mattnew

My Feedback: (2)

Hi all, to start, I don't want this to get into a brand debate. vvrc and DLE both have an excellent 40 cc twin, and then there are a multitude of 30 to 35cc singles as well for sale out there. If I go with the twin, I know which engine I'm getting, if I go with the single I also know which engine I'd get. What I'm interested is in learning some of the trade-offs between a twin and a single and hopefully using that information to help me decide which direction I need to go here.


I'm building a 30% cap 232 that should come in around 13-14lbs or so ready to fly, so either engine should pull with quite a bit of authority
what I know so far
- twins tend to vibrate less
- all available twins will fit in the cowl I have
- 40cc twins and ~35cc singles spin about the same size prop
- twins cost more
- twin weighs about a 1/2 lb more

I'd really like to go with the twin, but I guess when I look at the numbers I'm not sure I'm seeing a compelling reason to go with a twin vs a single... and I'm hoping someone can give me some more information that may help.

Thanks in advance

Truckracer

My Feedback: (19)

In that engine size range, I still prefer a single over a twin for most applications. The 40 twins are nice but I just don't see the advantage over a simpler, cheaper 35. Even vibration isn't that much different as the smaller singles don't shake all that much to start with. Frankly I'm thinking the 40 twin thing is just a fad that will pass though there are certainly applications for both engine configurations.

Regarding your CAP, if it ends up in the 14 pound range, that's on the high end even for a 40 twin. If you are looking for 3D performance so you might consider a larger engine if weight is trending to the heavy side.

thailazer

I've been running a 44 cc Tartan Twin which is rather old technology but a strong engine. One downside is that you have twice the compression to overcome when you start them. My buddies with singles can merely flip them over by hand but mine takes a very firm and strong flip. Not less vibration either as Truckracer points out. I have the engine for nostalgic reasons, but the modern singles are a great choice these days and I will probably sell the Tartan and get a single just to reduce weight and make starting the engine safer.

mattnew

My Feedback: (2)

Thanks for the information guys.

I'm a tumbler. and a bit old school in thinking the cap is meant for tumbling, not 3D, so that is what it is going to be setup for. I have a 16lb stearman with an os gt33 in the nose that takes off at 1/4 throttle and will pull out of a stall vertically at 3/4 throttle. I get it has vastly larger wing areas than the cap, but flying that all last year I have a tough time going up to the 50-55cc engine sizes which is really the next option. It adds over a pound of weight to the plane in the nose, which likely means I'd start having to fight with balance issues to not have to add further additional weight to the tail. I admitedly am struggling a bit with lighter and slightly less powerful vs heavier and more powerful when it comes to the engine... but I think the plane will fly better with the lighter wing loading that would be provided with a 40 twin or ~35cc engine

ahicks

My Feedback: (2)

Here, 1/2 lb on a plane that size and type is a big deal. If we were talking Cub or something scale with a little more sedate performance envelope, maybe no (or as much) concern.

That said, there's the "cool" factor of the twin. As a self proclaimed engine guy fascinated with that kind of thing, I would love to be able to justify the purchase of one for that reason alone. My thoughts anyway. -Al

Cyberwolf

My Feedback: (4)

Just wondering what the wingspan of the cap is? My MXS-R14.5 lbs and Sbach14.00 lbs are both 30 % planes and I have my home built 55 single in one and my home built 60 twin in the other. The twin is by far heavier then the single. The twin flies the MXS-R very well for sport scale and high end acrobatics, but the single has way more power for 3-D type flying. Granted the single does shake some what more than the twin, but not enough to bother me or anything on the plane.
I am also at 4500 feet above sea level here and need the extra boost of the larger engine's to be able to fly the way I want to. I don't know what your alt is there but that would have a great deal to do with my engine choice, plus how you want to fly the plane. The Cap 232 use's the extra 260 or 300 wing and although the one's I have had flew well the wing loading was sort of critical to maintain nice slow landings I used A 50 cc to get the weight down and still had the power I needed.

mattnew

My Feedback: (2)

Wingspan is 80", so I guess officially that makes it 25%, not 30% as the kit "advertises"...its really not that large of a plane... Honestly I will be dissappointed if I end up at 14lbs, I really think I can get it in under 13, maybe around 12.5 lbs... we shall see....

I'm 15 minutes from the ocean, so I can't be more than a couple hundred feet above sea level if not right at sea level.

av8tor1977

My Feedback: (6)

Unless weight is a strong issue, I would go with the twin myself. I just like the sound and smoothness of them so much... If you're going to use smoke, a twin produces a slightly better smoke trail too.

I have lots of engines, but my 48cc, 50cc, and 100cc twins are my favorites.

AV8TOR

Truckracer

My Feedback: (19)

av8tor, like you I love twins but for the smaller sized engines I think they are borderline on being practical. Just my opinion you understand. Its probably a matter of application in some cases though where one engine configuration would work better than the other. But, I bet in most cases it is just the cool factor and the owner just wants a twin!

Kinda like the really small gas singles (10cc or so) coming on the market ... I often wonder if they are worth the trouble compared to a good glo engine but for the owner, gas is cool even if there is no place convenient to put the ignition box.

mattnew

My Feedback: (2)

I have the 10cc gasser and a 15cc gasser, both by evolution. They work well, though different from a glow engine. more torque, less rpm, so they fly differently... my planes are slower, but have more vertical than with comparable glow engines.....for whatever that is worth..., your 100% spot on on the "where to put the ignition" and extra battery conundrum.

decisions.... I really want a twin... but the gt33 I have is an incredible engine... I wouldn't mind buying another of those for this plane.....


what I might do is get the plane a bit further along and see what the balance is like. if it is tail heavy with the 33 I have I might go for the twin to get it to balance....

av8tor1977

My Feedback: (6)

I'll admit the "cool factor" is a draw for me on this one, but I just love the phenomenal smoothness and great sound of a twin too. However, if I were looking purely for performance, or if I really needed to keep the weight down for either 3D flying or to keep the wing loading reasonable on a low wing area plane, I would definitely go with the single.

My personal "line" for gas is at 15cc, though I tend to think 20cc is a more reasonable line. I only say 15cc because I do have a .90 size Super Tiger converted to gas and I enjoy it a lot. Bill from CH sent me an updated, smaller ignition system, and that, combined with using a single battery for the flight pack and ignition helps a lot with the smaller planes. I don't even use the Aero-Tech IBEC and have had virtually no problems after many, many flights. (Hitec Aurora 2.4)

Hmmm, I just looked at Adrian's CH Ignitions site and he is still selling the original style in the metal box. I guess maybe this one I got from Bill is not being produced....

Anyway, I still enjoy glow too. I have a Twist 40 with an old Fox .78 on it that is just a blast to fly. The dreaded "clean up" of a glow plane isn't really all that bad, especially if you use an exhaust diverter to keep some of the glop off the plane. I still like the sound of a glow screamer, and the smell of methanol/nitro. Reminds me of my drag racing days, and many fun years of flying glow.

AV8TOR

Truckracer

My Feedback: (19)

I played around briefly with one of the 10cc engines on a friends plane. I kinda liked the different torque curve the little gasser had. It was quite different from a glo engine and I'm not sure the owner ever got use to the difference between the gas 10cc and similar glo engines he had. Also not sure he ever accepted my explanations why there were differences and as a result, I'm not sure he ever really reached the engines potential. These little engines certainly have their place in our hobby but not for me at this time.

av8tor1977

My Feedback: (6)

A lot of people don't understand that to speed up an airplane with an engine that has it's power peak at a lower rpm, all you need to do is increase the pitch of the prop to compensate. Of course you have to juggle the diameter then too, but it is important to prop an airplane/engine combo for what you want it to do. I always laugh when someone asks, "What prop should I use on my XXX engine?", and don't give any other info.

AV8TOR

Truckracer

My Feedback: (19)

I believe that prop selection is much easier with gas engines than it was with glo. It seemed that glo engines always had to be screaming their lungs out to make good power where the broader torque curve of gas engines gives a nice even pull throughout the rpm range. Looking back though, I think that all too often I propped my glo engines with too small diameter and too much pitch but that is what was the accepted "norm" during the day. Of course, racing applications were different.

Back to the twin discussion, singles and twin gassers seem to have a different feel in the air with overall throttle response going to the twin. Not sure why ....

Cyberwolf

My Feedback: (4)

(Back to the twin discussion, singles and twin gassers seem to have a different feel in the air with overall throttle response going to the twin. Not sure why ....)

I will second that one hands down, the twin is so much smoother on the throttle it is really no comparison.

Desertlakesflying

My Feedback: (28)

Go with the VVRC 40 twin 1/4-32 and you will not be disappointed. I have one in an RedwingRC 30cc MXS-R and one in a Hangar 9 Valiant 30CC. I run them on 100LL and 35-1 oil.

Get one before they are gone they sell out fast.
http://www.valleyviewrc.com/estore/vvrc-40cc-gas-engine-w-1-4x32.html

Cyberwolf

My Feedback: (4)

Your dealing with an 80 inch plane the same wing span as my Midwest extra was, it weighed in around 12-1/2-13 if memory serves me correct. But it was not in any way a 3-D machine. But I flew that with a 50 CC for years and still would be if I can get another wing for it. So at sea level you should be able to handle the extra weight of the twin W/O any problems.
Idea!!!!! I'm going to send you a PM.

airraptor

My Feedback: (66)

I have read the VVRC 40 twin is much stronger than a DLE 35RA. the twin spins a Beila 18x10 3 blade at 6600 and the 35 RA is about 5300. I sold my 35RAs I had for a twin project and ordered to VVRC 40 twins.

mattnew

My Feedback: (2)

Just so happens it is a Midwest Cap232 I'm building, which has the exact same wing that the midwest extra has. I sent you a PM back. Kits/plans are still available from midwestproducts as well ... as an FYI.

"Not a 3D machine" doesn't bother me in the slightest... I'm quite honestly a "how violently can I make this plane snap roll, lets see if we can get better than 420 degrees per second out of that roll rate" kinda guy. waterfalls hoverring and torque rolls 3' off the ground are by no means easy... I've screwed those up plenty.. but they aren't fast enough for me :-)

This right here is what gets me out flying... take a look at 1:03 .. he stops a lomcevak in mid tumble and is flying backwards until the power of the engine gets him going the other way again
just too much fun...
https://www.youtube.com/watch?v=ihLSBClAPfU

@truckracer: while I do like my 10cc, I definitely get that its not for everyone... its tough to find space for all the equipment, ignition ends up being next to your receiver... and adds a lot more weight when compared to the .60 sized glow engines. I have hope that O.S. is working on the ignitionless 10cc gasser next after their 15cc one.

Truckracer

My Feedback: (19)

We have several of both the VV40 twins and the DLE35RA at our field. While the 40 is stronger and it should be, it is not night and day stronger. I'm thinking the RPMs quoted above were from a not so strong 35 and an exceptional 40. 1200 RPM is a considerable power difference. They are both very good and strong performing engines. Reports are the DA 35 is stronger yet but I have not yet seen one run.

airraptor

My Feedback: (66)

well it might be but from the guys flying that props is what they posted. i tried to run that prop on a DLE 30 and only got up to 4600 rpm or so. Some have said that prop is the same load as a XOAR Laminated 20x10. I will find out soon once I get mine.

sensei

The Midwest 27% 80"Cap 232 is a sweet flying airplane for sure, I built and flew two of them over the years, one had a Moki 1.8 on the nose @ 16 lbs. the other a BME 44cc single @ 18 lbs. A buddy of mine built one that weighed in at 21 lbs. with a G-62 on the nose that also flew very well. None of these were 3-D airplanes but again flew very well. Realistically unless you place that airplane on a diet during the build they tend to come in a little on the heavy side by today's standards, but honestly an airplane doesn't need to be 3-D capable to be a great flying airplane. Here is a picture of my very old Midwest 80" Cap with the 44cc engine.



Bob

mattnew

My Feedback: (2)

Pretty plane Bob. Caps look great in yellow. The only major change I have made so far was I swapped out the kit wood for contest balsa for all the sheeting. On average it was about half the weight of what came in the kit. The wing weighs 2lbs total, the body just under 3. thats without covering and I haven't finished the nose of the plane on account that I haven't decided on power plant.

What can you tell me about the challenges getting the plane to balance with a BME 44 in the nose? The G62?

sensei

As I recall I moved the rudder and elevator servos into the tail and the battery pack aft as well. The Cap with the G-62 actually flew spectacular IMO, and to be honest, if I ever get my hands on another kit of the Midwest 80" Cap 232 I will place it on an extreme diet and place a DA-50R in on the nose.

Bob

mattnew

My Feedback: (2)

not too hard...

http://midwestproducts.com/products/disc-cap-232