VoughtF4U

My Feedback: (1)

Got a quick question. Are guys not using gas engines strictly because of the weight? I am starting to look into what I want to build next fall/winter. After researching some specs on something like a Fantasy, I started wondering why I couldn't use a gas engine.

If I compare the wing area and weights of a Fantasy against something like my Sig Sukhoi I come up with the following.

Assuming 1100 sq. in. for the Fantasy, with a YS 1.40, I figure you come up with a finished weight of about 10 pounds. I figure the YS runs about 2 pounds, maybe a little more with the tuned pipe. Assuming all this I get a wing loading around 21 oz./sq. ft.

You can get a 40-50 cc gas motor now around 3 pounds. The DA 50cc is right at 3 pounds and the FPE 40cc is about 2.75 pounds. So add about a pound extra for the gas motor over the YS. This brings the total weight up around 11 pounds. Wing loading goes up to about 23 oz./sq. ft.

Compare this to my Sig Sukhoi, 1152 sq. in., 13.5 pounds, wing loading about 27 oz./sq. ft. The Sukhoi flies great at this wing loading and I have no complaints about it. It slows to a crawl and will accerlerate vertically no problem.

Will the performance of the Fantasy suffer from an extra pound of weight that much? What am I missing here?

bla bla

I just don't thick you have to go for so many cc's with that type of aeroplane. We've just started experimenting with an F3a aeroplane equiped with gass, a ZDZ40. Man more than enough power... I mean so much it was basically unusable.

Don't seen to think weight is an issue anymore..
noise is. We have to work out the pipes (re. mufflers) and the soft mounts... need a total new thinking here as the old Hyde and a nose ring approuch dosn't work any more... then its props... which effect under cart lenth...ahhhhh etc etc.
Weight isn't an issue.
As stated.. 50cc on an 11lb model? 40cc was total over kill... in a nice way....
Not at all nessessary unless your in love with 11 degrees of right thrust.

VoughtF4U

My Feedback: (1)

Yep, I didn't read through my post very well. The engine I was thinking about was one of the smaller 20cc, 30cc, or at the absolute most a 40cc.

cameron

Remember you have still got to add a header & pipe, as well as the ignition battery to the "3lB" you calculated for engine weight.
Then the C.G will also be a problem on a plane designed for glow.

The Fantasy is not going to make it under 11lb with a gasser, its too heavy, (based on what other people have said about its weight).

If you mean the Fantasy A.A machine, rather than the Eclipse, then yes wing loading is critical to the 3D performance.

I think gassers can be made to work, but with the gas engines currently available, they will not work in a design intended for glow power. (not without significant modification anyway)

As for the soft mounts, the nose ring should be the only problem, the basic pricple of the Hyde mount should still apply, shouldn't it?

There was an interesting article on gas engines for pattern, By Gerry Dale, in the May edition of RCModeler.

The cover has his gas powered smaragd., while his article details the construction of his own design, called the L'Essence 2, for gas power. He used the RCS 180, though at that weight, I don't see why you wouldn't choose the ZDZ40 re.


Does anyone know of any pipes available for gassers?
I see the K&S pipes on the DA site but $$$$$$$$$$, and I guess with 40cc in an 11lb plane, you don't really need a "tuned" pipe, only a light weight, noise suppressing pipe, without reducing rpm too much.

Roberto B.

Does anyone noticed this engine?:

http://www.modellexclusiv.de/SM_Motoren/SM30/sm30.html

Its weight is very promising.

I think that to make a soft mount is not a difficult task for it.

I don't know if his power would be enough.
To a request of mine, the answered:

"We fly SM30 with Meizlik 18/8 (8300 rpm) and 18/10 (7800-7900 rpm). The engine at the moment is used in F3A Giles and Extra300 with good results. We use tunde pipes from PeFa especially made for F3A models. The noise is at 78dB / 7000rpm (standard for F3A use) and 82dB at 8000rpm used at torque."

If this engine should work well, I think we've got the solution.

Roberto - Modelcompositi

www.modelcompositi.com

pizza

My Feedback: (24)

I am currently flying a 2m pattern plane scratch built by Dick Hanson for zdz40re. It weighs under 11lb and has ballistic performance using a 3w 20X8 prop and es designs gas carbon fiber tuned muffler prototype. Ed has tooling made for 3 different gas cf pipes but just got a new girlfriend with big jugs so retail production has been pushed back. check website for update.

manu2604

My Feedback: (2)

What about the 3W 24i? The Matt's use it in their 3W Xtra-fun. The plane is 1.9 m wingspan and 1.99 lenght(like the pattern planes), it weights 4.8-5.0 kg wich is ok for pattern rules. This model is designed for 3D but maybe it is possible to change the design for pattern flight, use the same engine and maintain the same weight. Note that they use it for 3D, so it should have plenty of power. This is the link:

http://www.matt-rc.li/englisch/index.htm

Just an idea,

Manu2604

pizza

My Feedback: (24)

That engine might be ok at sea level but 5000"???

cameron

Roberto what does the stated weight of 1145g of the SM30 include? The engine does look promising, and 78db, that is quiet!!!!!


pizza, is that the Yellow , 1280 sq inch wing Plane Dick Hansen built?

What rpm does the ZDZ turn on that prop? db level?

Does es designs have a web site? Is the pipe "tuned" or just noise suppressing? what does the pipe weigh?


Also where can I see the PeFa pipes Roberto mentioned?

Thankyou ,
Cameron McDonald

cameron

Roberto, you know alot about soft mounting engines, how would you go about it?

Roberto B.

Hi Cameron,

That weight is with the ignition module included.

About the soft mount, I would keep the same principle of the Hyde mounts, without the nose ring.
Just make the rear rubbered plate wider, with an incorporated carbon fiber flange suited for such engine.
With my soft mount design it's easy to make the carburettor fit through it.

About the pefa muffler, this is their web site:
http://www.pefa-modelltechnik.de/
but it is not updated since 2001...

bla bla

This is interesting stuff indeed.... but we must find away of soft/hyde mounting with a nose ring.
It's just not good enough without the front end locked down. 1/4 a degree movement is enough to blow the trimming.

cameron

Thanks Roberto,
That is quite a good engine weight, only about 200 grams heavier than the os 160.

Thanks for the link, gee I wish I could read German!!!!!

As for the soft mount, wouldn't the engine move to much without a nose ring?

Roberto B.

Of course, the engine wouldn't be as stiff as with the nose ring (even if Chip Hyde is able to muont his 4 cylinders DA200 on his TOC winning bipe without nose ring... ).

I think that some real testing should be undergone.

If a nose ring should be needed anyway, the only solution is to make a new pick-up sensor case, mounted (suspended) on a different location (the two front cylider bolts?).
This mounting should be very stiff because the gap between the sensor and the magnet is critical.

It wouldn't be easy to make, but not impossible.

To put the engine in the model can be a little pain, because you have to pull the propeller attachment away (I don't remember his correct name in english..), put the engine into his place, MOUNT the pick-up on the correct position, re-install the prop attachment.

cameron

Yes I see what you mean bla bla, the ignition sensor gets in the way, only leaving 4 tapered splines of crank-case to attach the nose ring to.

Perhaps the ignition sensor could be removed and mounted off the nose ring support?
But I guess this would affect the engine running, as the engine vibrates and twists.

The nose of the SM30 seems very short, but the ZDZ is longer.

The only round section is again utilised by the ignition sensor, but perhaps an aluminium adaptor could be made to slip over the tapered "splines" and attach by a grub screw to each spline.
The outside of this bracket could be made round, to mount the nose ring around.

Maybe you can see what I am thinking in the attached image.
Imagine the bracket mounted on the splines, slightly behind the round section where the sensor is mounted.

I cant get the image to attach, it must be too big.
here is the link- http://zdz-modelmotor.cz/zdz/pics/galerie/single/5.jpg

Sorry Roberto, I didn't mean to repeat anything you said, you type faster than I!!!!!!!!

pizza

My Feedback: (24)

Hi Cameron, my plane is identical to the one Dick Hanson had at the TOC, except mine has a Dalotel canopy and cowl.

www.escomposites.com is eds website, he still needs to update it with new gas pipes which are larger than pattern pipes available now. Ed has the numbers, all I remember is the cf pipe is 4db quieter, 200 rpm more, and 25% weight of ks system I was using.

I use rubber well nuts to soft mount the engine, they reduce the shake a little bit but gets rid of that terrible guitar noise I was getting just above idle. the rubber well nuts cost $1.75 for a set and weigh less than a steel nut with lock washer.

LeeDavis

I flew in the same district as Jerry Dale (he just moved to Florida - will miss him) and the 30cc RCS was a touch marginal in terms of vertical performance. He had it on a tuned pipe. Unless there's more power to be had from a 30cc engine I believe we need something in the 35cc-40cc range.

The lighter weight 50cc engine that Desert Aircraft is working on is more engine than we need. I've contact another gas engine manufacturer to try to drum up interest in producing a light engine for pattern. They're listening but the problem is that they can't keep up with orders for what they've already got.

If you have industry contacts, use them. I'm pursuing the reasoning that what's good for Pattern is also good for the huge market of mid-sized ARF's, like the Hanger 9 CAP and others, that have wing loading issues with current gas engine weights.

cameron

Are DA making a lighter DA50?

Thanks pizza, holly cow those pipes are alot of $$$$$$$$, but by the sounds of it, worth it.

I have heard that BME were doing something about a light weight 30 cc engine, I can't remember the claimed weight, but it was light.

By the sounds of it, maybe not enough engine though?

I agree about the arf common ground power requirements with pattern. With such potential, this market will surely be filled by one of the engine manufacturers soon?

pizza

My Feedback: (24)

I am selling my 2m dick hanson gas pattern plane on this list with pictures. it weighs under 11lb and has soft engine mount. go to classified airplanes ready to fly page 2. It might also be IMAC legal? kinda looks like a stretched dalotel.

AdrianM

I am certain ALL of the gas engine companies are working on small light gas engines. They all want to get into the F3A planes and 25% and smaller glow models. Right now glow engines fly these size models better.

Bob Pastorello

My Feedback: (198)

I bought Dick's "Petrel", and have about 3 hours on it with his ZDZ 40. Motor is hard mounted, prop is Bambula 20 x 10, muffler is his Vtech canister...it was pretty noisy until I soft mounted the entire exhaust system. Between running the Bambula (very quiet compared to others) and the soft mounts, airborne, this airplane is no louder than MANY, MANY current pattern designs.
Reason - in flight throttle settings are nearly ALWAYS less than 1/2 power that is available with this motor.
As someone else already said, it's almost TOO much power, but the throttle curve function has really helped. It's a pretty remarkable airplane.....see my website, click on "Petrel" to read about it and see photos.

bla bla

I've just read your web pages and yes, as we'd found out the power was simple off the scale.
With the trend firmly towards wide bodies and now biplanes gas is offering performance a Dindo simply can't compare with.
If only we can work out a softmount/nose ring/muffler pipe set up!!!!!

Bob Pastorello

My Feedback: (198)

Even though weight is about the same as the 40, this RCS motor (looks a LOT like a Moki), at least has in internal ignition sensor which means where the nose ring goes is uncluttered....anyone heard about, or run one of these???
RCS 1.80 Gasser It's available as a rear-exhaust....and the radial standoffs make it a long-nose...

pizza

My Feedback: (24)

Hey Bob P the next step is to soft mount the engine with wellnuts - Lowes sells a wellnut that has the exact thread size for zdz 40 - simply open up the holes already in firewall to accept the wellnuts - this isolates the engine from airplane with rubber = vibration is a little less but you get rid of that horrible guitar noise just above idle, creates a soft sound throughout power curve. the wellnuts cost $1.75 for a set. If you had a wide body pattern plane with large firewall you could attach an oversized carbon fiber plate to back of engine then attach the wellnuts to the outer corners of plate through firewall near where it meets the airplane - this setup would rival a hydemount without the weight and too much rocking for the cost of plate and wellnuts - maybe $18 someone said if its not tried its unknown?

can773

My Feedback: (1)

I am sure that this setup is quiet in the air, unfortunately, the noise testing is done on the ground at full throttle.

In that enviornment how does the noise compare?? Current FAI limits are 94 @3m on asphalt and 92 @3m on grass, AMA limits are 2 dB higher.