SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 19, 2008, 11:19 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,608 Posts
Quote:
Originally Posted by chewytm
Hey you are right. What I said is correct in general. Maybe it's different because it's a water plane?

chewy
Actually, there's one error in your explanation--downthrust is measured relative to the wing incidence, not the horiz stab incidence. The stab incidence can either help or hurt the downthrust depending on how it's set relative to the thrust line, but that is secondary.
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 19, 2008, 11:22 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,608 Posts
Thanks, Jon! My wife took those pictures (and shot the video). She does a great job, huh?

You gotta build one of these if you like seaplanes! I'd be thrilled to see you build one. And yeah, I think tekajo is on to something!

Steve
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Old Oct 19, 2008, 11:23 PM
KK6MQJ
Bajora's Avatar
Joined Sep 2004
13,654 Posts
You have a great women there then Steve! You better hang on to her TIGHT! I have a hard time getting my wife to assist me, although if I beg and beg, she will. BUT, it usually comes with a pretty big price!

I hope to build one for sure!
Bajora is offline Find More Posts by Bajora
RCG Plus Member
Old Oct 19, 2008, 11:54 PM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
4,011 Posts
Quote:
Originally Posted by jetset44
Actually, there's one error in your explanation--downthrust is measured relative to the wing incidence, not the horiz stab incidence. The stab incidence can either help or hurt the downthrust depending on how it's set relative to the thrust line, but that is secondary.

uhh... what happens when the wing has an incidence angle? The datum would be the tailplane, otherwise, the wing would not be considered to have any incidence angle and it would be the tailplane having the incidence angle. It's a bit confusing to me but I have not really seen anyone setting an incidence angle for the tailplane, only the wings before this.

chewy
chewytm is online now Find More Posts by chewytm
Last edited by chewytm; Oct 20, 2008 at 12:00 AM.
Reply With Quote
Old Oct 20, 2008, 12:31 AM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,608 Posts
chewy,
Yes, it can get confusing depending on what you call the datum. Most often airplane designers use the fuselage centerline as the datum, which means the horiz stab often doesn't have an incidence angle but the wing often does. In the case of the Polaris I used the fuselage centerline as the datum as usual, but since the wing is set at 0 deg relative to the fuselage it's the horiz tail that has an incidence angle. Had I chosen to mount the wing on the fuselage at +2 deg incidence, then the thrustline and horiz stab would be at zero.

However, remember that the datum is only for reference and all the really matters is how EVERYTHING is set up relative to the wing. And all you have to know to understand the Polaris setup is that the thrustline and horiz stab are at -2 deg incidence relative to the wing.

Steve
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Old Oct 20, 2008, 01:33 AM
Registered User
Ipoh, Perak Malaysia
Joined Jul 2006
4,011 Posts
Steve,

Thanks for the explanation. I think it is just a case of the glass being half full or half empty, but the effects are the same. The force vectors are the same whether the glass is half full or half empty.

chewy
chewytm is online now Find More Posts by chewytm
Reply With Quote
Old Oct 20, 2008, 07:07 AM
We shall serve the Lord
kingsflyer's Avatar
United States, TX, Kingsland
Joined Sep 2005
5,061 Posts
Quote:
Originally Posted by darkseacret
has any one had any luck with C-RC 232 electronic spray . I cant seem to find any corrosion x here in town
We've has some folks try the C-RC 232 spray, but it doesn't seem to work as well as the CorrosionX. I'd recommend you try and mail order it if you can't find it locally.

Mike McD
kingsflyer is offline Find More Posts by kingsflyer
RCG Plus Member
Latest blog entry: LEDs on my T-28
Reply With Quote
Old Oct 20, 2008, 07:44 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,912 Posts
Thanks Steve - I was also thinking if the stab was at 0, it would be acted on by the of the prop rush giving it more downthrust.

I can't beleive that little Suppo 2212-6 can operate at 22A continuous but I guess it does. Amazing!
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Oct 20, 2008, 08:10 AM
Registered User
Wilmington, N.C.
Joined Jan 2008
203 Posts
no need for the spray anything anytime soon this mornings re remaiden off grass went well for about 3min. of twitchy to much throw, no expo super grin flight when what the ! No elevetor response . nose down this time a pretty good crunch of front fusalage, damn at least my esc isnt wet . A full rebuild is in order with my better radio (7uacp) and no e-sky servos
darkseacret is offline Find More Posts by darkseacret
Reply With Quote
Old Oct 20, 2008, 08:46 AM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
2,501 Posts
Darkseacret - D n! You have had the worst luck with this plane. Rebuild it. It flies so sweet, it will be worth the effort. My total flights on this plane is now 13 and flight time is 107 minutes. Thats over an hour and a half of air time. (and I have yet to fly off of water, all is from grass in field behind my house). I've almost worn the paint off the bottom from doing touch and go's from the grass. I'm glad that I fiberglassed the bottom.

Weather is beautiful, I think I will go get in another flight.

Tony

PS Barnesjonr, you really should build this one. I know your plate is full but...........
tpfing is offline Find More Posts by tpfing
RCG Plus Member
Latest blog entry: North Las Vegas 1971
Reply With Quote
Old Oct 21, 2008, 07:14 PM
Registered User
Wilmington, N.C.
Joined Jan 2008
203 Posts
Even though shes toast now I thought you might like my polaris pic quess were I got the paint inspiration
darkseacret is offline Find More Posts by darkseacret
Reply With Quote
Old Oct 24, 2008, 02:49 AM
Registered User
Winterswijk, Netherlands
Joined Jun 2007
133 Posts
It Flies !

Finished my Polaris, and it FLIES !.

Used a Turnigy TR35-30A-1700 motor on a 7x6 APC prop which I had lying around. Power nearly 300 watts.

Added some tail bracings from 3mm CF tube, as under full power, the entire tail was bending under the load, and also as the motor is approx 77 grams, I was afraid that a hard landing might break the tail off.

Mounted the ESC with the cooling element sticking through the foam, and waterproofed it on the edges with UHU Por. Was worried it might overheat if left inside without any cooling.

Don't know top speed, but it's pretty fast... Flies nicely on 1/3 trottle.

It went completely submerged this morning on takeoff... Elevator pushrod came loose . No harm done, and no water entered.... It was able to cruise back to shore without problem.

Yesterday, on the maiden flight, the ESC failed... I waterproofed it with CRC 2-26... Cannot get Corrosion-X over here. ESC was completely dry, perhaps it didn't like the waterproofing after all... ESC had many flights already on different planes. Worked OK for a few minutes after I waterproofed it, but then lost power, and then failed completely...
Had to swim to get her back.... No worries, Here in Thailand it never gets cold .

New ESC not waterproofed... it should be in a watertight compartement, and it held out ok so far (even after today's 'submarine experience')

Beautiful plane, and flies excellent

Thanks again Steve for the great design !

Wilco.
wilco1967 is online now Find More Posts by wilco1967
Last edited by wilco1967; Oct 24, 2008 at 04:03 AM.
Reply With Quote
Old Oct 24, 2008, 03:50 PM
Park Jet Guru
jetset44's Avatar
Seattle, WA
Joined Jun 2002
5,608 Posts
Great looking model, Wilco. You're welcome for the plans! Glad to see you've enjoyed them, minus the swim, of course...

Wow, 300 watts is indeed a lot of power for this model--no wonder the tail was bending under the load! You certainly solved that issue though with the external bracing.

Steve
jetset44 is offline Find More Posts by jetset44
Reply With Quote
Old Oct 26, 2008, 10:44 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,912 Posts
Flew the plane yesterday and like you said, no issues with flight characteriestics. Flew true as built. I'm still working on landings as that nose up (ala SST's) attitude at slow speeds is a little strange to me. Got to get the tail on the ground before chopping the throttle or come in fast and have it slide quite aways. Overall, I'm quite pleased with it and many thanks again for the plans.
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Oct 26, 2008, 11:11 AM
Retired and Lovin' it!
United States, KY, Sturgis
Joined Jul 2007
2,501 Posts
Hoppy, I fly exclusively from grass with mine and I come in fairly level and a little hot and let it slide. That's also great for touch and goes. Just bring the power back on while sliding and take off again.

Tony
tpfing is offline Find More Posts by tpfing
RCG Plus Member
Latest blog entry: North Las Vegas 1971
Reply With Quote
Reply


Thread Tools