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Launch Altitude - 9/21/2003 7:09:58 AM   
zxcv11



Posts: 380
Joined: 9/11/2003
From: Glenshaw, PA, USA
Status: offline 		I was wondering if anyone here was familliar with how much altitude one could achieve using a COX BlackWidow .049? I have heard as much as 300 ft. I think. Is it worth it to use vs. a home-made Hi-flight?(..up to 300ft.??) Where would you find the tubing for the high-flight? Anyone who has some input on the various launching methods(aside from winch....NOT in the budget ... )please weigh in on this.

Thanx,
Brian
       Post #: 1

RE: Launch Altitude - 9/21/2003 10:09:21 AM   
probligo



Posts: 354
Joined: 5/13/2002
From: opononi, NEW ZEALAND
Status: offline 		Well, I have seen 48" or thereabouts 2ch oldtimers getting to 800 ft plus with a Cox 049 Texaco.

I have seen 2m gliders getting 400 ft on a good day from a standard bungee.

I have seen F3J's pinging off a winch at close to 800 ft.

It depends upon so many factors, not the least of which is the skill of the pilot.

(in reply to zxcv11)
       Post #: 2

RE: Launch Altitude - 9/21/2003 2:59:23 PM   
Jack Hyde


 

Posts: 606
Joined: 6/18/2002
From: Red Bluff, CA, USA
Status: offline 		If the .049 engine will lift the plane at all the max altitude it can produce depends on how much fuel you can carry. A 2 lb sailplane with a sink rate of 2 fps requires 4 ft-lb/per sec to maintain level flight ,any more power can be used to raise the plane. A horse power is 550 ft-lb/sec. If the .049 produces .1 hp it uses .01 to maintain level flight and has .09 available to lift the plane. It can lift the plane at 25 fps for as long as the engine runs. This is all order of magnitude estimates but the idea may apply.
The main thing wrong with having an engine on the front is drag increases a lot and the sailplane doesn't sail so well.
You can find a lot of talk about where to get histart elastic by searching the forum. It comes up once a week.

(in reply to zxcv11)
       Post #: 3

RE: Launch Altitude - 9/21/2003 10:54:35 PM   
zxcv11



Posts: 380
Joined: 9/11/2003
From: Glenshaw, PA, USA
Status: offline 		Thanx for the input guys. FYI I'm going to be flying a Gentle Lady (my first flying plane<2nd build>...as far as skill goes probligo, as I'm sure you can see my beginner status ), and I've built a SIG power pod to mount the .049. I like the fact of not permanently mounting it, but I am also very concerned about drag...esp. with the pod. The gas tank pre-mounted on the BW is 8 cc. (0.28fl oz.)
I'm not too sure about the final weight of the glider yet, but it should come in right on the 22-25 ounces called for in the Goldberg plan. Of course, add another 2.26 oz. in engine...1/8 oz. for pod...1/4 oz. for fuel+drag factors...which I have no clue about yet But I'm on my way!!
Thanx again guys
Brian

(in reply to zxcv11)
       Post #: 4

RE: Launch Altitude - 9/27/2003 3:29:21 AM   
tunabiker


 

Posts: 41
Joined: 9/26/2003
From: Del Mar, CA, USA
Status: offline
I have been learning for several weeks using the winch at the club and suffering the self inflicted embarassment of low skills in front of the expert members. Then I started using my hi-start. It is as it came from the Dynaflite box, so less than 100' of surgical tubing and maybe 500' of string. On my Gentle Lady, I paced back first 35 steps, then 40 and now 50 getting more confident as my experience grew. I just let it fly off the bungee and don't "dip" and find that I get plenty of height and lots of control. Much better than worrying about folding the wings on the winch. Height is maybe 300', maybe more. The lift is gentle and that suits me fine. As the skills get better, I'll get more aggressive, but for now I suggest you take a similar route. The guys are very well intentioned, but just being a little away from them, I find my self confidence is growing much faster. Still, they're available for both questions and criticism!
Bill in So. Cal.

(in reply to zxcv11)
       Post #: 5

RE: Launch Altitude - 10/18/2003 5:08:37 AM   
aeajr



Posts: 5496
Joined: 1/14/2003
From: Long Island, NY, USA
Status: offline 		I have about 60 hi-start launches on my Spirit select and love it. I find the winch much harder to use. In fact I destroyed my Spirit select two weeks ago on the winch.

I am building a new one now and will stay with the hi-start. I am getting 400-500' launches and am very happy with it.

_____________________________

Clear Skies and Safe Flying!
Ed Anderson
Moderator
Park Pilot Program Partner

(in reply to tunabiker)
       Post #: 6

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