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Author Topic: Heatwave  (Read 2087 times)
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RobinB
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« Reply #25 on: October 20, 2010, 06:08:17 AM »

John
Mike Green's ETA 29 model was the Hellbender, a Model Aircraft plan around 1960/61 - a very good model.

There's another Mike Green model in the 1959/61 FZYB. It's just named as 5cc Open Power, but perhaps it's the one Paul refers to.

Eta 29, A/R, flat-bottom wing section, low (3:1) A/R stab, 64x8 wing with the same tip dihedral as Heatwave.

There haven't been that many power models that only have tip dihedral.

Robin
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« Reply #26 on: November 01, 2010, 04:42:51 AM »

Further progress...
I''ve been getting on with the fuselage so now it looks like a model. I opted for wooden engine bearers as per the plan in the end. It was too much hassle trying to work out how to mount and attach a firewall without completely redesigning the front end of the model.

I saw the engine installation on my flying friend's model and he had a fox 19 on wooden bearers with the engine in the same place as per plan. This got the c of g as per the plan (with a little bit of trimming weight in the tail end). He'd incorporated a few degs downthrust plus a bit of left thrust using a couple of washers. I'm going to set the OS 20 up the same.

 First I have to cover the flying surfaces to enable me to find exactly where the engine needs to be for correct c of g, then I'll finish the nose area off to suit. At the moment the bearers are left long to give the adjustment. I don't think its going to be too far off from the plan c of g.

There should be a couple of photos attached. I particularly like the rear 3/4 view as it shows the clinical working conditions in my modelling room at the moment to full effect! I promise to have a clear up before starting on the covering.
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« Reply #27 on: April 04, 2011, 04:26:43 PM »

Hi Everyone,
The Heatwave is finished.
I took it out to Middle Wallop a week or so back, but couldn't get the engine to start. It was the first time trying pressure fuel feed. I got the engine to fire a couple of times but it wouldn't pick up and run. When I get round to trying again I'll try a different plug, the one in the engine is a random one that came with the engine when I got it. I hadn't run any of the other engines I'd bought before bunging them in models and they all started straight away. If the change of plug (to a standard OS no Cool doesn't work, at least I've got two other brand new OS 20fps. I'll just put one of those straight in.

I did a few test glides and the model was a bit over elevated, despite taking care to get the c of g very close to that marked on the plan. I need to build in some reduction in wing incidence before next attempts. The model came out at 19.6 oz. Maybe if the weather is good this weekend I'll give it another try. In the meantime I'm taking a slight break from FF power and am building a control liner, but that's another story.

Cheers,
Adam
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glidermaster
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« Reply #28 on: April 06, 2011, 06:21:33 PM »

Nice work, Adam - very nice!

Concerning your description of the engine not starting; it is unlikely a change of plug will have much effect (in my opinion, I hasten to add). The wrong plug might cause poor running, but assuming the fuel is appropriate, and fuel is actually getting into the engine, it is unlikely to be the cause of no running.

A plug with a faulty seal is a possibility, but in that circumstance the engine would probably start, and be ok with the glow leads attached.

I suspect of pressure leak or a blockage somewhere.

John
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« Reply #29 on: April 07, 2011, 03:38:36 PM »

Thanks John,
I'll describe what I'm doing with the engine and anyone can give their opinion.

I was flying with 25% nitro, caster oil as lube sold by John Hook, it seems ok for these type of engines and I'd been using it earlier in my OS 15 powered dixie and it went fine. I had a bladder made from black tubing. With the bladder full (20cc)and the fuel line connected to the needle valve fully closed. I then held the model with the venturi pointing down and opened the needle valve until fuel was dripping down. At this point I tried it on the starter. I had a spark as I could hear the crackle as I engaged the clip and see the sparks, so the plug was not burnt out. The clip didn't fit as well on the plug in this engine and would fall off. I tried various needle valve settings and ground away on the starter but couldn't get the engine to fire. I gave up with the pressure as I'd sprayed about 100ml about and was getting fed up. I couldn't believe that some of that fuel wouldn't get into the engine and at least make it pop a bit. I took the bladder off and just tried squirting some fuel into the venturi, I got a couple of short bursts but it wouldn't pick up and run. It seemed to be going very slowly and almost wheezing. The reason I was going to try a new plug is the top of the OS plugs seem to hold the clip better. I wondered whether the clip was vibrating when against the starter and not giving the plug proper heating?

The engine itself seems to be a nice condition OS20fp with a nice amount of compression. I did try to run it out of the model a while back and it exhibited a similar lack of willingness to run. I had it jury rigged on a piece of wood with a hard tank to try to run on suction. Because of the set up it was a bit cack handed with short wires to the glow plug. As I was crouching and holding the piece of wood in a certain manner to get the glow clip to reach, I pushed it against the starter and it fired immediately and I flinched and the prop blade clipped the starter boss! most disturbing! It also fired the rubber insert somewhere never to be found.
Any Ideas what to try next?
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glidermaster
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« Reply #30 on: April 07, 2011, 04:44:15 PM »

Hmmm!
Fuel - sounds OK. Filling the bladder, etc etc - that sounds OK, too. Glow Leads/Clip - now this sounds a bit dodgy! (if a different plug makes the clip fit better, then changing does make sense). If your plug happened to be a Taylor, it's possible there isn't enough electrical juice for it - especially if the clip is a bit loose. The clip has to fit securely - if it falls off as soon as the engine fires, you're in for frustration at the very least.

The OS FP engines are usually fairly easy to start. Personally I never put plain bearing engines in a starter - I hand start. I don't recommend this unless one has PLENTY of experience, but when an engine is ready to start it has a certain feel that you don't get with a starter (obviously).

Your description of the crackling noise tells me there was fuel on the plug (good), so when you engaged it in the starter (you would have the fuel line pinched off at that stage), it should have fired right up. When it fires you let go of the fuel line, but stay ready to pinch it again if it goes rich. If you don't do this (pinching the fuel line) you just end up flooded.

John
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« Reply #31 on: April 07, 2011, 07:54:07 PM »

You need to be certain the battery leads aren't grounding out. Insulate, change clips, whatever it takes.

It doesn't sound like yo're even running out a prime. I would get the engine dry. Spin it without adding fuel. Give it four drops of prime, pull it through with a battery attached until it bumps. Then hit it. If it runs out the prime, that's a good start. Repeat, and be ready to open the fuel line when it fires.
You might be too rich to start and simply flooding it. Try setting the needle for 4 drops/second to begin.

Running on bladder pressure is simple enough once you're used to a few tricks. Most engines will start on a prime and then get fuel opened. Some like to go into the starter dry and have the fuel opened. This isn't a good idea on a bushed engine. I'll use a starter on a bushed engine but it doesn't stay in there long.

Here is a quirk that some guys cannot fathom. A lot of small engines -049 especially- will start and be running REAL slobbering rich. This is after it already been run and a needle setting is established. Some guys will lean out the needle on this rich running engine. Wrong procedure. As soon as it leans out it'll be way out adjustment and will probably quit before you can get the needle opened back up. Just pinch the fuel line until it leans out and then let go. You're back in business.
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« Reply #32 on: July 13, 2011, 04:05:43 PM »

small update,
At the weekend I took the heatwave fuselage with me to the Area event and in the afternoon tried to start it again.  With a new OS8 plug and a little more juice to the plug, I filled the balloon, got it dripping out of the venturi and tried it.  It started straight away and ran well.  The cut off works a treat!
So the Heatwave is back ready for trimming the next time out.
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« Reply #33 on: July 13, 2011, 04:33:15 PM »

Adam, sounds like you've got the engine issues resolved!! Can't wait to hear about the test flights!

Scott
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« Reply #34 on: July 13, 2011, 06:34:38 PM »

Adam,
Let the real fun begin!
Well done.

John
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« Reply #35 on: February 16, 2013, 04:25:59 PM »

The Heatwave has finally flown!
This has been a long drawn out saga...
When I moved a little over a year ago I looked at the wing of the Heatwave and the trailing edge had warped.  Before I could fly it I had to do some surgery on the wing, I stripped the centre section and I cut away the trailing edge and fitted in a new section of harder wood.  I was a bit scared of the whole bladder set up as it was another new thing on the largest model I had built up to now.  I swapped out the OS 20 and fitted a PAW 19 CT3.  With this engine I tried the model last year in about May.  The first flight it went up and to the left and looked like it was going to terminate itself.  Luckily the tailplane came off before it hit terra firma and it came down softly but the stab was broken.

Over the winter I built a new stabiliser as the old one had a tendency to warp after I'd repaired it. I took out the left thrust from the engine and added some more turn to the fin.  Finally today the weather was calm and went and tried it again at Epsom.  With a bit more rudder and a 1/64th less elevation it was going up in a nice stable spiral and turned into what looked like a good glide.  The engine wasn't fully leaned out so there is a bit more to come.  With the PAW its going to be quite safe, I think.

But I feel so happy that its finally flown and isn't looking at me reproachfully from the shelf in the garage anymore.
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« Reply #36 on: February 16, 2013, 07:32:26 PM »

Well done.  Good to hear.  Nice when you get them going. Smiley
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« Reply #37 on: February 17, 2013, 05:30:29 PM »

Good stuff Adam, it sounds like it is progressing well.

So you're now running a PAW 19 - did you put in a hard tank, or are you still on a bladder?
John
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