Will you ever do a scale 4 bladed prop?
Jugs!!!
- Thread starter willsonman
- Start date
Good question, Akimbo!
I'm having a hard time coming up with a 4 blade prop for my smaller Jug. 15-16", 4 blade should do it for the motor I'm going to be installing. Those seem to be hard to come by, or I just don't know where to look.
I'm having a hard time coming up with a 4 blade prop for my smaller Jug. 15-16", 4 blade should do it for the motor I'm going to be installing. Those seem to be hard to come by, or I just don't know where to look.
Generally I've come up with 4-blade big or 4-blade small. The cheapest one that I could find was $71$
http://www.troybuiltmodels.com/items/BP168-4C.html
At that price I decided against it and went with a different motor. With all that mass I would have had to to to a 12S setup which would require an Opto ESC. It gets a whole lot more dangerous when you get above 6S. It scared my nerves and my bank account. They do make smaller ones... Maybe you could consider these Pat...
http://www.hobbyexpress.com/scale_4_blade_11_x_10_variable_pitch_prop_18581_prd1.htm
or
http://www.hobbyexpress.com/scale_4_blade_9_1_2_x_10_variable_pitch_prop_18582_prd1.htm
Same style prop on my Gee Bee.
http://www.troybuiltmodels.com/items/BP168-4C.html
At that price I decided against it and went with a different motor. With all that mass I would have had to to to a 12S setup which would require an Opto ESC. It gets a whole lot more dangerous when you get above 6S. It scared my nerves and my bank account. They do make smaller ones... Maybe you could consider these Pat...
http://www.hobbyexpress.com/scale_4_blade_11_x_10_variable_pitch_prop_18581_prd1.htm
or
http://www.hobbyexpress.com/scale_4_blade_9_1_2_x_10_variable_pitch_prop_18582_prd1.htm
Same style prop on my Gee Bee.
I was hoping to find those in the size I need, but 11" is too small.
Congrats on the taxi test! Yours is looking great (of course)!
Any thoughts on removing a small bit of residue from the monokote type covering? I'm thinking acetone, but need to be careful to keep it on the dry side so it doesn't delaminate the balsa from the foam or eat the foam wing cores.
Congrats on the taxi test! Yours is looking great (of course)!
Any thoughts on removing a small bit of residue from the monokote type covering? I'm thinking acetone, but need to be careful to keep it on the dry side so it doesn't delaminate the balsa from the foam or eat the foam wing cores.
That is a good question Pat. I think that if you use acetone applied to a paper towel you can carefully remove the residue without saturating the balsa. To be sure that the glue is safe for acetone try using a q-tip or other swab, dip it in the acetone and apply it lightly to a non-critical glue joint that is easily accessible. If you observe the glue dissolving let it dry out and re-apply glue and then you know. I think you may also find that sanding may remove some of the residue as well.
The blades on those variable pitch props are quite flimsy. So going higher than 6-700W would not be a good idea. I think that you may have to make a compromise here, as I did. 2-blade prop only. Its more efficient and there is less mass to spin up. Less mass means less torque on the airframe if you have to throttle up on a bad landing approach with a faster spin-up rate to recover. Four our smaller applications 2-blade is a far more efficient option both in terms of thrust and speed. If you are going with the NTM motor I suggested an APC-E 15x10 prop will suit you very well on a 4S battery. Again, its the exact same combo I have in my 69" Texan that really hauls the mail and comes down cool.
The blades on those variable pitch props are quite flimsy. So going higher than 6-700W would not be a good idea. I think that you may have to make a compromise here, as I did. 2-blade prop only. Its more efficient and there is less mass to spin up. Less mass means less torque on the airframe if you have to throttle up on a bad landing approach with a faster spin-up rate to recover. Four our smaller applications 2-blade is a far more efficient option both in terms of thrust and speed. If you are going with the NTM motor I suggested an APC-E 15x10 prop will suit you very well on a 4S battery. Again, its the exact same combo I have in my 69" Texan that really hauls the mail and comes down cool.
$71 for a prop? Holy crap!
My dad built a smaller plane years ago for display and had a thought that would work well, at least for times when it ISN'T flying... He took two regular props and cut a relief into each, so they could be simply fit together forming a 4 blade prop. While not quite the best idea for actual flying, it certainly gives it the proper look when on the ground.
So, I realized that I never posted an issue I'm having on this project.
I went to do power tests and with the current setup my watt meter says I'm only getting around 650W static with WOT. ALl the numbers say I should be getting close to 1200-1300W. Really not sure what to do here.
I went to do power tests and with the current setup my watt meter says I'm only getting around 650W static with WOT. ALl the numbers say I should be getting close to 1200-1300W. Really not sure what to do here.
Not sure Andre. Its the HK-010 which says 0-100A ,7.2-60V, 2-6S. So, I put the Texan on the watt meter and it says I'm only getting around 450W. Sooooo not true. I really think this meter is only good for 1000W. Time to start scouring the interwebz for clues. At any rate...
I spent some time hooking everything up today. The servo for the tail gear and the main gear were reversed so I added a servo reverser. Plugged in the ailerons and flaps and the flaps are geometric mirrors to I need another reverser there as well. I'll take a look at the servo layout for the main gear and see what I can to to eliminate that reverser.
I setup a clean slate on my Tx for the Jug and got things moving right and did another taxi test. The landing gear is the next step mechanically. When Taxiing the wheels are toed outward. This is a major no-no for take-offs. Better to toe in than out, otherwise things will be all squirrely.
Did another run up and I really do think that the power is fine. There is clearly a limit at about 3/4 throttle where the prop begins to stall. I expect this for the pitch of this prop.
I spent some time hooking everything up today. The servo for the tail gear and the main gear were reversed so I added a servo reverser. Plugged in the ailerons and flaps and the flaps are geometric mirrors to I need another reverser there as well. I'll take a look at the servo layout for the main gear and see what I can to to eliminate that reverser.
I setup a clean slate on my Tx for the Jug and got things moving right and did another taxi test. The landing gear is the next step mechanically. When Taxiing the wheels are toed outward. This is a major no-no for take-offs. Better to toe in than out, otherwise things will be all squirrely.
Did another run up and I really do think that the power is fine. There is clearly a limit at about 3/4 throttle where the prop begins to stall. I expect this for the pitch of this prop.
So I got the oleo struts on and got the flaps fixed. The original owner had them setup as centered and so it was not using the full travel of the servo. Almost like he had not setup flaps before but I'm not accusing. Simple fix that took all of 15 minutes to do. Got my end points right. Looks like I have about 60 degrees of deflection on the flaps. I seriously doubt that I will use that but hey... I've got it! All that is greally left is to put on the magnets to secure the battery hatch and go maiden. Of course my charger is limited with these batteries so I can only charge at 3.3A. Its an older charger but does the job fine for my other batteries, which are much smaller.
Made it to the field tonight. Weather was HOT but no wind and cloud cover on the sunset for no glare. I Got it all assembled and wheeled it to the runway. By the time I got there one of the oleos had turned. Not tight enough. So packed up and headed home.
Got back to the field today. Taxi tests are good but range test failed.
While I wait for another opportunity to maiden I wrapped up the magnetic battery hatch. STUPID strong hold but I really dont want the wind to pull it up in-flight. These are magnets from an old hard drive. I use my dremel to cut little squares. Free strong magnets... cant beat the price.
Attachments
When the weather clears. Sporadic showers forecast for the next few days. I'm back on the road next week for work so maybe at the end of the month.
Made another trip to the field last night. Conditions were absolutely PERFECT. No joy. I thought I had fixed my range issue but no. I had installed a new antenna (72MHz) to the receiver and had issues again. I tried trimming a little at a time with no change. I've never heard of issues with fiberglass fuselages, only when carbon fiber was involved but there is none on this airplane. I'm only in need of 6 channels so I think I will sacrifice a 2.4 Rx from another plane and see where we are. I have a club meeting on Wednesday (tomorrow) evening and weather may be promising. We shall see.
Ok, made a switch to a LemonRx receiver. My lovely assistant (my wife) was taking out the recycling so I snagged her to babysit while I hiked down the street. Its a DSM2 Rx and in a noisy (signal that is) neighborhood there was not so much as a single twitch. So, with that, I am set for my club meeting tomorrow. Weather permitting of course.
ExperimentalRC
Senior Member
I remember hearing something about dsm2 lockouts during flying events with many 2.4ghz receivers. I can't remember where I heard it or if its credible, but I would upgrade to dsmx before I maiden. It would be a shame to get a lockout on the maiden.
