Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
This project started a year ago, with the purchase of a Sears Weedeater. The weedeater had a Briggs and Stratton 34cc four stroke engine. First thing, off with the engine and see if I can convert it for RC. With a prop spacer from Wacker Engines, a flat plate for an engine mount and a bandsaw, I had an airplane motor. I put the engine on a Giant Stick (96"wing) I resurrected using the fuse off an old Eindecker "wanna be" and a new wing, this plane was just for testing engines so I didnt bother with finishing the wing joint. This spring, I flew the plane for several months. The engine is quite heavy, at 5.11 lb. Total wieght on the Stick was 25lbs. It seems to fly fine, but was, to my mind, a little underpowered for takeoff and manouvers. This fall, at the beginning of October, I decided to take the plunge and build the plane that I had in mind all along for the four stroke. I had seen Greg Hahns Balsa USA DVII with the Fuji four stroke at Warbird over Indiana in 2004, and loved the combo. With the cost of Fuji at around 800.00 at the time I didnt even consider buying one.....but what if I could convert something else? I purshased the engine and then this spring I purchased the kit. The plane was ready to fly last tuesday, I didnt bother painting or detailing until I found out if the combo would work or not.........I have to say, it was a huge success! I dont know yet the wieght of the plane but it seems to be right around 22lbs, this sounds heavy but this is a huge plane. The maiden flight; Take off rollout was about 25 feet, I didnt have to force it in the air,a little elevator and it leaped up. turns were very easy with great response from the control surfaces. A couple of circuits and back down to check it out. Landing was like a feather, it just floats down. I refueled for the second time, no soon had I started pumping than the gas was full, I am not sure it took more than fumes to run the motor as long as I did (quite a long time in the pits before the first flight, I did a radio check with the engine running and several RPM checks). Again the plane lifted at around 25feet rollout, I pulled up on the stick fairly heavy to see how it would climb, at around a 30 degree angle it just kept going, plenty of power. I did a stall test, forward and slowly sinking, no bad tendancys. I didnt do any loops or rolls as yet, just wanting to find out how it flies, I did do a couple of wing stands; Perfect, didnt drop, just kept going through to a wing over. Another great landing, I actually had to give it just a little down elevator because it likes to float. One of the pictures below is exactly at wheel touchdown on the second landing. All in all, I love this combo and the plane is exellent. The kit is easy to build, and quick. The engine? I paid 100.00 for it on Ebay, 18.00 for the prop spacer from WackerEngines.com and 10.00 to have the weedeater shipped to me. A grand total of 138.00 for a great running four stroke gas engine.
RPM stats, This is not a powerhouse motor, if you want one of those, buy a DA50 But for flying this plane, its perfect. The night before the maiden, I was using a lower octane fuel, I had 6500rpm with an 18x6 prop the day of the maiden I tried the highest octane and recieved 200 rpm less (ok engine guru's tell me why that was). I was actually getting 6900-7000 when I was flying this engine on the Giant Stick but have since tried to mess with the mixture (had to dig epoxy out of the end of the carb barrel to get to the set screw) and as a result lost some RPM.
Posts: 67
Joined: 12/10/2004 From: , IN, USA Status: offline
Hey Propnut- The Fok.DVII is very cool. I would like to build a big scale gasser one of these days.
YOur new engine, the one from ebay - was that a weedeater in stock form? I have heard about doing these kind of conversions, and it seems like such a cheap way to power a big model. THe conversion sounds very easy to do.
I have a friend who has been talking about going gas... maybe I will convince him to go spend some money? I love helping other peopple spend their money!
Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
"As always"? Tom, has Randy seen how messed up my planes usually turn out?! But I thank you for the compliment. Took the DVII out today for a couple more flights, it flew great! The engine on the other hand......kept cutting out on my in turns........I gave up for the day, tried to pump the gas out and found out it was empty.......EMPTY?! i said to myself, that cant be, it will run an hour on a 16oz tank (no lie) how can it be empty.......well, tip the nose forward and the gas will pump out..........my clunk was stuck forward!!! I am guessing that it did then when I disassembed it for painting, I had it sitting on the firewall while painting etc. I need to take it out and fix that but otherwise it is a great running motor.
Mustang....to answer your questions....I purchased the used weedwacker as a running and usable unit on Ebay for 100.00 with 10.00 shipping. It functioned perfectly when I recieved it. (Took it out to the field and cut down some winter wheat, lol) You can however purchase the power head from Briggs and Stratton (through a small engine repair shop) as a friend of mine did, he purchased three of these motors (one for a Spad XIII he is building and another for a twin someday) an paid right around 139.00 each. This included everything to run the motor right out of the box, minus the shaft, handles etc that a full weedeater needs to function. The same conversion techniques are needed. Wacker Engines sells the prop spacer for 18.00, it is the same spacer that a US41 or Quadra50 uses, just screw it on.
Posts: 139
Joined: 4/13/2004 From: groveton,
NH, USA Status: offline
Great save, will keep an eye on this...luv four stroke but hate the cost of glow fuel for giants...luv the thought of gas as long as I don't have to put it in my car. thanx, ken
Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
Here is a picture of the new Aces of Iron figure, made exclusively for SR Batteries. Johan started his military career with the artillary, after volunteering for the air service and a year in scouts he was transfered to a Marine Jasta to fly the new DVII. Far up in the clouds the very air freezes, Johan has learned that his Artillary great coat is far warmer than the dashing but chilly leather flying coats that have been issued to new pilots.
Posts: 5152
Joined: 2/13/2004 From: Zentsuji, JAPAN Status: online
Looks good in the air! So now that you know it flies what kind of detailing are you thinking of doing? I'm one of those sorts who can't stand to fly a model until every last rivet and grease stain has been added. But then that's probably because I'm such a terrible pilot there's a very good chance that the model won't made it down from it's maiden!
Just curious, what do you feel are the primary advantages of a "gasser" for a model like this. I suppose I don't actually fly often enough to care about the cost of fuel.
Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
Well, for me it is a matter of cost. This four stroke gasser was 138.00 (I actually did this one only for the sound). A glow engine large enough to fly this plane would cost me in excess of 300.00. I do alot of conversions, I have a 1/4 Pup that will use a 25cc homelite. I had a .91 size Eindecker (Balsa USA) that had a 25cc Poulan, My 1/4 Fokker DVIII used a 33cc Homelite chainsaw motor, my 1/4 Aeronca (Bud Nosen kit) uses a Ryobi 25cc. All of these motors (including the four stroke) cost me less than 200.00. All run great and fly the planes perfectly. I enjoy converting engines as much as building planes, its always fun to see what you can do with an old weedeater or leafblower from a garage sale that cost 5.00. The Gas over glow question is a good one also. I dont have to clean my planes off. If I have them running right, nothing comes out the exhaust except hot air (Alot like a Master Sargent I once had). No guey stuff to clean off the wings etc. I love the sound of a gas engine over even a four stroke glow, especially a four stroke gas, lol. I have not built a motor that will do 3D and have no idea how I would. None of my motors are power houses, but they fly the planes that I like very well indeed. I have seen several conversions that will though, so it is possible to compete (on a local flying field that is) with the high dollar engines. No glow fuel to buy, no glow plugs to change, no glow plug igniter to remember to bring to the field, no clean up supplies to carry around, and huge props to make my planes look more scale. I love em. I am not saying that gas is better than glow, because I do not believe that for a minute, both have thier points. I personally like gas engines.
Details; I did the personal insignia last night with the four aces. I will get around this winter to doing the cabanes and sub wing. I have the parts to do a pretty good scale mounting system for the machine guns (provided for me by one of the friendliest guys I have ever met online, Roger over on RCScalebuilder.com) and several other little things. Nothing to fancy, this is going to be an everyday flier. I am not huge into scale, just dont have the talent nor the patience. I love to fly. Thanks for checking out the thread, I have been watching your N11 also, love what you are doing. And I really liked the wheel comparison. I to have several sets of each and like the flair best.
Posts: 63
Joined: 11/15/2005 From: Northeast,
OH, USA Status: offline
Prop Nut,
Great looking bird! I've always loved bipes.
I've been reading alot of the Briggs posts on RCUniverse and finally signed up to post some. I have seven gasser engines I've saved from the garbage men, all marked for RC use but I had to buy a Briggs off ebay to get a 4 stroke.
How did you get the pull starter-clutch group off the shaft? I can't get a wrench past the starter cogs to get to the nut by the flywheel.
Also, do you happen to know what compression you have? I've got good spark and 30PSI but can't start her.
Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
I pulled one apart today, I levered the studs for the recoil springs off with a large flat head screw driver (its not easy) and then getting a box end wrench on was pretty easy. I tapped the wedge of the screw driver in to raise it out of the pit. Takes some time but it works.
Posts: 1556
Joined: 5/4/2004 From: Coral,
MI, USA Status: offline
An update, I blew the engine. Was flying it in below freezing weather......well, right on the edge, it was 35degree's. With no shrouding around the motor to keep it hot we are assuming (everyone that I have shown the motor to and knows anything about motors that is) that without the shroud to keep the engine protected from the cold, the extreme difference in temperature inside the crank case and outside (the outside was almost cool to the touch when I landed and the backside was burning to the touch) would (could?) have caused small pieces of the inside to pop off (anyone ever put hot water in a freezing glass? Same principl
Printable Version
All Forums >> RC Airplanes >> RC Warbirds and Warplanes >> Balsa USA Fokker DVII w/4stroke gasser 
Balsa USA Fokker DVII w/4stroke gasser - 
But I thank you for the compliment. 
