PlaneKrazee

My Feedback: (14)

The only gas engine that fits the bill is the SM30 from Germany. It will set you back over $550.00 with muffler and whatever else you need but it is the lightest, most powerful gas engine in it's class. Rear intake and exhaust and you need to make a plate to mount it to the firewall. No distributor in the US and if Morris get's it it might cost even more.

MalteS

In fact the SM30 is very interesting, however what I read in the german forums are good and bad opinions varing from "great engine loving it" over "difficult to set up" to "crap"
Mark180 (should be Moki in the US) could be also an alternative.

RysiuM

My Feedback: (1)

It is a work horse. However at 40 oz (2.5 lb) with ignition it is heavier than RCS 1.4 (44 oz including ignition, battery, switch and muffler). I know, SM30 i bigger and has more power. But it looks like for that plane if any gas motor will fit it is only RCS 1.4.

RC Showcase indicates to use NiCd for ignition. However I used LiPo with voltage regulator - it's lighter and easier to maintain. So being very carefull I might save ounce or two on the engine outfit too. I hope.

Anyone knows the lighter power system (I mean engine outfit plus fuel or maybe electric setup ) that will deliver around 15lb thrust?

RysiuM

PlaneKrazee

My Feedback: (14)

Sounds like you should buy the RCS140 and tell us how it goes.

3D Joy

The RCS 140 does not have 15 lbs of thrust... I have flown this engine in a 13.5 lbs aircraft and it would BARELY hold a hover or torque roll and that while going slightly backwards [X(]!! This engine has a hard time spinning an APC 17x6 [:-].

This engine is good for cubs or REALLY lightweight planes (no ARFs) or really optimistic guys .

RysiuM

My Feedback: (1)

Does it mean that on the [link=http://www.rcshowcase.com/html/engines/rcs140.html]RCSHOWCASE[/link] they write a BS?
RysiuM

3D Joy

The thrust readings on RCS website are extrapoled from ThrustHP, which is VERY optimistic.

RysiuM

My Feedback: (1)

RCS is on backorder. I decided to go with MVVS 1.6. It is 3cc bigger, only 2 oz heavier (bare engine) but much lighter if I use backplate mounting instead of the rail type. I would probably get very nice performance with tuned pipe (available) but it is to heavy for me. I will go with BCS inverted.

RysiuM

DT56

My Feedback: (18)

How about a diesel conversion of an OS 160?

Rcpilot

My Feedback: (78)

You're beating your head against the wall here bud.

You got a 73" wing with 800 sq. in.

The best performance is going to be a 2-stroke glow engine. Someone already mentioned a Moki 1.80 w/cline regulator. I'd go bigger--maybe the Moki 2.10 or the MDS 2.18 and definetely run a regulator with tank on the CG.

General rule of thumb is 1000 sq. in. or MORE for a gasser.

Your plane is never going to 3D well with a gasser on the nose. By the time you get a big enough engine to develope the power you need for 3D--the plane will be so overloaded it'll fly like sh*t.

For good 3D--you want to be hovering at 1/2 throttle. That leaves room for mistakes and gives you recovery power. Point the nose up and hammer the throttle.

All the thrust numbers given earlier don't mean squat. Because, those are all FULL THROTTLE numbers. You need to make 10--12 pounds of thrust at 1/2 throttle or thereabouts. Remember--you gots a 10LB airplane here--so to hover it at 1/2 throttle--you need an engine capable of making 10--12LBs thrust at that RPM.

I've been there. I've tried it. It don't work.

If you want a 3D plane with a gasser up front--then go to an 80" wing with 1200+ sq. in. and slap a 50cc or a 60cc engine on the firewall. Turn a 22-10 or a 24-8 prop at 7200RPM and have a blast.

Otherwise--stick with 2-stroke glow on your 800sq. in. wing.

Antique

My Feedback: (4)

Maybe yes, maybe no...The G26 DOES have 17+ lbs thrust, and desertpig has an Ultra Stik Lite that weighs 9 lbs 3 oz powered by an unconverted G26...It would be 9 lbs or less with a converted G26....You can check out his thread on the Giant RC Aircraft forum...
Takes off in 5 feet, hovers at 1/2 throttle....
The chart says 25 lbs thrust..
My thrust numbers have been verified by a scale on the tail wheel by myself and some of [my customers....Maybe one of them could check at what rpm the 10 lbs occurs....The 17+ is at 9000....

RysiuM

My Feedback: (1)

I just can't agree
3D is not the power to hover at half throttle. It is a compination of weight for light wingloading and power to fly on the propwash.

There is no really perfect motor for 10 lb 800sq in. Whatever engine you put it will be either underpowered or overweighted. That why it is easier to do it with bigger wing - more 3-5lb motors to choose.

Moki 1.8 is 41oz alone. Add muffler, mount and fuel and it will be easy 4 pounds or more. Reading performance database it does not put unusuall power - the same rpm on 18x8 I can get from MVVS 1.6 with tuned pipe.
Moki 2.1 is 5 oz heavier. Add muffler, mount and fuel - it will be pig hanging on the prop.

I Just weighted the MVVS 1.6 that came yesterday (I ordered it Friday from http://www.justengines.unseen.org/ and it came Tuesday to California) - Royal Mail with JustEngines service rules):

Motor with prop nut and washers with installed carb and plug weights 32.2oz
Ignition module with all wires - 5 oz
BCS inverted muffler 5 oz
LiPo battery plus voltage regulator - 2.5oz

Now I'm waiting for MVVS radial mount that weights less than 2 oz. Add 10 oz fuel plus 2 oz tank and I have gas setup less than 60 oz
For Moki 1.8 It will be 41oz motor, 8 oz mount, 3oz tank and at least 20 oz fuel - 72 oz.

See, what I mean?

RysiuM

PlaneKrazee

My Feedback: (14)

That Moki can spin a 1" larger prop at the same or greater rpm than the MVVS 160 on a regular muffler. Please keep us posted on your progress and let us know how you make out.

As a matter of fact an Enya R155 at 33oz burning 10% nitro will spin the same size prop as the MVVS 160 and will weigh less overall. You would get very good fuel consumption also as the Enya does not guzzle fuel. I fly for 10-12 minutes doing aerobatics in my 13# GP Chipmunk and have several oz. of fuel left in the 20 oz. Tettra tank. I run a APC 17X6 and get 9000 peaked.

Rcpilot

My Feedback: (78)

You said that you have a 10LB airframe. And it has 800sq. in. of wing.

I don't understand the statement about 3D power and 1/2 throttle hovering.

If you want to do 3D aerobatics--then you need enough power to hang that airframe on the prop. If you don't have enough power to hover--then you can't do 3D. PERIOD.

My statement about hovering at 1/2 throttle was more intended towards safety. If your gonna do 3D--then you need enough power to hover at LESS than MAX throttle.

If you put an engine on this airframe and it takes full throttle to hover--then you got no vertical acceleration from a hover. If your hovering at full throttle and you get in trouble--well--then your in trouble.

In order to do 3D aerobatics- you need enough engine to hover it comfortably at LESS than full throttle---that way you got power to pull the friggin' thing out and point it up when you need too. If you can't accelerate vertically (and I mean with authority--RIGHT NOW!!)--from a hovering position---then you should not be hovering. Anything less is asking for a bad accident.

Your not going to find ANY gasser that will put out the same power as a comparitively sized glow engine. Gassers are heavier---any way you slice it.

Gas does not deliver the same output/BTU as glow engines do.

A glow engine will always out-perform a gasser. Pound for pound--cube for cube--a glow engine always wins----hands down. I don't care what the manufacturers of the gasserrs say---they simply will NOT turn the same prop as a glow counterpart. Everyone will tell you that--because it's true.

To turn enough prop to hover your airframe---you will have to get a gasser thats WAY too heavy. It then increases your wingloading to the point that it's no good for 3D.

I don't know how else to say it. Your airframe doesn't have enough sq. in. to accomadate a gas engine and perform to your specifications. You can slap a big 'ole gasser up front and hover that sucker till the cows come home---but all the other flight characteristics will suck--because it's overloaded.

Good luck with whatever you chose--and please don't take this as an attack. I'm just telling you that in my experience--good 3D can't be done on that size airframe with a gasser.

PlaneKrazee

My Feedback: (14)

The plane he purchased does not have 3-d surfaces according to what I read on the website.

RysiuM

My Feedback: (1)

No, I didn't state it (at least I didn't intend to). You need power. No power - no 3D. In the fact I couldn't find a god definition of 3D so I came up with something that could define it: "in 3D you fly and turn the plane not from the speed (like airplanes do) but from the prop wash". So the most important thing is enough amount of the air moved by the prop to give a lift and push control surfaces (so big elevator and rudder helps).

What it means is, that airplane doesn't need to be aerodinamicaly sound (square pizza box can do 3D) but needs to be relitively light so wing can act as a drag and flane doesn't fly away when it supposed to stop.

Based on that definition 3D is not just hanging on the prop. I can do it with my SIG Kaded LT40.


Your statement is 100% true (but not complete )


I know that, you know that - but I really didn't see enything beter (overal). And this MVVS is a real beauty

No way, buddy. We are learning al the time - at least me. I take every word you write for good advise. Thanks for sharing. I will keep you posted.

RysiuM

rmh

I did a Funtana 90 with a Roto 25 on a tuned pipe - it was a fairly good 3D model setup -
the article is supposed to be out soon in 3DFlyer.
If you are truly serious about a small gas 3D airplane - first buy an engine - then setup for max thrust -THEN build a model which fits weight and wingloading parameters. (under 20 ozs to sq ft)
starting with a sturdy ARF is not an approach which will produce good results.
Oh yes don't look realistically at more than 15 pound static thrust with a quiet gasoline engine setup and a prop which has decent speed as well as thrust.
3D flying is in the eye of the beholder - one man's great 3D flyer is anothers pig.
just being able to hover (yawn) does not make a good 3D setup.

3D Joy

Now try to argue something about this .

Edit: Argue may be too strong a word so don't take it bad, that is not my intention .

PlaneKrazee

My Feedback: (14)

Dick is correct again.

RTK

My Feedback: (1)

Can't argue, I mean disagree, with Dick's statement. But don't you live at something like 6000 ft. too Dick?

RysiuM

My Feedback: (1)

Exactly

RysiuM

Xup

Be worth a look at the YW24,

http://www.ywengine.com


Claimed 15.5 lb static thrust

Engine weight 789 gram
Ignition unit 110 gram
Pits style muffler 90 gram

Total weight 980 grams, just over 2lb 1oz

RysiuM

My Feedback: (1)

From the quoted rpm it has less power than RSC 1.4 for 2 os less weight but a little more pricy.

However it's worth looking at - thanks for expanding my horizon

RysiuM

RTK

My Feedback: (1)

Maybe also look at an RCIGN1 g26 conversion. It weighs a little more, 2lbs. 6oz. less muffler and it has a verified 17+ lbs of thrust on my digital fish scale spinning a mezj 18x6 @ 9000+rpm

rmh

Unless there is something new about non tuned gassers - I still don't see any under 3 cu in gassers which will pull 15 pounds on a prop which is suitable for 3D use .
Ideally -you start with a 32 ounce engine and a tuned pipe (a very light tuned pipe) and setup for 8000 or more rpm static to get a workable 3D setup.
Our setup runs close to 10,000 in the air -that is not a misprint -we capture the rpm with the ignition tattletale tach.
Still the best bang for the weight was my 1.40 ST on small pipe with ignition and running 5% nitro and alky fuel.
This is a tricky size/weight to get right.
For me -the best bet was to simply divide my models according to "best power setup" and go from there
So --for small stuff - all electric-
inernal combustion engines cannot come close to providing the instant thrust of a electric motor.
For that neverland range -around 10 lbs - Go to a piped glow engine
over 12 lbs - gas engines
My 50 cc ZDZ on pipe runs 7750 on a pipe on a 22x8 -this gives fast rev up -which is mandatory for the slow speed flying of 3D flip and flit and tumble stuff.
The electric motors in this size weight beat it tho -BUT the cost of setup and batteries is verrrry high.
The reason they beat it?
Instant maximum torque --you can use a prop the IC engines can not even approach using .
You must use a prop on a IC engine that allows it to reach max torque--which on this size stuf is in the 7000-1000rpm range.
So which is best -is really a question of size and application.
We are at 4350 ft elevation here so our engines must be more powerful and our planes lighter -to equal any setup at sea level.
If it works here --it works anywhere.