HW50

Hi,

A few years ago i bought a David Andersen Drabant 2,5 on Ebay. I wanted it since I had one when I was 15 years old, which is 48 years ago.
The engine is of the first kind of DA with twin BB Construction, which was delivered with an aluminium spinner. It might have been produced in the late 50's.

C/L flying is seeing an increased interest in my region, although mostly between People my age.
I want to build and fly a C/L plane with it, most probably it will be a kind of semi stunt plane without flaps.

I have now tested it, this is the result:
Prop: 8x6 of the yellow, rather soft type. I think it is a Tornado.
Max. rpm: 10,290

I got the fuel via a model airplane friend, and don't know the origin. However I think it is British, and most probably has IPN in it.
I could relieve the comp screw a little when it got hot, much like it was with Amyl nitrate back then.

When Cold the compression is very good and tight, Seconds after a full power run it will leak out. I can however restart it without problems when it is hot.

Does this sound like an engine suitable for flying?

Thanks for you Help,
Helge.

brokenenglish

Helge, it depends on what you want to fly...
Of course the engine will be OK for flying if you have a lightly loaded old free-flight design flying as RC assist.
Almost all my flying is like that, and I mostly use old engines that are not running at max. performance.
Just avoid heavier, faster flying planes that need more power and you won't have any problems.
I never worry (or even think) about "max. rpm" with any of my planes, just use a good reliable old engine, that's well matched to the plane,and it will fly OK!
At the moment, I'm flying at least three old dieselsthat are older than your DA.

brokenenglish

Maybe there's something wrong with the system. I've uploaded a wrong image (apparently) and I'm unable to edit anything. There's no edit button!
I meant to show this Simplex, flying with a late forties Micron...

PWF63

Hi Helge

gossie

For Controline you might want to take a look at BLUEPANTS. It's a CL model that suits a 2.5 diesel of your one perfectly.

Several of us have them here and fly them for fun with mostly older engines in them.........Mine has a CS Oliver.

jfuller

My Feedback: (8)

Hi
Where would one find BLUEPANTS plans?

Thanks,

JamesF

greggles47

Helge,

I must ask first if your engine was new when you received it? If so, it may take a bit of running to settle in. There are many threads on running motors in. Once done the compression should hold better and produce more power.

For fuel, I'd recommend the Oliver brew, 20% Castor Oil, 30% Ether & 50% Kero. to that you can add whatever amount of ignition improver is dictated by local conditions. If, like many others around the world, you have trouble sourcing the required fuel components, look to local clubs where diesels are being used.

I wouldn't recommend that you keep using that old prop. There have been many cases of blowing blades off those. Modern props are much safer.

Like the others, I'd recommend either the Peacemaker, or the Blue Pants.

Good Luck

Greg

qazimoto

My Feedback: (1)

James,

if you PM me your email address then I'll send you a scan of the Bluepants plan.

I've posted it on one of the forums so it may be on Outerzone of Hippocket by now as well.

Ray

greggles47

Blue Pants is on Hip Pocket.

Looks just the job for a vintage style motor.

G

HW50

Hi all, and thank you for your helpful answers.

The engine was used when I bought it, and has obsiously seen some running.
I could see the prop was flexing, and would not consider using that one any more. It was just lying in my hobby room when I needed it.

I found and downloaded the Bluepants drawing, which seems a quick and nice build. Maybe this is the right one for me.

To me using a diesel is a point in itself. I have most kinds of R/C Aircraft, which by now is either glow, gas or electric.
Just smelling and listening to the DA told me to follow this path until I get a plane in the air.

I'll do so some more test runs while I am building a plane for it, but I feel that this engine is up to the job.

Helge.

gossie

More BLUEPANTS pics to keep you interested.

I built mine to the plan 4 or 5 years ago now with a little right rudder on it to keep it tight on the lines, the plan shows zero rudder and no out thrust, but to me it felt very light on the lines, so I added right thrust on the engine and it's much better.
After out last session with them a month ago a friend who has the yellow one with an ED Racer had a fly of it and suggested it felt rather nervous and that the C of G needed to be further forward, so last week I pulled the motor out and glued 30g of lead in the front under where the engine goes.
I'm not a very good CL pilot, but do enjoy flying them now and then, so with a little luck that should fix it. The C of G is now about 25 to 30cm behind the leading edge as a guide for you.

steve111

In which case it might still be a bit nervous-feeling, Gossie!

gossie

Just testing. LOL. MM of course. As a matter of interest Steve, where does yours balance please?

steve111

Mine's about 35mm back from the LE and flies very nicely like that, so yours ought to be fine now, Howard.

Helge, the Blue Pants is a nice flyer and ought to go well with your engine, but I wouldn't discount the Peacemaker. There's a bit more work in building the Blue Pants, although it's not exactly complicated. Also, you'll probably have to make your own tank for it, and once it's installed and the fuselage is complete, you're pretty much stuck with it. When the engine is a bit of an unknown quantity, it's nice to be able to adjust or change the tank, and this will be quite awkward with the BP. You could always put a hatch on the LHS, but that's more complexity; besides which if you build as per the plans, the back of the tank sits in a cutout in the wing LE sheeting, which makes adjustment/removal harder again. Whereas the Peacemaker is a much simpler build, being a profile fuselage, and it's very easy to do whatever you need to with the tank to get a good engine run.

Anyway, they're both good flyers, so good luck with whatever you choose to build.

Steve

HW50

Thanks again,

Having built several planes before, I think one of the mentioned planes should be an ok build. In my younger days it was the norm to solder the tank from sheet brass.

I am still a bit in the dark when it comes to performance. We had a tachometer in our club, and I seem to remember our Olivers did in the region of 13,500 - 14,000 static rpm on a 8x6 prop, with approx 15,000 rpm for the quick ones. I never tested my DA then, but I remember from the sound of it that it was not that strong. Maybe 10,300 rpm is an acceptable figure for that engine. I never had any other brands, so I have no knowledge of what would be a weak / strong engine. Also, of course there would be differences between fuel mixes, and the prop brands with similar dia/pitch spec.

Helge.

steve111

I don't have an Oliver, but I'd be very suprised if one could manage 13500-15000 with an 8x6. I think you'd be doing well to get much more than about 12000 out of a good 2.5 diesel with that size prop. Perhaps those figures were for an 8x4 or 8x5?

10300 sounds pretty reasonable for your Drabant.

qazimoto

My Feedback: (1)

My well run in MOD Oliver Tiger mk3 turns a RAM 8x6 at exactly 12K rpm.

An APC 8x5 suits it much better in a Peacemaker.

Ray

HW50

You are right. I guess my memory paints the old rpm figures in too bright colours.

However, this makes me think that my Drabant may be in good shape.

We always knew the Oliver was the stronger of the two.

Thanks,
Helge.

qazimoto

My Feedback: (1)

Your Drabant may do much better on a modern 8x6.

Ray

Lou Crane

I had a D-A .15 diesel back in the 1950's. It went onto a first release Goldberg Shoestring profile. I was 'just a kid' back then, so it flew on TopFlite 10-6 wooden props, and about 60' of 0.018 cable lines. ...On a black U-Reely... Fuel? Two commercial fuels were available: OK Cub and McCoy - since they both sold small diesels then, too. Later, found some tech ether and brewed my own, pretty much 1:1:1 blend. Worked great!

The Shoestring Profile is about the size of the TF Flite Streak - fairly large and draggy for a 2.5 diesel, more so on such a prop and such heavy lines. Never pulled real hard, but never fell into the circle, either. Did the stunt pattern as well as I could then, anyway. Laptimes were leisurely, possibly 6.5 to 7 seconds. Wingovers, in particular, were a trip.

Nice purring steady sounding level flight...Pulled up to vertical and the engine "pooted" once then settled back to usual. About 4 seconds later, turned from vertical back to horizontal (eiher way!) and it again "pooted" once. Didn't seem to change its 'tone' on smoother maneuvers, but I don't recall whether it did anything odd on square-figure corners. But, again, it hung out there very dependably througout the flights...

(Translator's Note: For anyone unfamiliar with the term "poot" it is a way to describe a clearly audible flatulence. Oh, well, call it what is was - a loud fart.)

You should have a good time with the Blue Pants and a better combination of lines, prop and fuel!