ZDZ 224

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ZDZ 224

Postby Freestyle dude on Sun Feb 03, 2019 4:02 pm

I have a ZDZ 224 turning a Falcon 30X14. Approximately what rpm should a 224 turn this propeller?
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Re: ZDZ 224

Postby Billy Bunter on Sun Feb 03, 2019 8:42 pm

Hey Angus,

I was hoping to get out today with my Yak55 that has the MVVS 190 in it and the Aukhoi with the M220 to take rpm readings with a Mej 32x12 and a 32x12 EVO to get some readings, altering your posts on FG. But, I had to work today on a crisis job for a client.

I’ll try and get out this coming weekend if the weather allows to get some readings for you. Obviously I’m not doing this with a ZDZ224, but they are engines in the same class, so they should give you an idea. I think the 32x12 EVO is going to be very close on load to the 34x14. I’d use a 34x14, but I don’t have one in my collection of props.

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Re: ZDZ 224

Postby Billy Bunter on Mon Feb 04, 2019 1:07 pm

I just checked on some data that Trevor Brum generated for the M220 that I remembered I’d archived. Here you go

* Mej 30x13EvoL: 6660 - 6720rpm
* Mej 31x12EvoL: 6580 - 6610rpm
* Mej 32x12: 6240rpm
* Menz34x12: 5450rpm
* Beila 33x12: 5550rpm
* Mej 28.5x12-3B: 6830rpm

It’s from a different engine, but even so I’d expect somewhat similar performance as they are about the same displacement.

Hope this helps.

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Re: ZDZ 224

Postby Freestyle dude on Mon Feb 04, 2019 5:46 pm

Thanks Stu, good info. I'm currently getting 5650rpm on a Falcon 30x14.
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Re: ZDZ 224

Postby Ally Young on Mon Feb 04, 2019 7:01 pm

Hi Angus,

Would you not be looking to prop it for around 5900 to 6100 to give a good compromise between pull / ability to keep going in the power hungry bits of your Unlimited IMAC sequences without bogging down and not ripping too much and being erratic if it is revving too high and under pitched? 14" pitch seems a lot, you will need some power to power a 30x14 up to around 6000 even with a powerful 4 pot. But, I don't know how powerful your motor is, it must be some animal to even turn that at 5600 on the ground. Would it be worth going to a 30.5 X 13 or a 31x 13 to try that?( if you can get such a zize) I know from your F3A heritage how much you guys like big pitch.....but what's the gain? is it more constant speed through the sequence? I know a DLE 170 will hit about 5600-5700 on a Mejzlik 30x13 Evo LF on cans but with way less power than you have.
I am looking forward to seeing your ZDZ in action in August....... :D
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Re: ZDZ 224

Postby Billy Bunter on Mon Feb 04, 2019 7:47 pm

I just realised you were asking about a 30x14 NOT a 34x14.... doh!

So, can’t see the need for my testing, I think Trevor’s numbers are enough.

Ally, respectfully, I think you are off in your assessment. These quads don’t bog down like twins do. I think that Angus’ engine is about 1,000rpm off where it needs to be. Something is wrong. My Mintor 220 can rip a 32x12 going vertical from a stop, this 224 should be near that performance.

Angus, what exhaust set up are you using? If it’s cans or pipes, what are they and what is the header length.

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Re: ZDZ 224

Postby Freestyle dude on Mon Feb 04, 2019 10:15 pm

Thanks guys. Yes, I do believe the engine is well short on power and have voiced my concerns to Michal, who predictably hasn't replied. I will hopefully get out again this weekend and run it some more. It basically runs fine but lacks top end power. By comparison my DA150 turns the same prop at 5700rpm. This quad should be around the 6200 - 6400 mark, so yes, not far off 1000rpm short of where it should be. Exhaust is JMB 2 into 1 in cowl silencers which have basically no restriction. I've been experimenting with designing my own silencer baffles and it actually sounds quite good now and I've got it to within 100rpm of the standard exhaust. The advantage being ultra lightweight and ultra simple. However, I may well end up fitting a proper canister set up. This Brietling is pretty stripped out. Final weight is 19.45kg with a 5kg engine so I was really pleased with that. If I could get the power out the ZDZ this aeroplane would be an absolute weapon. However, I suspect I'll be returning the engine to ZDZ and the chances of a quick turn around are nil unfortunately.
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Re: ZDZ 224

Postby Billy Bunter on Mon Feb 04, 2019 10:35 pm

Evening Angus,

I think the issue is your exhaust system and if you return th engine to ZDZ you may be in for a very long wait before you get it back!

Overall I’d try changing the exhausts first. Apparently the cans on my Mintor’s are (somewhat) tuned and I’m sure they are responsible for a large amount of the power the engine develops. Albeit header length is also a factor. I do have a spare set here I could loan you to try if that helps. You’d need to organise some headers.

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Re: ZDZ 224

Postby Ally Young on Mon Feb 04, 2019 11:18 pm

Hi guys,

I know that Dan Gallo had a dip of 500 rpm on the engine in his Dalton ( think it is a ZDZ 180 twin?) ..it was down to his cans being full of soot. A good clean out of the cans and rpm back up by 5-600. It shows how critical the breathing is...Have you clocked it with the exhausts off to check if that is where the difference to what you expect is coming from ......not near anyone!
I hear what Stuart is saying about big 4 cylinder engines not bogging down as much as twins , I've no direct experience of running one myself although I've seen plenty in action, so from what you are saying it should be able to cope with the 14" pitch prop, but will that not make it pull on even at tick over for landing?
Angus, I assume you've gone through all the obvious stuff like plugs, plug gap, ignition battery, reeds, timing, fresh petrol etc?
I am amazed that you recon to get 6200-6400 on a 30 X 14 prop! That is a lot of power. ( How would it go on a 29x12 3 blade or would it rip that too much? )

Angus......you know the guy who knows ZDZs........ ;)
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Re: ZDZ 224

Postby Freestyle dude on Tue Feb 05, 2019 12:15 am

The JMB exhausts are essentially open exhausts. Yes some cans produce a mild tuning effect but even if I fitted pipes and got an extra 500rpm I'd still be off what I think I should be getting. Priced a full JMB exhaust system and it was €260 so not too bad really. Michal knows what exhaust system I'm using but hasn't replied yet. I will also ask Milan Brecka about his 2 into 1 exhausts vs proper cans. Actually re the carbon build up in cans, that was another reason for trying these 2 into 1s as there are no baffles to block up. This 330 was essentially bought as a hybrid IMAC/freestyle/practice aeroplane leaving the Swiss for the high end stuff. Hopefully that will still be the case but I do need to sort the engine power issues.

Re 14" pitch on landing. Not an issue Ally as I have a low tick over set for landing and just side slip it if need be. The advantages with the higher pitch props for IMAC far outweigh any minor landing issues, IMO. Three blade props, don't use them as they reduce outright performance and a blade always seems to be in the way when storing and transporting. Two blade props are absolutely fine if you manage the throttle properly.

Thanks for the kind offer of the loan of the cans Stuart. I have a set of MTW TD 110 cans on my 260 I can try so it would just be a matter of buying headers so I may well do that depending on what Michal and Milan say.

Plugs are OK, ignition is run through the rxes and rx batteries, petrol is new. Reeds and timing I haven't checked admittedly but starting is easy so I imagine the reeds are OK. Would need to check timing next time the cowl is off.
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