RE: H9 Sundowner  
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RE: H9 Sundowner - 1/28/2008 10:02:51 PM   
Boo2


 

Posts: 160
Joined: 11/21/2004
From: Brighton, UNITED KINGDOM
Status: offline 		Hi,

Has anyone fitted a pipe tunnel to the Sundowner F1 ? I'm thinking of buying one as a first gasser and using either a ZDZ 40-RE FAI or else an MVVS (Evolution) 45 MG. Either of these should weigh about the same as the evolution 35 or even a bit less.

Pix would be nice if anyone has done this, or else pix of the inside of the fuse to show whether or not it's possible.

Thanks,

Boo

(in reply to Rebellion)
       Post #: 601

RE: H9 Sundowner - 1/28/2008 10:08:41 PM   
Boo2


 

Posts: 160
Joined: 11/21/2004
From: Brighton, UNITED KINGDOM
Status: offline 		Hi,

I seem to have confused myself about converting prop rpm / pitch into plane speed in mph. Am I right in saying the prop pitch speed im mph is rpm * pitch * 60 / (12 * 3 * 1760) ?

My reason for asking is people are talking about speeds of 135 mph when the figures don't add up. Eg :

10,000 rpm * 12" pitch * 60 / (12 * 3 * 1760) = 113 mph.

Assuming 10k is the very highest the Evo35 will run and 12" is the pitch often quoted for the prop tne this is a lot less than the speeds I've seen quoted and there should really be a further fact or .8 applied for prop slip reducing the figure further to 90 mph.

Am I doing something wroing here or what ?

Thanks,

Boo

(in reply to Boo2)
       Post #: 602

RE: H9 Sundowner - 1/29/2008 4:27:55 PM   
PJ_TankPilot



Posts: 393
Joined: 1/16/2002
From: Phoenix, AZ, USA
Status: offline
quote:

ORIGINAL: Boo2
Am I doing something wroing here or what ?

Speeds posted are often optimistic.

‘Measured’ (radar gun or stopwatch) speeds are often downhill or with a tail wind.

The only way I know of to measure air speed accurately is with an onboard device.



< Message edited by PJ_TankPilot -- 1/29/2008 5:09:36 PM >

_____________________________

Warbird racing exercises your adrenal glands.
PJ Herman

(in reply to Boo2)
       Post #: 603

RE: H9 Sundowner - 1/30/2008 10:43:47 AM   
Boo2


 

Posts: 160
Joined: 11/21/2004
From: Brighton, UNITED KINGDOM
Status: offline
quote:

ORIGINAL: PJ_TankPilot

quote:

ORIGINAL: Boo2
Am I doing something wroing here or what ?

Speeds posted are often optimistic.


So I'm right in thinking that the ZDZ turning a 20x12 prop at 6900 rpm will have a pitch speed of just under 80 mph ? And to get a pitch speed of 130 at 7500 rpm requires an 18" pitch prop ? If so then can anyone tell me what diameter prop I will need for the ZDZ to turn at 7500 rpm given 18" of pitch, and where I can get one ? Or is 130 mph just not reasonable with this combo ?

Thanks,

Boo

(in reply to PJ_TankPilot)
       Post #: 604

RE: H9 Sundowner - 1/30/2008 1:35:57 PM   
PJ_TankPilot



Posts: 393
Joined: 1/16/2002
From: Phoenix, AZ, USA
Status: offline 		I wish it was that simple but there are too many variables.

RPM in the air will be different than RPM on the ground.

The pitch of props varies from center to tip. The effective pitch may be different than that specified by the manufacturer.

The effective pitch will vary depending on speed and RPM.

There are cases where you can increase the pitch AND RPM and decrease speed.

However, you should get within 20% using your calculation.

Plus or minus 20% is huge so my advice is try different props and try to measure speed.



_____________________________

Warbird racing exercises your adrenal glands.
PJ Herman

(in reply to Boo2)
       Post #: 605

RE: H9 Sundowner - 2/1/2008 1:02:00 PM   
mfuess



Posts: 402
Joined: 9/5/2002
From: Bedford, TX, USA
Status: offline
quote:

ORIGINAL: Boo2

Hi,

Has anyone fitted a pipe tunnel to the Sundowner F1 ? I'm thinking of buying one as a first gasser and using either a ZDZ 40-RE FAI or else an MVVS (Evolution) 45 MG. Either of these should weigh about the same as the evolution 35 or even a bit less.

Pix would be nice if anyone has done this, or else pix of the inside of the fuse to show whether or not it's possible.

Thanks,

Boo


An Evolution 45 would be a good choice. It's light weight and surprizingly powerful. You can install a Tuned Pipe if you like. I have a BME 50 in my Sundowner and its on a Tuned Pipe. My Sundowner flies like a dream! The ONLY reason I didn't go with the Evo 45 is, the stand-off distance required for the 45. I didn't feel like cutting the stand-off box on the Sundowner to make the 45 fit properly. My BME powered Sundowner can maintain 137 MPH laps, and high-bank turn up to 152.7 Miles Per Hour. I use a Flight Data Recorder...

If you do happen to go with the (MVVS/Evo) 45 you'll like it, except for the Ignition Module. It takes a minimum of 6.4 volts to operate.



As you can see, my BME 50 fits without firewall mods. It just needed beefing up.

(in reply to Boo2)
       Post #: 606

RE: H9 Sundowner - 2/5/2008 10:45:34 PM   
Boo2


 

Posts: 160
Joined: 11/21/2004
From: Brighton, UNITED KINGDOM
Status: offline
quote:

ORIGINAL: mfuess
An Evolution 45 would be a good choice. It's light weight and surprizingly powerful. You can install a Tuned Pipe if you like. I have a BME 50 in my Sundowner and its on a Tuned Pipe. My Sundowner flies like a dream! The ONLY reason I didn't go with the Evo 45 is, the stand-off distance required for the 45. I didn't feel like cutting the stand-off box on the Sundowner to make the 45 fit properly.


Hi mfuess, thanks for the reply. From what you are saying, I think you mean the the Evo / MVVS 45 is quite long from front to back and needs short standoff mounts and a hole in the box to accomodate the carb ? I can do that easily enough, but I don't really want to get into any tricky mods of the front of the plane.

As you know, the Evo and ZDF are both rear exhaust. I intend to mount the engine inverted, can you tell me whether it is viable to fit a cannister or else a pipe tunnel into the Sundowner fuselage without too much trouble ? I will need a custom swan-neck header but think I can find one.

quote:

ORIGINAL: mfuess
My BME powered Sundowner can maintain 137 MPH laps, and high-bank turn up to 152.7 Miles Per Hour. I use a Flight Data Recorder...


Sounds like the business, what rpm do you get with the BME and what prop are you using ? I have a hiking gps I could use tp measure the speed - this'll be the first plane I own that could easily stand the weight.

quote:

ORIGINAL: mfuess
If you do happen to go with the (MVVS/Evo) 45 you'll like it, except for the Ignition Module. It takes a minimum of 6.4 volts to operate.


Well in that case I think I will use a 2-cell lipo.

Thanks again,

--
Boo

(in reply to mfuess)
       Post #: 607

RE: H9 Sundowner - 2/6/2008 5:34:14 AM   
kochj



Posts: 1396
Joined: 12/5/2005
From: Victoria, MN, USA
Status: offline 		That plane with those mid sized gassers looks like lota fun!....

BOO2,
A ZDZ 40F3A, actually weights the same as the EVO 26gt.....

How has the plane held up to the larger engines?
How many flights on the 40cc+ engines?

Anyone thought about placing a SAito 36G Gas engine in this one?

I love to race planes. Perhaps someone should put together a event that has sundowners w/ a run what you brung class?
Is the worry that planes will be crashing all over the place, due to overpowered aircrafts?

How about the unlimited class? those airframes have been overpowered, with NO guarantee that they are SAFE to fly!////

I don't see any reason why a open class for Sundowners, wouldn't be a great way to include more planes in Pylon racing....




_____________________________

Winning isn''t everything, it''s all there is.

(in reply to mfuess)
       Post #: 608

RE: H9 Sundowner - 2/6/2008 6:24:57 AM   
sskianpour


 

Posts: 13
Joined: 3/15/2006
From: highlands ranch, CO, USA
Status: offline 		Kochj I agree completely. I have just finished installing my DA-50 on my Downer and she looks like shes gonna honk! Put some Carbon Fiber landing gear from GraphTech on her and that gives me 2 more inches of clearance which should be plenty for that 20 X12 or 20 X 14 prop!

I am sorry I have spaced on the photos everyone, but probably this weekend or next at the latest I will post some. Unlimited Sundowner class...drool....what a great idea!

(in reply to kochj)
       Post #: 609

RE: H9 Sundowner - 2/6/2008 6:58:17 AM   
CRG


 

Posts: 104
Joined: 6/1/2005
From: , CA, USA
Status: offline
The Saito gasoline four stroke engine might be nice in the Sundowner, certainly economical. Might take a little work to balance it.

In my opinion you are WAY off the mark with your comment about the Unlimited airframes. They are built with race speeds and loads in mind, which are well over 200mph and 20 plus G's. They are required to be inspected prior to being permitted to race, and get inspected at each race event. There are requirements for batteries, servos, control linkages, maximum engine weight and more. Not even close to just jamming more motor into an ARF. Typical Unlimiteds these days are using motors of between 150 and 290cc, the faster airplanes are around 240mph in the straights.

Craig.


quote:

ORIGINAL: kochj

That plane with those mid sized gassers looks like lota fun!....


BOO2,
A ZDZ 40F3A, actually weights the same as the EVO 26gt.....

How has the plane held up to the larger engines?
How many flights on the 40cc+ engines?

Anyone thought about placing a SAito 36G Gas engine in this one?

I love to race planes. Perhaps someone should put together a event that has sundowners w/ a run what you brung class?
Is the worry that planes will be crashing all over the place, due to overpowered aircrafts?

How about the unlimited class? those airframes have been overpowered, with NO guarantee that they are SAFE to fly!////

I don't see any reason why a open class for Sundowners, wouldn't be a great way to include more planes in Pylon racing....





(in reply to kochj)
       Post #: 610

RE: H9 Sundowner - 2/6/2008 4:11:13 PM   
kochj



Posts: 1396
Joined: 12/5/2005
From: Victoria, MN, USA
Status: offline 		CRG,

I undestand that they are inspected for those things that you have mentioned!

But, NO one takes them aside and says "Where are your build photos?"
"I want to see the Intirnals of the that wing and how you used the material"
" I also want to see the CAD drawings and the Load Barrings that a engineer had figured"

My point of my previous commnet was not to Digrade those that have taken time to build a plane for all
out speed and high g's, but to place the engines choice
in the hands of the owners and have it be there responsibility to reinforce what
needs to be to make it safe to fly with the engine of choice!

Perhaps limit the engine to a max 50cc's?

I am sure that there are a few good builders, that can suggest a few mods to make the plane wistand huge G' forces.
Perhaps this plane can already take a 50cc gas engine WOT and then bank hard with no wing
mods other than harwere upgrades and hing sealing? OR it may disinigrate! I do not know.....

This is all irrelivent though, as I am not some AMA official and do not have any kind ot legitimacy of these coments........

I would however, like to put the fun back into the sport of pylon racing..... But not on the expence of Safety....



bY THE WAY,
The BME 50cc with the tuned pipe looks fantastic!!!!

I would think that at least the Sundowner class sould allow the use of a Tuned pipe!!
It would make it that more interesting!

Justin
Justin

< Message edited by kochj -- 2/6/2008 4:18:30 PM >

_____________________________

Winning isn''t everything, it''s all there is.

(in reply to CRG)
       Post #: 611

RE: H9 Sundowner - 2/6/2008 11:53:08 PM   
CRG


 

Posts: 104
Joined: 6/1/2005
From: , CA, USA
Status: offline 		Justin,

The owner/pilot is required to be able to answer questions about how the aircraft is built, and that it uses appropriate materials and techniques. These are not just some thrown together models with ever larger motors put in them. On most of the models the internal structure is visible, and it is checked with the wing off during every pre-race inspection. If an inspector needs to see more they will ask the owner to remove panels as necessary. Models are inspected again if any damage is sustained. Wings have appropriately sized spars and shear webs, skins are laid on a bias for torsional strength etc. Wings have been static loaded to check integrity. The engine choice is in the hands of the owners up to a limit- max. weight for Unlimited, capacity limit for the other classes. Safety is NOT compromised for the sake of all out speed.

The USRA has some desire to maintain the scale portion of racing. The full size Sundowner did not have a two foot diameter pipe down the fuselage.... Pipes are permitted in Unlimited but they have to be internal. Any other organization or club that wants to run Sundowner races can obviously do as they choose.

Craig.

quote:

ORIGINAL: kochj

CRG,

I undestand that they are inspected for those things that you have mentioned!

But, NO one takes them aside and says "Where are your build photos?"
"I want to see the Intirnals of the that wing and how you used the material"
" I also want to see the CAD drawings and the Load Barrings that a engineer had figured"

My point of my previous commnet was not to Digrade those that have taken time to build a plane for all
out speed and high g's, but to place the engines choice
in the hands of the owners and have it be there responsibility to reinforce what
needs to be to make it safe to fly with the engine of choice!

Perhaps limit the engine to a max 50cc's?

I am sure that there are a few good builders, that can suggest a few mods to make the plane wistand huge G' forces.
Perhaps this plane can already take a 50cc gas engine WOT and then bank hard with no wing
mods other than harwere upgrades and hing sealing? OR it may disinigrate! I do not know.....

This is all irrelivent though, as I am not some AMA official and do not have any kind ot legitimacy of these coments........

I would however, like to put the fun back into the sport of pylon racing..... But not on the expence of Safety....



bY THE WAY,
The BME 50cc with the tuned pipe looks fantastic!!!!

I would think that at least the Sundowner class sould allow the use of a Tuned pipe!!
It would make it that more interesting!

Justin
Justin


(in reply to kochj)
       Post #: 612

RE: H9 Sundowner - 2/6/2008 11:57:10 PM   
CRG


 

Posts: 104
Joined: 6/1/2005
From: , CA, USA
Status: offline 		For reference: A broken in EVO 35 will swing an APC 16x14 quite happily and straight line speeds are around 112mph.

quote:

ORIGINAL: Boo2

Hi,

I seem to have confused myself about converting prop rpm / pitch into plane speed in mph. Am I right in saying the prop pitch speed im mph is rpm * pitch * 60 / (12 * 3 * 1760) ?

My reason for asking is people are talking about speeds of 135 mph when the figures don't add up. Eg :

10,000 rpm * 12" pitch * 60 / (12 * 3 * 1760) = 113 mph.

Assuming 10k is the very highest the Evo35 will run and 12" is the pitch often quoted for the prop tne this is a lot less than the speeds I've seen quoted and there should really be a further fact or .8 applied for prop slip reducing the figure further to 90 mph.

Am I doing something wroing here or what ?

Thanks,

Boo


(in reply to Boo2)