice to have a reserve and I did a couple of spiral climbs to 500 feet or so which were quite impressive. Despite the small size of the rudder, the response is very rapid, elevator is quite nice and gentle, but it will loop ad infinitum and barrel roll. Haven't tried the spin yet.

Ali was all set this time to photograph the crash if it happened, she was quite disappointed but made up for it with a nice selection of shots.

So that's another Britkit build put to bed. I enjoyed it.
Aug 26, 2012, 03:33 PM
Registered User
owlsabie's Avatar
Fantastic So glad she behaved this time out She looks a treat in the air, great photos

Now for that Black Magic?
Aug 27, 2012, 03:56 AM
Sic itur ad Astra
sparks59's Avatar
Great stuff, congrats George.
The Mars looks great in the air.
Lovely pictures too, so well done to Ali the snapper.

Aug 27, 2012, 07:48 AM
The dog ate my clearance
brokenspar's Avatar
Glad you got it sorted out. Sure is a great-looking model.
Aug 27, 2012, 07:52 AM
Blueplaidcanard flyer
Now I have another for the build list!
Aug 27, 2012, 08:44 AM
I like real wooden aeroplanes!
Sundancer's Avatar
Thanks guys, glad you like it. It is a bit of an odd one, but does have charm in the air, I had another flight this morning before the wind got up, due to flying almost all the time at half throttle or less I am getting over twenty minutes from the 1300 lipo so I reckon it must be cruising around on 40 watts or so, it certainly climbs like a scalded cat on full throttle, or, if you hold it down, it is disconcertingly fast, which doesn't look right - bit like a vicar in a Ferrari!
Aug 27, 2012, 08:51 AM
albyone's Avatar
excellent result!


Aug 27, 2012, 03:34 PM
Registered User
Sky Jiver's Avatar

Nice One George

Nice One George which leads on to, What are you gonado next ? Brian M.

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