Author Topic: AP Wasp props? (Read 3869 times)

Andrew Tinsley · « **on:** March 20, 2012, 07:51:16 AM »

Hello All,
Strange request this! I need to keep the noise down on an AP Wasp powered stunter. I can fly it close to my home if I can keep the wasp like noise in check. I don't have much idea of what the power curve is, but if anything, I have too much power available, so I can afford to lose some.
Easiest thing is to go out and try a selection of props, but apart from some Cox props, the cupboard is a bit bare. So any suggestions of what I might try? Maybe a Kavan or APC 6x4 inch or even a touch bigger? If these are no good I can use them on small diesels.
Getting small props locally is difficult, so I would like to get it about right first time!

Regards,

Andrew.

P.S. I am using an APC 5.5 x 3.5 right now.

John Rist · « **Reply #1 on:** March 20, 2012, 08:24:37 AM »

Norvel 049 comes with a muffler. not cheep

http://www.ebay.com/itm/Northern-Velocity-Norvel-AME-049-049-C-L-High-Performance-Engine-/160752696042?pt=Radio_Control_Parts_Accessories&hash=item256d9b7aea

kenneth cook · « **Reply #2 on:** March 20, 2012, 09:29:59 AM »

Hello Andrew, my experience with this engine was for combat use only. I would think in the APC, a 5.5 x 2, 5.5 x 2.5, 6 x 2, 5.7 x 3 . Those props are lighter on pitch aside from the last one and would possibly solve your too much power. They do however work very effectively on my Norvel's with the same porting. You don't have a muffler with this engine? I don't know what size plane your flying, but I did find the Cox black rubber ducky to work fairly well (non safety tip). The lighter pitch props though are going to be noisier though. When you state too much power, are you saying the plane is flying too fast? A 6x4 is really going to move out due to that engine having the ability to swing it. I would think if your trying to bleed off speed but still have the drive, the 5.5 x 2.5 would be the solution. Ken

Andrew Tinsley · « **Reply #3 on:** March 20, 2012, 10:55:41 AM »

Hello Ken and John,
I am using the standard muffler with the Wasp. I must say the Norvel 0.061 is just as noisy with muffler as the wasp, at least to my restricted hearing!
I have plenty of speed and can afford to lose quite a lot. I was looking to get down the left hand side of the power curve and reduce the prop speed. I suppose that it is asking a lot of an engine designed to rev. I would be better off with one of my diesels if truth were told.
I have got to like the Wasp and Norvels, I am just being lazy, if I travel a mile or two I can get to a less noise sensitve area, so I suppose that is what I should do! I have one of the suggested cox props and will try that together with a Kavan 6 x 4 yellow prop which I have just found. I will report back and see what the neighbours think!

Thanks for the suggestions,

Andrew.

Larry Renger · « **Reply #4 on:** March 21, 2012, 08:56:36 AM »

Has anyone dieselized an AP Wasp? I just bought the MECOA head and plan to try it out soon. That could let you run larger, slower props and diesels are inherantly quieter, too.

Andrew Tinsley · « **Reply #5 on:** March 21, 2012, 01:08:00 PM »

Hi Larry,
Now why didn't I think of that? I have been so interested in dieselising cheap Coxes, that the obvious answer to my Wasp noise problem is staring me in the face! I really am beginning to wonder if I am safe to be let lose on the forum! Thanks for the idea, I will report back as soon as I get a mecoa or Norvel diesel head. I don't think the Davis head will work on a Wasp, methinks too much heat will be generated for the fluorocarbon disc to stand up to it.

Thanks!

Andrew.

Larry Renger · « **Reply #6 on:** March 22, 2012, 09:50:32 AM »

Always glad to be of service!

dankar · « **Reply #7 on:** April 02, 2012, 12:19:24 PM »

Go electric?

Andrew Tinsley · « **Reply #8 on:** April 03, 2012, 04:07:12 AM »

Hi Dan,
It is a good thought except that I don't do electric! If it doesn't have an IC engine or CO2 motor up front then the interest in flying just evaporates for me. The day that electric flight takes over and the last of myIC engines is worn out is the day I stop flying.

Regards,

Andrew.

don Burke · « **Reply #9 on:** April 03, 2012, 11:01:52 AM »

ditto!

GGeezer · « **Reply #10 on:** April 04, 2012, 12:52:17 AM »

And the real alpha-male he-men fly diesel IC

.

Andrew Tinsley · « **Reply #11 on:** April 04, 2012, 03:27:06 AM »

Hello !
I must emphasise that although I do fly diesel, I am far from being an alpha male!!!!!! Really, who would want to look like Vladimir Putin? Flying diesel is a genetic thing. All Brits of a certain age were weaned on diesel fuel, so flying diesel is natural for them. We look a bit askance at our US cousins flying those odd looking glow engines, without a Tommy Bar (meaning the compression adjuster).
I must admit that most of us do smell rather strangely!

Regards,

Andrew.

Larry Renger · « **Reply #12 on:** April 04, 2012, 04:08:14 PM »

Back to the topic of this thread!

Have you tried a diesel head on the Wasp yet?

George · « **Reply #13 on:** April 04, 2012, 06:44:45 PM »

Quote from: Andrew Tinsley on April 03, 2012, 04:07:12 AM

Hi Dan,
It is a good thought except that I don't do electric! If it doesn't have an IC engine or CO2 motor up front then the interest in flying just evaporates for me. The day that electric flight takes over and the last of myIC engines is worn out is the day I stop flying.

Regards,
Andrew.

Some of us believe 'lectric belongs in food Processors and Coffee Makers!

George

Andrew Tinsley · « **Reply #14 on:** April 05, 2012, 03:02:20 AM »

Hello Larry,
The only head I have available at the moment is a Davis head, had enough problems with that on some Cox reedies, it works, but if the mixture is a bit lean then bang goes the sealing disc. The Mecoa head is still to be ordered because they are in the middle of a move and will not be able to action an order at this time. So it is all down to the Norvel head, which I should have soon!

Regards,

Andrew.

Larry Renger · « **Reply #15 on:** April 05, 2012, 08:28:03 AM »

There are reports of people making replacement disks out of old soda cans. I haven't tried it, but what harm would there be in trying?

Andrew Tinsley · « **Reply #16 on:** April 05, 2012, 08:57:15 AM »

Hello Larry,
I am game to try anything! The fluorocarbon discs are somewhat delicate. They work on the Cox engines as long as you don't lean them out too much. The Norvel or Mecoa heads are to be preferred I would wager, but they are probably one to two weeks away. So soda cans it is. Should be able to cobble up something and report back tomorrow.

Regards,

Andrew.

Bill Adair · « **Reply #17 on:** April 05, 2012, 04:42:41 PM »

Andrew,

I seem to recall that the soda can material was used to replace the aluminum flame shield, and not the Teflon disk?

Bill

Larry Renger · « **Reply #18 on:** April 05, 2012, 11:10:55 PM »

What flame shield? The Davis head has the housing, a compression screw with spring, a contra piston and the teflon disks.

The thin aluminum is used to replace the teflon. Apparently it is soft enough to function as a variable compression seal. I wonder if aluminum foil would work even better? Maybe two or three layers for strength, but with flexibility.

Bill Adair · « **Reply #19 on:** April 06, 2012, 01:34:06 AM »

Darned if I know.

I was told there was a small aluminum disk attached to the Teflon membrane that usually failed, and that soda can material could be used to replace that part.

Perhaps they confused Teflon, with aluminum?

Andrew Tinsley · « **Reply #20 on:** April 06, 2012, 02:28:13 AM »

Hello Bill,
The Norvel head has not shown up yet unfortunately. So I shall have a go with the Davis head. The seal for the contapiston on these heads is provided by a white Fluourocarbon(?) disc. It isn't too smart, as the material is very close to its destruct temperature and usually fails after a few runs. In fact everytime if you lean out the mixture too much.
It is asunny but cold day here so I shall be disc cutting and test running later. I used to have some very thick aluminium foil that I used in vacuumm coaters to shield things that didn't want to get coated. It was halfway between foil and thin sheet aluminium. If I can find some of that then it would be perfect!
Results will be reported soon.

Regards,

Andrew.

Larry Renger · « **Reply #21 on:** April 06, 2012, 08:53:33 AM »

The Teflon disk was designed to fail to protect the engine. Unfortunately, in my opinion, it is too critical and doesn't give you time to correct a mis-adjustment. Bob does sell several thicknesses, the thicker ones can take more heat.

Andrew Tinsley · « **Reply #22 on:** April 06, 2012, 11:59:05 AM »

Hello All,
Right, I have done some test running with the Davis Head. I have used one "can" disc and one from my small stock of thick aluminium foil. They both work, but not all that well. There is a rather vague feeling about the compression adjustment and after a few runs, both discs cracked and the compression seal was lost. Maybe a bit more experimenting is required.
Results, these were taken with a mild brew of diesel fuel D1000, if that means anything. It is the stuff I normally use in my sideport engines like Mills etc. Small props (5 and 6 inch diameter) inflicted some damage to my finger (ouch!). The set up I was using was a bit prone to flooding, so that needs sorting. The engine was well run in and a "Jan" venturi was fitted. 7" inch props were much more civilised and they are the diameter I would use on a 1 cc diesel anyway. First up was an APC 7x3 and I got slightly over 16,000 rpm on this. The only other prop I tried was a Kavan 7x4 and a good steady 12,500 was seen with this. Results were perhaps a little less than expected but considering the mild fuel and perhaps not the best possible venturi diameter, I thought the figures were quite good. I am sure with an optimised set up and hotter fuel, these results could be improved upon. Hot restarting wasn't brilliant, but perhaps not unexpected. I retired with finger damage and now await a Norvel head.
I have no idea how the Wasp will stand up to being diselised! Before you all rush out (!) and try it, remember that if your Wasp breaks, don't blame me!
Oh and I almost forgot to say that the noise level was pleasantly low with the standard silencer. After all, that was the original reason for the post!

Regards,

Andrew.

minnesotamodeler · « **Reply #23 on:** April 06, 2012, 04:49:54 PM »

You know, you can work a short length of large fuel line onto the outlet of the muffler (Norvel type) that will quiet it down to a purr...cuts power way down too, but could be adjusted to optimum compromise by trimming the length of fuel line.

Mike Keville · « **Reply #24 on:** April 06, 2012, 04:53:56 PM »

Quote from: George Bain on April 04, 2012, 06:44:45 PM

Some of us believe 'lectric belongs in food Processors and Coffee Makers!
George

AMEN !!!

Andrew Tinsley · « **Reply #25 on:** April 07, 2012, 06:57:07 AM »

Hello All,
A Norvel head turned up in the post. A Big Thank You to Bill Adair for this! It is one of the early heads that need a little machining to make them seal adequately. I think Bill gave in when he ruined a Norvel using it. A great shame that happened, Bill hadn't run the Norvel adequately and that caused the problem. So make sure you have a WELL RUN IN engine before you try a diesel head.
I need to do a little machining on the head and that will have to be done on a friends lathe as mine is still in pieces. I will let you know what happens when it is ready to fire up.
A query here, most diesels run on a smaller venturi than the corresponding glow engine. So maybe I should put the R/C carb back on the engine and try reducing the venturi cross sectional area? To be honest, I am not really too bothered about getting top revs out of the Diesel Wasp, 16,000 odd revs on a 7x3 APC is way good enough for what I need........and it is quiet too, maybe even quieter with a length of tube on the silencer!
Now to see if a dieselised Wasp stays together. I can afford to risk one Wasp, I don't have as many as Larry, but I have at least another half a dozen. Like the FP20 I have enough to last me out!

Regards,

Andrew.

Larry Renger · « **Reply #26 on:** April 07, 2012, 04:34:51 PM »

I purchased "Dr. Diesel's Diary" from Eric Clutton. I learned a lot from it.

One interesting thing is he says you can run diesel fuel in just about any glow engine with NO MODIFICATION! Just get the plug real hot, and it can be started. Once up to temperature, it will continue to run without the heater. He says the run will be pretty gutless due to lower compression. I would think it easy to just turn down the sealing surface of a Merlin glo-button little by little until an acceptable compression ratio is found.

Andrew Tinsley · « **Reply #27 on:** April 08, 2012, 01:05:41 AM »

Larry,
You may be able to run diesel fuel in a glow engine, but you will not get very good results, even if you raise the compression ratio. Fixed compression diesels went out with the ark and for very good reason. Starting CR is usually different from running CR and the optimum running CR differs with ambient temperature and fuel mix. What you are suggesting is not a very practical idea.
The fuel bypass and intake can be very different on diesel and glow engines. For out and out racing there is little or no difference. For the famed constant speed run of a big stunt diesel , like PAW 's 40 to 60 size engines, they deliberately restrict the bypass size and use what to me looks like a lot smaller venturi.
I will leave turning down Merlin glow buttons to someone else, it is not a way I would want to go!

Regards,

Andrew.

Larry Renger · « **Reply #28 on:** April 09, 2012, 11:09:43 AM »

I have a batch of PAW engines: 2 55s, 2 .049s, 2 .061s, and one each bb .09 and .15, plus the 35. Also a few Davis mod OS .10 and .15 engines. Not likely to mess with the fixed head any time soon, myself. But it is an interesting thing. I also have both the Davis and MECOA heads for Cox compatible engines.

Andrew Tinsley · « **Reply #29 on:** April 10, 2012, 03:13:01 AM »

Hello Larry,
I am obviously preaching to the converted! Running as the Wasp a fixed head diesel, would be fun, but I don't have the time or inclination. I have enough problems as it is! The story about Davis using the Teflon seal as a safety feauture, is a good one, but I think it is a bit of an excuse for poor design philosophy. Out of the three heads one can buy, the Norvel is by far the best (assuming you don't have one with the early ones with sealing problems. This is followed by the Mecoa head with o ring seal, and at the bottom of the list would be the Davis head as far as I am concerned.
I should have the Norvel head machined up and ready to go by the end of the week, so I will report back.
As long as the Wasp is beefy enough to take diesel conversion, it should be a cheap and satisfactory little diesel with performance as good as or even a little better than the corresponding PAW.
I am hoping to get a decent Wasp back from the suppliers, in exchange for the one with the very loose crank. not sure how this got through QA, it is a shocker and very obvious!

Regards,

Andrew.