Discussion Scaled down Lanzo Bomber ?

[starzak]

Anyone flying a reduced version of the Bomber on electric ? Just wondering what size that you scaled it down to, what electric components you used, and how does it go ?

[adamtc]

having just built the bombers sister, a record breaker and massively overpowered it with an e flite 60, you could fly the full size 96 inch span version easily on a 40fs equivalent.

An eflite 25 on 3 cells would do a 1/2 or 1/3 scale easily.

[BMatthews]

Nothing specific for you but here's sort of what I use as guidelines for powering old timers and other lighter wing loading "soaring" models.

30 to 35 watts per lb will produce a gentle J3 Cub like or slightly stronger climb angle. You'll get to around 500 to 600 feet up at full power in about 60 to 80 seconds depending on the small things.

70 to 80 watts per lb should provide a nice spiral climb more or less typical of the hotter spark engine options of the day. Likey in the 50 to 60 degree climb angle range. Time to reach 500 to 600 feet will shorten to around 20 to 30 seconds of full power climb.

100 and up is getting into true vertical or close to it with greater power options just making the speed get higher.

These numbers pretty much apply for anything from 3 to 10 feet span for old timers and electric powered sailplanes from all I've seen and experienced.

For climb performance you want to stick with relatively low Kv value motors that will turn bigger props. Check the recomended prop sizes for different motors to get a feel for this. A lower Kv becomes more important if you want to run more than 3 cells in series as well since the more cells the smaller the prop needs to be to avoid high currents and running the motor and cells too close to max power. Yes, they may not burn out right away but you'll get longer battery life if you don't stress them much past 80% of their rated C value. Especially in a pack where the inner cells can't dissapate the heat as easily.

[Harry D]

Bombers have been built in just about every size possible and no doubt we'll be hearing all about them.

The August 2009 issue of RC Micro World online magazine has an excellent 17-page construction article (including free plan) by Bob Aberle, for a really small and light Bomber. I don't think they'll mind me posting their specs of this model here:

SPECIFICATIONS
Model: Lanzo “BOMBER” (circa 1938!) – (reduced from original size)
Type: An electric powered old timer free-flight design converted to RC
Wingspan: 38.5 inches
Wing Area: 200 square inches
Length: 23 inches
Weight: 5.5 ounces (with a 2 cell 210 or 250 battery pack)
Wing Loading 4.0 oz/sq.ft.

GEAR USED:
BP Hobbies/Corona RD-620 receiver with an E-Cubed RC micro receiver antenna., Polk’s Tracker-III transmitter, one Blue Arrow BA-TS-2.5 G micro servo and one FMA PS-20 micro servo

POWER SYSTEM USED:
Uttam’s Mighty Midget 13/4/15T Gold Series brushless outrunner motor available from Bob Selman Designs, Castle Creations Phoenix-10 ESC w/BEC, GWS 5 X 3 prop, battery (Lazertoys 2 cell 210 or 250 mAh both at 0.5 ounce, E-Flite 2 cell 430 mAh at 1.1 ounces and a ParkZone 2 cell 800 mAh pack at 1.6 ounces) (using the 210 pack the battery actual load for this application = 10.6C with a stated rating of 12C)

POWER SYSTEM (parameters)
Motor current: 2.23 amps
Voltage: 7.73 volts
Power Input: 17 watts
Power Loading: 49.6 watts/pound
Flight Time: 8 to 10 minutes with some motor throttling (on the 210 mAh pack). The 430 mAh pack can easily double that time!


BTW, RC Micro World has to be the best bargain around. At the moment, $6 will get you a subscription for the last 3 months of 2009, and also gives you access to all issues going back to mid 2005. http://www.cloud9rc.com/

[David Hipperson]

Just look up Bob Holman (bhp.com I think) and you'll find reduced plans and laser cut parts.

[Jim Kraft]

Here is my 60" Bomber with an Ohlsson 23 sideport. It is a little on the heavy side with all of the ignition stuff and radio, but the little Ohlsson takes it up in a hurry. I built it from a Klarick short kit.

[starzak]

Jim Kraft, and others. I will be building a 58", 440 sq in version, similar in size to yours, but I'm thinking somewhat lighter. It's from plans by Jim O'Reilly, and I'll be using a Hacker A 20-26 M with a RPM/V of 1130, operating current of 12 A, Peak Watts of 150. The motor weighs 1.48 ozs. Using just 2 LiPo cells, do you think that this combination will have a reasonable climb rate ?

This newbie thanks you.

zak

[coosbaylumber]

This may be a repeat of same question as mentioned at RCUniverse recently.

But this has ben done numerous times already. Go to SAMTalk and look through their data bank there.

And stay away from any of the Ben Buckle kits.


Wm.

[starzak]

SAMTalk not good for me. They refuse to listen and talk to me, because my antique computer here is running Windows 98. SNOBS !

[Gluehand]

A vintage forum should accept vintage operative systems as well....just logical thinking....

[starzak]

Estimated weight for the 58" Lanzo Bomber is 24 oz.

I'll be using a Hacker A 20-26 M with a RPM/V of 1130, operating current of 12 A, Peak Watts of 150. The motor weighs 1.48 ozs. Using just 2 LiPo cells, do you think that this combination will have a reasonable climb rate ?

Thanks.

zak

[tony lechauve]

Can I ask coosbaylumber and others, without starting a libel case, why should I stay away from Ben Buckle kits? As a Newbe it seemed a comfortable way in to a first proper build (tho so far they have failed to answer an email and reminder so maybe I have 1/2 an answer already?). Thanks

[vintage1]

Originally Posted by tony lechauve

Can I ask coosbaylumber and others, without starting a libel case, why should I stay away from Ben Buckle kits? As a Newbe it seemed a comfortable way in to a first proper build (tho so far they have failed to answer an email and reminder so maybe I have 1/2 an answer already?). Thanks

Because the kits haven't changed since whenever, the wood quality is variable, the cutting irregular, and the customer service not brilliant.

Having said that, the kits do build. Its just a lot of extra work sometimes that shouldn't be. The plans are usually pretty good.

[Leadchucker]

Originally Posted by adamtc

having just built the bombers sister, a record breaker and massively overpowered it with an e flite 60, you could fly the full size 96 inch span version easily on a 40fs equivalent.

I am using a HUR/C 3548-09 spinning a 13 x 6.5E APC on a full size LRB and it's plenty of power. Remember the original had a Brown Jr. making a whole 1/6 HP turning a 14 x 8 prop @ 7000 rpms on a good day. I have powered the LRB with a O&R .60 sideport (free flight),another with a Super Cyke (R/C),another with a Brown Jr (free flight) and the current one (R/C and build No.4) as described with electric. Avatar was Free flight LRB No.1 with O&R, she went after a station wagon she didn't like but lost the fight.

[adamtc]

tony,

BB Kits are not advisable for beginners. Trust me, the lure of a 'kit' will soon fade when you see what you have actually bought. Ive had 3 kits from BB and all had parts that were badly cut and didnt match the plans, some so bad, I thought I had parts for a different model. Experienced builders can work these problems through but not if your new to all this.

For starters, go to belair kits if in the uk. He does laser cut part kits inc vintage, so that all the fiddly bits are done for you along with a plan. Buy your strip material at your local shop or online ( I use balsa cabin- vvvvv good).

In the end, its cheaper and you get a much better model without the hassle of recutting and faffing with poor quality bandsaw cut bits.
My record breaker is from there and it was a joy to build.