H9's Sundowner

[CRG]

Hi Mike,

Last time out I'd say it was doing about 110-112mph, just a fraction faster than the EVO35 version. This is on 25% nitro and an APC15x12 prop. It does use a lot of fuel, 20ozs. is good for around a 10 minute flight and no more.

60% nitro is a little excessive. As mfuess says, it'll only take that for so long. And you need a lot more power to go a little faster. I flew competition old timer for a while running high nitro in four strokes and they would eat pushrods and other parts fairly regularly.

One thing the Sundowner likes is to be light. The Saito will keep up with the EVO, but will out turn it at will, almost three pounds less makes a huge difference in the corners.

Got the CD of your Parker pics, great job Mike.

Craig.

	Quote: Originally Posted by rcplane
	Hay CRG How fast are you going with the Saito and what Nitro % are you using? There are 6 guys here with 180s in their Sundowners and 2 or 3 are burning 60% Nitro! We clocked one @ 135 (with a Bushnell radar gun) but it wasn't really getting all it had I don't think. I have to try to keep up with these guys with my Evo 35! I cant remember where I read it but there is a guy who says he is getting 145mph with a Moki 210? A DA-50, WOW! PS; Get your pictures, this is Mike B

[Sparky69]

I echo CGR. My Sundowner won the race at Parker and it wasn't the fastest plane on the course see my prevoius posts. Race #3 is the most studyed Sundowner with about 25 flights with full fdr down loads. From my data I don't think a Moki is running 145 MPH but I am not done testing. Again see my previous post about speed on the course not flying in a dive for a mile maybe.... It also has to hold together in the turns, I'm not confident that at 145 it would stick together.
I disagree the GPS speed is more reliable than what I am doing. It would be nice to have that as well and if you want me to install the GPS unit send checks my way. Remember I am recording all the time and can clip out a 2.5 minute sample from my data to study as I am wizzing around a simulated race course not a one time snap shot from a radar gun.
Sparky

[mfuess]

Sparky69,

I am in total agreement with you and CRG. I put 2 flights on my BME 50 powered Sundowner yesterday and it was a little disappointing, even though I did the math prior to flying it. I had expected a little more in real flight. With everything being brand new I used a 16x12 prop to hold it back a little. Boy, did it ever! My best peak speed was a piddling 107.6 MPH as documented by my flight recorder and confirmed by my calculations. Each lap I pulled the Sundowner closer to the poles to see where my limit is on how sharp it will turn & retain most of its speed. About 170 ft. is as tight as it will do right now. I expected that under the current conditions. Today I will try a 16x14N. That "should" push the Sundowner to about 128 give or take a little. Once the airframe has proven to hold up, I'll move up another pitch or two and see where that takes it.

The only redeeming thing is, it will fly for 40 minutes on 20oz. of gas.

[Sparky69]

M Fuss,
I over looked the GPS tracker giving radius of turn. You should be able to dial that down some. I think when we did the math we predicted 100' turn Dia (50' radius). Are you talking Radius or dia turn?
Sparky

[rcplane]

Why the smaller prop on your motor CRG? Shouldn't a Saito 180 spin a larger prop like was used on the EVO 35's at Parker? Wasn't it a 16x15?
It seemed like the parker prop made my plane much faster than the 15x12 I thought we were going to race with. I wasn't sure it was going to pull it when I first heard about it's size but after a couple runs it really liked it. No heat problems or anything.

On the fuel, one of these guys burn's up Saito's like they are free using that high Nitro, seems silly to me but then I don't have a big pocket? They dead stick a lot also where I never do with my gas!

I want mine to be able to fly in USRA races so I am going to keep the EVO35 in it, besides it really doe's fly good.
I also agree Sparky 69, I am not sure it would hold up to 145 mph. I was sure I could see the wing bend in good tight turns with the EVO35.

I thought mine was right at 13.5 when I took it to Parker but when it was weighed at the race, it was 14lbs. (poor home scales). I do still have the large solid rod in the tail but had to leave it in for balance (even though I have my rx battery in the tail).
In an effort to get mine lighter before Parker I removed the one rod, then moved everything back, ign, fuel tank (and smaller tank) and a tiny 2 cell lipo for ign to get it to balance.
I was curious as to how guys had gotten their planes lighter, then I found out about the light weight radial motor mount in Parker for the Evo35, with it in place of that huge stock motor mount and the large rod removed I will be much lighter. It might even be too much and go under the 13.5 the USRA has set.
The guys here with Saitos are 11.4-5lbs without trying? Hard to compete with that.

Some club members are trying to get some racing going here in a couple different classes, Sundowner, Q-500 type and a few others. I am going to try (for the club) and get a waver for some of the distances as they are quite large and even though we have a big place we still fall short of some of the AMA's set distances.
We keep safety first but can't meet a couple of those distances and as I just learned about the waver it sounds as they are quite common. As long as your request is sensable.
They are leaving the motor size open on the Sundowners and I am not sure they will get approved that way, although top speed can't exceed 135mph.

Does it still sound like the USRA will keep the EVO 35 on the Sundowner for 2008?
Or change to the Moki 210?

I can't wait to hear what Mfuess ends up with for top speed!


Mike

[mfuess]

	Quote: Originally Posted by Sparky69
	M Fuss, I over looked the GPS tracker giving radius of turn. You should be able to dial that down some. I think when we did the math we predicted 100' turn Dia (50' radius). Are you talking Radius or dia turn? Sparky

It's a 150' Dia. or, 75' Rad. I can pull a tighter turn, but I noticed a fairly substancial speed loss. My speed recovery is good, but it could be better. The Sundowner is rock solid in tight turns. I read somewhere that it yaws a bit in a turn, however I didn't see it. I flew a couple more times yesterday trying to get it all dialed in. I'm still disappointed in the speed. I switched to a 16x14N APC and it tachs 9720. This should have yielded 128.6 MPH. Instead, I got 100.6 MPH. That's 7.2 MPH slower than before. Dammit... OK, this tells me that it needs more thrust on the topend to overcome the drag. So narrow props are OUT. I'm fairly sure I can pull a 16x16 with authority but I won't know until I SPEND more money on props.

I think I'll fly my Rearwin Speedster today...

[mfuess]

I suspected and confirmed that my stock muffler creates too much backpressure at higher RPM's. I looked all over the internet attempting to find a header & pipe. I found a pipe, but no header. So, I made one. I won't see the pipe for several days, but I have no doubt it will un-leash the topend. Maybe, just maybe this will get my Sundowner up to my expectations...

[dptp9lf]

I thought about putting my ZDZ Super 80 in the Sundowner... maybe that's what it will take?

[Flatlandman]

That would need more work than the da 50 for sure lol but I bet it will haul ass.

[dptp9lf]

Probably be a trade-off in flight characteristics though...

[mfuess]

I managed to hit 123.9 MPH today just by changing the exhaust. I knew that stock muffler was holding it back!

[mfuess]

My 25mm header allowed the BME to un-load the air taching 10,890 RPM, thus pushing the Sundowner up to 123.9 MPH on a 12 pitch prop. I have a lot more speed (and power) available if I bump up the pitch to 14, 15, and possibly 16.

However, I can't really run an open 25mm pipe as the noise is totally un-bearable, 119db @ 1 meter. So, to correct this without giving up too much power I made another header to stand away from the fuselage a bit more, then I modified an MTW 75cc canister to allow the 50cc to un-load as though it was an open pipe. (HOPEFULLY)

[Flatlandman]

The sound I got from the straight header was also very loud but is no prob in the air. OUr feild doesnt have any noise restrictions and being near the landfill has no houses closer than 3 miles away other than a barn or 2.

[mfuess]

We have a residential area about 1/3 mile away, so we try to watch the noise. I like the canister! It lowered the noise 23db, plus I got an additional 1250 RPM out of it. I spun an APC 16x11 at 11,830 RPM to see how noisey it would be... the prop got up to 110db.



I should see about 130 to 135 now. My last recorded speed was 123.9 on the 25mm pipe and now I have an extra 1250 RPM to play with, plus whatever it unloads at in the air.

[rcplane]

Wouldn't you get more speed with say a 16x14 prop at less rpm's?

Mike