Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Scratch and Kit Built Aircraft
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Scratch and Kit Built Aircraft Discuss and share your scratch built or kit built aircraft as well as building techniques, methods, mediums and resources.

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 10-30-2013, 07:40 PM   #1
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default Mountain Models P51

Hi Folks. Thanks for reading this
I am working on the Mountain models P-51. I am looking for people who have already built this. I have a few questions

1st and biggest
What is up with the Vertical Stab and covering. It is really strange the way this goes to gether... There is an air foil through the middle and top of it but at the bottom there is not. How is this to be covered well. I have seen people do Fillets and yet still haven't seen it done to where it looks really right. I am actually thinking about just getting rid of the foil all together This of course would mean doing it on the rudder as well. Any comments?

I will shoot a pic later I am at work right now

2nd.
Brian always seems to recommend inrunners and gearbox's. I have decided to use a 950 kv brushless weighing in at about 70 grams and 230 watts. and a 3 blade 10X7 from Master Airscrew. I calculated about 8500 RPM on a 3 cell this should give me in the 2.8 lb thrust range and a static speed of around 60

Is this to heavy?
is this to fast?
should I make flaps to compensate for the added weight? (I hate flaps)
I don't want this thing to float around like a cub, but I do want it to survive the initial flite

If you have put one of these together. Please give me some input!
drummaker is offline  
  Reply With Quote
Old 10-30-2013, 11:19 PM   #2
buzzltyr
Member
 
buzzltyr's Avatar
 
Join Date: Sep 2005
Posts: 297
Thanked 41 Times in 40 Posts
iTrader: (0)
Friends: (4)
Default

Drummaker, I built one a long time ago. One of the first kits Brian sold, actually. Your motor sounds like a bit of overkill. Brian does sell an outrunner mount that will slide onto the gearbox mounting stick, which maintains the thrust line.

I don't remember the vertical fin being airfoiled. Doing fillets with covering is challenging, to be sure. I'd practice with a mock vertical fin and see if you can get the covering to do what you want.

I'd also suggest that if you have any questions about the motor or the kit, you contact Brian directly. He is very knowledgeable and while he has a busy life, he will do whatever he can to help you.

Mark
buzzltyr is offline  
  Reply With Quote
Old 10-31-2013, 03:39 AM   #3
Stevephoon
Member
 
Stevephoon's Avatar
 
Join Date: Aug 2005
Location: White Lake, MI
Posts: 877
View Stevephoon's Gallery40
Thanked 92 Times in 91 Posts
Club: United Flying Organization
iTrader: (0)
Friends: (7)
Default

Hi Drummaker,

I have a MM P-51 as well and did a build thread here as well.
http://www.wattflyer.com/forums/showthread.php?t=55367

I some sheeting for the bottom of the fin. It worked out well. See my thread and let me know if you have any questions.

Also... I used a variety of stick mounts and settled on a 180 Watt (or so) motor and 1300 mAh batteries. It flies real well with this setup.

Steve

Growing the fleet!
Stevephoon is offline  
  Reply With Quote
Old 10-31-2013, 03:27 PM   #4
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by Stevephoon View Post
Hi Drummaker,

I have a MM P-51 as well and did a build thread here as well.
http://www.wattflyer.com/forums/showthread.php?t=55367

I some sheeting for the bottom of the fin. It worked out well. See my thread and let me know if you have any questions.

Also... I used a variety of stick mounts and settled on a 180 Watt (or so) motor and 1300 mAh batteries. It flies real well with this setup.

Steve

Hey Steve, Thanks for the reply did you wind up using the EMax 2215/25
if so that looks to be similar to what I am putting at least weight wise and power wise. Mine can generate a little more power

So because of the added weight do you come in pretty hot?
How fast is it.
was it easy to get CG right?
Oh what did you do about the hinges on the rudder, I am worried that with a taper I will still have to have a big gap to make it work because of the width. I am actually thinking about building the front edge up so I can taper over a longer distance.

I have decided to do a fillet on the bottom of the VS tapering from fuselage shape front to nothing at the back. Is there a reason you didn't do this?

Also I have seen that no one seems to cover the part of the canopy that is supposed to be colored with covering. I believe I can get it go be pretty smooth If I do that... So why does everyone paint?
drummaker is offline  
  Reply With Quote
Old 11-01-2013, 12:51 AM   #5
Stevephoon
Member
 
Stevephoon's Avatar
 
Join Date: Aug 2005
Location: White Lake, MI
Posts: 877
View Stevephoon's Gallery40
Thanked 92 Times in 91 Posts
Club: United Flying Organization
iTrader: (0)
Friends: (7)
Default

Originally Posted by drummaker View Post
....did you wind up using the EMax 2215/25
....
Nope, I switched to 180 watt, 1000 kv bell motor. ( TowerPro 2409-18T 2.3 ounce, 1000KV, 180 watt motor ) One that does not seem to be available any more. I wanted a slightly higher kv motor for a slightly higher speed...

Originally Posted by drummaker View Post
So because of the added weight do you come in pretty hot?
How fast is it.
was it easy to get CG right?
....
CG was no problem, it's not a speed demon, but nice speed for a park flier, and it slows down really well. Not hot at landing at all. Do be careful to not slow down too much, like most warbirds I get a nasty tip over if I stall. Explore the stall characteristics up at a recoverable altitude to see what happens to yours.


Originally Posted by drummaker View Post
.... hinges ....
Just CA hinges per instructions. No problems for me...

Originally Posted by drummaker View Post
I have decided to do a fillet on the bottom of the VS tapering from fuselage shape front to nothing at the back. Is there a reason you didn't do this?
I just built per instructions. Why ?? I figured Brian from MM knew best!

Originally Posted by drummaker View Post
Also I have seen that no one seems to cover the part of the canopy that is supposed to be colored with covering. I believe I can get it go be pretty smooth If I do that... So why does everyone paint?
I have warped plastic from the heat trying to apply covering over plastic. Try some scraps first and experiment. It may work at low temps.

Steve

Growing the fleet!
Stevephoon is offline  
  Reply With Quote
Old 11-08-2013, 12:59 PM   #6
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default Hmmm

OK I admit that I power all my planes way too much...

Anyway war birds don't excite me that much so I am now at a funny spot. As I started thinking about sheeting the tail section and realized just how light 1/32 balsa really is, I have decided that I think I will..............

Use a motor I have laying around... I have a 35 mm 600 watt 1,250 kv motor laying around just wishing I would put it in something fast. So I think I am going to sheet the whole plane. Make a taper on the wing where the radiator would go, and Way over power this plane. there is only about 5 extra ounces involved in adding this motor and I figure a maybe 3 or so in sheeting. I want to build an airplane that is FAST

I was inspired by the introduction of the Roc Hobby's Strega http://www.motionrc.com/rochobby-str...-wingspan-pnp/

I believe I can build plenty sturdy with sheeting. I figure I will need to reinforce the landing supports and do away with the retracts. The servo will save me some extra weight, and finding retracts for this size plane which are more than marginally strong enough is not easy. I also figure I will have to add flaps. YES?

anyway anyone want to comment on the feasibility of this?
drummaker is offline  
  Reply With Quote
Old 11-08-2013, 05:07 PM   #7
Stevephoon
Member
 
Stevephoon's Avatar
 
Join Date: Aug 2005
Location: White Lake, MI
Posts: 877
View Stevephoon's Gallery40
Thanked 92 Times in 91 Posts
Club: United Flying Organization
iTrader: (0)
Friends: (7)
Default

Wow, 600 Watts! I am not sure about that, but I like to go the other way with my builds. (LIGHT!)

That said, there is a large build thread over on RCGroups where they were completely sheeting and overpowering this kit. Take a look at this thread and maybe you can pick a few things up.

http://www.rcgroups.com/forums/showthread.php?t=614984

In general, you are correct about the retracts. They most likely will not last long if your planes weighs too much.

Anything is possible! Good Luck.

Steve

Growing the fleet!
Stevephoon is offline  
  Reply With Quote
Old 11-11-2013, 06:03 PM   #8
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

I am well under way and have sheeted the main wing and most of the fuselage. I am staring at the fuselage and thinking about the scoop where the radiator would go.

I am seriously thinking about modifying the fuselage so that the scoop is no longer needed under the wing and so that back ofthe wing is just about flush with the fuselage. This would seriously reduce drag.


I know this is a personal thing. But what do you think? Is this Sacrilege?
drummaker is offline  
  Reply With Quote
Old 11-11-2013, 07:45 PM   #9
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,418
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by drummaker View Post
I believe I can build plenty sturdy with sheeting. I figure I will need to reinforce the landing supports and do away with the retracts. The servo will save me some extra weight, and finding retracts for this size plane which are more than marginally strong enough is not easy. I also figure I will have to add flaps. YES?

anyway anyone want to comment on the feasibility of this?
I had a P51 model several years ago that was electrified with a Hacker A50-12S motor, and a 6S2P A123 battery pack. Due to our grass field, retracts were not installed.

That was a very nice flying model that could do just about anything you desired. The model was equipped with flaps. This model was very fast, and flaps really helped during landings.

The only problem with this model, the wings were a to attach. The wing hold down screws were buried inside the fuse, and you could only turn them 1/8 revolution at a time. A real pain.

The model got sold, and was replaced with the Kantana model, also a very nice model no longer available.


Attached Thumbnails
Click image for larger version

Name:	P-51 - WF.jpg
Views:	32
Size:	231.6 KB
ID:	171881
Click image for larger version

Name:	P-51 II WF.jpg
Views:	59
Size:	149.3 KB
ID:	171882

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 11-12-2013, 04:24 PM   #10
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by kyleservicetech View Post
I had a P51 model several years ago that was electrified with a Hacker A50-12S motor, and a 6S2P A123 battery pack. Due to our grass field, retracts were not installed.

That was a very nice flying model that could do just about anything you desired. The model was equipped with flaps. This model was very fast, and flaps really helped during landings.

The only problem with this model, the wings were a to attach. The wing hold down screws were buried inside the fuse, and you could only turn them 1/8 revolution at a time. A real pain.

The model got sold, and was replaced with the Kantana model, also a very nice model no longer available.
Wow that was a whole lota motor

What was the wingspan of that plane?
drummaker is offline  
  Reply With Quote
Old 11-12-2013, 05:10 PM   #11
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,418
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by drummaker View Post
Wow that was a whole lota motor

What was the wingspan of that plane?
H'mmm
Something like 65 inches or so.

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 11-12-2013, 07:57 PM   #12
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by kyleservicetech View Post
H'mmm
Something like 65 inches or so.
so it doesn't seem like I am Quite so out of line here with 600 watts on a 39"
at least I don't think
drummaker is offline  
  Reply With Quote
Old 11-12-2013, 09:13 PM   #13
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,418
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by drummaker View Post
so it doesn't seem like I am Quite so out of line here with 600 watts on a 39"
at least I don't think
That 600 watts on a 39 inch model?

A very high powered electric model would run perhaps 200 watts per pound of airplane. And, one that should fly straight up out of sight needs perhaps 150 watts per pound.

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 11-13-2013, 02:46 AM   #14
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by kyleservicetech View Post
That 600 watts on a 39 inch model?

A very high powered electric model would run perhaps 200 watts per pound of airplane. And, one that should fly straight up out of sight needs perhaps 150 watts per pound.
Yup. I am concerned too, but i can't seem to get any of the calculators t say 85+ mph with mush less...

I have. Been looking at a 400 watt bell type which is 1400 kv which would get there with an 8 x 6



Maybe i should do that

This will weigh about 26 oz with motor and battery
drummaker is offline  
  Reply With Quote
Old 11-21-2013, 07:45 PM   #15
rcers
Community Moderator
 
rcers's Avatar
 
Join Date: Jul 2005
Location: Trophy Club TX
Posts: 6,062
View rcers's Gallery57
Thanked 496 Times in 486 Posts
Awards Showcase

WAA-08 Pilot 
iTrader: (4)
Friends: (9)
Default

Originally Posted by drummaker View Post
Yup. I am concerned too, but i can't seem to get any of the calculators t say 85+ mph with mush less...

I have. Been looking at a 400 watt bell type which is 1400 kv which would get there with an 8 x 6....
To get speed you need pitch. Try solving the speed issue with square or over-square propellers. So 7x7 7x8 or 7x9 for all out speed. The other thing you can do is 4s for more RPM.

Think more like a pylon racer.

Mike
rcers is offline  
  Reply With Quote
Old 11-21-2013, 08:42 PM   #16
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by rcers View Post
To get speed you need pitch. Try solving the speed issue with square or over-square propellers. So 7x7 7x8 or 7x9 for all out speed. The other thing you can do is 4s for more RPM.

Think more like a pylon racer.

Mike
yes thanks for the advice. I decided to go with the 425 watt motor and still haven't picked out a prop. I was thinking 9x6 because I could get about 60 mph with crazy thrust with this motor on 3s and about 75 with 4s

wil the smaller prop IE 7" be drastically effected by the large coweling?
drummaker is offline  
  Reply With Quote
Old 11-21-2013, 08:54 PM   #17
rcers
Community Moderator
 
rcers's Avatar
 
Join Date: Jul 2005
Location: Trophy Club TX
Posts: 6,062
View rcers's Gallery57
Thanked 496 Times in 486 Posts
Awards Showcase

WAA-08 Pilot 
iTrader: (4)
Friends: (9)
Default

Originally Posted by drummaker View Post
yes thanks for the advice. I decided to go with the 425 watt motor and still haven't picked out a prop. I was thinking 9x6 because I could get about 60 mph with crazy thrust with this motor on 3s and about 75 with 4s

wil the smaller prop IE 7" be drastically effected by the large coweling?
Again - the power of the motor is important - but if you want speed you have to trade thrust (propeller length) for that.

So you go down in size and up in pitch and your airplane flies faster. The P-51 has a very slender cowl - so no issues at all with that.

So if you want speed think pitch and much higher than 6" pitch.

Mike
rcers is offline  
  Reply With Quote
Old 11-22-2013, 12:44 AM   #18
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,418
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by rcers View Post
Again - the power of the motor is important - but if you want speed you have to trade thrust (propeller length) for that.

So you go down in size and up in pitch and your airplane flies faster. The P-51 has a very slender cowl - so no issues at all with that.

So if you want speed think pitch and much higher than 6" pitch.

Mike
Yup
My P51 that I had awhile back had a Hacker A50-12S motor, 6S2P A123's (Similar to a 4400 Mah 5S LiPo), and a 15X10 APC-E prop. That model flew nice. Finally sold it, to hard to put together for flying.

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 12-15-2013, 05:58 PM   #19
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

I guess I will elaborate. As from above I sheeted this whole plane. I also reduced the size of the downward jut in back of the wing where the real model has coolers. It is only about 1/2 inch lower than the wing now. The original was about 1 inch or more. I wound up putting in a 430 watt 1,400 kv motor.

I have a large prop selection. Currently there is a 7x6. with a 3 cell it doesn't have enough thrust to go verticle and the calculator predicts a speed of around 75. This probably won't happen

with a 4 cell about 90

The all up weight came out to be 28 oz

This is not bad as the plan calls for 19-24. I wound up using 2 servo's for the retracts, 2 servos for the flaps 2 servos for the ailerons, one for the rudder and one for the elevator for a total of 7
I used an external BEC rated at 5 amps just to make sure and a 45 amp esc
so no surprise I am a little heavy. Still this should be Very doable


I have a couple of other prop choices.
Choice 2
APC 8x8
apc 7x8
The 7x8 is maybe a better choice

Both of these get me over 100 so... Keep your fingers crossed for me. I will be maidening this after:

I get a spinner which is ordered. I will build the battery try then

We get some weather with no snow on the ground and not too much wind.


Attached Thumbnails
Click image for larger version

Name:	p1.jpg
Views:	28
Size:	60.2 KB
ID:	172440
Click image for larger version

Name:	p2.jpg
Views:	34
Size:	52.4 KB
ID:	172441
Click image for larger version

Name:	p3.jpg
Views:	33
Size:	76.3 KB
ID:	172442
Click image for larger version

Name:	p4.jpg
Views:	34
Size:	92.8 KB
ID:	172443
Click image for larger version

Name:	p5.jpg
Views:	39
Size:	52.4 KB
ID:	172444
drummaker is offline  
  Reply With Quote
Old 12-16-2013, 02:56 PM   #20
BroncoSquid
Workin on it...
 
BroncoSquid's Avatar
 
Join Date: Jan 2012
Location: San Diego
Posts: 291
Thanked 8 Times in 8 Posts
Club: Bill G fan club!
iTrader: (0)
Friends: (4)
Default

Looks awesome, all you need is a white circle with a number on it and you are ready for Reno.

Waiting to read the flight report!

I'm either going to get good at flying em, or get good at fixin em!
BroncoSquid is offline  
  Reply With Quote
Old 12-16-2013, 03:04 PM   #21
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by BroncoSquid View Post
Looks awesome, all you need is a white circle with a number on it and you are ready for Reno.

Waiting to read the flight report!
Hmmm I was unaware of the white circle thing. I will check into it
drummaker is offline  
  Reply With Quote
Old 12-16-2013, 03:05 PM   #22
drummaker
Member
 
Join Date: Jan 2013
Location: Indiana
Posts: 206
Thanked 2 Times in 2 Posts
Club: South Bend RC Club
iTrader: (0)
Friends: (1)
Default

Originally Posted by drummaker View Post
Hmmm I was unaware of the white circle thing. I will check into it
PS
I am waiting for a spinner. There will be one
drummaker is offline  
  Reply With Quote
Old 12-16-2013, 04:13 PM   #23
BroncoSquid
Workin on it...
 
BroncoSquid's Avatar
 
Join Date: Jan 2012
Location: San Diego
Posts: 291
Thanked 8 Times in 8 Posts
Club: Bill G fan club!
iTrader: (0)
Friends: (4)
Default

Originally Posted by drummaker View Post
Hmmm I was unaware of the white circle thing. I will check into it
The only reason I suggested a white circle is that with your eclectic scheme, a number without some type of background might get "lost".

I'm either going to get good at flying em, or get good at fixin em!
BroncoSquid is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Scratch and Kit Built Aircraft

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Mountain Models P51 air scoop help needed sgschwartz Scratch and Kit Built Aircraft 2 01-14-2012 03:49 AM
Mountain Models Firestorm Build dumo01 Scratch and Kit Built Aircraft 36 04-03-2011 10:52 PM


All times are GMT +1. The time now is 09:58 AM.


Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.95398 seconds with 74 queries