Prop Nut

My Feedback: (3)

Hey J, did you ever see the flight videos of my DVII with the Briggs in it? Flew fine, just not a powerhouse. I was too chicken to fly it in heavy winds. But, even on a bad day (really humid, the engine didnt run well) the plane took off and flew, really slow, almost no climb but I did do one circuit of the field and then landed. Very scary but the plane is sooo stable and has soooo much lift! Here is the flight vid;

http://media.putfile.com/Fokker-DVII-Sunny-Day

and another day;

http://media.putfile.com/Fokker-in-flight

jtisch

Here's a pic of the 40cc on the test stand.

http://i78.photobucket.com/albums/j1...3Image0001.jpg

J

Prop Nut

My Feedback: (3)

Boy, it sure looks like the 34cc doesnt it?

jtisch

Yup, I have to be careful not to get the two mixed up! When got the 40cc first, I kind of freaked out and thought there was no way it would fit in the DVII. "After further review", though, and with the lucky purchase of a 34cc, I realized they were the same size externally. Speaking of lucky, this weekend I got an unrun Ryobi 26 4-stroke at a local garage sale for 10 bucks. Another project! I may be becoming a 4-stroke gas addict.

J

subarubrat

My Feedback: (1)

That's how it goes. You start selecting planes in a whole different way just to use the motors. I always tell people it is allot like electric in terms of the ease of use, but with a sound that 2 strokes can never produce.

jtisch

Propnut,
I haven't seen the videos because for some reason my browser won't let me. I'll have to either try on another browser or try on my wife's computer. Also, I wanted to ask you about the thrust angles on your DVII. How much down thrust and/or side thrust did you use?, if you can remember.

Subarubrat,
You are right! The Ryobi is very tall from shaft to the top of the cylinder head, so I started thinking HMMMMM, SE5a? DH4? I am going to have to live to 150 to build the models I want to.

J

jtisch

Well, let's see what happened today.

1. Ran the motor again with the 20x6, about the same results as yesterday, though today is a little warmer.
2. Took the muffler off, no noticeable RPM gain.
3. Put the muffler back on, same results.
4.Put on a 20x8 prop, got 5800- 5900 RPM but felt a lot more thrust standing behind the test stand.
5.Played with the idle, anything below 1800 and it started shaking quite a bit.

I kind of like the 20x8 prop. Any ideas on what the safe high-end RPM is for this engine? Personally, I'd rather lug it down a little bit than over-rev it.

PS: after a couple of hours and a couple hundred expletives, I got a spring back into the carb barrel on the 34cc carb,so now it has the tension for the barrel but not on the throttle arm.

J

Prop Nut

My Feedback: (3)

I put a 14inch prop on my 34cc just for kicks one day. It really wound up but no damage occured. I didnt take an RPM reading, sorry.

on another note, I am going to maiden my Fokker DVIII 1/4 scale tomorrow (I hope) with the 34cc Briggs on it. The plane is 15lbs so I have high hopes for the flight performance. Wish me luck.

jtisch

Best of Luck!

Is it the BUSA DVIII? If it is be prepared to put some down trim in. Don't let it stall on take off.

J

Prop Nut

My Feedback: (3)

lol, thats the third person today that has said that to me. I purchased one last year from a friend that had a terrible time trying to get to fly. I found that the high incidence in the wing was the issue. I shimmed up the wing and it took off perfect. The unfortunate issue was that the plane was around 19 lbs. Horrible wing loading. My new one is 14-15 lbs (if I can trust my fish scale it is 14.75 lbs) with the four stroke on it so I have high hopes of a good flight. Definatly set the wing incidence using and incidence meter, no matter what Balsa USA says. (not knocking Balsa USA, love thier planes)

Prop Nut

My Feedback: (3)

I want a 40cc Briggs! same weight, lots more power it looks like.

jtisch

LOL, but it's true. At the Dawn Patrol in August in Oregon, there were two new DVIIIs taking their first flights,mine(actually my father built it from BH plans) and another guy with the BUSA DVIII. My first flight went fairly smoothly but the other DVIII did several SEVERE knife edges on lift-off and only great piloting saved it (way to go Bruce!). There are too many good flying BUSA kits out there for me to disparage them, the DVIII is the only one I have heard grumblings about. In fact, I may be ordering a SE5a from BUSA soon myself.

J

Prop Nut

My Feedback: (3)

i know its true, like I said, I have had a DVIII already. It takes some tweaking but the plane will eventually fly good. The SE5 from Balsa USA is one of thier best. Flies like a trainer.

Prop Nut

My Feedback: (3)

The Fokker DVIII flew GREAT! It came in just under 15lbs with a Briggs and Stratton four stroke gasser on it. No balast was needed at all. The pulls up right off the strip and climbs great. I can post pictures and a flight video later if anyone is interested in it. Or, I might just do so whether anyone is interested or not I took the maiden flight, then a buddy of mine took the next one (did made me take it off as he said it looked squirley on take off, it is not squirrely. I just over corrected....several times, lol) then he took the controls so I could get a video of the flight. Thanks to Rob I now know that the DVIII will not do a knife edge...I just wish he had been alot higher before he tried it!! No damage, the plane tried but didnt lose altitude. Flew GREAT (Did I mention that?!) This is my first built from plans plane, I used new balsa from LoneStar Balsa. The hardware was reused from my last DVIII. This plane was CHEAP to build. The covering was given to me, the wing is balsa sheeted and then fiberglassed and painted with Krylon. The wheels, etc came from the last (now dead) DVIII. The engine...what can I say about the engine? No huge power but more than plenty to fly a 15lb airplane.

NM2K

My Feedback: (14)

Your DVII did not look underpowered to me. It looked as though it was powered in a very scale-like manner. Excellent flying too.

Prop Nut

My Feedback: (3)

Jtisch, sorry for usurping your thread. I just get so excited about these motors.

Artisan, thanks for your comments. The motor really is underpowered for the heavy DVII though.

Here are some pictures and a flight video. I had a friend fly the second flight so I could get video. He refused to take it off the ground as he thought 'It looks to squirley" Sorry for the poor quality, I was using my digital still camera to take video. It will work but doesnt look as good as a real video camera.


http://media.putfile.com/Fokker-DVII...-Stroke-Gasser

jtisch

Prop nut: Congrats on a succesful first flight! "mad props baby,yeah". Looks great. Keep us posted on how the inverted installation works out. Maybe one day I'll take out the Tartan on my DVIII and put the 34cc in, but that will be a lot of work as I would have to make a new recessed firewall.

Anyway, the only thing I did today on the 40cc to was rotate the throttle barrel 180 degrees. Sure enough, it did pick up @100 rpm on both the 20x6 (62-6300rpm) and the 20x8 (59-6000rpm). However, today was even a little warmer than yesterday and the motor started to sag. I may be lugging it down too much and overheating it, especially on my test stand, which somewhat restricts airflow. I don't think I damaged the motor though, as I let it cool down and tried it again. It worked fine.

J

jtisch

Did some more playing around today.

I suspect that the engine is not getting enough fuel at the top end, and not overheating.
Previously, I could get some good RPM numbers but they wouldn't hold. Idle was good , up to half/three-qurter throttle was good, after that was inconsistent. Today was the same, then I tried playing around with the choke(which I still have on) and got nice consistant high-end, although a 100-200rpm less than with no choke.

So, first of all, would you guys agree with my assesment?
Second, if you do,how best to richen the top-end without ruining the idle/mid-range?

Drill out the main jet?
Try to get to the high end needle?

any and all suggestions are welcome.

J

Flight Risk

My Feedback: (1)

Your 20" props seem a bit large even if it is the 40cc. Is it possible it's lugging a bit and/or overheating. I think you would want to prop it so that it gets 6500+rpm. Somewhere I read that it's not a good idea to mess with the jets or needles.

FR

Prop Nut

My Feedback: (3)

I have run my 34cc with a 20x8, it did fine at 5600-5800 RPM. I have never messed with the high end on the carb as thier is no "easy" way to do so that I know.

jtisch

Flight Risk:
I thought I might be over-propping it as well, but with the partial choke it would run wide open really well with no sagging or surging. I am going to try an 18 inch prop just to see what happens, though.

Out of curiousity, I checked the sears website for parts and the carb for the 34cc and for the 40cc are the exact same part number. My ryobi 26cc also has what looks like the same carb.

Next I think I am going to put the 34cc on the stand and see how that does.

Again, I am not an expert in this field so if you see any flaws in my reasoning, don't be shy saying so!

jtisch

Possible success. I "went for broke" and drilled out the main jet. It swung the 20x8 prop at 6000-6100RPM with no sagging or surging and no choke. I want to run it some more to make sure the idle and mid-range are OK but it seems alright so far. My wife was yelling at me to come in so further tests will have wait for now. Not too bad, seeing as the RCS 45-50cc four-stroke advertises 6000RPM on a 20x10.

J

Prop Nut

My Feedback: (3)

What did you bore it out to? How did you bore it out? The main jet is a tube sticking into the throght (spelling?) and the needle lets more fuel in the farther away it slides.....

jtisch

I bored it out to .017 inches(which is a #77 drill, I believe). I don't have a full set of these tiny drills now although I have ordered a full set. The main jet looks like a little servo grommet,not a needle, and is on the opposite end of where the throttle barrel goes in. In one of the threads on the WYL carb here at RCU someone posted a link to a diagram of the WYL carb,this was very helpful as I wasn't sure where it was

J

jtisch

Rats, with the .017" jet it will idle, but it starts to load up and the transition is not good. Will try .015" and .016" to see if I can get the best of both worlds whenever Mr. Postman delivers my drill bit set.

J