mikes68charger

My Feedback: (34)

OK, So I have made some post about makeing my 30cc size (73in) GeeBee fast (trying to get around 100mph)

So I went with a DLE 55 with a 18X14 prop at 7400rpms This gives me a prop speed around 100mph and bird speed around 80ish.

I found a zinger 18X16 but I think this would bog the DLE 55 down. And I don't really want to go down to a 17 in prop as it It would lose thrust and may over rev the DLE 55

So I was looking at what gas motors that are avaible a little stronger than a DLE 55.

There seems to be so many out there, soIm asking you guys tohelp me narrow down my search, I have already wasted wasted money on a 52TGY, LOL

The GeeBee is comeing in at 16 1/2 pounds, and I have some lead secured on the motor, and both my reciver pack and spark pack on the fire wall to get the CG correct, so the motor can have somemore weight than the DLE 55, then I will move those packs farther back.

Im really thinking a zenoth 62cc will have the power Im wating, Im not to fond of the weight.

So I was told to look at a MT62cc wich i was told is a china clone with election ignition wich makes the motor lighter. Is this true???

So what eles is out there guys?

Thanks Mike

PS Sorry about spelling.

Iron Mike

Kweasel

My Feedback: (29)

The simple answer is a tuned pipe, you will be able to spin that 18-14 8000 rpm and quieten the exhaust at the same time. The prop will get loud though.

w8ye

My Feedback: (16)

DA-60

RTK

My Feedback: (1)

Yep, tuned pipe or more ponies.

aussiesteve

Hmm - "Wasted" money on the "cheap" option (TGY52) ? - I would call it a very valuable lesson

Performance and price go hand in hand (mostly).

BME 58 if you want off the shelf "common brand" performance at a reasonably low weight.

If you want total honesty from one who is very familiar with "larger scale racers", Call Ralph Cunningham (PM him here - his handle is "Antique"). He is not only the master of pretty much all things Zenoah (and can no doubt point you in the right direction with many proven facts regarding them - including the weight issue) but he is also "VERY" experienced with getting giant scale planes to go fast.
Just be awre that the advice he offers may not be what you are hoping for - he will be totally honest and talking from a LOT of experience though. (He ain't called "Antique" for nothing).

MTK

BME58 on ESC 55G pipe. (you will be pushing close to 7 HP at full revs). Except the engine is a little lighter than the DLE (about 1 1/2 ozs ). The DLE55 on the same pipe will get a significant boost. BME produces more HP than the DLE.

The DA60 is the heaviest but puts out somewhere in the middle between BME and DLE do. The same pipe should give you a similar boost. I believe the DLE and DA headers are interchangeable; BME requires a different flange. If you decide on a BME, piped, I have an extra header I can sell you with teflon coupler

BTW- all engines will run better on Avgas 100LL but only one of them, the BME, requires Avgas because it is compressed at the factory to use it. Sure Avgas Costs more than pump gas but, for me, the benefits outweigh the 20% cost increase. Buy Avgas at any muni airport. Pumps are often self serve with your credit card

RTK

My Feedback: (1)

I run the BME 58 on an ES composite pipe and it's a strong runner. If you run good quality premium gas you will be fine. I have also run the G62 "lite" on various pipes and it responds very well to being piped and would be an excellent choice also.

Truckracer

My Feedback: (19)

Mike,

Are you actually flying the DLE55 at this time or are you just guessing at the performance level? I can't tell for sure from your post.

Tired Old Man

My Feedback: (1)

If you really wanted a larger engine that made A LOT more power and designed to run on a pipe you would look at an MVVS 58. Unfortunately it weighs more and you're already past the point where power is not going to overcome the weight where flight quality is concerned. You blew wing loading awhile back.

mikes68charger

My Feedback: (34)

Thanks guys,

I have about 20 flight on this set up as of now. And I love the power,

Its not a 3D bird, but an old school racer, so i want it to gas as fast as I can.

I just ordered a Zinger 18X8-14 prop, from what I have read this show give me a few more RPM over the 18X14 now.

So it looks like a tune pipe will be the next thing on my list.

IF the Tune pipe will get me to 8k that will will put me at 109mph prop air speed, so I figured bird speed would be around 90ish.

I was thinking of getting a 18X16pro, I figured this would drop the RPM to 7k, that would still take the bird to the same speed as above, with stock set up.

I have been reading good things about the MT62 cc so I may give it a shot.

Thanks Mike

mikes68charger

My Feedback: (34)

Wow I was looking up the $$$ for a tune pipe for a DLE 55, and I cant belive $$$

I would much rather put the $250 for a tune pipe towards a bigger motor, as a tune pipe may only give me 500 more rpm

Truckracer

My Feedback: (19)

I would lean towards a real Zenoah G-62 converted to EI (for weight reasons) and use the ASP racing prop they use to use for AT-6 racing. Those planes flew well over 100 MPH on stock G-62s and were big heavy planes. I like the real G-62 because it is a well known engine that will stay together at high RPM and it will love it. They are also available on the used market at bargain prices.

Contact Ralph Cunningham (Antique here on RCU) for all the info you could ever ask for!

Good luck with your project!

Kweasel

My Feedback: (29)

It will be difficult to go faster while turning less rpm without adding a lot of power. Mufflers kill the power/weight of any twostroke. An open exhaust is good but loud. A tuned pipe should make better power/weight than open exhaust. One good thing about a pipe is that the extra weight is not on the firewall. Using a larger engine with a muffler will add weight and vibration with minimal power increase.

Truckracer

My Feedback: (19)

A tuned pipe is certainly a good way to go but in my experience, from watching many users .... for every one person that is successful using one, there are probably a dozen that fail because they don't understand how they work. Our original poster should be able to achieve his 100 MPH + goal quite easily using a simple muffled engine. The G-62 is quite smooth at high RPM .... I'd bet more smooth than most cantilever crank engines such as the DLE-55, etc.

And why turn fewer RPMs? A G-62 would be very happy turning 10000 and that opens the whole prop selection choice quite a bit.

mikes68charger

My Feedback: (34)

Thanks guy for the insite,

Like I have read before, a big bird doing 80 looks a lot slower than a .40sizemustang doing 80.

Its not worth distroying this amazing GeeBee for 10 more mph.

Its summer I will just enjoy.

airraptor

My Feedback: (66)

i bet your going faster than 80 with that plane.dont go off a pitch speed calc.
Also dont run AVGAS in your R/C engine your engine will not make as much power, and will build up more carbon in the chamber.

Also listen to what TOM says and the guy about the BME or MVVS/EVO. those i think would respond better to a pipe in the rpm range your looking for, the other engines are a 3D engine.

also to go fast you need 3 things:
1. light weight
2. low drag
3. High power.

You should never add weight to a race or 3D plane. move the serovs and batteries around to get the CG correct.

Look at mounting the servos as close to the front of fuselage as possible. Run pull pull on rudder and elevators. Find a tail wheel set up that saves weight over what you have or do as i do and dont even run one. Most planes will taxi on prop blast and the rudder.

that Gbee has a big open cowl. close off most of the cowl except a 3-4" slot from cowl to engine crank to direct cool air over engine but will block all air stagnating in side the cowl. make sure have baffles oaround the engine to direct airflow. have a 2-1 ratio onexit air for cooling. this will reduce drag, cool the engine better allowing for more power.

can you post multiable pics of plane so we can help you go faster?

MTK

Sounds like you never got your engine tuned right to run Avgas. Used to think the same as you (after a very brief run last year), until I tuned mine better. Avgas actually has slightly more specific energy per ounce than pump gas and must be run leaner. You will appreciate the lower exhaust note too...it appears that the slower, smoother burn results in quieter operation!!

Jezmo

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Jezmo

airrapter hit the proverbial nail on the head. You ARE going faster than what you calculate as "pitch speed". Doesn't work. My 50cc powered Extra 260 shouldn't be going 84mph according to calculated "pitch speed" but according to "radar" it is in fact going that fast. My pitch is way less than what you are using. I can't speak for your airframe drag but calculated "pitch speed" DOES NOT work on my Extra.

grossy2

Have you thought of a twin!!
Theres the MT-70 and MT-70S this has the smaller plugs.
The other option is the MLD-70, but I would change the CDI, as they use the Melody CDI, which is not much chop.
I have a 97" Gee Bee Y with a DL-100. Great Combo, no extra lead needed and is quick.
Just got my self a Gee Bee R3 50cc. Will be using a GF-55II twin in that.
Twins sound great.......

Cheers
Grossy

aussiesteve

If you want a real easy and real low cost way to get a lot more power from what you already have?

GAS /GLOW

www.rcuniverse.com/forum/m_8009384/tm.htm

Follow the steps in that exactly and you will %%%% your pants with the changes in performance

NM2K

My Feedback: (14)

Well, it appears as though we have enough answers for this week's problem.

Next week, we're going dumpster racing. You know, the same aerodynamics as the Gee Bee, but a whole lot more space in which to fit an engine! (smile)


Ed Cregger

airraptor

My Feedback: (66)

IS your "model" engine designed to run at a steady rpm state? NO
At this time i do not own any R/C gas engines, I do how ever have a highly modded yamaha raptor that i drag race in the dunes. I have seen some many times where guys will run "race gas" or "AVGAS" and "think" they now have a race engine or an engine that makes more power.

IF your engine has low compression to run just fine on 87-89 octane gas with a preset ignition timing, then why will the engine make more power on a high octane gas? It doesnt.

Your gas like you said is burning slow so how is that better? That might be good if your engine is over propped.
How much is that race gas costing you?

Anyway its a hobby and if you want to run that AVGAS then thats your choice but when you suggest it to other give them all the facts first so they can make an informed decision.

You can get some very good "race" gas in the 89-91 octane range that works very well and will give you that "race" gas smell.

skip1320

Avgas actually has slightly more specific energy per ounce than pump gas : a good one! did you mean gravity?

jaka

Hi!
Just curious?
Which GEE BEE is it? R-1,R2 Z ,D Y ?? And manufacturer?
A 55cc engine in a small 73" span 16 pund GEE BEE seems facinating!

I have Great Planes GEE BEE R-2 powered by a MVVS 15cc (.91) engine and that combo weights in at 5kg and is a hand ful to land...and yours weigh 8kg...[X(]