H9's Sundowner

[mfuess]

	Quote: Originally Posted by rcplane
	Wouldn't you get more speed with say a 16x14 prop at less rpm's? Mike

That's correct Mike. I ordered an assortment of props yesterday ranging from 16x12 thru 16x16. Plus one 16.5x14. One of these props should be the magic number...

I ran the 16x11 mainly to hear how much prop noise to expect.

[mfuess]

	Quote: Originally Posted by dptp9lf
	I thought about putting my ZDZ Super 80 in the Sundowner... maybe that's what it will take?

Actually, you would be very disappointed.

[dptp9lf]

Not that I was serious about the ZDZ 80 install... but how would I be disappointed other than the fact that it would be too heavy, I would need a taller landing gear, it would shake it apart, and it would be a sled in the turns?
Cheers,
Lyle

[mfuess]

	Quote: Originally Posted by dptp9lf
	Not that I was serious about the ZDZ 80 install... but how would I be disappointed other than the fact that it would be too heavy, I would need a taller landing gear, it would shake it apart, and it would be a sled in the turns? Cheers, Lyle

Hey Lyle,

You pretty much covered it... I have a BME 50 in my Sundowner, and so far the best I have see is 129.7 MPH. I've spent a fortune in props, and still can't break through 130. I've changed to a super high-flow exhaust system and I'm taching some rediculess RPM, still not breaking through.

[dptp9lf]

Hi mfuess...
I came really close to putting the ZDZ Super 80 on the aircraft attached which is a Jack Devine R4 Firecracker. http://www.jackdevinemodels.com/firecracker_r4.htm I opted out and went with a Aeroworks 75cc Extra 260 as I don't really have the time to build the R4 and I also like IMAC aerobatics.
I was looking at speeds of 140+ when researching it. I was sold on Supercool's props http://www.supercoolprops.com/price_list2.php He recommended the 18X20F1 that many of the USRA guys run on 100cc engines... that's what he told me anyway. These props are $100. That prop seems to me like it would be about the right size for your 50 but it would be an expensive test.
I also attached my prop chart which you probably already have something similar.
Looks to me like you hit a wall with it and it's going to take something drastic to get through.
Cheers,
Lyle

[Flatlandman]

The guy I built the sundowner for said he didnt mind if he had to buy a 100 dollar prop but we both didnt want to take the chance it didnt work and have a 100 dollar wall decoration to show for it.

[dptp9lf]

Heard that Flatlandman... wouldn't take long to tie-up $500 in wall decor... that's part of the reason I didn't build the R4 as it would have required a lot of R&D and I just don't have time for all that. With the aerobatic ARF's you just go out and fly with what works for everyone else.
cheers,
Lyle

[mfuess]

	Quote: Originally Posted by dptp9lf
	Hi mfuess... I came really close to putting the ZDZ Super 80 on the aircraft attached which is a Jack Devine R4 Firecracker. http://www.jackdevinemodels.com/firecracker_r4.htm I opted out and went with a Aeroworks 75cc Extra 260 as I don't really have the time to build the R4 and I also like IMAC aerobatics. I was looking at speeds of 140+ when researching it. I was sold on Supercool's props http://www.supercoolprops.com/price_list2.php He recommended the 18X20F1 that many of the USRA guys run on 100cc engines... that's what he told me anyway. These props are $100. That prop seems to me like it would be about the right size for your 50 but it would be an expensive test. I also attached my prop chart which you probably already have something similar. Looks to me like you hit a wall with it and it's going to take something drastic to get through. Cheers, Lyle

Hey Lyle,

I looked at that same R4... I didn't want to invest a lot of building time in it either. Been there, done that. I do believe I hit a wall with my Sundowner. Even in a full throttle dive I'm only seeing 137.6 MPH. I was very surprized and disappointed at that! I really hoped for 145-150 in a dive... That 18x20F1 prop is way too big for a 50cc unless it was running on a whole lot of nitro.

I just need to clean up the airframe to try to reduce drag as much as I can.

[mfuess]

I have one more prop on the way to test. After that, it is what it is... and I'll fly it whatever it is.

[dptp9lf]

	Quote: Originally Posted by mfuess
	Hey Lyle, I looked at that same R4... I didn't want to invest a lot of building time in it either. Been there, done that. I do believe I hit a wall with my Sundowner. Even in a full throttle dive I'm only seeing 137.6 MPH. I was very surprized and disappointed at that! I really hoped for 145-150 in a dive... That 18x20F1 prop is way too big for a 50cc unless it was running on a whole lot of nitro. I just need to clean up the airframe to try to reduce drag as much as I can.

You hit the nail on the head with the nitro thing... that's what it would take to get it to the next level
Cheers,
Lyle

[Sparky69]

Guys,
The USRA 100cc class has been dead for quite some time. Not even in the rule book. I don't know if the 100cc guys were running nitro or gas but you won't spin that prop with a 50cc engine. now a 80cc on alcohol would be fine.
now why don't you wait for the USRA finalize the rules for the Sundowner for this year make your plane compliant and come race with us?
Also your testing and info seems to raise doubt about the 150 mph electric sundowner doesn't it? Maybe he had a tail wind.
Sparky

[mfuess]

	Quote: Originally Posted by Sparky69
	Guys, The USRA 100cc class has been dead for quite some time. Not even in the rule book. I don't know if the 100cc guys were running nitro or gas but you won't spin that prop with a 50cc engine. now a 80cc on alcohol would be fine. now why don't you wait for the USRA finalize the rules for the Sundowner for this year make your plane compliant and come race with us? Also your testing and info seems to raise doubt about the 150 mph electric sundowner doesn't it? Maybe he had a tail wind. Sparky

We have had (over the years) a "Run what you Brung" class. Basically, an open class to anything that'll turn left. The smaller airplanes had the turn advantage (sometimes) but always fell short on the straights. The Q500's powered with 55AX engines on pipes held their own to just about anything, even today. Lightweight, agile, and fast. However they are butt ugly... and don't resemble any sort of real aircraft.

I suppose it's "possible" to have an electric Sundowner make it up to 150 MPH. But it absolutely positively can not maintain it for the duration of a race. Electrics are subject to the same drag physics we are, in a Sundowner anyway. As you well know it takes a massive amount energy to get a Sundowner up to, and sustain the kind of speeds we are flying at. HOWEVER, put electrics in an F3D and we'll get our butts kicked seven ways to Sunday.

[mfuess]

OK, here's the bottlom line with my BME 50 powered Sundowner. I recorded an actual 145.6 MPH air speed today. It cannot maintain this kind speed in doing pylon laps. It can however, maintain an easy sustained 100+ MPH throughout the course with virtually no speed loss in the turns and I was making high-G approximately 50 foot radius turns. I put a LOT of stress on this aircraft! You could see the wings bending during the turns.

My best performing prop was a BIELA 18x12 Carbon Fiber. While it didn't produce the topend of a high pitch APC, it totally innialated all the APC props in the turns and average lap times. NONE of the APC props could maintain a constant speed in and out of the turns.

Ho how I wished Biela made an 18x14 or 16...

Anyway, I am very pleased with the Sundowners performance today. I just ordered a FULL LENGTH Tuned Pipe for the BME. This should add another 1000 RPM to my baseline...

[CRG]

A sustained 100+mph (whatever that is) over what length course? We're seeing that with EVO 35 and Saito powered Sundowners, with APC props, no pipes, and a lot less effort.

For all the work you seem to be doing you should get yourself an F1 and come race with us. 150mph out of the box on a stock GT80 and tons of fun.

CG.

	Quote: Originally Posted by mfuess
	OK, here's the bottlom line with my BME 50 powered Sundowner. I recorded an actual 145.6 MPH air speed today. It cannot maintain this kind speed in doing pylon laps. It can however, maintain an easy sustained 100+ MPH throughout the course with virtually no speed loss in the turns and I was making high-G approximately 50 foot radius turns. I put a LOT of stress on this aircraft! You could see the wings bending during the turns. My best performing prop was a BIELA 18x12 Carbon Fiber. While it didn't produce the topend of a high pitch APC, it totally innialated all the APC props in the turns and average lap times. NONE of the APC props could maintain a constant speed in and out of the turns. Ho how I wished Biela made an 18x14 or 16... Anyway, I am very pleased with the Sundowners performance today. I just ordered a FULL LENGTH Tuned Pipe for the BME. This should add another 1000 RPM to my baseline...

[mfuess]

I may have to seriously consider that. I've invested a lot of time & money into the Sundowner...