RE: Sig P-51B gas+build thread (Full Version)

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G-Pete -> RE: Sig P-51B gas+build thread (2/5/2008 4:26:35 PM)


quote:

ORIGINAL: NoFlaps

...And here's the installed engine.[;)]
Unfortunately, it looks like I'll have a pretty big hole in the cheek of this plane...I wish someone would invent smaller gasoline carburators.
I'd do it, but I don't have the time.[8|]

Hi,

I would highly suggest you use some 3/4 inch hard wood dowels for your engine stand offs. These plastic ones will compress and loosen up your engine and create a high vibration point, this could lead to failure of the firewall.

happy landings
G-Pete




NoFlaps -> RE: Sig P-51B gas+build thread (2/5/2008 4:29:59 PM)

Gpete...thanks for the tip.
I originally wanted to use them, but the local hobbyshop didn't carry anything that big, so i chose the nylon biolts thinking that would dampen some vibration.
Who carries the hardwood stock ?
Home Depot ?



jmohn -> RE: Sig P-51B gas+build thread (2/5/2008 4:42:47 PM)

NoFlaps,

Cool radiator scoop! I may have to do that for my summer flying as I suspect my battery and ESC will get hot as there's not a lot of air moving through the plane right now. Don't need much since it's in the 40-50s out here right now [:)]

I am going to try a gyro on the tail wheel to help ground steering. It steers pretty well, but I want to test it for my Stuka as it's suposed to be a little squirly on the ground.

I still haven't gotten a good day to get some video. It looks like today at lunchtime might be a good day. It was way too windy yesterday for a flight. I will post the video as soon as it's ready.


Jeff



G-Pete -> RE: Sig P-51B gas+build thread (2/5/2008 5:01:58 PM)

Yes, Home Depot is a good source. I harden the ends (after cutting to length) with CA, just drop CA on it it will disappear in no time.
BTW: I use hardwood dowels also on my 100cc....[;)]

good luck

happy landings
G-Pete



Evil_Merlin -> RE: Sig P-51B gas+build thread (2/5/2008 5:15:01 PM)

Great work NoFlaps.



kochj -> RE: Sig P-51B gas+build thread (2/6/2008 6:40:07 AM)

The mustang looks great guys.....

NF,
I was wondering how to finish inside that radiator exit port!
It that how it actually looks on the inside?

I just finished mine on my Giant p51D....
not sure if it will cause pitch changes when deplyed?
little more cumbersome way of doing it though, but I wanted to practice doing it this way because I wanted to put inner doors on it someday..
I made a fiberglass mold and then made a direct fit out of fiberglass..

Justin



NoFlaps -> RE: Sig P-51B gas+build thread (2/6/2008 2:29:07 PM)

Kochj,
I made it up on the inside...I have a bopok on Mustangs, and it gives loads of detailed drawings and exploded diagrams, but nothing on the inside.
I used a sharpie and drew a series of vertical lines, like cooling fins since I had to guess.
I'll get a better pic for you soon.
Yours looks great! [;)]



DAKOTANOVASS -> RE: Sig P-51B gas+build thread (2/6/2008 8:03:03 PM)

Here's a pic of the cooling door



bingo field -> RE: Sig P-51B gas+build thread (2/6/2008 8:12:42 PM)

Dang, NoFlaps, it's almost like you engineered the dadgum thing yourself. Very nice. Thanks for the pic Dakota.



tony-howard -> RE: Sig P-51B gas+build thread (2/7/2008 5:44:51 AM)

Ed and others

quote:

ORIGINAL: rc34074

i have a question- when I look at the way the front of this plane blends to the spinner it doesn't look right to me. the full scale mustangs I have seen do not taper to the spinner like this model does. it looks to me like they used a spinner that is too small and made the cowl taper to fit the spinner....

Ed



The angle the picture of the cowl is taken at makes all the difference on a Mustang. The top profile of the cowl is one continuous smooth curve. But if the cowl is viewed from slightly below (or above) there is a bulge (which covers the heads on the Merlin). (see the picture below - note curve of the top cowl stringer and the shape of the first bulkhead behind the spinner)

Most ARF's don't have this, but Sig' cowl does it very accurately. It also has an exceptionally well shaped air intake scoop. I have seen the new Sig cowl and in my opinion it is the best overall scale rendition I've seen so far on any ARF. My congratulations to Mike Gretz and the folks at Sig





NoFlaps -> RE: Sig P-51B gas+build thread (2/7/2008 2:00:12 PM)

JHere atre the better pics of the rear radiator door/ unit.
I haven't touched the plane since the the last post.
this element will be painted & fuelproofed of course. I'm not sure if this will have an effect like a flap per-se, but I'm sure it will add drag, and change the amount of low pressure along the belly of the plane which is to be expected. It will be interesting to see for sure.[;)]



kochj -> RE: Sig P-51B gas+build thread (2/7/2008 3:47:51 PM)

QQQ?
on the radiator picture..
Is the pole thing somthing that is there for show to keep it open, or is it part of the hydrolicks?

Justin



DAKOTANOVASS -> RE: Sig P-51B gas+build thread (2/7/2008 4:08:04 PM)

I believe it is there for support. I have seen another pic which shows it better, but you think I can find it. If I do I will post it.



bingo field -> RE: Sig P-51B gas+build thread (2/7/2008 4:10:29 PM)

If you think about it, the radiator won't pivot, just the door. My guess is that the rod is the end of the door actuator.



DAKOTANOVASS -> RE: Sig P-51B gas+build thread (2/7/2008 4:42:02 PM)

It is the actuator for lifting the door.[URL=http://rides.webshots.com/photo/2761803060092702542XaGKjK][IMG]http://inlinethumb33.webshots.com/34080/2761803060092702542S500x500Q85.jpg[/IMG][/URL]



NoFlaps -> RE: Sig P-51B gas+build thread (2/7/2008 9:15:48 PM)

Thanks for those pics...I never would have known.[;)]
Well, I've begun the part i didn't want to get into: the cutting of the cowl for the gasoline engine...It's very disapointing just how large of a hole the carb requires.
perhaps when the nise art goes on, it'll no t be so visible, but I don't really see it getting too concealed.[X(]
So these pics are prelininary holes , the carb & muffler have not been mounted yet.
But there 3 views should give you the idea.



jmohn -> RE: Sig P-51B gas+build thread (2/7/2008 10:06:51 PM)

I don't have any holes in mine [:D]

Sorry, couldn't resist! Yeah it's too bad they can't make them smaller. Flew mine again today at lunchtime and had a blast. The only issue right now is getting the gear retracted all the way as the air pulls on the doors and makes them stay down a little. I solved that my doing an inverted retract of the gear after take off. It looks cool too [;)]


Jeff



NoFlaps -> RE: Sig P-51B gas+build thread (2/8/2008 12:00:26 AM)

Nyuck-nyuck!
[:)]
Say, are you going to put the sound sytem in yours ?
That would be wicked.
I can't wait to hear my gasser purr~



jmohn -> RE: Sig P-51B gas+build thread (2/8/2008 12:14:13 AM)

We tried the sound system on another plane earlier this year and couldn't hear it while in-flight. All it takes is one other gas plane in the sky and you can't hear it. It's great on the ground though! It's just too much $ for something you can barely hear. I would much rather spend the money on a real gas engine for the plane.


Jeff



Whistling Death -> RE: Sig P-51B gas+build thread (2/8/2008 2:46:13 AM)

quote:

ORIGINAL: NoFlaps

Thanks for those pics...I never would have known.[;)]
Well, I've begun the part i didn't want to get into: the cutting of the cowl for the gasoline engine...It's very disapointing just how large of a hole the carb requires.
perhaps when the nise art goes on, it'll no t be so visible, but I don't really see it getting too concealed.[X(]
So these pics are prelininary holes , the carb & muffler have not been mounted yet.
But there 3 views should give you the idea.


That actually doesn't look too bad especially from the front. Consider that if you had put in a Saito 91 or 100, it would have the same problem but you would have a big muffler coming out of the side and more engine sticking out of the bottom.

Is the muffler going to hit the side as well?



rc34074 -> RE: Sig P-51B gas+build thread (2/8/2008 3:13:25 AM)

found a front view of a mustang which clearly shows that my original comment is correct. the sig cowl is wrong - they used a spinner that is too small. Don't get me wrong - they did build a nice mustang- just made a mistake on the cowl/spinner transition. the engine bulge is not that big.

this is like the modeltech 40 size mustang- it tapers like this too. I saw one of those up close in Columbus recently. I wonder if the same people who designed the modeltech designed the sig.

I will post the mustang pic I found to show you what I mean - if it works for me this time.

the first pic I uploaded was kind of tiny so I added the scond which should be bigger.

Ed



tony-howard -> RE: Sig P-51B gas+build thread (2/8/2008 3:52:08 AM)

Ed

I think you're looking at pictures taken from the wrong angle ...

The full scale spinner is 28.3 dia and the fuselage is 387.31" loa (from the originall NAA drawings, spec sheets). Since Sig lists their loa as 55.9" I get a scale ratio of 6.93 for the fuselage. Using those data the correct scale spinner would be 4.09". That's pretty darned close. Admittedly the spinner may or may not have the right profile and that may create a break in the side view curve that should be one smooth flowing line from the tip of the spinner to the windscreen. Mike Gretz addressed this a few posts back, pointing out that the spinner has to be one that's commercially available.

As for the bulge, see the attached picture.

No big deal ... I just think Sig's cowl is pretty darned good.

Just my 2 cents worth.




easydave -> RE: Sig P-51B gas+build thread (2/8/2008 4:26:24 PM)

Noflaps - I just saw this plane in MA while doing Jury Duty. I built the original 1970s Vintage Top Flite Kit with flaps and Air retracts 25+ years ago. But it turned out to wiegh 12 to 13 pounds which was way to heavy. Also, I had the same thought about using Rom Air retracts and when I saw that you used them I am pretty convinced I am going to purchase the kit.

Two questions:

One - I have a like brand new YS91AC 4cycle that will turn a 15-8 prop that I was wondering if you beleive it would be enough power for the plane. Sig and Tower notes that the plane is supposed to be only 8 to 8.5 pounds. and a 90 to 100 4 Cycle is enough power. If it is really this lite then should this engine be enough power? Your thoughst?

Two - can you send a link as to where you got your instrument panel and Pilot. I was thinking of trying to install the Top Flight cockpit kit. Is it to large to use?

Finaly - thanks for posting so much info on this kit. They are charging a premium price but it is hard to not get it after reading your notes and your comments on using air retracts compared to the mechanical.

Will appreciate any comments.

Easydave



jmohn -> RE: Sig P-51B gas+build thread (2/8/2008 4:57:29 PM)

Easydave,

The mechanical retracts work great. I haven't had any issues other than they get pulled out a little at high speeds by the doors. The cowling looks great IMO and besides those photos show a P51D which has a different cowl anyway.

Here's some video of the plane in action:

http://www.youtube.com/watch?v=BTaj5rgSKFk



bingo field -> RE: Sig P-51B gas+build thread (2/8/2008 6:45:03 PM)

It looks as though you could have an Unrestricted Climb to altitude on take off. I have only seen a few 3D guys have that much umpfff.
I still want to put a 4stroke in it.. Nice video.[8D]



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