Sundowner 50 Arf
09-30-2008, 03:38 PM
#426
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RE: Sundowner 50 Arf
The covering of the inlet does work. It increases the vacuum and allows more air to run by the motor and exit at a higher rate, rather then creating turbulence within the cowl.
10-05-2008, 08:33 AM
#427
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RE: Sundowner 50 Arf
I flew my Sundowner yesturday with a YS 110 on 30%Nitro and a 14x14N apc cut to 12" Awsome ...
Until the fire wall ripped off [:-]
I have now glassed it and installed my data system so I can post some speed data.
I have foud the Flaperons help quite alot on landings, I programed them so I have 7/16 of alerion deflection remainig when the flaps are fully down and I also have 48% up trim to compensate.
Also when in high rates (as in the manual) at high speed if you bank and yank it will tip stall but it is fine in low rates.
I am using the stock CG and it seems fine maybe 1/2 oz on the tail would work.
I started with 35 % expo on high and low rates and soon removed all expo on the low rates
Until the fire wall ripped off [:-]
I have now glassed it and installed my data system so I can post some speed data.
I have foud the Flaperons help quite alot on landings, I programed them so I have 7/16 of alerion deflection remainig when the flaps are fully down and I also have 48% up trim to compensate.
Also when in high rates (as in the manual) at high speed if you bank and yank it will tip stall but it is fine in low rates.
I am using the stock CG and it seems fine maybe 1/2 oz on the tail would work.
I started with 35 % expo on high and low rates and soon removed all expo on the low rates
10-06-2008, 11:20 PM
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RE: Sundowner 50 Arf
Finally happened. Slowed down too much on downwind, turned on base and pulled too much elevator and it tip stalled. I was able to recover, but ran out of airspace. It landed hard on mains and the gear pivoted back and slashed though the fuselage. Wheel pant punched hole in left wing. Fortunately the .55ax and radio gear is fine. I learned my lesson the hard way about using nylon bolts instead of metal screws on landing gear. I think I dialed back the throttle trim too much as well. I had fun with the Sundowner in the two dozen flights I had with her. Got a little bored doing low level high speed passes though. I think I'll stick with my 3D Twist 40. Going to put the .55ax in a Pulse XT 40 which should really haul the mail. I'm selling the canopy with pilot helmet and right wing with wing tube on ebay if anyone is interested. Might list the right wing as well, hole is easily repairable.
10-07-2008, 10:36 AM
#430
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RE: Sundowner 50 Arf
ORIGINAL: mongo2
I flew my Sundowner yesturday with a YS 110 on 30%Nitro and a 14x14N apc cut to 12" Awsome ...
Until the fire wall ripped off [:-]
I have now glassed it and installed my data system so I can post some speed data.
I have foud the Flaperons help quite alot on landings, I programed them so I have 7/16 of alerion deflection remainig when the flaps are fully down and I also have 48% up trim to compensate.
Also when in high rates (as in the manual) at high speed if you bank and yank it will tip stall but it is fine in low rates.
I am using the stock CG and it seems fine maybe 1/2 oz on the tail would work.
I started with 35 % expo on high and low rates and soon removed all expo on the low rates
I flew my Sundowner yesturday with a YS 110 on 30%Nitro and a 14x14N apc cut to 12" Awsome ...
Until the fire wall ripped off [:-]
I have now glassed it and installed my data system so I can post some speed data.
I have foud the Flaperons help quite alot on landings, I programed them so I have 7/16 of alerion deflection remainig when the flaps are fully down and I also have 48% up trim to compensate.
Also when in high rates (as in the manual) at high speed if you bank and yank it will tip stall but it is fine in low rates.
I am using the stock CG and it seems fine maybe 1/2 oz on the tail would work.
I started with 35 % expo on high and low rates and soon removed all expo on the low rates
Mongo!
Hey buddy. Perhaps my pain will result in your success.
A few posts ago in this thread I put up a letter that Jett sent to me regarding SD firewalls. It's a good short read. I hope your repair went well and glad you were able to save it. I've not yet flown my little SD but I'm on my 3rd (hate admitting that) big 80"er.
Here's what I've learned.
If the CG is anything close to being "back" this pig will snap like a dry twig when you get "kinky" with the elevator. The powers that be (meaning anyone cause I still consider myself to be a newb) all strongly recommend that the CG be well forward of what the manual suggests. Since the little SD is just a smaller version of the big one, I'm making the assumption that flight characteristics are not all that dissimilar. Running on that assumption I suggest you move the CG forward of what the manual says and be very careful with your inputs (close to the ground anyways) until you have a very good understanding on how this little biche is going to respond.
Here's a sample of what a low altitude full elevator, full throttle snap looks like with the 80" SD. I don't wish it upon anyone. Man, did it make a cool ass "whump" when it hit the ground though. Was quite graphic. You know its a good one when the lens on the camera doesn't have a wide enough angle to capture all the parts. The engine went about another 40 feet with a "blood trail" of confetti behind it.
All the best.
C
10-07-2008, 01:44 PM
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RE: Sundowner 50 Arf
Wow, you really augered that one in. I think it's safe to say that both small and large SD's are prone to snapping with excessive elevator input. We both learned the hard way...
10-07-2008, 02:17 PM
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RE: Sundowner 50 Arf
nesikachad,
I agree on the CG, my plane no longer exsits after a fuel line came off and I had to land (stall...) in a soybean feild.
I noticed that the elevator is slightly tirmed down for level flight showing the CG is to far back.
I did hit 141 in a dive I would say around 130-135 level with 3.5" wheeels and no wheel pants.
Also I picked up 5mph by taping off the extra cooling intakes.
here is some data:
I agree on the CG, my plane no longer exsits after a fuel line came off and I had to land (stall...) in a soybean feild.
I noticed that the elevator is slightly tirmed down for level flight showing the CG is to far back.
I did hit 141 in a dive I would say around 130-135 level with 3.5" wheeels and no wheel pants.
Also I picked up 5mph by taping off the extra cooling intakes.
here is some data:
10-07-2008, 11:41 PM
#433
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RE: Sundowner 50 Arf
What do you guys think. Im running a 13x9 on a OS 91 surpass 4 stroke. Its ok but should be faster. I was flying with a midget mustang that overall was a bigger plane than the downer. It had a 61 evo 2 stroke and could out accelerate me everytime. But if I stayed into the throttle I would slowly pass. Think a 12x11 would be that big a difference?
10-08-2008, 05:49 PM
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RE: Sundowner 50 Arf
I dont know what rpm you are at , so I guesed
if you turn 9700rpm with a 13x9 that = 82mph
10100 (same power output) 12x11 = 105.2mph
Pitch is in inches meaning for every revolution the prop moves 11"
or
11" pitch x 10100rpm= 111100
X 60 (inches per hour)6666000
/ 12 (inches to feet)=555500
/ 5280 (feet to miles)= 105.2
I have an easy spread sheet I could give you
if you turn 9700rpm with a 13x9 that = 82mph
10100 (same power output) 12x11 = 105.2mph
Pitch is in inches meaning for every revolution the prop moves 11"
or
11" pitch x 10100rpm= 111100
X 60 (inches per hour)6666000
/ 12 (inches to feet)=555500
/ 5280 (feet to miles)= 105.2
I have an easy spread sheet I could give you
10-09-2008, 04:08 AM
#435
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RE: Sundowner 50 Arf
Thanks mongo. Im turning 9,500 on the ground with the 13x9. I dont think Im getting anywhere near 80mph though. Im thinkin 60 to maybe 70 mph. I know thats a wide range but I "feel" its somewhere in there. If I could pick up the proposed 20mph by dropping to a 12x11 I know it would feel quite a bit faster. Even if im only truely hitting 85. The thing runs great. Im afraid to tune anymore. You can idle all day then jam right to full and no probs. Although Im wondering if that slimline muffler I have on it is hurting some of its grunt. Perhaps llosing back presure with the 2 outlets. One of these days Ill plug one up and see.
Im starting to like this plane. I didnt at first. If I cut the throttle a lil I can do nice rolls. If I try em full throttle it kinda snaps through em. It doesnt like to track well in loops. Im fairly certain the lateral balance is a little off. One big plus of this plane is the grey cote on the tips under the wings. They really stand out for some reason.
Now how much time are we talking here in relation to going to higher pitched props and acceleration. Is there a general rule saying how long it should take to reach that top speed?
Im starting to like this plane. I didnt at first. If I cut the throttle a lil I can do nice rolls. If I try em full throttle it kinda snaps through em. It doesnt like to track well in loops. Im fairly certain the lateral balance is a little off. One big plus of this plane is the grey cote on the tips under the wings. They really stand out for some reason.
Now how much time are we talking here in relation to going to higher pitched props and acceleration. Is there a general rule saying how long it should take to reach that top speed?
10-09-2008, 04:26 PM
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RE: Sundowner 50 Arf
Erik,
On a four stroke engine you dont want back pressure, a properly designed header system will actualy aid in removing the exhaust gasses (also known as scavenge effect)
You can see acceleration in the graph I posted
Put a YS 110 in her you will not be sorry...
135mph level 141 in a dive with 3.5 inch wheels and now wheel pants should see 140 when finished
On a four stroke engine you dont want back pressure, a properly designed header system will actualy aid in removing the exhaust gasses (also known as scavenge effect)
You can see acceleration in the graph I posted
Put a YS 110 in her you will not be sorry...
135mph level 141 in a dive with 3.5 inch wheels and now wheel pants should see 140 when finished
10-09-2008, 11:30 PM
#437
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RE: Sundowner 50 Arf
I know all about scavenging exhaust from my Camaro. I just cant imagine a single cylinder with 2 big outlets is helping much. I dunno. Im still turning the same peak rpms on the ground that I did with the stock muffler. But it may be taking a hit lower in the rpm range. And I have a YS110 and cosmic minnow waiting to be put together. I wouldnt dare try it on the lil downer. I can barely see it as it is. That thing with a YS would disappear in no time. That minnow better get over 100mph.
10-10-2008, 11:55 PM
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RE: Sundowner 50 Arf
Just out of curiosity guys, with the Jett60, YS110, and the OS91 class of engines, what's used as far as servos on the control surfaces? Are the recommended JR 821 digitals enough?
10-15-2008, 08:27 AM
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RE: Sundowner 50 Arf
Bob
Your coments are a breath of fresh air, I read a lot of articles on the forums about larger engines being installed, I put a used TT Pro 46 with Magnum pitts muffler (no holes in cowl) in my SD and was very happy with the weight and flying caracteristics, one of our members has the Revolver with a 55 AX in it and their is very little between the models. Taking the lighter is better concept, I am now fitting a TT Redline 53 Heli engine 13.4 oz with a quoted HP of 2.1 at 17000 rpm, plan on starting on a 11.3 x 8.4 prop, just looking to work out a suitable pipe/muffler to fit, I will post some photos and flight details this weekend. I always wonder when these big engines are installed, what height above sea level they are at.
Noddy
Your coments are a breath of fresh air, I read a lot of articles on the forums about larger engines being installed, I put a used TT Pro 46 with Magnum pitts muffler (no holes in cowl) in my SD and was very happy with the weight and flying caracteristics, one of our members has the Revolver with a 55 AX in it and their is very little between the models. Taking the lighter is better concept, I am now fitting a TT Redline 53 Heli engine 13.4 oz with a quoted HP of 2.1 at 17000 rpm, plan on starting on a 11.3 x 8.4 prop, just looking to work out a suitable pipe/muffler to fit, I will post some photos and flight details this weekend. I always wonder when these big engines are installed, what height above sea level they are at.
Noddy
ORIGINAL: nesikachad
Man, all you guys SUCK.
I'm stuck in Baghdad and I can't wait to get home to get started on this model. I bought it last spring and just ran out of time with other projects. I have an OS90 for it but after reading this entire thread decided perhaps there's better options. I've contacted Jett and I'm going with the 60. Bob Brassell wrote me a very informative/helpful and down to earth letter about this little thrasher. Here is what he says:
Chad,
Thanks for writing.....
Dub is still recovering a bit from Hurricane Ike that messed up most of Houston about a week ago. Allow me to help with your questions.
First off........
My personal thanks for your service over in Iraq and for providing protection to the Embassy.
About the Sundowner.......
There is only so much you can do with an ARF. It is a big plane, flys well, and it is relatively quick..... but it is not really designed for all-out speed. The plane has lots of frontal area. Bigger engines (weight) or more drag on it will not help.
The semi-internal muffler setup that was developed is about the cleanest, quickest setup anyone has found for the plane. You can use a regular Jett SJ-50 or the SJ-60LX and get an easy 120+ mph out of it. For most, they get a bit more. The 50 and 60LX are "40" size engines, so the engine and muffler both fit well in the aircraft.
Adding a full size pipe to either engines will gain you some power, and maybe 300-500 rpm on say a 9x8 prop - but it will also add weight and complexity of trying to route the pipe. You would have to do several aircraft mods, configure the engine position, and select/make a suitable header for the installation (Jett does not fabricate most of the headers). In the end, you gain MAYBE 1 or 2 mph on the top end. So ask your self if it is worth the hassle to go from 130 mph to 132 mph ?
Several folks are flying the OS46FX, OS46AX, TT46pro, Webra 55 and OS55AX in the plane using the Jett-Stream muffler and the same internal muffler setup. All are very happy. The one OS46FX/Jett combo I flew a few months ago was easily over 100 mph and it ran and sounded great.
You will notice that most of the folks who try cramming an OS91 or something like that in the Sundowner are not going any faster than the 130ish range Dub and Mike came up with on their Jett 60LX powered sundowner (as on the web site). Even the few folks who tried to put the Jett 90L engine up front didn't end up with any more speed.
Funny you mentioned firewall ripping. You can do that with an OS25 the way the Sundowner is built. That is the main modification you have to do with ANY engine on the Sundowner - get inside of the firewall box and add triangle stock. Most have also fiberglassed over the outside of the engine box.
Retracts are not an option on this plane. There is no practical location to install them. The wing and fuselage structure could not accommodate any useful retract installation without a lot of re-work. And without adding gear doors, the resulting added structure, weight impact and wheel well turbulence would not gain you much in speed. Again, is it worth the hassle for 1 mph ?
The Sundowner 50 is a nice plane, and it can be quick, but accept it for what it is.... and take what it is willing to give.
Sure, if you were building the Sundowner 50 from a kit, making modifications to accommodate a FIRE 60LX with a full pipe as you were building it would be fairly easy - built in pipe tunnel, riser header, rearrange the radio, tank and wing installation ..... that would be the ultimate. But if you live in an ARF world..... you live with the limitations.
If you want something smooth, fast, retracts, and a Jett 60LX up front ...... look at www.junorc.com and consider the Tsunami .40 one heck of a nice aircraft, it flys like its on rails, and is a very well crafted kit. The F-20 is also a great choice.
I hope this is helpful.
Regards,
Bob Brassell
Man, all you guys SUCK.
I'm stuck in Baghdad and I can't wait to get home to get started on this model. I bought it last spring and just ran out of time with other projects. I have an OS90 for it but after reading this entire thread decided perhaps there's better options. I've contacted Jett and I'm going with the 60. Bob Brassell wrote me a very informative/helpful and down to earth letter about this little thrasher. Here is what he says:
Chad,
Thanks for writing.....
Dub is still recovering a bit from Hurricane Ike that messed up most of Houston about a week ago. Allow me to help with your questions.
First off........
My personal thanks for your service over in Iraq and for providing protection to the Embassy.
About the Sundowner.......
There is only so much you can do with an ARF. It is a big plane, flys well, and it is relatively quick..... but it is not really designed for all-out speed. The plane has lots of frontal area. Bigger engines (weight) or more drag on it will not help.
The semi-internal muffler setup that was developed is about the cleanest, quickest setup anyone has found for the plane. You can use a regular Jett SJ-50 or the SJ-60LX and get an easy 120+ mph out of it. For most, they get a bit more. The 50 and 60LX are "40" size engines, so the engine and muffler both fit well in the aircraft.
Adding a full size pipe to either engines will gain you some power, and maybe 300-500 rpm on say a 9x8 prop - but it will also add weight and complexity of trying to route the pipe. You would have to do several aircraft mods, configure the engine position, and select/make a suitable header for the installation (Jett does not fabricate most of the headers). In the end, you gain MAYBE 1 or 2 mph on the top end. So ask your self if it is worth the hassle to go from 130 mph to 132 mph ?
Several folks are flying the OS46FX, OS46AX, TT46pro, Webra 55 and OS55AX in the plane using the Jett-Stream muffler and the same internal muffler setup. All are very happy. The one OS46FX/Jett combo I flew a few months ago was easily over 100 mph and it ran and sounded great.
You will notice that most of the folks who try cramming an OS91 or something like that in the Sundowner are not going any faster than the 130ish range Dub and Mike came up with on their Jett 60LX powered sundowner (as on the web site). Even the few folks who tried to put the Jett 90L engine up front didn't end up with any more speed.
Funny you mentioned firewall ripping. You can do that with an OS25 the way the Sundowner is built. That is the main modification you have to do with ANY engine on the Sundowner - get inside of the firewall box and add triangle stock. Most have also fiberglassed over the outside of the engine box.
Retracts are not an option on this plane. There is no practical location to install them. The wing and fuselage structure could not accommodate any useful retract installation without a lot of re-work. And without adding gear doors, the resulting added structure, weight impact and wheel well turbulence would not gain you much in speed. Again, is it worth the hassle for 1 mph ?
The Sundowner 50 is a nice plane, and it can be quick, but accept it for what it is.... and take what it is willing to give.
Sure, if you were building the Sundowner 50 from a kit, making modifications to accommodate a FIRE 60LX with a full pipe as you were building it would be fairly easy - built in pipe tunnel, riser header, rearrange the radio, tank and wing installation ..... that would be the ultimate. But if you live in an ARF world..... you live with the limitations.
If you want something smooth, fast, retracts, and a Jett 60LX up front ...... look at www.junorc.com and consider the Tsunami .40 one heck of a nice aircraft, it flys like its on rails, and is a very well crafted kit. The F-20 is also a great choice.
I hope this is helpful.
Regards,
Bob Brassell
10-16-2008, 03:24 AM
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RE: Sundowner 50 Arf
Similar results with mine - can't get what I'd call fast with the 13" props on the OS 91 FS. I'll try 12" range next, but will have to cut the motor to land, as even idling it goes forever.
Cam
Cam
10-17-2008, 06:52 PM
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RE: Sundowner 50 Arf
Has anyone ever messed with trying a mousse can type muffler set up on the sundowner with a os 60 or a towerhobbies .75 engine, the moussecan mufflers seem to make great horsepower,,
10-17-2008, 08:52 PM
#444
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RE: Sundowner 50 Arf
ORIGINAL: camdyson
Similar results with mine - can't get what I'd call fast with the 13" props on the OS 91 FS. I'll try 12" range next, but will have to cut the motor to land, as even idling it goes forever.
Cam
Similar results with mine - can't get what I'd call fast with the 13" props on the OS 91 FS. I'll try 12" range next, but will have to cut the motor to land, as even idling it goes forever.
Cam
prob would suck. I think the plane is a little heavy as I put a 6v pack behind the wing and that makes for a nice even descent. There is no flare with this plane I just ride the elevator until touchdown. Once I got use to it I dont mind the fast landings at all. The damn thing is hell to taxi though. Any bumps mixed with a cross wind and the things chopping the prop. I also put a slimline pitts style muffler on it. Seems to have lost some low end grunt but the tach still reads 9500 wide open on the ground.
10-24-2008, 07:10 AM
#445
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RE: Sundowner 50 Arf
Here's some pictures of my SD, engine is a Thunder Tiger Redline 53 Heli engine with a pipe and manifold of a thunder tiger Hammer 50 off road car, run up tests on the ground so far are 12500 RPM on a 11.3 x 8.2 TT prop, they quote 2.1 BHP for this engine. This combo weighs the same as the first engine and standard muffler. a TT 46 Pro, which flew quite well, the big plus is everything fits in the cowl, I had to cover the holes under the tank and in the former behind the under cart block. Will let you know how it goes on Sunday.
Noddy
Noddy
10-24-2008, 10:06 AM
#446
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RE: Sundowner 50 Arf
Nice to see some creativity !! Awaiting to hear how it flys.....!
The 2.1 rating is up around 17,000 rpm ..... its ported to turn up. A bit different prop selection will help you a bunch here (unless you are trying to hit a sound limit target)
The 2.1 rating is up around 17,000 rpm ..... its ported to turn up. A bit different prop selection will help you a bunch here (unless you are trying to hit a sound limit target)
10-26-2008, 08:21 AM
#447
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RE: Sundowner 50 Arf
Hi Bob
Thanks for the encouragement, got a couple of flights in today with 2 different size props 11.3 x 6.5 and 11.3 x 8.2, I was using 10% mix and we tached up 12000 on both props, in flight the 6.5 felt better, especially in any up manouvers, I will try some APC props next week, the 12000 on both props has me a bit puzled, I think the pipe or the header may be restricting the RPM, I did note that the header port was smaller than the engine exhaust outlet, but from what I saw there is no room to open it up, I might machine a 1/4 inch spacer to flow from the engine to the header. I also did not have the spinner on today as I was waiting for a thru nut as the Heli crank is about 1/4 inch shorter than a std 46.
Overall I am very happy with the result, I figure that 12000 on the 8.2 allowing for 10% slipage would give me about 98 MPH. The next project is to attach a set of floatsto the SD for our next float meet, as well as being challenged to redisign the hull on a Seawind to take off strait with no porpoising, but thats for anothew forum, however one of these engines might find its way into the Seawind, still on the theory of lighter flys better.
Noddy
Thanks for the encouragement, got a couple of flights in today with 2 different size props 11.3 x 6.5 and 11.3 x 8.2, I was using 10% mix and we tached up 12000 on both props, in flight the 6.5 felt better, especially in any up manouvers, I will try some APC props next week, the 12000 on both props has me a bit puzled, I think the pipe or the header may be restricting the RPM, I did note that the header port was smaller than the engine exhaust outlet, but from what I saw there is no room to open it up, I might machine a 1/4 inch spacer to flow from the engine to the header. I also did not have the spinner on today as I was waiting for a thru nut as the Heli crank is about 1/4 inch shorter than a std 46.
Overall I am very happy with the result, I figure that 12000 on the 8.2 allowing for 10% slipage would give me about 98 MPH. The next project is to attach a set of floatsto the SD for our next float meet, as well as being challenged to redisign the hull on a Seawind to take off strait with no porpoising, but thats for anothew forum, however one of these engines might find its way into the Seawind, still on the theory of lighter flys better.
Noddy
11-08-2008, 11:59 AM
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RE: Sundowner 50 Arf
Ok. I've flown 3 flights with my SD50. 2 with JEN .57 and one with 55AX. Reason for that engine change was that JEN .57 doesn't rev more than 12570 with APC 10x9 on vertical dive! Logged 13740 for 55AX with APC 10x10 on 45degree dive. I didn't get max speed out of my logger because I had wrong settings on it. It cut the graph on 199KPH. There were 7 passes where speed graph was on 199KMH, thats 123.68MPH
11-09-2008, 02:06 PM
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RE: Sundowner 50 Arf
Maybe I should take the airfilter off of my 55AX. It might gain some RPM without it... I put the filter on when the engine was on my pusher plane...
11-11-2008, 12:00 PM
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RE: Sundowner 50 Arf
Ok... I threw the Perry pump away and switched to smaller pitch props. Engine temp came down about 40C... Here are couple of graphs from todays flights. First is with APC10x9 and second with APC11x7. Engine is 55AX with 20% nitro and 20% Klotz KL-198 HeliGlow. Oh and the airfilter is gone.
Again all the top speeds were on 45deg dive
Again all the top speeds were on 45deg dive