Simple pleasures

Everything retro I.C.
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Stew
Posts: 495
Joined: 02 Mar 2018, 10:21
Location: Staindrop, Darlington.

Simple pleasures

Post by Stew »

Popped out to the garage this morning to breathe life into a little DC Merlin I've been cleaning up after purchase. Hadn't been run for aeons.
Did the needful with comp screw and needle valve, quick prime in the port, a few flicks and away she went. Pappada pappada pappada at first and then gave it some compression and a tweak, faaaaaaaaaaaaaaaaaaap, and back down again pappada pappada. Ran two tanks through it.
Lovely. Garage smells great now, and so does my fleece. I feel like I've snuck outside for a sly smoke or something. Neighbours will wonder what the hell the noise is too. What is that idiot doing in there?

A nondescript engine, in a small garage in the back lane of a nondescript terraced house, but what arcane chemistry and ancient rituals are played out inside! Strange noisy devices running on substances frowned on or beyond the ken of the busy and non-modeling normal folk. Castor oil. Ether. Names that call from the past like the faint bellow of a distant dinosaur. Odd smells, muttered incantations, rhythmic sounds, faint smoke issuing from under the door...and inside a hunched figure with gleaming eyes, caught up in the ceremony, oblivious to all else....

Stew.
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PaulJ
Posts: 598
Joined: 16 Feb 2018, 19:01
Location: Ipswich, UK

Re: Simple pleasures

Post by PaulJ »

Very nicely put Stew, I'm sure we can all identify with that :P .

Unfortunately my own nostalgia trip this morning wasn't quite so successful.......

It crashed.......

Again! :cry:
Stew
Posts: 495
Joined: 02 Mar 2018, 10:21
Location: Staindrop, Darlington.

Re: Simple pleasures

Post by Stew »

Ah...What crashed, and how'd it happen? Repairable or was it a bin bag job?
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PaulJ
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Location: Ipswich, UK

Re: Simple pleasures

Post by PaulJ »

The model was (and still is ;) ) the "Timber" which I built as a first go at Galloping Ghost. On it's first flight a few days ago, it didn't have enough control response, I have increased the size of the rudder and increased the elevator movement but still full left rudder was not enough to prevent a slow right turn and the elevator response was not enough to stop a gentle descent into terra soggy. Damage was only slight and it will fly again but I need to do something fairly positive to improve the control response before trying again........
Stew
Posts: 495
Joined: 02 Mar 2018, 10:21
Location: Staindrop, Darlington.

Re: Simple pleasures

Post by Stew »

Hmm. It has a flat bottom wing section, so should climb under power. Does it glide OK from a hand throw? perhaps a bit of packing under the L/E of the tailplane to increase the incidence slightly. The fin looks OK on the plan with a nice long strake in front of it too. Rudder looks fine.
Balancing OK and side/downthrust angles all OK? Did the build come out close to plan weight?

I'd be very interested to know the outcome. Pleased it's still not matchwood!

Stew.
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Wayne_H
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Joined: 17 Feb 2018, 05:26
Location: Temora, NSW. Australia
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Re: Simple pleasures

Post by Wayne_H »

Stew,

Great imagery - only thing that stopped me from immediately racing out to the shed, muttering the appropriate incantations & snorting ether, kero & castor oil fumes again was the time & distance required to travel to the storage unit where all my diesels are packed away :(

But, give me a month or two................
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
Twitcher
Posts: 53
Joined: 16 Feb 2018, 12:17

Re: Simple pleasures

Post by Twitcher »

Hi Paul
Your GG woes sound familiar! I don't know the flying characteristics of Peter Holland's "Timber" but there are a few dodges you could try to improve things.
1. I couldn't make out the Balance Point on the plan but, assuming it's somewhere around 30 - 33% of the MAC, you could re-balance just a little further back, say 35/36%. This will encourage the model to climb from launch or takeoff. It also means you'd be inputting a bit of down elevator for straight and level flight, which helps to damp down the galloping and also, because it usually increases airspeed, improves rudder response.
2. Don't be afraid to increase rudder and elevator areas by as much as 50%. GG control is NEVER going to be as sharp and responsive as modern digital gear! You have to learn to live with that. Bigger surfaces help, unless you're flying a "Wagtail" or "PhleetPhoot", which were both designed for racing and hence very fast and responsive to the controls.
3. Aim for about twelve degrees of "down" and thirty to thirty five degrees of up. Rudder should again be about thirty five degrees both ways. If you're using a Tobe Rand, these numbers will probably mean you'll have to arrange for the control horns to be very close to the hinge lines.
4. Make sure your linkages and hinges are as free as they can be. Proper balsa/wire pushrods and leaf/pin - type hinges are best. These little actuators have to work hard so they need all the help they can get!

Hope this helps.

David
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PaulJ
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Location: Ipswich, UK

Re: Simple pleasures

Post by PaulJ »

David, thanks for your tips. As it happens I have done more mods and test flew it just a few days ago. As you can see, I have more than doubled the size of the control surfaces by (as a temporary measure) adding some bits of Depron to the trailing edges........
IMG_0465.JPG
It's not right yet but at least I did manage one flight and got it back on the ground in one piece! I was under some pressure of time so I wasn't able to make the adjustment on that occasion but it needs some down trim which when added will I think make the elevator trim much as you describe. It is difficult to measure control surface movement when they are all waggling about! However I think the rudder is probably not far out on your suggested 35 degrees and I might need a bit more elevator movement. As I said, it does need some down trim but the biggest problem was a marked pitch UP when I applied rudder in either direction. I wondered if it might be due to the swept hinge line causing the rudder to act as an elevator??? I'm not sure what I can do about that but I thought I would sort out the elevator trim first and then see what it's like........

Thanks again for your input.

Paul
Twitcher
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Joined: 16 Feb 2018, 12:17

Re: Simple pleasures

Post by Twitcher »

It's good you got a full flight with the Timber. I have a now-elderly Veron "Robot" that also has a swept fin. There's no problem with control interaction, but then, it's got a Controlaire "Ghost" actuator in it, which seems relatively free from it.
I assume you're using a Tobe Rand? You could try reducing both the aileron and elevator travel at the transmitter to 50%, then watching to see how "clean" the movements are on the model. If there's no or very little interaction, you can increase the percentages in small increments until you've gone as far as you can. You might not be able to eradicate it completely though . . .
My experience with a number of GG models has been that all have needed a fair bit of fettling (I.e. trimming) to get the best out of them. There are some that will never be much good - the Vic Smeed "Chatterbox" is one: it does fly, but it's got quite a high wing loading, which, as it has to fly quite fast, tends to make it squirelly. In fact, it's very aerobatic! A better size and wing loading for GG appears to be around 42 -48" w/s and 12 - 15 ozs/sq.ft.
Keep persevering - you'll get there!
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PaulJ
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Joined: 16 Feb 2018, 19:01
Location: Ipswich, UK

Re: Simple pleasures

Post by PaulJ »

Yes it is the Tobe actuator that I am using but I am sure that is working as it is supposed to. I think the problems, such as they are, are due to the model, which was not originally designed for GG and with my own lack of GG experience. I had to add an elevator and guess at size and how much control surface movement to use and I didn't get it quite right but as you said....... I'll get there ;) .
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