jjscott

Does anyone know of any short gassers ones that have a crank centerline to top of plug wire dimension of 5 inches or less.

There are some ~26cc engines that might work, but I'm looking for something a bit larger. Application is a WWI Camel biplane with a 10" diameter cowling and a short nose. A side carb would be much better than rear, and front carb may not allow the use of a dummy rotary. I don't want anything hanging out the bottom.

I spent time looking on the net for dimensions. These won't work: G38, G45, RCGF 45, MVVS 35, EVO 35, EVO 45, ZDZ 40. There's got to be a lot of Balsa USA 1/4 scale Pups out there. Anything fit completely inside?

I'd love a 4 stroke like a Laser 200 twin, but these are VERY expensive.

Jim

buck1856

My Feedback: (49)

Heres 2 that i have:
My sons Balsa USA 1/4 scale DVIIIhomelite 30cc5-1/2 inches centerline to plug boot.10 inch cowl.5-3/4 from firewall to hub face or back of prop.you can see the clearance.Flys plane really good.Most of the time 1/2 throttle,maybe a little more.Still trying to find the sweet prop.
My Jerry Behrens scratch built 1/4 scale sopwith tripehound[tri-plane].80 inch WS.11 inch cowl.Quadra 35,with cup mount and spring start.6 bolt hub.Rear exhaust,rear plug.5 inches from center line to head.3 inches of room to spare completly around cowl.My firewall is moved back an inch or so to accomadate this engine though.Thats the way the plane was desighned.If you can find a quadra 35,42,running for less than 100 bucks.go for it.Just move the firewall back a bit.I doubt you will be able to kill the engine.Ill see what else i can find.Pics on left are DVIII.Next 2 are mine.
UPDATE-just checked my sons giant scale corsair hes building.Has a 10 inch cowl.Calls for a US41.so i know the diameter is fine.Sold mine so i dont know the distance from center of crank to boot.

jjscott

Buck1856, thanks, this is exactly the kind of information I am looking for.

On the Quadra dimension, is the 5" from the centerline to the edge of the head, or to the outside of the plug boot? Do you think there's enough room behind the prop to install a dummy engine?

I've found it a bit odd that many engine manufacturers/big sellers don't give 3 views with dimensions, and dimensions that include the plug. I bet 90% of gassers are cowled; everybody wants to know whether they're going to fit.

Jim

buck1856

My Feedback: (49)

OK,heres a few more pics.One of them showed from the side shows 1 inch of clearance between the flywheel and edge of cowl.Dont know if thats enough for a dummy engine or not.Battery cdi would be better.Unless i just made the center of the dummy cowl as big as the flywheel.Wich might not be that bad because youd see the center turning as if it where real.Nice thought.
The 5 inches is from the center line of the crank to the top of the boot.I use a short plug and since the hole is angled you can see in the pic its even with the head.
Another pic shows how the engine is installed in a box with the firewall moved back[2-1/2 inches,not 1,,my bad].
You will also see the flat pitts muffler behind the engine right above the cup mount and the exhaust stack just even with the bottom of fuse.
Another pic from the front youll see that the engine cannot be seen at all,even underneath.No cutting the cowl at all.
If i where to do my sons Balsa USA DVIII in this configuration,making a box with firewall moved back it would duplicate my sopwith perfect.But my sopwith is an 11 inch cowl.The US41 i dont remember if it was rear exhaust but i know the quadra 42 is for sure.
I think the reason some engine manufacturers dont put there actual finished dimensions and weights on there site, ect.. is noone would buy them.

jjscott

Those pictures are great. I found a Canadian Quadra site: http://www.quadraaerrow.com/ that gives dimensions. Without the plug cap the Q400 (40cc) is 4.75 inches; I blew up their 3 view on the copier and got 5 1/4 to the top of the cap. I think I can live with that. Your photos confirm it.

Now the issue is length. I'd have to push the firewall back and open up the bottom front of the fuse. It would mean altering the front gear leg mounts, but, again, your photos show how to do this. Quadra Aeerrow sells an EI version of the engine, which makes it a lot easier to install the dummy motor. I've got a Mick Reeves kit, so all the motor parts are included. I don't think his rotary would work with the magneto flywheel.

I trying to find something on the US 41.

Jim

buck1856

My Feedback: (49)

I learned this after my son and i built his DVIII and my sopwith was already framed up,and covered.Never flown,so im restoring it.Anyway,just about all WWI fighters at least the axle is directly under the cg.This is why they always like to nose over for no apparent reason.Thats also why they had that stinger that pointed out the front of the real ones when they where flying off of rough fields.And why a lot of pics show them on their nose all the time.What i was told to do by a pilot was to move the front leg of the gear a half inch forward.This will move the axle 1/4 to 3/8 forward of the cg and it wont have the tendacy to nose over.Your cg will stay the same though.I also just looked at my echo 45 cc and it will work also but the length from center to the boot is 5-1/2 inches.Width is only 7 inches.Im going to check one more item.

NailMan

I use the engine [link=http://picasaweb.google.ru/nailalex/Sopwith_Camel_1to4#5234444024329195746]dzy48 twin[/link] on my 1/4 semi-scale Sopwith Camel (WorkInProgress).

Only candle caps will be put out for cowl limits on 10-12mm. Candle caps can be disguised but on the first estimations a kind will not spoil. All engine is located in a motor compartment freely enough. Exhaust branch pipes of mufflers should be cut off and probably to bend forward.

And...The sound of the boxer is not comparable with the one-cylinder engine that is much more pleasant for hearing and a general impression from model such as Sopwith!

jjscott

Where is the DZY engine made, and who sells them? That's a nice installation and it wil easily swing a scale prop.

I emailed Quadra Aerrow about the Q400B, but never got any kind of response; I don't know if they are still in business. Bennett seems to sell the engine, as it's listed on their web page. One turned up on ebay, and I bought it. The design of the crank nose will easily allow a dummy engine to be used. But for the very tip of the plug boot it will fit in a 10" cowling. I do like the idea of a twin, though.

I'm waiting to actually have the Q400 in hand to work out the firewall position and the effect on the front gear legs. There is a cross piece that goes between the front mounts that will have to be changed.

Jim

NailMan

The motor the Chinese, its analogue for example [link=http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5733&Product_Name=SV_50cc_Twin_Gas_Engine_CDI_3.13kW]SV-50 Twin[/link].

Unfortunately I do not know who in the USA sells (and whether sells) engines DZY Engines. One my friend has bought SV-50T and on dimensions it is very similar to mine DZY48, only the shirt of cooling of cylinders is a bit more in size.

On the Sopwith Camel I at designing have extended at once a nose that the engine was normally entered on length and was everything is all right with position CG.

jjscott

Nailman, thank you. I do remember US sources for the SV engines. I could not get your link to work. Jim